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Digitized by the Internet Archive 
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 The Library of Congress 
 
 http://www.archive.org/details/psychologygeneraOOjudd 
 
PSYCHOLOGY 
 
 GENERAL INTRODUCTION 
 
 BY 
 
 CHARLES HUBBARD TUDD 
 
 I 
 
 PROFESSOR OF EDUCATION AND DIRECTOR OF THE 
 SCHOOL OF EDUCATION OF THE UNIVERSITY OF CHICAGO 
 
 SECOND COMPLETELY REVLSED EDITLON 
 
 f wi P 
 
 GINN AND COMPANY 
 
 BOSTON • NEW YORK • CHICAGO • LONDON 
 ATLANTA • DALLAS • COLUMBUS • SAN FRANCISCO 
 
COPYRIGHT, 1907, BY CHARLES SCRIBNER'S SONS 
 
 COPYRIGHT, 1917, BY CHARLES HUBBARD JUDD 
 
 ALL RIGHTS RESERVED 
 
 317-9 
 
 -^^'^ 
 
 -b^ 
 
 ^!.-A 
 
 x"^^ 
 
 I 
 
 / 
 
 OCT -5 1917 
 
 GINN AND COMPANY • PRO- 
 PRIETORS • BOSTON • U.S.A. 
 
 CI.A473861 
 
PREFACE TO THE SECOND EDITION 
 
 This revised edition has been very largely rewritten. The 
 emphasis which was laid on motor processes' in the volume 
 when it appeared in 1907 has been more than justified by 
 recent developments of ''behaviorism" in psychology. The 
 present edition goes further than did the first in working out 
 the doctrines of functional psychology, especially in so far as 
 these use motor processes in explaining mental organization. 
 
 The doctrine of attitudes which was presented in the 
 first edition has been much expanded. 
 
 The applications of psychology have been elaborated, 
 especially through a new chapter on mental hygiene. 
 
 The view with regard to the importance of consciousness 
 in evolution which was set forth in my paper before the Amer- 
 ican Psychological Association in 1909 has been adopted as 
 a guiding principle in this volume. In keeping with this 
 view, the chapter on volition has been wholly rewritten, and 
 several earlier sections have been largely worked over. 
 
 Perhaps the simplest method of economizing the time 
 of those who are interested merely in the new parts will 
 be to enumerate the chapters which are not greatly modi- 
 fied. These are Chapters I, II, III, V, VIII, IX, X, XI, 
 XIV, and XVII. The remai,^)der of the volume includes 
 liberal revisions. Chapters IV, VI, VII, XII, XV, and 
 XVI are new or very largely so. The book has been freed 
 so far as possible from technical controversial discussions, 
 with the result that some chapters, notably Chapter XIII, 
 have been reduced. 
 
 Ill 
 
iv PSYCHOLOGY 
 
 Many new obligations have accumulated since the first 
 
 edition appeared. Those who have used the book in 
 
 class or have read it in individual study have in many 
 
 instances sent to the author helpful criticisms. All of 
 
 these have been kept in mind in the revision and are 
 
 here gratefully acknowledged. 
 
 C H. J. 
 Chicago, Illinois 
 
PREFACE TO THE FIRST EDITION 
 
 There is very general agreement as to the main topics 
 which must be treated in a textbook on psychology. There 
 is, however, no accepted method of approaching these 
 topics, and, as a result, questions of emphasis and propor- 
 tion are always matters of individual judgment. It is, 
 accordingly, not out of place for one to attempt in his 
 preface to anticipate the criticism of those who take up 
 the book, by offering a general statement of the princi- 
 ples which have guided him in his particular form of 
 treatment. This book aims to develop a functional view 
 of mental life. Indeed, I am quite unable to accept the 
 contentions or sympathize with the views of the defenders 
 of a structural or purely^- analytical psychology. In the 
 second place, I have aimed to adopt the genetic method 
 of treatment. It may be well to remark that the term 
 ''genetic" is used here in its broad sense to cover all that 
 relates to general evolution or individual development. In 
 the third place, I have attempted to give to the psycho- 
 logical conditions of mental life a more conspicuous place 
 than has been given by recent writers of general textbooks 
 on psychology. In doing this I have aimed to so coordi- 
 nate the material as to escape the criticism of producing 
 a loose mixture of physiology and introspective description. 
 In the fourth place, I have aimed to make as clear as 
 possible the significance of ideation as a unique and final 
 stage of evolution. The continuity running through the 
 evolution of the sensory and motor functions in all grades 
 of animal life is not, I believe, the most significant fact for 
 psychology. The clear recognition of this continuity which 
 
vi PSYCHOLOGY 
 
 the student reaches through studies of sensation and habit, 
 and even perception, is the firmest possible foundation on 
 which to base an inteUigent estimate of the significance 
 of human ideational processes. The clear comprehension 
 of the dominant importance of ideational processes in man's 
 life is at once the chief outcome of our study and the com- 
 plete justification for a science of psychology, distinct from 
 all of the other special disciplines which deal with life and 
 its variations. The purpose of this book may therefore be 
 stated in terms which mark as sharp a contrast as possible 
 with much that has been said and written of late regarding 
 the advantages of a biological point of view in the study 
 of consciousness. This work is intended to develop a 
 point of view which shall include all that is given in the 
 biological doctrine of adaptation, while at the same time it 
 passes beyond the biological doctrine to a more elaborate 
 principle of indirect ideational adaptation. 
 
 In the preparation of this book I am under double obli- 
 gation to A. C. Armstrong. As my first teacher in psy- 
 chology, he has by his broad sympathies and critical insight 
 influenced all of my work. Furthermore, he has given me 
 the benefit of his judgment in regard to all parts of this 
 book while it was in preparation. Two others I may men- 
 tion as teachers to whom I am largely indebted. The 
 direct influence of Wilhelm Wundt will be seen at many 
 points in this book. As the leader in the great advances 
 in modern psychology, especially in the adoption of experi- 
 mental methods, and as the most systematic writer in this 
 field, he has left his impression on all who have worked 
 in the Leipzig laboratory to an extent which makes such 
 a book as this in a very large sen^e of the word an expres- 
 sion of his teaching. Finally, I am indebted to William 
 James. I have received instruction from him only through 
 his writings, but take this opportunity of acknowledging his 
 unquestioned primacy in American psychological thought 
 
PREFACE vii 
 
 and the influence of his genius in turning the attention of 
 all students to the functional explanations of mental life 
 which it is one of the aims of this book to diffuse. 
 
 My colleagues, Dr. R. P. Angier and Dr. E. H. Cameron, 
 read the manuscript and gave me many valuable sugges- 
 tions which have been incorporated into the text. Mr. C. H. 
 Smith assisted me in the preparation of the figures. 
 
 C. H. J. 
 New Haven, Connecticut 
 
CONTENTS 
 
 PAGE 
 
 CHAPTER I. THE SCOPE AND METHODS OF 
 
 PSYCHOLOGY i 
 
 Psychology a study of conscious processes. The motive of wonder. 
 Discovery of individual differences as motive. Differences between 
 experience and physical facts. Place of consciousness in evolution. 
 The first method of psychology. Nervous processes as conditions of 
 consciousness. Studies of behavior. Overemphasis of slower forms 
 of mental activity through introspection. Experiment in psychology. 
 Explanation at variance with mere observation. Subdivisions of 
 psychology. Summary and definition of psychology. Definitions of 
 certain general psychological terms. 
 
 CHAPTER H. THE BODILY CONDITIONS OF BE- 
 HAVIOR AND EXPERIENCE 14 
 
 The introspective approach. Indirect method of approach to psy- 
 chological facts. Characteristics of unicellular animals. Simplest 
 types of behavior. Consciousness no more complex than behavior. 
 Behavior more limited than sensitivity. Specialization of cell struc- 
 tures and functions in higher animals. Specialized nervous processes. 
 Nervous processes of three distinct types. Behavior varied and much 
 more complex. Progressive evolution in both structure and behavior. 
 Centralized nervous system. Coordinating center of the body. Com- 
 plex paths within the nervous system. Experience comparable to 
 the lower forms of human experience. Differentiation of vertebrate 
 central nervous system. Two types of higher centers : first, higher 
 sensory centers ; second, indirect centers. Large indirect centers 
 characteristic of highest animals. Traces of past impressions also 
 present. Meaning of evolution of complex organisms. Inner organi- 
 zation essential to highest forms of personal behavior. Characteristics 
 of behavior of higher animals. 
 
 CHAPTER III. THE HUMAN NERVOUS SYSTEM . . 38 
 
 External plan like that of all vertebrates. General plan of the minute 
 nervous structure as related to consciousness. The nerve cell and its 
 parts. Complexity of structure related to forms of action. Synapses 
 as paths of organization. Paths in spinal cord. Reflex tracts. Trans- 
 mission to higher centers. All nervous organs in part independent 
 
 ix 
 
X PSYCHOLOGY 
 
 ♦ PAGE 
 
 centers. Cerebellum. Cerebrum and its systems of fibers. Structure 
 of cerebrum as indicating way in which impulses are organized. Cere- 
 bral cortex complex. Localization of functions. Stimulation the first 
 method of discovering cerebral localization. Extirpation and com- 
 parison of pathological cases. Embryological methods. Association 
 areas. Significance of the central position of the general motor area. 
 Speech centers. Broca's convolution an association center. Phre- 
 nology not in accord with clearly known facts. Frontal association 
 area. General principles of nervous action. Active organs as termini 
 of all nervous impulses. Principle of facilitation. Principle of asso- 
 ciation of centers of high tension. Diffusion as opposed to organiza- 
 tion. Principle of progressive organization. 
 
 CHAPTER IV. CLASSIFICATION OF CONSCIOU^S 
 
 PROCESSES 6i 
 
 Classification derived from study of nervous organs. Classification 
 from observation superficial. Historical threefold classification. His- 
 torical twofold classification. Classification according to nervous 
 processes. Example of scientific analysis and classification. Relation 
 of classification to introspection. Sensations. Reactions and atti- 
 tudes. Fusion and perception. Memory. The process of ideation. 
 Higher forms of action. Relation to historic classification. Practical 
 applications. 
 
 CHAPTER V. SENSATIONS '...... 71 
 
 Sensations not copies of external forces. Laws of sensation as one 
 of the first problems in psychology. Relation of sensations to sen- 
 sory nervous processes. Sensations as elements. Psycho-physics as 
 a division of psychology. Meaning of term ^'quality." Chromatic 
 (or color) series and achromatic (or gray) series. Fundamental color 
 names. The color spectrum and circle. Saturation, brightness, and 
 mixtures. External light. Comparison of physical and mental series. 
 Relation between the physical and the psychical facts dependent in 
 part on the organs of sense. Evolution of organ of vision. Organ of 
 sense as selective organ. The human eye — its muscles. The outer 
 wall and the lens. Transparent media. Choroid coat. The retina. 
 Rods and cones and their functions. Color blindness. Color-mixing. 
 Pigment-mixing subject to physical law. After-images. Contrasts. 
 Theories of color vision. Mrs. Franklin's ge.netic theory of processes 
 in the retina. Physical sound. Pitch, or tonal quality. Intensity, or 
 loudness. Complexity of a regular type the source of differences in 
 timbre. Noise due to irregular vibrations. Evolution of the ear. The 
 human ear, pinna, and meatus. The tympanic membrane. Air cham- 
 ber on inner side of the tympanic membrane. Chain of ossicles. The 
 inner ear. The semicircular canals. The cochlea and sensory areas 
 
CONTENTS ' xi 
 
 PAGE 
 
 in the vestibule. Sensory cells in the cochlea. Contrast between 
 auditory and visual processes. Beats, difference tones. Summation 
 tones. Harmony not a matter of sensation. Absence of after-images 
 in auditory sensations. Tone deafness. Taste and smell differenti- 
 ations of a primitive chemical sense. Position of olfactory organ in 
 the nasal cavity. Structure and function of the olfactory surface. 
 Olfactory stimuli. Smell a rudimentary sense in man. Taste quali- 
 ties and taste organs specialized. Organs of taste. Gustatory stimuli. 
 Organs of touch. Differentiation of the tactual fibers ; temperature 
 spots. Pressure spots. Other '' spots." Relativity of temperature 
 sense ; chemical and mechanical senses. Organs of touch at the 
 periphery. Muscle sensations and organic sensations. Intensity a 
 general characteristic. Weber's Law. General statement of the law. 
 Mechanical explanation of Weber's Law. Other views regarding 
 Weber's Law. 
 
 CHAPTER VL EXPERIENCE AND BEHAVIOR ... 130 
 
 All consciousness complex and selective. The selective character 
 of conscious processes related to sensory impressions. Selective 
 consciousness related to behavior. Common interests and their re- 
 lation to behavior. Study of evolution of organs of action as impor- 
 tant as study of senses. Evolution from gross muscles to highly 
 differentiated muscles. Behavior dependent on nervous control. 
 Coordination as necessary counterpart of differentiation. Individual 
 development in behavior. Inherited coordinations or instincts. 
 Glands as active organs. A constant tension of active organs 
 as background of all behavior. Meaning of sensory impressions 
 dependent upon inner conditions. Sensory processes and the 
 equilibrium of action. Importance of sensations dependent on 
 organization. Sensations unduly emphasized through introspection. 
 Attitudes. Attitudes not related to sensations but to behavior. 
 Relation of sensation to reaction. 
 
 CHAPTER VII. CERTAIN FUNDAMENTAL ATTI- 
 TUDES 146 
 
 Reactions toward objects and reactions away from objects. Pleasure 
 and displeasure. Cultivated feelings. Fear as a typical emotion. 
 How to change the attitude of fear. Fear an emotion of complex 
 beings. Fear and pathology. Parental love and altruism. Anger. 
 Other emotions. Emotions as fundamental forms of experience. 
 1' Higher forms of experience as related to behavior. Feelings of 
 organic type. Flexor and extensor movements related to character- 
 istic attitudes. Changes in circulatory movements as parallels of 
 conscious changes. Disappointment as negative emotion. External 
 attitudes. Attention as an attitude. Experiment to demonstrate 
 
xii * PSYCHOLOGY 
 
 PAGE 
 
 tension. Various forms of attention. Sympathy with fellow beings. 
 Sympathy involved in all recognition of objects. Illusion due to 
 muscular tension. Such muscular tensions common to many experi- 
 ences. All consciousness a form of sympathetic attention. Attitudes 
 as related to higher processes of recognition. . 
 
 CHAPTER VIII. COMBINATION AND ARRANGE- 
 MENT OF SENSATIONS 162 
 
 Sensory experience always complex. Sensation combinations or 
 fusions. Space not a sensation, but a product of fusion. Tactual 
 space as a simple example of fusion. Subjective and objective 
 space. Perception and training. Development of spatial arrange- 
 ments in the course of individual experience. Vision and move- 
 ment as aids to touch. Tactual percepts of the blind. Wundt on the • 
 tactual perception of the blind. Lotze's local signs. Inner tactual 
 factors. Space not attached to any single sense. General conclu- 
 sions regarding tactual space. Auditory recognition of location. 
 Influence of movements in auditory experience of position. Quali- 
 tative differences and localization. Distance of sounds recognized 
 only indirectly. Unfamiliar sounds difficult to locate. Visual space 
 and optical illusions. Effects of practice. Percepts always complex. 
 Contrast. Common facts showing size to be a matter of relations. 
 Physiological conditions of visual perception. Psychological state- 
 ment. Photographic records of percepted movements. Relation 
 between size and distance. Definite optical relation between the 
 distance and the size of an object and the size of the retinal image 
 from this object. Berkeley's statement of the problem of visual 
 depth perception. Experiments on binocular vision. Difference 
 between the images in the two eyes. Stereoscopic figures and 
 appearance of solidity. Retinal rivalry. Factors other than those 
 contributed by the two eyes. Aerial perspective. Geometrical per- 
 spective and familiarity. Shadows. Intervening objects. Depth a 
 matter of complex perception. Relation to movements. General 
 movements as conditions of fusion of retinal sensations.. Space 
 a system of relations developed through fusion. Movement and 
 mechanical laws. Perception of individual objects. Mere coexist- 
 ence of sensations no explanation of unity in the percepts of 
 objects. Range of fusion determined by practical considerations. 
 Changes in percepts through repetition. Parallel development of 
 perception and habit. Time as a general form of experience. Ex- 
 perimental determination of the scope of "the present." Scope of 
 " the present " and its varying conditions. Time relations in verse 
 and related systems of experience. Time arrangement as condi- 
 tioned by the rhythmical changes in nervous processes. Perception 
 more than the flux of sensations. Discussions of perception. 
 
CONTENTS xiii 
 
 PAGE 
 
 CHAPTER IX. HABITS 195 
 
 Organic retentiveness. Remoter conditions of retention. Instincts. 
 Protective instincts. Food-taking instinct. Instincts established 
 through selection. Delayed instincts common. Impossibility of dis- 
 tinguishing instincts from later-acquired forms of behavior. Habits 
 from instincts and from independent conditions. Development of 
 habit through conflict of instincts. Nervous development concerned 
 in the selection of instincts. Habit as a modified instinct. Importance 
 of heredity in explaining consciousness. Diffusion a mark of lack 
 of organization. Development of habit from diffusion. Undeveloped 
 movements. Diffusion analogous to all forms of overproduction. 
 Conscious correlates of habit. Instinct, habit, and mental attitudes. 
 Applications of the doctrine of attitudes to social science. 
 
 CHAPTER X. SPEECH AS A FORIVl OF BEHAVIOR . 209 
 
 Speech as a highly important special habit. Speech and ideas closely 
 interrelated. Speculations regarding the nature and origin of speech. 
 The special creation theory. The imitation theory. The interjection 
 theory. Roots of language in natural emotional expressions and their 
 imitation. Imitation. Other imitative communications of animals and 
 man. Value of sounds as means of social communication. Limita- 
 tion of forms of animal communication. The first stages of human 
 articulation like animal cries. Articulations selected from the sum 
 of possible activities. Evolution of ideas and speech. Gestures and 
 broad scope of attention. Evolution of gestures in direction of sim- 
 plification. Speech a highly specialized mode of behavior. Conse- 
 quences of specialization. Speech an indirect form of behavior. 
 Evolution of writing. Writing at first direct in form. Images 
 reduced to lowest terms as powers of reader increase. Written 
 symbols and their relation to sounds. The alphabet. Social motives 
 essential to the development of language. Social system as source 
 of the form of words. Social usage and the domination of individual 
 thought. Social ideas dominate individual life. Experimental evi- 
 dence of importance of words. Number terminology as a device 
 for recording possessions. Symbols for groups of tallies. Parallel 
 growth of number names and system of ideas. Development of 
 arithmetic depends on an appropriate system of numerals. Social 
 world unified through common forms of thought. Changes in words 
 as indications of changes in individual thought and social relations. 
 Illustration of change in words. Words as instruments of thought 
 beyond immediate experience. Images and verbal ideas. Mental 
 attitudes as characteristic phases of verbal ideas. Other illustrations 
 of thought relations. Concrete words. Examples of words arousing 
 tendencies toward action. Abstract words. Contrast between con- 
 crete images and abstract ideas. Particular images as obstructions to 
 thought. Ideas or indirect forms of experience characteristic of man. 
 
xiv PSYCHOLOGY 
 
 PAGE 
 
 CHAPTER XI. MEMORY AND IDEAS ... . . . 240 
 
 The problem of describing ideas. Ideas not derived from present 
 impressions. Ideas as revivals. Advantages of relative independ- 
 ence of sensory impressions. Individual variations in imagery. The 
 accidents of individual experience and mental imagery. Dependence 
 on vividness and recency. The training of memory. Retention as 
 distinguished from recall. Association by contiguity. Association 
 by similarity. Association by contrast. New products evolved in 
 ideation. Ideas not all images. Tendency to revert to imagery type. 
 Advantages of indirect forms of experience. Animal behavior direct 
 and perceptual, human behavior indirect and ideational. Influence 
 of ideas on things. Tool-consciousness. Knowledge of nervous 
 process limited. Consciousness as product of evolution. 
 
 CHAPTER XII. IMAGINATION AND THE FORMA- 
 TION OF CONCEPTS 251 
 
 Adaptation through ideas. Early stages of barter. Barter perceptual. 
 Standard values. Symbolic values. Evolution from perception to 
 ideas. Higher controls of conduct. Ideational attitudes. Ideas as 
 substitutes for impressions. Imagination as reorganization of ideas. 
 Personifying imagination. Imaginations occasions of useless activi- 
 ties. Critical tests of imaginations. Empirical test often inapplica- 
 ble. The test of internal agreement. The criterion of coherency a 
 product of development. The demand for coherency as exhibited 
 in constructive scientific ideas. Uncritical imaginations. Literary 
 imagination and the canon of coherency. The uncritical forms of 
 thought which preceded science. First sciences limited to facts 
 remote from life. Scientific concepts. Validity of concepts. Abstrac- 
 tion. Generalization. Judgments and reasoning. Logic. Primitive 
 belief. Belief after hesitation. Belief a positive psychological fact. 
 Spurious verbal beHef. Habitual belief. Religious belief not in- 
 stinctive. Sentiments not instinctive. Social life and the higher 
 mental processes. Fields for the application of psychology of ideas. 
 
 CHAPTER XIII. THE IDEA OF THE SELF .... 269 
 
 The idea of self sometimes regarded as matter of direct knowledge. 
 Idea of self a concept. First stages of personal development not 
 self-conscious. Gradual discrimination of self from things. Child's 
 early notion of self largely objective. The idea of self as related to 
 discrimination between the objective and subjective. The self dis- 
 covered by contrast with not-self. Social consciousness and self- 
 consciousness. The self at first not a scientific concept, but a 
 practical concept. Cultivated self-consciousness. The religious 
 motive for self-consciousness. Scientific idea of personality. The 
 chief item in the concept of life the abstract idea of organization. 
 
CONTENTS XV 
 
 PAGE 
 
 Unity of self. The self as an efficient cause. Self as a valid scien- 
 tific concept. Concept of unity. The self a concept. 
 
 CHAPTER XIV. DISSOCIATION 278 
 
 Disorganized personality in contrast with normal self. Illusions and 
 hallucinations. Sleep, the influence of drugs, hypnosis, and insanity 
 as forms of disorganization. The physiological conditions of sleep. 
 The closing of avenues of stimulation in sleep. Various degrees of 
 dissociation. Dissociation in the central processes. Dreams as dis- 
 sociated groups of ideas. Dreams impressive only because they are 
 uncriticized. Motor processes suspended by dissociations in sleep. 
 Narcotic drugs dissociative in their effects. Effect of alcohol on 
 the nervous system. Overexcitation is also dissociative. Toxic 
 effects of certain diseases. These negative cases as evidences of the 
 relation between normal consciousness and organization. Hypnosis 
 a form of dissociation closely allied to sleep. Hypnosis as partial 
 dissociation. Methods of inducing hypnosis. Hypnosis more readily 
 induced after it has once been established in a subject. Various 
 characteristics of the hypnotized subject. Ideas not subjected to 
 criticism in hypnosis. Dual personalities in hypnosis. Dual per- 
 sonalities in other than hypnotic conditions. Dual and multiple per- 
 sonalities analogous to the various selves of normal life. Hypnosis 
 a transient condition, insanity permanent. Movements sometimes 
 normal in hypnosis, because the lower centers are not dissociated. 
 The after-effects of hypnosis tend to become permanent. Insanity 
 a permanent form of disorganization, introduced in many cases by 
 dissociation and settling into an abnormal reorganization. Melan- 
 cholia as a typical form of dissociation. Excessive excitation as a 
 second typical case of insanity. Fundamental disturbances of in- 
 stinctive and emotional life. Relation of psychiatry to psychology. 
 
 CHAPTER XV. VOLUNTARY ACTION AND VOLUN- 
 TARY ATTENTION 301 
 
 Voluntary action a special form of behavior. Instinctive behavior 
 different from voluntary action. Impulsive acts distinct from higher 
 forms of voluntary action. Impulsive acts as phases of general mus- 
 cular tension. Impulsive acts explicable through nervous organiza- 
 tion. Impulse comparable to involuntary attention. Impulse and 
 involuntary attention related to perception and habit. Simple case 
 of choice. Behavior of the higher types dependent on ideas. Volun- 
 tary action and its complex background as contrasted with lower 
 forms of behavior. Decision a process of balancing ideas. Decision 
 largely influenced by organization built out of past experiences. 
 The meaning of prevision. The problem of the freedom of the will. 
 Voluntary choice guided by purposes. Behavior of a higher type 
 
xvi PSYCHOLOGY 
 
 PAGE 
 
 is related to education. Early scientific studies of behavior purely 
 external. Purely external investigations not productive. Recent 
 investigations and their stress on introspection and analysis of 
 movement. Analysis of the form of movement. Concept of organ- 
 ization as fundamental in all psychological studies. 
 
 CHAPTER XVI. MENTAL HYGIENE . ... . . . 314 
 
 Hygiene a suggestive term for psychology. Relation of psycho- 
 logical hygiene to physiological. Coordination of bodily activities. 
 Control of excessive stimulations. Perceptual analysis. Perceptual 
 synthesis. Dangers of specialization. Control of perceptual atti- 
 tudes. Control of attitudes as a case of volition. Rules of whole- 
 some ideation. Economy of mental effort. Preparation as aid to 
 memory. Organization the key to all correct thought. The domi- 
 nation of thought by some leading idea. Language of great im- 
 portance in furnishing central ideas. The ineffectiveness of a 
 detached verbal idea. Higher organization as a cure for verbalism. 
 Self-directed organization as the goal of the higher mental life. 
 
 CHAPTER XVII. APPLICATIONS OF PSYCHOLOGY . 325 
 
 Psychology a basis of scientific thinking about human conduct. 
 Design in art as a psychological fact. Freedom in art. Architectural 
 harmony analogous to musical rhythm and harmony. Literary art 
 and ps^'-chological laws. Prose rhythms as related to the personal 
 organization of writers. Verse another example of the same type. 
 Literary content controlled by psychological laws. Feeling and 
 intuition. Many of the social sciences predominantly objective in 
 their methods. Introspective psychology and its limited support 
 to social science. Interrelation of psychology and social science. 
 Human evolution psychical. An hypothesis to explain the break be- 
 tween man and the animals. Spencer's application of psychology to 
 sociology. Relation of educational practices to scientific psychology. 
 Psychology as a preparation for the intelligent diagnosis of particular 
 situations which arise in educational practice. A curve illustrating 
 the process of learning. Significance of a '' plateau " in development. 
 Other examples of the same type of development. Motor habits in- 
 termittent. School training in its relation to the stage of develop- 
 ment attained by the mind. Significance of scientific studies often 
 indirect. Expression as an essential condition of mental life. Psy- 
 chology historically a part of philosophy. Relation of psychology to 
 philosophy closer than that of any of the special sciences. Psy- 
 chology and logic. Psychology and aesthetics. Psychology and 
 ethics. Psychology and metaphysics. 
 
 INDEX 
 
 349 
 
LIST OF ILLUSTRATIONS 
 
 FIGURE PAGE 
 
 1 . Diagram for use in demonstration of the blind spot .... 9 
 
 2. Movements of a unicellular animal 16 
 
 3. The hydra 18 
 
 4. Much-enlarged section of a muscle cell and a sensory cell of a 
 
 hydra, together with the connecting cells which lie between 
 them 20 
 
 5. Outline of a starfish, and nervous system of the same ... 24 
 
 6. A stag beetle, showing the outline of the body and the dis- 
 
 tribution of the nerve cells and fibers 25 
 
 7. The nervous system of a frog as it would appear if the skin 
 
 and muscles and protecting bone were removed . . . . 28 
 
 8. Plate showing successive stages in the evolution of the verte- 
 
 brate nervous system 31 
 
 9. General form and position of central nervous organs ... 38 
 
 10. Two nerve cells 39 
 
 1 1 . A number of different types of connection between nerve fibers 
 
 and cells 40 
 
 1 2. The development in complexity of nerve cells in the course of 
 
 animal evolution and in the course of the development of a 
 single individual 41 
 
 13. Transverse section across the spinal cord 42 
 
 14. A diagram to illustrate the course of the sensory stimulation 
 
 when it passes upward from the level of the spinal cord at 
 which it is received 44 
 
 15. A diagrammatic section through a part of one of the folds in 
 
 the cerebellum 45 
 
 16. The brain seen from below and cut open to show the paths of 
 
 fibers from the cortex of the cerebrum to the lower organs 46 
 
 17. Sketch showing some of the association fibers connecting vari- 
 
 ous parts of the cortex of the cerebrum with one another 47 
 
 18. A transverse section across the two hemispheres in a plane 
 
 passing vertically through the cheek bones parallel to a 
 
 line connecting the two ears 48 
 
 xvii 
 
xviii PSYCHOLOGY 
 
 FIGURE PAGE 
 
 19. Two sections representing portions of the cerebral cortex from 
 
 two areas of the human brain . 49 
 
 20. A diagrammatic section showing the structure of the cortex 
 
 of the cerebrum 50 
 
 21. The outUne of the lateral surface of the cerebrum with the 
 
 typical convolutions, as given by Flechsig . . . . . 52 
 
 22. The median surface of the human cerebrum showing, as in 
 
 Fig. 21, the various areas 53 
 
 23. Color circle 76 
 
 24. Wave forms ^^ 
 
 25. A series of eyes which have reached various levels of 
 
 development 82 
 
 26. Diagrammatic section of the human eye 85 
 
 27. A diagrammatic section of the retina 88 
 
 28. Diagrammatic section showing the structure of the ear . . 104 
 
 29. Diagrammatic section of the sensory cells in the vestibule . 108 
 
 30. The structure in the cochlea as seen when a transverse sec- • 
 
 tion is made across the canal 109 
 
 3 1 . Diagram to represent the formation of beats 113 
 
 32. The inner cavity of the nose 116 
 
 33. Section showing the different cells which compose the mucous 
 
 lining of the nose in the olfactory region 117 
 
 34. Olfactory cells and supporting cells . 118 
 
 35. The depression between the sides of two papillae on the sur- 
 
 face of the tongue . . 119 
 
 36. A diagrammatic section of a single taste bulb showing the 
 
 character of the different cells 1 20 
 
 37. A diagramimatic sketch showing two neighboring taste bulbs 121 
 
 38 A. Tactual end organs . 124 
 
 38 B. A Pacinian corpuscle 124 
 
 38 C. A Missenian corpuscle 124 
 
 39. Two Golgi-Mazzoni corpuscles of the type found by Ruffini 
 
 in the cutaneous connective tissue of the tip of the 
 human finger ' 125 
 
 40. The complex distribution of a tactual nerve fiber in the 
 
 immediate vicinity of a hair 126 
 
 41. Tooth of Gobinus showing distribution of nerve fiber through- 
 
 out the canal of the tooth . . . 127 
 
LIST OF ILLUSTRATIONS xix 
 
 FIGURE PAGE 
 
 42. A highly developed muscle cell 134 
 
 43. The contracted and relaxed state of a muscle 135 
 
 44. Diagram showing relation of sensory impressions to reactions 1 43 
 
 45. Involuntary hand movements made by the right and left hands 
 
 of an observer who is thinking of a building situated in 
 
 front of him 157 
 
 46. Unaesthetical balance 158 
 
 47. Miiller-Lyer illusion 172 
 
 48. Illusion of contrast 1 74 
 
 49. Zollner illusion 176 
 
 50. Poggendorff illusion 1 76 
 
 5 1 . Figures showing the path followed by the eye of an observer 
 
 in examining certain of the foregoing illusions . . . . 177 
 
 52. Relation of retinal image to objects 179 
 
 53. Binocular parallax 182 
 
 54. An Ojibwa love letter 220 
 
 ^^. Ancient and modern Chinese writing 221 
 
 56. Derivation of the Roman letter M from the ancient Egyptian 
 
 hieroglyphic owl 222 
 
 ^y. Association by similarity ^ 245 
 
 58. Fatigued cells - 280 
 
 59. Curve showing the intensity of sound necessary to awaken a 
 
 sleeper at different periods of sleep 282 
 
 60. Curves for sending and receiving telegraphic messages . . 338 
 
 61. Analysis of the receiving curve 340 
 
PSYCHOLOGY 
 
 CHAPTER I 
 
 THE SCOPE AND METHODS OF PSYCHOLOGY 
 
 Psychology a study of conscious processes. '' The under- 
 standing, like the eye, whilst it makes us see and perceive 
 all other things, takes no notice of itself ; and it requires 
 art and pains to set it at a distance, and make it its own 
 object." 1 Thus did one of the earliest Enghsh psychologists 
 point out the distinction between ordinary experience and 
 the scientific study of mental processes. A man may be 
 afraid, or enthusiastic, or lost in reverie ; in each case his 
 mind will be full of emotions and ideas, but he will not be 
 led by the intensity of his experiences to make them sub- 
 jects of analysis and explanation. Indeed, the more he is 
 absorbed in the experience itself, the less likely he is to 
 psychologize about himself. We all have the raw materials 
 for a science of mental processes within us, but we require 
 special motives to lead us to that careful study of these 
 processes which gives rise to the science of psychology. 
 
 The motive of wonder. The motives which have led men 
 to make a scientific study of their conscious processes are 
 numerous and varied in character. Perhaps the most com- 
 mon of these motives is to be found in the exceptional and 
 baffling experiences through which one passes from time to 
 time. I think I hear a voice, but find on examination that 
 no one spoke. I try to grasp an object, but find that for 
 
 1 John Locke, Essay concerning Human Understanding, Bk. I, chap, i, 
 sect. I. 
 
2 PSYCHOLOGY 
 
 my sense of touch the thing is not what it seems to be for 
 my sense of vision. Such experiences as these require some I 
 explanation, and even the most superficial observer is likely 
 to become interested, at least for the moment, in their inter- 
 pretation. Popular psychology seldom gets beyond this ex- 
 amination of striking and unique experiences ; consequently 
 the notion has gained wide currency that psychology is 
 devoted entirely to the investigation of occult phenomena. 
 
 Discovery of individual differences as motive. Interest in 
 exceptional experiences is hardly a sufficient motive, how- 
 ever, to lead to long-continued systematic study. It is to be 
 doubted whether psychology would ever have developed into 
 a serious science unless other more fundamental motives 
 had arisen to turn the attention of men to the examination 
 and explanation of their conscious processes. The more 
 fundamental motives began to appear as far back as the time 
 of the Greeks. These early thinkers found themselves in 
 bitter intellectual controversies. Given the same facts and 
 the same earnest effort to use these facts in the establish- 
 ment of truth, the Greeks found that two individuals often 
 arrive at opposite conclusions. This made it clear that like 
 facts may lead in two different minds to entirely different 
 processes of thought. So striking were the individual dif- 
 ferences that early thinkers despaired of finding any general 
 laws. Gradually, however, as the way in which men remem- 
 ber and the way in which men relate their ideas were studied, 
 it became apparent that back of the seeming variety there 
 are certain common forms of consciousness, certain funda- 
 mental laws of mental activity which can be discovered and 
 systematically arranged into a science of mental life. To this 
 task the Greek philosophers set theinselves wdth enthusiasm, 
 though with inadequate methods, and out of their efforts arose 
 the earliest schools of serious psychological investigation. 
 
 Differences between experience and physical facts. An- 
 other fundamental motive appeared early in the modern 
 
SCOPE AND METHODS OF PSYCHOLOGY 3 
 
 period as a direct outgrowth of the discovery that there is 
 a disparity between the facts discovered by physical science 
 and the direct testimony of consciousness. Thus Sir Isaac 
 Newton discovered that he could break up white hght into 
 all the colors of the rainbow. Conscious experience of 
 white light is, on the contrary, absolutely simple and unana- 
 lyzable. Even among the students of physical science there 
 had never been any hesitation up to the time of Newton 
 in assuming that external white light is just as simple as 
 human consciousness of whiteness. The ancients had a 
 definite explanation of vision which shows that they explic- 
 itly believed in the simplicity of external white light. Light ' 
 was for them a series of particles emanating from the object 
 and entering the eye. When they saw white, they believed 
 that the experience was due to white particles in the eye, 
 and that these white particles came from a white body. All 
 was uninterrupted likeness from the physical object to con- 
 sciousness. Such an explanation of white light as that 
 offered by the ancients was rendered utterly untenable by 
 Newton's discovery. When further investigations led physi- 
 cists to define light and other forms of physical energy 
 as modes of vibration, the breach between conscious experi- 
 ence and external reality became so wide that men felt com- 
 pelled to study conscious experience as well as physical facts. 
 It is noteworthy that the period during which Newton and 
 his successors were making their discoveries in physics was 
 a period of the profoundest interest in psychological problems. 
 Place of consciousness in evolution. As reenforcements 
 to the impetus given to psychological study by discoveries 
 in physics, new motives for such study arose with the 
 development of physiology, and especially with the estab- 
 lishment of the biological doctrine of evolution. Every 
 highly developed function of an animal is recognized in 
 biology as having its relation to the struggle for existence. 
 If an animal can run well, we find this ability serviceable 
 
4 PSYCHOLOGY 
 
 in saving the animal from enemies, or in helping it to 
 procure food. If an animal has keen vision, we find that 
 the animal depends on this sense in the essential activities 
 of life. With such facts clearly before us, we cannot escape 
 the question, What part does consciousness play in the 
 economy of life ? From the lower forms of animal life up 
 to the highest, we find a steady increase in the scope of 
 intelligence. In the highest animals we find mental evolu- 
 tion carried so far that' intelligence is very often of more 
 significance than any other single function or even group 
 of functions. Certainly this is true of man. The digestive 
 functions of a man differ very little from those of the 
 higher animals ; the muscles and bones and organs of cir- 
 culation in man are very much like those of his near rela- 
 tives in the animal kingdom. In matters of intelligence, on 
 the other hand, man has never been in any doubt as to the 
 wide difference between himself and even the highest of 
 the animals. Man lives in a world of ideas from, which 
 animals are excluded by their lack of intelligence and by 
 their lack of that means of social intercourse which is the 
 possession of man alone, namely, language. Furthermore, 
 in his dealings with the physical world man discovered the 
 use of tools through which he has been able to reshape his 
 environment. Man has, in short, through his conscious 
 activities, attained to a mode of struggle for existence which 
 is unique. We cannot understand and explain human life 
 and human institutions without studying the facts and laws 
 of consciousness, without raising the question of the relation 
 of consciousness to all of man's other attributes. 
 
 The first method of psychology. The methods of psy- 
 chological investigation have progressed with the rise of 
 each new motive for the study of conscious life. At first, 
 the method was one of direct self -observation. This method 
 J is known as introspection. When one has an emotion, others 
 may see its external expressions, but only the man himself 
 
SCOPE AND METHODS OF PSYCHOLOGY 5 
 
 can observe the conscious state which constitutes the emo- 
 tion.^ In looking inward and observing this conscious state, 
 one is said to introspect. 
 
 The early psychologists were so impressed with the 
 importance of introspection that they regarded it as the 
 sole method of collecting facts for their science. They thus 
 seriously limited the scope of their studies. Mental proc- 
 esses are fully understood only when the relations of these 
 inner events to the outer world are taken into account. 
 When a man meets his friend and greets him, the psychol- 
 ogist is interested not only in the inner fact of conscious 
 recognition but also in the impression made on the eye, for 
 it is in this impression that recognition originates ; further- 
 more, the psychologist must study the bodily activities of 
 greeting which follow recognition. Indeed, the most pro- 
 ductive discoveries of modern psychology have come from 
 a study of the setting in which conscious processes belong. 
 
 Nervous processes as conditions of consciousness. Thus 
 we see that among the facts which are not open to intro- 
 spection but are of importance in explaining consciousness 
 are the processes which go on in the organs of sense and 
 in other parts of the nervous system. One cannot introspect 
 brain processes, but much light has been thrown on the way 
 in which men think by a study of both the structure and 
 action of the brain. 
 
 Studies of behavior. Another type of indirect or non- 
 introspective investigation which has of late been culti- 
 vated with very great advantage to psychology deals with 
 the facts of human and animal behavior. Here, as in the 
 examination of the nervous activities, it is possible to dis- 
 cover certain stages of development and to relate these to 
 the well-recognized general fact that there are progressive 
 stages of intelligence in the animal kingdom. 
 
 If these and other modes of indirect study of mental life 
 are judiciously added to introspective observations of one's 
 
6 PSYCHOLOGY 
 
 own conscious processes, psychology loses nothing of its 
 directness, and it gains much in breadth. ■ 
 
 Overemphasis of slower forms of mental activity through 
 introspection. ^ further advantage which is secured by rec- 
 ognizing that introspection is not the only possible -method 
 of collecting psychological facts is that the experiences most 
 directly open to introspection are thrown into a truer per- 
 spective by the combination of indirect and direct examina- 
 tion. The student who depends solely on introspection will 
 give the largest share of his attention to that which is in the 
 foreground of consciousness, usually to some complex mental { 
 process which passes slowly across the stage of conscious- ' 
 ness. He will often give undue weight to some single 
 experience because it is so clear, adopting this clear experi- 
 ence as typical, and depending upon it for the explanation 
 of many of the less obvious facts of mental life. For exam- | 
 pie, when one hears a word and stops to consider deliber- 
 ately the conscious process by which he interprets the word, | 
 he is very likely to experience a series of memory images 
 which follow upon the word and give it meaning. Thus, let 
 the reader ask himself what he thinks of when he sees the 
 word '' house." The more carefully he searches in his con- 
 sciousness, the more he becomes aware of trains of memory 
 images. Many psychologists having made this introspective 
 observation set it down as a general fact of all mental life 
 that the process of recognition always consists in the revival 
 of trains of memory images. If the skeptical observer ven- 
 tures to say that he does not find in his ordinary recognition 
 of words such attendant trains of memory images, he is 
 reproved for incomplete introspection. When we come to 
 the problem of recognition of words- in our later discussions, 
 this question will be taken up in detail, and it will be shown 
 that what is needed is not a formula borrowed from the 
 more elaborate, easily introspected case, in which recogni- 
 tion is slow and long drawn out. What is needed is a 
 
SCOPE AND METHODS OF PSYCHOLOGY 7 
 
 formula derived from a study of habit. When we become 
 very famihar with an object we are less and less likely to 
 attach to it trains of images ; we respond to it promptly and 
 skillfully without waiting for a full picture to be developed 
 in the mind. So it is also with words. The more familiar 
 the word, the less the mind delays and pictures its mean- 
 ings. This example shows that psychology must not adopt 
 as its chief bases for explanation the long-draw^n-out mental 
 processes which furnish the most content for introspection. 
 
 Experiment in psychology. When psychology is recog- 
 nized as a broad science, dealing with many facts related 
 to consciousness as well as with consciousness itself, it will 
 be understood why recent studies in this field have made 
 liberal use of experimental methods. Experiment became 
 a conspicuous method in psychology about fifty years ago. 
 Prior to that time the observations of psychologists were 
 limited by the opportunities of personal experience. ^ 
 
 Let us see the advantages of deliberate experimentation 
 by canvassing an example. A psychologist is studying 
 memory. He notes, when he tries to recall objects which 
 he has observed, that there is a certain incompleteness in 
 his mental reproduction and that this incompleteness be- 
 comes increasingly impressive with the passage of time. He 
 will hardly fail to find out by this sort of self-observation 
 much that will help him in describing his processes of 
 memory. Suppose, however, that he wishes to find out 
 with definiteness the law which memory exhibits in its 
 decay, or suppose that he wishes some final decision as to 
 the best way of examining groups of objects in order that 
 he may carry away a complete and permanent memory of 
 them. He wdll find it advantageous for this more complete 
 study to arrange the objects with a view to the questions 
 w^hich he wishes to answer. He will observe the objects 
 during a fixed period, and after a known interval will 
 submit his memory to a definite test. This illustration is 
 
8 PSYCHOLOGY |H 
 
 sufficient to show that there are advantages in the precise | 
 control of the conditions of observations, which is the first j 
 step in experimentation. If, now, the psychologist adds 
 certain aids in the way of apparatus which will make it | 
 easy to record the time intervals and to present the matter 
 to be memorized in absolutely uniform fashion, it will be 
 recognized at once that the more fully developed and pre- 
 cise method of investigatiou leads to a degree of accuracy 
 in ascertaining the facts which is otherwise quite impos- 
 siblerf The experimental method also makes it possible for 
 observers remote from one another to collect their observa- 
 tions under the same conditions, so that they can compare 
 their results and generalize the information which they have 
 gathered/ 
 
 There has been much discussion as to the exact place of 
 experiment in psychology, some holding that it is the only 
 true scientific method, others holding that it is very limited 
 in its application. Those who are most devoted to experi- 
 mental methods have sometimes gone so far as to assert 
 that experimental psychology is a separate discipline. Those 
 who criticize the method point out that the profounder 
 emotions, such as intense sorrow, and the higher forms of 
 abstract thought, such as are involved in a scientific dis- 
 covery, cannot be produced and modified at will. Both 
 extreme positions are to be avoided. Carefully prearranged' 
 observation under controlled conditions,/) wherever this is 
 possible, is the true ideal of scientific psychology. Where 
 experiment is not possible, other forms of observation must 
 and should be employed. 
 
 Explanation at variance with mere observation. It may 
 be well, both for the sake of defining the scope of psychol- 
 ogy and for the purpose of illustrating its methods, to call 
 attention to the fact that this science, like other sciences, 
 frequently brings out in its explanations facts which seem 
 to run counter to direct observation. Thus, before we study 
 
SCOPE AND METHODS OF PSYCHOLOGY 9 
 
 any of the physical sciences, we observe that the surface of 
 the earth about us is apparently flat. As we progress in 
 science we come on facts which are incompatible with the 
 notion that the earth is flat. We note all these observations 
 and compare them, and finally accept as our general scien- 
 tific conclusion the statement that the earth is spherical and 
 not flat, as it seems to ordinary observation. Again, we do 
 not hesitate to accept the dictum of science that the earth is 
 moving at a tremendous rate, although we do not observe 
 the movement directly. These illustrations go to show 
 that scientific conclusions are broader in scope than single 
 observations, and frequently so different from the single 
 observations as to constitute essentially new facts. 
 
 Fig. I. Diagram for use in demonstration of the blind spot (see page 10) 
 
 When we leave physical science where we have learned 
 easily to accept the results of inference, and turn to psy- 
 chology, we do well to remember that earlier generations 
 less trained in the methods of science found it difficult, 
 indeed quite impossible, to substitute inferences about the 
 shape and motion of the earth for the facts of sense ex- 
 perience. We should therefore be prepared by the con- 
 sideration of these analogies to recognize the necessity of 
 comparison and interpretation in our psychology and to 
 overcome our own hesitation in accepting psychological 
 inferences as substitutes for introspective observations. 
 
 A simple mental experience which offers an excellent 
 opportunity for the application of the principle of inference 
 is as follows : Let an observer close one eye and look with 
 the open eye at the printed page before him. He will 
 undoubted^ observe what seems to be an uninterrupted 
 
lO PSYCHOLOGY 
 
 series of impressions coming to him from all parts of the 
 page. This is, however, quite as incomplete a description 
 of the facts as is the description of the earth's surface 
 based upon direct observation. To demxonstrate this, let 
 the observer close or cover the left eye and look steadily 
 with the right eye at the small cross in Fig. i. Now let 
 him move the book backward and forward from seven to 
 eight inches in front of his face until the black circle dis- 
 appears. He will thus discover that a certain part of the 
 page is not yielding an uninterrupted series of impressions. 
 The explanation of the facts here involved cannot be ob- 
 tained through introspective observation, for it depends on 
 the structure of the eye, there being in the sensory surface 
 • of the eye an area that cannot receive impressions. This 
 is the area where the optic nerve leaves the eye. This illus- 
 tration should prepare the student to find in the science of 
 psychology many statements about the nature of his conscious 
 processes which he cannot expect to verify by a simple proc- 
 ess of observation. Observation is indispensable, but the sci- 
 ^/' entific understanding of consciousness requires an elaborate 
 interpretation of all the facts which can be obtained. 
 
 Subdivisions of psychology. ) Psychology as a science 
 dealing in a broad way with conscious processes and with 
 the conditions and results of these processes\ has proved 
 to be most fruitful in its applications. Wherever human 
 nature is to be influenced, whether it be in the writing of 
 an advertisement or in convincing a jury, the psychology of 
 the process is worth understanding. If the study of the 
 process can be made exact through experimentation and 
 comparison, applications will be the safer and more effec- 
 tive. There has been in recent years a vigorous cultivation 
 of psychology in all its possible forms and in all its possible 
 applications. Thus, there is a psychology of animal con- 
 sciousness. There is a psychology of the child's conscious- 
 ness, especially cultivated by those who v/ish to ascertain 
 
SCOPE AND METHODS OF PSYCHOLOGY ii 
 
 the laws of mental development which underlie education. 
 There is a psychology of abnormal human minds known by 
 the special name of psychiatry. There is a psychology of the 
 products of human minds when they act in social groups, 
 as in the development of language, customs, and institutions. 
 This is called social psychology or folk psychology. Certain 
 other lines of subdivision are sometimes drawn. Thus, 
 experimental psychology has sometimes been marked off 
 from other forms of investigation. Physiological psychology 
 has also been treated as a separate science. Finally, it is 
 not uncommon to meet such titles as the psychology of art, 
 or of literature ; the psychology of religion, of the crowd ; 
 and so on through a long list of highly differentiated 
 specialties. 
 
 Some confusion has resulted because of the tendency 
 of psychology to break up into so many minor disciplines. 
 The confusion disappears, however, as soon as one recog- 
 nizes that in methods and subject matter all the special 
 psychologies are merely prarts of the general science. The 
 explanation of the subdivisions is partly historical. As new 
 interests or new methods have asserted themselves, the 
 traditions of the earlier stage of psychology have often 
 resisted the innovation to such a degree that a new disci- 
 pline was for a time necessary to accomplish the develop- 
 ment of the science. In addition to these historical reasons, 
 the breadth of human, interests in the study of experience 
 is so great that the mastery of any single phase of mental 
 life involves a concentration somewhat more pronounced 
 than that which is required in many sections of the physical 
 sciences. 
 
 Summary and definition of psychology. The special de- 
 partments of psychology cannot all be fully treated in a 
 general course, such as that which is to be given in the 
 following chapters. Much can be touched upon only by way 
 of illustration. The general treatment must confine itself to 
 
\y 
 
 12 PSYCHOLOGY ^ 
 
 the establishment of broad principles applicable in greater 
 or less degree to all of the special fields. With this neces- 
 sity of general exposition in mind, the statement with which 
 titiis introductory chapter began may be amplifi^ed as follows : 
 The legitimate function of a course in. general psychology 
 is to consider tlie_^typical processes of mental life with refer- 
 ence to their internal constitution and also with reference to 
 their external conditions ; to examine these processes with 
 the aid of experiments and observations from both the intro- 
 spective and impersonal points of view; and, finally, to relate 
 consciousness to the other phases of life, especially to human 
 and animal behavior, and also to external reality in such a 
 way as to furnish the basis for an adequate understanding 
 not only of individual consciousness but also of the experi- » 
 ence of all conscious beings. \ 
 
 zrr^^efinitions of certain general psychological terms. In this j 
 statemicnt and throughout the chapter the terms ''conscious- \ 
 ness," ''mental life," and "experience" have been used with- 
 out an}/ effort to define them. Complete critical definitions j 
 of these terms presuppose a knowledge of the results of 
 psychological study, for it is the function of psychology to j 
 ascertain the characteristics of consciousness. In the mean- 
 time there is no danger of confusion in the preliminary use 
 of the terms. Consciousness is what each one of us has 
 when he sees and hears, when he feels pleasure or sorrow, 
 when he imagines or reasons, or decides to pursue a line of 
 action. Experience is a general word which may conven- 
 iently be used to cover the same group of facts. Stones do 
 not experience impressions or emotions. Man, on the other 
 hand, lives in a world of experiences. His inner life is not 
 made up of objects, but of experiences of objects. When- 
 ever we think, or remember, or try to understand an object 
 presented to the senses, we have an experience. As pointed 
 out in the discussion of introspectioii>_cQnscious processes 
 may be distinguished from other facts by the possibility of 
 
SCOPE AND METHODS OF PSYCHOLOGY 13 
 
 r ^ . . 
 
 self-observation or introspection, by which method alone 
 
 these conscious facts can be directly observed, j Facts of 
 external reality are open to general observation by many 
 different individuals ; conscious experiences are purely per- 
 sonal, open to introspective observation only^We sometimes 
 express the contrast between the facts of conscious experi- 
 ence and the facts of external reality by the use of the terms 
 ''subjective" and ''objective." Whatever belongs exclusively 
 to the world of experience is called subjective. Thus, ideas 
 and feelings are subjective. The facts with which physics 
 and chemistry deal are not exclusively subjective ; they have 
 objective, external characteristics. Indeed, physics and chem- 
 istry are interested in facts only in so far as they are objec- 
 tive. For these natural sciences the subjective ideas of the 
 individual physicist or chemist are merely the means to an 
 end, which end is the intelligent comprehension of the ob- 
 jective world, frhe same antithesis which is expressed by 
 the terms " subjective " and " objective " is expressed by the 
 terms "psychical facts" and "physical facts." vThe former 
 are the directly known conscious processes ; the latter are 
 the facts of the external world as known through the senses 
 and as studied in the objective sciences. MThese remarks on 
 the various terms which are used in defining the sphere of 
 psychology serve to indicate, in a sufficiently unambiguous 
 way, the direction in which our studies must turn. 
 
CHAPTER II 
 
 THE BODILY CONDITIONS OF BEHAVIOR 
 AND EXPERIENCE 
 
 The introspective approach. There are two lines of pro- 
 cedure which may be adopted in the study of mental proc- 
 esses. On the one hand, we can begin with the description 
 of some personal experience and from this central fact move 
 outward until we arrive at a full explanation of all the causes 
 and conditions of this experience. Thus, when I try to re- 
 member the name of a person whom. I met some time ago, 
 I find that I can recall the vague general fact that it was 
 a short name, beginning with the letter '' E," but it requires 
 time and effort to fill in the rest. The questions which im- 
 mediately arise are such as these : Where is the storehouse 
 in which these memories were locked up ? Why did one 
 part of the name drop away and another part persist ? What 
 kind of effort is necessary to bring out the missing part ? 
 Evidently it will be necessary, before these questions can 
 be answered, to go outside of immediate consciousness. 
 
 Indirect method of approach to psychological facts. The 
 second line of procedure is the reverse of that just de- 
 scribed. We can approach personal experience from without, 
 reviewing briefly the conditions which make such experi- 
 ence possible and gradually coming to the particular facts 
 which at this moment fiJl the observer's mind. This mode 
 of taking up the study has the disadvantage of leaving 
 the student with the impression that psychology is very 
 remote from his inner experiences. On the other hand, it 
 has the advantage of supplying him from the first with a 
 
 14 
 
BODILY CONDITIONS 15 
 
 body of facts which he is not able to contribute out of his 
 direct observation of himself. Some patience will be required 
 in coming thus indirectly to the study of mental processes, 
 and the student will need to keep in thought, with very little 
 aid from the text, the goal toward which the preliminary 
 study is leading. 
 
 The indirect method is the one with which we shall be- 
 gin. We shall take up, first, the facts of animal behavior 
 and nervous organization and shall thus lay the foundations 
 for an explanation of the facts of personal experience. Later 
 we shall review the facts of consciousness itself in the light 
 of this preliminary indirect study. 
 
 Characteristics of unicellular animals. Our method car- 
 ries us back to the most primitive forms of animal life. 
 Here we find minute microscopic beings whose whole body 
 consists of a single cell. This cell is made up of a mass 
 of living tissue known as protoplasm. Such a unicellular 
 animal is capable of moving about by contracting its tissue ; 
 it is capable of reproducing itself by cell division ; it is capa- 
 ble of digesting food and throwing out waste matter ; and, 
 finally, it is irritable when acted upon by external forces. 
 When the student examines life reduced to the low terms 
 which are exhibited in a unicellular animal, he realizes 
 more fully than he is likely to realize when examining 
 higher forms how thoroughly interdependent are all the 
 phases of an animal's life. Consider how impossible life 
 would be without the new supply of energy which comes 
 through digestion ; , how limited in scope life would be with- 
 out movement to bring the animal to new sources of food 
 and carry it out of danger, or without cell division to in- 
 crease the number of members in the species ; and how 
 utterly out of contact with the rest of the world the indi- 
 vidual would be without irritability. The fact that all these 
 functions appear in the simplest unicellular forms shows 
 how fundamental they are. 
 
i6 
 
 PSYCHOLOGY 
 
 Simplest types of behavior. The only facts on which we 
 can base a judgment with regard to the inner processes in 
 such an animal are the facts of behavior. These appear to 
 be very simple. The animal has three forms of movement. 
 It swims forward and takes in food. If it encounters a 
 stimulus which is unfavorable, such as heat or acid, it darts 
 backward and swings around in a direction which takes its 
 mouth opening away from the stimulus. Fig. 2 shows a 
 
 series of movements as exe- 
 cuted by such an animal. The 
 figure represents one end of 
 a microscope slide which is 
 heated at the upper edge. 
 A unicellular organism, Oxyt- 
 richa, in the position i is 
 reached by the heat coming 
 from the upper part of the 
 slide. The animal reacts by 
 turning to the right (position 
 2). This intensifies the exci- 
 tation caused by the heat, and 
 the animal backs to position 3. 
 It then turns (position 4) and 
 swims forward (position 5), 
 again encountering the heat. 
 It then darts back (position 6), turns (position 7), and swims 
 forward until it comes against the wall of the trough (posi- 
 tion 8). It then reacts as before, by backing (positions 8-9), 
 and turning to the right (positions 9-10). This type of 
 reaction continues as long as its movements carry it either 
 against the wall or into the heated region. When it finally 
 gets away, as it must in time if it continues its reactions, 
 it swims forward, taking food as it did before disturbed. 
 Thus we see that there are in the lowest animals very limited 
 possibilities of behavior. . ^ 
 
 Fig. 2. Movements of a unicellular 
 animal. (After Jennings) 
 
BODILY CONDITIONS 17 
 
 Consciousness no more complex than behavior. This 
 meager repertoire of behavior betokens a relatively undif- 
 ferentiated inner life. Yet even this animal is influenced 
 by the impressions made upon it by the outer world. We 
 may think of the heat as setting up a commotion among 
 the molecules which make up the body, and this inner 
 commotion results in a recoil. We distinguish between the 
 irritability of the animal and its power of movement, but in 
 reality these two functions are one. The animal recoils 
 because it is internally aroused by the heat. Once the 
 extraordinary condition is removed, the animal begins to 
 exhibit its more peaceful form of behavior, namely, that 
 of swimming forward, this evidently being the natural ex- 
 pression of its calmer inner condition. 
 
 It is hardly possible for us to imagine, in terms of our 
 own consciousness, what must be the inner experience of 
 such an animal, if, indeed, we have any right to think of 
 it as having experience. Certainly a unicellular animal can 
 have discriminations only of the grossest sort. When all is 
 well and the animal is swimming forward and taking food, 
 the inner state must be one of well-being. When the shock 
 of a strong stimulus comes, there must be a kind of vague 
 inner excitement. The two inner states probably differ just 
 in the degree in which the forms of behavior differ. 
 
 Behavior more limited than sensitivity. If we study such 
 animals with respect to irritability, we find that they respond 
 to various forms of external energy. Thus, if light falls on 
 the water, some species will collect in the darkness, others 
 in the light, in such numbers as to indicate clearly in either 
 case that they are affected by the light. Again, pressure 
 due to contact with external objects, as shown above," and 
 also vibrations of the water are effective in producing more 
 or less intense movements. Acids or other strange chemical 
 substances in the water will produce reactions similar to 
 those called out by heat. In all these cases the animal 
 
i8 
 
 PSYCHOLOGY 
 
 exhibits only a few fixed forms of reaction. Our inference 
 is that the inner processes aroused by all the different 
 forms of energy are alike. The further inference is that the 
 animal discriminates between that which calls for forward 
 
 movement and that which calls for 
 withdrawal, but is not able to make 
 any finer discriminations. 
 
 The study of unicellular organ- 
 isms leaves us, then, with four 
 important general facts on which 
 to base our study. Irritability is 
 a fundamental function of even 
 the lowest forms of protoplasm ; 
 it is at first very little differenti- 
 ated ; it is the function which 
 guides the animal in its responses 
 to its environment ; and, finally, 
 the description of behavior is a 
 very direct means of arriving at 
 an understanding of the inner 
 processes of irritability. 
 
 Specialization of cell structures 
 and functions in higher animals. 
 Turning: now from the unicellular 
 
 Fig. 3. The hydra 
 
 The figure shows a section through 
 the body and exhibits the two cellu- 
 lar layers with a neutral layer 
 between. The general body cavity 
 G is lined by cells which are 
 devoted entirely to the special 
 
 function of digestion (the mouth 
 
 opening is at M). R, R, R, R animal to a form somevv^hat higher 
 
 are the reproduction cells. The j^ ^j^^ ^^^j^ ^^ ^^^ ^j^^^ StrUCtur- 
 outer wall of the body is made ^ 
 
 up of muscle cells and specialized ally the morc highly dcvcloped 
 sensitive cells. T T T are the ^^imals are characterized by the 
 
 tentacles. (Adapted from Haller) ^ ^ ^ ■' 
 
 fact that their bodies, instead of 
 consisting of a single cell, consist of an aggregation of cells ; 
 this we express by the statement that they are multicellular or- 
 ganisms. Fig. 3 represents a section of a simple multicellular 
 animal which lives in fresh water and is known as a hydra. 
 The animal is sack-shaped, with a mouth opening and ten- 
 tacles at its upper end. The figure shows the walls of the 
 
BODILY CONDITIONS 19 
 
 sack-shaped body much magnified. The inner Hning of this 
 wall is made up of a layer of cells which are specialized to per- 
 form the function of digestion. The outer wall is specialized 
 in certain of its cells for the reception and transmission of 
 stimulations, and in other cells for the performance of move- 
 ments. The processes of reproduction are provided for at 
 special points in the body wall as indicated at R, Ry R, R, 
 in Fig. 3. Between the inner and outer layers there is an 
 intermediate layer of tissue, in w^hich cells sometimes appear 
 from one of the primary layers. The intermediate layer is not 
 sufficiently developed to constitute a separate series of organs. 
 The multiplication of cells and specialization of functions 
 here exhibited have advantages familiar to anyone who has 
 observed the analogous fact of division of labor in social 
 organizations. The cells of the body which are set apart for 
 special purposes do not lose the general characteristics which 
 belong to all living protoplasmic cells. For example, all the 
 cells of the body absorb the necessary nutrition to support 
 their individual lives, butthe cells outside of the digestive 
 layer do not take their nutrition from the external world ; 
 they derive it from the digestive cells which alone perform 
 the special function of digesting foreign particles. So also 
 with the function of irritability. This is not lost by the 
 specialized contractile cells and digestive cells ; it is merely 
 reduced in these cells to a very low point and is very highly 
 developed in the specialized sensitive or irritable cells, so 
 that the movement cells or muscle cells and all other parts 
 of the body come ultimately to receive their impressions 
 from the outer world, not directly, but through the neural 
 or sensory cells. The neural cells or nerve cells are special- 
 ized cells Vv^hich take over the function of irritability. They 
 are placed in the outer body wall, where they are in the 
 most favorable position to be acted upon by external forces 
 or stimuli, as forms of energy which affect the nervous sys- 
 tem are technically called. They develop a more complex 
 
20 
 
 PSYCHOLOGY 
 
 I 
 
 chemical structure than the other cells of the body, so that 
 they are more easily set in action by external forces. They ^ 
 are, accordingly, highly important, but by no means inde- 
 pendent factors in the organic economy. They are developed, 
 not for some remote and separate life ol mere irritability or 
 sensitivity, but as essential parts of the developing organism, 
 acting as paths through which external forces enter the body 
 and cause inner states which will adapt the animal in its activ- 
 ities to the world in which it lives. 
 Even in the simple organism 
 under consideration, the process 
 of specialization has advanced so 
 far that there begin to appear 
 various classes of neural or irri- 
 table cells, each serving a special 
 function. Certain of these cells 
 serve the direct function of receiv- 
 ing impressions from the outer 
 Fig. 4. Much-enlarged section world, and are known as sensory 
 
 of a muscle cell and a sensory ,, - .. , ,1 r 
 
 cell of a hydra, together with ^ells, while Others scrve the func- 
 the connecting cells which he tion of transmitting the impulse to 
 
 the muscle cells. Fig. 4 shows a 
 much-enlarged section of the outer 
 body wall of a hydra. M is a mus- 
 cle cell, heavy and elongated to 
 make more effective the contractile 
 function. 5 is a sensory cell which receives impressions. 
 C, C, C, C are intermediate transmitting cells, and F, together 
 with the other fibers shown, carry the impression through C 
 from 5 to M. 
 
 Specialized nervous processes. The process which goes 
 on in the neural cells may be described as follows : Some 
 form of external energy acts upon the cells. The external 
 energy, as noted above, is called a stimulus. This sets up 
 a chemical process in the cell which is known as a process 
 
 between them 
 
 M, muscle cell ; -S, sensory cell ; 
 C, intermediate, cells ; /% fiber 
 connecting the sensory cells with 
 the central cells. (Adapted from 
 Haller) 
 
BODILY CONDITIONS 21 
 
 of excitation or a stimulation. The process of excitation 
 liberates energy which was stored up in the cell. This 
 liberated energy is transmitted to other cells in the body, 
 either to the secondary transmitting neural cells, C, C, or to 
 the active contractile cells such as M, This current of 
 nervous energy has been compared to an electric current. 
 It is, however, much slower than an electric current, its rate 
 of transmission being in the higher animals about one 
 hundred meters per second or less. We do not know its 
 exact character, but probably it is more like the succession 
 of combustions which takes place along the line of a fuse 
 of gunpowder. Our ignorance of the exact nature of the 
 nervous current need not delay the discussion, however, for 
 we shall find that the importance of nervous currents 
 for our further study depends upon their paths of trans- 
 mission rather than on their chemical nature. The path of 
 transmission will be determined primarily by the direction 
 and connections of the fibers which unite the cell in which 
 a given excitation originated with other parts of the body ; 
 secondarily, the path of transmission will depend on the 
 fatigued or unfatigued condition of the cells and on the 
 other currents of energy which are flowing through the system 
 at the same time. All these complex possibilities may be 
 summed up in the statement that in its transmission through 
 the neural organs every nervous excitation is directed and 
 is combined with other impulses, and is ultimately determined 
 in its effects by its path of transmission to the muscles or 
 glands and by its relation to other impulses. Furthermore, 
 as soon as it is recognized that nervous impulses consist in 
 currents of energy which have been liberated by the stimulus, 
 it will be recognized that every nervous current must pro- 
 duce some effect before it is dissipated ; for a current of 
 energy must do some work — it cannot disappear. The 
 effects produced by nervous impulses are of two kinds. 
 First, the energy may be absorbed in the course of its 
 
22 PSYCHOLOGY 
 
 transmission, in which case it will produce changes in the 
 condition of the nervous tissue, thus contributing to the 
 modification of the structure of that tissue. Second, it may 
 be carried to the natural outlet of all nervous excitations, 
 namely, the active organs of the body, where it will produce 
 some form of behavior. If it contributes to changes in 
 structure, these changes in structure will ultimately influ- 
 ence new incoming impulses which are on the way to the 
 active organs. We may therefore say that, directly or in- 
 directly, all incoming nervous impulses are transmitted to 
 the active organs of the body after being more or less 
 completely redirected or partially used to produce structural 
 changes in the nervous organs. 
 
 Nervous processes of three distinct types. The range of 
 nervous processes possible in the simple structures of a 
 hydra is' extremely limited ; for this very reason the funda- 
 mental characteristics of nervous processes are all the more 
 apparent. We can distinguish clearly the first step which 
 is the reception of the external stimulus.' This first step 
 is commonly described as a sensory nervous process. The 
 cell on which the stimulus acts is a receiving cell. The in- 
 termediate cells placed between the receiving cell and the 
 muscle are called transmitting cells or central cells. The 
 fibers passing from the central cells to the muscle or gland 
 are motor fibers. It will be seen that the) sensory,) central, 
 and'^motor processes cannot be sharply distinguished from 
 each other ; they are all phases of a single continuous 
 process, the end of which is always some active process in 
 the muscles ; but for purposes of scientific explanation it is 
 necessary to distinguish them as three distinct types. 
 
 Behavior varied and much more complex. If we contrast 
 the hydra with the unicellular organism studied in earlier para- 
 graphs, we are at once impressed by the fact that the hydra 
 has a greater variety of forms of behavior. To be sure, all 
 these forms of behavior belong under two fundamental types. 
 
BODILY CONDITIONS 23 
 
 namely, that of moving forward to capture food and that of 
 withdrawing from danger. But each of these fundamental 
 forms of action has been developed so that it is more 
 elaborate and varied than it was in the unicellular animal. 
 Thus the tentacles move in such a way as to sweep food 
 into the mouth, and they contract in the presence of 
 unfavorable stimuli, even when the body as a whole is not 
 in full action. The body moves sideways, now in one 
 direction, now in another. In short, the more complex 
 animal is characterized by an increasing variety of action. 
 
 Not only so, but an action often consists of a series of 
 related movements, making a complex chain of acts, all 
 directed toward a single end. The body, for example, 
 comes in contact with a piece of food. The animal swings 
 around, the tentacles seize the particle, sweep it into the 
 mouth, and the inner digestive canal closes in on it and 
 begins its ingestion. Such a chain of cooperating acts 
 shows that a high level of evolution of behavior has been 
 reached where single elements of behavior are united into 
 complex coordinations. 
 
 From this point on we shall dwell chiefly on the structural 
 growth of the nervous system, but the statements made 
 regarding the behavior of hydra should be thought of as 
 repeated and even as amplified to correspond to each 
 progressive complication of nervous structures. 
 
 Progressive evolution in both structure and behavior. 
 When we turn from the hydra to the higher forms of life, 
 we find that the multiplication and specialization of cells go 
 on to the highest degree, producing in the animals at the 
 upper end of the scale a variety of forms of sensitivity and 
 of behavior which culminate in such capacities as those 
 exhibited in man. 
 
 Centralized nervous system. We must confine our survey 
 to a few of the major facts in this process of evolution. As 
 we ascend the. scale, there is a grouping of the central cells 
 
24 
 
 PSYCHOLOGY 
 
 into complex organs and, second, a differentiation of the 
 receptive or sensory cells resulting in the production of 
 special organs for the reception of a great variety of stimuli 
 such as light, sound, tastes, odors, and other forms of 
 energy. These two types of development may advantageously 
 be considered in succession. For the remainder of this 
 chapter, the differentiation of the sense organs will be 
 
 passed over and the evolu- 
 tion of the central organs 
 will be briefly sketched. 
 
 The nerve cells of the 
 hydra are scattered diffusely 
 throughout the body wall ; 
 there is no special part of 
 the body in which the cen- 
 tral cells are massed. The 
 higher animals all have a 
 more or less highly cen- 
 tralized nervous system. A 
 simple type of centralization 
 is seen in the starfish. 
 Fig. 5 shows the general 
 outline of this animal's body 
 and the distribution of the 
 central nervous cells. Each 
 double line represents a 
 group of cells. It will be 
 seen that there is for each arm a central group of cells, to 
 which sensory excitations come from the surface of the body 
 and from which motor impulses go out to the muscles. 
 There is also a central ring which binds together the differ- 
 ent arms and centralizes in a still higher degree the whole 
 animal. This ring is in the neighborhood of the mouth 
 opening, and its function is undoubtedly that of controlling 
 the whole animal in taking food. 
 
 Fig. 5. Outline of a starfish, and nerv- 
 ous system of the same 
 
 Each arm of the starfish is suppHed with 
 a series of nerve cells indicated by the 
 lines passing through the various arms. 
 From these nerve cells, fibers extend to 
 the surface and receive sensory impulses 
 and send out motor impulses. (After Loeb) 
 
BODILY CONDITIONS 
 
 25 
 
 Another type of centralization appears in any one of the 
 segmented animals, such as an insect. Fig. 6 shows such a 
 centralized nervous system. Each segment has its group of 
 central cells, and all the segmental centers are related by 
 connecting fibers to one another and to the highly developed 
 group of cells in the first segments, 
 which are near the mouth opening. 
 
 Coordinating center of the body. 
 The development of a complex cen- 
 tral nervous system is of the high- 
 est importance in animal life. As 
 we have seen, the body cells of 
 the higher animals are specialized. 
 There must be some central con- 
 trolling group of cells or the body 
 would not be able to carry on its 
 manifold functions in a unified and 
 harmonious fashion. The central 
 nerv^ous system is the controlling 
 and unifying organ. The arms of 
 the starfish are made to serve the 
 mouth because the mouth ring of 
 nerve cells is the dominating organ 
 of the body. In the beetle all the 
 organs of locomotion are made to 
 serve the head, which is both the 
 entrance to the alimentary canal and 
 the seat of the important special 
 organs of sense, namely, the eyes and the feelers. The 
 central nervous system reproduces in outline the whole body 
 and is a connecting tract through which stimulations are 
 carried from one organ to the other. 
 
 It is hardly necessary to reiterate the statement made above 
 that this evolution of nervous structures is paralleled by an 
 evolution in behavior. The number of acts of which an insect 
 
 Fig. 6. A stag beetle, show- 
 ing the outline of the body 
 and the distribution of the 
 nerve cells and fibers 
 
 Each segment of the body has 
 a ganglion of cells G, G, G, 
 from which fibers F^ F^ F are 
 distributed to the surface of 
 the body for the reception of 
 stimulations and the distribu- 
 tion of motor impulses. The 
 ganglion in the front section 
 of the body is double and of 
 greater importance than those 
 in the posterior segments 
 
26 « PSYCHOLOGY 
 
 is capable, the complexity of its methods of locomotion, of 
 protection, and of reproduction, — all attest the intimacy of 
 the relation between nervous structure and behavior. 
 
 Complex paths within the nervous system. Not only so, 
 but the central group of nerve cells begins to have certain 
 internal paths which take on the largest significance for the 
 animal's life. The energy which comes in at the sense 
 organ of a beetle sets up through the central nervous system 
 a most complex chain of acts. Think, for example, of such 
 an insect aroused by the smell of food. It first flies to the 
 spot, guided by the increasing intensity of the odor ; it lights 
 on the food and then seizes it. In such a series of acts 
 the nervous system has acted in the most complicated way to 
 control and keep in action the various muscles of the body 
 in the interests of the whole organism which is dependent 
 for its life on its ability to find food and absorb it. 
 
 Such considerations lead us to think of the nervous system 
 itself as a complex organ made up of dominant centers and 
 secondary centers with paths running between them. Our 
 later study will fully justify such a conception. 
 
 When the nervous system reaches this stage of organiza- 
 tion, many of its inner paths and centers are determined by 
 the animal's inheritance. Just as a starfish inherits arms and 
 a mouth from its race, and a beetle inherits legs and wings, 
 so each animal inherits certain paths through its central 
 nervous system. These inherited paths play a large part in 
 controlling the life of the individual animal. The insect takes 
 a certain type of food because its inherited sensory cells 
 respond in a certain definite way to certain odors. Other 
 special activities, such as depositing eggs and special modes 
 of flight designed to carry the animal away from enemies, 
 are due also to the organized tracts which run through the 
 nervous system. Indeed, it appears in the study of insects 
 and animals at the lower levels of evolution that practically all 
 their modes of behavior are determined through inheritance. 
 
BODILY CONDITIONS 27 
 
 Experience comparable to the lower forms of human 
 experience. If we try to guess what are the experiences of 
 such an animal, we must not draw on our own experiences 
 of meditation and deHberation. Dehberate casting about in 
 thought for a course of action is far from characteristic of an 
 insect. The analogy which we should borrow from human 
 experience is the analogy of a fully organized habit or, better, 
 the analogy of one of our own inherited modes of action, 
 such as that exhibited in the winking of the eye or jerking 
 the head aside when an object moves rapidly toward the face, 
 threatening to strike it. Conscious experience is made up 
 in such cases, not of clearly defined knowledge of the thing 
 which gives rise to the experience, but rather of a vague 
 excitement, followed by unrest when the instinctive winking 
 or dodging does not adequately meet the requirements of 
 the situation, and by satisfaction when the activity proves 
 sufficient. 
 
 Differentiation of vertebrate central nervous system. 
 Passing by long steps up the scale of life, we may next 
 consider the nervous system of one of the lower vertebrates. 
 Here we find that the centralized organization has gone be- 
 yond that seen in the insects, but it is yet relatively simple. 
 Fig. 7 shows the general form of the frog's nervous 
 system looked at from above. In all of the vertebrates the 
 nervous system is incased in the bones of the vertebral 
 column and skull, so that the view here presented shows 
 the appearance of the nervous organs after the bones and 
 muscles and skin which cover these organs in the normal 
 animal have been removed. The frog's nervous system may 
 be roughly divided into two main sections. The first part 
 lying behind the cerebellum consists of the long cylindrical 
 spinal cord with the medulla, which is essentially an enlarge- 
 ment at the upper end of the cord. The cord and medulla 
 are directly connected with the surface of the body by means 
 of a great number of fibers. The incoming sensory impulses 
 
28 
 
 PSYCHOLOGY 
 
 F 
 
 from the skin are received through certain of these fibers, 
 and motor impulses are distributed to the muscles through 
 
 others. There are many cells 
 in the cord and medulla, their 
 chief function being to form 
 links of connection between 
 the incoming sensory fibers 
 and the outgoing motor fibers. 
 If the cord and medulla are 
 separated from the higher cen- 
 ters by a cut just below the 
 cerebellum, the animal con- 
 tinues to live and is capable 
 of certain simple responses to 
 sensory stimuli, the only depar- 
 ture from the normal being that 
 activities called out by stimuli 
 and muscles and protecting bone show a machinc-like regularity. 
 
 were removed t-i •r j r 'j • 
 
 Ihus, II a drop oi acid is 
 
 A, spinal cord with some of the nerve 
 fibers which extend from this organ 
 to the surface of the body (in the 
 posterior region a plexus of fibers 
 extends to each of the posterior ex- 
 tremities ; in the anterior region^ a 
 plexus extends to each of the anterior 
 extremities) ; B, medulla ; C, cerebel- 
 lum ; D, optic lobes, which are con- 
 nected with the eyes by optic fibers that 
 pass underneath the brain ; E, optic 
 thalami ; F, cerebral hemisphere. The 
 anterior portions of the hemispheres 
 constitute what are known as the olfac- 
 tory lobes. These lobes are directly 
 connected by means of the fibers shown 
 in the figure with the olfactory region. 
 Many of the nerve fibers which extend 
 from the medulla to the surface of the 
 body are omitted in this drawing 
 
 Fig. 7. The nervous system of a 
 frog as it would appear if the skin 
 
 applied to the skin of the frog's 
 trunk, the nearest leg brushes 
 off the excited spot. The acid 
 sets up a sensory process ; this 
 travels up to the cord and 
 there passes through certain 
 central cells and is sent back 
 along motor fibers to the mus- 
 cles. The whole process is 
 like that described a few pages 
 back as taking place in the 
 hydra. There is no evidence 
 that a frog having its spinal 
 cord severed from the higher 
 centers has any ability to carry on the higher processes of 
 discriminating reaction which involve intelligence. 
 
BODILY CONDITIONS 29 
 
 If the frog is normal, — that is, if the connection be- 
 tween, the spinal cord and the higher centers is intact, — the 
 impulses received by the cord, in addition to circulating 
 through the lower centers, are carried up to the higher 
 centers. Here they are influenced by the action of higher 
 centers. 
 
 Two types of higher centers : first, higher sensory centers ; 
 second, indirect centers. The centers above the cord and 
 medulla, which constitute the higher group of structures in 
 the frog's central nervous system, are of two kinds. First, 
 there are certain sensory centers, namely, the large optic 
 lobes and the olfactory lobes. These connect respectively 
 with the eyes and nose of the frog and receive sensory 
 impulses from these higher senses. The large size and 
 forward position of these two centers indicate the impor- 
 tance of the functions which they perform in the animal's 
 life. Especially, the large size of the optic lobes is directly 
 related to the fact that the frog uses its sense of sight in 
 capturing the insects on which it subsists. Second, there 
 are, as will be seen from an examination of the figure, 
 certain parts of the upper brain which have no direct 
 connection with the surface of the body. Thus there are 
 large masses of tissue in the cerebrum and in the optic 
 thalami which lie between the olfactory and optic centers. 
 These are higher centers, where the processes which 
 are received in the sensory centers may flow together 
 and fuse into higher and more complex forms of nervous 
 activity. 
 
 The meaning of these higher centers will be understood 
 if we use an analogy. In a large business concern there are 
 minor clerks and managers who attend to all the immediate 
 details. These lower officers are in contact with the outer 
 world. Far removed from such direct contact, in a quiet, 
 central office is a central manager, to whom the minor offi- 
 cers report when they need to bring other workers in the 
 
30 PSYCHOLOGY 
 
 establishment into cooperation or when they have problems 
 requiring greater deliberation and broader views than they 
 can command. 
 
 The indirect nervous centers are fusion centers or associa- 
 tion centers, to which all the lower centers refer their activi- 
 ties when these activities need a higher coordination. There 
 is thus developed within the nervous system a higher level, 
 which is of superior importance. 
 
 Large indirect centers characteristic of highest animals. 
 If we follow the evolution of the nervous system from the 
 frog up to man, the most impressive fact is that these in- 
 direct centers are the ones which show marked enlarge- 
 ment. A study of Fig. 8 will bring out the facts. A, 
 in the upper left-hand corner of this plate, shows the 
 brain of a codfish. At the right is the cord, enlarging 
 under the cerebellum into the medulla. The cerebellum is 
 much more fully developed than in the case of the frog. 
 This is one of the indirect centers referred to in the open- 
 ing sentence of this paragraph. The midbrain, which is 
 the optical center, is very large, and at the extreme left 
 the olfactory region can be seen. The cerebrum consists 
 in this case solely of the corpus striatum, an organ which 
 in the higher brains is subordinated to the cortex of the 
 cerebrum. 
 
 By in the plate, needs no special discussion. The in- 
 crease in relative importance of the cerebrum is unmistak- 
 able. In C the preponderance of the indirect centers is 
 even more evident. The surface of the cerebellum is folded 
 so as to make more room at the surface of this organ for 
 the nerve cells. 
 
 Finally, D shows the final type of brain which is char- 
 acteristic of the highest animals. The cerebrum literally 
 covers all the forward organs. It is folded or convoluted on 
 its surface for the same reason as the cerebellum. The 
 cord, medulla, and other lower organs are present and, 
 
BODILY CONDITIONS 
 
 31 
 
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 considering the size of the animal's body, are organs of about 
 the same importance as in the frog or codfish. The cerebrum 
 and, to a less extent, the cerebellum are the organs which 
 attract attention. The higher functions of the dog both in 
 behavior and in the realm of intelligence must be related to 
 
32 PSYCHOLOGY 
 
 the enormous development of his cerebrum. It is in the 
 indirect centers of the cerebrum that those nervous processes 
 take place which condition intelligence and the correspond- 
 ing types of behavior. In the lower animals a sensory im- 
 pulse passes very directly through a relatively small amount 
 of central tissue to the organs of action. In these lower 
 animals, also, most of the paths of transmission are in- 
 herited. In the higher forms, on the other hand, there is a 
 vast amount of tissue, and the sensory impulse may be greatly 
 modified by traveling along a complicated route before it is 
 discharged into the muscles. In the course of this long 
 journey it may be united with many sensory impulses from 
 other sources, so that the final action is the resultant of 
 many cooperating impulses. 
 
 Traces of past impressions also present. Not only so, 
 but this complex tissue becomes a storehouse for a great 
 \/ variety of changes in structure which result from the recep- 
 tion of sensory impressions and the sending out of motor 
 impulses. The phrase ''tablets of memory" begins to take 
 on a very vivid meaning to the student of brain anatomy. 
 Here in the central masses of tissue to which the rest of 
 the nervous system reports are the real seats of organized 
 personal life, the records of which are deposited in the 
 course of experience. 
 
 Meaning of evolution of complex organisms. The pro- 
 found significance of this increasing inner complexity of the 
 nervous system can be understood only when we recognize 
 that increased inner complexity has always been the outcome 
 of animal evolution in every organ and every function. 
 
 Let us study, for example, the evolution of those organs 
 of the body that produce the temperature which is charac- 
 teristic of the higher, so-called warm-blooded, animals. The 
 simple organism is without the power of generating a con- 
 stant inner temperature and is therefore utterly dependent 
 for its body temperature on the environment. As a result. 
 
 rJ 
 
BODILY CONDITIONS 33 
 
 such an animal cannot carry on vigorous life in the cold. 
 The complex organism, on the other hand, has purchased 
 self-sufficiency in matters of temperature by the evolution 
 of a complex set of temperature-producing organs. The 
 range of such an organism's life is consequently enormously 
 increased. 
 
 Another striking example of increasing self-sufficiency is 
 furnished by studies of the reproductive processes. In the 
 simple forms of life the offspring is exposed very early to 
 the mercies of the environment. The parent organism has 
 no adequate means of protecting the young. Gradually the 
 parent grows more complex and in the same degree better 
 able to protect the offspring. There is an increase in the 
 food supply deposited with the egg and an increase in pro- 
 tective devices. The goal of this line of evolution is reached 
 when the parent becomes sufficiently complex in structure 
 to provide for the elaborate development of the offspring 
 within the parent organism. The whole process of evolution 
 is here seen to lead in the direction of self-sufficiency on 
 the part of the organism. Instead of depending on the 
 chances of environmental conditions, the organism builds 
 up an environment of its own within which its reproductive 
 processes may be brought to a high degree of completion 
 before exposing the product to the external world. 
 
 Every organ of the complex animal bears witness to the 
 truth that inner self-sufficiency is the end toward which 
 organic evolution has been progressing. There are organs 
 for the storing of energy, so that the individual shall be 
 relatively free from the necessity of securing immediate 
 nutrition. There are organs for the secretions of chemical 
 reagents which shall convert the raw material used as food 
 into proper ingredients for the building up of body tissues. 
 Organisms have always exhibited in their higher forms 
 organs of mobility, which make them free to move at their 
 own initiative. 
 
34 PSYCHOLOGY 
 
 In all these cases the obvious significance of increasing 
 complexity is increasing autonomy of the individual. The 
 process of evolution has resulted in a more stable set of 
 inner conditions, which make it possible for the vital proc- 
 \y' esses to go on without interruption or hazard from fluctua- 
 tions in the outer world. 
 
 Inner organization essential to highest forms of personal 
 behavior. The meaning of a complex nervous system thus 
 becomes clear. Nature is evolving an organism in which 
 inner processes are to be of prime importance. Impressions 
 must be received fromx the outer world, but the important 
 question now is. What will be done with these impressions 
 in the inner nervous system, where the impression is distrib- 
 uted and combined with other impressions and with traces 
 of past impressions } . 
 
 We are thus brought to the point where we realize the 
 meaning of the sharp antithesis between inner personality 
 and sensory impressions. Two men receive the same im- 
 pression ; to one it means much, to the other little. The 
 reason for the difference is that in one case there is a highly 
 organized central response, in the other there is no such 
 response. 
 
 Our later chapters will have much to say about the inner 
 organization of the nervous system. In the meantime, it 
 should be kept in mind that behavior runs parallel with this 
 highest evolution. Man is not only complex in his inner 
 nervous life, but he is complex in his acts. When one 
 thinks of the complexity of speech or' of the forms of skill 
 exhibited in the arts, one realizes that behavior and nervous 
 organization go hand in hand at the highest levels of life 
 as well as at the lower levels, which were studied in the 
 opening paragraphs of this chapter. 
 
 Characteristics of behavior of higher animals. The pur- 
 poses of our present discussion will be best served, there- 
 fore, by reviewing briefly some of the characteristics of the 
 
BODILY CONDITIONS 35 
 
 behavior of the higher animals. First, the variety of move- 
 ments is vastly increased. Up to a certain point in animal 
 evolution the number of organs of movement, of limbs and 
 oral muscles for example, increases to meet the increasing 
 needs of the animal ; but ultimately a point is reached where 
 development of movement goes forward without any corre- 
 sponding development of new limbs or muscles. This later 
 stage is characterized by the development of nervous struc- 
 tures which make it possible to use the given muscles in a 
 greater variety of combinations. Thus a skilled artisan de- 
 pends for his perfected movements, not on the development 
 of new arm muscles or finger muscles, but on the develop- 
 ment of finer coordinations of those muscles which all human 
 beings possess. 
 
 A second striking fact of behavior which parallels the 
 development of complex nervous centers is that slight stim- 
 uli may set up the m^ost elaborate processes. The value of 
 the stim.ulus in such a case is determined not by the in- 
 tensity or quality whichjt has in itself but by the complex 
 organization which it arouses to action. Conversely, a strong 
 stimulus may be absorbed in the elaborate organization and 
 produce no immediate effect. These statements can be illus- 
 trated by the behavior of a frog under the two kinds of 
 conditions discussed above, namely, when the animal has 
 been deprived of its higher centers and when its nervous 
 system is intact. If a stimulus is applied under the former 
 and simpler conditions, a response will follow immediately 
 with mechanical regularity. This response wall be of a very 
 simple and direct type, usually consisting in a movement of 
 one of the legs up to the point of irritation. In a second 
 case we may apply the same stimulus to a frog in which the 
 cord and medulla are connected with the higher centers. 
 The reaction in this case wall be of an entirely different 
 character. It will usually not come immediately, and its 
 form will depend on a great variety of complex conditions. 
 
36 PSYCHOLOGY M 
 
 Thus, the frog may jump away, it may croak, or there may be 
 a complete absence of apparent reaction. If such results as 
 these appear in so simple an animal as a frog, the complexity 
 of possible organization in a human being can be imagined. 
 Third, as perhaps the most important result of the de- 
 velopment of indirect nervous centers, is the fact that the 
 impressions and activities which appear in the course of 
 individual life are stored up and enter very largely into 
 the determination of nervous organization. As pointed out 
 above, the lower direct centers are in the main determined 
 in structure by heredity ; the higher centers, on the other 
 hand, are found to be undeveloped at birth, so that the 
 stimuli which act upon the individual find at the beginning 
 of life a mass of undeveloped tracts through which they 
 may be transmitted. It has long been recognized that the 
 infancy of all the higher animals, especially human infancy, 
 is very much longer than the infancy of the lower forms. 
 The reason for this appears as soon as we recognize that 
 the higher centers of the nervous system are not mapped 
 out by heredity and require time to mature. 
 
 SUMMARY 
 
 The statements which have been made throughout the chapter 
 may be summarized in a table. This table shows the steady growth 
 in the complexity of animal structure and animal behavior and 
 opens the way for an understanding of the place of consciousness 
 in the economy of life. 
 
 
 Lowest Forms 
 
 Hydra 
 
 Intermediate 
 Forms 
 
 Highest Forms 
 
 Body 
 
 Unicellular 
 
 Very simple 
 multicellular 
 
 Increasingly 
 complex 
 
 Most complex 
 
 Nervous 
 System 
 
 None 
 
 Specialized 
 cells diffused 
 through wall 
 of body 
 
 Organized 
 and central- 
 ized 
 
 Characterized 
 by the great 
 development 
 of indirect 
 centers 
 
BODILY CONDITIONS 
 
 37 
 
 
 Lowest Forms 
 
 Hydra 
 
 Intermediate 
 Forms 
 
 Highest Forms 
 
 Organs 
 of Sense 
 
 None 
 
 Very little, if 
 indeed at all, 
 differentiated 
 
 Increasingly 
 differentiated 
 
 Further dif- 
 ferentiated, 
 reaching com- 
 plete differen- 
 tiation (see 
 later chapter) 
 
 Behavior 
 
 Simplest 
 
 Simple 
 
 Grows more 
 and more 
 
 complex 
 
 Most complex 
 
 
 ^, limited in 
 variety 
 
 a, increasing 
 in variety 
 as compared 
 with unicellu- 
 lar forms 
 
 a^ shows va- 
 riety of in- 
 stinctive acts 
 
 a^ specialized 
 movements of 
 great variety 
 
 
 b^ made up of 
 single acts 
 
 b^ made up of 
 simple series 
 
 b^ made up of 
 combinations 
 of factors 
 
 ^, long coordi- 
 nated trains 
 
 
 <:, very little 
 modified by 
 
 r, very little 
 modified by 
 
 <:, somewhat 
 modified by 
 
 c^ guided 
 chiefly by 
 
 
 experience 
 
 experience 
 
 experience 
 
 experience 
 
 
 d^ follows 
 very directly 
 on stimulus 
 
 <f, direct, as in 
 
 unicellular 
 
 forms 
 
 (/, for the 
 most part 
 direct, but in 
 higher forms 
 includes indi- 
 rect or mem- 
 ory factors 
 
 d^ chiefly indi- 
 rect, as shown 
 in man in such 
 activity as 
 speech 
 
 Type of 
 
 Something 
 
 Vague feel- 
 
 Possibly vague 
 
 Instinctive 
 
 Experi- 
 ence 
 
 like vague 
 feelings 
 
 1 
 
 ings 
 
 recognition of 
 those objects 
 which call for 
 instinctive re- 
 actions, but 
 chiefly affec- 
 tive ; that is, 
 made up of 
 feeling 
 
 recognitions 
 and feelings 
 present, but 
 overlaid by 
 intelligent 
 consideration 
 
CHAPTER III 
 
 THE HUMAN NERVOUS SYSTEM 
 
 External plan like that of all vertebrates. The structural 
 plan of the human nervous system is the same as that of all 
 
 vertebrates « Fig. 9 shows the out- 
 lines of the whole system. Through 
 the vertebral column runs the cord. 
 This enlarges at the upper end into 
 the medulla. These two organs are, 
 in proportion to the size of the body, 
 about the same in all vertebrates. 
 Above the medulla can be seen only 
 the cerebellum and the cerebrum. 
 The parts corresponding to the optic 
 lobes and other minor centers of the 
 upper brain are wholly covered by 
 the enormous cerebrum. The sig- 
 nificance of this development of the 
 cerebrum and cerebellum has been 
 indicated in the foregoing chapter. 
 General plan of the minute nerv- 
 ous structure as related to conscious- 
 ness. The inner structure of this 
 nervous system is of importance to 
 the student of conscious processes. 
 It is, to be sure, impossible to trace 
 with the microscope the inner struc- 
 tures which are set in action when 
 any given mental process takes place. 
 For example, when one sees the letters of a printed page, there 
 
 38 X 
 
 Fig. 9. General form and 
 
 position of central nervous 
 
 orgrans 
 
THE HUMAN NERVOUS SYSTEM 
 
 39 
 
 IK 
 
 D- 
 
 ypfti 
 
 n 
 
 £ 
 
 'Ti^. 
 
 must be parts of the nervous system which are aroused, but we 
 
 cannot trace the exact paths along which travels the nervous 
 
 energy. We can trace the general plan of inner organization. 
 
 We can see the broad avenues, but 
 
 must infer most of the details. The 
 
 problem, presented to the student of 
 
 psychology is not unlike the problem 
 
 of planning a journey with a map. 
 
 One sees where there is a passage and 
 
 where one cannot go. Sometimes the 
 
 map is not complete. But in many 
 
 cases the m.ap gives a general view 
 
 of the journey and some idea of its 
 
 probable details. 
 
 The nerve cell and its parts. The 
 study of inner organization must begin 
 with a description of the elements out 
 of which the nervous system is made. 
 The elements are cells of a highly 
 specialized structure. These cells are 
 called neurones. Each one is made 
 up of a nucleus, a cell body of proto- 
 plasmic tissue surrounding the nucleus, 
 and a series of processes extending 
 from the cell body. The processes 
 are of two kinds ; namely, dendrites, 
 or branching arms, which usually con- 
 duct impulses toward the cell body, 
 and a single long nerve fiber which 
 carries the impulse outward from the 
 cell body. Fig. lo shows two neurones with all their charac- 
 teristic parts. It will be noted that the long fiber is made up 
 of several parts. There is a sheath around most of the long 
 fibers of the nervous system. This is not an essential part 
 of the nervous structure, but an external protecting structure. 
 
 Fig. 10. Two nerve cells 
 
 Two nerv^e cells, A and B^ 
 are here represented with 
 their axones C and D. C ex- 
 tends from the cell to a mus- 
 cle ; shortly after leaving the 
 cell the axone is surrounded 
 by a heavy protecting sheath, 
 as indicated in the figure, 
 and known as the medullary 
 sheath. At XX there ap- 
 pears an outer sheath, known 
 as the Sheath of Schwann. 
 The medullary sheath ends 
 at the point where the fiber 
 divides into a fine network 
 and passes into the muscle. 
 The axone D communicates 
 with another cell. (After 
 Testute) 
 
40 
 
 PSYCHOLOGY 
 
 The neurones are organized into chains. An impulse 
 acting on one cell is transmitted to other connected neurones 
 
 until, finally, the impulse 
 reaches a cell connected 
 with a muscle fiber. The 
 contact between neurones 
 in the higher nervous sys- 
 tems is indirect, as shown 
 in Fig. 1 1 ; that is, the fiber 
 from one cell does not pass 
 directly into another cell, but 
 breaks up into a fine net- 
 work of fibrils and inter- 
 laces with the dendrites from 
 other cells. The connections 
 of a single cell may be very 
 numerous by virtue of the 
 branching of the dendrites 
 and because of the indirect 
 relations between neurones. 
 
 Fig. II. A number of different types The point of relation be- 
 
 of connection between nerve fibers 
 and cells 
 
 A and A^ represent incoming sensory 
 fibers which bring stimulations from 
 different directions to the cell B. All of 
 the stimulations acting upon B are trans- 
 mitted along the fiber C, and at the end 
 of this fiber may affect various cells, such 
 as D and E. From the cells D and E 
 the stimulations may pass in different 
 directions, as indicated by the arrows. 
 The stimulations from A and A^ fuse in 
 the cell B. The stimulation from the cell 
 B is subdivided and redistributed from 
 D and E. All connections are indirect 
 or synaptic 
 
 tween two neurones is known 
 as a synapse. At the syn- 
 apses, impulses are redistrib- 
 uted in the greatest possible 
 variety of directions. 
 
 Complexity of structure 
 related to forms of action. 
 An examination of neurones 
 in various animals and at 
 different stages of individual 
 development shows clearly . 
 
 that the number of branches 
 of the cell is an important factor in determining the com- 
 plexity of the nervous organization into which the neurones 
 
THE HUMAN NERVOUS SYSTEM 
 
 41 
 
 may enter. Fig. 12 shows the increasing complexity of 
 neurones as we ascend the scale of animal life, and also 
 the increasing complexity of neurones of a single human 
 being as the nervous structures mature. The lesson to be 
 learned from these two series 
 of figures is clear. The com- 
 plexity of a cell and the number 
 of systems of connections into 
 which the cell may enter in- 
 crease in direct proportion to 
 each other. 
 
 Synapses as paths of organi- 
 zation. Whether they are units 
 in one of the lower centers 
 of the nervous system or 
 in a higher center, the cells 
 are always connected through 
 synapses and always transmit 
 impulses indirectly, thus com- 
 bining them and distributing 
 and redistributing them. The 
 nervous system has been com- 
 pared to a telephone switch- 
 board. The senses send in 
 excitations and the central 
 cells send these to the various 
 muscles of the body. On the 
 way to the muscles one set 
 of sensory excitations unites 
 
 with another set from some second organ of sense. The 
 combinations and distributions are somewhat like those of 
 the switchboard, only infinitely more complex. How com- 
 plex they are, one can imagine from the statement that 
 the total number of cells in the human nervous system 
 has been estimated as somewhat more than 12,000,000,000. 
 
 Fig. 12. The development in com- 
 plexity of nerve cells in the course 
 of animal evolution and in the 
 course of the development of a 
 single individual 
 
 A is the nerve cell of a frog ; B, a 
 lizard ; C, a rat ; Z>, man. The possi- 
 bility of developing definite paths 
 between various neurones increases 
 in proportion to the increase in the 
 number and complexity of the den- 
 drites from the cells, a is sl neuroblast 
 without dendrites, from the earlier 
 embryonic development of a human 
 brain> d shows the beginnings of den- 
 drites at the upper end of the cell. 
 In c, in d, and in e the dendrites 
 increase. The form of the mature cell 
 can be seen by referring to D in the 
 upper series. (After Cajal) 
 
42 
 
 PSYCHOLOGY 
 
 Paths in spinal cord. Let us follow a sensory impulse 
 through the lower paths of connection in the spinal cord. 
 Fig. 13 shows a magnified section across the cord. The 
 left side of the figure shows the appearance of the section 
 as seen under the microscope, while the right side is dia- 
 grammatic and allows one to trace some of the paths 
 through the tissue. The figure shovv^s that the cord is 
 bilateral ; that is, made up of two similar parts, one for 
 each side of the body. The nervous system throughout is 
 
 Fig. 13. Transverse section across the spinal cord 
 
 bilateral, just as are the nostrils and eyes and arms. In the 
 middle of the cord is a mass of cells. They have a gray 
 color and are called, collectively, gray matter. Around the 
 mass of cells are bundles of fibers which, because of their 
 glistening white color, are clearly distinguishable from the 
 cells. Some fibers are seen running into the cord and out 
 of it at the level of the section ; some are running back 
 and forth within the cord ; the majority appear as mere 
 spots because they run in a direction perpendicular to the 
 plane of this section and are cut squarely across in making 
 the section. 
 
THE HUMAN NERVOUS SYSTEM 43 
 
 On the right side of the figure at A is seen a nerve 
 trunk, or cable-Hke bundle made up of many nerve fibers. 
 This bundle of fibers breaks up into two roots ; the root P 
 is a sensory root along which sensory impulses enter the 
 cord ; the root M is a motor root along which impulses 
 leave the cord on their way to the muscles. At {7 is a 
 group of cells outside the cord, constituting an independent 
 ganglion. These are the cells which send their fibers to the 
 skin and receive the impression of touch. If one has the 
 patience to trace the fibers i, 2, 3, and 4, one will find 
 typical paths across the cord. This diagram alone is not 
 adequate, however, for many of the fibers must be shown in 
 a flat section of this kind as abruptly broken off. They 
 pass in reality out of the level of this section. Fig. 14 is 
 therefore added to give an idea of the way in which the 
 various levels of the cord are related to each other and 
 to the cerebrum. B represents a section of the spinal 
 cord \ A, ?i portion of the cerebral cortex. D^ represents 
 a region of the skin in which the sensory ending of a 
 tactual fiber from the cell D is distributed. A pressure 
 stimulation acting upon D^ will excite the nerve cell and 
 send a stimulation inward, as indicated by the arrows. 
 This stimulation will pass upward and downward to various 
 levels of the cord, as indicated by the branching of the 
 incoming fiber at e. Certain portions of this incoming stim- 
 ulation will be distributed through the spinal cord at differ- 
 ent levels, as indicated by the small collateral branches 
 passing horizontally out of the branches of the sensory 
 fiber (see also Fig. 13). At /" the incoming fiber communi- 
 cates with a nerve cell which, in turn, connects with the 
 cerebrum. This diagram is much too simple, more than 
 one cell being necessary for the transmission of this stimu- 
 lation to the higher centers. When the stimulus reaches g 
 in the cerebral cortex, it acts upon the large cell there shown, 
 and is transformed into a motor impulse. It then passes 
 
44 
 
 PSYCHOLOGY 
 
 downward along the fiber a^ which gives off horizontal 
 collaterals at different levels of the cord. Through one of 
 these collaterals or through the termination of the centrif- 
 ugal fiber, as indicated at ^, the stimulus is transmitted to 
 
 a motor cell in the 
 spinal cord, and 
 from this cell is 
 carried outward to 
 the muscles indi- 
 cated at C, 
 
 Reflex tracts. 
 When a sensory 
 stimulation passes 
 through the cord 
 and comes out in 
 an immediate reac- 
 tion, the pr(5cess 
 is called a reflex. 
 Thus, when one 
 touches a hot iron 
 and jerks back the 
 hand, such a proc- 
 ess is exhibited. 
 The nerve cells in 
 the cord are in this 
 
 Fig. 14. A diagram to illustrate the course of the fashion in control 
 
 sensory stimulation when it passes upward from c -pp^.^,, ^f j-Up 
 
 the level of the spinal cord at which it is received. •' 
 
 (After Cajal) sil^plest forms of 
 
 behavior, such as 
 the organic processes involved in digestion, and the simpler 
 protective movements, such as the withdrawing of the 
 hand above referred to. The nerve cells of the cord are 
 larger than in other parts of the system, hence do not 
 fatigue as readily; they watch over the body when the cells 
 in the higher centers are asleep. 
 
THE HUMAN NERVOUS SYSTEM 
 
 45 
 
 Transmission to higher centers. In addition to serving 
 as a seat for the reflex centers, the cord is a communicating 
 cable, as was shown in Fig. 14, carrying up to the brain 
 messages from the surface of the body and carrying back 
 messages to the muscles. 
 
 All nervous organs in part inde- 
 pendent centers. The higher nervous 
 centers above the cord are more 
 elaborate organs, but they are in 
 essential structure the same as the 
 cord. Below the cerebrum every 
 organ of the nervous system may be 
 said to consist, like the cord, of a 
 combination of relatively independent 
 cell centers and transmitting tracts. 
 In the cerebrum the whole surface 
 of the organ is made up of inde- 
 pendent cell centers. 
 
 Cerebellum. In the cerebellum the 
 central function predominates. This 
 
 . . cells c and to the larger 
 
 can be shown by exammmg a section cell b. From b, the stimu- 
 of this organ. Fig. 15 shows one of ^^^ ^^ ^^^^^^^ out^vard along 
 
 the descending fiber, d also 
 
 the lamellae, or folds of the cere- shows the termination of an 
 
 bellum, much enlarged. It will be incoming fiber. The organs 
 
 here figured serve to redis- 
 
 seen from this section that the cells tribute impulses from other 
 lie, not in the center of the orp:an as p^^^ ^^ ^^ nervous system. 
 
 . ' . , . . . ^ (After Cajal) 
 
 m the spmai cord, but at the outer 
 
 surface. Fibers enter the cerebellum in bundles and termi- 
 nate in a fine network of fibrils about the cells which are 
 situated on the surface. The surface, which is technically 
 known as the cortex, is increased very greatly in extent by 
 the folding, which can be seen in any figure representing 
 this organ. The result of the folding is that provision is 
 made for an enormous number of cells in a relatively 
 small cubical space. Through the action of the cells in 
 
 Fig. 15. A diagrammatic 
 
 section through a part of 
 
 one of the folds in the 
 
 cerebellum 
 
 A fiber, a^ entering from 
 some other part of the cen- 
 tral nervous system, distrib- 
 utes its impulse to the small 
 
46 
 
 PSYCHOLOGY 
 
 the cerebellar cortex, an impulse which comes into thi 
 cerebellum as a single impulse from one of the higher 
 centers, as, for example, from the cerebrum, may be sub- 
 divided into a great number of currents so as to arouse, 
 
 Corpus Callosum 
 
 Cerebrum 
 
 Peduncular 
 Fibers 
 
 Cerebrum 
 
 Peduncular 
 Fibers 
 
 Cerebellum. 
 
 Fig. 1 6. The brain seen from below and cut open to show the paths of 
 fibers from the cortex of the cerebrum to the lower organs 
 
 In the lower part of the figure near the middle is the medulla. One side of the 
 cerebellum is shown on the left. Sections of the cerebral cortex constitute the chief 
 part of the figure, especially at the left above and below. From the cortex peduncular 
 fibers pass downward. Near the top of the figure the heavy band of fibers constituting 
 the corpus callosum crosses from one hemisphere to the other. (After Edinger) 
 
 when distributed to the active organs, a whole system of 
 muscles. Indeed, there is evidence that the cells of the 
 cerebellum contribute in the way indicated to muscular 
 coordinations in all parts of the body. 
 
THE HUMAN NERVOUS SYSTEM 
 
 47 
 
 Cerebrum and its systems of fibers. From the cord and 
 cerebellum and the other minor centers of the nervous sys- 
 tem we turn to the cerebrum. Our study of the evolution 
 of the nervous system showed the dominating importance 
 of this organ in all of the higher animals. The cerebrum 
 is a complex organ to which sensory impulses come from 
 all parts of the body and from which motor impulses are 
 sent out to all the voluntary muscles. It is not directly 
 
 Fig. 17. Sketch showing some of the association fibers connecting various 
 parts of the cortex of the cerebrum with one another. (iVfter Edinger) 
 
 connected with the surface of the body, but is indirectly 
 the organ in control of all parts of the body. It is a cen- 
 tral clearing house for the organism. It is the part of the 
 body most intimately related to consciousness. 
 
 In structure the cerebrum consists of an external folded 
 or convoluted layer of cells known as the cortex. This cor- 
 tex is from one eighth to one twelfth of an inch in thick- 
 ness and shows many variations in structure in its different 
 parts. To these variations in the structure of the cortex 
 
48 
 
 PSYCHOLOGY 
 
 further reference will be made later. The central mass of 
 the cerebrum is composed of fibers which provide for the 
 connection of each point of the cerebral cortex with every 
 other part of the nervous system. The general structure of 
 the cerebrum may, perhaps, be comprehended most easily 
 by referring to the systems of cerebral fibers. There are 
 
 three types or systems of 
 fibers. 
 
 First, there are great 
 bundles of fibers connect- 
 ing the cerebrum with the 
 lower centers and constitut- 
 ing the paths along which 
 motor impulses descend. 
 These constitute the pe- 
 duncular tract. Some of 
 these fibers were shown 
 in the diagram illustrating 
 
 Fig. i8. A transverse section across the the paths in the spinal 
 tv70 hemispheres in a plane passing verti- cord (Fig. I4) ; the whole 
 cally throusfh the cheek bones parallel , . i • t— /- 
 
 i r ^- ^u 4. system is shown m l^is^. 16. 
 
 to a line connecting the two ears -^ ^ 
 
 • . . , , ^, , . , , ,. , Second, there are fibers, as 
 
 This section shows the fibers which estabhsh \ ^ \ 
 
 communication between the two hemispheres. Shown In -Tig. I /^ whlch 
 When the fibers in this figure are supple- ^onnect the different poiutS 
 
 of the cortex of one hemi- 
 sphere with other points 
 in the same hemisphere. 
 These fibers are techni- 
 cally known as association fibers. The third bundle of fibers 
 extends from one hemisphere of the cerebrum to the other 
 hemisphere. The fibers of this group are known as the 
 commissural fibers, and go to make up the corpus callosum, 
 or bridge of fibers, conspicuous in any median section of 
 the cerebrum and shown in Fig. 18. This bridge was also 
 shown in Fig. 16. ' . 
 
 mented by those represented in the two 
 preceding figures, it will be seen that every 
 point on the cortex of the cerebrum is in 
 communication with all other parts of the 
 nervous system. (After Edinger) 
 
THE HUMAN NERVOUS SYSTEM 
 
 49 
 
 Structure of cerebrum as indicating way in which impulses 
 are organized. No clearer evidence of the function of the 
 cerebrum can be found than that which is given in the 
 structure of its systems of fibers. An impulse which reaches 
 the cells of the cerebral cortex through the sensory, or 
 incoming, fibers of the peduncular tract is brought to the 
 cortex for the purposes of redistribution and combination 
 with other impulses. The elaborate system of interconnect- 
 ing tracts provides for infinite recombinations of nervous 
 
 Fig. 19. Two sections representing portions of the cerebral cortex from 
 
 two areas of the human brain 
 
 On the left there are shown the sixth and seventh layers of the visual center. The 
 horizontal distribution of the dendrites of the large pyramidal cells is characteristic 
 of this region. On the right is a part of the motor center, showing giant pyramidal 
 cells which in size and distribution of dendrites differ from those in other centers. 
 
 (After Cajal) 
 
 impulses. We shall refer in all of our later discussions to 
 the organization of nervous processes which goes on in the 
 cerebrum. The term ''organization," so used, refers to the 
 fact that a nervous impulse, when it reaches the cerebrum, 
 is united with other impulses and is carried along complex 
 series of paths, until finally it is discharged into the motor 
 channels which pass outward to the muscles. No impulse 
 which reaches the cerebrum can escape combination with 
 other impulses ; the purpose of the whole structure is to 
 provide channels for the most complete interrelating of all 
 the higher nervous processes. 
 
50 
 
 PSYCHOLOGY 
 
 ^ 
 
 Cerebral cortex complex. The cortex of the cerebrum 
 has a structure of such complexity that it h^s been impos- 
 sible, until very recently, to define with 
 anything like certainty its various parts. 
 Fig. 19 represents two typically different 
 areas. An examination of these dia- 
 grams shows that the cells are of differ- 
 ent types and the mode of interlacing 
 of their dendrites is different. Fig. 20 
 shows a diagrammatic representation of 
 some of the different elements which 
 are characteristic of the cerebrum. By 
 means of this figure the cells and fibers 
 which in reality are interlaced can be 
 distinguished from each other. 
 
 Localization of functions. Though we 
 are ignorant of the meaning of many of 
 the details of cortical structure, we are 
 well informed as to the functions of 
 many areas of the cortex. The cortex 
 may be divided into three kinds of areas 
 or centers ; these are sensory areas, 
 motor areas, and association areas. The 
 sensory areas are those which have the 
 most direct relations to the various 
 organs of sense ; the motor areas are 
 those which stand in most direct rela- 
 
 does not represent ade- ^ions to the active orgaus. There is no 
 quateiy the complexity of part of tlic ccrcbrum which has simple 
 
 the structure. Many small i • i* . i .- ^ ^i r 
 
 cells are not here repre- ^^d immediate relations to the surface 
 
 sented. A general impres- of the body, SO tHat the tCrmS "~ SCUSOry" 
 
 gain;d^f"he fig^'^re o'f ^^^ '' motor '' are merely relative terms, 
 
 the complexity of the cor- the scusory ccutcrs being those points 
 
 tex. ( ter E mger) ^^ which the Stimulations from the organs 
 
 of sense are first received in the cerebrum, the motor areas 
 
 Fig. 20. ■ A diagram- 
 matic section showing 
 the structure of the 
 cortex of the cerebrum 
 
 On the left-hand side of 
 the figure the cells alone 
 are shown. On the right- 
 hand side of the figure 
 the fiber systems alone 
 are indicated. The figure 
 
THE HUMAN NERVOUS SYSTEM 51 
 
 being those points from which the stimulations pass out of 
 the cerebrum on their way to the muscles. The association 
 areas, as the name indicates, are areas of a still more indi- 
 rect character, in which sensory impulses, after being received 
 in the sensory areas, are recombined and redistributed. In a 
 very proper sense of the term, all cerebral areas are associ- 
 ative areas, for they all serve the function of indirect com- 
 bination and distribution of nervous impulses. Those which 
 are specifically designated as associative have claim to the 
 specific name because they perform a function of even higher 
 combination than do the others. Figs. 21 and 22 show the 
 centers of these types which appear on the surfaces of the 
 human cerebrum. 
 
 Stimulation the first method of discovering cerebral locali- 
 zation. It may be interesting to digress for a moment from 
 the structure of the cortical centers for a discussion of the 
 methods by which these centers have been located. A great 
 number of experimxCnts have been tried on the higher 
 animals. Certain of the areas have been artificially stimulated, 
 and when muscles in different parts of the body have 
 responded promptly and regularly to these stimulations, the 
 connection betw-een the areas stimulated- and the muscles 
 thrown into action has been recorded. Evidently, artificial 
 stimulations of this kind w^ould be of little value in locating 
 sensory or association areas, for there are no clearly marked 
 muscular effects when the stimulus is applied to areas other 
 than those directly related to the muscles. For example, 
 the stimulation of the visual center would show only the 
 motor effects of such stimulation and would not give any 
 clear indication of the sensory character of the area. 
 
 Extirpation and comparison of pathological cases. A sec- 
 ond type of experiment which has been productive of results 
 depends upon extirpation of the tissues. Certain areas of the 
 cerebral cortex of animals are cut or burned out, and the loss 
 in function resulting from this removal of the nervous tissue 
 
52 
 
 PSYCHOLOGY 
 
 is carefully studied. This method can be used in locating 
 both sensory and motor centers. There are cases of disease 
 of the human nervous system analogous to these cases of 
 
 Fig. 21. The outline of the lateral surface of the cerebrum with the typical 
 
 convolutions, as given by Flechsig 
 
 The shaded portions indicating the sensory and motor centers, and the small circles 
 indicating certain well-defined association areas, are given according to Tschermak 
 in Nagel's " Handbuch der Physiologic des Menchen." Vertical lines in the shaded 
 areas indicate motor areas ; horizontal lines indicate sensory areas ; oblique lines 
 indicate sensory-motor areas. /, 7, /, 7, i are the motor areas for the toes and 
 foot; 2, 2, 2 are the motor areas for the shoulder, elbow, and wrist ; j, j, j, j are 
 the areas for the fingers and thumbs ; ^, 4^ 4, 4 are the motor areas for the eye 
 and other parts of the face ; j is the center for the vocal cords ; 6, for the tongue ; 
 7 is the sensory area for the head; 5, 8^ 5, 8 are the sensory areas for the regions 
 to which motor stimulations are distributed by the areas 1-6 ; 9, g are the sensory- 
 motor areas of the trunk ; 77, visual area and occipital area for the eye movements ; 
 72, auditory area and temporal center for visual fixation ; 7j, olfactory bulb ; 14^ 
 probably olfactory area. The area where vertical and horizontal lines cross between 
 the motor areas 1-6 and the sensory areas 7, 8 is probably connected with the 
 muscle sense. A^ motor writing center; B, Broca's motor speech center; (T, prob- 
 ably memory-motor speech center ; Z), sensory music center ; E^ Wernicke's sensory 
 speech center ; F, memory-sensory speech center ; G\ mem.ory reading center ; H, 
 sensory reading center. All of these lettered areas are associational centers 
 
 extirpation in animals, and careful study of the loss of 
 human functions shows that the human cortex is subdivided 
 in much the same way as that of the higher mammals. 
 
THE HUMAN NERVOUS SYSTEM 
 
 53 
 
 Embryological methods. There are other methods of 
 investigating cerebral areas which deal with the internal 
 structures. One of the most productive of these methods 
 depends upon the fact that the different areas of the cere- 
 brum do not develop at exactly the same period in the 
 embryological or infant life of a human being. The human 
 
 Fig. 22. The median surface of the human cerebrum showing, as in Fig. 21, 
 
 the various areas 
 
 8, sensory area for the lower extremities; g, g, sensory-motor areas for the trunk; 
 10, motor area of the lower extremities ; 11, visual area and occipital motor area for 
 visual fixation ; ij, olfactory bulb ; 14, probably olfactory area ; ij, ij, is, ij, olfactory 
 areas ; 16, 16, probably gustatory areas. (For reference to authorities for this figure, 
 
 see Fig. 21) 
 
 embryo exhibits in its early stages a development of the 
 nervous system about the central fold or fissure, known as 
 the fissure of Rolando. This area of earliest development 
 is in the region marked in Fig. 21 as the motor area and 
 the area of tactual sensitivity. Later, the nervous system 
 matures in the remaining sensory centers in such sequence 
 that it is possible, by the study of the microscopic anatomy, 
 to secure a fairly complete chronological account of the 
 
54 PSYCHOLOGY 
 
 development of the different regions. The association areas 
 are the latest to develop. Indeed, in the association areas 
 the development can be traced for a period after birth, and 
 indirect evidence seems to make it clear that the development 
 goes forward well on into mature life. 
 
 Association areas. The visual area in the occipital region, 
 as indicated in Figs. 21 and 22, is the area through which 
 impulses resulting from retinal stimulation are first intro- 
 duced into the cerebrum. A similar area for the reception 
 of auditory impulses appears, as indicated in Fig. 21, just 
 below the Sylvian fissure. Without entering further into a 
 discussion of the various centers, it will be enough to call 
 attention to the relation between the visual and auditory 
 areas and the association area lying between them. The 
 association area in question, known as the parietal associa- 
 tion area, has developed in the course of the evolution of 
 the cerebrum between the visual and the auditory centers as 
 the area in which the stimulations from these two centers 
 may be brought together and combined. There are many 
 evidences that the combinations of visual and auditory im- 
 pulses do, as a matter of fact, go on in the parietal associa- 
 tion center. For example, there is in this parietal region 
 one area which is of great importance in the function of 
 speech. If this association area involved in speech is dis- 
 turbed, the individual may remain quite capable of receiving 
 visual impressions through his eyes and of receiving audi- 
 tory impressions through his ears. He may even be capable 
 of articulation, which is a motor function, but he will lack 
 the ability to interpret the impressions which he receives 
 when he hears or sees words or to give expression to a 
 coherent series of ideas. The area in question has there- 
 fore been designated as the ideational area. It is ideational 
 rather than sensory, because it is the seat of a series of 
 functions more elaborate than those which are involved in 
 the mere reception of impressions. It is the center for the 
 
THE HUMAN NERVOUS SYSTEM 55 
 
 combination of visual or auditory impressions. More than 
 this, the association area is a center which becomes more 
 and more highly organized in its inner structures through 
 use, so that its influence on any present impulses is, doubt- 
 less, such that we are justified in saying that it adds to 
 these impulses the effects of past experience. In an im- 
 portant sense it associates present impressions wdth past 
 impressions, as well as combines present impressions from 
 different senses. It thus serves in a large way the function 
 of a reorganizing center for visual and auditory impressions. 
 Significance of the central position of the general motor 
 area. Another important fact, which wdll be observed im- 
 mediately on the inspection of Figs. 21 and 22, is that the 
 general motor area occupies a relatively central position in 
 the cerebrum. Around the motor area are a group of asso- 
 ciation areas where impulses are united on their way to 
 motor discharge. The area of touch and of general sensi- 
 bility seems to offer an exception to the general rule of 
 distribution of sensoryand association centers around the 
 motor area. This sensory area is not separated from the 
 motor area by an association area, as are the other sensory 
 centers. We see in this relation of the cerebral centers for 
 touch and movement the structural fact which corresponds 
 to the functional fact that the skin and other tissues which 
 give rise to tactual sensations would naturally, as the earliest 
 organs, stand in so intimate a relation to the muscles that 
 the later and more highly developed organs of sense could 
 not be expected to duplicate this relation. As the primitive 
 tactual sensory surfaces came to be supplemented by new^er 
 and more highly specialized organs of sense, the nervous 
 centers for the newer senses were forced to take up more 
 remote and complex relations to the motor area, while the 
 original senses did not lose the intimate relation which 
 they bore from the first. The development of the higher 
 senses furnished also opportunity for greater variety in the 
 
56 PSYCHOLOGY 
 
 combination of sensory impulses ; consequently the associative 
 functions and the areas corresponding to them increased 
 with the development of variety in the sensory functions. 
 The association centers, which are the structural areas given 
 up to the function of working over sensory impulses, natu- 
 rally developed between the centers which performed func- 
 tions of reception, or the sensory functions, and those which 
 performed the functions of motor discharge. The topogra- 
 phy of the cerebral centers thus reflects directly the gradual 
 evolution of more and more elaborate system_s of nervous 
 organizations. 
 
 Speech centers. Another group of facts which will serve 
 to make clear the character of the association areas is to be 
 found by examining that portion of the cerebrum which is 
 known as the speech area. This region of the brain was 
 first recognized by the anthropologist Broca as intimately 
 related to the functions of speech. He found that disease 
 in this area resulted in impairment of the patient's ability 
 to use or understand language. Later studies of aphasia, as 
 the pathological loss of speech is called, have increased our 
 knowledge of this area, especially since it has become pos- 
 sible through the examination of a large number of cases 
 to distinguish a variety of forms of partial aphasia. Thus, 
 a person may be able to understand words which he hears, 
 but be quite unable to understand words which he sees on 
 a printed page. This form of so-called visual aphasia is 
 paralleled by forms of auditory aphasia, in which the subject 
 is able to read, but cannot understand words which he hears 
 spoken. These two forms of partial aphasia indicate that 
 the connection between the speech center and either the 
 auditory or visual center may be interrupted without destroy- 
 ing the connection between the speech center and the other 
 sensory area. If the disease of the speech center is strictly 
 localized so as to interrupt only its connection with the 
 visual center, the other functions may remain intact, while 
 
THE HUMAN NERVOUS SYSTEM 57 
 
 the visual forms of recognition of language are interrupted. 
 Conversely, if the connections with the auditory centers 
 alone 'are interrupted, visual recognition may continue. 
 
 Turning now to the various forms of motor aphasia, or 
 forms affecting the power of expression as distinguished 
 from the forms of sensory aphasia mentioned, we find that 
 an individual may lose the power of articulation without los- 
 ing the ability to write, or he may lose the ability to write 
 without losing the ability to articulate. In either one of 
 these forms of motor aphasia, the subject may be compara- 
 tively free from sensory deficiencies. The lack of ability to 
 articulate, when all of the other phases of the function of 
 speech are present, show^s that the connection with the visual 
 and auditory centers may be complete, as well as the con- 
 nection with the motor area for the hand movement involved 
 in writing, while the motor connection with the center which 
 sends impulses to the muscles of the vocal cords may be 
 tem.porarily or permanently interrupted. 
 
 Broca's convolution an association center. Broca's con- 
 volution thus turns out to be an association area in w^hich 
 a great variety of lines of connection converge. It is not a 
 part of the nervous system which acts independently in the 
 control of a separate faculty of speech ; it gains its signifi- 
 cance in the individual's life as a center for the organization 
 of stimulations received in other parts of the cortex and 
 transmitted through the cells and fibers of this area on the 
 way to the motor area. 
 
 Phrenology not in accord with clearly known facts. It 
 may be well to call attention at this point to the fundamental 
 distinction between the teachings of phrenology and the dis- 
 coveries of modern brain physiology. Phrenology maintained 
 that different parts of the brain are given over to different 
 faculties. For example, phrenology believed in a certain area 
 for the recognition of form, another area for the recognition 
 of number, an area for the function of parental love, and one 
 
58 PSYCHOLOGY 
 
 for the general trait of combativeness. There is no justifica- 
 tion for a theory of locaHzation based upon a subdivision of 
 consciousness into such mythological faculties. The cortex 
 can be subdivided into areas concerned first with sensory 
 impulses, second with motor impulses, and third with organi- 
 zation. Conscious processes must be considered as having 
 their physiological conditions, not in separate points assigned 
 to imaginary faculties, but rather in the organized activity 
 of sensory, motor, and association areas. For example, the 
 recognition of form naturally includes certain sensory func- 
 tions and certain associative processes. The general neural 
 basis for such sensory and associative processes we know, 
 as has been shown in the foregoing paragraphs. To be sure, 
 we do not know at the present time all the details of the 
 cerebral map, but the broader outlines are too'clearly defined 
 to leave any room for mistaken notions with regard to the 
 kind of functions which are provided for in the different 
 areas of the cerebrum. 
 
 Frontal association area. One area of the cerebrum which 
 has been the subject of much speculative discussion is the 
 frontal area, or that portion of the cerebrum which lies in 
 front of the motor area. In certain cases large portions of 
 this area have been destroyed without apparent interference 
 with the individual's normal functions. There is a famous 
 case known as the American Crowbar Case, in which a 
 common laborer, through an accident in blasting, had a very 
 large portion of this frontal lobe removed by a crowbar pass- 
 ing through the roof of his mouth and out through the top 
 of his skull. The individual in question continued to live 
 with no serious interruption of his regular nervous or phys- 
 ical functions. Such cases as this may possibly indicate 
 that the association areas are not fully developed in some 
 individuals. In general, it is doubtless true that association 
 areas, more than other parts of the nervous system, are left 
 open for development through individual experience. If this 
 
THE HUMAN NERVOUS SYSTEM 59 
 
 conception is accepted, it is not surprising that an individual 
 might be deprived, as in the case cited, of the possibihty of 
 further development, or even of some of his higher forms 
 of association without the loss being obvious to himself or 
 to those who observe him. Recent experiments, which have 
 been tried in the extirpation of the small frontal area in cats 
 and monkeys, show clearly that the frontal area is the part 
 of the nervous system involved in newly acquired habits. 
 The fact that man, who alone of all the animals has a large 
 frontal lobe, is the learning animal par excellence further 
 confirms the general view derived from these experiments. 
 
 General principles of nervous action. It remains to call 
 attention to a few of the general facts which are known 
 with regard to action within the nervous organs. 
 
 Active organs as termini of all nervous impulses. Nerve 
 impulses under normal conditions always travel forward in 
 the single direction from the sensory centers toward the 
 motor centers. There is no reversing of a nervous current. 
 If it were otherwise, a central nervous process might travel 
 down a sensory fiber and arouse the sense organ. We 
 should see colors and hear sounds whenever the central 
 system was excited. Under normal conditions this does not 
 happen. The sensory impulses come only from the sense 
 organs and always move, even though the path be complex, 
 in the direction of the motor centers. 
 
 Principle of facilitation. When currents pass through 
 the nervous tissue they leave behind paths or tracts which 
 facilitate the later transmission of like impulses over like 
 paths. Indeed, it seems that in many cases this facilita- 
 tion of transmission goes far enough to reduce the length 
 of the path. Where the first transmission was over a long 
 complex path, later transmissions reach the same end by 
 a more direct route. 
 
 Principle of association of centers of high tension. When 
 two centers in the cerebrum are in simultaneous action, 
 
1/ 
 
 1/ 
 
 6o PSYCHOLOGY 
 
 there is a tendency for a path or connection to be set up 
 between the two. The active centers may be thought of as 
 points of high tension and the currents which they send out 
 tend to flow together. 
 
 Diffusion as opposed to organization. Impulses can travel 
 through the tissue not merely along the paths which are 
 defined by the branches of the cells but also fromi cell body 
 to cell body. This is especially true in the early stages of 
 the life of an individual when tracts are not fully devel- 
 oped, and it is true at all stages of individual development 
 for very strong stimulations. The result of such indefinite 
 transmission is a diffuse condition of excitement. Such dif- 
 fusion is often the first. stage of organization. After a period 
 of diffusion, paths are worked out to carry by definite chan- 
 nels impulses which at first were spread vaguely through the 
 nervous tissue. 
 
 Principle of progressive organization. Under the forego- 
 ing principles the nervous system is continually becoming 
 more and more highly organized. The effect of experience 
 is to be found not merely in the fact that certain paths are 
 recorded in the nerve cells, but also in the fact that in their 
 totality these parts develop into increasingly complex series 
 of interconnections. This is the essential fact which must 
 be kept in mind if we would understand the progress of the 
 individual from infancy to mature mental life. Each day's 
 experience builds up new systems of tracts in the nervous 
 tissues and thus leads to higher and higher levels of behavior 
 and experience. 
 
 If we keep this formula in mind, we shall be able to 
 understand the higher levels of consciousness. Such higher 
 levels are always due to the interrelating of lower forms of 
 experience. Ideas are made up of related present impres- 
 sions and the results of past impressions. Thoughts are 
 made up of interrelated ideas. The formula in every case 
 is one of more and more complex interrelations. 
 
CHAPTER IV 
 
 CLASSIFICATION OF CONSCIOUS PROCESSES 
 
 Classification derived from study of nervous organs. The 
 
 study of consciousness has often been taken up without the 
 preHminary discussion of the nervous system through which 
 the foregoing chapters have carried us. It would be entirely 
 legitimate, as remarked in an earlier chapter, to begin the 
 study of mental processes by looking inward on one's own 
 experiences and describing the various facts which intro- 
 spection there discovers. The array of facts which would 
 thus come to light would, however, be confusing in their 
 variety and complexity. It is much simpler to approach the 
 facts of mental life with the type of classification suggested 
 by the knowledge that sensory processes enter the central 
 organs and are there redistributed and organized on the way 
 to the motor organs. With this classification to guide us, ' 
 the facts of experience fall into order and lend themselves 
 to orderly scientific treatment. 
 
 Classification from observation superficial. An analogy 
 will help to make clear the difficulty of classifying facts on 
 the basis of unguided observations. If an ordinary man were 
 asked to classify the organs of the body, he would begin by 
 pointing out the arms and legs as important subdivisions. 
 Then he would point out the trunk and head, and so on. 
 The student of physiology realizes that these gross external 
 subdivisions are, indeed, important, but they furnish for 
 science an inadequate basis of study as contrasted with such 
 fundamental distinctions as those between muscles and bones, 
 between organs of respiration and organs of circulation, and 
 
 6i 
 
62 PSYCHOLOGY 
 
 so on. The moment we divide up the body on these last- 
 mentioned Hnes of functional differentiation we find that 
 our science is following productive trains of description 
 and explanation. 
 
 In much the same way popular distinctions of the dif- 
 ferent phases of experience must be revised before they can 
 be used by science. A striking illustration of this is to be 
 seen in the fact that in popular thought pleasure and pain 
 are usually treated as facts of the same order, though con- 
 trasted in quality. A moment's consideration will make it 
 clear that pain ordinarily arises from some definite point in 
 the bodyc It is a type of experience which we classify in 
 science along with those experiences which come from the 
 stimulations of the skin or the inner surfaces of the body 
 and are technicallv known as sensations. Pleasure, on the 
 other hand, has a totally different kind of origin. It is not 
 a phase of sensation ; it does not come from particular points 
 of stimulation. It must be treated as a type of experience 
 which grows out of general organic excitations of a much 
 more central character than those which are involved in the 
 production of pain. Again, such a term as '' attention,'' which 
 has a large practical use in ordinary life, is one of the most 
 confusing terms when it is carried over into scientific study. 
 If one recognizes, as he must in psychology, that attention 
 is capable of a great variety of different degrees, he will find 
 it possible to extend this term over every possible experience. 
 There are forms of intense and vivid consciousness for which 
 some term, such as ''vividness" or ''attention," is undoubtedly 
 required in science. There are other forms of consciousness 
 which are relatively vague and indistinct, yet when dealing 
 with these cases we cannot fail to recognize the necessity of 
 using the word " attention " or some such phrase as " low 
 degree of attention," if we have adopted the word into our 
 scientific vocabulary. These illustrations make clear the 
 problem which confronts psychology when the attempt is 
 
CLASSIFICATION OF CONSCIOUS PROCESSES 63 
 
 made to secure an analysis which is at once satisfactory 
 for purposes of scientific treatment and explanation and in 
 keeping with ordinary introspective observations. 
 
 Historical threefold classification. In the history of psy- 
 chology many efforts have been made to develop an appro- 
 priate scientific classification of mental processes. One of 
 the classifications which was for a long time generally ac- 
 cepted is that which grouped all forms of experience under 
 the three general heads of knowledge, feeling, and volition. 
 There can be no doubt that such a threefold classification 
 describes certain fundamental differences in conscious ex- 
 perience. The man who is engaged in thinking out some 
 problem of science is certainly not at that moment absorbed 
 in an intense feeling or emotion. On the other hand, the 
 man who is thoroughly angry over some situation which has 
 arisen is by no means in a condition to consider logically 
 and judiciously the facts which appeal to his thoughtful 
 neighbor who is free from emotional excitement. It is some- 
 what more difificult to Justify the classification of volition as 
 different from knowledge and feeling, for no serious thought 
 is possible without some voluntary effort, and no emotion 
 ever arises without inducing some form of action. Yet, 
 even though volition is intimately interwoven in all forms 
 of knowledge and feeling, there are certain cases of decision 
 which are not to be regarded as typical processes of know- 
 ing, or processes of feeling; hence the term ''volition" is 
 needed for a full description of mental activities. 
 
 Historical twofold classification. Another somewhat dif- 
 ferent type of classification has been used by certain writers ; 
 according to this, only two different types of experience 
 are distinguished ; namely, knowledge on the one hand, and 
 active processes on the other. This twofold classification 
 offers less difficulty to explanatory science than the three- 
 fold classification, because it is more general. In bringing 
 together a great variety of facts under the active processes 
 
64 PSYCHOLOGY 
 
 so called, we are freed from the necessity of making any 
 sharp distinction between the feelings, which are undoubtedly 
 active aspects of consciousness, and decisions, which from 
 any point of view must be regarded as active. 
 
 Without ignoring in our later discussions the historic dis- 
 tinctions between knowledge, feeling, and volition, it will be 
 possible to draw from our study of the nervous system a 
 more productive classification. 
 
 Classification according to nervous processes. The most 
 fundamental fact discovered with regard to nervous struc- 
 tures was that they couple the sense organs with the organs 
 of behavior. Consciousness arises during the translation of 
 a sensory impression into a motor response. Every conscious 
 process will, first of all, have certain aspects which are due 
 to the sensory impression and, second, certain other aspects 
 which are related to the motor response. 
 
 Third, every nervous process in its passage from the sense 
 organ to the point of discharge encounters certain other 
 nervous processes and is fused with them. Consciousness 
 is in an important sense the result of fusions of many 
 impressions. Whoever would understand the facts of experi- 
 ence must ask how they are built up out of the combination 
 of many elements. We must study, therefore, the fusions 
 which condition conscious phenomena. 
 
 Fourth, every sense impression on its way to the motor 
 discharge is modified in character by past processes in the 
 nervous system. The past is brought over into the present 
 by the structural changes which are recorded in the nervous 
 system and influence every new impression in its passage 
 through this system. 
 
 Fifth, the most impressive lesson which was drawn from 
 the study of the evolution of animal forms was that in the 
 highest nervous systems great areas are set aside for a type 
 of indirect recombinations which are of such importance 
 that they must be distinguished from the fusions referred to 
 
CLASSIFICATION OF CONSCIOUS PROCESSES 65 
 
 under third, above. The recombinations due to the action 
 of the association areas are of a higher order and are to be 
 distinguished as indirect or abstract processes. 
 ^ Example of Scientific analysis and classification. The 
 classification of facts here outHned will, perhaps, be better 
 understood if an example is used. Let one look at a printed 
 word. The experience which results may seem to the un- 
 thinking observer to be a single simple process of recog- 
 nition. A mioment's consideration will bring out endless 
 complexities. In the first place, the experience breaks up 
 into impression and interpretation. There is a part of the 
 word-consciousness which comes from the page, a part which 
 comes from past experience. The part of the experience 
 which comes from the page proves on closer examination 
 to be complex. There are black and white impressions in 
 sharp contrast with each other which fuse into the complex 
 image of letters and unite into a single image of a word. 
 There are motor tendencies which often are vivid, — one 
 tends to say the word, or there is an incipient impulse to 
 obey its dictates as one realizes in one's own experience 
 when the word ''down" is contrasted with the word ''up." 
 Finally, the meaning calls up elaborate thought-processes 
 which carry one far beyond the present word and arouse 
 associations of indefinite complexity. 
 
 This example serves to show how even superficial study 
 of a single experience demonstrates the necessity of some 
 plan of classification under which the various aspects of a 
 mental process may be described and explained. Further- 
 more, the example is a fortunate one with which to demon- 
 strate the importance of those indirect elements of experience 
 not derived from sensation. The impression is the least 
 important part of the word-consciousness. Our scheme of 
 classification is important not merely as a means of securing 
 a complete description but also as clue to the scientific ex- 
 planation of mental processes. The student of psychology 
 
66 PSYCHOLOGY 
 
 must constantly keep in mind the necessity of standing 
 outside himself and getting a true perspective of his mental 
 processes. One is likely to overemphasize the impression 
 which comes from without and to overlook one's own con- 
 tribution ; it is accordingly the business of scientific psy- 
 chology to restore the balance and give a true emphasis to 
 that which comes out of past experience and that which is 
 due to the central and motor processes which attach to the 
 impression. 
 
 Relation of classification to introspection. The classifica- 
 tion of psychological problems is therefore frankly borrowed 
 from the clue furnished by the study of the nervous system 
 rather than left to the accidents of introspection. Intro- 
 spection will not be ignored, but the facts derived by looking 
 into experience will be ordered according to the formula 
 derived from objective studies. Perhaps a more fortunate 
 method of expression will be to say that the classification 
 having been determined through a study of nervous struc- 
 tures, introspection will be used to reveal the classes of facts 
 which the study of the nervous system teaches are important. 
 
 Sensations. First we shall seek facts of sensation. Im- 
 pressions come to us from the outer world through each 
 of the senses. Red, green, a shrill sound, a musical tone, 
 an odor, a taste, a pressure against the skin are typical 
 cases of this class. There is no difficulty in justifying an 
 examination of sensations. 
 
 Reactions and attitudes. Then there are reactions to 
 sensations. In some cases these reactions are very direct ; 
 this is true where the whole process is simple. Most ex- 
 periences have grown very complex and the reaction to the 
 impression comes only after an interval during which the 
 sensation has been coupled with many other factors of 
 experience. It is sometimes extraordinarily difficult to de- 
 termine how reactions are related to impressions. The 
 psychologist finds it better in such cases to postpone the 
 
CLASSIFICATION OF CONSCIOUS PROCESSES 6j 
 
 full discussion of reaction until after he studies the complex 
 of facts added to sensory impressions. A complete post- 
 ponement of the study of reactions would, however, m.ake 
 difficult the explanation of those simple processes in which 
 the reaction follows directly on the impression. The reac- 
 tions will therefore be taken up first in an introductory 
 way in chapters immediately following the treatment of 
 sensations, and later the topic will be amplified by a study of 
 the more remote and complex forms of organized reaction. 
 
 The conscious fact which parallels a reaction deserves 
 a name. The word '' attitude " serves very well this pur- 
 pose. We say in common parlance that we feel an attitude 
 of interest or disgust. Our study will show us that all atti- 
 tudes of mind are aspects of consciousness related to reac- 
 tions. We have attitudes of belief and incredulity, attitudes 
 of sympathy and aloofness. All these are as distinct from 
 sensations as facts of consciousness can be from each 
 other. We shall attempt a classification of some of the 
 more fundamental attitudes. 
 
 Fusion and perception. The term '' fusion " suggests cer- 
 tain simple combinations of sensory facts such as the recog- 
 nition of an orange as the source of a certain color, a 
 certain odor, a taste, and a sensation of roughness to the 
 touch. In experience all these qualities fuse. They are 
 located together in front of us or at the side. They make 
 up our experience of an object. We speak of the expe- 
 rience as a sense percept. 
 
 Memory. The term ''memory" includes a great many 
 factors of which we make use, but which we seldom unravel 
 from the complex of present experience. One meets a 
 friend, and past experience, unnoticed as a separate aspect 
 of mental life, determines one's whole recognition. One 
 reads into the present all the pleasant associations of earlier 
 days. On other occasions one labors to call up some for- 
 gotten or half-forgotten fact. The effort to recall makes 
 
68 PSYCHOLOGY 
 
 one actually aware of the distinction between the present and 
 the past. Here is an opportunity in treating of memory to 
 draw productive distinctions between many different kinds 
 of memory. 
 
 The process of ideation. There are ideas and combina- 
 tions of ideas which constitute the highest forms of men- 
 tal activity. The idea which one has when he thinks of 
 honesty is something more than sensation or attitude or 
 memory; it is the understanding of a whole series of rela- 
 tions. We speak of this as an abstract idea, meaning by 
 that term that we have cut loose from impressions and are 
 in a world of our own making. The processes of abstrac- 
 tion exhibit the creative power of a highly developed indi- 
 vidual as no other mental process can. The animals do not 
 have, so far as we can judge, abstract ideas. They have 
 sensations, attitudes, percepts, and memories, but their 
 powers of organization stop short of abstract ideas. 
 
 How one forms an abstraction is extremely difficult to 
 observe through mere introspection. A mind absorbed in 
 studying geometry cannot observe itself at work. That 
 is why abstract geometrical ideas are difficult to explain. 
 Obviously, however, the system of psychology which omitted 
 these would be altogether deficient. 
 
 Higher forms of action. After dealing with the processes 
 of ideation we may very properly come back to a reexam- 
 ination of behavior. Those forms of behavior which are 
 characteristic of mature intelligence are commonly grouped 
 together under the caption '' voluntary choice." The discus- 
 sion of voluntary choice will not duplicate the treatment of 
 reactions and attitudes as indicated on page 66. 
 
 Relation to historic classification. The foregoing classi- 
 fication is to be followed in the following chapters. For the 
 sake of keeping it in some relation with the historic classi- 
 fications, it may be said that the term '' knowledge " is in 
 a measure synonymous with sensation, perception, memory,. 
 
CLASSIFICATION OF CONSCIOUS PROCESSES 69 
 
 and ideation. Feeling and volition are, roughly speaking, 
 synonymous with attitudes, while the higher forms of be- 
 havior classified under voluntary choice are quite synony- 
 mous with the higher phases of volition. The effort should 
 not be made, however, to push this reconciliation of the 
 two classifications too far. There is a large element of 
 effort and hence of volition in every fusion and every 
 formation of an abstraction. There is a large element of 
 feeling in most perceptions. The adoption of a classifi- 
 cation of psychological facts based on studies of nervous 
 processes is a frank abandonment of the historic threefold 
 classification. 
 
 Practical applications. Following the study of the various 
 classes of psychological facts will be certain studies of a 
 practical type which may be termed applications of psy- 
 chology. A part of these applications will be formulated 
 with a view to helping the student to see his own mental 
 processes from a psychological point of view. A part will 
 deal with some of the larger social problems, with a view to 
 showing that community life is capable of proper organiza- 
 tion only through a complete understanding of the nature of 
 human consciousness. 
 
 SUMMARY 
 
 The following summary of the foregoing discussion will serve 
 as a guide to the subsequent chapters : 
 
 I. Sensations 
 
 This will require a description of the sense organs and their 
 action and a description of those aspects of consciousness which 
 come as impressions from the outer world. 
 II. Attitudes 
 
 This will require an explanation of the relation of consciousness 
 to bodily activity and a classification of forms of conscious ex- 
 periences which arise as a result of the individual'^ reactions to 
 impressions. 
 
70 PSYCHOLOGY 
 
 III. Fusions of Sensations 
 
 As sensations become motives or sources of reactions they are 
 united into complexes. These complexes are called percepts and 
 are always present where an individual distinguishes objects in 
 the world about him. 
 
 IV. Memories 
 
 Past experiences are retained in structural changes in the 
 nervous system and either in explicitly distinguishable form or in 
 less obvious character enter into present experience. Psychology 
 must include under this head many facts which escape introspec- 
 tion. Here as elsewhere throughout the discussion the largest 
 regard must be had for the fact that the explanatory prin- 
 ciples of psychology depend on a clear understanding of motor 
 processes. 
 V. Ideas and Ideational Forms of Thought 
 
 These include all the higher forms of organized experience. 
 They are conditioned by the higher complexes which are de- 
 veloped in the cerebral association areas. 
 VI. Voluntary choice is the phrase employed to mark off the highest 
 forms of behavior from the lower forms. The concept of 
 personality enters into this discussion. 
 VII. Applications to individual experience and to social organizations. 
 
CHAPTER V 
 
 SENSATIONS 
 
 Sensations not copies of external forces. For the ordinary 
 man there is no problem for psychology presented by a 
 sensation. A sensation is for his thinking an inner reflec- 
 tion or copy of an external fact. He dismisses as curious 
 speculation any statement which would tend to impair his 
 confidence in the directness of the relation between sensa- 
 tions and external or objective facts. Yet, as was pointed 
 out in an earlier chapter, the progress of science has forced 
 upon us a distinction between objective colors and sounds, 
 on the one hand, and subjective or experienced sensations 
 of color and sound, on- the other hand. For example, color 
 as we see it in our individual experiences is not a form of 
 vibration, while color as the physicist finds that he must 
 describe it in order to explain its physical nature is a form 
 of wave motion easily convertible into other wave motions, 
 such as those of heat, which in turn give us sensations of 
 a sort quite different from colors. 
 
 Laws of sensation as one of the first problems in psychol- 
 ogy. The moment we admit a distinction between subjec- 
 tive color and external light vibrations, certain important 
 scientifix questions immediately suggest themselves. Thus, 
 we are led to inquire what are the laws of subjective color 
 as distinguished from the physical laws of objective light ? 
 For example, in passing from one color in the subjective 
 series to the next color, as from red through orange and 
 yellow to green, we find ourselves taking a series of steps 
 and reaching qualitative differences so marked that we 
 
 71 
 
72 PSYCHOLOGY 
 
 speak of the sensations as opposite or as sharply contrasted. 
 This marked difference in quahties is related to animal 
 interests of a practical sort. Red fruits and green are to be 
 distinguished ; the color of the foliage and of the blossom 
 are to be discriminated. In physics, the transition from the 
 red vibration to the green is one continuous series of changes 
 in rate of vibration. All the vibrations are qualitatively alike; 
 there is no contrast. So far as light vibrations are concerned, 
 they are utterly heedless of animal interests. 
 
 Another example of the difference between the subjec- 
 tive series and the physical series is to be found in the fact 
 that sensations arise only from the middle of certain physi- 
 cal series. Thus the physicist knows that there are rays of 
 light made up of vibrations slower than those which give 
 us sensations of red, and that other rays are more rapid in 
 vibration than those which give sensations of violet. The 
 range of sensations of sound, in like fashion, is short, con- 
 trasted with the series of sound vibrations known to the 
 physicist. 
 
 Relation of sensations to sensory nervous processes. The 
 relation between sensations in consciousness and physio- 
 logical processes in the organs of sense is much closer 
 than is the relation between sensations and the physical 
 facts above discussed. Thus, to take a striking illustration, 
 it is because we have an organ of sense which is affected 
 by light and no special organ affected by weak currents of 
 electricity that men overlooked for so long a period both 
 the prevalence of forms of electrical energy and the close 
 relation between light and electricity. Such an illustration 
 calls attention to the fact that experience differs in certain 
 of its aspects from the physical world, because experience 
 is related to the physical world only indirectly, through the 
 organs of sense. 
 
 Other examples are abundant. When the ear is aroused 
 by the complex sound coming from a drum and a trumpet^ 
 
SENSATIONS v 73 
 
 there are sensations corresponding to each element of the 
 complex because the sensory cells receive the vibrations 
 from one instrument at one point and the vibrations from 
 the other at another point. The two elements of sound 
 do not obliterate each other or cause a blur in conscious- 
 ness. They do not give rise to a single sensation, even 
 though the sound wave which strikes the ear is a single 
 complex air vibration. The further details of this matter 
 will come out in later sections of this chapter. 
 
 Sensations as elements. Our first problem, then, is to 
 study sensations as related to the facts of physics and to 
 the facts of physiology of the sense organs. Later, we 
 shall study sensations in their relation to one another and 
 to the higher forms of experience. It will then be pointed 
 out that sensations as they appear in consciousness are 
 always elements of complex forms of knowledge. There is 
 no such experience as an isolated sensation of red or of 
 green or of sound. All sensations are referred to some 
 point in space ; they are associated with certain interpreta- 
 tions and otherwise brought into the stream of personal 
 experiences. But in all these later combinations, sensations 
 retain their qualitative independence to an extent which 
 justifies us in recognizing them for the purposes of science 
 as elements, or separate and distinct aspects of conscious- 
 ness. The problems of fusion of sensations with each other 
 and the laws of these fusions may therefore properly be 
 postponed ; for the present, we turn to a discussion of sen- 
 sations as elements of consciousness related to certain facts 
 of physics and to the processes in the organs of sense which 
 lie between the physical world and consciousness. 
 
 Psycho-physics as a division of psychology. The field of 
 study which we here enter has sometimes been called 
 psycho-physics. This name originated as the name of one 
 branch of the study of sensations to which our introductory 
 examples have not referred. Psycho-physics in its earlier 
 
74 PSYCHOLOGY 
 
 days studied especially the facts of intensity of sensation. 
 If a physical sound becomes stronger, it does not follow 
 that the related sensations will become stronger in a corre- 
 sponding degree. The facts of intensity will be referred to 
 briefly in our later discussions. 
 
 In taking up the problems of psycho-physics, we shall 
 begin with one of the most highly developed and highly 
 differentiated groups of sensory processes ; namely, those of 
 vision. We might have taken first the simpler sensations, 
 such as those of touch, but the facts regarding color are so 
 much more complex and significant that it will be advanta- 
 geous to encounter at once all the major principles involved 
 in such a study. 
 
 A, Visual Sensations 
 
 Meaning of term ''quality." Visual sensations, like all 
 sensations, can be described only to a person who has 
 experienced them. Red and blue and yellow and black are 
 names of visual sensations. If the reader has had experi- 
 ences corresponding to these words, he will recognize that 
 each of the experiences referred to is a unique fact in his 
 mental life. Red may be like orange or yellow ; it may be 
 soft and pleasing, or glaring and unpleasant ; but its essence 
 is its redness, and this essence, which is' called the quality 
 of the sensation, can be illustrated but cannot be defined in 
 terms of any other experience. 
 
 Chromatic (or color) series and achromatic (or gray) series. 
 If we consider all possible visual sensations, we notice at 
 once that there are two general groups, — those which 
 belong in the series of colors and those which belong in the 
 black-gray-white series. The latter series is in some respects 
 the simpler. Beginning with the darkest black, one may 
 arrange various shades of gray in an unbroken series up to 
 the brightest white. The color series is more complex. It 
 is made up of sensation qualities which, to be sure, shade. 
 
SENSATIONS 75 
 
 into each other through intermediate colors ; but the members 
 of the series have a marked individuality which leads us to 
 designate them by a variety of entirely different names 
 rather than by a common term, such as is used in referring 
 to the gray series. Thus, red and yellow are different quali- 
 ties, though they shade into each other through orange ; 
 when we pass from one to the other, the transition is so 
 marked that we are compelled to describe red and yellow as 
 different qualities. 
 
 Fundamental color names. The question of how many 
 fundamental visual qualities there are, is one that has often 
 been discussed. Popular language has clearly marked out 
 at least four color qualities besides the blacks, grays, and 
 whites. These four colors are red, yellow, green, and blue. 
 The names of these colors are, as their form clearly indi- 
 cates, older than such derived names as orange, indigo, 
 violet, or any of the compound names, such as green-blue 
 and yellow-green. The loose use of the four older color 
 names makes it clear, -however, that there is no particular 
 red or green v/hich can be selected as having exclusive right 
 to the name. In making up a system of color terminology 
 for such works of reference as a dictionary, this fact comes 
 out very clearly. The best that can be done is to take the 
 average of a large number of usages and exhibit a sample 
 of the color chosen. Color names, therefore, while suggest- 
 ing something of the popular discrimination of colors, supply 
 no final evidence as to the number of primary sensation 
 qualities. 
 
 The various scientific studies on this subject of the number 
 of color qualities may be divided into three groups. One 
 group regards red, green, and blue as the only primary 
 colors, all others being looked upon as derived forms. A 
 second group adds yellow, while a third group considers that 
 there are an indefinitely large number, certainly more than 
 four. The solution of the question, since it does not depend 
 
7^ 
 
 PSYCHOLOGY 
 
 Yellow 
 
 Orange 
 
 Red 
 
 Purple 
 
 Green 
 
 Bluish 
 
 Green 
 
 Greenish 
 Blue 
 
 merely upon introspective observation, waits upon the com- 
 plete formulation of certain facts discussed later. 
 
 The color spectrum and circle. More important than the 
 determination of the exact number of primary color qualities 
 is the presentation of a complete description of the series 
 of color experiences. The m.ost complete single series of 
 colors known to physics is produced by passing a pencil 
 of white light through a prism. The different colors which 
 
 compose this ray of 
 white light will be 
 refracted to different 
 positions, and the 
 whole will be spread 
 out into a colored 
 band with red at one 
 end and violet at 
 the other. Between 
 these lie orange, yel- 
 low, green, blue, in 
 the order given. 
 This whole series of 
 colors produced from 
 white light is called 
 the spectrum. Mixed 
 colors are not present in the spectrum, notably purple, which 
 consists of a mixture of red and blue. When purple is intro- 
 duced, the series of colors seems to return upon itself. For 
 this reason, the colors of the spectrum plus purple may con- 
 veniently be represented by a closed figure, either a triangle 
 or a circle. The color circle is given in Fig. 23. Four, or 
 better nine, color names are used to indicate some of the 
 chief qualities of the series, the exact number of such quali- 
 ties being left somewhat indefinite, for reasons indicated 
 above. Between the colors explicitly named in this circle 
 there are transitional forms of sensations. 
 
 Violet 
 
 Blue 
 
 Fig. 23. Color circle 
 
 The center of the circle represents white. All colors 
 
 placed at opposite ends of diameters of the circle 
 
 are complementary colors 
 
SENSATIONS 
 
 77 
 
 Saturation, brightness, and mixtures. There are also 
 transitional forms of sensation from this color series to the 
 gray series. Thus, from any color there is a series of sen- 
 sations in which the color quality gradually fades into a 
 colorless gray of the same intensity as the original color. 
 Such a series is called a saturation series. The full color 
 is said to be a saturated quality ; the more the quality ap- 
 proaches gray, the less saturation it is said to have. Each 
 color is also capable of variations in brightness. A red of 
 
 Fig. 24. Wave forms 
 
 great light intensity is said to have a high degree of bright- 
 ness. A color of small light intensity is said to have a low 
 degree of brightness. The relation of brightness to satura- 
 tion is such that when a color becomes very bright or very 
 dim its characteristic quality tends to disappear. Finally, 
 color qualities may be compounded so as to produce a great 
 variety of intermediate qualities, such as orange-yellow and 
 blue-green, which are sometimes thought of as intermediate 
 qualities, sometimes as equally primary with the others. 
 
78 PSYCHOLOGY 
 
 External light. Turning now from the series of visual 
 sensations, let us review very briefly the characteristics of 
 external physical light. The physicist recognizes physical 
 light as a form of vibration in the luminiferous ether. These 
 ether vibrations have three characteristics ; namely, rate of 
 vibration, amplitude of vibration, and complexity of vibration. 
 For purposes of exposition we may compare light waves to 
 simple water waves, which are represented in outline in 
 Fig. 24. In waves of this type a single particle of water 
 oscillates up and down in straight lines, while the wave as 
 a whole travels in the horizontal direction. 
 
 The rapidity with which each particle oscillates is called 
 the rate of vibration. The rate determines the length of 
 the waves from crest to crest, so that we may refer to waves 
 as having different lengths : rapid vibrations corresponding 
 to short wave lengths, and the slow vibrations corresponding 
 to greater wave lengths. The amplitude of a^ wave is de- 
 termined by the extent of the oscillations of each particle. 
 The complexity of a wave depends on the mode of the 
 movement of the particles ; a complex movement results 
 from the action of a number of wave impulses acting on the 
 same particle at the same time. ° 
 
 The wave forms represented in A, Fig. 24, have like 
 amplitude— that is, like range of movement above and below 
 the horizontal line — but differences in rate, one wave being 
 twice as rapid as the other. The waves in B are alike in 
 rate but different in amplitude. The lines i, 2, 3, 4, 5, 6 
 show the paths of six single particles which participate in 
 the larger wave motion. When a particle is in its original 
 position, it lies at some point along the horizontal line, as 
 at O, At successive periods it moves to the height i, 2, 
 or 3 or to the low level 4, 5, or 6. C represents a complex 
 wave form. The two regular waves, indicated in dotted lines, 
 acting upon the particles together, result in the complex 
 form of vibration represented in the full-drawn line. 
 
SENSATIONS 
 
 79 
 
 Comparison of physical and mental series. In the follow- 
 ing table a comparison is exhibited between the physical facts 
 and the corresponding facts of sensory experience : 
 
 Physical Facts 
 
 Simple light vibrations of medium 
 amplitude 
 
 These simple vibrations appear in 
 every possible rate, thus forming 
 a single continuous series of varia- 
 tions in rate 
 
 These rates vary from less than 
 435 rnillioi^ million vibrations per 
 second 
 
 (435 million million vibrations per 
 second) 
 through all possible rates 
 
 to 769 million million vibrations 
 
 per second 
 and beyond 
 
 Compotcnd vibrations 
 
 The compound sometimes consists 
 of vibrations of about 435 to 500 
 million million per second, com- 
 bined with those of about 660-769 
 million million per second 
 
 In some cases widely different rates 
 are combined, sometimes in special 
 pairs, sometimes in more complex 
 groups 
 
 In some cases various rates other 
 than those above mentioned are 
 combined 
 
 Amplittide variations 
 
 Increase in amplitude to the highest 
 
 Decrease in amplitude to the lowest 
 
 Facts of Sensory Experienxe 
 
 Color sensations 
 
 The sensations differ in certain well- 
 marked stages, forming a series 
 of distinct color qualities, limited 
 in number 
 
 No color experience (sometimes 
 experience of warmth) 
 
 Red 
 
 Successive qualities (yellow, green, 
 
 blue) 
 Violet 
 
 No color experience 
 
 Either whites, grays, less saturated 
 
 colors, or purples 
 Purple 
 
 White or gray 
 
 Various grays and unsaturated colors 
 
 Changes in intensity and saturation 
 Increase in intensity and decrease 
 
 in saturation toward white 
 Decrease in intensity and in satura- 
 tion toward black 
 
8o PSYCHOLOGY 
 
 Relation between the physical and the psychical facts 
 dependent in part on the organs of sense. The differences 
 between the physical series and the sensation series are so 
 striking that much scientific investigation has been devoted 
 to the effort to bridge over the differences, as far as possi- 
 ble, by setting between the two groups of processes described 
 in the above table a third group of processes ; namely, the 
 physiological processes in the eye and central nervous sys- 
 tem. Not infrequently it has been impossible, with the 
 means of scientific investigation in our possession, to dis- 
 cover by direct observation all the physiological links be- 
 tween certain physical facts and certain facts of experience. 
 In such cases, theories have been developed by science to 
 fill the gap. These theories go beyond direct observation 
 in their statements, but do so with definite regard to such 
 facts as can be observed. We turn, therefore, to a con- 
 sideration of some of the physiological facts and theories, 
 taking up, as a necessary introduction to the physiological 
 facts, a study of the structure of the eye. 
 
 Evolution of organ of vision. The human eye is a very 
 complex and highly sensitive organ. It will be well for us 
 in attempting to understand the eye, to go back to an earlier 
 point in the evolutionary series and begin our study with 
 more primitive visual organs. The line of evolution between 
 the simplest eyes and the human eye is not direct, for the 
 human eye is in its sensitive parts a division of the brain 
 brought to the surface of the body. The eyes of inverte- 
 brates show, however, how sensitivity to light first became 
 a specialized function of animal tissue. 
 
 Even in the lowest forms of plant and animal life there 
 is a certain sensitiveness to light. A flower is affected by 
 light, in some cases enough to produce movement on its 
 stem, in all cases in its inner growth conditions. So also the 
 unicellular animal forms are stimulated by light to vigorous 
 action. In the simpler multicellular animals, in addition to 
 
SENSATIONS 8 1 
 
 the differentiation between neural cells and muscular cells 
 which was described in an earlier chapter, there is a further 
 differentiation among the neural cells. In the jellyfish, for 
 example, it is found that at certain points on the surface of 
 the body the cells of the nervous system are grouped into 
 small spots of pigmented cells (see Fig. 25, A), The pig- 
 ment is not a part of the nervous system, but it serves to 
 absorb the light which falls upon this part of the animal's 
 body more than do the unpigmented regions. The result 
 is that the influence of the light is enhanced by the pres- 
 ence of the pigment, and the growth of larger and more 
 sensitive sensory cells in the immediate neighborhood of 
 these spots brings about a condition which is favorable to the 
 reception of light. We may, for convenience, refer to the 
 pigment, since it is not true nervous tissue, as an accessory 
 organ. We shall find in the study of later developments of 
 the eye that the accessory parts of the eye are quite as im- 
 portant as the nervous organs themselves, the evolution of 
 the two groups of structures going on in parallel lines. 
 
 Higher forms of visual organs are represented in Fig. 25, 
 B and C, Thus we find a larger group of cells sensitive to 
 light stimulations. The pigment is present as in the most 
 primitive eyes, and the whole organ is placed in a depression 
 in the surface of the body. This depression serves to protect 
 the delicate cells more effectively than they could be pro- 
 tected on the general body surface, as in the case of the 
 jellyfish. This protection of the cells undoubtedly works to 
 the advantage of the cells, furnishing them the conditions 
 necessary for becoming more sensitive, while at the same 
 time the wall of the depression furnishes them the space in 
 which they become more numerous. In later stages of de- 
 velopment, as indicated in Fig. 25, /) and B, the depression 
 in the body wall is filled with a protecting fluid. This fluid 
 is of a thick, gelatinous consistency, and in the most primitive 
 forms translucent, not transparent. The light stimulation 
 
on 
 
 B 
 
 ^on 
 
 F 
 
 Fig. 25. A series of eyes which have reached various levels of development* 
 
 82 
 
SENSATIONS 83 
 
 which acts upon the sensory cells of such an eye as this 
 will obviously not be very intense or definite. Something 
 has been sacrificed to protection in the fluid, which obstructs 
 the light. This disadvantage is, however, more than offset 
 by the fact that the fluid furnishes favorable conditions for 
 increase in the number and sensitiveness of the cells. Such 
 an eye as this cannot distinguish more than vague changes 
 in illumination. An opaque object passing before the animal 
 might, by its shadow, be recognized as something standing 
 between the animal and the light, but the form or distance of 
 the object certainly could not be recognized except through 
 the intensity of the shadow and the period of its duration. 
 A bright object would give a somewhat more definite im- 
 pression, but nothing comparable to the impression received 
 by the eyes of the higher animals. 
 
 Later stages of development of the eye are represented 
 in the figure. In Fig. 25, D, E, and F, it will be seen that 
 the outer covering of the eyes begins to develop a lens. In the 
 earliest forms, this lens is spherical in shape. Such a shape 
 is mechanically simple, but optically very imperfect. The 
 image which it throws on the sensory surface is distorted, 
 and the different rays of light are focused at different points, 
 causing the hazy colored fringes technically known as chro- 
 matic aberrations. 
 
 Organ of sense as selective organ. Such an evolutionary 
 series as that just described could be made the basis of a 
 chapter on the relations of the animal's inner life and 
 
 * Fig. 25, ^, shows a simple pigment spot. The ordinary epitheHal cells which con- 
 stitute the surface of the body are represented at a. The pigment particles repre- 
 sented at pa make this portion of the surface of the body more susceptible to the 
 action of light. Fig. 25, ^, shows a somewhat more highly developed organ. The 
 surface of the body is here depressed so as to protect the sensory cells. These 
 specialized cells are notably larger than the epithelial cells at aa. This is the eye 
 of Patella. Fig. 25, C, represents the eye of Nautilus. The central cavity is filled 
 with water. Fig. 25, Z>, is a camera eye with a large lens filling its cavity ; op repre- 
 sents the lens. Fig. 25,^, is the camera eye of Murex with the cornea, <:, covering 
 the lens. Fig. 25, F, is the complete eye of cuttlefish with the lens, /; cornea, c\ 
 iris, z, and other portions as before. (From Conn's " Method of Evolution ") 
 
% 
 
 84 PSYCHOLOGY 
 
 development to the outer world of nature. Evidently it is 
 greatly to the animal's advantage to be sensitive to changes 
 in light and thus also to gain indirectly impressions from all 
 objects which reflect or absorb light. The inner life processes 
 are very dependent on these impressions ; therefore, a part 
 of the organism is set aside to keep watch and guide the 
 organism. The organism is thus enabled to select from 
 the world in which it lives those impressions which have to 
 do with its own existence. Furthermore, as we shall find 
 when we come to study other organs of sense, other parts 
 of the body surface are specialized to keep the animal in 
 contact with aspects of the outer world other than light. 
 The organs of sense are accordingly to be defined as special- 
 ized avenues through which forces of the external world 
 that are important to the animal's life affect the organism. 
 
 The human eye — its muscles. We pass over the varying 
 forms of visual organs exhibited in the animal world and 
 take up briefly the human eye. The human eye is an inde- 
 pendent organ separated from the body y^bII and placed in 
 a protecting bony cavity or eye socket. Before taking up 
 the internal structure of the eyeball it may be well to refer 
 to the external muscles which hold it in place and move it 
 about independently of the head. These are important acces- 
 sory organs and increase the range of vision greatly by mak- 
 ing it possible to move the eyes easily without moving the 
 head. The human eye is supplied with six such muscles. 
 By means of these muscles the eye is capable of rotation, 
 with the nicest adjustments in any direction whatsoever. 
 In ordinary life the behavior of one eye is closely related 
 to the behavior of the other eye, so that the muscles coop- 
 erate in producing certain joint movements, or binocular 
 movements as they are called. 
 
 Many of the facts of human vision are closely related to 
 the fact that the eyes are themselves very active organs. 
 Looking at an object involves a great deal of muscular 
 
SENSATIONS 
 
 85 
 
 adjustment. Looking to the left involves a different type of 
 muscular adjustment from that involved in looking straight 
 ahead. These facts should be borne in mind as important 
 for much of our later study. 
 
 The outer wall and the lens. A sectional view showing 
 the internal structure of the eyeball is given in Fig. 26. 
 It will be noted immediately that this organ is in many 
 
 Fig. 26. Diagrammatic section of the human eye 
 
 O, optic ner\-e ; S, sclerotic ; C, cornea ; A, choroid coat ; /, iris ; i?, retina ; V, vitreous 
 
 humor ; H, aqueous humor : L, crystalHne lens ; X, optic center of the lens ; d, blind 
 
 spot ; /, fovea centralis ; /, pupil ; J/, ciliary muscles, which control the curvature 
 
 of the lens ; Od, object outside of eye ; /;;z, image on the retina. (After Wundt) 
 
 respects more highly developed than any of the eyes repre- 
 sented in Fig. 25. By the development of an independent 
 outer wall of cartilage the eyeball has been made a free 
 portion of the body, as noted in the last paragraph. In the 
 second place, it will be observed that the lens, which we 
 saw in some of the lower forms as a spherical organ, has 
 been elaborated in the course of animal evolution, so that it 
 now has the very much more advantageous form of a double 
 convex lens, indicated in the figure at L, This lens has 
 certain other complexities in structure which tend to free it 
 
86 PSYCHOLOGY 
 
 from optical defects. It is not homogeneous throughout ; 
 furthermore, by means of the iris, or adjustable diaphragm, 
 which is placed in front of it, only the center, which is the 
 most efficient portion of the lens, is utilized in ordinary 
 vision. By means of certain muscles which form a circle 
 around the lens and control a transparent capsule which 
 surrounds it, the lens can be modified in form so that it is 
 made more or less convex according as light which is to be 
 focused upon the sensory surface comes from a source near 
 at hand or far away. The details of this adjustment of the 
 lens need not be discussd here ; it is enough to call atten- 
 tion to the fact that when the eye is to look at an object far 
 away, the lens is relatively less convex than when the eye 
 is looking at an object near at hand. The adjustment is 
 carried out reflexly. There are limits beyond which it is 
 impossible for the lens to adjust itself ; the near limit for 
 the normal eye is about eight inches from the eye, the re- 
 mote limit for the normal eye is at an infinite distance. 
 Individual imperfections in adjustment appear. For example, 
 the lens in old age becomes somewhat less elastic than in 
 early life and, because of this lack of elasticity, it is incapable 
 of taking on a high degree of convexity. Other abnormali- 
 ties appear, in that the far limit of certain eyes is at a rela- 
 tively short distance in front of the eye ; a person whose 
 limit of remote vision is thus nearer than a point infinitely 
 far away is described as near-sighted. Most of the defects 
 in the functioning of the lens can be relieved more or less 
 completely by the use of an artificial lens outside of the eye. 
 The function of the artificial lens is exactly that of the lens 
 in the eye, and the possibility of correcting defects in the 
 lens of the eye by various combinations of glass lenses is 
 limited only by the possibilities of physical optics. This 
 makes it perfectly clear that the lens is not to be treated 
 as a part of the nervous system but rather as an accessory 
 organ developed for the purpose of applying the stimulus 
 
SENSATIONS 87 
 
 to the organ of sense in such a way as to produce a clearly 
 defined image on the retina. 
 
 Transparent media. In the human eye all of the media 
 through which the light must pass are highly transparent. 
 A certain portion of the outside coat of the eye — namely, 
 that portion which lies directly in front of the lens — is trans- 
 parent. Between this transparent wall, or so-called cornea, 
 and the lens of the eye there is a chamber filled with trans- 
 parent fluid known as the aqueous humor. The lens itself 
 is of a very high degree of transparency. Back of the lens 
 is a mass of gelatinous matter known as the vitreous humor, 
 which fills the whole eyeball and maintains the proper 
 spherical form of the eyeball. These transparent media are 
 products of evolution and show an important advance over 
 the translucent gelatinous substances which we find in the 
 more primitive eye. 
 
 Choroid coat. The pigment layer which was seen in the 
 most primitive eyes is present in the human eye in the so- 
 called choroid coat. It covers the whole inner surface of 
 the eyeball. It serves the same purpose as does the black 
 lining of a camera ; that is, it prevents the rays of light 
 which have acted upon the sensory surface from being 
 reflected back so as to interfere with other entering rays. 
 It is richly supplied with blood vessels, which provide for 
 the nutrition of the sensory cells. 
 
 The retina. We have, up to this point, referred only to 
 the accessory organs of the eye. We turn now to the exam- 
 ination of the retinal surface, which is the true sensory 
 organ. It is made up of a series of layers of cells dis- 
 tributed over the inner surface of the eyeball and placed 
 between the choroid coat and the vitreous humor. The 
 retinal layer is represented in section in Fig. 27. The rods 
 and cones, which constitute the inner layer lying next to 
 the choroid coat, are undoubtedly the organs which are 
 most immediately affected by the rays of light. The rods 
 
88 
 
 PSYCHOLOGY 
 
 and cones are highly developed cells which are specialized 
 
 for the reception of light stimulations. They may be 
 
 thought of as small ves- 
 sels containing chemical 
 substances which are 
 especially susceptible to 
 changes under the action 
 of light. The chemical 
 activity set up in the rods 
 and cones by the light 
 which enters the eye 
 liberates energy, which 
 is transmitted through 
 the successive layers of 
 cells represented in the 
 figure until, finally, it 
 reaches the large nerve 
 cells of the retina, indi- 
 cated at the level VIII in 
 the figure. The energy 
 which originally entered 
 the eye in the form of 
 vibration in the luminif- 
 erous ether is thus trans- 
 formed into chemical 
 action in nerve cells, and 
 the chemical action in the 
 nerve cells is transmitted 
 to the fibers which pass 
 out of the eyeball and 
 communicate with the 
 central nervous system. 
 Rods and cones and their functions. The rods and cones 
 
 undoubtedly represent different types of receiving organs. 
 
 The central part of the retina, which is more important for 
 
 Fig. 27. A diagrammatic section of the 
 retina 
 
 / is the pigment epithehum, // is the layer of 
 rods and cones. The rods are the small, slender 
 organs. In the retina the rods and cones are, 
 throughout the larger part of the organ, mixed 
 together ; in the fovea only cones appear. ///, 
 IV, V, VI, VII show various intermediate struc- 
 tures between the rods and cones and the nerve 
 cells which are situated at VIII. From the nerve 
 cells at VIII the optic fibers pass out, as indi- 
 cated at IX, toward the blind spot, where they 
 leave the eyeball. X represents the limiting 
 membrane of the retina. A ray of light entering 
 the eye passes through the retina in the direc- 
 tion from X to //. The light does not produce 
 any effect upon the cells or fibers until it reaches 
 the layer of rods and cones. (After Greeff) 
 
SENSATIONS 89 
 
 clear vision than other portions, is made up of cones exclu- 
 sively. Passing from this limited central region of clear 
 vision, known 2i% \ki^ fovea centralis, toward the outer areas, 
 or periphery, of the retina, the rods become more and more 
 numerous. The functional differences which correspond to 
 these structural facts can be easily observed. Let a colored 
 light of moderate size and intensity be brought into the 
 outer part of an observer's field of vision. This light will 
 cast its image on the periphery of the retina where the rods 
 predominate, and the observer will not experience a color 
 sensation but rather a sensation of colorless light. If, now, 
 the colored light is gradually made to approach the center 
 of clear vision where the cones predominate, its color quality 
 will become more and more obvious, until, finally, at the 
 center of clear vision it will be clearly seen. We may state 
 this result in general form by saying that the center of clear 
 vision is also the center of color vision, while the areas at 
 the extreme periphery of the retina are totally color blind. 
 The areas intermediate between the extreme periphery of 
 the retina and the center of clear vision are partially color 
 blind ; that is, they respond to a limited number of colors. 
 This limitation of ability to respond to colors is offset in 
 the rods by a distinct advantage on the side of susceptibility 
 to slight changes in colorless light. An observer very fre- 
 quently has the experience early in the evening of seeing a 
 faint star in the outer edge of the field of vision, and finds 
 the moment he turns to look directly at the star that it is 
 impossible to see it. The periphery of the retina was suffi- 
 ciently sensitive to the slight illumination to make possible 
 a sensation from the faint star, whereas the center of the 
 retina was incapable of responding to this slight illumina- 
 tion. The significance of this differentiation of the retina in 
 the development of the animal kingdom is evident. The 
 periphery of the retina and the extreme edges of the field 
 of vision do not have the same significance for the animal 
 
90 PSYCHOLOGY 
 
 as the center. It is more advantageous that the animal should 
 be able to concentrate its highest forms of nervous activity 
 upon a limited area. On the other hand, it is important that 
 the outer regions of the retina should be sensitive in such 
 a way as to give immediate warning of any changes in illu- 
 mination, for changes in illumination mean movement, pos- 
 sibly the approach of danger, and this should be recognized 
 sufficiently to warn the observer. If, then, it is desirable to 
 give the object stricter attention, the eye can be turned so as 
 to bring the image upon the center of clear vision. 
 
 Color blindness. The differentiation between the different 
 parts of the retina, which has just been described as charac- 
 teristic of the normal retina, does not always appear. There 
 are certain persons whose eyes are not fully responsive 
 to colors ; these persons have at the center of the retina a 
 condition similar, at least so far as color processes are con- 
 cerned, to that which appears toward the periphery of the 
 normal retina. This inability to respond to different color 
 stimulations may in some cases be complete, so that the 
 individual sees the world as a normal individual sees an 
 engraving ; that is, as if it were made up only of differences 
 in light and shade without the quahtative differences which 
 we describe as color differences. A much larger number 
 of individuals have a partial deficiency, analogous to that 
 which appears in the intermediate zones of the normal 
 retina. The various forms of partial color blindness are 
 extremely difficult to define with precision, for the simple 
 reason that the color sensations of the partially color-blind 
 individual constitute his world of color sensations. He 
 usually has no means of comparing his experiences with 
 those of the normal individual. His efforts to describe his 
 own experiences to a normal individual are complicated 
 by the necessity of using terms devised for the normal 
 individual rather than for his own peculiar experiences. 
 Fortunately for science, there have been a few cases in 
 
SENSATIONS 
 
 91 
 
 which the same person has been able to observe directly 
 both the normal color sensations and the partially color- 
 blind series. The defect in such individuals appears only 
 in one eye, while the other eye is of the normal type. It 
 has, furthermore, been possible by certain methods of com- 
 paring color mixtures to make an analysis of other cases of 
 color blindness. The net result of these investigations has 
 been to show that the color series of a partially color-blind 
 individual is of a simpler type than that of the normal in- 
 dividual with a fully developed retina. One very common 
 form of partial color blindness, known as ''red-green blind- 
 ness," has been thoroughly investigated. The following 
 table shows the comparison between the normal color system 
 and the two types of red-green blindness, which have been 
 worked out : 
 
 NORxMAL 
 
 Type I 
 
 Type II 
 
 Red 
 
 The red end of the spec- 
 
 Yellow 
 
 
 trum short ; what is seen 
 
 
 
 is gray, or unsaturated 
 
 
 
 yellow 
 
 
 Orange 
 
 Unsaturated yellow 
 
 Unsaturated yellow 
 
 Yellow 
 
 Unsaturated yellow 
 
 Unsaturated yellow 
 
 Green 
 
 Yellow 
 
 Gray, or unsaturated yellow 
 
 Blue 
 
 Blue 
 
 Blue 
 
 Violet 
 
 Violet 
 
 Violet 
 
 Such facts as are shown in this table and in the cases 
 of total color blindness emphasize the intimacy of the rela- 
 tion between retinal development and the development of 
 experience. They make it clear that the number of sensa- 
 tion qualities which an observer can distinguish depends 
 not on the number of physical processes in the outer 
 world but on the number of physiological processes which 
 are aroused in the nervous system by the various kinds of 
 physical energy. 
 
92 PSYCHOLOGY 
 
 Color-mixing. Another group of facts closely related to 
 those discussed above are the facts of color-mixing. If a 
 given point on the retina is stimulated at the same time by 
 two or more rays of differently colored light, the chemical 
 process set up cannot be the process which is appropriate 
 to either color acting alone. Experience shows that the 
 process is a compromise between the processes which would 
 have resulted if each ray had acted alone. Thus, if at the 
 same moment a ray of red light and a ray of yellow light 
 fall upon a single cone, the result is that the observer sees 
 orange, which corresponds in quality to the color lying in 
 the spectral series intermediate between red and yellow. If 
 instead of merely using red and yellow we use red, yellow, 
 and blue at the same time, we find, by observing the result- 
 ant sensation, that a compromise between the three chemical 
 tendencies in the cone is very different from any one of the 
 processes taken alone. Indeed, in such a case the retina 
 is not capable of giving a compromise color process, but 
 falls back into the process which the study of color blindness 
 shows to be the most primitive form of chemical activity ; 
 namely, the chemical process corresponding to gray, which 
 we found as the only process in the eye of the totally color- 
 blind person and in the periphery of the normal retina. 
 When all the colors of the spectrum fall at one time on a 
 cone, as in full daylight, the result is a sensation of pure 
 brightness or white. 
 
 If a red ray is mixed with a blue ray, a unique compromise 
 process results, which is not directly related to any of the 
 simple colors of nature ; namely, the process which gives 
 rise to a purple sensation. Purple is a color quality which 
 can be explained only in terms of the retinal process. Red 
 and blue, which are the physical facts conditioning the ex- 
 perience of purple, are at the extreme ends of the physical 
 spectral series, yet they cause in the retina a single process 
 which gives the sensation quality purple. This goes to show 
 
SENSATIONS 93 
 
 that the retinal processes for red and blue are closely related 
 in character, in spite of the great difference in the respective 
 rates of vibration in the physical processes which excite 
 these retinal processes. The color circle, which was described 
 in an earlier paragraph, is therefore not to be explained as 
 a physical circle but as a circle of retinal processes and 
 corresponding experiences. Indeed, it may be said in gen- 
 eral that the laws of color-mixing are primarily laws of retinal 
 behavior rather than laws of the physical world. The fact 
 that all the colors of the spectrum when mixed together 
 produce gray is, as has been pointed out a number of times, 
 a physiological fact and a fact of experience rather than a 
 fact of physical vibrations. 
 
 The principles of color mixtures were worked out first by 
 physicists and have furnished a basis for most of the theories 
 of color vision. Briefly stated, the general principles of 
 color-mixing are as follows : When two colors near each 
 other in the spectral series enter the eye at the same time, 
 there results a sensation and a retinal process which is inter- 
 mediate to those demanded by the two colors when they act 
 alone upon the retina. This intermediate process is not the 
 same as that which would result from stimulation of the 
 retina by the intermediate pure color, for the sensation is 
 not as fully saturated as it would be if it had resulted from 
 the action of a pure color. As the distance between the two 
 colors of the mixture is gradually increased, the chromatic 
 quality of the resultant grows less and less marked, until 
 finally the sensation is of the simplest possible type ; namely, 
 the sensation gray. This shows that the retina is forced 
 by certain mixtures of very different colors to return to the 
 simple undifferentiated form of activity which characterized 
 it before the differentiation into chromatic qualities began. 
 Two colors which are opposed to each other in such a way 
 that they give when mixed no color whatsoever, but merely 
 the sensation gray, are known as complementary colors. 
 
94 PSYCHOLOGY 
 
 If the distance in the color circle between two colors which 
 enter into a mixture is greater than that required for the 
 complementary effect, the resulting color will be some shade 
 of purple. If purple is introduced in the color circle, there 
 is no shade of color which does not have its complement. 
 The color circle shown in Fig. 23 may be made, therefore, 
 the basis for discussion of complementary pairs, provided the 
 arrangements of the colors opposite each other are made 
 with this end in view. If more than two colors are mixed, 
 the total result will be the sum of the partial effects and 
 can be foreseen by considering the partial processes as if 
 they occurred successively. 
 
 Pigment-mixing subject to physical law. It may be well 
 to call explicit attention to the fact that the statements here 
 made regarding color mixtures do not apply to mixtures 
 of pigments. The mixture of pigments is a physical fact, 
 not a physiological process. The action of pigment on light 
 is to absorb certain rays and reflect others. Mixtures of 
 pigments affect light in a complex way, and hence produce 
 results which cannot be explained by merely inspecting the 
 separate pigments. 
 
 A single case of pigment-mixing may be taken as an ex- 
 ample. Thus, if yellow and blue pigments are mixed, they 
 produce an impression of green. This result is due to the 
 fact that the yellow pigment absorbs a good deal of light 
 and reflects only those colors which are near it in the spectral 
 series. Blue does the same. The only color which survives 
 the joint absorptions of yellow and blue pigment particles is 
 green, for green is reflected in a measure by both yellow 
 pigment particles and by blue. The fact that green results 
 in this case calls for an explanation ' absolutely different 
 from that which applies to the gray which results from the 
 mixture of yellow and blue light. 
 
 After-images. The consideration of certain other facts is 
 necessary to complete the discussion of visual sensations. 
 
SENSATIONS 95 
 
 If light acts upon a retinal element for a given period, the 
 effect will continue for a time after the external light ceases 
 to act. The observer will notice what is known as an after- 
 image of the light at which he has been looking. Every- 
 one has doubtless observed the vivid after-images which 
 result from looking at the sun or other very bright objects. 
 Most of the after-images which we receive from ordinary 
 objects are so faint that they are overlooked, unless special 
 effort is made to notice them and to retain them. In gen- 
 eral, the experience which continues after the withdrawal of 
 the external light resembles only for a very brief interval the 
 sensation originally produced by the external light. So long 
 as the original impression and after-image are of the same 
 quality, the observer is said to have a positive after-image. 
 An example of such a positive after-image can easily be 
 secured by rapidly rotating a burning stick in a circle, when 
 the observer will see an uninterrupted circle of light, because 
 the stimulus returns to each of the points of the retina 
 before the original process has had time to change. Very 
 soon after the external stimulus is withdrawn, experience 
 undergoes a radical change. The general principle of this 
 change may be described by saying that every black changes 
 to white, every white to black, and every color to its comple- 
 ment. Since these changes are known from the conditions 
 to be due to physiological processes rather than to external 
 light, we describe the conditions for these after-images in 
 the following terms : The retina tends to set up as soon as 
 possible a process opposite to that which was produced by 
 the original stimulus. This chemical process, opposite in 
 character to that produced by the external stimulus, is due 
 to the tendency of the physiological organism to restore the 
 chemical substances which have been used up in the first 
 process of stimulation. The experience of the observer fol- 
 lows, during this process of recuperation, the retinal activity 
 rather than the external physical fact. Thus, after looking 
 
96 PSYCHOLOGY 
 
 for a time at a brilliant red light, the observer sees very 
 soon after the light is withdrawn a colored area of like 
 spatial form and extent as the original but of a quality ex- 
 actly complementary to the red ; namely, blue-green. In like 
 fashion, the negative after-image of a blue surface is yellow. 
 If the stimulating surface is black and white or gray rather 
 than colored, the negative after-image will be of such a 
 character that what was bright in the original image will ap- 
 pear dark in the after-image, and, conversely, what was dark 
 in the original image will appear white in the after-image. 
 
 Contrasts. After-effects in the retina very frequently 
 operate to modify the retinal processes produced by subse- 
 quent light stimulations. For example, let an observer who 
 has been looking steadily at a bright red light for a time 
 and has a strong tendency toward a green after-image look 
 at a blue surface ; the blue surface will not be seen in its 
 normal color, but will be seen as a mixture of blue and 
 green, the green being contributed in this case by the after- 
 image process in the retina. The mixtures between after- 
 effects and color stimulations here under discussion give 
 rise to many forms of color contrast. In view of the con- 
 tinual movement of the eye from point to point in the 
 field of vision, the observer is always carrying more or 
 less marked after-effects from a given part of the field of 
 vision to the neighboring parts. If, for example, a red and 
 a green field are placed in close juxtaposition, and the eye 
 after looking at the red surface tends to move in such a 
 way as to bring a portion of the retina which has been 
 stimulated by the red into a position such that it will 
 be stimulated by the green light, the green sensation re- 
 ceived from the summation of the external stimulation and 
 the after-im.age will be more intense than a green sensation 
 received without the preliminary stimulation from a red. 
 The result is that green seems to be more saturated when 
 it lies near red. In general, every color is emphasized by 
 
SENSATIONS 97 
 
 being brought into close relation with its complementary, 
 and grays tend to take on colors complementary to sur- 
 rounding fields. This effect appears even when no eye 
 movements can be detected. There is probably a diffusion 
 of contrast effects through the retina even when the eye 
 fixates steadily a single point. 
 
 The tendency of grays to take on colors may be well 
 illustrated by shadows. If a field w^hich is illuminated by a 
 yellow light is interrupted by a shadow which is, in reality, 
 gray, this gray shadow will take on a bluish tinge by con- 
 trast with the yellow field. This fact has long been observed 
 by those who reproduce the colors of nature in painting, and 
 the shadows in painting will usually be found to be, not 
 reproductions of the physical facts, but rather reproductions 
 of the impression made upon the observer. 
 
 Theories of color vision. It remains to add a few remarks 
 concerning the less certain conclusions regarding the rela- 
 tion between light sensations and external ether vibrations. 
 The effort has frequently, been made to describe the physi- 
 ological processes in a single comprehensive formula or 
 theory, which shall include all the facts. No attempt will 
 here be made to review all of those theories. It wdll be 
 enough to present one of the simplest and most sug- 
 gestive, and leave it to the student to criticize and recon- 
 struct it in the light of the facts discussed above and 
 reviewed in the tables given below. 
 
 Mrs. Franklin's genetic theory of processes in the retina. 
 The theory which was formulated by Mrs. Franklin is as 
 follows : The primitive retina of the lower animals and the 
 periphery of the human retina have only one chemical 
 process with which to respond to all light stimuli. This 
 single chemical process, when set up through the action 
 of light, arouses in the central nervous system a process 
 which is the condition of a gray sensation. This is the 
 original undifferentiated type of retinal activity. As the 
 
98 PSYCHOLOGY 
 
 evolution of the retina goes forward, this original chemical 
 process, which may be called the gray process, is so subdi- 
 vided that colors produce certain partial phases of the 
 original chemical activity. The partial chemical activities 
 produce each a specialized form of nervous process and 
 a specialized form of sensory experience. The breaking up 
 of the gray process into special color processes begins with 
 a development, first, of the partial processes which corre- 
 spond on the one hand to blue, and on the other hand to 
 orange or yellow, sensations. This first differentiation cor- 
 responds to the wide difference between the extreme ends 
 of the spectral series. The original gray process does not 
 disappear with the rise of the blue and yellow processes, 
 but remains as the neutral and more general form of 
 response. At this stage the yellow and blue processes are 
 each called out by a great variety of stimulations. Thus, 
 the yellow process is aroused by red light, orange light, and 
 green light, as well as by yellow light. As the development 
 goes on, the yellow chemical process is subdivided into 
 more highly specialized processes, corresponding to red 
 and green. The result of this successive differentiation of 
 process is that the highly organized retina may, when 
 stimulated by the appropriate form of light vibration, re- 
 spond with specialized chemical processes to red, green, 
 yellow, or blue. If yellow and blue, which were the first 
 forms of light to arouse differentiated processes, act at the 
 same time upon the retina, the partial processes which are 
 differentiated out of the gray cannot both be in action at 
 once without being swallowed up in the original funda- 
 mental process of gray. If red and green act together upon 
 the retina, the yellow process appears as the more funda- 
 mental form of chemical process. The facts of color blind- 
 ness can be explained by stating that the differentiation of 
 chemical processes is not complete in the color-blind eye. 
 Negative and complementary after-images are due to the 
 
SENSATIONS 
 
 99 
 
 physiological instability of the partial chemical substances 
 left in the retina after a process in which a colored light 
 has partially disintegrated the retinal substance. Contrast 
 has been included by earlier discussions under the same head 
 as after-images, though by a spread of stimulation effects con- 
 trasts appear where there are no immediate after-images. 
 
 The student will see at once that many of these statements 
 are hypothetical. They serve, however, to gather together the 
 facts, and they give a genetic account of primitive as w^ell 
 as of present retinal conditions. The theory or hypothesis 
 should be clearly distinguished from the facts, and yet it is 
 evident that the facts justify us in attempting to explain the 
 relation between physical processes and conscious processes 
 by something which goes on in the retina. In order to keep 
 the facts clearly in the foreground, it may be well to re- 
 turn to a general summary of the different groups of facts 
 discussed in this section. 
 
 SUMMARY TABLES 
 
 TABLE A. COLOR BLINDNESS 
 
 Physical Facts 
 
 Physiological Processes 
 
 Sensations 
 
 L 
 
 Full series of 
 
 Highly developed retina 
 
 A differentiated group 
 
 
 simple vibrations 
 
 with, however, a limited 
 
 of sensation quali- 
 
 
 
 number of modes of re- 
 
 ties including all 
 
 
 
 sponse to external light 
 
 colors 
 
 IL 
 
 Full series of 
 
 Partially developed retina 
 
 Partial color blindness 
 
 
 simple vibrations 
 
 with a number of possibili- 
 ties of response to exter- 
 nal stimulation which is 
 more limited than in the 
 normal retina 
 
 
 IIL 
 
 Full series of 
 
 Retina so little developed 
 
 Total color blindness 
 
 
 simple vibrations 
 
 as to have only one mode 
 of response 
 
 
lOO 
 
 PSYCHOLOGY 
 
 TABLE B. COLOR MIXTURES 
 
 Physical Facts 
 
 Physiological Processes 
 
 Sensations 
 
 I. 
 
 Series of simple 
 
 Highly developed retina 
 
 Limited number of 
 
 
 vibrations 
 
 with a limited number of 
 
 sensation qualities. 
 
 
 
 distinct modes of response 
 
 constituting a series 
 of distinct qualities 
 
 IL 
 
 Two simple 
 
 Retinal response which 
 
 Single color sensa- 
 
 
 waves, closely re- 
 
 compromises between the 
 
 tion somewhat less 
 
 
 lated in number 
 
 two responses which 
 
 saturated than in 
 
 
 of vibrations, en- 
 
 would have resulted had 
 
 the simple series 
 
 
 tering the eye 
 
 the two vibrations acted 
 
 
 
 together, thus 
 
 separately 
 
 
 
 making a com- 
 
 
 
 
 pound wave 
 
 
 
 III. 
 
 Two simple 
 
 Retinal response which 
 
 A color very little 
 
 
 waves, very dif- 
 
 tends to take the simplest 
 
 saturated, or a 
 
 
 ferent in number 
 
 and most general form of 
 
 single purple or 
 
 
 of vibrations, en- 
 
 retinal behavior 
 
 gray _ 
 
 
 tering the eye 
 
 
 
 
 together, thus 
 
 
 
 
 making a com- 
 
 
 
 
 pound wave 
 
 
 
 IV. 
 
 Large numbers 
 
 Simple response of the rudi- 
 
 Gray 
 
 
 of waves en- 
 
 mentary type 
 
 
 
 tering the eye 
 
 
 
 
 together, thus 
 
 
 
 
 making a most 
 
 
 
 
 complex wave 
 
 
 
 TABLE C. AFTER-IMAGES AND CONTRASTS 
 
 Physical Fact 
 
 Physiological Process 
 
 Sensation 
 
 I. Strong light vibra- 
 
 Response followed ,by a 
 
 Color sensation con- 
 
 tion followed by 
 
 continued action of the 
 
 tinuing after exter- 
 
 the withdrawal of 
 
 retina and a final reversal 
 
 nal light and then 
 
 physical light 
 
 of the retinal process to 
 
 changing into com- 
 
 
 restore the tissue to its 
 
 plementary color 
 
 
 normal condition 
 
 quality 
 
SENSATIONS lOl 
 
 B, Auditory Sensations 
 
 The task of defining sound sensations and of describing 
 their conditions will be a comparatively simple one on the 
 basis of the elaborate study already made of visual sensations. 
 
 Physical sound. The physical stimulus which causes the 
 nervous processes, which, in turn, condition auditory sensa- 
 tions, consists of longitudinal air vibrations. When a vibrat- 
 ing body strikes the air particles about it as it vibrates 
 backward and forward, the air particles are alternately driven 
 together and rebound from one another. Successive waves 
 of condensation and rarefaction result, and these waves are 
 carried forward in all directions until they strike some re- 
 ceiving surface, such as the ear. These air vibrations can 
 be defined in the same terms of rate, amplitude, and com- 
 plexity as were used for the light vibrations in the preceding 
 section (p. J J), although it should be noted that the form of 
 vibrations is different in the two cases. 
 
 Pitch, or tonal quality. With regard to the relation 
 between sensation and external sound vibration, it is to 
 be said, first, that when the objective waves are regular, 
 they give rise to experiences of tone ; when the vibrations 
 are irregular, the resulting sensation is one of noise. The 
 rates of the regular vibrations which are recognized as tones 
 are directly related to differences of pitch. Middle C on the 
 piano scale has a rate of vibration of two hundred and fifty- 
 six double vibrations per second. Toward the bass end of 
 the scale the vibrations decrease in rapidity, while toward 
 the treble they increase. The lowest rate which is ordinarily 
 heard by the normal ear is about thirty-two vibrations per 
 second, although rates of sixteen, or even ten, per second 
 have been described by some observers as audible. At the 
 upper end of the scale one can hear vibrations of thirty 
 thousand to forty thousand per second. Sounds produced 
 by insects are of this order. 
 
I02 PSYCHOLOGY 
 
 Intensity, or loudness. Intensity of tone varies according 
 as the amplitude of vibration of the single air particles is 
 great or small. 
 
 Complexity of a regular type the source of differences in 
 timbre. Ordinary sensations of tone are produced by com- 
 plex waves. If two or more forms of vibration are transmitted 
 to a given particle of air at the same moment, the particle 
 will move in a path which is the resultant of all of the dif- 
 ferent paths through which it would have moved had the 
 various impulses of vibration acted upon it successively. 
 When one compares a given tone from the piano with the 
 tone of the same pitch from a violin, he will recognize that 
 the characteristics of the tones are different, though they 
 are of the same pitch. The violin string vibrates not only 
 as a whole but also in certain sections, and the piano wire 
 vibrates as a whole and at the same time in sections. The 
 rates of vibration of the string and wire as wholes may be 
 exactly the same. The sections in the two cases and the 
 rates of their vibration will nearly always be different. The 
 result is that any particle of air set in motion by either 
 piano wire or violin string will have its main path deter- 
 mined by the vibration of the whole wire or string, while 
 the minor details of vibration will be determined by the 
 vibrations of the sections of the wire or string. The phase 
 of tonal quality thus determined by the complex of minor 
 vibrations is known as timbre. The main, or fundamental, 
 tone is modified by the minor higher tones, or overtones as 
 they are called. Tones of the same pitch derived from vari- 
 ous instruments have various timbres, just in so far as they 
 have different overtones. 
 
 Noise due to irregular vibrations. The experience of 
 noise is dependent upon a form of vibration which is so 
 complex as to be highly irregular. A vague regularity ap- 
 pears in most noises. We speak, accordingly, of certain 
 noises as low and rumbling, and of others as high and shrill, 
 
SENSATIONS 103 
 
 but for the most part the tendency toward regularity of 
 vibrations gives way in noises to a confusion of irregular 
 oscillations in the air particles. 
 
 Evolution of the ear. Turning from the physical stimulus 
 to the auditory organ, we find here, as in the case of the 
 eye, that by a long process of evolution there has been pro- 
 duced a sensory organ which has a variety of accessory parts 
 and a delicate sensory surface, which latter transforms the 
 air vibrations into nervous processes. The most primitive 
 ear, such as is found in the coelenterates, consists in a sack- 
 shaped opening in the side of the body. This sack-shaped 
 depression, or vesicle, contains hard calcareous particles, and 
 is lined by sensitive cells which are similar in their general 
 appearance to the cells in the primitive eye. The whole 
 organ can be easily explained by comparing it to a child's 
 ordinary rattle-box. If the animal is shaken, or if any 
 sound vibrations strike against the wall of the vesicle, the 
 calcareous particles, or otoliths as they are called, are set 
 in motion and tend to strike against the sensitive cells. The 
 result is that the cells will be stimulated by each movement 
 of the animal's body or by the vibrations which enter the 
 vesicle. As the ear develops through the animal series 
 there appear a number of accessory organs which serve to 
 facilitate the reception of vibrations, and there comes to be 
 a division between the tw^o original functions of the ear ; 
 namely, that of sensory response to the movements of 
 the body as a whole, and that of response to vibrations 
 from the water or air. 
 
 The human ear, pinna, and meatus. After this brief 
 reference to the primitive ear we may turn immediately to 
 a description of the human ear. The outer cartilaginous 
 organ, known as the pinna, has in man very little function. 
 It serves in a rudimentary way to concentrate the sound 
 waves and direct them toward the inner ear. The long 
 funnel-shaped pinna of a horse's ear serves a function which 
 
104 
 
 PSYCHOLOGY 
 
 has been lost in the process of evolution. By moving its 
 ear the horse collects sounds from different directions, and 
 thus becomes very acutely sensitive to sound and at the 
 same time recognizes the direction from which the sound 
 comes. But the horse loses fine qualitative shades of sound 
 
 ET 
 
 Fig. 28. Diagrammatic section showing the structure of the ear 
 
 P, external pinna ; EM^ external meatus ; T, tympanic membrane ; /, internal 
 meatus, or tympanic cavity. Extending from the tympanic membrane to the inner 
 ear there are three bones constituting the chain of ossicles : malleus, incus, and 
 stapes. ET, Eustachian tube, passing from the internal meatus to the cavity of 
 the throat ; SC, one of the three semicircular canals ; AN^ the auditory nerve, 
 which divides into four parts as indicated in the figure, one branch connecting with 
 the semicircular canals, two with the parts of the vestibule, and the fourth with the 
 core of the cochlea, C. The canals of the cochlea are indicated in general outline ; 
 for details see Fig*. 30. The vestibule is the general region lying between the canals 
 
 and the cochlea. (Modified from Czermak) 
 
 because the funnel modifies in some measure the form of 
 the air vibrations. The human ear has so evolved that it 
 interferes little with quality. This shows that the sense of 
 hearing in man is not a locating sense but a sense devoted 
 to the finest discriminations in quality. The evolution of the 
 ear is undoubtedly related to the evolution of speech. 
 
SENSATIONS 105 
 
 The cylindrical canal which connects the surface of the 
 body with the inner cavities of the ear is known as the ex- 
 ternal meatus. This canal is liberally supplied with protective 
 bristles, and with secretory glands which tend to protect the 
 ear from all foreign particles, and it is curved in shape so 
 that nothing but very small, slender objects can penetrate 
 to the inner parts of the ear. 
 
 Nature has a relatively easy problem of protection of deli- 
 cate organs in the case of the ear because air vibrations can 
 be conducted along a narrow passage. In the case of the 
 eye, the organ must lie exposed on the surface of the body. 
 Nature has put a ring of bony structures around the eye, 
 but the protection of the ear is much more complete. 
 
 The tympanic membrane. The inner end of the external 
 meatus is closed by means of a circular membrane, known 
 as the tympanic membrane. This tympanic membrane is a 
 composite membrane made up of circular and radial fibers. 
 It is slightly depressed in the middle so as to be somewhat 
 funnel-shaped and is loaded by being connected on its inner 
 surface with a small bone, known because of its shape as 
 the malleus, or hammer. The malleus is controlled by a 
 small muscle, known as the tensor tympani. When this 
 muscle is contracted it draws the malleus inward, and with 
 the malleus the tympanic membrane, thus increasing the 
 tension of the membrane and emphasizing its funnel-shaped 
 form. The adjustments of the tympanic membrane, as w^ell 
 as its shape, are of importance in giving the ear the largest 
 possible range of ability to receive sound vibrations. No 
 artificially constructed diaphragm, such as those employed 
 in the phonograph or telephone, is capable of as wide a 
 range of response to tones as is the adjustable, complex 
 diaphragm in the ear. 
 
 Air chamber on inner side of the tympanic membrane. 
 In the functioning of the tympanic membrane a difficult 
 mechanical problem arises, because the air pressure in the 
 
io6 PSYCHOLOGY 
 
 external world is constantly undergoing changes. With every 
 change in the barometric pressure there would be an inter- 
 ference with the action of the tympanic membrane, if the 
 spaces behind this membrane were air-tight. Nature has, 
 accordingly, provided on the inner side of the tympanic 
 membrane an air chamber com.municating with the atmos- 
 phere so that any change in atmospheric pressure will result 
 in an equal change in the pressure on both sides of the 
 tympanic membrane. This air chamber on the inner side 
 of the tympanic membrane is known as the internal meatus, 
 or tympanic cavity. It consists of an irregular cavity in the 
 bone, which is in communication with the throat by means 
 of a small canal, known as the Eustachian tube. The wall 
 of the Eustachian tube is flexible, so that it collapses except 
 when a current of air is forced through it by a change in 
 pressure, either in the internal meatus or in the external 
 atmosphere. For this reason, the ordinary voice vibrations 
 which arise in the throat are not communicated directly to 
 the internal meatus. 
 
 Chain of ossicles. Since there is an air chamber on the 
 inner side of the tympanic membrane, there must be some 
 means of carrying the sound vibrations received on the tym- 
 panic membrane across this cavity to the inner ear. The 
 means for transmitting the vibrations received by the tym- 
 panic membrane consist of a chain of three small bones, 
 known as the chain of ossicles. The first of these ossicles 
 has been mentioned ; it is the malleus, or hammer, which 
 is attached by its long arm to the middle of the tympanic 
 membrane. The head of the malleus articulates with the 
 surface of the second bone, which is known as the incus 
 because of its anvil-shaped appearance. One of the branches 
 of the incus articulates in turn with the third bone, known 
 as the stapes, or stirrup. Any vibration received by the tym- 
 panic membrane is thus communicated to the stirrup. The 
 stirrup fits into an oval opening, known as the fenestra 
 
SENSATIONS 107 
 
 ovalis, which leads into the inner ear. The stapes is con- 
 nected with the walls of this fenestra ovalis by means of 
 a membrane, so that it constitutes a tight-fitting piston 
 which can move backward and forward in the fenestra 
 ovalis. Beyond the oval window the inner ear is filled in 
 all of its parts with lymphatic fluid. Sound vibrations, 
 which are originally vibrations of air particles, are thus 
 transformed by the mechanism described into vibrations in 
 the lymphatic fluid which fills the inner ear. 
 
 The inner ear. The inner ear is divided into three prin- 
 cipal parts : vestibule, semicircular canals, and cochlea. The 
 vestibule is an irregular ovoid cavity about one fifth of an 
 inch in diameter, which opens on the one side into the snail- 
 shell-shaped cavity, known as the cochlea, and on the other 
 into a system of slender canals, known as the semicircular 
 canals. The vestibule itself is divided into two parts, known 
 as the saccule and utricle. 
 
 The semicircular canals. The semicircular canals are not 
 organs of hearing. They are organs which have taken up 
 in the process of evolution that function of the primitive 
 ear which was concerned with response to the grosser move- 
 ments of the animal's whole body. There are three of these 
 canals, and they lie in such positions that each one occupies 
 a different plane in space. Any change in the position of 
 the head, or of the body as a whole, will cause a redistri- 
 bution of the pressure within the system of canals, and this 
 change in pressure affects the nerve cells which are distrib- 
 uted in the wall of the enlarged portion, or ampulla, of 
 each canal. The whole system of canals serves as an organ 
 of equilibration. The sensory stimulations which come from 
 this organ do not give rise in developed human beings to 
 clearly differentiated sensations. The result is that the ordi- 
 nary observer does not know that he has a special sense 
 organ of equilibration. The stimulations are for the most 
 part taken up by the lower centers of the nervous system, 
 
io8 
 
 PSYCHOLOGY 
 
 Fig. 29. Diagrammatic 
 
 section of the sensory 
 
 cells in the vestibule 
 
 The receiving cells are 
 situated on the surface, as 
 represented by S. These 
 receiving cells are sur- 
 rounded by supporting 
 cells, as indicated at A. 
 The nerve fiber is distrib- 
 uted among the receiving 
 cells. The true sensory cell 
 at G is in the ganglion, 
 rather than directly at the 
 surface. This sensory cell 
 sends its second fiber in- 
 ward to the central nervous 
 system, represented by C. 
 (After Herrick) 
 
 where they are distributed to the mus- 
 cles which keep the body erect ; they 
 probably never reach the higher regions 
 except in company with a great mass 
 of other excitations, such as touch sen- 
 sations from the soles of the feet and 
 muscle sensations from the neck and 
 trunk. When they become excessively 
 intense they give rise to the experience 
 of dizziness. In some cases the indirect 
 effects of their action come into con- 
 sciousness. When the reflex muscular 
 adjustment carried out by the lower 
 centers is unusual, as when one de- 
 scends suddenly in an elevator, the 
 muscular reactions, rather than the pri- 
 mary sensory stimulation, give rise to 
 a clearly recognizable experience. The 
 observer feels an unusual tension in 
 his abdominal muscles or muscles of 
 some other part of the body. 
 
 The cochlea and sensory areas in the 
 vestibule. Turning from the semicir- 
 cular canals to the other canal leading- 
 out of the vestibule, namely the coch- 
 lea, we find here the organs which 
 are concerned in the reception of tonal 
 stimulations. It is not clearly known 
 whether noise stimulations are received 
 in the cochlea or not. The probabili- 
 ties are that noise stimulations affect 
 certain cells constituting sensory areas 
 in the wall of the vestibule. At all 
 events, it is true that there are cells 
 situated in the wall of the vestibule 
 
SENSATIONS 
 
 109 
 
 
 
 Tpangli 
 
 Scala ^^^ 
 
 vestibuli ^ 
 
 Scala tyrtipani 
 
 iiv^SJSS*-' 
 
 
 (■.-'/^•■\«l 
 
 g^Mi 
 
 which seem to be suited to the reception of simple stimuH 
 (see Fig. 29). The vestibule is the direct descendant of 
 the primitive vesicle. This fact would seem to argue in 
 favor of the view that noise stimulations, which are undif- 
 ferentiated and probably earlier than tonal stimulations, 
 affect these cells in the vestibule. Whatever may be true 
 of noise, it is certain that the tonal 
 excitations are received through the 
 complicated structures which have 
 been developed, and appear in the 
 cochlea. The cochlea is a highly 
 developed organ, richly supplied 
 with cells and fibers for the recep- 
 tion of a great number of different 
 stimulations. It consists of a double 
 spiral canal, which winds around 
 two and a half times. The winding 
 of this canal is merely an anatomi- 
 cal device for compressing the 
 whole organ into as small a space 
 as possible. The canal, which is 
 cylindrical in form, is divided into 
 three parts, — the scala vestibuli, 
 the scala tympani, and the ductus 
 cochlearis. This division can best 
 be seen by making a section across 
 the cylindrical passage. Fig. 30 
 shows such a section with the division. The scala tympani 
 is partially separated from the rest of the cochlea by a bony 
 shelf which extends for some distance into the canal. The 
 division is completed by an important membrane. This 
 membrane, known as the basilar membrane, is made up of 
 a series of fibers which differ in length as the membrane 
 passes from the lower to the upper extremity of the canal. 
 At its lower extremity the fibers are short, and at the 
 
 Fig. 30. The structure in the 
 
 cochlea as seen when a trans- 
 verse section is made across 
 the canal 
 
 The parts are clearly marked in 
 the figure. Special attention 
 should be given to the basilar 
 membrane and the organ of 
 Corti situated upon it. The 
 nerve fibers are distributed 
 among the cells of the organ 
 of Corti from the ganglion in 
 a manner similar to that repre- 
 sented for the vestibular cells in 
 Fig. 29. (After Herrick) 
 
no PSYCHOLOGY 
 
 upper end of the canal they are about twelve times as long. 
 Helmholtz, the great German physicist, called attention to 
 the striking similarity between the structure of the basilar 
 membrane and the system of strings of a musical instrument 
 capable of giving a variety of different tones. He also ad- 
 vanced the hypothesis that the fibers of the membrane are 
 so related to external tones that a given fiber is set in 
 vibration by each particular rate of vibration. It is a well- 
 known principle of physical science that any fiber or rod 
 will vibrate sympathetically with a tone which has the same 
 rate as it would assume itself, if it were set in vibration by 
 some other cause. This principle is known as the principle 
 of sympathetic resonance. The basilar membrane is so situ- 
 ated that the vibrations which enter the inner ear through 
 the fenestra ovalis reach it by passing up the scala vestibuli 
 and the ductus cochlearis. The scala tympani is a canal 
 which carries back the vibrations after they have acted on 
 the basilar membrane. It is connected at the upper end of 
 the cochlea with the scala vestibuli and serves to conduct 
 away the vibrations rather than allow them to be reflected 
 back into the vestibule ; for its lower end does not open into 
 the vestibule, but communicates through an opening, known 
 as the fenestra rotunda, with the internal meatus. The 
 basilar membrane thus stands in the direct path of the vibra- 
 tions, and it is, probably, the organ which takes up the 
 vibrations through sympathetic resonance and makes them 
 effective in exciting the sensory cells. 
 
 Sensory cells in the cochlea. A system of receiving 
 cells, analogous to the rods and cones in the eye, is placed 
 directly on the basilar membrane. At any given point they 
 form an arch extending across the membrane, and, there- 
 fore, are capable of taking up any vibration which sets the 
 fibers of the membrane in motion. The arch of cells is 
 shown in Fig. 30 and is known, from the physiologist who 
 first described it, as the organ of Corti. Among the cells 
 
SENSATIONS TIT 
 
 that constitute the organ of Corti there are distributed nerve 
 fibers which come from auditory ganghon or true sensory 
 nerve cells situated in a cavity in the bony core of the coch- 
 lea. Whenever the cells of Corti are set in vibration, they 
 excite the fibers. The external air wave is thus transformed 
 in the organ of Corti into a nervous process. 
 
 Contrast between auditory and visual processes. It is to 
 be noted that the transformation is of a distinctly different 
 type from that which takes place in the eye. In the eye 
 the physical stimulus produces a chemical activity in the 
 rods and cones. In the case of the ear the stimulus con- 
 tinues in the form of vibrations until it produces its final 
 effect upon the nerve cells. There is a less fundamental 
 change in the character of the stimulus as we pass from the 
 external world to the nervous process in the ear than there 
 is in the corresponding transition in the eye. This fact 
 shows itself most clearly when we come to deal with com- 
 pound sound vibrations. It makes no difference how many 
 tones are sounded before the tympanic membrane, the com- 
 plex vibration will be faithfully transmitted by the chain of 
 ossicles and the other accessory organs and will, at all 
 points in its transmission, be a detailed reproduction of the 
 total complex of sound impulses which gave rise to it. 
 Furthermore, it is shown by an examination of sensory 
 experience that there must be a separate sensory process 
 for each component of the tonal complex. If an observer 
 listens to a tonal complex, such as an orchestra, the sensory 
 excitations do not fuse as do the chemical processes result- 
 ing from a number of colors which act upon the retina 
 together. Each tone in the complex retains its independent 
 value for experience. It was this fact, together with the 
 form of the basilar membrane, which led Helmholtz to sug- 
 gest his hypothesis. Whether that particular hypothesis is 
 true or not, we may confidently assert that the different 
 parts of the organ of Corti are specialized in some way or 
 
112 PSYCHOLOGY 
 
 other, so that each rate of external vibration, whether it 
 reaches the cochlea alone or as part of a complex of vibra- 
 tions, excites a particular part of the sensory organ and so 
 gives rise to a distinct sensory process. The ear is thus 
 seen to be an analyzing sense capable of carrying to con- 
 sciousness at one and the same moment a vast complex of 
 sound. There is nothing in auditory sensation to corre- 
 spond to white among the retinal sensations unless it be 
 mere noise. But even here there is a fundamental differ- 
 ence, because the various elements of a noise can be heard 
 separately, especially if some of the elements have a tonal 
 character. For example, the ear has no difficulty in hearing 
 at the same time the noise produced by a train and the 
 sounds produced by the human voice. 
 
 Beats, difference tones. There are certain special cases of 
 complex air vibration which should be mentioned in this 
 discussion of sensations. If two closely related tones are 
 sounded together, they will reenforce the vibration of the 
 air particles which they affect so long as their phases are 
 alike, but the moment their phases come into such a relation 
 that one tends to set the air particle vibrating in a given 
 direction and the other tends to set the same air particle 
 vibrating in the opposite direction, they will partially counter- 
 act each other in such a way as to keep the air particle for 
 a moment in a state of equilibrium. Fig. 31 represents, 
 in the form of a water wave, two vibrations which at the 
 outset cooperate in giving a larger wave. As one lags 
 slightly behind the other, they come later to counteract each 
 other in such a way that no vibration takes place, as shown 
 at M, The result of such a combination of tones, which is 
 a purely physical affair, is that the observer receives not 
 only the two primary vibrations but also a series of rapid 
 variations in intensity, which succession of intensities fuses 
 into a new impression. The observer therefore hears, in 
 addition to the two fundamental tones, an alternate rising 
 
SENSATIONS 113 
 
 and falling in the loudness of the sound, which fluctuation 
 gives rise to experiences known as beats. If these beats 
 are slow enough to be distinguishable, they will be recog- 
 nized as quite distinct from the tones. If, on the other 
 hand, they become too numerous to be separately apprehended, 
 they may sometimes be heard as an additional tone, when 
 they are designated as difference tones. For example, if 
 two tones, c and g^ are sounded together, these tones having 
 vibrations at the rates of 256 and 384 vibrations per second, 
 the result will be a complex in which both c and g will be dis- 
 tinctly heard ; but there will also be heard a third tone, the 
 
 Fig. 31. Diagram to represent the formation of beats 
 
 The two curves represented by the light hne and the dotted Hne begin together, 
 showing the same phase at the same time. The wave motion represented by the 
 dotted Hne is somewhat more rapid than that represented by the full line ; conse- 
 quently, the relation of the~two waves changes so that in the region M the two are 
 in opposite phases. The heavy line indicates the results of the combination of the 
 two waves, a^ b, <;, d, e^ /, g^ h indicate the strong curve which results from the 
 reenforcing influence of the two wave motions. M indicates the result of the coun- 
 teracting influence of the two. (After Ebbinghaus) 
 
 number of vibrations of which equals the difference between 
 the number of vibrations of c and g. That is, the difference 
 tone in this case will be a tone of 128 vibrations per second. 
 Summation tones. Again, there are complexities in the 
 tonal experience such that often tones are heard in a tonal 
 complex which, in number of vibrations, are equal to the 
 sum of the two fundamentals. Such tones are known as 
 summation tones. They do not seem to be purely physical 
 facts, explicable in terms of the physical effect upon the air 
 particles, for they cannot, in all cases, be reenforced by physi- 
 cal resonators (the apparatus which is commonly used in the 
 detection of single tones in tonal complexes). Summation 
 
114 PSYCHOLOGY 
 
 tones seem rather to be due to certain physiological proc- 
 esses, perhaps to interferences of the vibration processes 
 in the basilar membrane or to secondary vibrations in the 
 bony walls of the cochlea. In ordinary experiences differ- 
 ence tones and summation tones play no important part, 
 but the result of these tones upon harmonies and discords 
 in music is a matter of some importance and one which 
 has been made the subject of careful examination. 
 
 Harmony not a matter of sensation. By these discussions 
 of tonal sensations and their combinations we have been 
 led to the point where it would be appropriate to take up 
 the matter of harmony. Certain tones, when sounded to- 
 gether, give the observer an experience which is not merely 
 that of tones sounding together, but is also an experience 
 of the smooth fitting together of these tones, while other 
 combinations give the observer a distinct impression of jar 
 or discord. The effort has often been made -to explain 
 harmony and discord as due to beats and like facts ; that is, 
 to certain simple processes in the organ of sense. We shall 
 dismiss the matter in a somewhat dogmatic fashion by say- 
 ing that such explanations of harmony, by processes of a 
 purely sensory type, are not satisfactory. There is probably 
 a close relation between recognition of harmony and motor 
 processes, such as those of the vocal cords and those of the 
 inner organs which, as will be seen later, are aroused during 
 emotional experiences. 
 
 Absence of after-images in auditory sensations. Before 
 closing the discussion of tonal sensations it should be noted 
 that the nature of the auditory sensory process is such that 
 contrast and after-effects do not appear to any great extent 
 in tonal or noise sensations. The process in the nerve cells 
 terminates as soon as the external vibration ceases. This 
 characteristic of sound sensations explains why it is that 
 these sensations can be used in musical compositions. A 
 succession of colors, given in anything like the same 
 
SENSATIONS 
 
 115 
 
 relation as a succession of tones in music, would produce a 
 hazy blur of after-effects. 
 
 Tone deafness. Cases of tonal deafness, or inability to 
 receive certain tones, have been described, A person capable 
 of the usual tonal discriminations in many parts of the 
 scale is quite unable to distinguish tones in a certain limited 
 part of the scale or at one end of the scale. This deficiency 
 is undoubtedly related to some lack of normal functioning 
 in a given region of the basilar membrane, or organ of 
 Corti. In old age a person may also show increasing 
 deficiency in ability to hear very high tones. 
 
 SUMMARY 
 
 Without attempting to summarize all that has been said in the 
 discussions of tonal sensations, it may be advantageous to prepare 
 a table which may be used for the purposes of comparison with 
 the earlier tables referring to visual sensations. 
 
 Physical Vibration 
 
 Series of air vibrations 
 below 10 per second 
 
 Continuous series of 
 changes in rate of 
 air vibration from 
 32 per second to 
 30,000 or 40,000 
 per second 
 
 Same as above 
 
 Complex vibrations 
 
 Complex vibrations 
 
 Physiological Process 
 
 No physiological excitation 
 
 A very large number of dif- 
 ferent processes in the 
 basilar membrane and 
 organ of Corti ; the num- 
 ber being, however, less 
 than the number of phys- 
 ical processes 
 
 More limited number of phys- 
 iological processes because 
 of incomplete development 
 of the organ of Corti 
 
 Separate physiological proc- 
 ess for each component 
 of the complex 
 
 Interference of vibration in 
 the physiological organs 
 
 Sensation 
 
 No sensation 
 
 Large number of sen- 
 sations ranging in 
 series from lowest 
 to highest pitch 
 
 Partial tone deafness 
 
 Recognizable com- 
 plex of tonal sen- 
 sations 
 
 Summation tones not 
 paralleled by objec- 
 tive vibrations 
 
ii6 
 
 PSYCHOLOGY 
 
 C, Sensations of Taste and Smell 
 
 Taste and smell differentiations of a primitive chemical 
 sense. Sensations of taste and smell may be considered 
 together. Indeed, in the primitive forms of animal life, 
 taste and smell constitute a single chemical sense. Of the 
 two the sense of smell is distinctly later in its development, 
 appearing as an important separate sense with the appearance 
 
 of the air-breathing animals. 
 
 Position of olfactory organ in 
 the nasal cavity. It is unneces- 
 sary here for us to consider at 
 any great length the nasal cavities 
 in which the olfactory cells are 
 situated. These cavities are not 
 true accessories to the organ of 
 sense, as were the cavities in the 
 ear. The organ of sense is rather 
 Fig. 32. The inner cavity of accessory to the general organ of 
 
 the nose 
 
 The arrow A indicates the path of 
 the air in ordinary respiration ; B 
 indicates the path of the air when 
 the animal sniffs. The olfactory re- 
 gion is indicated by the black area 
 in the upper part of the cavity 
 
 respiration. The position of the 
 sensory cells is such that they are 
 not in the direct path of the great 
 volume of air which is used in 
 the process of respiration. Fig. 32 
 shows the area within the nasal 
 cavity which is covered by olfactory cells. The arrow A in 
 the figure indicates the path of the air current in ordinary 
 respiration. It will be noted that in such ordinary respira- 
 tion very little of the air is carried up into the upper part 
 of the nasal cavity and thus brought into contact with the 
 sensitive cells. If for any reason it is desirable that the 
 sensitive cells should receive the full current of air which 
 enters the nose, the animal must sniff the air forcibly into 
 the nasal cavity, in which case it will follow the direction of 
 the arrow ^5 in the figure. 
 
SENSATIONS 
 
 117 
 
 WW 
 
 structure and function of the olfactory surface. The 
 
 olfactory surface itself is made up of two kinds of cells, 
 as shown in Figs. 33 and 34. There are, first, certain 
 supporting cells which line the nasal 
 cavity ; and second, there are distributed 
 among the supporting cells true sensory 
 cells, from which fibers pass inward to 
 the central nervous system. The nerve 
 cells in this organ are immediately on the 
 surface, in such a position that particles 
 brought in through the air currents come 
 into direct contact with the cell body 
 proper. This direct exposure of the nerve 
 cells to stimulation is undoubtedly related 
 to the fact that these cells are very easily 
 fatigued. It is a well-recognized fact 
 that an odor which is very striking at 
 first soon grows less and less impressive, 
 even though the stin^ulus may continue Fig. 33. Section show- 
 in its original intensity. Furthermore, ^^^ ^^^ different cells 
 
 ^ which compose the 
 
 the olfactory cells do not seem to be very mucous lining of the 
 definitely specialized, and there are no nose in the olfactory 
 
 region 
 
 By the staining process, 
 the special sensor)^ cells 
 are clearly distinguished 
 from the other cells as 
 black. In one of these 
 cells the nerve fiber will 
 be seen passing directly 
 out of the cell toward the 
 central organ 
 
 selective organs between the external 
 stimulus and the sensory organs which 
 determine the effect of the stimulus on 
 the nervous organs. There is, accord- 
 ingly, no clearly defined limit to the 
 number and variety of olfactory sensa- 
 tions. By way of contrast with the visual 
 organ, for example, there is, in the case 
 of the olfactory sense, nothing w^hich corresponds to the rods 
 or cones and operates to reduce all external stimulations to 
 a limited number of sensory processes. Consequently, the 
 number of olfactory sensations is very large, and the effort 
 to classify them is defeated by their variety. 
 
ii8 
 
 PSYCHOLOGY 
 
 Olfactory stimuli. With regard to the character of the 
 external stimuU which affect the cells of the olfactory sur- 
 face, our knowledge is somewhat hmited. Minute particles 
 probably detach themselves from external objects and are 
 carried by the air currents during inspiration into the nasal 
 cavity. These particles, or effluvia, produce a chemical effect 
 upon the olfactory cells. In general, it seems to be true 
 that those substances which are most fre- 
 quently brought into contact with the olfactory 
 surface produce the least effect, whereas new 
 and unfamiliar substances produce a strong 
 effect. The relation between the external 
 effluvia and the olfactory processes is probably 
 the outgrowth of the long evolutionary proc- 
 ess, in which the sense has developed as its 
 chief function the ability to warn animals of 
 the presence of unfamiliar substances in the 
 atmosphere. Noxious gases are, from the 
 nature of the case, relatively uncommon, and 
 the olfactory sense, in serving to warn us of 
 their presence, not only shows its adaptation 
 to the stimuli which are unusual but shows, 
 shown to be larger ^\^q ^hc sisfuificance of the whole develop- 
 
 than the true . . 
 
 sensory cell and mcnt as aimed at the preservation of the 
 
 somewhat differ- orP"ani<^m 
 ent in form ^ 
 
 Smell a rudimentary sense in man. Ani- 
 mals make much larger use of the sense of smell than do 
 human beings. They often take advantage of the presence 
 of strange effluvia in the atmosphere and react positively 
 to these odors, seeking the source of the odor, if it leads 
 them, for example, to food. It is to be said in this con- 
 nection that the human sense of smell can be much more 
 highly cultivated than is commonly the case, if attention is 
 directed to these sensations in early life. Such attention aids 
 discrimination, but does not change the organ itself. 
 
 Fig. 34. Olfac- 
 tory cells and 
 supporting cells 
 (much magni- 
 fied) 
 
 The supporting 
 cells are here 
 
SENSATIONS 
 
 119 
 
 Taste qualities and taste organs specialized. Turning from 
 smell to taste, we notice first that the qualities of taste sen- 
 sation are more easily reduced to a classified list. The quali- 
 ties most constantly recurring are bitter, sweet, sour, and 
 saline. If we add to the list al- 
 kaline and metallic, w^hich may 
 be compounds, it is possible to 
 classify all taste experiences as 
 belonging under the one or the 
 other of the six classes, or as 
 compounds of these. This re- 
 duction of all tastes to a few 
 qualities leads one to look for 
 structures in the organ of taste 
 which shall explain the reduc- 
 tion of the physical manifold 
 to a small number of sensory 
 qualities. The study of the 
 organs of taste showa that they 
 are specialized structures, prob- 
 ably of a selective character. 
 
 Organs of taste. The taste 
 organs are distributed through- 
 out the mouth and throat. They 
 appear in greatest abundance 
 on the papillae of the tongue. 
 Fig. 35 shows a magnified sec- 
 tion through the side of one of 
 the large papillae. At certain 
 points in the walls of the papilla 
 there can be distinguished groups of cells clustered in bulb- 
 shaped organs. These are known as the taste bulbs. Each 
 bulb is made up of a number of cells grouped about its wall 
 and constituting a minute pear-shaped organ (Fig. 36). 
 Among these cells in the bulb are distributed tactual nerve 
 
 Fig. 35. The depression between 
 
 the sides of two papillae on the 
 
 surface of the tongue 
 
 Liquids may pass down into this open- 
 ing. On its sides are taste bulbs. Their 
 number and distribution are indicated 
 in the figure 
 
I20 
 
 PSYCHOLOGY 
 
 fibers and special taste fibers (Fig. 37), which come from 
 nerve cells. located in the immediate vicinity of the medulla. 
 The cells of the taste bulb are chemically affected by certain 
 fluids which act upon them, and the chemical processes set 
 up within the peripheral cells are transmitted first to the nerve 
 fibers, and through these to the nerve cells, and, fimally, from 
 
 the receiving nerve cells 
 to the central nervous sys- 
 tem. Probably not all the 
 cells in the taste bulbs act 
 equally in receiving taste 
 stimulations. Some of the 
 cells in the bulbs seem to 
 be specialized for the taste 
 function, while others play 
 the part of supporting 
 cells. The peripheral or- 
 gans are not true nerve 
 cells, as were the receiv- 
 ing cells in the olfactory 
 organs ; they are interme- 
 FiG. 36. A diagrammatic section of a diatc between the scnsory 
 
 single taste bulb showing the character f^b^j-g and the OUtcr WOrld. 
 of the different cells ,-t-i • r 
 
 Iheir lunction is, un- 
 doubtedly, selective. This 
 accounts for the more 
 definite and independent, 
 character of the taste quali- 
 ties as compared with odors. The selective character of the 
 taste cells is strikingly shown by the fact that not all taste 
 bulbs receive with equal facility the various taste stimula- 
 tions. Thus, the cells in the back part of the tongue are 
 much more sensitive to stimulation from bitter substances. 
 Cells in the front part of the tongue respond more readily 
 to sweet solutions. On the sides of the tongue the areas 
 
 The cells marked n are the special sensory 
 cells. The cells marked ss are supporting 
 cells. It will be noticed that the cells consti- 
 tuting the bulb are somewhat larger than those 
 which form the general surrounding tissue 
 
SENSATIONS 
 
 121 
 
 are especially sensitive to sour and saline stimulations. To 
 be sure, the localization is not absolute, especially for sour 
 and saline, but it is very far in advance of anything found 
 in the olfactory surface. 
 
 Gustatory stimuli. The substances which act upon these 
 taste bulbs must be in liquid form. If one dries the tongue 
 thoroughly, the substances 
 which would otherwise pro- 
 duce taste impressions can 
 be pressed against the 
 tongue without producing 
 any effect. For example, 
 a piece of dry salt placed 
 upon the dry surface of 
 the tongue will not give 
 rise to any taste sensation. '^ ^ ^ 
 
 Fig. 37. A diagrammatic sketch show- 
 ing two neighboring taste bulbs 
 
 The supporting cells have been removed in 
 the two bulbs. The bulb on the right has 
 four specialized gustatory cells. The network 
 of fibers at the base of these cells shows the 
 mode of distribution of the gustatory nerve 
 fibers. In the bulb on the left and in the 
 intermediate tissue between the bulbs, the 
 terminations of the tactile nerv^e fiber are 
 shown. The tongue is thus seen to be an 
 organ of touch as well as of taste 
 
 D. Sensations of Touch 
 
 Organs of touch. The 
 group of sensations popu- 
 larly classified under the 
 sense of touch might very 
 properly have been con- 
 sidered at the beginning 
 of this chapter, for touch 
 is the human sense which 
 
 is most closely allied in character and in the structure of its 
 organs to the primitive senses of the lower animals. Indeed, 
 the surface of the body is a relatively undifferentiated mass 
 of protective and sensory cells, which are open to stimula- 
 tions of all kinds and capable of responding in some degree 
 to almost any form of external energy. The true nerve cells 
 for the sense of touch are situated in the immediate neigh- 
 borhood of the spinal cord. They are primitive bipolar cells, 
 
122 PSYCHOLOGY 
 
 as shown outside the cord in Figs. 13 and 14. The branch 
 •which passes out of one of these bipolar cells toward the 
 surface of the body is the receiving sensory fiber. When it 
 reaches the skin, it breaks up into a fine network of fibrils. 
 These fibrils are distributed among the cells of the skin. 
 The nerve fiber which travels inward from the receiving cell 
 extends into the spinal cord. Such a fiber was described 
 in the discussion of the spinal cord. It will be recalled that 
 this central fiber branches so as to extend upward and 
 downward through a large section of the spinal cord, send- 
 ing out at various levels collateral branches which transmit 
 the stimulation to the motor cells at the different levels of 
 the cord or transmit the stimulation to the higher nervous 
 centers. 
 
 Differentiation of the tactual fibers ; temperature spots. 
 The sensory fibers which pass to various parts of the surface 
 of the body seem to be differentiated in their functions to 
 some extent in spite of the uniformity of their structure. 
 For, while it is probably true that there is no region on the 
 surface of the body which is not susceptible to stimulation 
 in some degree by all forms of external energy, provided 
 the energy is strong enough, yet it is certain that there are 
 regions capable of responding easily to slight changes in 
 pressure and temperature. Indeed, there are areas which 
 show special susceptibility to pressure, and others which are 
 especially sensitive to temperature. The specialized areas are 
 usually points or, at most, limited areas. The most striking 
 demonstration of this differentiation of the skin can be se- 
 cured by taking a metallic point which has been reduced some- 
 what in temperature and passing this point slowly across the 
 skin. At intervals the point will be recognized as distinctly 
 cold, while on other parts of the skin it will be recognized 
 merely as an external pressure without temperature quality. 
 Those areas where the point is recognized as distinctly cold 
 have been designated cold spots. 
 
SENSATIONS 123 
 
 Pressure spots. A second type of specialized points on the 
 surface of the skin includes those points which are specially 
 susceptible to stimulations of pressure. If one applies a fine 
 hair to points on the skin, it will be found that there are cer- 
 tain points at which the pressure will be recognized, while 
 there are other points from which no sensation will arise. 
 Those points which respond to the slightest stimulation are 
 called pressure spots. The number of pressure spots discov- 
 ered in any special region will depend, of course, upon the 
 intensity of the pressure exerted by the hair, so that the term 
 ''pressure spot" is a relative term and depends for its exact 
 definition upon the intensity of the stimulus applied to the skin. 
 
 A part of this differentiation of sensory excitations is due 
 to the structures which surround the tactual sensory fibers, 
 but beyond this there is a demonstrated difference in the 
 receiving fibers themselves. 
 
 Other ''spots." Heat spots and pain spots can also be 
 found. The heat sp:)ts are much more diffuse and difficult 
 to locate than the cold spots, but they are analogous to the 
 cold spots in their response to changes in temperature stimu- 
 lation. Pain spots appear in certain parts of the body and 
 may, perhaps, be defined as specially sensitive pressure spots. 
 Whole areas of the body surface, as, for example, the cornea 
 of the eye, are so sensitive that any stimulation which is rec- 
 ognized at all will be recognized with the quality of pain rather 
 than that of simple pressure. There are certain reasons for 
 treating pain as distinct from pressure. Thus, when a sen- 
 sory nerve fiber has been injured and is gradually recovering 
 its functions, pain sensibility and pressure sensibility are 
 restored at different stages of the recovery. 
 
 Relativity of temperature sense ; chemical and mechanical 
 senses. One characteristic of the temperature spots is their 
 change in sensitivity when stimulated for a period of time by 
 any given temperature. For example, the hand which has 
 grown cold from a long exposure to cold air will react to water 
 
124 
 
 PSYCHOLOGY 
 
 of a moderate degree of temperature in such a way as to give 
 rise to the sensation of warmth, while the same hand, after 
 
 it has been exposed to 
 warm air, will give sen- 
 sations of cold from the 
 same water. This rela- 
 tivity, as it is called, of 
 the temperature sense is 
 due to the fact that the 
 nervous processes in- 
 volved are chemical proc- 
 esses which, when once 
 established, change the 
 
 Fig. 38 A. Tactual end organs condition of the sensory 
 
 A section of the cornea of the eye much magni- OrganS SO that the rCCCp- 
 
 fied. The small cells in the upper part of the tion of later Stimulations 
 
 figure show that the tissue is made up of a num- u i i 
 
 ber of small, compactly arranged cells. A nerve OependS UpOn DOth the 
 
 fiber is seen distributing its branches among present Stimulation and 
 
 these cells. This is a typical form of distribution , ^ . . . . _ . 
 
 of the tactual fiber, which ends freely in the the COndltlOn mduCCd by 
 
 surface of the body. (After Testute) past Stimulations. Simi- 
 
 lar facts have been noted 
 in the discussion of color 
 contrasts and olfactory 
 fatigue. There is no 
 marked relativity in the 
 case of sensory proc- 
 esses of hearing or of 
 pressure. There is a 
 basis in these differ- 
 ences with regard to rel- 
 FiG. 38 c. A Mis- ativity for a distinction 
 
 between the chemical 
 senses on the one hand, 
 including the temperature sense, the senses of smell, taste, 
 and vision, and the mechanical senses on the other hand, 
 
 Fig. 38 B. A Pa- 
 cinian corpuscle. 
 (After Testute) 
 
 senian corpuscle. 
 (After Testute) 
 
SENSATIONS 
 
 125 
 
 including those which depend upon direct excitation of the 
 nerve fibers ; namely, pressure and hearing. The chemical 
 senses show greater relativity and more striking after-effects 
 than do the mechanical senses. 
 
 Organs of touch at the periphery. The peripheral endings 
 of tactual fibers are in some cases surrounded by special struc- 
 tures ; in other cases the fibers end freely among the cells of 
 the skin. A number of typical end organs are shown in 
 Figs. 38-41. Some evidence has been accumulated to show 
 that the differentiated qualities of 
 tactual sensation are related to these 
 specialized structures. Thus, there 
 are certain organs which appear in 
 the conjunctiva where there is no 
 sensitivity for pressure, but where 
 there is sensitivity for cold. This 
 leads to the inference that they are 
 special organs for cold. Again, cer- 
 tain tactual cells seem to be espe- ^ ^ r- 1 • ^^ 
 
 — ^ Fig. 39. Iwo Golgi-Mazzoni 
 
 cially numerous in regions sensitive corpuscles of the type found 
 
 to pain. Pain, however, is the only by Ruffini in the cutaneous 
 
 type of sensation from certain other connective tissue of the tip 
 
 ^ ^ . of the human finger 
 
 regions where the fibers end freely 
 
 among the epithelial cells. The evidence is, therefore, not 
 conclusive that the end organs in the skin are specialized; 
 they may be primarily protective organs. 
 
 Muscle sensations and organic sensations. Sensations from 
 the inner organs of the body have sometimes been classified 
 under the tactual sense ; sometimes they have been regarded 
 as constituting separate classes. All the inner organs of the 
 body have sensory nerve fibers similar to the tactual fibers 
 which end in the skin. Thus, the muscles, joints, linings of 
 the organs of the thoracic, and especially of the abdominal, 
 regions are all supplied with sensory nerves. In discussing 
 the experiences received from the limbs, it is sometimes 
 
126 
 
 PSYCHOLOGY 
 
 A 
 
 convenient to distinguish under the name ''muscle sensa- 
 tions" the experiences resulting from the excitation of the 
 sensory fibers ending in the muscles. In like manner, 
 
 sensations from the abdominal organs 
 are sometimes classified as organic 
 sensations. The motives for minute 
 analysis of these sensations from the 
 inner organs are not strong, because 
 •-^ these sensations are relatively un- 
 differentiated. In the normal course 
 of life they come into experience 
 with a great mass of skin sensations, 
 and they never are intense except 
 when they are abnormal. 
 
 E. Sensation Intensities 
 
 Intensity a general characteristic. 
 
 Fig. 40. Shows the com- While it has been necessary to dis- 
 
 plex distribution of a tactual . , . . . - 
 
 nerve fiber in the immediate ^^^s sensation qualities m terms of 
 vicinity of a hair the relation of these qualities to vari- 
 
 The freely ending nerve fibers OUS OrganS of SCUSC and varioUS f OrmS 
 
 in region A directly under the ^f external energy, it is possible to 
 
 epidermis are to be compared ^-^ ^ 
 
 with the freely ending nerve treat the matter of scnsation intensi- 
 fibersshowninFig.38A. These ^j^g j^ ^ somcwhat morc general way. 
 
 fibers before their distribution • ^ 
 
 in the area ^ form a network in The relation of changCS lU the iu- 
 
 the cutis in the area B. Around teusity of obj CCtivC SOUUds tO changCS 
 
 the shaft of the hair are certain ... 
 
 glandular tissues marked G in m the intensity of sound scnsatious 
 the figure. Branches from the jg of essentially the samc type as the 
 
 general nerve trunk are distrib- i • i 1 • ♦ r 
 
 uted, as indicated at X, about relation bctwccn the intensity of pres- 
 the hair and its surrounding tis- ^^j;q stimuli and prcssurc scnsations. 
 
 sues. (After Retzius) x i i • • • i • i r 
 
 indeed, it is m this sphere or sensa- 
 tion intensities that the general methods of modern experi- 
 mental investigation were first most fully developed. The 
 early experimental investigators had the largest confidence 
 
SENSATIONS 
 
 127 
 
 that they would be able to develop general mathematical 
 formulas which would define the relations between external 
 stimuli and sensation intensity with a degree of comprehen- 
 siveness and precision comparable to that which is attained 
 in the physical sciences. As a result, they performed the most 
 laborious experiments and collected a mass of data which is 
 not equaled in quantity by the data relating to any other single 
 sphere of psychological phenomena. 
 
 Weber's Law. The general principle 
 which was established by these investiga- 
 tors is commonly known as Weber's Law. 
 This law states that the increase in sen- 
 sation intensity does not follow directly 
 the increase in the physical stimulus. 
 While the physical stimulus is increasing 
 either continuously or by additions of 
 small increments, the sensation increases 
 in recognizable intensity only after there 
 has been a certain percentage of increase 
 in the intensity of the external stimulus. 
 To make the matter concrete, if a certain 
 intensity of light is continuously increased 
 or is increased step by step by small ad- 
 ditional amounts of energy, there may 
 result in subjective experience no appreciable increase what- 
 soever. Before a change in the intensity of the sensation can 
 arise, the external light must be increased by about j^-^ of 
 its original intensity. Various investigators have found some- 
 what different fractions ranging from yig or j^j to -Jy, but 
 in any case when the fraction is determined for a given in- 
 tensity of light, say one hundred candlemeters, the same 
 fraction holds, at least approximately, for all other medium 
 intensities. The meaning of Weber's Law can be made 
 clear by considering the following negative illustration. If we 
 add to a single candle the small quantity of light necessary 
 
 Fig. 41. Tooth of 
 Gobinus showing dis- 
 tribution of nerve 
 fiber throughout the 
 canal of the tooth. 
 (After Retzius) 
 
128 PSYCHOLOGY 
 
 to Increase it by j^-^^ an observer will be able to recognize 
 the change. If, now, we add to a light of one thousand 
 candlepowers the same ^-l--^ of a single candlepower, the 
 effect will be absolutely unappreciable ; that is, the sensation 
 in consciousness will not be modified at all. Ten candle- 
 powers must be added to one thoii's'S.iid^feefore an appreciable 
 change takes place in the observer's experience. 
 
 General statement of the law. The law holds in general 
 for all spheres of sensation intensity. The ratio of increase 
 in the different spheres of sensation differs. Thus, while 
 it is j^-^ for light, it is given by Wundt as -^^-^ for pressure. 
 Other fractions are reported for other spheres of sensation. 
 In general, however, the relation is always of the same type. 
 It has been expressed briefly in the statement, if the sen- 
 sation is to increase in an arithmetical ratio, the stimulus 
 must increase in a geometrical ratio. The range of applica- 
 bility of this general principle is limited in each case to 
 stimuli of moderate intensities. 
 
 Mechanical explanation of Weber's Law. After the law 
 has been established as a statement of an empirical fact, it 
 is by no means easy to determine its value for the explana- 
 tion of mental life. It probably expresses a law of nervous 
 behavior which is a special case under the general mechanical 
 principle, that any increase in any form of physical activity 
 becomes more and more difficult as this activity reaches a 
 higher level of intensity. For example, it is extremely 
 difficult to add to the speed of a locomotive beyond a certain 
 point. If the locomotive is moving at the rate of fifteen 
 miles an hour, a moderate increase in the amount of energy 
 applied to the machinery will increase the speed by a mile 
 an hour. If, however, the engine is moving at the rate of 
 sixty miles an hour, the amount of energy which must be 
 expended to add one mile to its speed is very much greater 
 than the amount which was necessary to add this same in- 
 crement of speed when the engine was moving at the rate 
 
SENSATIONS 129 
 
 of fifteen miles. This mechanical principle is applicable to 
 the action of the nervous system. If the external stimulus 
 acting upon the sense organs is producing a certain mod- 
 erate degree of chemical activity, that chemical activity can 
 be intensified by a small addition to the external stimulus. 
 If, however, the stimulus acting upon the nerve cells is so 
 strong that it demands nearly all of the energy that the cell 
 is capable of giving out, then the small addition to the 
 stimulus will produce no effect. Since this is a general 
 principle of all nervous behavior, it is a principle which 
 appears alike in all the different spheres of sensation. 
 
 Other views regarding Weber's Law. Other interpreta- 
 tions of Weber's Law have been given in the history of 
 psychology. One such interpretation, given by Fechner, 
 was of a most ambitious type and was intended by its author 
 to express in exact mathematical terms the general relation 
 between mind and matter. The significant fact which 
 Fechner was emphasizing, that the relation between con- 
 sciousness and the physical world is not direct, is abundantly 
 established by considerations of a more general character 
 than those which Fechner took up. We have seen in our 
 earlier discussions of sensation qualities that there are many 
 other phases of experience which do not parallel the physical 
 facts with which they are related. The importance of Weber's 
 Law as a demonstration of the indirectness of the relation 
 in question is, therefore, relatively less now than it was in 
 the time of Fechner, and his definite mathematical formulas 
 are of no value. The whole study of sensation intensities 
 was, indeed, more productive for general psychology in the 
 experimental methods which it served to cultivate than in 
 the contribution which it made to the content of psychology. 
 The discussion of sensation intensities may, accordingly, be 
 dismissed without further detail. 
 
CHAPTER VI 
 
 EXPERIENCE AND BEHAVIOR 
 
 All consciousness complex and selective. A man comes 
 into a room and sees a piece of paper on the table. He 
 walks to the table, picks up the paper, and after looking at 
 it throws it down again. If we try to give a psychological 
 explanation of these acts, we find ourselves adopting some 
 such formula as this. The act of going to the table and 
 picking up the paper is due to curiosity and an inner desire. 
 Curiosity and desire are aroused by the sensory impression 
 which the paper made on the man's eye. After the first 
 act of picking up the paper, a new series of visual im- 
 pressions fell on the retina ; these new impressions aroused 
 a new series of inner processes and the act of throwing 
 down the paper followed. Experience is thought of under 
 this formula as a series of cycles, each beginning in a sen- 
 sation and ending in an act. 
 
 The formula is much too simple. When we consider 
 carefully the first statement '' sees a piece of paper," we find 
 at once that we are dealing not with a sense impression 
 alone ; we are dealing with a vigorous form of behavior. 
 The act of looking at an object involves the turning of the 
 two eyes in a very complicated way on the object and in- 
 volves also the focusing of the lenses inside the eyes. Not 
 only so, but looking at an object is a highly selective per- 
 ^formance. The room into which the man came offered to 
 his vision a hundred shades of color and a hundred varieties 
 of brightness. Out of all these he fastened on one small 
 patcho The walls of the room were quite as bright as the 
 
 130 
 
EXPERIENCE AND BEHAVIOR 131 
 
 paper and very much more extensive ; they offered sensa- 
 tions which in their quahty and intensity would overwhelm 
 the piece of paper if sense impressions alone determined 
 the flow of mental life. The fact that the man looked 
 at the paper rather than at the walls is the first and most 
 essential fact which the psychologist must take into account 
 if he would give an adequate explanation of the later act of 
 picking up the paper. 
 
 The selective character of conscious processes related to 
 sensory impressions. Our common descriptions emphasize 
 the active character of the processes of recognition here 
 under discussion. We say the man is interested in pieces 
 of paper, while he has no special interest in walls. Or we 
 say that the man is trained to give attention to what is on 
 the table, but is indifferent to the walls of the room. Some- 
 times we go further and give the explanation of the man's 
 interests and his attention by saying that he has cultivated 
 certain associations or certain modes of thinking which 
 determine the directions in which his mind turns. 
 
 Such statements make it clear that psychology cannot rest 
 content with the explanation that each cycle of experience 
 begins with a sensory impression. By the time the mind 
 receives a sensory impression the selective process has gone 
 a long way ; the selective process which is involved in at- 
 tending to a sense impression is itself a preliminary stage 
 of no small importance. 
 
 It will not be amiss to recall at this point one of the 
 important lessons drawn from our study of the evolution of 
 the organs of sense. Our organs of sense are by their very 
 structure selective organs. The eye cannot respond to rays 
 of light below the red or beyond the violet. The ear does 
 not record sounds of the slowest rates of' vibration or those 
 of the highest pitch. Evidently the organism has been 
 determined in its evolution by causes which are more funda- 
 mental than those of mere sensation, for there has been no 
 
132 PSYCHOLOGY 
 
 evolution of universal sense organs, but only evolution of 
 organs capable of receiving certain impressions which the 
 organism can use in promoting its own life. 
 
 Selective consciousness related to behavior. The key to 
 this whole matter is found in a study of bodily activities. 
 Every animal is a reacting being. All its functions relate 
 to what it can do. For example, there is a certain range of 
 objects which are of such size that they can be picked up 
 by the human hand or moved by human fingers. It is an 
 impressive fact of biology that the range of human vision 
 corresponds to this range of action. We do not have micro- 
 scopic eyes like the fly. Nor, on the other hand, do we 
 have distance vision like the eagle's. With our present 
 organs of behavior we could not react to the minute objects 
 which the fly sees, nor could we use far-sighted eyes to ad- 
 vantage from our position near the ground, for even if we 
 could see at great distances, we could not move fast enough 
 to take advantage of our superior sight. The range of human 
 vision has been determined by the range of possible human 
 reactions. The impressions of the eye are of importance 
 only when there is a corresponding power of action. 
 
 Common interests and their relation to behavior. That 
 action is a determining consideration in mental life will be 
 clearly seen when one begins to look at ordinary experience 
 with a view to finding what is back of sensations. One who 
 is not interested in doing something with trees will pass 
 them a thousand times and never really see them. The 
 maple tree has a shape wholly different from that of the 
 elm. The barks of the two are quite different. The casual 
 observer passes these trees day after day and his retina 
 receives the appropriate sensory impressions with their vary- 
 ing characteristics, but the impressions go to waste. Let 
 this observer be induced to try to draw the trees, and his 
 experiences undergo a vast change. The impressions begin 
 to be vivid ; they have not undergone any modification in 
 
EXPERIENCE AND BEHAVIOR 133 
 
 their character as sensory excitations, but they have taken 
 on new importance in the psychological world. The psycho- 
 logical character of the impression can be described only 
 by saying that the impression has been selected for attention 
 or has been made vivid and distinct by virtue of the effort 
 to use it. 
 
 Another example is found in the familiar experience of 
 not hearing a clock tick so long as one is absorbed in read- 
 ing. When the reading is over and there are no dominating 
 ideas in the mind, the ticking begins to be heard. The fact 
 is, of course, that the ear recorded the ticking in both cases. 
 While one was reading, the nervous system was pouring its 
 energy into the eyes which were looking along the printed 
 lines. There was, furthermore, the general muscular reaction 
 characteristic of purely visual attention, the tense breathless 
 interest in the story on the printed page. The auditory im- 
 pressions were absorbed into this stream of active processes 
 and were lost. When the activity of reading is over and the 
 body and the nervous system fall back into the miscellaneous 
 activities characteristic of partial relaxation, there may be a 
 turning of the head to listen and then the ticking may 
 occupy the center of attention. 
 
 One might multiply examples indefinitely. On the street 
 we pay little or no attention to the people whom we are 
 passing. Our one purpose in most cases is to avoid collision, 
 and our attention to sensory experience is just enough to 
 serve this end. The skilled cabinetmaker sees in a piece 
 of furniture elements which the untrained layman would not 
 notice. The hunter observes what the stranger in the woods 
 overlooks. Everywhere it is behavior that determines the 
 emphasis on sensory impressions. 
 
 Study of evolution of organs of action as important as 
 study of senses. The relation of bodily activity to mental 
 processes will be more fully understood if we trace the evo- 
 lution of the muscular system and its operations much as we 
 
 \ 
 
134 PSYCHOLOGY 
 
 traced the evolution of the organs of sense. In an earlier 
 chapter the primitive muscle cells in the body wall of the 
 hydra were shown in Fig. 4, and the contrast in both form 
 and function between the muscle cells and the neural cells 
 was pointed out. The muscle cell is large and elongated. 
 It is large so that it can store up more energy than could 
 be stored in a small cell, and its elongated form favors con- 
 traction. Fig. 42 shows a single muscle cell of one of the 
 higher animals. A muscle is made up of a mass of such 
 cells. Every muscle is supplied with a nerve the ends of 
 which are distributed to the cells and produce contractions 
 of the muscle by discharging motor impulses into the cells. 
 The phenomena of contraction are illustrated in Fig. 43. 
 This process of contraction consists in an inner chemical 
 change which uses up a part of the energy stored up in the 
 
 cell body. The proc- 
 esses may be com- 
 -r^ A 1-- 1-1 J 1 J in pared to combustion. 
 
 Fig. 42. A highly developed muscle cell ^ 
 
 When a piece of 
 wood burns, it gives off a part of the energy stored up in 
 its complex chemical substances. So it is with the muscles ; 
 they give out energy and have left behind certain waste 
 products which may be described as the ash of combustion. 
 Evolution from gross muscles to highly differentiated 
 muscles. The highly specialized muscle cells of the type 
 shown in Fig. 42 have been evolved from the cells which 
 make up the surface of the body in such simple animals as 
 the hydra. Furthermore, the muscles of the higher animals 
 have in the course of evolution become differentiated into a 
 large number of highly specialized groups of muscle cells. A 
 single illustration will make clear the type of evolution which 
 has gone on in all parts of the body. The mouth of one of 
 the lower animals, such as a fish, is opened and closed by 
 very s- nple muscles. In the higher animal forms the differ- 
 entiation of muscles goes much further. The opening and 
 
EXPERIENCE AND BEHAVIOR 
 
 135 
 
 shutting of the human mouth, for example, is not a single 
 gross performance as in the fish. The muscles of the lips 
 have been evolved and so highly differentiated that one side 
 of the mouth can be moved, as it is in many forms of facial 
 expression, quite independently of the gross opening and 
 closing of the jaw, which is the only form of movement of 
 which the fish is capable. 
 
 In like manner the 
 hand exhibits a high 
 differentiation of the 
 muscles. When we 
 study the ability of a 
 human being to move 
 one finger apart from 
 the rest of the hand, 
 we realize how far dif- 
 ferentiation of the mus- 
 cles has gone. 
 
 Behavior dependent 
 on nervous control. The 
 highly differentiated 
 muscular system of the 
 human body takes on a 
 greater significance for 
 the student of psychol- 
 ogy when it is kept in 
 mind that the muscles 
 are always connected 
 with the nervous system and are absolutely dependent on 
 the nervous system for the impulses which cause their con- 
 traction. In the lowest animal forms the muscle cells had a 
 general irritability, but in the process of evolution the muscle 
 cells have been specialized to store up great quantities of 
 energy. They do not in their later specialized stage receive 
 impressions directly from the outer world. They contract 
 
 Fig. 43. The contracted and relaxed state 
 of a muscle 
 
 The dotted lines within the muscle show the 
 distribution of the nerve fiber 
 
136 PSYCHOLOGY 
 
 only when they are excited by nervous impulses. The higher 
 the animal, the more its muscles have becomxC dependent on 
 the nervous system. The result is that when the muscular 
 system becomes highly differentiated there must be a parallel 
 evolution of the nervous centers related to these muscles. 
 There has been, accordingly, a steady evolution of the con- 
 trolling nervous organs. When we study the human hand 
 and its complex possibilities of adjustment or when we 
 study the delicate movements of the human face, we must 
 always have in mind the fact that there are corresponding 
 differentiations of the nervous system. 
 
 Coordination as necessary counterpart of differentiation. 
 There is another consequence of this differentiation of 
 the motor organs which is of importance for our study. 
 The highly differentiated muscles may, indeed, contract 
 each by itself in the performance of some special function 
 for which it was evolved, but for the most part^the special 
 muscles act in systems. The individual muscle becomes 
 for the purpose of the moment not a separate organ, but 
 a part of a system of cooperating muscles. For example, 
 the single finger may move by itself, but in many of the 
 activities of life the single finger contributes its strength 
 to a grasping movement which enlists all the other fingers 
 and the whole hand. In a grasping movement the finger is 
 not a separate organ. Here, then, we have a complex situ- 
 ation ; the differentiated muscles which move the finger 
 must sometimes act separately, sometimes as parts of a 
 combination of many muscles. In the same way the 
 nervous centers must be both specialized and capable of 
 entering into combination. 
 
 Individual development in behavior. The history of indi- 
 vidual development of muscular control shows how conipli- 
 cated is this matter of muscular action. There is a natural 
 tendency on the part of the infant to contract certain of the 
 muscles of the body in a primitive gross combination. Thus, 
 
EXPERIENCE AND BEHAVIOR 137 
 
 the infant can close the hand on any small object like a 
 pencil which is laid across the palm. The fingers all enter 
 into this act, and the muscular system of the hand and arm 
 cooperate in a single performance. This primitive act is 
 very like that exhibited by the animals lower in the scale 
 than man. In the course of later life the child will have to 
 .acquire by practice the ability to move his individual fingers 
 without including the others. Thus, if he learns to play on 
 the piano, he must not move all the fingers together. In 
 such a case he must learn to differentiate the fingers from 
 each other. 
 
 Conversely, there arises even in infant life the necessity 
 of developing a careful cooperation between the different 
 parts of the body. The two hands must work together in 
 grasping an object. The head and eyes must turn toward 
 an object which the hand is to grasp. Later in life the 
 fingers which have become skilled in striking the piano 
 keys separately must cooperate in striking the chord. 
 
 In these examples the body is seen to be a highly evolved 
 system of reacting organs constantly developing, on the one 
 hand, in the direction of finer and more delicately adjusted 
 movements and, on the other hand, in the direction of 
 more complex combinations of these differentiated forms 
 of behavior. 
 
 In terms of our description we may distinguish three 
 stages of muscular activity, always recalling that there are 
 corresponding stages in the development of processes in 
 the nervous system. First, there are gross adjustments ; 
 second, differentiated forms of movement ; and third, coor- 
 dinated forms of action. The term '' coordination " here 
 introduced will recur frequently in later discussions. Its 
 meaning will be clear from the foregoing discussions. A 
 coordinated movement is one in which groups of differen- 
 tiated muscles cooperate under the control of nerve centers, 
 thus producing complex but completely unified acts. 
 
138 PSYCHOLOGY 
 
 Inherited coordinations or instincts. There is one impor- 
 tant fact of heredity which must be included in the pre- 
 liminary discussion of bodily movement before we are in a 
 position to understand fully the relation of behavior to con- 
 sciousness. The higher animals come into the world with 
 many coordinated forms of behavior fully provided for in 
 the inherited structure of their nervous systems. For ex- 
 ample, a human infant is able at the beginning of life to 
 use the lips and tongue in the complex act of sucking and 
 he is able also to swallow through the cooperation of the 
 muscles of the throat. Such an inherited complex of coor- 
 dinated acts is called an instinct. The nervous centers in 
 control of the lips and tongue are evidently coupled by 
 lines of connection which the long experience of the race 
 has laid down, and the infant is equipped from the first 
 not only with differentiated muscles and controlling centers 
 but with a fully developed organization in his nervous system 
 which results in the cooperation of the differentiated centers. 
 
 Glands as active organs. To this discussion of the devel- 
 opment of the muscles and their contraction should be adde(5 
 the comment that there is another group of active organs ; 
 namely, the glands. These secrete under the stimulus of 
 the nervous system, and their behavior can for purposes of 
 our discussion be regarded as like that of the muscles. 
 
 A constant tension of active organs as background of all 
 behavior. In order to understand the relation of the be- 
 havior of the muscles and glands to consciousness, one 
 general fact which is very commonly overlooked must be 
 kept clearly in view. The active organs of the body are 
 at all times during life in a state of tension. There are 
 constantly pouring out of the nervous system streams of 
 motor excitations. These are distributed to different parts 
 of the body in currents of varying intensity, but there 
 is always a stream of motor impulses going to the active 
 organs. 
 
EXPERIENCE AND BEHAVIOR 139 
 
 One reason why this fact is not clearly recognized is that 
 we ordinarily think of the nervous system as in action only 
 when some part of the body is actually moving. Thus, if 
 the hand moves from near the body to a distant point in 
 order to pick up some object, we realize that the muscles 
 of the arm are contracting. But if the individual sits 
 rigidly in his seat, resisting the impulse to reach for the 
 object, we overlook the fact that his muscles are on the 
 stretch, often to an extent involving much greater effort 
 than would be required to grasp the object. 
 
 Evidences without end could be adduced to show that 
 the muscles are in constant action. The neck muscles 
 are constantly in action holding up the head of a waking 
 man. Let the neck muscles relax for a moment, as they 
 do when the man begins to get drowsy, and gravity will 
 pull the head forward, giving a striking exhibition of the 
 work which the neck muscles are doing most of the time. 
 
 Again, consider what happens at all times by way of brac- 
 ing the body for mm^ements. The trunk muscles tighten 
 when the hand begins to reach out because the trunk must 
 balance the new weight which is taken up in the hand. 
 
 Not alone the trunk muscles but the whole inner mech- 
 anism of the body is drawn into action even by the most 
 trivial movement. The blood circulation accommodates it- 
 self to every act. This means that the contraction of an 
 arm muscle calls for more blood to the arm. The call 
 affects the heartbeat and the contraction of the muscles 
 in the arteries which control the pressure of the blood in 
 all parts of the body. The adjustment of blood circulation 
 affects respiration and digestion and the inner glandular 
 action, until finally the whole body is involved in the effort 
 to move the arm. 
 
 Meaning of sensory impressions dependent upon inner 
 conditions. We are now in a position to understand the facts 
 which were taken up in the early paragraphs of this chapter. 
 
I40 PSYCHOLOGY 
 
 A sensory impression does not come into a nervous system 
 that is in suspense waiting to be aroused to action. A sen- 
 sory impression is not the first or primary step in a series 
 of nervous processes. The sensory impression comes into 
 an inner world full of action. The new impression may 
 change the mode of action or it may be absorbed into the 
 processes under way. Again, using another figure, we may 
 say that the inner world is constantly weaving its material 
 into a pattern. The new sensory impression is new raw 
 material. It may be necessary to shut down the machinery 
 and recast the pattern in order to deal with this new mate- 
 rial. Ordinarily it is not necessary to shut down. Ordinarily 
 the new raw material is perfectly familiar and with very little 
 disturbance of the routine is absorbed into the existing pat- 
 tern, and the machinery goes on as it was working. 
 
 Other analogies could be drawn on to help in describing 
 the situation ; the best are always those which are closest to 
 mental life itself. Thus a social group receives a newcomer. 
 The arrival is not the beginning of the group's social activ- 
 ity. The arrival may make no striking impression on the 
 conversation. On the other hand, the new arrival may turn 
 all currents of thought and social life into new channels. 
 The new social situation in any case will be the result of 
 what was, plus the modifying influence of what now is. 
 
 Sensory processes and the equilibrium of action. So it is 
 in the action of the nervous system. Before a particular 
 sensory impression comes, the nervous system is in a state of 
 general excitation. Continuous streams of incoming sensory 
 impulses and streams of outgoing motor processes constitute 
 a complex of nervous life. The character of this complex is 
 determined primarily by those inner paths of combination 
 which have been developed in the organism's history and 
 in its past struggles with the world. Into this inner world 
 with its stresses and strains comes a new sensory impulse. 
 In the great majority of cases the new impulse does not 
 
EXPERIENCE AND BEHAVIOR 141 
 
 work any radical effect. The central processes are under 
 way and they go on as before, absorbing into their main 
 current the little stream of new sensory energy. Every now 
 and then the new impulse is so strong or it fits into the 
 workings of the central nervous system with such a power 
 to change the equilibrium of action that a radical change 
 takes place. One is reading and hears his name called 
 from the next room. The name arouses action because it is 
 imperative in its command over one's action. The call need 
 not be strong, but it is one of the keys to a vigorous form 
 of behavior entirely opposed to reading. In such a case the 
 action is abruptly changed in its direction of operation. 
 
 Importance of sensations dependent on organization. Even 
 when one of the abrupt and impressive changes in central 
 nervous action comes, it is not the sensory impulse as such 
 which explains the change. The ability of the individual to 
 react is here the chief consideration. An impression can 
 never be strong unless the organization of the individual is 
 prepared to receive it. Indeed, as pointed out earlier in the 
 chapter, the whole evolution of the animal world indicates 
 that the sense organs themselves evolve in the direction 
 dictated by the demands for action. 
 
 Sensations unduly emphasized through introspection. The 
 discussion of activity as taken up thus far in this chapter 
 has made very few appeals to the reader's conscious analysis 
 of his own experiences. The reason is that the view of con- 
 sciousness here presented is not the one suggested by intro- 
 spection. Introspection tends to bring into overemphatic 
 relief new sensory impressions. It is not difficult to note 
 what goes on in consciousness when a color is seen or a 
 sound is heard, for the points in consciousness where a color 
 or a sound becomes vivid are relatively easy to distinguish 
 from the m.ain current of mental life. Consciousness pauses 
 for a moment and gives emphasis to the arrival of the new- 
 comer. It is much more difficult to look at the main current 
 
142 PSYCHOLOGY 
 
 of experience because a person is in the midst of the cur- 
 rent, absorbed in its movement and thus without any con- 
 trasts by means of which to make himself vividly aware of 
 that which fills his whole mind. Just as the social group 
 which was referred to a few paragraphs back is not aware 
 of its own atmosphere and of its own appearance but is 
 clearly conscious of the new member, so personal conscious- 
 ness must adopt new scientific methods of recognizing its 
 own characteristics. 
 
 Attitudes. Perhaps the use of a special term will help in 
 bringing out what is here being emphasized. There is in 
 every mental act an aspect which comes from the individual's 
 reactions on his impressions. We may call this aspect of 
 experience an attitude. Thus there are attitudes of liking 
 and disliking. If the attitude is vivid, one may readily ana- 
 lyze it out of the complex and say, '' I like the color or the 
 sound or the taste," or '' I dislike the impression." If the 
 attitude is not so vivid or so distinctive in character, it may 
 be more difficult to separate it for purpose of study from 
 the impression. A color may receive the attention of an 
 observer, thus arousing a very definite and positive attitude 
 called attention, but it is difficult to describe what one 
 means by the word '' attention." It is also difficult to dis- 
 entangle attention from the color experience itself. Yet a 
 moment's scientific consideration of the matter will make 
 it quite evident that the conditions of attention are to be 
 found in the individual's organization and active processes. 
 No sensory impression carries in itself the qualities which 
 command attention. Attention is a contribution of the inner 
 world ; it is an attitude of the individual. 
 
 Attitudes not related to sensations but to behavior. Our 
 attitudes are as manifold as our modes of response to im- 
 pressions and ideas. In the next chapter we shall select for 
 treatment some of the chief attitudes of ordinary life. In 
 the meantime, it is the purpose of this chapter to reiterate 
 
EXPERIENCE AND BEHAVIOR 
 
 143 
 
 the fact that all attitudes are phases of behavior. The psy- 
 chology of the individual must study modes of behavior 
 quite as much as sensations. Indeed, if one is to be empha- 
 sized more than the other, it is the business of science to 
 bring out the significance of behavior, since this is likely to 
 be overlooked by the superficial observer. 
 
 SUMMARY 
 
 Relation of sensation to reaction. It may be well to summarize 
 the conclusions reached up to this point by means of a diagram. 
 
 
 ^M . 
 
 
 m 
 
 
 
 n 
 
 1 
 
 
 P 
 
 2 
 
 
 
 iS"--^ 
 
 r 
 
 3 
 
 
 
 Q 
 
 4 
 
 
 
 
 5 
 
 t 
 
 6 
 
 1 u 
 
 7 
 
 
 V 
 
 8 
 
 - 
 
 
 9 
 
 
 Object 
 
 
 Individual 
 Fig. 44. Diagram showing relation of sensory impressions to reactions 
 
 Let the rectangle at the left of Fig. 44 represent some object 
 in the physical world — a book or a piece of machinery. The ob- 
 ject has many physical characteristics which are represented by the 
 subdivisions i to 9. Some of these impress a human being ; others 
 do not. For example, the machine may send out waves of electric 
 energy for which we have no organ of sense ; the book may send 
 out ultraviolet rays of light which lie beyond the range of vision. 
 Subdivision 7 represents the power of emitting electric energy ; 
 subdivision 8, the power of giving out ultraviolet rays. When 
 energy from 7 and 8 reaches the surface of the human body there 
 is no organ for the reception of the stimulation. Subdivision i, on 
 
144 PSYCHOLOGY 
 
 the other hand, represents the power to reflect red light, and 
 subdivision 2 represents solidity or resistance to touch. These do 
 impress the human body if they strike the right points, as indicated 
 by the dotted lines continuing lines i a and 2 . Line i b represents 
 a ray of light which does not strike the eye, but strikes some part 
 of the skin and produces no effect. 
 
 Let us follow the dotted lines which represent currents of sen- 
 sory excitation entering the central nervous system from the eye 
 and finger. It is not usual for the central nervous system to receive 
 only two sensory impressions at any given moment, but for the 
 sake of simplicity the others are omitted. 
 
 As soon as these sensory processes enter the central nervous 
 system they begin to flow toward the muscles which constitute the 
 second surface of the body represented by the right-hand boundary 
 of the rectangle standing for the individual. In the muscular sys- 
 tem there are certain contractions — m^ //,/, r, s^ /, u^ and v^ which 
 are the results of motor impulses flowing out from the nervous 
 system. 
 
 In the central nervous system the two incoming currents are 
 brought together by the organized paths in this system. They then 
 pass through the motor centers and are distributed in such a way 
 as to reenforce s ; that is, one of the muscular tensions which was 
 present from the first. 
 
 We commonly say that the sensory impressions caused the 
 reaction s. What really happened is that certain attributes of the 
 object aroused the sensory impulses which in turn were fused by 
 the individual's inner nervous organization in such a way that the 
 reaction s of which the individual was all along capable was brought 
 into emphatic play. 
 
 Consciousness does not reflect merely the entrance of sensory 
 impressions into the nervous system ; if it did, vision and touch 
 from the same object would remain as unrelated facts in expe- 
 rience. Consciousness includes the incoming impressions, but em- 
 phasizes the fact that they are combined on- the way to a common 
 center of motor discharge. Consciousness is related to the central 
 organization and thus to the reactions of the individual quite as 
 much as to the incoming sensory impressions. 
 
 We find ourselves, accordingly, in harmony with the conclusion 
 to which our general study of the nervous system led us. We . 
 
EXPERIENCE AND BEHAVIOR 145 
 
 found, it will be remembered, that the indirect centers of the cere- 
 brum — that is, the organizing areas of the brain — are the parts of 
 greatest importance to the student of conscious life. We now see 
 that this means that the fusion of sensory impressions on the way 
 to their discharge as motor processes is the physical fact most 
 closely related to consciousness. Consciousness does not depend 
 primarily on the character of sensory impressions or of muscular 
 contractions, but is determined largely by the organizing processes 
 which follow the reception of sense impressions and their discharge 
 into motor channels. 
 
CHAPTER VII 
 
 CERTAIN FUNDAMENTAL ATTITUDES 
 
 Reactions toward objects and reactions away from objects. 
 
 If we consider the simplest forms of animal behavior, we 
 find that they divide into two classes ; there are, on the one 
 side, activities in which the animal seeks those ends which 
 gratify, such as food, warmth, and contact with its own 
 kind ; and there are, on the other side, activities in which 
 the animal seeks to escape from harm. The simplest 
 animal forms show these two types of behavior, as has 
 been pointed out in an earlier chapter (Fig. 2, and p. 16). 
 The human infant shows the same fundamental forms of 
 behavior. 
 
 Pleasure and displeasure. There are in conscious life 
 fundamental attitudes corresponding to these two types of 
 behavior. We like what we seek, and our attitude toward 
 impressions arousing this type of reaction is described by 
 the • common word ''pleasure." What we try to avoid 
 arouses within us the opposite attitude, or one of dis- 
 pleasure. In popular language the antithesis commonly ex- 
 pressed is between pleasure and pain. Pain is, in reality, 
 a very intense form of tactual sensation which comes from 
 the injury of bodily tissues. Such sensations stir up the 
 most violent efforts on the part of the organism to throw 
 off the offending object ; hence the common failure to dis- 
 tinguish between the sensory part of the experience and the 
 attitude of displeasure. 
 
 Pleasure and displeasure appear in a great variety of 
 particular forms. Thus, when the body is taking in food, 
 
 146 
 
CERTAIN FUNDAMENTAL ATTITUDES 147 
 
 there is a series 'of activities which are among the most 
 gratifying that the individual can experience. The nervous 
 system is prepared to respond positively to the stream of 
 sensory stimulations which come to the organs of taste and 
 smell from objects suited to the organism. The organism 
 is coordinated in its internal behavior to receive the objects 
 that gratify, and the nervous activity accompanying the 
 whole process is of the most favorable type. Again, the 
 comfort of sitting in a warm, bright room is different from 
 that of taking food ; but here, as in taking food, all the 
 body's reactions are harmonious and favorable, and in a 
 general way the attitude of the individual is of the same 
 quality as that which appears in the act of taking food. 
 
 Displeasure exhibits in like manner different forms. The 
 odor of some object may be disgusting because it throws 
 the body into violent activities aimed at rejection. In the 
 same general way, one tries to get away from a glaring 
 light. In both cases the action is one of self-protection, 
 and the mental attitude is one of displeasure. 
 
 There are negative conditions as well as positive which 
 produce the typical attitudes of pleasure and displeasure. 
 Thus the organism which is deprived of food or of warmth 
 will make strenuous efforts to correct the deficiency, and 
 the attitude which accompanies these efforts may be of the 
 most intense displeasure. In like manner the relief which 
 comes with the escape from impending danger may give 
 the highest satisfaction. 
 
 Cultivated feelings. In general, it may be said that what- 
 ever impression promotes the normal reaction of the organ- 
 ism is accompanied by pleasure ; whatever defeats normal 
 behavior or arouses protective recoil is unpleasant. 
 
 The history of psychology is full of efforts to classify 
 pleasures and displeasures and to show the exact relations 
 of these phases of experience to sensations. The difficulty 
 in reaching any final classification is that with the progress 
 
148 PSYCHOLOGY 
 
 of individual development new types of pleasure and dis- 
 pleasure arise just in the degree in which one learns to seek 
 or reject objects. Each human being starts with an instinc- 
 tive tendency to seek certain ends and reject others. To 
 these fundamental likes and dislikes he adds others con- 
 nected with his mature experience. Thus each of us sets 
 up certain property rights. One likes to have at hand, sub- 
 ject to his instant command, certain conveniences. If one 
 cannot find his pen or his tennis racket, he is sometimes 
 thrown into a state of distress hardly less violent than that 
 exhibited by the infant who cannot find food. The tastes for 
 pens and tennis rackets are acquired by the use of these 
 instruments, they are in no sense of the word instinctive ; 
 but once the habits of use are organized they demand the 
 opportunity for expression, and satisfaction or its opposite 
 will attach to their presence or absence. 
 
 Fear as a typical emotion. One of the significant exam- 
 ples of a strong negative attitude appears in the experience 
 which we call fear. We sometimes speak of the instinct of 
 fear. There is, indeed, in every animal a strong tendency 
 to run away from everything that is strange or large or 
 overstimulating. So delicately is the nervous system poised 
 to protect the individual that when a strange or violent 
 stimulation comes to the organs of sense there follows an 
 overstimulation of all the active organs. This overstimula- 
 tion is accompanied by an inner state of agitation. The 
 inner agitation confuses all thought and is a source of 
 displeasure just because the inner chaos is ineffective and 
 incapable of arousing any coordinated forms of expression. 
 The frightened man is proverbially not intelligent. The fact 
 is that the frightened man is internally in a commotion, and 
 his mind is blurred because he cannot cope with the situa- 
 tion. His motor processes are stalled or incoordinated, and 
 his attitude is disagreeable and increasingly so the longer 
 his inability to deal with the situation continues. 
 
CERTAIN FUNDAMENTAL ATTITUDES 149 
 
 Fear is a form of displeasure, but unique as contrasted 
 with the displeasure of rejecting an unacceptable taste or 
 color. Yet so general in character is fear that it may attach 
 to any violent form of excitement. Fear, which has been 
 described as the most primitive form of human displeasure, 
 does not disappear with modern life, but tends, rather, to 
 become more general and more intense. To be sure, it 
 attaches to new objects as man overcomes his first enemies, 
 but it is one of the most common attitudes of life. Primi- 
 tive man was afraid of an eclipse ; modern man is not. 
 Modern man is, however, thrown into a panic by an earth- 
 quake because it runs counter to all his established forms 
 of behavior to have the solid earth under his feet begin to 
 rock. The earth has been the base of all behavior, and 
 one is at a loss to control behavior when this base of action 
 changes. Not only so, but modern life contains new terrors 
 which were not known in earlier stages of civilization. The 
 embarrassment of appearing in public is one of the new 
 inventions of civilization. That there is much superfluous 
 excitement in this case is realized by everyone whose knees 
 have trembled and whose pulse has gone to one hundred 
 and thirty. The mental distress of the situation comes 
 from the fact that these forms of reaction are ineffective, 
 indeed are quite absurdly in the wrong direction. 
 
 How to change the attitude of fear. The common advice 
 given to children to go directly and investigate any object 
 of which they are afraid is in general good. The going 
 and the handling of an object give the individual a form of 
 reaction which is coordinated and normal as a substitute for 
 the agitation and for the ineffective inner agitation. 
 
 Fear an emotion of complex beings. Kipling has made a 
 tale out of the evolution of fear. The stupid, slow-going 
 bullocks in a night stampede in the camp tell how they 
 fight and criticize the elephant as a coward. The bullocks 
 tell how they draw the guns. 
 
I50 PSYCHOLOGY 
 
 '' Then we tug the big gun all together -— Hey a — Hullah / 
 Heeyah ! Hullah I We do not climb like cats nor run like calves. 
 We go across the level plain, twenty yoke of us, till we are un- 
 yoked again, and we graze while the big guns talk across the plain 
 to some town with mud walls, and pieces of the wall fall out, and 
 the dust goes up as though many cattle were coming home." 
 
 ^^ Oh ! And you choose that time for grazing do you ? " said the 
 young mule. 
 
 ^^ That time or any other. Eating is always good. We eat till 
 we are yoked up again and tug the gun back to where Two Tails 
 is waiting for it. Sometimes there are big guns in the city that 
 speak back, and some of us are killed, and then there is all the 
 more grazing for those that are left. This is Fate — nothing but 
 Fate. None the less, Two Tails is a great coward. That is the 
 proper way to fight. We are brothers from Hapur. Our father 
 was a sacred bull of Shiva. We have spoken." . . . 
 
 Whereupon the elephant who has heard himself accused 
 of being a coward replies as follows : 
 
 ^^ Well," said Two Tails, rubbing one hind leg against the other, 
 exactly like a little boy saying a piece, ^^ I don^t quite know whether 
 you 'd understand." 
 
 ^^ We don't, but we have to pull the guns," said the bullocks. 
 
 ^^ I know it, and I know you are a good deal braver than you 
 think you are. But it 's different with me. My battery captain 
 called me a Pachydermatous Anachronism the other day." 
 
 ^^ That 's another way of fighting, I suppose ? " said Billy, who 
 was recovering his spirits. 
 
 ^* You don't know what that means, of course, but I do. It 
 means betwixt and between, and that is just where I am. I can 
 see inside my head what will happen when a shell bursts ; and you 
 bullocks can't." 
 
 ^^ I can," said the troop-horse. ^^ At least a little bit. I try not 
 to think about it." 
 
 ^^ I can see more than you, and I do think about it. I know 
 there 's a great deal of me to take care of, and I know that nobody 
 knows how to cure me when I'm sick. All they can do is to stop 
 my driver's pay till I get well, and I can't trust my driver." 
 
CERTAIN FUNDAMENTAL ATTITUDES 151 
 
 Two Tails stamped his foot till the iron ring on it jingled. 
 "Oh, I'm not talking to you. You can't see inside your heads." 
 
 '' No. We see out of our four eyes," said the bullocks. '' We 
 see straight in front of us." 
 
 '* If I could do that and nothing else you would n't be needed 
 to pull the big guns at all. If I was like my captain — he can see 
 things inside his head before the firing begins, and he shakes all 
 over, but he knows too much to run away — if I was like him I 
 could pull the guns. But if I were as wise as all that I should never 
 be here. I should be a king in the forest, as I used to be, sleeping 
 half the day and bathing when I liked. I have n't had a good bath 
 for a month." ^ 
 
 Fear and pathology. The physicians who deal with mental 
 pathology report fear as the most common form of modern 
 mental breakdown. The fears of our present-day lives are 
 not the fears of the forest, but they are subtle and disorgan- 
 izing. They cannot be classified merely as unpleasurable 
 agitations ; they arise from violent and disorganizing forms 
 of disrupted nervous activity. 
 
 Parental love and altruism. Parental love for offspring 
 has been described as an instinct. Here again we have to do 
 with a complex attitude which can be understood only when 
 one studies the forms of behavior w^hich the parent culti- 
 vates. Nature has so organized the higher animals that they 
 protect their young. Gradually the compass of these protec- 
 tive activities wddens until a mother may be wholly absorbed 
 in the care of her offspring. The evolution of many of the 
 complex forms of social life is directly traceable to the 
 efforts of parents to care for their young. Fiske, in a very 
 interesting essay on the evolution of altruism, has shown 
 how the care of the child has brought into the world a 
 mental attitude wdiolly beyond animal instinct. Among primi- 
 tive animals behavior was at first aimed at self-preservation, 
 With the growth of parental solicitude has come a form of 
 
 1 Rudyard Kipling, The Jungle Book, pp. 284, 287-289. The Century 
 Company, 1914. 
 
152 PSYCHOLOGY 
 
 behavior which is at times so strong that a mother will 
 sacrifice herself and with supreme gratification undergo all 
 kinds of hardships in doing for her child that which will 
 protect him and promote his welfare. This in turn, as Fiske 
 points out, leads to other altruistic acts and attitudes em- 
 bracing companions and acquaintances. Cultivated modes 
 of behavior may, as in this case, create mental values which 
 are entirely unintelligible if we think only of individual 
 self -protection. 
 
 Anger. Anger is a mental attitude which accompanies an 
 effort to throw off restraint. There may be blind rage in 
 which the angry man beats aimlessly at everything which 
 is within reach, or there may be the subtle studied anger 
 which step by step proceeds to the final attack. Watson has 
 called attention in his experiments with infants to the fact 
 that a new-born infant will be thrown into a rage if its move- 
 ments are restricted. Hold an infant's head perfectly still 
 and anger will appear. 
 
 Other emotions. The list of attitudes could be indefinitely 
 amplified. Jealousy, shame, bashfulness, surprise, awe, rever- 
 ence are all names of special attitudes which grow out of the 
 efforts of the individual to deal in some active way with the 
 world about him. They all reduce in the last broad analysis 
 to pleasurable and unpleasurable experiences, but this gen- 
 eral classification obliterates the distinctions which can be 
 productively retained if, instead of merely trying to classify 
 attitudes, one develops the formula of explanation which in- 
 cludes all the rich variety of human reactions to a complex 
 environment. 
 
 Emotions as fundamental forms of experience. The fore- 
 going paragraphs will be recognized by every reader as deal- 
 ing with that aspect of experience which has always been 
 referred to under the terms '' feeling " and '' emotion." The 
 importance of the feelings must not be underestimated by 
 the student of human life. Sensory impressions are of 
 
CERTAIN FUNDAMENTAL ATTITUDES 153 
 
 significance only as they arouse attitudes. It is the attitude 
 which reveals the individual ; and the attitude in turn is 
 the result of organized modes of response. The paths in 
 the nervous system along which sensory impressions travel 
 to their motor discharge, the central agitations which arise 
 in the nervous system as the sensory impressions are com- 
 bined and recombined, condition experience in a way that 
 cannot be overlooked by one who is interested in human 
 nature. Hum.an nature is what it is, not because of the 
 impressions which come to the eye and ear, but because of 
 the responses which are worked out through the central 
 nervous system. 
 
 Higher forms of experience as related to behavior. Thus 
 far we have been showing in a general way that attitudes are 
 related to reactions. The full significance of reactions for 
 individual mental life will become increasingly apparent as 
 the subsequent discussions canvass the different types of 
 organized behavior of human beings. We shall discover that 
 there are lower forms^f behavior and lower types of mental 
 attitude, and that the development of higher forms of expe- 
 rience involves the development of higher and more complex 
 forms of reaction. Indeed, the rest of our study wdll be a 
 study of human reactions and accompanying experiences. 
 The remainder of this chapter will be devoted to a study of 
 some of the more primitive and more fundamental attitudes. 
 
 Feelings of organic type. Many of the most primitive 
 adjustments of the motor organs of the body are internal 
 adjustments and have to do with the well-being of the body 
 itself. Accompanying these there is at all times a background 
 of feeling which colors all experience. There is the buoyant 
 feeling which one enjoys when he begins life on a bright, 
 clear day and the feeling of utter depression of a foggy day. 
 The reasons for such feelings can be understood from such 
 experiments as the following. The muscles of a waking 
 person are always under tension. Let the tension be tested 
 
154 PSYCHOLOGY 
 
 under conditions of varying stimulation. The individual can 
 be asked to show his muscular strength by means of a 
 dynamometer or simple apparatus for measuring the strength 
 of the grip. If such a test is made in a dark, silent room, 
 and a second test with the same person is subsequently made 
 in a room which is well lighted and full of sound, it will be 
 found that more work can be done in the latter case than 
 in the former. The additional light and sound have raised 
 the nervous and muscular tone to a higher level, so that 
 when the movement is undertaken, the motor impulses to 
 the muscles have the advantage of the higher initial tension. 
 It need hardly be pointed out that the conscious experience 
 of the reactor is different in the two cases described. 
 
 Flexor and extensor movements related to characteristic 
 attitudes. A second experiment is as follows : Let a person 
 be trained to make an outward swing of the arm with his 
 eyes closed. If a number of measurements are made, it is 
 possible to determine with great accuracy the range of error 
 of these movements. If the movements are made when the 
 senses are in a quiet condition without special stimulation, 
 they will not be of exactly the same length in successive 
 trials, but they will not differ widely from each other. After 
 these preliminary tests, let the reactor be given a strong 
 bitter or sweet taste sensation. The result will be that the 
 arm, in common with the other muscular organs of the body, 
 will take on a different tension. The tension in the case of 
 a sweet stimulus will tend to favor outward expansive move- 
 ments ; the tension in the case of a bitter stimulus will tend 
 to favor inward contracting m.ovements. The result will be 
 increased movements in these directions, even when the 
 person tries to move as before. In short, bitter tastes and 
 sweet tastes result in inner muscular tensions. 
 
 Changes in circulatory movements as parallels of con- 
 scious changes. One of the systems of muscles which is 
 most noticeably affected by any change in stimulation is the 
 
CERTAIN FUNDAMENTAL ATTITUDES 155 
 
 system in control of the circulatory activities. If a recording 
 apparatus is so adjusted as to give a record of the rate and 
 intensity of the heartbeat, it will be found that there is a 
 constant rise and fall in the rate and intensity of circulatory 
 activity. The rise and fall can be shown in striking degree 
 by using in the course of the experiment some marked 
 stimulus, but even when no special stimulus is applied to 
 the organs of sense, there is a continuous flux and change 
 in the circulatory activities. Here, again, it is unnecessary 
 to point out that consciousness is constantly changing, and 
 that it changes most noticeably with the application of an 
 external stimulus. Indeed, so close is the relation between 
 activity and sensation in this latter case that it may safely 
 be said that there is never a change in sensory excitation 
 without a parallel change in circulatory activity. 
 
 Disappointment as negative emotion. Another case of this 
 internal type of reaction is to be found in the fact that the 
 body is from time to time thrown back on itself. For ex- 
 ample, one starts to go about some ordinary task and finds 
 that the energy he had mustered up for the work cannot 
 be used because he cannot find the tools for his work. The 
 energy which was to be expended in doing the work is 
 thrown back into the body, and the inner agitation is accom- 
 panied by what we call in ordinary life disappointment. 
 Here the nervous agitation is in the nature of a disagree- 
 able stopping of movements which were originally directed 
 outward but have suddenly been thrown inward. 
 
 External attitudes. There are many forms of reaction 
 with an outward turn which are less emotional in character 
 because the content of experience is less personal. We use 
 in such cases terms like ''satisfaction" or ''interest." The 
 man who makes a good stroke in golf enjoys- it and gets 
 satisfaction out of it, but he does not have so intense a per- 
 sonal experience as he has when he makes a bad stroke. 
 .The successful performance issues in a series of impressions 
 
IS6 PSYCHOLOGY 
 
 and ideas rich in content ; the unsuccessful act arouses vio- 
 lent internal circulatory reactions and unpleasant tensions of 
 all the muscles of the body. 
 
 Attention as an attitude. There is one very general fact 
 with regard to reactions to external objects. The individual 
 either turns toward an object, looking toward it, reaching 
 out for it, and bracing himself to deal with it, or else the 
 individual turns away from an impression, neglecting it or 
 actually rejecting it. The attitude side of these various forms 
 of response is described by a general term, — the term ''at- 
 tention." One attends to an object or is interested in it, or 
 in the other case he neglects it or exhibits a lack of interest 
 or concentration on it. 
 
 Experiment to demonstrate tension. Attention is the atti- 
 tude of reacting to an impression. The physical symptoms 
 of attention are well known ; there is the strained muscle, 
 the fixed gaze, the leaning forward to catch the new im- 
 pression which will in turn arouse more action. Much of 
 the reaction exhibited in a state of attention is for the pur- 
 pose of focusing the organs of sense on the source of the 
 sensations. The infant is constantly trying to get into contact 
 with everything for the purpose of getting more impressions. 
 
 All through life there is a tendency to move in the direc- 
 tion of an object which is in the center of attention. This 
 is shown experimentally as follows : Let the person to be 
 tested rest his hand on some recording apparatus which 
 moves with very little friction. A board suspended by a 
 long string and carrying a tracer at one end is a very good 
 apparatus with which to make this experiment. Now let the 
 subject close his eyes and think intently of his hand. The 
 recording point will make short excursions back and forth, 
 for there is no such condition as one of absolute rest of the 
 hand muscles, and under the conditions arranged very slight 
 movements are sufficient to produce a record. After noting 
 the range and kind of movement which will be made when 
 
CERTAIN FUNDAMENTAL ATTITUDES 
 
 157 
 
 one thinks as steadily as he can of the hand, let the reactor 
 think intently of some object at his right or left. Let him 
 make an imaginary journey or draw in imagination some 
 simple geometrical figure. The result will be that the move- 
 ments of the recorder will be radically changed. There will 
 often be a tendency for the 
 new movement to take on 
 a form directly related to 
 the new subject of thought, 
 but in any case there will 
 be a change from the type 
 of movement which appears 
 when attention is concen- 
 trated on the hand, even if 
 the form of the new move- 
 ment is not directly trace- 
 able to the new experience. 
 Fig. 45 shows the records 
 of involuntary hand move- 
 ments of the type described. 
 
 Various forms of atten- 
 tion. Such an experiment 
 reveals the reason for the 
 use of words like ''atten- 
 tion, " ' ' concentration, ' ' and 
 '' interest " as partial syno- 
 nyms. The focusing of ac- 
 tivity on an object arouses 
 an emotional attitude ; hence we are justified in treating 
 attention and feeling as closely related. 
 
 The explanation of attention will perhaps be understood 
 most readily through consideration of those negative cases 
 where the individual neglects the objects about him, as 
 when we do not count the number of windows in a room. 
 Here the . impression goes into the nervous system, but 
 
 Fig. 45. Involuntary hand movements 
 made by the right and left hands of 
 an observer who is thinking of a build- 
 ing situated in front of him 
 
 The hands begin at the two points A, A ; 
 the building lies in the direction of the 
 movement which is here represented by 
 the downward extension of the two lines. 
 (After Jastrow) 
 
158 
 
 PSYCHOLOGY 
 
 is not made a center of any direct reaction. The impres- 
 sion is lost in the mass of reactions ; it is not individual- 
 ized. We say that it does not receive attention or arouse 
 interest. 
 
 Sympathy with fellow beings. Such general comments 
 on attention lead to the treatment of special cases. When- 
 ever we see a fellow being trying to do something, we tend 
 to share in the activity. The man who is lifting a weight 
 arouses all who see him to like effort. The singer who is 
 taking a high note will be followed by his audience with 
 sympathetic muscular efforts. Attention in these cases 
 
 issues in svmpathetic 
 action. 
 
 Sympathy involved 
 in all recognition of 
 objects. Sympathy ex- 
 tends far beyond one's 
 fellow beings. All 
 that we include under 
 the term '' aesthetical 
 appreciation" belongs 
 under the same head- 
 
 FiG. 46. Unaesthetical balance 
 
 The two black spots are evidently not well sup- 
 ported by the fulcrum shown in the figure. There 
 is a restless feeling that the large figure should be 
 supported by the observer 
 
 ing. For example, let an observer look at an unsymmetrical 
 drawing, such as that shown in Fig. 46. The long horizon- 
 tal line with the black figures at its ends is not well sup- 
 ported at the fulcrum given in the figure. The feeling of 
 lack of balance in th/is figure is directly related to an active 
 tendency on the part of the • observer to offer his support 
 to the line as it carries the larger figure, and this tendency 
 to action which is inspired by the figures is accompanied by 
 a distinctly disagreeable experience, because it is continually 
 ineffective in producing its purpose. Examples of the feel- 
 ing of pleasure which comes from harmonious complexes 
 can be derived from the study of Greek architectural forms. 
 The Greeks recognized the fact that a column with perfectly 
 
CERTAIN FUNDAMENTAL ATTITUDES 159 
 
 straight lines is not an aesthetic object. Such a column always 
 seems to be weaker in the center than at the extremities, 
 where there are larger masses of matter. There is therefore 
 a feeling of unrest inspired in the observer lest the column 
 should give way in the center, where the tension is great 
 and the material relatively reduced. The Greeks, accord- 
 ingly, made their columns larger in the middle than at the 
 extremities, and the result was that the observer, seeing the. 
 reenforcement at the critical part of the column, has a feel- 
 ing of satisfaction rather than of unrest in looking at the 
 lines. The term '' sympathy " is not used here as a figure 
 of speech. There is a real muscular tension involved in 
 observing a column lifting a weight, and through this 
 tension the observer enters into the situation as an active 
 participator. 
 
 Illusion due to muscular tension. The presence of mus- 
 cular tensions related to perception of weight can be demon- 
 strated in certain special cases. If one prepares two blocks of 
 exactly the same objective weight but of very different sizes, 
 so that one is, for example, about a foot cube and the other 
 three inches cube, the observer will find when he comes to 
 lift these two blocks that the smaller block seems decidedly 
 heavier than the larger one. The explanation of this fact 
 is to be found in the muscular preparation of the observer 
 when he first looks at the two blocks. The visual expe- 
 rience from the small block leads him to prepare to do a 
 small amount of work in lifting it, while the visual impres- 
 sion of the larger block is recognized in terms of a totally 
 different kind of muscular organization, which may be de- 
 scribed by saying that the observer prepares to do more 
 work in lifting the large block than he prepares to do in 
 lifting the smaller one. When, with these differences of 
 preparation, the observer lifts the two blocks, he finds that 
 his preparation does not coincide with the demands forced 
 upon him .through his direct contact with the blocks. There 
 
i6o PSYCHOLOGY 
 
 is, therefore, a sharp disagreement between the original 
 preparation based on vision and the subsequent experience 
 dependent on touch. This disagreement expresses itself in 
 the form of an illusion with regard to weight. This illusion 
 is not due to sensations merely, but involves also prepa- 
 ration for active response. There can be no doubt that 
 whenever one looks at any ordinary object of manageable 
 size, he prepares to lift it. The preparation consists in an 
 incipient act, and this act is the physiological parallel of 
 an important phase of the observer's mental process of 
 recognition. 
 
 Such muscular tensions common to many experiences. 
 This illusion of weight and similar facts from practical life 
 throw much light on the nature of the organization which 
 was referred to when it was stated, in discussing the aesthetic 
 attitude toward a column, that one sympathizes with the 
 column in the work which it does in supporting the mate- 
 rials placed upon it. There is a certain direct perceptual 
 estimation of the fitness of the column to do its work. 
 That estimation expresses itself immediately in the mus- 
 cular tension which is aroused in the observer as an inte- 
 gral part of the process of recognition. If the column is 
 inadequate, the observer is led to a strained attitude of 
 assisting it ; if the column is adequate to its task, there is 
 an attitude of satisfied recognition. 
 
 All consciousness a form of sympathetic attention. Thus 
 we find that as human attitudes become more complex they 
 are something more than feelings or emotions ; they include 
 also sympathies and discriminations which become parts of 
 higher intellectual recognitions. When one sympathizes with 
 a column, it is not a mere vague, general response ; it is a 
 discriminating response, bringing one into personal relations 
 to the outer world. In all the higher stages of mental 
 development one knows objects through one's sympathies 
 with them. 
 
CERTAIN FUNDAMENTAL ATTITUDES l6l 
 
 The discussion of attitudes leads us thus to broad con- 
 clusions about the nature of consciousness. Consciousness 
 is a function through which the individual attempts to put 
 himself in harmony with the outer world. He translates 
 the world into terms of his own responses and thus makes 
 the objects outside of himself a part of his own inner life. 
 After he has thus taken the outer world into his mental 
 life, a new possibility arises — that of carrying back into 
 the external world some of the rearrangements which are 
 first worked out in the purely subjective sphere. The indi- 
 vidual, by first fitting himself to the outer world, learns how 
 to mold the outer world to meet his inner needs and desires. 
 
 Attitudes as related to higher processes of recognition. 
 Psychology must study, then, those attitudes of feeling and 
 sympathy by which the inner world absorbs impressions and 
 makes them into personal experiences. It must then take 
 up the higher processes through which inner experience 
 is made effective in controlling the world from which 
 impressions first came. 
 
CHAPTER VIII 
 
 COMBINATION AND ARRANGEMENT OF 
 
 SENSATIONS 
 
 Sensory experience always complex. The arrival of a 
 sense impression in the central nervous system has been 
 shown in eariier chapters to be only the first step in a 
 series of processes in which this impression is combined 
 with other sensory impressions and carried forward to a 
 motor discharge. It is hterally true that no sense impres- 
 sion ever comes into the central nervous system alone. 
 Even if we think of only a single sense organ, we realize 
 that it sends to the central nervous system at every 
 moment a series of impressions rather than a single sen- 
 sation. Thus, when the eye is stimulated by a colored 
 surface, it is not a single sensation which arrives in con- 
 sciousness, but a whole mass of sensations. The different 
 parts of the field would yield various shades and intensi- 
 ties even if the receiving cells in the eye were all alike 
 and all prepared to respond with absolute uniformity to 
 the stimulus. But, as was shown in the chapter on sen- 
 sation, various parts of the retina are different in their 
 ability to receive impressions. The result is that a colored 
 surface is the source of a most complex series of sensations. 
 
 The matter is further complicated by the simultaneous 
 arrival of impressions through different senses. Thus we 
 not only see a surface, we also touch it and may smell 
 it or hear it vibrate. At any given moment there are 
 impressions reaching the senses not from a single object 
 alone but from various objects. As we look at a colored 
 
 162 
 
COMBINATIONS OF SENSATIONS 163 
 
 surface we receive touch sensations from contact with our 
 clothing and from the floor on which we stand ; we hear 
 sounds from the next room and breathe in odors which 
 have no relation to the colored surface. 
 
 Sensation combinations or fusions. In the midst of all 
 this world of sensations there must be selection and com- 
 bination. The individual works out, in the interests of 
 practical life, certain units of experience in which sensa- 
 tions are fused with each other and distinguished from 
 the rest of the world. For example, one sees an orange. 
 What he really sees is a complex background in the midst 
 of which there is a little patch of orange shade. He gets 
 a mass of odors, but attaches a particular aroma to the 
 particular patch of color. He is able, in the course of 
 this attention to his experience, to recognize that the color 
 and the aroma are nearer his right hand than his left. 
 What he has done in thus fusing a group of sensations 
 and locating the fused group on the right is designated 
 in technical psychological language by the term ''percep- 
 tion." One perceives objects ; that is, one recognizes cer- 
 tain groups of sensations as belonging together and as 
 different from the rest of the world. 
 
 Space not a sensation, but a product of fusion. In the 
 process of perceiving the world the individual develops 
 certain types of conscious experience which must be dis- 
 tinguished from sensations. Space is such a product of 
 organized experience. Space results from the fact that 
 sensations take on what we may call ''togetherness." To- 
 getherness is a product of fusion. The counterpart of 
 togetherness is separateness. The perceived orange is dis- 
 tinguished from other objects. The whole complex of 
 togetherness and separateness ultimately gets arranged into 
 a general map or system. In this system there ultimately 
 comes to be a right and left, an up and down. The world 
 is now recognized as arranged in order. 
 
l64 PSYCHOLOGY 
 
 Tactual space as a simple example of fusion. One of 
 
 the earliest experimental studies in space perception dealt 
 with the spatial arrangement of tactual experiences. In 
 his effort to find some method of testing the sensitivity 
 of the skin, Weber measured the distances which must 
 lie between two stimulated points on the skin in different 
 parts of the body before the points may be recognized as 
 separate. He found that in much-used regions, such as 
 the ends of the fingers, the lips, and the tongue, the distances 
 which are necessary between points, in order that they may 
 be distinguished, are very small, often less than a single 
 millimeter ; while on the upper arm or the middle of the 
 back the points must be separated by three to six centi- 
 meters in order to be recognized as two. Furthermore, as 
 has been abundantly shown since the time of Weber, there 
 is the greatest uncertainty in the estimation of distances 
 and directions in the regions where discrimination of points 
 is difficult. 
 
 Subjective and objective space. On the basis of these 
 facts we may emphasize the difference between external 
 space and our recognition of space. Two millimeters of 
 extension on the middle of the back are for the geometri- 
 cian equivalent in all respects to the same distance on the 
 finger. For the observer who perceives these two regions 
 through the sense of touch, the recognition of the two dis- 
 tances is not a geometrical fact, uniform for all parts of the 
 body, but a complex of varying experiences. 
 
 Perception and training. Experiments of the kind which 
 Weber tried can be carried farther. Thus, it has been 
 shown that after a little training regions of the skin where 
 the discrimination was relatively difficult can be developed 
 so as to permit of very much finer discrimination than 
 that which was exhibited at first. In other words, without 
 any radical change in ^ the sensory conditions, practice will 
 rapidly refine space perception. Again, if any region of the 
 
COMBINATIONS OF SENSATIONS 165 
 
 skin is stimulated by means of a continuous line rather than 
 by two separate points, it will be found that the greater 
 mass of sensations received from the line facilitates dis- 
 crimination. A line can be recognized as having exten- 
 sion when it is about one third as long as the distance 
 between two points which are just discriminated as sepa- 
 rate from each other. The difficulty of discriminating two 
 points when they are presented alone is not due to the 
 character of the sensations from the points, but rather to 
 the difficulty of discriminating them without the aid of a 
 more complete sensory series derived from the stimulation 
 of points between. 
 
 Development of spatial arrangements in the course of 
 individual experience. In our search for an explanation 
 of the facts of tactual perception of space, let us ask 
 what is the course of individual development. Anyone 
 who observes an infant recognizes that early in life there 
 is the greatest uncertainty in locating stimulations on the 
 skin. If the skin of an infant is vigorously stimulated 
 either by some accident or by the efforts of someone who 
 is interested in making an experimental investigation, it 
 will be found that the infant moves its hands about in the 
 most indefinite fashion, often failing entirely to reach the 
 irritated spot. We can understand the infant's difficulty 
 if we try to locate with precision some point which has 
 been stimulated on the skin of the upper arm. The infant 
 has sensation enough, just as we have when stimulated in 
 an undeveloped region, but the sensation is not properly 
 related to other sensations. It has no recognized relations 
 which give it a definite place in a well-ordered sequence 
 of tactual or visual qualities, because the well-ordered 
 sequence has not yet been built up. An established series 
 of relations of some definite kind is necessary before the 
 sensation can enter into distinct spatially-ordered percepts. 
 Until a definite series of space notions is developed, the 
 
1 66 PSYCHOLOGY 
 
 sensation will enter only into vague fusions, and localiza- 
 tion will be altogether incomplete. The change from vague 
 to definite localization requires much experience and atten- 
 tion. Indeed, it is a fact easily verified that no sensation 
 becomes definite in its relations until the practical needs 
 of life demand such definiteness. The reason w^hy an 
 adult discriminates points on the end of the finger and 
 not those on his back is that in the course of life he 
 has been obliged to use his finger sensations. Use has 
 led to an arrangement of points, to the development of 
 what may 'figuratively be called a map. This map is devel- 
 oped by recognizing again and again the relation of a 
 finger to the palm of the hand and of the palm of the 
 hand to the elbow, and so on, until the various parts of 
 the body are thought of as in a fixed relation. The map 
 then takes on a kind of independence and remains in 
 the mind as distinct from any particular sensations. The 
 adult knows the parts of his body even when they are 
 not actually stimulated at the moment. 
 
 Vision and movement as aids to touch. This process of 
 developing definiteness in tactual localization has undoubtedly 
 been very greatly facilitated by the presence of vision. Even 
 in adult life one can often find himself making his experience 
 of a tactual stimulation more exact and complete by looking 
 at the point irritated, thus relating the tactual sensation to 
 visual sensations. The process of localization of tactual sen- 
 sations is also very largely dependent on movement. It is an 
 empirical fact that the perceptual arrangement of skin sensa- 
 tions is most complete in the most mobile parts of the body. 
 A number of careful experimental observers at one time ex- 
 plored the whole surface of the skin and showed that in any 
 given region that part w^hich is most mobile is the part on 
 which points are most easily discriminated. Thus the hand 
 is the most highly developed part of the arm ; the foot is the 
 most highly developed part of the leg. 
 
COMBINATIONS OF SENSATIONS 167 
 
 Tactual percepts of the blind. In some respects the tactual 
 perception of blind persons is more highly developed than 
 that of persons who have vision. The blind are not supplied 
 with better organs of touch, but they make more discriminat- 
 ing use of such experiences as they receive through the skin. 
 They also make more use of movements than do normal per- 
 sons, as may be observqd in the fact that they restlessly 
 explore every object which comes within their reach. The 
 limitations of the space perception of the blind appear when 
 complex objects are presented for recognition. When the 
 mass of sensory impressions is great, the discrimination and 
 fusion of these sensations become very difficult. This fact is 
 strikingly illustrated by the history of the raised letters used 
 in books for the blind. The most natural way of producing 
 such books, and the way which was followed at first, was to 
 print in raised lines the same letter forms as were used for 
 persons who read visually. For vision the complex lines of 
 ordinary printed letters offer no difficulties, because vision is 
 so highly organized that it discriminates easily the ordinary 
 printed forms. No one realized that touch being so much 
 coarser than vision would discriminate forms less easily. 
 Such proved, however, to be the case. The letters for the 
 blind have, accordingly, been simplified until in one of the 
 best and most recent systems the letters are made up entirely 
 of points. These points are easy to distinguish and, being 
 placed near one another, are also easy to recognize in groups. 
 
 Wundt on the tactual perception of the blind. The char- 
 acter of tactual perception in the case of the blind is thus 
 illustrated and discussed by Wundt : 
 
 The way in which the blind alphabet is read shows clearly 
 how the space ideas of the blind have developed. As a rule, the 
 index fingers of both hands are used in blind reading. The right 
 finger precedes and apprehends a group of points simultaneously 
 (synthetic touch), the left finger follows somewhat more slowly 
 and apprehends the single points successively (analytic touch). 
 
i68 PSYCHOLOGY 
 
 Both the synthetic and analytic impressions are united and referred 
 to the same object. This method of procedure shows clearly that 
 the spatial discrimination of tactual impressions is no more imme- 
 diately given in this case than in the case where vision w^as present, 
 but that in the case of the blind the movements by means of which 
 the finger that is used in analytic touch passes from point to point 
 play the same part as did the accompanying visual ideas in the 
 normal cases with vision. 
 
 Lotze's local signs. Another method of describing the tac- 
 tual perception of space is that adopted by Lotze, one of the 
 earliest of the writers on physiological psychology. Every 
 point on the surface of the body gives rise, said Lotze, to a 
 tactual sensation which in addition to its general quality and 
 intensity as a tactual sensation has a peculiar and character- 
 istic shading due to the structure of the skin at the particular 
 point where the stimulus is applied. Thus, if the same pres- 
 sure is applied to the lips and the forehead, the resulting sen- 
 sations will, in spite of general likeness, be slightly different 
 in the two cases, because there is soft muscular tissue under 
 the skin of the lips and hard bony tissue under the skin of 
 the forehead. These slight differences between tactual sen- 
 sations which are due to locality lead the observer to arrange 
 his tactual sensations in certain systems or series. The quali- 
 tative shadings are thus transformed into spatial series. The 
 qualitative differences come to signify position and are con- 
 sequently designated as local signs. Their character as local 
 sig7is is derived from the spatial system to which they are 
 referred ; they are individually merely qualitative differences. 
 
 Inner tactual factors. The factors which enter into tactual 
 space percepts are probably derived in part from the inner 
 organs, such as the semicircular canals, the joints, and the 
 muscles. From the semicircular canals, as pointed out in 
 an earlier chapter, there is a constant stream of excitations 
 reaching the central nervous system with every change in 
 the position of the body. The limbs in their movements 
 
COMBINATIONS OF SENSATIONS 169 
 
 give rise to sensations in the joints and muscles. While the 
 child is exploring the surface of his body and attaining the 
 degree of ability to discriminate points which is shown by 
 Weber's experiments, he is also learning through muscle 
 sensations to recognize distances away from the surface of 
 his body by reaching for things about him. He is learning 
 through the sensations from his semicircular canals that 
 there is a fundamental distinction between '' right side up " 
 and oblique or inverted positions. He is learning through 
 joint sensations to recognize how many steps must be taken 
 to cross certain stretches of space. 
 
 Space not attached to any single sense. The striking 
 fact is that ultimately all these different sensory factors are 
 arranged into the same space form. There is not one tactual 
 space, and another space for muscle sensations, and another 
 for joint sensations. All are fused into a single system. 
 The spatial order is a relational fact ; that is, it is a product 
 of the fusion or putting together of sensations. Whenever 
 sensations are fused into the spatial relation they take on a 
 character different from that which can be assigned to them 
 when they are considered alone. 
 
 General conclusions regarding tactual space. From this 
 survey of the facts of tactual space we have derived several 
 important conclusions. Space is a complex. Space is not a 
 sensation quality, but a relational form of experience. Tactual 
 space is not explicable without reference to the general for- 
 mula of organization which includes other sensations also. 
 
 We are, accordingly, justified in postponing the general 
 explanation of space perception until we have taken up the 
 facts regarding the arrangement of auditory and visual sen- 
 sations in the spatial form. 
 
 Auditory recognition of location. Experiments on the 
 
 localization of sounds may be made as follows : Let a sound 
 
 ^be produced in the median plane, which passes vertically 
 
 through the head from in front backward, midway between 
 
I/O PSYCHOLOGY 
 
 the two ears. If the sound is simple in quality, as, for ex- 
 ample, a sharp click of some kind, and the observer's eyes 
 are closed so as to eliminate vision and make him entirely 
 dependent on hearing, the localization of the sound will in 
 the majority of cases be erroneous. The sound will always 
 be localized somewhere in the median plane, but its exact 
 position in this plane cannot be recognized. If, on the other 
 hand, the sound is moved slightly to the right or left of the 
 median plane, it will be found that the observer can local- 
 ize the sound with great accuracy. The explanation of the 
 observer's ability to locate sounds coming from the side is 
 simple and depends chiefly upon the fact that the observer 
 receives from such a sound different intensities of sensation 
 in the two ears. P>om. all positions in the median plane the 
 two groups of sensations received in the two ears have equal 
 intensities, whereas the intensities of sounds received in the 
 two ears from any position outside of the median plane are 
 unequal. 
 
 Influence of movements in auditory experience of position. 
 Undoubtedly here, as in the case of tactual space, the facts 
 of movement are of great significance in organizing sensory 
 experience. If a sound on one side of the head is more 
 intense than the sound on the other, there will be a strong 
 tendency to readjust the head in such a way that the stronger 
 sound shall be made even more intense and the weaker 
 group of sensations shall be made still fainter by the move- 
 ment of the head. If a sound is in the median plane and 
 there is difficulty in getting at its precise localization, there 
 is frequently a noticeable effort on the part of the observer 
 to bring the head into such a position that a more satisfac- 
 tory determination of position shall be possible through a 
 modification of the intensities of the sensations from the two 
 ears. Often auditory perception issues in a movement which 
 tends to bring the eyes toward the source of the sound. 
 The same tendency which was noted in the discussion of 
 
COMBINATIONS OF SENSATIONS 171 
 
 tactual sensations to fuse various kinds of sensations into a 
 single spatial system is obvious in this effort to supplement 
 hearing by vision. 
 
 Qualitative differences and localization. The explanation 
 which has been presented can be made more elaborate by 
 giving attention to qualitative differences as well as to differ- 
 ences in intensity in the two groups of sensations received 
 by the two ears. There can be no doubt that the external 
 pinna of the ear modifies somewhat the character of the 
 sound as it enters the auditory canals. If a complex sound 
 strikes the pinna from in front, its quality will be different 
 from that which would result if the same sound is carried 
 into the ear from behind. As a result of these qualitative 
 modifications produced by the external ear, we are able to 
 localize sounds even in the median plane, provided they 
 are of complex quality. The human voice, for example, in 
 the median plane of the head, can usually be recognized 
 with great precision as coming from a point in front or 
 behind. This is due to the fact that the voice is complex 
 in quality. 
 
 Distance of sounds recognized only indirectly. The dis- 
 cussion of the recognition of the direction from which 
 sounds come may be supplemented by reference to the fact 
 that the recognition of the distance of sounds also involves 
 a large body of organized experiences. If one hears the 
 human voice sounding very faintly in his ears, his frequent 
 experience with voices and their normal intensity when the 
 speakers are near at hand will lead him to recognize that 
 the person speaking is far away. Furthermore, the qualita- 
 tive character of the sound as well as its intensity is modi- 
 fied by the remoteness of its source, the elements of the 
 sound being less distinct when it is transmitted from a 
 great distance to the ear. The intensity and quality are, 
 accordingly, both utilized in interpretations of distance so 
 long as the sound is familiar. 
 
1/2 PSYCHOLOGY 
 
 Unfamiliar sounds difficult to locate. In contrast to the 
 relatively easy estimation of the distance of a familiar sound, 
 it is extremely difficult to estimate the distance of the source 
 of an unfamiliar sound. An experiment may be tried by 
 producing an unfamiliar sound, such as that which results 
 from snapping a card in the neighborhood of an observer's 
 head. Until this sound has become familiar the errors in 
 estimation of distance will be very noticeable. 
 
 Visual space and optical illusions. If we turn from audi- 
 tory space perception to visual experiences, we find a rich 
 variety of examples which show how complex is the process 
 
 Fig. 47. Miiller-Lyer illusion 
 
 The length of the horizontal line A is equal to the length of the horizontal line B. 
 (For further discussion of the figure see text) 
 
 of arranging sensations in a spatial order. There are certain 
 cases of incorrect perception of length and direction of 
 figures in plane surfaces, constituting what are known as 
 geometrical optical illusions. These are especially clear 
 examples of complex perception. Take, for example, the 
 illusion represented in Fig. 47. The two lines A and B are 
 in reality equal to each other, but the observer will recog- 
 nize at once that they seem to be of different lengths. The 
 retinal image of each line is distmct and clear ; the apparent 
 inequality cannot, therefore, be attributed to any confusion 
 in the retinal processes ; it must be attributed to some kind 
 of perceptual complexity. The explanation of the source of. 
 
COMBINATIONS OF SENSATIONS 173 
 
 this illusion has been the subject of much discussion, and 
 it is probably true that no single statement will account for 
 the apparent inequality of A and B, In a general way it 
 may be said that one cannot look at A and B without 
 including in his field of vision the oblique lines, and the 
 oblique lines are such striking and unfamiliar additions to 
 the horizontal lines that they are not neglected as they 
 should be in perceiving the length of the horizontals. If, 
 in addition to this general statement, we attempt to show 
 in detail how the oblique lines affect the horizontals, there 
 are a number of facts which may be noted. The oblique 
 lines produce less of an effect upon some observers than 
 upon others. This can be shown by making quantitative 
 determinations of the intensity of the illusion. For this 
 purpose one of the figures of the pair under discussion is 
 made adjustable, and the observer sets it until it seems to 
 him equal to the other figure. When the two seem equal 
 they will be in reality different. The amount of difference 
 can now be readily measured, and the results from various 
 observers compared. Not only are the results of such meas- 
 urements different for different observers, but the same indi- 
 vidual will at various times give different results. 
 
 Effects of practice. One especially significant case of in- 
 dividual variation is that in which the observer deliberately 
 sets about comparing the figures a great number of times 
 for the purpose of becoming familiar with them. Three 
 stages of change in interpretation show themselves in such 
 a practice series. First, the observer takes a general view 
 of the whole figure, as does the ordinary observer who 
 looks casually at the illusion ; he gets in this case a strong 
 illusion. Second, the observer tries to look at the long lines 
 and neglect the obliques ; that is, he makes an effort to 
 overcome the disturbing influence in a negative way. During 
 this period of conscious neglect of the obliques the illusion 
 grows somewhat weaker, but it does not disappear. Finally, 
 
174 PSYCHOLOGY 
 
 in the third stage, the observer reaches the point where 
 there is no need of an effort to neglect the obUques. In- 
 terpretation may be said to be so completely worked out in 
 this stage that the obliques and the long lines fall into their 
 proper relations without interfering with one another. Each 
 is included in the percept, but in its true significance. At 
 this stage the illusion is entirely overcome. 
 
 Percepts always complex. Such facts as these make it 
 clear that a visual percept includes all the factors in the 
 field of vision. If these factors are conflicting, they may 
 result in grotesque misinterpretations. If, on the other 
 hand, they are thoroughly assimilated into the percept, they 
 
 -i h 
 
 Fig. 48. Illusion of contrast 
 
 The middle portion of the short horizontal line marked off by the verticals seems 
 longer than the equal distance marked off in the long horizontal line 
 
 take their appropriate relations and no longer disturb the 
 total process of perception. 
 
 Contrast. A great many other illustrations could be 
 brought forward to show the relation of one part of the 
 visual field to all other parts. Thus, one cannot look at a 
 line on a large blackboard and fail to be influenced in his 
 estimation of the length of the line by the large surround- 
 ing space. Conversely, a line drawn on a small sheet of 
 paper is always interpreted in terms of the paper as either 
 relatively long or relatively short. Objects seem very differ- 
 ent in size when seen outdoors and again in a small room. 
 Fig. 48 illustrates this principle by showing a short central 
 line as part of a long line in one case and as part of a 
 short line in a second case, with the result that the central 
 line seems to be of different lengths in the two cases. 
 
COMBINATIONS OF SENSATIONS 175 
 
 Common facts showing size to be a matter of relations. 
 
 Other complications than those from the surrounding visual 
 field also influence one's perception of size. The natural 
 standards of size which depend upon familiarity and upon 
 the relations of objects to one's own body are constantly 
 influencing perception. Time and again descriptions have 
 been given by observers of the fact that a road seems 
 longer the first time one passes over it, when all the 
 sights are unfamiliar ; and many have also referred to the 
 fact that places known in childhood always seem small when 
 revisited in mature life. 
 
 Physiological conditions of visual perception. The signifi- 
 cance of all these facts for our understanding of visual space 
 is not hard to find. Putting the matter in physiological 
 terms, we may say that when series of visual stimulations 
 from a given line or figure reach the visual center, they find 
 there a larger series of excitations from other points on the 
 retina and a series of organized modes of response derived 
 from past experience. Each excitation takes its place in 
 this complex. 
 
 Psychological statement. Putting the same matter in psy- 
 chological terms, we may say that every sensation becomes 
 part of a fixed order. This order or spatial arrangement is 
 something other than the sensations ; it is a product of 
 perceptual fusion. 
 
 Photographic records of percepted movements. A clearer 
 understanding of the matter will be reached by considering 
 the results of photographic investigations, in which the path 
 of the eye movement in looking over certain illusory figures 
 has been determined. In Fig. 49 there is presented one of 
 the most striking of the illusions of direction. The long lines 
 are in reality parallel with each other, but the obliques are 
 far too distracting to permit the ordinary observer to recog- 
 nize the true relations between the parallel lines. Fig. 50 
 shows another illusion of direction. The oblique lines are 
 
176 
 
 PSYCHOLOGY 
 
 parts of a single line, but seem to extend in slightly different 
 directions because of the interrupting space between the 
 
 Fig. 49. Zoilner illusion 
 The long lines are parallel with each other 
 
 parallels. Fig. 5 1 shows the paths in which photographs indi- 
 cate that the eye of an observer moved in attempting to look 
 at the illusions discussed. In Fig, 51, ^, the movement over 
 the Zoilner pattern is shown. It is evident from the move- 
 ments indicated in the photographs that the sensation factors 
 are not fully mastered so as to permit coordinated move- 
 ments along the parallel lines. The result is that though 
 these lines give perfectly clear retinal images, they do not 
 
 stand in their true relations in experience. 
 The photographs show that often there 
 is sufficient fusion of the sensory factors 
 to permit a single movement in follow- 
 ing a line, and this single movement is 
 in the general part of the field of vision 
 in which the line lies, but it is only a 
 gross general approximation to the line. 
 This corresponds exactly to the fact that 
 the experience of the figure consists of 
 a gross general perception of the long 
 line and its obliques. One observer, after these preliminary 
 photographs of his eye movements in looking at the Zoilner 
 
 ^B 
 
 Fig. 50. Poggendorff 
 illusion 
 
 A^ B are parts of the same 
 straight line 
 
COMBINATIONS OF SENSATIONS 
 
 3>r 3. 
 
 177 
 
 Fig. 51. These figures show the path followed by the eye of an observer 
 in examining certain of the foregoing illusions 
 
 In each of the figures the path of the eye movement is indicated by a supplemen- 
 tary line. The numbers placed along these supplementary lines indicate the points 
 at which a pause was made in the course of the eye movement. In Fig. 51, A, the 
 observer was attempting to follow the long line of the illusion. It will be noticed 
 that he departs from the long line, and at the extreme end of the movement, as at 
 2 and 5, makes a short corrective movement by which he again fixates the long 
 line. In Fig. $1, B, the distracting influence of the vertical lines is obvious, as is also 
 the difficulty of moving the eye across the open space in any such way as to reach 
 the point of interconnection between the vertical and oblique lines. In Fig. 51, C, 
 it will be noted that the eye movement is very free in that part of the figure which 
 is overestimated, and much restricted whenever the eye approaches one of the 
 acute angles. This is indicated by the frequent pause in 3, 4, 6, 7, 8, 9. In 8 it 
 will be noted that the eye is deflected from the horizontal line by the oblique 
 
1/8 PSYCHOLOGY 
 
 pattern, put himself through a series of quantitative tests 
 with the figure. In this practice series he gradually over- 
 came the distracting effects of the oblique lines, and the 
 illusion disappeared. A second series of photographs taken 
 after the practice series showed that his eye followed the 
 long line with great precision. Photographs with other 
 illusions show clearly the distracting effects of the additional 
 lines as indicated in full in Fig. 46. 
 
 Relation between size and distance. When we study the 
 relation of size to distance from the observer, we find a 
 series of complexities even greater than those which have 
 appeared thus far. In order to demonstrate this experi- 
 mentally an observer should first secure an after-fmage 
 through the steady fi.xation of some bright object. The 
 after-image covers a certain number of retinal elements and 
 may be considered as giving, as long as it lasts, a constant 
 group of sensations. When the observer is looking at the 
 object this mass of sensations will be interpreted as having 
 a certain definite size and distance. When the same mass 
 of impressions comes from the after-image, it can easily be 
 related to different distances, and with each change in ap- 
 parent distance it will take on a different apparent size. 
 The change in distance can easily be produced by looking 
 at various surfaces which are at different distances. The 
 after-image will seem in each case to be on the surface at 
 which the observer is looking at the moment, whatever the 
 distance of that surface. The after-image will seem smaller 
 when the surface on which it is projected is nearer than the 
 original object from which the image was derived, and larger 
 when the surface is farther away. 
 
 Definite optical relation between the distance and the size 
 of an object and the size of the retinal image from this 
 object. This series of observations makes it clear that the 
 size of a retinal image does not determine the interpretation 
 of the size of an object without reference to the additional 
 
COMBINATIONS OF SENSATIONS 
 
 179 
 
 fact of distance. A given retinal image, for the after-image 
 on the retina remained the same throughout the series of 
 observations, may be interpreted as a large object far away 
 or as a small object near at hand. The optical principle 
 which underlies this series of observations is illustrated in 
 Fig. 52. In this figure the retinal image is represented by 
 the inverted arrow AB, and the lines from the extremities 
 of this image passing through the optical center of the lens 
 determine the positions of various external objects, any one 
 of which satisfies the image. It will be seen from this 
 
 Fig. 52. The retinal image AB may be equally well related to any one of 
 
 the objects ad, a'b\ a''b" 
 
 drawing that a succession of arrows outside of the eye, differ- 
 ing in length from each other, may all cast the same retinal 
 image. This general principle is doubtless familiar to every- 
 one when stated in the following simple terms : A small 
 object such as the finger held near the eye can shut out the 
 image of a large remote object, such as a tree or a building. 
 When, now, the after-image in the experiment is projected 
 to distances near and far away, its significance and perceptual 
 interpretation are immediately modified, even though the 
 retinal sensations are uniform in volume and distribution on 
 the sensory surface of the eye. 
 
 Berkeley's statement of the problem of visual depth per- 
 ception. These observations lead us to a problem which was 
 so clearly .stated by one of the early writers in the modern 
 
i8o PSYCHOLOGY 
 
 period of psychology that we may quote his statement in 
 full. In a treatise published in 1709 Bishop Berkeley said: 
 
 It is, I think, agreed by all that distance of itself, and immedi- 
 ately, cannot be seen. For distance being a line directed endwise 
 to the eye, it projects only one point on the fund of the eye — 
 which point remains invariably the same, whether the distance be 
 longer or shorter. I find it also acknowledged that the estimate we 
 make of the distance of objects considerably remote is rather an 
 act of judgment grounded on experience than of sense. 
 
 Berkeley goes forward in the remainder of the ''Essay toward 
 a New Theory of Vision " to account for this process, which 
 he calls a process of judgment. He draws attention to the 
 fact that whenever one looks at an object near at hand he 
 rotates his two eyes toward the nose so that the points of 
 view from which he observes the object are different in the 
 two eyes. He asserts that the convergence of the two eyes, 
 as their inward rotation is called, gives rise to certain experi- 
 ences of movement, which are utilized as interpreting factors. 
 Experiments on binocular vision. The researches of 
 modern experimental psychology have confirmed, in general, 
 Berkeley's explanation, though they emphasize more than 
 he did the differences between the two sets of retinal im- 
 pressions received in the two eyes. The fact that the two 
 eyes contribute a complex of sensations through which we 
 perceive distance has been abundantly confirmed. The 
 reasoning involved is as follows : If distance is recognized 
 as a result of a complex of sensations coming from the two 
 eyes, then it should be possible to show that the recognition 
 of depth is seriously interfered with by the withdrawal of 
 any of the factors contributed by the two eyes. It is not 
 possible to remove altogether the influence of both eyes, 
 even when one is closed ; hence, vision can never be reduced 
 to strictly monocular vision, but the following simple experi- 
 ment may be tried to show the dependence of the clear 
 
COMBINATIONS OF SENSATIONS i8i 
 
 recognition of depth upon vision with two eyes. If an ob- 
 server covers one eye and then attempts to bring his finger 
 directly over some object which stands in front of the open 
 eye, he will find that the ability to bring the finger directly 
 over the object in question is very much less than his ability 
 to do so under the ordinary conditions of binocular vision. 
 A direct observation of the same general fact can be made 
 if the observer will note carefully the difference in the ap- 
 parent solidity and remoteness of objects when he observes 
 them first with a single eye and immediately afterward with 
 both eyes open. These observations show that the complete 
 recognition of distance and depth involves all the sensory 
 factors from the two eyes ; whenever there is any disturbance 
 of the normal conditions the result appears in incomplete 
 perception, for the relational or perceptual process does not 
 in such cases have its normal complex of content with which 
 to deal. 
 
 Difference between the images in the two eyes. The con- 
 tributions made to experience by the two eyes are different, 
 as can be clearly seen if an observer will hold some solid 
 object near the face and look at it, first with one eye open 
 and then with the other. The difference between the two 
 views in the two eyes can be briefly defined by saying that 
 with the right eye one sees more of the right side of a solid 
 object and less of the left side, while with the left eye one 
 sees more of the left side of a solid object and less of the 
 right side. These relations are made clear in Fig. 53. 
 When the two retinal images from the solid object are 
 received by an observer, they are immediately fused with 
 each other into a single perceptual complex, as were the 
 two groups of auditory sensations discussed in an earlier 
 section of this chapter. 
 
 Stereoscopic figures and appearance of solidity. There is 
 an apparatus often used for purposes of amusement, in which 
 the principle that the appearance of solidity depends upon 
 
l82 
 
 PSYCHOLOGY 
 
 disparity of the two retinal images is utilized to produce the 
 appearance of solidity even when no solid object is present. 
 The apparatus in question is the stereoscope. Photographs 
 are taken or drawings are made, corresponding in form to 
 
 the retinal images which 
 would be obtained by two 
 eyes if they were look- 
 ing at a solid figure or 
 series of figures at differ- 
 ent depths. The two 
 drawings or photographs 
 are then projected by 
 means of the stereoscope 
 into the two eyes of an 
 observer in such a way 
 that the right retina is 
 stimulated by the image 
 appropriate to the right 
 eye, and the left retina 
 is stimulated by the fig- 
 ure appropriate to the 
 left eye. The observer, 
 who thus receives the 
 sensory impressions ap- 
 propriate to solidity, will 
 naturally fuse the two 
 images and will see in 
 space before him a solid 
 object which, in reality, 
 is not there, but which 
 is adequately represented by the two flat drawings projected 
 into his eyes. A great many experiments can be tried with 
 the stereoscope which make clear the significance of the 
 two retinal images for the recognition of solidity and depth. 
 It can thus be shown that the fused resultant, that is, the 
 
 Fig. 53. Showing binocular parallax 
 
 The cube BDAC is held near the two eyes 
 with the result that the right eye sees the 
 surface DA and the right side of the cube, 
 while the left eye sees the surface DA and 
 the left side of the cube. If a plane is passed 
 through the rays of light which enter the eye 
 from the cube, as indicated by the dotted line 
 in the figure,, it will be seen that the retinal 
 images of the two eyes contain each a distinct 
 element. The eye on the left-hand side of the 
 figure has a retinal image corresponding to 
 BD^ which is absent in the other eye. Further 
 details will be obvious from the figure 
 
COMBINATIONS OF SENSATIONS 183 
 
 percept of a solid object, does not derive its characteristics 
 from either one of the retinal impressions considered in 
 itself, for each image so considered is deficient in solidity. 
 The fusion is, in a very proper sense of the word, a compro- 
 mise between the two different images, and there appears as 
 a result of fusion at least one characteristic which neither 
 figure had in itself ; namely, the characteristic of clearly 
 defined solidity. 
 
 Retinal rivalry. When the binocular images are totally 
 different, as in certain experiments which may be arranged 
 with the stereoscope, the observer finds that it is impossible 
 for him to fuse the two groups of impressions.- Thus, if he 
 looks with one eye at a series of horizontal lines, and with 
 the other at a series of vertical lines, he will see the fields 
 in succession. The group of sensations coming from one 
 retina will first be recognized in clear consciousness and 
 will then fade out and give place to the sensations derived 
 from the second retina. There is thus an oscillation in 
 experience which is vividly described by the term '' retinal 
 rivalry." In retinal rivalry there is obviously a lack of fusion 
 of the sensations. The artificial differences in binocular 
 images here produced are so foreign to the experiences 
 which present themselves in ordinary life that the observer 
 is unable to fuse them into a single conscious process. If 
 such strange combinations of sensations are to be in any 
 way related, it must be in a temporal succession of mental 
 activities rather than in a single spatial form. 
 
 Factors other than those contributed by the two eyes. 
 The recognition of depth through the fusion of two groups 
 of retinal sensations is not the only form of visual recogni- 
 tion of depth. Other factors of experience and other types 
 of relation may enter into the complex. In every case, how- 
 ever, the factors or relations which contribute to the inter- 
 pretation of solidity are, like the differences in binocular 
 vision just discussed, complexes which get their significance 
 
1 84 PSYCHOLOGY 
 
 and value not because of their sensation qualities but by 
 virtue of the relations into which the sensations are brought. 
 
 Aerial perspective. The first facts to which reference may 
 be made are the differences in colors and sharpness of out- 
 line which appear when objects are seen through different 
 thicknesses of atmosphere. Remote colors are always dull 
 and darker in shade than colors near at hand, and the out- 
 lines of remote objects are ill-defined. We are so trained 
 in the interpretation of these general facts that in looking 
 at a landscape we pay very little attention to color quality or 
 to the lack of clearness in outline, but utilize these immedi- 
 ately for purposes of depth perception ; that is, the sensa- 
 tions are not recognized as distinct facts in experience, but 
 are allowed to serve their function, which is to indicate the 
 position of the object from which they come. Let the ob- 
 server carefully compare his experience of distant fields in 
 the landscape with fields near at hand. He will find that 
 the remoter greens are blue in cast, even though under 
 ordinary circumstances his attention is not directed to these 
 differences in color shades. The same truth is well illus- 
 trated by the fact that persons who have been accustomed 
 to living in a moist atmosphere always misinterpret distances 
 when they go to regions where the air is clear and free from 
 moisture. Great distances seen through clear air are under- 
 estimated because of the small effect which the air produces 
 in modifying the colors and outlines of objects. 
 
 Geometrical perspective and familiarity. Another impor- 
 tant means of recognizing depth is through the familiarity 
 which we have acquired with certain common objects. If a 
 given object is carried farther and farther away from the 
 eye, it will cast upon the retina a smaller and smaller image. 
 If a man first observed at a distance of ten feet moves to 
 a distance of twenty feet, the size of the retinal image and, 
 consequently, the mass of sensations derived from this man 
 will decrease one half. We seldom interpret such changes 
 
COMBINATIONS OF SENSATIONS 185 
 
 in the size of a retinal image of a familiar object as changes 
 in the size of the object itself ; thus, we never say that a 
 receding man has dwarfed to half his original size. We 
 have learned by long experience that most of the objects of 
 our environment are permanent in size and that the changes 
 in our sensations merely indicate changes in the position of 
 these objects. In this way we build up an elaborate series 
 of recognitions of differences in depth. How completely we 
 depend upon this recognition of familiar objects for our 
 interpretation of unfamiliar or undefined experiences will be 
 recognized if it is remembered that the interpretation of the 
 size and distance of objects in photographs is always uncer- 
 tain unless some familiar figure, such as that of a human 
 being, appears as a scale by which to gauge the sizes of the 
 other objects. 
 
 Shadows. Another factor which is sometimes significant 
 in giving rise to the interpretation of depth is found in the 
 shadows cast by objects. The apparent solidity of a bank of 
 clouds in the sky cannot depend upon binocular differences, 
 because the clouds are too remote. They are also quite un- 
 familiar, and may be without color ; therefore the methods 
 of interpretation w^hich we have described up to this point 
 are quite inadequate to explain their apparent solidity. The 
 shadows which they cast upon each other are, however, so 
 clear in their indication of differences of position with refer- 
 ence to the sun that we immediately recognize a bank of 
 shaded clouds as made up of parts differing in distance from 
 .us. The same principle of recognition of solidity is utilized 
 in all flat drawings intended to represent solid objects. Such 
 flat drawings can always be made to suggest solidity with 
 vividness when they are shaded in a way corresponding to 
 the objects themselves. 
 
 Intervening objects. Finally, we make use of the fact that 
 near objects very frequently cut off our vision of remote ob- 
 jects. Thus, if a tree which can be seen in all of its parts 
 
1 86 PSYCHOLOGY 
 
 cuts off a portion of a house or other object, we perceive 
 the house not as divided by the tree but as standing behind 
 it. Here again we interpret our sensations as indicating dif- 
 ferences in position rather than differences in the objects 
 themselves. 
 
 Depth a matter of complex perception. One cannot re- 
 view this series of facts with regard to the visual interpreta- 
 tion of depth without being confirmed in his view that space 
 perception is a process in which sensory factors are related 
 to each other in the most complex manner. No retinal im- 
 pression has its value for mental life fully determined until 
 it is brought into relation with other sensations. 
 
 Relation to movements. As in the case of tactual percepts, 
 so here there is a close relation between visual space and 
 movements. In the first place, movements of the eyes are 
 intimately related in their development to visual recognition 
 of space. When an infant attempts to turn his two eyes on 
 the same point of fixation, his movements are frequently so 
 slow and irregular that they have the appearance, especially 
 in photographs, of cross-eyed movements. Even in adult 
 life it is shown by rapid photographs that the two eyes often 
 move to a point of fixation in such a way that while one eye 
 moves rapidly, the other comes up in an irregular, relatively 
 slow movement. The development of a coordinated move- 
 ment is thus seen to be the product of effort and concentra- 
 tion. That a coordinated movement has been developed at 
 all shows how significant it is for the individual that he 
 should acquire a unitary motor response to the complex of 
 retinal sensations. The unity of response stands, indeed, in 
 sharpest contrast to the complexity of the sensory factors. 
 The organized ability to coordinate the two eyes depends on 
 the development of a system in which each phase of experi- 
 ence, without losing its individual reality, is taken up in the 
 single unitary system. Space and the coordinated system 
 of ocular movements are thus seen to be very intimately 
 
COMBINATIONS OF SENSATIONS 187 
 
 related. The complex of movements has a unity which re- 
 sults from the union of all of the different phases of binocular 
 movement into a single coordinated act. Space is also a 
 system in which every point has a certain character of its 
 own and at the same time has characteristics which attach 
 to it as part of the general system. 
 
 General movements as conditions of fusion of retinal sen- 
 sations. In the second place, the relation of visual space 
 perception to organized behavior becomes clearer when it 
 is noticed that the unity of visual percepts is demanded not 
 only in the coordinations of eye movements but also in the 
 coordinations of all forms of behavior which are guided by 
 vision. If one reaches out his hand to grasp an object, his 
 sensory impressions of the object will be derived from two 
 eyes, but the reaction to be effective must be to all the 
 sensations at once. 
 
 Space a system of relations developed through fusion. 
 Our treatments of space perception in the sphere of touch, 
 hearing, and vision bring us to a general conclusion that 
 space is a closed system built up through the fusion of 
 sensations and, further,- that this system is closely related 
 to bodily movements. 
 
 Movement and mechanical laws. The evidence that 
 there is a close relation between space and bodily move- 
 ment appears in the fact that space as we perceive it ex- 
 presses those mechanical laws which govern all bodily 
 movements. Human central nervous organization and re- 
 lated muscular movements are, from the very nature of 
 mechanical law with which the movements must comply, 
 capable of only a very definite system of developments. 
 One cannot move his hand at the same time toward the left 
 and the right. Left and right come to be, therefore, clearly 
 distinguished directions in the organization of human re- 
 sponses to sensations. One cannot move his hand back- 
 ward and forward in the same movement. As a result, all 
 
1 88 PSYCHOLOGY 
 
 sensations which are to be related to movements are ulti- 
 mately assigned to places either in front or behind, never 
 in both positions at the same time. The child begins life 
 without a thorough organization of his movements and, 
 correspondingly, without any definite spatial forms of per- 
 ception. The two develop together as he actively adjusts 
 himself to the world about him. Finally, as he becomes 
 master of his movements he finds that his perceptual world 
 also has taken on certain definite sequences of arrangement 
 which are so stable and systematic and so harmonious with 
 what he comes to know theoretically of mechanical law that 
 he can study the spatial system as he finds it in his per- 
 ceptual consciousness and relate this spatial form of percep- 
 tion to his science of mechanics without the slightest fear 
 of finding any incongruity in the two groups of facts. It 
 should be noted here again that such a complete system of 
 space is much more than a series of sensations. Sensation 
 qualities are necessary as the factors with which the indi- 
 vidual must deal ; they constitute the material or content of 
 experience, but the spatial form of perception is a product 
 of perceptual fusion. Every sensation is related to every 
 other not because of its quality or intensity but because 
 every sensation must, in the organization of impressions, 
 take its place in a serial system before it can serve any defi- 
 nite function in individual life or have any clearly marked 
 place in consciousness. 
 
 Perception of individual objects. There are many forms 
 of perceptual fusion which supplement the fusions entering 
 into the closed system of space. To the ordinary observer 
 an object recognized through the two senses of taste and 
 smell is so unitary in character that he does not realize that 
 any fusion of discrete sensations has taken place. By a 
 simple experiment one can easily show that the perception 
 of any article of food involves a number of distinct sensa- 
 tions. Let the observer taste of some familiar substance, 
 
COMBINATIONS OF SENSATIONS 189 
 
 such as coffee, and at the same time, by holding the nose, 
 prevent the air from coming into contact with the olfactory 
 organ, and coffee becomes a sweet liquid with little or no 
 flavor ; even castor oil becomes an inoffensive thick oil 
 under like conditions. Why is it that in ordinary expe- 
 rience tastes and odors are united ? It is because, in spite 
 of the separation of the gustatory and olfactory organs, there 
 is a constant demand in life that tastes and odors shall be 
 used together in guiding conduct. The whole inner organi- 
 zation of the individual is such that these different sensory 
 qualities have a joint significance for perception and for 
 behavior. There is a distinction on the qualitative side 
 between tastes on the one hand, and odors on the other, 
 because the sensory organs for the two qualities are differ- 
 ent ; but there is the most intimate perceptual fusion to 
 serve as a guide to conduct. 
 
 There are perceptual fusions in every sphere of sensa- 
 tion quite as compact as those of taste and smell and as 
 various in character as the objects in the world about us. 
 
 Mere coexistence of sensations no explanation of unity 
 in the percepts of objects. The physiological condition of 
 this unity in the perception of single objects is not to be 
 found in the sensory processes themselves, any more than 
 was the physiological condition for the perception of space. 
 The sensory processes derived from things are very differ- 
 ent in type and in the points at which they are received 
 into the central nervous system. The unity of perception 
 is not to be accounted for by the fact that all the sensory 
 excitations are in the brain together, for not all of the sen- 
 sations that are in consciousness at the same time fuse into 
 a single percept. When we recognize a single object we 
 do so by distinguishing it from its surroundings as well as 
 by fusing its various attributes into a single percept. Thus, 
 one recognizes the book he is reading by distinguishing it 
 from his hands and from the bookcase in the background. 
 
cy 
 
 190 PSYCHOLOGY 
 
 Range of fusion determined by practical considerations. 
 
 Again, as in the treatment of the fusion which leads to 
 space perception, we must appeal to the central coordina- 
 tions which are worked out under the stress of practical 
 demands. One fuses sensory factors into the percept of a 
 thing because he can adjust himself to certain aspects of 
 experience in a single act. Thus, one speaks of a book- 
 case and its contents as a single object when he merely 
 wishes to name over the articles of furniture in his room. 
 He distinguishes the separate books as objects when he 
 wishes to take them out and use them. The range of one's 
 experience of a thing is thus seen to depend not on sen- 
 sory processes but on the practical motives which lead to 
 the synthesis of more or less comprehensive groups of 
 these sensations into single phases of experience. 
 
 Changes in percepts through repetition. The fusion of 
 factors into single groups becomes easier after repetition. 
 Thus the expert rifleman comes to recognize at once the 
 movement of his game, the distance of the game from 
 himself, and the wind which will influence his shot, factors 
 which might have coexisted indefinitely without being fused. 
 All this he has acquired as the result of repeated eft^orts to 
 shape his conduct in accordance with the demands of his 
 total environment. Indeed, such a case of acquired fusion of 
 widely divergent sensory factors may very frequently involve 
 in its earliest stages conscious effort to adapt action to whole 
 groups of sensations. The unity is made more and more 
 compact as repeated efforts are undertaken to recognize the 
 factors together, so that ultimately the perceptual unity, which 
 began in a conscious relating of factors, becomes a synthetic 
 unity of the ordinary type ; thus, we learn to see pen and 
 hand and paper together when we learn to write, until all 
 the factors which enter into the act of writing and its con- 
 scious control are unified, and the final consciousness seems 
 very simple, although it is a complex of many factors. 
 
COMBINATIONS OF SENSATIONS 191 
 
 Parallel development of perception and habit. Discus- 
 sions of perceptual fusion might be carried over directly into 
 the discussion of habits so as to show that the development 
 of organized perception and the development of organized 
 activity always go hand in hand. The training of eye and 
 hand in any technical art, of ear and vocal cords in singing 
 or speaking, of ear and hand in playing a musical instru- 
 ment, go together in practical experience. The expert in 
 every line not only acts more skillfully but he sees or hears 
 more skillfully and comprehensively. Perception is discrimi- 
 native and complete just in so far as the factors of experi- 
 ence are organized into wholes appropriate for individual 
 reaction. Our present purposes, how^ever, can be fully satis- 
 fied without a complete study of habits. The perceptual 
 fusion involved in the recognition of an object is one phase 
 of organization ; habit is an expression of this organization 
 and will be taken up in a separate, later chapter. 
 
 Time as a general form of experience. Before leaving 
 the subject of perception it is important that we consider 
 briefly a form of arrangement which has often been re- 
 garded as similar in character to the space form ; namely, 
 time. Time, like space, involves a relation betw^een several 
 factors of experience. Like space, it is not a sensation 
 quality. It is even more general in character than space, 
 for it is not merely a form of perception ; it is also, and 
 indeed chiefly, a form of the indirect, or memory, experi- 
 ences. A percept is always in the time series, but it is 
 always in that portion of the time series which we call 
 ''the present." It will, accordingly, be appropriate for us 
 to discuss in this connection some of the attributes of ''the 
 present," leaving the other phases of time consciousness to 
 be taken up in connection with memory. 
 
 Experimental determination of the scope of '' the 
 present." "The present" is not a single point of experi- 
 ence ; it is a group of experiences. Some experimental 
 
192 PSYCHOLOGY 
 
 evidence as to the possible length of ''the present'' may 
 be gained as follows : Tap rapidly on the table at inter- 
 vals of half a second or less, producing a series of sounds, 
 and find how many taps of this kind can be grouped into 
 a single easily apprehended unity. The observer will have 
 little difficulty in determining the limit of such a series if 
 he will simply listen to the taps and refrain from counting. 
 A short series of five or six taps will leave behind in 
 consciousness a feeling of perfect definiteness and ease of 
 apprehension. If such a series is exactly repeated, or if a 
 second slightly different series is sounded, the observer 
 will be in no doubt as to the likeness or unlikeness of 
 the two series. If, on the other hand, a series of twenty 
 or thirty taps is sounded, the observer will recognize that 
 at a certain point in the series a state of confusion sets in. 
 The series is no longer apprehended as a unity, but has 
 a vaguely defined massiveness which seems to elude the 
 mental grasp. 
 
 Scope of '' the present" and its varying conditions. The 
 ability of the observer to group together a series of experi- 
 ences is radically modified when the series itself is changed. 
 Thus, if every third tap is made stronger than the others, 
 or if it is given a slightly different quality, as in a series 
 of musical notes, the scope of the immediately recognized 
 group will be much increased. If the taps come irregu- 
 larly, either in point of interval or in point of intensity or 
 quality, the scope of the unitary group will be decreased. 
 
 Time relations in verse and related systems of experience. 
 All these facts appear in such practical forms of time per- 
 ception as those which are utilized in making up English 
 verse. The recognition of the successive feet in poetry is 
 facilitated by grouping the sounds into simple compact 
 groups. The character of each group is determined by 
 variations in intensity, quality, and content in such a 
 large number of ways as to satisfy the demand for novelty 
 
COMBINATIONS OF SENSATIONS 193 
 
 in experience, while at the same time retaining very fully 
 the characteristics necessary for temporal uniformity in the 
 successive groups of factors. 
 
 Time arrangement as conditioned by the rhythmical 
 changes in nervous processes. To find a precise physio- 
 logical basis for the time grouping of experience will 
 require the discovery of processes which are much more 
 general than those which constitute the physiological basis 
 for space perception and for general perceptual unity as 
 exhibited in the recognition of objects. Indeed, we must 
 go far enough, as indicated above, to recognize that the 
 conditions of temporal discrimination are involved in indi- 
 rect memory processes even more than in perception. 
 Such a general characteristic is to be found in the fact 
 that all nervous processes are constantly fluctuating in 
 intensity because the inner nervous condition is never 
 in equilibrium. The nervous condition is a living process, 
 now rising to a higher intensity, now declining to a low 
 intensity. This can be seen if an observer will pick out 
 in the constellation Pleiades a faint star which is just 
 visible, and watch it for a time. He will find that it disap- 
 pears and then reappears for an interval, only to disappear 
 again. The rhythmical change is here so complete that 
 it is perceived as a change in the object. A like fluctu- 
 ation of intensity is present in all sensory impressions, 
 even if the sensation is so strong that its decrease in 
 intensity does not cause it to disappear entirely. 
 
 Perception more than the flux of sensations. In addition 
 to the fluctuations in experience which result from the con- 
 ditions in the nervous system, there are changes which arise 
 from the relation of the observer to the object. For example, 
 as one makes his way down the street he sees some object 
 for a moment and then loses sight of it until he comes 
 once more to a point from which he can observe it. In all 
 this flux of experience action must be based on a recognition 
 
194 PSYCHOLOGY 
 
 of the permanency of objects which transcends present 
 sensations. We project our fluctuating sensations into a 
 series which provides for time changes which are not 
 changes in the things themselves. Thus we find new evi- 
 dence that experience is organized out of sensations but 
 goes far beyond sensory quahties and intensities in the 
 attributes which it exhibits. Time is not a sensation ; it 
 is a form in which sensations are held because the mind 
 recognizes in objects a permanency which extends beyond 
 present personal experience. 
 
 SUMMARY 
 
 Discussions of perception. The discussion of perception may 
 be closed with a brief summary. Perception involves, first, a 
 spatial order ; second, the compact fusion of sensations into 
 percepts of separate objects in the world ; and third, the begin- 
 ning of a temporal order. The spatial arrangement is intimately 
 connected with movement, being the arrangement given to sen- 
 sory factors under the mechanical demands for characteristically 
 different reactions to different sensory factors in the total mass 
 of experience. Fusion of sensations into separate recognitions of 
 objects is, like spatial arrangement, related to activity, for all 
 those phases of sensory experience will be fused together which 
 require one and the same response. Finally, time recognition 
 depends on the flux in experience which comes to be recognized 
 as a flux not interfering with the permanency of objects. 
 
CHAPTER IX 
 
 HABITS 
 
 Organic retentiveness. Up to this point only casual ref- 
 erence has been made to the fact that the nervous system 
 is constantly undergoing structural changes as a result of 
 use. When an impulse passes from cell to cell, it leaves 
 behind a path which makes it easier for some new impulse 
 at a later period to pass along the same course. In this way 
 it is also made easier for later impulses to be brought 
 together. Very soon the effects of past experience become 
 so complicated that it is impossible to picture them in 
 detail. Thus, when one learns the name of an object, 
 there must be traced through the nervous system a series 
 of paths which make it possible in all later experience for 
 the percept of that object to arouse the tendency to articu- 
 late the name. Or, to take another type of example, w^hen 
 one has thought of Europe and Asia as parts of a great 
 continental mass, it becomes easier in all future experience 
 to couple these two ideas in thought. 
 
 The facts referred to in the last paragraph are grouped 
 together under such general terms as '' organic memory " or 
 ''retentiveness." It is one of the most important facts about 
 the nervous system that it is highly retentive. As a result 
 of this retentiveness, present action of any part of the 
 nervous system is explicable only in small measure by 
 the impressions of the moment. The present impression 
 is received into a network of paths which carry the im- 
 pulse here and there in accordance with past experiences 
 through traces left behind by such experiences. 
 
 IQ5 
 
196 PSYCHOLOGY 
 
 Remoter conditions of retention. Considered in a large 
 way, all structures of the nervous system are the results of 
 past development. The coordinations which the child in- 
 herits result from racial experiences, and no individual can 
 face the world without reflecting in all of his instinctive 
 attitudes the fundamental experiences of his ancestors. 
 
 Ordinarily we do not think of these remoter effects of 
 experience. We use the terms '' memory '' and '' retention " 
 to refer to those phases of personal experience which we con- 
 sciously connect with our own past contact with things and 
 people. When the ordinary man uses the term '' memory," 
 he thinks of a reinstatement as nearly as possible of some 
 situation experienced at an earlier date. One remembers 
 what he saw and did yesterday. For the psychologist this 
 is only one case of retention and revival. From the doings 
 of yesterday there come over into to-day many influences 
 which are difficult to observe directly. There is skill of 
 hand which is the product of a slow^ and systematic learn- 
 ing process ; there is accuracy of spatial reference which 
 makes it possible for the individual to put his hand with 
 precision on the object before him or at the right or left. 
 There are modes of attention ; there are attitudes of fear 
 and anger, all of which come out of the past development 
 of the individual but are ordinarily not recognized as due 
 to nervous retention. 
 
 Before taking up the cases of memory which are usually 
 recognized as coming under that name, it will be well to 
 study those less noticed forms of organization which bring 
 the past into the present and affect the present without 
 being recognized through introspection. 
 
 Instincts. The simplest cases of this type are the instincts. 
 As was pointed out in an earlier chapter, every individual 
 is born with certain main outlines of his nervous structure 
 provided through inheritance, exactly as the other structures of 
 his body are provided through inheritance. If an individual 
 
HABITS 197 
 
 has arms and legs, he will also have the nerve fibers to 
 connect the muscles of these extremities with the spinal 
 cord. The structure of the sense organs is also provided 
 through inheritance, and, as has been made clear in earlier 
 discussions, there is little or no change in the character of 
 these organs in the course of individual experience. Inherit- 
 ance, however, goes even further than to provide these main 
 structures. The central organs themselves are, to some ex- 
 tent, mapped out at the beginning of individual life. The 
 result of this central organization is that at the time of birth 
 the muscles of the body are not merely under the general 
 control of the nervous system, they are under the control 
 of organized centers which are able, to a certain extent, to 
 coordinate the activities of different parts of the body. 
 
 Protective instincts. Illustrations of instincts occur in 
 the life of any animal and in the early life of human infants. 
 For example, if a young bird hears a loud sound, this sound 
 not only discharges itself through the nervous system, but 
 because of the internal organization of the nervous system 
 the sound will discharge itself into the muscles of the whole 
 body in that form of behavior commonly described as feign- 
 ing death. The individual bird does not recognize the 
 significance or value of its behavior, at least the first time 
 it executes it. The act can therefore not be explained as 
 due in any way to individual intelligence. Furthermore, the 
 same form of action appears in all members of the species. 
 The organization which controls the activity has been worked 
 out in the course of the experience of the bird's ancestors 
 as a form of protective movement to be put into operation 
 whenever the animal is threatened by an approaching enemy. 
 To say that the young bird which performs this movement 
 is cognizant of danger and assumes an appropriate attitude 
 would be to invert the true relations exhibited in the situa- 
 tion. The mode of behavior is immediate and depends 
 directly upon the external stimulation plus the inherited 
 
198 PSYCHOLOGY 
 
 organization. The attitude of fear results from the action 
 
 which takes place without the animal's control or choice. 
 « 
 
 The inner experience of fear is just as much determined 
 through heredity as is the ability to hear the sound through 
 the ear or the ability to tespond to the sound with the 
 muscles of the body. 
 
 Food-taking instinct. Other typical illustrations of organ- 
 ized instinctive modes of behavior may be drawn from a 
 study of the human infant. One of the most fundamental 
 instincts of the infant is the instinct of sucking. Any young 
 mammal responds to a small object placed between its 
 lips by a complex form of reaction which nature has pro- 
 vided as the only possible means of supporting the animal's 
 life during a period when individual experience is not 
 sufficiently mature to guide it in securing its own food. The 
 form of consciousness which accompanies this instinctive 
 behavior is, of course, a matter of speculation, but it seems 
 highly probable that the experience of the infant is one of 
 emotional excitement and of satisfaction when the act finds 
 some appropriate object on which to express itself. 
 
 Instincts established through selection. The process by 
 which the instincts have been evolved is most elaborate. In 
 the later stages of animal evolution those members of a 
 species which do not exhibit the highly organized instincts 
 of protection and food-taking perish. It is easy to see how 
 the instincts are perpetuated through natural selection. In 
 somewhat the same fashion we can imagine how, through 
 a long regressive series, those nervous systems were gradu- 
 ally selected which provided the forms of reaction most 
 favorable to the preservation of life. 
 
 Delayed instincts common. In treating of human instincts 
 the matter is somewhat complicated by the fact that a great 
 many instincts are present only in incipient forms at the 
 beginning of life and are fully matured at a relatively late 
 period. A good illustration of such a delayed instinct is 
 
HABITS 199 
 
 found in the tendency of the young child to walk. That 
 this tendency is inherited is shown by the fact that it will 
 mature, even if there is little or no individual practice. The 
 common development of the young child is a mixture of 
 maturing instincts and ambitious efforts on the part of 
 the child himself and of those surrounding him to hasten 
 the development which would naturally come, even if no 
 exertions were made in that direction. Certain interesting 
 cases are on record which show that children who for one 
 reason or another had never made any individual effort to 
 mature this mode of' activity suddenly exhibited it under 
 suitable conditions in a fully developed form. Young animals 
 have frequently been experimented upon in a way to show 
 that their modes of locomotion are wholly instinctive, even 
 though locomotion develops only at a relatively late period 
 in life. Thus young birds which have been incubated in 
 isolation and have been caged until they reached full 
 maturity will fly with the natural mode of flight of their 
 species as soon as they are liberated. 
 
 Impossibility of distinguishing instincts from later-acquired 
 forms of behavior. As there are instinctive modes of be- 
 havior which develop somewhat slowly during the early years 
 of life, it is impossible to draw a line and say that every 
 form of activity which matures after a certain period is in- 
 dependent of direct hereditary organizations. It is equally 
 impossible to say, on the other hand, that the inherited 
 tracts in the nervous system are in no wise modified in the 
 course of individual experience. Indeed, it is always true 
 that on the foundation of inherited coordinations there is 
 built up a system of refinements and modifications which 
 constitute the characteristic mark of the individual. 
 
 Habits from instincts and from independent conditions. 
 Instincts are sometimes simplified in the course of use ; at 
 other times they are united into larger systems of action or 
 are broken up into their elements and recombined into new 
 
200 PSYCHOLOGY 
 
 types of composite activity. We turn, then, to the consid- 
 eration of these processes of activity which are related to 
 instincts merely as outgrowths and may therefore be treated 
 as the products of individual experience. Those modes of 
 behavior which depend upon individual experience are called 
 habits. In order to make clear the relation of habit to in- 
 stinct, it should be pointed out that not all habits grow 
 directly out of single well-defined instincts. For the pur- 
 poses of our discussion two classes of habits may be dis- 
 tinguished : first, there are habits which develop out of 
 instincts ; second, there are habits which develop by a 
 process of selection from among the diffuse activities which 
 appear whenever there is no definite mode of instinctive 
 behavior which serves as a foundation for development. We 
 may refer to these two types of habits as habits developed 
 from instincts and habits developed from diffusion. 
 
 Development of habit through conflict of instincts. An 
 illustration of a habit developed from instincts is found in 
 the case in which a child develops a certain definite attitude 
 toward certain animals. This attitude of the child can in 
 many cases be shown to have originated out of a conflict be- 
 tween two tendencies. There are two fundamental instinc- 
 tive tendencies in every child, indeed in every young animal. 
 Every young animal tends, on the one hand, to run away 
 from any strange or unusually intense stimulation. A large 
 object moving toward the eyes, a loud sound attacking the 
 auditory organs, or a strange odor or taste will stir up in a 
 young animal a mode of action of the protective type. There 
 is, on the other hand, among all of the higher animals an 
 instinct toward contact with members of the same species 
 and with related forms of animal life. Thus, young birds 
 naturally tend to keep close to any member of their species 
 and to other objects which are in any way similar to mem- 
 bers of their own species. So also do young mammals. 
 Young puppies and young kittens are extremely fond of 
 
HABITS 20 1 
 
 companionship, and even certain of the more soHtary ani- 
 mals naturally herd in packs or in small groups, especially 
 when young. The human infant exhibits both of the two 
 fundamental instinctive tendencies which have just been 
 described. When, accordingly, the child is for the first time 
 confronted by an animal, its reaction may be one of with- 
 drawal or one of friendly contact. Which of the two natural 
 tendencies is actually selected will depend upon a variety of 
 circumstances. If the instinct of flight or protective activity 
 is strong, either because the individual child is disposed to 
 react in this way more emphatically than in the direction of 
 social contact or if the instinct of protection is rendered 
 especially pronounced by some accident of excessive external 
 stimulation at the particular moment, then the instinct of 
 fear will dominate and the social instinct will be suppressed. 
 In such a case the specialized habit will begin to form in 
 the general direction of fear. Sometimes the attitude is so 
 thoroughly determined by the first contact with the animal 
 that all through life the individual tends to follow the initial 
 impulse received at the first experience. There are persons 
 who have a very strong attitude of fear for cats and dogs, 
 which attitude has become a fixed individual habit after 
 being selected from among the various possible instinctive 
 modes of response which existed through inheritance at the 
 beginning of life. 
 
 Nervous development concerned in the selection of in- 
 stincts. The nervous mechanism involved in a habit which 
 has resulted from selection among instincts is relatively easy 
 to explain. We need only to assume that the stimulation 
 which is given at the first experience has two possible lines 
 of discharge, either one of which would be through a well- 
 defined instinctive tract. The conditions of the first en- 
 counter carry the stimulation in question into one of the 
 two instinctive channels, and thereafter this selected channel 
 becomes the natural and easy path of discharge for the 
 
202 PSYCHOLOGY 
 
 stimulus whenever it recurs. The habit is, accordingly, de- 
 pendent upon individual experience only in the one respect 
 that individual experience determines which of the possible 
 instincts shall be selected. 
 
 Habit as a modified instinct. A second somewhat differ- 
 ent type of derivation of habit from instinct is found in cases 
 in which the final mode of activity is not along the line of 
 any single instinct, but is a compromise in which one instinct 
 is modified by conflict with other instinctive tendencies. 
 Suppose, for example, that the human infant who naturally 
 tends to be afraid of an animal is encouraged by circum- 
 stances to assume a friendly attitude toward the animal of 
 which he is naturally afraid. His attitude and mode of re- 
 action may be modified to a greater or less extent, so that 
 instead of expressing the full tendency of his instinct to run 
 away, he may have merely a suppressed internal recoil from 
 the animal, while all of his grosser protective movements 
 are modified. Many of the human instincts are probably 
 thus somewhat reduced in intensitv and in their form of ex- 
 pression. Darwin argued at length that the expressions of 
 human and animal emotions are in many cases simply 
 reduced instinctive forms of behavior. Many of the facial 
 expressions in human beings are, according to his view, 
 remains of early forms of activity in the jaw and mouth 
 muscles, which once accompanied real combat. The changes 
 in circulation and respiration which come with fear and 
 embarrassment are to be regarded as partial expressions of 
 certain fundamental instincts. For example, when we are 
 frightened there is for an instant a pause in all the internal 
 activities preparatory to the violent activities necessary to 
 flight, and after this first pause there comes a rapid beating 
 of the heart which originally accompanied flight. When in 
 mature life one refuses to indulge in flight, he may, never- 
 theless, have all the internal activities. If, however, he 
 persists in refusing to run, the inherited tendency may, 
 
HABITS 203 
 
 through this fact, be gradually overcome even to the point 
 of disappearance. 
 
 Importance of heredity in explaining consciousness. Such 
 examples as these tend to emphasize heredity. The indi- 
 vidual is seen to begin life with a large stock of possible 
 habits and instinctive attitudes. His final attitudes are deter- 
 mined in kind and degree by the circumstances of individual 
 life, but a great number of the fundamental possibilities in 
 human nature are given at the beginning of life. We may 
 say, therefore, that an individual is born with a large stock 
 of attitudes quite as much as with a large supply of organs 
 of sense and forms of possible sensory experience. The in- 
 herited attitudes are not specific in their application until 
 after individual experience has worked out the application, 
 but they are native and explicable only in terms that recog- 
 nize their fundamentally hereditary character. 
 
 Diffusion a mark of lack of organization. Turning now 
 from the habits which are developed through the selection 
 and miodification of instincts, we come to the habits which 
 cannot properly be traced to any single instinct or group of 
 instincts. Let us suppose that a stimulus or a combination 
 of stimulations is introduced into the nervous system^ of the 
 child but finds no specific channel of discharge open to it 
 through inherited organization. This stimulation will pro- 
 duce an excitation which will be very widely distributed 
 throughout the whole nervous system, because it has no 
 specific channel of discharge and because, as free energy, 
 it must be transmitted through the nervous system until it 
 finds a discharge into the active organs. The stimulation 
 will ultimately issue through the avenues of motor dis- 
 charge into the active organs of the body, but instead of 
 issuing in a well-coordinated series it will be distributed 
 diffusely and irregularly and will affect a great number of 
 muscles. An example of the diffuse distribution of stimula- 
 tion in mature life is seen when one is suddenly startled by 
 
204 PSYCHOLOGY 
 
 an unexpected loud noise, and there follows a general con- 
 traction of the muscles throughout the whole body. Such a 
 strong stimulus breaks over all of the bounds of organization 
 in the central nervous system and is distributed diffusely 
 throughout the body. A diffuse distribution of the stimula- 
 tion is clearly a disadvantage to the individual. The state 
 of the organism after the stimulation is such that the indi- 
 vidual is not well adapted to his environment, his activities 
 are not concentrated in any single direction, and he is alto- 
 gether unprepared to meet the future demands which the 
 stimulation may impose upon him. Furthermore, it can 
 easily be observed that the mental attitude which accom- 
 panies such diffuse activity is quite as unorganized as the 
 bodily attitude, and this, also, is an intolerable condition for 
 any individual. The process of modifying such a diffuse 
 reaction, of developing definite and precise attitudes on the 
 mental side and well-coordinated movements on the physical 
 side, is a long, complex process, carried out by the organism 
 and by consciousness with the delays and complications 
 which appear in every process of natural development. 
 
 Development of habit from diffusion. If we take a form 
 of activity which has little or no instinctive background, such 
 as the activity involved in writing, and observe the early 
 stages of the effort to develop this type of activity into a 
 habit, we discover the characteristics of a diffuse activity. 
 It will be found, first, that movement is excessive in both 
 extent and intensity. The child who is learning to write 
 moves not only the necessary muscles of the fingers and 
 hand directly engaged in wTiting, but the muscles of the 
 other hand as well. He also moves the muscles of the face. 
 The diffusion of the excitation throughout the whole organ- 
 ism is one of the most obvious facts to be observed in such 
 a case. In the second place, the elements of movement 
 which are present are not coordinated into harmonious 
 wholes. The various muscular contractions involved in the 
 
HABITS 205 
 
 earliest attempts at writing seldom enter into such relations 
 that there is economy in their several activities. This will 
 be apparent if one observes the way in which the fingers 
 and the hand act during the child's formation of series of 
 letters. There must always be a movement of the hand 
 during writing to carry the fingers across the page. In the 
 child's writing the fingers are used as long as they can be 
 used without any cooperating hand movement. The hand 
 is brought into play only after the fingers have become so 
 cramped that they can no longer make lines. When this 
 cramping of the fingers reaches such a point that it can go 
 no farther, the finger movement is altogether suspended for 
 a moment and the hand is moved forward in a distinct and 
 relatively separate act. The writing then proceeds as before, 
 the fingers being used quite to the exclusion of the hand. 
 This obvious lack of combined activity of the hand and 
 fingers illustrates a general fact which is also exhibited by 
 the incoordination of the learner's several fingers in relation 
 to one another. The thumb and first finger do not at the 
 outset cooperate with each other in the harmonious way in 
 which they should. For example, at the beginning of an 
 upward stroke, as in the written letter /, the first finger 
 presses downward against the pencil or pen more vigorously 
 than is necessary and, as a result, the thumb is called upon 
 to do an excess of work in order to overcome the unneces- 
 sary downward pressure of the first finger. There is thus a 
 lack of harmony and even a certain degree of interference 
 in the organs which are directly involved in the activity. 
 The explanation of diffusion and incoordination at the be- 
 ginning of development is similar to the explanation of the 
 general diffusion of the activity throughout the whole muscu- 
 lar system in the case of a sudden loud noise. In both cases 
 the nervous impulses which excite the muscles do not follow 
 definite channels. In the case now under consideration the 
 channels are not yet developed, while in the case of the loud 
 
2o6 PSYCHOLOGY 
 
 sound they are not able to confine the strong discharge to 
 definite paths. 
 
 Undeveloped movements. Another characteristic of an 
 undeveloped movement is one which is closely related to its 
 incoordination, and consists in the fact that the various phases 
 of movement are all of brief duration, not being united with 
 each other into a continuous series. If one examines the 
 writing of a child, he finds that the lines, instead of being 
 continuous, fluent lines, are made up of short, irregular parts. 
 The direction of the movement in these short, irregular parts 
 is very frequently away from the general direction which the 
 movement should follow. We may say that the movement 
 is a succession of efforts to produce the line rather than a 
 sequence of coordinated muscular contractions appropriate 
 to the general movement. When the movement develops, 
 as it does after practice, the different elements are bound 
 together in such a way that their sequence cannot be detected ; 
 they are no longer separate factors. The adult who begins 
 to write the letter / does not make a series of separate move- 
 ments as the pencil is carried along the upward stroke. He 
 does, however, make a series of muscular contractions. The 
 transition from the irregular succession of separate move- 
 ments to a series of contractions constituting phases of a 
 single complex activity, which, however, is thoroughly uni- 
 fied, results from the coupling together of a series of nervous 
 tracts which provide for the proper temporal distribution of 
 the motor excitation. 
 
 Diffusion analogous to all forms of overproduction. It is 
 clear from the foregoing study of the characteristics of an 
 undeveloped activity that nature approaches this problem of 
 development in the same way in which all the problems of 
 developmicnt are approached ; namely, through excessive pro- 
 ductions and selection of the proper elements. Since the child 
 does not have the proper nervous organization to control 
 ihis movements, nature has provided that he shall make a 
 
HABITS 207 
 
 superabundance of movements involving all of the different 
 parts of the body, even those which are not directly con- 
 cerned in the final activity. If, in this excess of movement, 
 certain factors accomplish the end toward which the indi- 
 vidual is working, these successful constituents of movement 
 will gradually be em.phasized and the unsuccessful constitu- 
 ents will gradually be eliminated, until finally diffusion gives 
 way to a limited number of precise and well-defined combina- 
 tions of activity. If the selected factors are repeated together 
 a sufificient number of times, the nervous activities involved 
 in each particular phase of the movement gradually become 
 connected with each other. 
 
 Conscious correlates of habit. The conscious accompani- 
 ments of action which has grown habitual are easily described. 
 There is a feeling of familiarity when one is trained to respond 
 to sensations ; there is a definiteness of discrimination which 
 makes one's percepts sure and clear. Too often the psychology 
 of habit has been guilty of the statement that habituation leads 
 to unconsciousness. This is not the case. When we can deal 
 skillfully with any situation, we have an attitude of attention 
 and of assurance wholly different from the attitude of indefi- 
 nite excitement which accompanies diffusion. The skillful 
 man is the discerning man ; his discernments may disregard 
 certain factors and emphasize others, but, on the whole, 
 he will give attention to that which is most important in 
 guiding action. 
 
 Instinct, habit, and mental attitudes. The reader will be 
 able without detailed discussion to see the relation of this 
 chapter to the earlier chapter which deals with mental atti- 
 tudes. All mental life exhibits natural likes and dislikes, 
 acquired sympathies and antipathies, forms of attention and 
 interest. These are related, as was shown before, to modes 
 of reaction. We now see how these tastes and interests arc 
 developed as a part of the individual's adjustment of himself 
 to the world. Some tastes are traceable to inherited instincts, 
 
2o8 PSYCHOLOGY 
 
 others to acquired habits, and so on through the Hst. The 
 important fact for psychology is that past experience comes 
 over into the present in the form of fundamental attitudes 
 and tendencies. The introspective observer is likely to make 
 the mistake of thinking that his likes and dislikes are the 
 products of his present thinking, when in reality they come 
 to him from a remote past, even in some cases from his 
 racial inheritances. 
 
 Applications of the doctrine of attitudes to social science. 
 What is shown by these few examples is of the greatest im- 
 portance for the social sciences. Social life has developed 
 innumerable habits in the individual. We pass each other 
 on the right ; we accost our friends on the street ; we gather 
 about the table and take our food in an orderly way. In these 
 and a thousand of the customs of social life we record the 
 experience of the past. At the moment we find ourselves in 
 sympathy with our surroundings. Indeed, we should be most 
 uncomfortable if our surroundings did not call for those forms 
 of behavior which are laid down by habit in our nervous sys- 
 tems. Personal habits and social customs have thus come to 
 be two aspects of a single line of development. Here again 
 we are often too much in the midst of the experience itself 
 to see how our social attitudes came into being and what is 
 their real character. 
 
CHAPTER X 
 
 SPEECH AS A FORM OF BEHAVIOR 
 
 Speech as a highly important special habit. Among the 
 habits developed by human beings none is so elaborate as 
 speech ; none is so intimately related to the higher levels 
 to which human experience attains. Speech is evidently a 
 form of muscular behavior, as can be readily observed if one 
 notes the movements in the thorax, larynx, and mouth dur- 
 ing articulation. So complex, however, are the mental proc- 
 esses related to the movements involved in speech that we 
 ordinarily overlook entirely the physical side of the process 
 and think of speech only as one of the higher forms of 
 mental activity. 
 
 Speech and ideas closely interrelated. There would be 
 logical justification for a postponement of the discussion of 
 speech until after the description and classification of ideas 
 and of those thought processes which develop with the 
 evolution of language. Speech would then be treated, as it 
 is in the thinking of most people, as a product or expression 
 of higher intelligence. But speech is more than a product 
 of thought ; it is the instrument which makes thought pos- 
 sible ; or, differently expressed, it is the kind of reaction 
 which is essential to the higher attitudes of discrimination 
 and comparison. Just as the processes of perception are 
 not merely receptive but involve reactions, so the higher 
 thought processes are active and depend for their character 
 on those forms of behavior which make up the speech habit. 
 We are justified, therefore, in discussing speech before treat- 
 ing of ideas, even though we shall have frequent occasion in 
 
 209 
 
2IO PSYCHOLOGY 
 
 this chapter to refer to the higher mental processes before 
 we have described them in detail. 
 
 Speculations regarding the nature and origin of speech. 
 
 Speech has from the earliest history been recognized by man 
 as a unique power. It is the distinguishing characteristic 
 between Greek and barbarian, between Hebrew and gentile. 
 In more emphatic degree, it is the mark of distinction be- 
 tween man and his nearest relatives in the animal kingdom. 
 
 Long before there was a science of human nature, man 
 speculated curiously as to the source from which language 
 came. His first answer was that the Deity gave it to him 
 by a special act of creation. 
 
 The special creation theory. The special creation theory 
 of the origin of language ignores, however, certain facts 
 which are too obvious to be set aside. It ignores the fact 
 that animals have the ability to make certain vocal sounds 
 which they utilize for purposes of communication with one an- 
 other. We cannot explain how it is that animals have modes 
 of expression so closely related to human language without, 
 at the same time, recognizing the natural origin of language 
 itself. Furthermore, the processes of human expression are 
 constantly undergoing changes and developments which are 
 so natural and so definite in their character that it seems 
 probable that language has always been evolving just as it 
 is at the present time. If the principles under which lan- 
 guage as we know it is developing can be ascertained, it is 
 reasonable to project these laws back of the historical period 
 and to assume that the beginnings of language were also 
 under the regular laws of development. The creation theory 
 has therefore gradually given way to various theories which 
 attempt to give a naturalistic explanation of language. 
 
 The imitation theory. It has sometimes been held in later 
 speculation that language originated from the tendency to 
 imitate sounds. This theory, while it would explain certain 
 of the special forms of words, cannot give any adequate 
 
SPEECH AS A FORM OF BEHAVIOR 21 1 
 
 account of the way in which an individual develops the power 
 of turning imitation to the special ends of speech. There 
 are a number of different animals that are capable of a wide 
 range of imitation, but they have never developed a lan- 
 guage, as has man. This is clear evidence that the essence 
 of language is not to be found in imitation, but rather in the 
 use to which the imitative power is put. 
 
 The interjection theory. It has also been suggested that 
 language developed out of the interjections which man natu- 
 rally used in his most primitive stage of development. If 
 he was astonished by any sudden stimulation, he naturally 
 gave forth ejaculations in response to the sudden excitation. 
 These ejaculations, it is said, came gradually to have the 
 power of calling to mind the situations to which they be- 
 longed and ultimately became the means of communication. 
 Here again the objection to the theory is not that it seems 
 improbable that man began with simple forms of expres- 
 sion, but that the theory does not explain how these simple 
 forms of expression acquired a meaning and importance 
 which they did not have at the beginning. What is needed, 
 rather than a formal description of the first expressions used 
 by primitive man, is a consistent psychological explanation of 
 how the ejaculations came to have significance for mental life 
 and to serve as the vehicles for elaborate thought processes. 
 
 Roots of language in natural emotional expressions and 
 their imitation. The psychological explanation of language 
 begins with a general reference to the statements made in 
 earlier chapters. Every sensory stimulation arouses some 
 form of bodily activity. The muscles of the organs of cir- 
 culation and the muscles of the limbs, as well as other 
 internal and external muscles, are constantly engaged in 
 making responses to external stimuli. Among the muscles 
 of the body which with the others are involved in expres- 
 sive activities are the muscles which control the organs of 
 respiration. There can be no stimulation of any kind which 
 
212 PSYCHOLOGY 
 
 does not affect more or less the character of the movements 
 of inspiration and expiration. In making these general state- 
 ments, we find no necessity for distinguishing between the 
 animals and man ; so far as the general facts of relation 
 between sensations and expression are concerned, they have 
 like characteristics. That an air-breathing animal should pro- 
 duce sounds through irregularities in its respiratory move- 
 ments when it is excited by an external stimulus, especially 
 if that stimulus is violent, is quite as natural as that its hair 
 should rise when it is afraid or that its muscles should 
 tremble when it is aroused to anger or to flight. 
 
 Imitation. The important step in the development of lan- 
 guage is the acquirement of the ability to use the movements 
 of the vocal cords for purposes other than those of individ- 
 ual emotional expression. The acquirement of this ability is 
 a matter of long evolution and depends in its first stages 
 upon social imitation. The importance of imitation in affect- 
 ing the character of animal behavior appears as soon as ani- 
 mals begin to live in packs or herds or other social groups. 
 
 Other imitative communications of animals and man. So 
 far as communication through imitation is concerned, there 
 is no reason why attention should be confined exclusively to 
 the forms of activity which result in sounds. All animals 
 imitate the activities of other members of their species on a 
 very large scale. The stampede of a herd of cattle is an ex- 
 cellent illustration of the importance of the tendency toward 
 imitation. The frightened animal which starts the stampede 
 does not consciously purpose to communicate its fright to 
 the other members of the herd ; it is performing a natural 
 act of its individual life. Incidentally, it affects all those 
 about it by arousing in them a violent form of imitative 
 activity. The stampeding herd may have no consciousness 
 whatever of the original cause of fear in one of its mem- 
 bers ; the real cause of the stampede and of the resulting 
 excitement in the herd is the example of the one frightened 
 
SPEECH AS A FORM OF BEHAVIOR 213 
 
 animal. Thus we see that the activity of an animal takes on, 
 because of the reaction of its social environment, a signifi- 
 cance which the original act never could have had unless it 
 had been imitated. 
 
 Value of sounds as means of social communication. What 
 is true of activity in general is true of activities which result 
 in sounds. The sound produced by the activities of the vocal 
 cords can impress itself readily upon the ears of some other 
 animal, more readily by far than the visual impression of 
 trembling or of general muscular tension. If, now, the ani- 
 mal which hears the sound has itself produced this sound 
 or one closely resembling it in quality and intensity, there 
 will be a natural tendency for the sound stimulation to arouse 
 in the second animal a sympathetic response. Witness the 
 tendency of all the dogs in a community to bark together 
 or of all the roosters to begin crowing together when one 
 gives the signal. The result of imitating the sound will be 
 to throw the imitating animal into an emotional state very 
 similar to that of the animal which first made the noise. 
 This result will be more likely to follow if the two animals 
 are closely related in their organization and types of activity. 
 There will be ^'datively less tendency to sympathize with an 
 animal of entirely different organization and habits, for the 
 activity aroused through imitation in the listening animal 
 will not agree in character with the activity of the animal 
 which sets the example. Thus, one can judge from his own 
 experience that there is very little possibility of arousing in 
 a human being the mental state which appears in dogs or 
 cats through imitation of the sounds which they produce. 
 In general, imitation of sound is valuable as a means of 
 arousing sympathy only between animals sufficiently related 
 to each other to have similar modes of producing sound. 
 
 Limitation of forms of animal communication. Given the 
 similarity of organization which makes imitated sounds sig- 
 nificant, we have a type of communication provided which 
 
214 PSYCHOLOGY 
 
 is widely utilized in the animal world. The food calls and 
 the danger signals of birds are significant to other members 
 of the flock. Such calls have definite natural relations to the 
 organized responses of all members of the species. It is to 
 be noted that these calls do not constitute a language in the 
 sense in which human sounds constitute a language, for the 
 bird calls are incapable of conveying definite ideas, such as 
 ideas of the kind of food or the particular kind of danger dis- 
 covered by the animal which makes the sound. The sounds 
 serve merely to arouse certain attitudes. An animal can 
 induce in its fellows a tendency to fear and flight by means 
 of cries which in the history of each member of the flock have 
 been associated with fear, but the animal can go no farther in 
 its communications than to arouse emotional attitudes. 
 
 The first stages of human articulation like animal cries. 
 There are stages of human infancy which are closely re- 
 lated to the stages of animal life thus far described. The 
 human infant does not at first make sounds as the result of 
 any conscious desire to communicate its feelings to those 
 about it, much less does it use its sounds for verbal dis- 
 cussion of the details of its conscious experiences. The 
 infant makes noises exactly as it swings its arms and legs, 
 because the muscular contractions which produce these 
 noises are instinctive motor expressions related through 
 heredity to the stimuli which arouse them. Later there 
 appears a strong tendency to imitate others of its own kind, 
 and this imitation may serve to put the infant in some con- 
 tact with its social environment and give it a medium of 
 communication comparable in character to that which we 
 find in animals. This is not language, however, for imitation 
 alone is not enough to develop language. Further processes 
 must take place before the full development is effected. 
 
 Articulations selected from the sum of possible activities. 
 While imitation applies to many different forms of activity, 
 such as those of the limbs or face, a moment's consideration 
 
SPEECH AS A FORM OF BEHAVIOR 215 
 
 will make it clear that the activities which produce sounds 
 have a number of unique advantages as vehicles of imitative 
 communication. The ability to produce sounds depends 
 largely upon the animal itself and very little upon external 
 conditions. Contrast sound with visual impressions. Visual 
 impressions are cut off in the dark ; they are cut off by 
 intervening objects and by a turning of the head of the 
 observer. Sounds travel wherever there is air ; they are as 
 easy to produce in the darkness as in daylight ; they can 
 easily be varied in intensity. For these reasons they come 
 to be the chief means of social communication, even among 
 the animals. The result is that the vocal cords and the 
 ability to discriminate sounds are highly developed long 
 before the development of language proper. 
 
 Evolution of ideas and speech. The advance which human 
 language makes beyond animal communication consists in 
 the fact that human language relates sounds to ideas as 
 well as to emotional attitudes. This step cannot be taken 
 until ideas are present in the minds of both parties to the 
 communication. We find ourselves, therefore, at this point 
 involved in a perplexing circle. Human mental processes 
 as we know them are intimately related to language. Even 
 when we think about our own most direct experiences, we 
 use words. Yet these words are not explicable except when 
 we assume complex ideational processes as the necessary 
 conditions for their development and interpretation. Did 
 human mental advance result from the development of 
 language, or did language result from the development of 
 ideas ? The only answer to this question is that language and 
 ideational processes developed together and are necessary to 
 each other. 
 
 In describing the first stages of the development of true 
 language we may assume, therefore, that both speaker and 
 auditor have reached a stage of development where it is 
 possible to have higher nervous and conscious processes. 
 
2i6 PSYCHOLOGY 
 
 Such higher processes are to be contrasted with mere emo- 
 tional attitudes. For example, if one sees his fellow being 
 pointing in a certain direction, there is a strong tendency 
 to turn and look in the same direction. There will result 
 in this case not an emotion but a common attention to some 
 object. The gesture of pointing is, accordingly, a mode of 
 communication which rises to a higher level than does the 
 cry of fear or the food call. Its development opens the way 
 for a higher system of communication. 
 
 Gestures and broad scope of attention. Still higher is 
 the gesture that depicts some elaborate act. Thus, when a 
 man is hungry he will point to his mouth and make the 
 gesture of taking up food and carrying it to his mouth. 
 This simple gesture will not be made by an animal, because 
 the animal has only a limited range of attention. If the 
 animal thinks of food, it cannot entertain any other ideas. 
 It spends all its mental energy seeking food rather than 
 trying to communicate with some other animal. In human 
 life there is breadth of attention exhibited in a gesture. 
 The person who makes a gesture includes in his experience 
 the person with whom he wishes to communicate, plus the 
 idea which is to be communicated. The animal m.ay have 
 a simple idea but not the complex of ideas involved even 
 in gesture. 
 
 This ability of man to have two centers of attention can 
 be explained anatomically by recalling that man has great 
 masses of cerebral tissue within which impulses can be 
 worked over. The animal has only a little brain tissue, and 
 any impulse received in the brain must be discharged very 
 soon in the form of a motor impulse. The hungry animal 
 must act at once in the effort to remove hunger. Man, on 
 the other hand, has enough brain tissue to hold the impulse 
 in suspense, unite it with impressions from his fellow beings, 
 and act in a complex way with full regard both to his fellow 
 beings and to his hunger. 
 
SPEECH AS A FORM OF BEHAVIOR 217 
 
 Gesture, or gesture language as it is called, is thus seen 
 to be not merely a complex form of behavior but one which 
 expresses a new type of relationship between the reactor 
 and his environment. Gesture is a social form of behavior 
 involving attention to persons as well as to objects. Indeed, 
 gesture supersedes the more direct forms of attack on objects. 
 
 Evolution of gestures in direction of simplification. The 
 earliest forms of social communications undoubtedly included 
 much gesture if, indeed, they were not limited altogether 
 to gesture. The term ''natural sign" has been used in 
 describing these early gestures. The gesture was so full 
 and pantomimic in character that the interpretation was 
 almost as direct as in the case of an emotional expression. 
 The gesture could be interpreted by anyone who had passed 
 through an experience at all like that of the person making 
 the gesture. All that we need to assume by way of explanation 
 of gesture is the law of social imitation which was stated in 
 earlier paragraphs and the higher power of reviving ideas. 
 
 The later development .of gesture language brought with 
 it a reduction of the gesture so that it became a mere rem- 
 nant of the earlier act. This reduction to a simpler act was 
 possible within the group of those who had learned to com- 
 municate with each other. Thus, instead of requiring the 
 full pantomime to communicate the fact that one was hungry, 
 it came to be enough that one pointed in the direction of the 
 mouth. A mere clue served to arouse the idea. This stage 
 is reached when both the parties to the communication have 
 developed the power of supplying the ideas needed for 
 interpretation to such a high level that it is very easy to 
 call out the idea by the slightest hint. 
 
 Speech a highly specialized mode of behavior. This de- 
 velopment, which made it less and less important that the 
 gesture be a full pantomime, opened the way for a selection 
 of certain particular forms of activity which became the 
 vehicles of communication and were wholly set aside for 
 
21 8 PSYCHOLOGY 
 
 that purpose. The vocal cords were not available as organs 
 for communication of ideas so long as the ideas had to be 
 depicted in full by means of elaborately imitable gestures. 
 But as the need of gestures diminished and the power of 
 supplying ideas increased, the vocal cords proved increas- 
 ingly useful as special organs of social communication just 
 because they were not otherwise used. The hands which 
 were used for communication during the period when ges- 
 ture was evolving were in demand for the direct practical 
 activities of life. When two individuals wish to communi- 
 cate with each other, it is often extremely inconvenient to 
 suspend all other activity, to lay down what one may be 
 carrying, to come where one may be clearly seen, for the 
 purpose of holding a parley. The vocal cords, on the other 
 hand, are not required for the practical purposes of life. 
 They are easily disconnected in their action from the gen- 
 eral mass of the muscles and, therefore, very naturally 
 became the organs for a system of social activities. 
 
 One of the most primitive forms of vocal art is the 
 work song. This illustrates strikingly the relation of vocal 
 reactions to handwork. The workers secured social coopera- 
 tion through the song, their hands in the meantime being 
 occupied in practical work. 
 
 Consequences of specialization. The fact that speech thus 
 separates itself from other forms of bodily activity and be- 
 comes a highly specialized system of behavior brings with 
 it a number of important consequences. First, it is possible 
 for speech to develop to a high level without involving 
 the corresponding development of any of the practical arts. 
 What is sometimes called pure verbalism may result. Thus 
 a student may acquire mere words and not have any power 
 of applying the words which he repeats to other forms of 
 behavior. 
 
 Second, the specialized character of speech results in 
 the sharp differentiation of one local language from that 
 
SPEECH AS A FORM OF BEHAVIOR 219 
 
 of other sections. Ultimately each language grows so far 
 from the parent root that it is wholly unintelligible except 
 to those who are trained in its special forms. 
 
 Third, there is a possibility that ideas will be attached 
 to sounds so loosely and ambiguously that the two parties 
 to communication will drift far apart in their interpretations 
 while using one and the same sounds. 
 
 Speech an indirect form of behavior. Speech as a form 
 of behavior thus lacks that direct relation to the outer 
 world which most habits exhibit. It takes on a highly 
 artificial character. Its uses are controlled by social con- 
 vention rather than by natural necessity. We may therefore 
 very properly describe speech as an indirect, conventional 
 form of behavior. 
 
 Evolution of writing. The stages of evolution of speech 
 which have been described in the foregoing paragraphs 
 are exemplified in essentially the same sequence, though in 
 slightly different form, in the evolution of the art of writing. 
 
 Writing at first direct in form. The earliest stages of 
 writing were those in which pictographic forms were used ; 
 that is, a direct picture was draw^n upon the writing surface, 
 reproducing as nearly as possible the kind of impression 
 made upon the observer by the object itself (see Fig. 54). 
 To be sure, the drawing used to represent the object was 
 not an exact reproduction or full copy of the object, but it 
 was a fairly direct image. The visual image was thus 
 aroused by a direct appeal to the eye. Anyone could read 
 a document written in this pictographic form if he had 
 ever seen the objects to which the pictures referred. There 
 was no special relation between the pictures or visual forms 
 at this stage of development and the sounds used in articu- 
 late language. Concrete examples of such writing are seen 
 in early monuments, where the moon is represented by 
 the crescent, a king by the drawing of a man wearing a 
 crown. An example of this stage of writing is also supplied 
 
220 
 
 PSYCHOLOGY 
 
 by the ancient Chinese forms shown in the upper Hne 
 of Fig. 55. 
 
 Images reduced to lowest terms as powers of reader 
 increase. The next stage of development in writing began 
 when the pictographic forms were reduced in complexity 
 to the simplest possible lines. The reduction of the picture 
 to a few sketchy lines depended upon the growing ability of 
 the reader to contribute the necessary interpretation. All 
 that was needed in the figure was something which would 
 
 Fig. 54. An Ojibwa love letter, recorded and explained by Garrick Mallery 
 in the Annual Report of the Bureau of Ethnology, 1 888-1 889, p. 363 
 
 The writer, a girl of the Bear totem, b^ summons her lover, who belongs to the 
 Mud Puppy totem, d^ along the various trails indicated, to the lodge, ^, from which 
 the beckoning hand protrudes. The inclosed figures at /,/, and k are lakes. ^ The 
 crosses indicate that the girl and her companions are Christians. " The clear indi- 
 cations of locality," writes Mallery, " serve as well as if in a city a young woman had 
 sent an invitation to her young man to call at a certain street and number " 
 
 suggest the idea to the reader's mind. The simplification 
 of the written forms is attained very early, as is seen even 
 in the figures which are used by savage tribes. Thus, to 
 represent the number of an enemy's army, it is not neces- 
 sary to draw full figures of the forms of the enemy ; it is 
 enough if single straight lines are drawn with some brief 
 indication, perhaps at the beginning of the series of lines, 
 to show that these stand each for an individual enemy. 
 This simplification of the drawing leaves the written sym- 
 bol with very much larger possibilities of entering into 
 
SPEECH AS A FORM OF BEHAVIOR 221 
 
 new relations in the mind of the reader. Instead, now, of 
 being a specific drawing related to a specific object, it 
 invites by its simple character a number of different inter- 
 pretations. A straight line, for example, can represent 
 not only the number of an enemy's army, but it can rep- 
 resent also the number of sheep in a flock, or the number 
 of tents in a village, or anything else which is capable of 
 enumeration. The use of a straight line for these various 
 purposes stimulates new mental developments. This is 
 shown by the fact that the development of the idea of the 
 
 N ^ H * * 
 
 Fig. 55. Ancient and modern Chinese writing 
 
 The upper Hne shows ancient forms of Chinese writing ; the lower Hne shows the 
 
 derived modern forms. Reading from left to right, the characters signify "sun," 
 
 "moon," "mountain," "tree" (or "wood"), "dog" 
 
 number relation, as distinguished from the mass of possible 
 relations in which an object may stand, is greatly facilitated 
 by this general written symbol for numbers. The intimate 
 relation between the development of ideas on the one hand 
 and the development of symbols on the other is here very 
 strikingly illustrated. The drawing becomes more useful 
 because it is associated with more elaborate ideas, while the 
 ideas develop because they find in the drawing a definite 
 content which helps to mark and give separate character to 
 the idea. Striking examples of the simplification of form 
 in order to facilitate the writing of symbols are shown in 
 Figs. 55 and 56. 
 
222 PSYCHOLOGY 
 
 Written symbols and their relation to sounds. As soon 
 
 as the drawing began to lose its significance as a direct 
 perceptual reproduction of the object and took on new 
 and broader meanings through the associations which at- 
 tached to it, the written form became a symbol rather 
 than a direct appeal to visual memory. As a symbol it 
 stood for something which, in itself, it was not. The way 
 
 MM 
 
 Fig. 56. Derivation of the Roman letter M from the ancient Egyptian 
 
 hieroglyphic owl 
 
 The four forms in the upper part of the figure are Egyptian forms. The first on the 
 left is the usual hieroglyphic picture of the owl, or, as it was called in the Egyptian 
 language, mulak. The three remaining upper forms are found in the writings of the 
 Egyptian priests. The first form on the left of the lower series is an ancient Semitic 
 form. Then follow in order an ancient Greek form and two later Greek forms. 
 (From I. Taylor's "The Alphabet," pp. 9, 10) 
 
 was thus opened for the written symbol to enter into rela- 
 tion with oral speech, which is also a form of symbolism 
 (see Fig. 56). Articulate sounds are simplified forms of 
 experience capable through association wdth ideas of ex- 
 pressing meanings not directly related to the sounds them- 
 selves. When the written symbol began to be related to the 
 sound symbol, there was at first a loose and irregular relation 
 between them. The Egyptians seem to have established 
 
SPEECH AS A FORM OF BEHAVIOR 223 
 
 such relations to some extent. They wrote at times with 
 pictures standing for sounds as we now write in rebus puz- 
 zles. In such puzzles the picture of an object is intended to 
 call up in the mind of the reader not the special group of 
 ideas appropriate to the object represented in the picture 
 but rather the sound which serves as the name of this object. 
 When the sound is once suggested to the reader, he is sup- 
 posed to attend to that and to connect with it certain other 
 associations appropriate to the sound. To take a modern 
 illustration, we may, for example, use the picture of the eye 
 to stand for the first personal pronoun. The relationship 
 between the picture and the idea for which it is used is 
 in this case through the sound of the name of the object 
 depicted. That the early alphabets are of this type of 
 rebus pictures appears in their names. The first three 
 letters of the Hebrew alphabet, for example, are named, 
 respectively, aleph, which means ''ox," beth, which means 
 ''house," 2Xidi gimmel, which means "camel." 
 
 The alphabet. The complete development of a sound 
 alphabet from this type of rebus writing required, doubt- 
 less, much experimentation on the part of the nations 
 which succeeded in establishing the association. The Phoe- 
 nicians have generally been credited with the invention of 
 the forms and relations which we now use. Their contri- 
 bution to civilization cannot be overestimated. It consisted 
 not in the presentation of new material or content to con- 
 scious experience but rather in bringing together by asso- 
 ciation groups of contents which, in their new relation, 
 transformed the whole process of thought and expression. 
 They associated visual and auditory content and gave to 
 the visual factors a meaning which originally attached to 
 the sound. Pictures thus came to mean sounds rather than 
 objects (see Fig. 56). 
 
 Social motives essential to the development of language. 
 The ideational interpretations which appear in developed 
 
224 ' PSYCHOLOGY 
 
 language could never have reached the elaborate form 
 which they have at present if there had not been social 
 cooperation. The tendency of the individual when left to 
 himself is to drop back into the direct adjustments which 
 are appropriate to his own life. He might possibly develop 
 articulation to a certain extent for his own sake, but the 
 chief impulse to the development of language comes 
 through intercourse with others. As we have seen, the 
 development of the simplest forms of communication, as 
 in animals, is a matter of social imitation. Writing is also 
 an outgrowth of social relations. It is extremely doubtful 
 whether even the child of civilized parents would ever have 
 any sufficient motive for the development of writing if it 
 were not for the social encouragement which he receives. 
 
 Social system as source of the form of words. Further- 
 more, we depend upon our social relations not merely for 
 the incentives to the development of language but also for 
 the particular forms which oral and written language shall 
 take. It is much more convenient for a child born into a 
 civilized community to adapt himself to the complex symbol- 
 ism which he finds in the possession of his elders than to 
 develop anything of the sort for himself. It is true that 
 tendencies exist early in life toward the development of 
 individual forms of expression. A child frequently uses a 
 certain sound in a connection which cannot be explained 
 by reference to social usage. It may be a purely individual 
 combination, or a crude effort to adopt something which 
 has been suggested by the environment. This tendency to 
 give sounds a meaning might prove sufficient to work out 
 a kind of language, even if the individual were entirely 
 isolated from his fellows ; but the natural tendencies are 
 very early superseded by the stronger tendencies of social 
 imitation, and in the end the social system completely 
 dominates individual development, dictating in all cases the 
 forms of words. 
 
SPEECH AS A FORM OF BEHAVIOR 225 
 
 Social usage and the domination of individual thought. 
 
 In adopting the forms of expression used by those about 
 us, we are led to take up certain general social forms of 
 thought which ultimately control the whole mental life. The 
 effect of this social influence is so far-reaching that it is 
 quite proper to say that an individual is, in a very large 
 measure, the creation of his social relations, at least in the 
 higher phases of his mental life. The fundamental forms 
 of direct activity, which constitute the personal habits by 
 which we have succeeded in adapting ourselves to the 
 demands of the physical world, are to a certain extent 
 unsocial. They are, to be sure, alike in different individuals 
 because they have grown up, as was shown in our earlier 
 discussion, under the demands of a common physical 
 environment. Our forms of space perception, for example, 
 are not the creations of our own individual caprice but 
 rather the arrangement whicK we have given our sensory 
 experiences in our effort to fit ourselves to a world which 
 dictates these space relations to us. Since we have all grown 
 up in the same space world, our space ideas are alike. 
 The community of social ideas expressed in language is of 
 a different type. Even the direct, relatively unsocial forms 
 of perception are influenced by these higher social forms 
 of thought. If, for example, there is no word in a certain 
 social environment for long spatial distances except a word 
 which refers to a certain number of days' journeys, it is not 
 likely that the individual will feel any tendency to discrimi- 
 nate fifteen miles from seventeen. His attitude in this 
 matter will be determined by the attitude of his social 
 environment, and he will neglect in his thought, as do 
 those about him, the finer details of distance. Similarly, if 
 there are no names for certain forms of property rights, it 
 is not likely that the individual will, of his own initiative, 
 recognize these forms of right as belonging to those who 
 constitute the social group with him. 
 
226 , PSYCHOLOGY 
 
 Social ideas dominate individual life. The history of 
 thought has been, in large measure, the history of the 
 development of certain social ideas which could be marked 
 with definite names and made subjects of thought, because 
 they were so marked. Consider for a moment the difficul- 
 ties which would be experienced in conducting any train 
 of thought with regard to the forces of physical nature if 
 there were no names for the different forces and no fully 
 developed definitions to give each name clearly recognized 
 character. If it is true in a general way that general ten- 
 dencies of thought have been dependent upon the develop- 
 ment of words to express ideas, it is still more true in the 
 case of the individual that his mental tendencies are very 
 largely determined by the forms of social thought expressed 
 in words. A child who has had his attention called to 
 certain colors and who is, at the same timxC, given a name 
 for these colors is more likely to identify them in later 
 experience than if no name had been given. The name 
 serves as an incentive to the concentration of attention 
 upon a particular phase of experience which would otherwise 
 be lost in the general mass of sensations. Without the 
 word the possibility of dwelling upon the single phase of 
 experience in thought would be small. This is the reason 
 why the retention of facts in memory is so closely related 
 to the naming of objects. 
 
 Experimental evidence of importance of words. Some 
 experimental evidence can be adduced to show that names 
 are of great importance in this respect. If one is confronted 
 with a large number of pieces of gray paper ranging from 
 black to white, and is asked to discriminate as many of 
 these different grays as he is able to recognize with certainty, 
 it will be found that he can distinguish ordinarily about five 
 classes of gray shades. He can distinguish the very dark 
 from those which are medium dark, the very light from 
 those that are medium light, and he can place between the 
 
SPEECH AS A FORM OF BEHAVIOR 227 
 
 dark and the light grays a middle shade which he is not 
 disposed to classify as either light or dark. Beyond this 
 fivefold discrimination he will find that he is very uncertain. 
 If, now, after making this test under ordinary conditions, 
 the individual is allowed to examine the various shades of 
 gray and to adopt a series of names or numbers for them, 
 it will be found that he can notably increase the range 
 and certainty of his discrimination. The names furnish, as 
 stated above, definite means of concentrating attention upon 
 slight differences which existed from the first but were not 
 noted in experience. Furthermore, when these slight differ- 
 ences have been discriminated and marked by the attachment 
 to them of definite names, they become permanent additions 
 to the individual's equipment and can be retained more easily 
 than they could be as mere unnamed sensation qualities. 
 
 Number terminology as a device for recording posses- 
 sions. One of the best illustrations of the significance for 
 mental life of the creation of a terminology is found in the 
 ease with which a developed individual uses numbers. In 
 general, it may be said that primitive languages have only 
 a very meager number terminology. Savage tribes have 
 frequently been known to have no number terminology 
 reaching above ten, and in some cases tribes have been 
 reported with a number terminology not reaching beyond 
 three. There are certain forms of direct perceptual experi- 
 ence which can be utilized up to a certain point instead of 
 the developed number system which we now have. If a 
 herdsman has a herd of cattle for a period long enough to 
 become acquainted with its individual members, he can 
 recognize the size of the herd by recalling the individuals 
 which make it up. If one has material possessions which 
 can be heaped together, he will come to estimate his wealth 
 directly through the general impression made upon him by 
 collecting all of his wealth at a single point. As soon as 
 the direct recollection of each individual possession came, 
 
228 PSYCHOLOGY 
 
 in the development of human wealth, to be too cumbersome 
 a form of representation, and the collective image became 
 too vague to be relied upon, man naturally endeavored to 
 devise a method of recording his property and retaining it 
 in consciousness in some simplified form. Instead of trying 
 to remember every one of his possessions, he adopted some 
 system of tally. At first he began counting off on his 
 fingers each different article which he wished later to be 
 able to recognize, or he adopted in some cases one of the 
 more elaborate methods found among savages who use 
 pebbles or shells. The Latin root which appears in our 
 word ''calculate" and all related words is the word for 
 pebble, and indicates that the early forms of computation 
 among the Romans consisted in the use of pebbles. 
 
 Symbols for groups of tallies. As soon as the system of 
 enumeration became complex, there naturally arose the 
 necessity for grouping the tallies so that they could be 
 easily surveyed. The method of grouping the tally marks 
 in a system convenient for recognition is suggested by the 
 five fingers on the hand, and this is often adopted, even by 
 savage peoples. A clear indication that this grouping ap- 
 peared in the natural tally systems can be seen in the symbols 
 used by the Romans to indicate numbers, for in this system 
 the number five and the number ten are crucial points in 
 the notation, and show the adoption of a new group symbol 
 to include many individual symbols in a more compact form. 
 
 Parallel growth of number names and system of ideas. 
 As the number system was worked out into a system of 
 major and minor groups there was a tendency to develop 
 a system of articulation directly related to the tally system. 
 Number of the primitive tally form probably developed just 
 as did writing, without reference to speech. The creation 
 of words which should express number was slow, as indi- 
 cated by reference to savage language, because in this case 
 the symbolical system needed to develop to a high degree 
 
SPEECH AS A FORM OF BEHAVIOR 229 
 
 before the demand for corresponding articulation was felt. 
 As soon as the demand for articulation became sufficiently 
 pressing, the words appeared, and they show distinctly in 
 their character the tendency toward groups. Further than 
 this, the names for successive tallies came to be the means, 
 not only of referring to individual marks but also of refer- 
 ring to the serial arrangement of these marks. Thus, the 
 names ''one," ''two," "three," etc. are not significant 
 merely as names of tally marks ; they have also each its 
 special significance as the name of a special position in 
 the total series. 
 
 Development of arithmetic depends on an appropriate 
 system of numerals. The advantage to the child who finds 
 a complete number terminology developed is very great. 
 The more perfect this terminology for purposes of express- 
 ing quantitative relations, the more complete and rapid will 
 be his initiation into the forms of thought which the 
 terminology expresses. The historical illustration of this 
 fact is to be found in the acceptance by European nations 
 of a system of notation which was imported from the East 
 in the Renaissance period. The written number symbols 
 which had been used by the Romans were crude and 
 rendered any forms of arithmetical manipulation extremely 
 difficult. The Arabic system was so much more complete 
 and economical that it immediately took the place of the 
 older and cruder symbolism. How long it would take an 
 individual child to acquire independently anything like the 
 mathematical ability which, with the aid of his social en- 
 vironment, he acquires through the adoption of the developed 
 Arabic number system can hardly be imagined. Certain it 
 is that his forms of thought are now dominated by the 
 social system into which he is born, and this system was 
 in turn borrowed in toto from non-European nations. 
 
 Social world unified through common forms of thought. 
 There is in this acceptance of the social system not only an 
 
230 PSYCHOLOGY 
 
 economy which operates to the advantage of the individual, 
 but there is the additional fact that the individual becomes 
 thereby a part of the social whole in a fashion which is sig- 
 nificant for society as well as for himself. We are bound 
 together as intelligent beings by the common systems of 
 tradition and language to a degree which makes us no longer 
 centers of merely individual adaptation, but rather parts of 
 a general organization which has a certain unity and exer- 
 cises a dominating influence over many individuals. This 
 social unity perpetuates customs and practices so that we 
 have, in addition to the bodily structures which we inherit, 
 a social heredity which guides us in the activities of per- 
 sonal life. Language is the chief medium for this social 
 heredity. 
 
 Changes in words as indications of changes in individual 
 thought and social relations. It is in connection with the 
 development of social institutions that we find the most radical 
 changes in human language. If an individual comes upon a 
 new idea and coins a new word for its expression, the new 
 word gains standing and comes to be a part of the perma- 
 nent language of the community only when others feel the 
 same necessity as the inventor of the word for this new 
 means of expression. When, therefore, we have a long his- 
 tory of variations in any word we may depend upon it that 
 there has been a corresponding series of social as well as 
 of individual experiences related to the word. The detailed 
 history of words is a detailed history of individual mental 
 attitudes toward the world, and at the same time a detailed 
 history of the social relations in which individuals have joined. 
 
 Illustration of change in words. It will not be in place in 
 this connection to enter into any elaborate linguistic studies, 
 but one illustration may be used to indicate something of 
 the character of the psychological and social study which 
 grows out of the history of words. In his '' English Past 
 and Present,'' Trench gives an account of the development 
 
SPEECH AS A FORM OF BEHAVIOR 231 
 
 of the word ''gossip/' This word was originally used at bap- 
 tismal ceremonies and referred to the sponsor who stood for 
 the child in a way analogous to that in which to-day the god- 
 parent stands as sponsor for the child. The first three letters 
 of the word '' gossip " are derived directly from the word 
 ''God," and the second part of the word, namely ''sip," is 
 a modification of the word " sib," which is even now used 
 in Scotland to indicate a relative. When the social institu- 
 tion of baptism was a matter of larger community signifi- 
 cance than it is to-day, the word was needed to express the 
 relationship of the individuals involved in the ceremony ; 
 but being a general form of expression rather than an image 
 of a particular individual, it came easily to refer to other 
 phases of social contact than that which was primarily thought 
 of in connection with the baptismal ceremony itself. The 
 worthy sponsors of the child unquestionably indulged, even 
 in the early days of the ceremony, in certain exchanges of 
 information with regard to other members of the community, 
 and this social function which the individual served was very 
 readily connected with the word coined to refer primarily to 
 the religious function. As the religious ceremony came to be 
 less and less elaborate, and there was a decreasing demand 
 for reference to the religious function, the word gradually 
 drifted over to the second phase of meaning. It is probably 
 true that the aberration of form, which appears in softening 
 the d in'' God" to an s, made this transfer of meaning easier. 
 Indeed, as we have seen at various points in our discussions, 
 words become true symbols only because they are simplified 
 so as to take on easily new types of relation. Thus, the 
 word "gossip" ultimately lost its original meaning and came 
 to signify something which it signified only very vaguely to 
 the minds of those who first used it. Furthermore, it is 
 clear that this transfer of meaning is directly related to the 
 development of the social institution with which the word 
 was connected. The mental attitude of the individual who 
 
232 PSYCHOLOGY 
 
 uses the word to-day and the social character of the insti- 
 tution are both entirely different from the attitude and 
 institution of earlier times. 
 
 Words as instruments of thought beyond immediate ex- 
 perience. Other illustrations of the developments which take 
 place in language can be found in the introduction of new 
 words with new inventions and new discoveries in science. 
 Once the habit of using words is thoroughly established in 
 a community or individual, it furnishes an easy method of 
 marking any experience which it is desired to consider apart 
 from the general setting in which that experience appears. 
 If to-day a civilized individual wishes to think of certain 
 relations such as the physical force of gravity, or the eco- 
 nomic facts of value, and to consider the bearings of the 
 factors which enter into these relations, he will devise some 
 word or phrase by which to mark the relations and hold 
 them clearly before his thought while he considers all of the 
 facts. There comes to be thus a system of experiences which 
 we are justified in describing as constructed in consciousness 
 for the purpose of guiding attention ; these constructs have, 
 as contrasted with ordinary mental images, very little con- 
 tent. Indeed, the reduction of the content of thought to the 
 lowest possible minimum is the tendency of all mental evo- 
 lution. The child has undoubtedly a more concrete imagery 
 than the adult. The adult finds as he learns to use words 
 fluently that the imagery which at fi.rst was necessary to ex- 
 plain them falls away. The result is that great ranges of 
 thought can be much condensed ; as, for example, when all 
 the cases of falling bodies are thought of at once under the 
 single term '' gravity.'' In the discussion of habits it was 
 shown that as experience becomes more completely organ- 
 ized into habits, the memory content and even the sensory 
 contents receive less attention. An organized attitude is sub- 
 stituted for a complex of content factors. In somewhat 
 analogous manner, words may be regarded as rneans of 
 
SPEECH AS A FORM OF BEHAVIOR 233 
 
 epitomizing consciousness, while they permit the highest 
 type of ideational elaboration of experience. The widest 
 variety of content factors may be related to words ; that is, 
 the use of a word is often cultivated under the guiding in- 
 fluences of concrete content, as when the child builds up 
 the idea of animal through direct perceptual contact with 
 dogs and horses. After a time the concrete memory images 
 attached to the word fade out and leave the word as a 
 substitute, as a minimum content to which (as when the 
 man condenses his whole attitude towards all kinds of ani- 
 mals into a single compact experience) an elaborately organ- 
 ized meaning may attach. 
 
 Images and verbal ideas. When, therefore, we ask what 
 it is that a person thinks of in his use of a word, we shall 
 certainly go astray if we attempt to answer that the word 
 calls up all of the concrete experiences with which it has 
 been connected and with which it may be connected. For 
 example, let the reader ask himself what presents itself in 
 consciousness when he sees the word '' animal." It would 
 be still better if, instead of choosing some word thrown into 
 the text as an isolated illustration, we should ask the reader 
 to give an account of the mental experiences through which 
 he passed when he observed one of the words that came 
 in the course of the general discussion. For example, what 
 was called up a moment ago when the eye passed the very 
 definite word ''text" ? The answer to these questions with 
 regard to the content of consciousness at the moment of 
 recognition of words will certainly not be that the mind is 
 filled with trains of concrete images. 
 
 Mental attitudes as characteristic phases of verbal ideas. 
 The consciousness of a word has sometimes been described 
 as a feeling or an attitude, and such a description as this 
 unquestionably comes nearer to the truth than does the 
 explanation of meaning through images, which has some- 
 times appeared in psychological discussions of this matter. 
 
234 PSYCHOLOGY 
 
 A general term such as '* animal" or ''text" turns the 
 thought of the reader in one direction or the other without 
 filling the mind with definite contents. The content of experi- 
 ence arises rather from the total phrase or sentence ; the 
 single word indicates only the direction in which this content 
 is to be sought, or in which it is to be applied in some future 
 stage of mental activity. For example, if I say that all ani- 
 mals are subject to man's dominion, there is much more of 
 attitude in the whole experience than there is content. We 
 look down upon the animals ; we feel their inferiority ; we 
 recognize ourselves as above them. The attitude of mind 
 experienced is the all-important fact. There is an experi- 
 ence of personal elation, which may perhaps be worked out 
 into imagery, if one contemplates it long enough. Thus, 
 one may turn the thought into images by thinking of him- 
 self for the moment as the representative man looking down 
 upon the animals gathered as he saw them in childhood in 
 some picture of Adam naming the animals. But all this 
 concreteness in one's description of the animals and of him- 
 self is recognized as too picturesque to be true to ordinary 
 experience. We can stop and fill out the attitude with ap- 
 propriate imagery if we like, but we do not ordinarily do 
 so. The truer statement is that the idea comes as a single 
 simple attitude and prepares one to go on from a position 
 of superiority to some appropriate sequent relation. The 
 value of the words lies in the fact that they carry experi- 
 ence forward, furnishing only so much content as is neces- 
 sary to support thought without overloading experience with 
 all the detail. 
 
 Other illustrations of thought relations. Again, take 
 another illustration which shows that there may be nicety of 
 shading in our thought relations without much content. If 
 v/e use such a word as '' savage," we are likely to take an 
 attitude of superiority somewhat analogous to that taken 
 toward the animals, but flavored more than the former idea 
 
SPEECH AS A FORM OF BEHAVIOR 235 
 
 with a concession of equality. If we speak of higher beings, 
 such as angels, we assume an entirely different attitude, 
 without necessarily giving ourselves the trouble to fill in 
 any definite content. Indeed, the content of any thought 
 referring to the higher beings is recognized everywhere as 
 more or less of a makeshift, in that we fill in the unknown 
 with such images as we can borrow from ordinary life, the 
 images being symbols, not true representations. 
 
 Concrete words. All this has been expressed by certain 
 psychologists in the statement that general ideas are in es- 
 sence nothing but dispositions toward activity. Here we have 
 a formula which is very closely related to the formula which 
 we derived in our discussion of the development of percepts. 
 There are, undoubtedly, direct motor habits and consequent 
 attitudes in connection with many concrete words. It is, on 
 the other hand, probably not true that the bodily attitude as- 
 sumed when we think of the word ''animal" is anything like 
 a complete bodily attitude such as would be assumed in the 
 presence of animals in concrete experience. The mental 
 attitude aroused by the word probably has as its direct physi- 
 ological parallel a bodily movement which is a much-reduced 
 resultant of earlier direct attitudes. It is in its present form 
 merely a faint reverberation, significant not for direct adap- 
 tation but merely as a step in the development of a general 
 and perhaps very remote form of activity. The present atti- 
 tude is one of those indirect forms of human adjustment 
 which render the experience of man freer and more idea- 
 tional than the experience of the animals. The bodily move- 
 ment in such cases is symbolical and transient, assumed 
 merely for the sake of carrying the individual forward into 
 a more complete state which lies beyond. 
 
 Examples of words arousing tendencies toward action. The 
 matter may be made clear by considering what happens when 
 by means of words one is told that he is to go first to the 
 right until he reaches a certain place, and is then to turn 
 
236 PSYCHOLOGY 
 
 toward the left and go straight ahead. There are clearly cer- 
 tain tendencies toward direct bodily movements aroused by 
 the words '' right " and '' left " and '' straight ahead." These 
 tendencies toward movement, it is true, are not significant as 
 present adaptations to the environment ; they are significant 
 merely because they give the thinking individual a certain 
 tendency, which may, indeed, work itself out later in a much 
 more fully developed and concrete form, but is at present a 
 kind of suppressed, incipient form of action. If one has 
 thought out a series of movements toward the right and left, 
 he will have developed within himself a form of behavior 
 which, on the presentation of the appropriate stimulation in 
 the form of the signpost or building at which he is to turn, 
 will serve as a sufficient preliminary organization to arouse a 
 significant anc| concrete form of behavior. The preliminary 
 thought attitude and faint bodily expression serve, therefore, 
 in a tentative way to aid subsequent direct adaptations. 
 
 Abstract words. If, now, we choose as our illustration 
 not words of direction but abstract phrases, such as the 
 phrases by which men are exhorted to patriotism, obviously 
 the emotional stirring which one feels as the result of these 
 exhortations is by no means adequate to explain the true sig- 
 nificance of the word ''patriotism." A man cannot become 
 truly patriotic by going through the inner stirrings which this 
 word arouses. Indeed, in not a few cases vague emotional 
 responses check rather than promote the development of true 
 interpretations because the vague response satisfies the need 
 of the mind for experience but gives no complete or adequate 
 content. The trouble with the emotional response lies not 
 in the fact that it is emotional but in the impossibility of its 
 expressing fully the whole significance which the word must 
 carry. Such an abstract term as that under discussion can be 
 made potent for direct bodily organization only when it is 
 supplied through proper settings with some definite and final 
 purpose of an active kind. To be truly patriotic one must be 
 
SPEECH AS A FORM OF BEHAVIOR 237 
 
 aroused to some definite form of public service. The final 
 purpose will then be like the concrete words '' left " and 
 '' right." The abstract word taken alone is the expression of 
 a relation. If it is treated as a final factor of experience, it 
 will dissipate itself in vague emotional reactions. 
 
 To take still another illustration : If in the course of a 
 scientific discussion one is told that a certain problem needs 
 very much to be investigated, the word '' problem " will arouse 
 within the individual some kind of a responsive attitude which 
 can be described in a general way as an attitude of hesitation, 
 of turning hither and thither in the search for a solution. But 
 the conscious process will be more than the attitude of hesi- 
 tation and turning, for it will have a form and significance 
 determined by the whole train of ideas into the midst of which 
 this attitude of hesitation and turning is injected. Thus, if 
 the problem is in geology, the attitude of inquiry will be very 
 different from that which would be assumed if the train of 
 thought related to astronomy. We may therefore speak of 
 the attitude aroused by the word ''problem" as wholly rela- 
 tional in its character. Another way of expressing the matter 
 is to say that the attitude is in the world of ideas for the time 
 being rather than in the world of practical adjustments. We 
 mean by such statements as these that the attitude is merely 
 a temporary step in the process of ideational organization ; it 
 is not an immediate reaction on any object. It is an indirect 
 and elaborate phase of adaptation ; it has value and signifi- 
 cance because of the turn which it gives to the ideational 
 process rather than because of the concrete imagery or 
 reaction to the world of things. 
 
 Contrast between concrete images and abstract ideas. The 
 indirectness of verbal forms of consciousness and of the re- 
 lated nervous processes involves, as has often been noted in 
 discussions of language, certain dangers of possible malad- 
 justment. Concrete images and direct forms of experience 
 cannot, because of their limited nature, be turned in very 
 
238 PSYCHOLOGY 
 
 many directions. Verbal ideas, on the other hand, espe- 
 cially if they are abstract, are capable of a great variety of 
 connections because they are so meager and schematic in 
 individual content. 
 
 Besides this, there is a disadvantage in the use of ab- 
 stract terms in that two individuals, while they may start 
 with the same general tendency of attention, may, in the 
 course of the use of the words, drift apart, without being as 
 clearly conscious of their divergence from each other as they 
 would be if they dealt constantly with concrete percepts. It 
 is a much more definite method of interchanging ideas to 
 demonstrate the objects themselves, or to demonstrate some 
 concrete representations of the objects, such as pictures or 
 models. If one does not have pictures or models, he natu- 
 rally tries to correct the errors which are likely to creep in 
 when he is using words, by calling up from time to time as 
 concrete an image in the mind of his listener as it is possi- 
 ble to evoke by the use of words. We all of us feel the relief 
 in any continued discourse when a figure of speech, or an 
 illustration, is used. The figure of speech gives us a fairly 
 concrete image with which to deal. The image in this case 
 may be remote from the immediate subject of thought, it may 
 be related to the present discussion only as a kind of rough 
 analogy, but the presence of some characteristic which illus- 
 trates and renders concrete the abstract discussion is a relief 
 in the midst of abstract relational terms and furnishes the 
 means of correcting possible tendencies toward divergence 
 of thought between the speaker and the listener. An illus- 
 tration is even more definite in its character, and so long as 
 it calls up in the minds of the speaker and listener the same 
 kind of concrete images, it is a direct corrective of the possible 
 looseness of verbal thought and verbal communication. 
 
 Particular images as obstructions to thought. How far 
 one should be picturesque in his language, and how far one 
 should, on the other hand, use terms which are not related 
 
SPEECH AS A FORM OF BEHAVIOR 239 
 
 to definite mental pictures, is a matter which must be deter- 
 mined by the demands of the particular situation at hand. It 
 would be quite impossible in any generalized science like 
 physics continually to deal with concrete illustrations. If the 
 scientist speaks, for example, of the general law of gravity, 
 he cannot be dealing with all of the specific cases of gravity 
 known to his, experience, nor can he feel himself bound to a 
 single illustration. He may come back to the single illustra- 
 tion in order to hold his verbal idea true to the concrete facts, 
 but he should cultivate the ability to get away from the con- 
 crete cases into the wider sweep of thought which is covered 
 by the general word. 
 
 Ideas or indirect forms of experience characteristic of man. 
 In concluding this discussion of language it will be well to 
 reiterate that human life has taken on, through the develop- 
 ment of indirect modes of consciousness and behavior, an 
 aspect which differentiates it altogether from the life of ani- 
 mals. The consequences for human nature of the evolution 
 of a mode of reaction such as speech is, are unlimited in im- 
 portance. The full significance of this unique mode of be- 
 havior will become increasingly apparent as we canvass in 
 detail the problems of ideation and abstraction. 
 
CHAPTER XI 
 
 MEMORY AND IDEAS 
 
 The problem of describing ideas. Throughout the last chap- 
 ter reference was made to ideas without any effort to describe 
 in full these important phases of experience. It now becomes 
 necessary for us to take up the treatment of ideas and of the 
 complex processes of thought which are made up of ideas. 
 
 The way has been prepared for this discussion by the con- 
 clusions reached in all earlier chapters. Let us review briefly 
 the essentials of our earlier studies. First, animals develop 
 inner states in their efforts to respond to sensory stimuli. 
 Second, the higher animals become increasingly able to carry 
 on elaborate internal readjustments. Corresponding to these 
 elaborate readjustments are certain complexes of sensations 
 and certain attitudes which gradually grow more and more 
 highly differentiated. Third, the inner organization of man 
 and his closest relatives in the animal world is such that ex- 
 perience is progressively recorded in the form of habits of 
 reaction and corresponding mental states. 
 
 We are now ready to ask what is the form of this inner 
 enriched mental life which man develops in the course of 
 experience. Our popular language is well supplied with w^ords 
 referring to these products of experience. We say that man 
 stores up in memory ideas and thoughts. We speak of re- 
 calling the past, of images in the mind, of an inner world 
 of thoughts and thought relations. 
 
 Ideas not derived from present impressions. In all such 
 phrases as the above there is a sharp contrast between 
 present sensory impressions and the experiences which are 
 
 240 
 
MEMORY AND IDEAS 241 
 
 brought over from the past. There is also a recognition of 
 the overwhelming volume of past experiences. The indi- 
 vidual faces the world of the present moment with a mind 
 set and prepared through long training. What we call 
 intelligence is not the impression of the moment but a 
 body of experiences drawn out of the past. 
 
 Ideas as revivals. Let us consider some of the simplest 
 types of ideas. If one closes his eyes and thinks of the 
 scene which a moment before impressed itself upon his 
 vision, he will recognize that his consciousness is filled with 
 a substitute for direct visual sensations and percepts ; this 
 substitute is called a memory image. When one thinks of 
 an absent acquaintance, the memory image may contain 
 factors which are substitutes for direct auditory impressions 
 of the voice. When one thinks of a rough surface without 
 touching it, the image contains substitutes for tactual factors 
 and their perceptual organization. These illustrations serve 
 to emphasize the scope of the word ''image," which it will 
 be seen is used not merely for vision but also for all spheres 
 of experience. 
 
 Advantages of relative independence of sensory impres- 
 sions. Before taking up any of the details regarding the 
 character and laws of memory images, it will be well to 
 dwell briefly upon the great advantage to the individual of 
 possessing these substitutes for direct impressions. The 
 mind supplied with memory images is relatively independent 
 of contact with objects ; the images may serve as the basis 
 for attitudes and for reconstructive organizations which may 
 be of the highest significance in individual life. A common- 
 place illustration of this advantage is seen whenever one 
 runs over in his mind the various places in which he has 
 been and where he might have left a lost object. More 
 complex illustrations may be drawn from the mental activi- 
 ties of an inventor who thinks out many combinations, thus 
 using the . irnages in consciousness as substitutes for real 
 
242 PSYCHOLOGY 
 
 objects. To be sure, there are certain disadvantages which 
 connect themselves with these advantages. The inventor can 
 make more mistakes in this imagery than he could if he 
 tried to fit together real things, and one's false memory of 
 where he left his property may lead him far astray. But 
 taken in the large, the freedom from the necessity of always 
 waiting for direct impressions is one of the great superiorities 
 of the higher forms of mental life. 
 
 Individual variations in imagery. One of the most im- 
 portant statements to be made in the description of memory 
 images is that different individuals show great differences in 
 the character and vividness of their memory images. Some 
 years ago Galton asked a number of individuals to test their 
 mental imagery by calling up as definitely and fully as possi- 
 ble the familiar objects of the breakfast table. After the 
 memory image had been called up, the observer was requested 
 to state how clear the mental image was in color and form 
 and other characteristics. Some of the observers said that 
 they recalled objects with a vividness and detail altogether 
 comparable to their perceptual experience. These Galton 
 called good visualizers. Others described their memory 
 images as extremely vague and hazy. Still others, who were 
 between the extreme classes, stated that their mental images 
 were restricted in extent and were relatively fainter than the 
 percepts themselves but, nevertheless, fairly comparable in 
 general character to direct sensory experiences. Galton's 
 tests have frequently been repeated, and his results have 
 been fully corroborated. Furthermore, it has been found 
 that persons who have faint visual images have, in some 
 cases, vivid auditory images. Some persons have vivid tac- 
 tual imagery or vivid memory of movements. The blind, 
 for example, can have no visual memories ; their memory 
 consciousness must therefore be filled by a totally different 
 type of content from that which exists in the mind of the 
 normal individual. 
 
MEMORY AND IDEAS 243 
 
 The accidents of individual experience and mental imagery. 
 
 Not only is the type of memory very different in different 
 individuals, but the special contents differ according to the 
 accidents of individual experience. Thus, if two persons 
 have looked at the same scene from two different points of 
 view, their imagery will be different ; certain near and vivid 
 factors for one person will be vague and remote for the 
 other. Then, too, individual attitudes react upon the con- 
 tents of experience to determine the character of imagery. 
 If an especially pleasing or disagreeable color has been pre- 
 sented to a given individual, it may continue in his memory 
 for a long time, while a second individual looking at the 
 same color, but not greatly pleased or displeased by it, may 
 very soon forget it altogether. 
 
 Dependence on vividness and recency. In spite of indi- 
 vidual differences in mental imagery, there are certain gen- 
 eral statements which apply to all persons and all types of 
 memory. All other conditions being equal, memory de- 
 pends upon the vividness and recency of the sensory im- 
 pression. It should be noticed that memory does not depend 
 on intensity but on vividness. If intensity results in the con- 
 centration of attention upon the impression, then intensity 
 may indirectly help to fix the impression ; but a faint 
 impression upon which attention has been centered will 
 continue in memory long after the disappearance of an imi- 
 pression which passes without attention. The recency of an 
 impression is also a matter of importance. Careful quanti- 
 tative tests show that impressions fade with relative rapidity 
 at first and at a very gradual rate later. We forget many 
 impressions entirely in the first few moments after they are 
 received. What we retain beyond the first brief period is 
 more likely to continue as a relatively permanent addition 
 to the content of consciousness. 
 
 The training of memory. Much may be said with regard 
 to the scope of memory and with regard to the possibility 
 
244 PSYCHOLOGY 
 
 of increasing the scope of memory by training. It is doubt- 
 less true that the abihty to retain impressions differs greatly 
 with different individuals ; some retaining many impressions 
 and carrying them forward through long periods, others 
 having little or no ability to retain. So clearly marked are 
 these natural characteristics of different individuals that the 
 changes produced through practice are relatively small. In- 
 deed, Professor James asserts that there is no possibility of 
 changing the degree of natural retentiveness through train- 
 ing. This statement has been shown to be out of harmony 
 with the facts, for there are evidences of increase in the 
 scope of memory through training. Nevertheless, Pro- 
 fessor James's statement is probably much nearer the truth 
 than the popular assumption that memory can be radically 
 changed through practice. 
 
 Retention as distinguished from recall. Another general 
 fact regarding memory is that experiences are not actively 
 recalled without some present impression or related memory 
 which serves as the m.otive or occasion for the exercise of 
 memory. The mere retention of an impression is not the 
 whole of memory. For example, at this moment there must 
 be retained by every reader of these words hundreds of 
 proper names. There is no motive for the recall of most 
 of them. If one should find in the text, however, such a 
 phrase as ''author of the Iliad," one of the proper names 
 would be recalled and memory would become active for that 
 one name. This name might in turn suggest other memories. 
 The fact that memories are thus linked together and that 
 active recall is always a matter of a train or sequence of 
 processes was noticed long ago by Aristotle. He described 
 the principles of memory, or, as they were later designated, 
 the laws of association. There are two general principles 
 of association which we may note : first, the principle of 
 association by contiguity ; and, second, the principle of 
 association by similarity or contrast. 
 
MEMORY AND IDEAS 
 
 245 
 
 Association by contiguity. When one thinks of the letter 
 A he is very hkely to recall also the letter B^ because the 
 two have so often followed each other in experience. The 
 first line of a poem suggests the second ; the sight of one 
 of two intimate friends suggests the other. In general, 
 when two experiences have been intimately related in earlier 
 experience, the appearance of one is likely to serve as a 
 sufficient motive for the recall of the 
 second. 
 
 Association by similarity. When 
 one sees a face which has eyes, or 
 nose, or mouth like those of another 
 person, the like feature is in many 
 cases enough to recall the absent 
 person. In such a case as this the 
 two faces now associated need never 
 have appeared together in the past ; 
 it is enough that they contain the 
 same feature. This relation between 
 two experiences having a common 
 factor is evidently a more complex 
 fact than association by contiguity, 
 for it involves a sufficient analysis 
 or concentration of attention upon a 
 single feature to separate it from its 
 present surroundings and make it the link of connection with 
 a group of experiences not now present. The diagram in 
 Fig. 57 represents the situation. The circle A represents a 
 single feature of the face now seen \ b, b, b are the other 
 features. In a past experience, A has been part of a system 
 of features of which c, <:, c, were the others. If A becomes 
 the subject of special attention, it can revive the elements 
 c, c, c^ and thus detach itself from b, b, b the features of 
 the present complex in which it stands. In general, then, 
 whenever a factor of experience now present has appeared 
 
 ^^^ 
 
 Fig. 57. Association by 
 similarity 
 
 The full-drawn circles repre- 
 sent the elements of the pres- 
 ent experience. Of these ele- 
 ments A attaches itself also 
 to the system of elements rep- 
 resented by the dotted line 
 circles. A, when taken with 
 the circles 3, b, b, constitutes 
 the present experience ; A, 
 when taken with the circles 
 c^ c, c, constitutes the recalled 
 experience. A is obviously 
 the center of relations be- 
 tween the two systems 
 
246 PSYCHOLOGY ■ 
 
 in earlier experiences in a different combination, the earlier 
 combination may be recalled through association by similarity. 
 
 Association by contrast. Association by contrast will be 
 clear after the foregoing discussion of association by simi- 
 larity, for no contrast can exist without like elements. One 
 may contrast a candle and the sun because they both give 
 light, or the moon and a coin because they are both round, 
 but in each of these cases the basis of the contrast is a 
 common factor. 
 
 New products evolved in ideation. Thus it is seen that 
 memory images do not represent merely the traces of earlier 
 experiences, but by continual association and readjustments 
 memory images change their character and in the later 
 stages show quite as much the effects of readjustments in 
 mental life as the results of initial impression. When two 
 ideas have been associated by contrast, there is an analysis 
 which tends to break up the original memory images and 
 bring to clear consciousness one element of the associated 
 ideas together with what we may properly call the new idea 
 of contrast. When the idea of contrast arises, the descrip- 
 tive term '' image " becomes less appropriate than it was 
 for the simple ideas with which the discussion began. 
 
 Ideas not all images. The idea of contrast is an idea of 
 a higher type. It is very difficult to state what is the con- 
 tent of such an idea. It is a kind of shock of difference, 
 a feeling of intellectual opposition. Indeed, there are many 
 psychologists who insist on the use of the term ''imageless 
 thought " in describing such an idea. They mean by this 
 term to draw attention to the fact that the mind deals at 
 these higher levels not with definite revivals of sensory con- 
 tent but with certain tendencies of consciousness which are 
 to be sharply distinguished from memory images. Perhaps 
 the best description which can be given will be by the use 
 of an analogy. The mind is calling up a series of images 
 when suddenly it turns in a new direction. The abrupt 
 
MEMORY AND IDEAS 247 
 
 turning is a real experience, often very vivid and important 
 for all later thinking. Just at the moment of turning there 
 must have been an experience. What was the experience 
 of turning ? It was an experience which linked together 
 two images, but it was not in itself an image. 
 
 Tendency to revert to imagery type. The more complex 
 ideational experience becomes, the more elements there are 
 which must thus be described as imageless. On the other 
 hand, it is to be noted that there is a tendency to develop 
 devices by which the mind can mark and hold steadily 
 before it these imageless ideas. When one has had the 
 experience of contrast, one tends to mark the experience 
 by a word which will give it enough content to make it 
 a stable unit in thought. 
 
 Advantages of indirect forms of experience. All these 
 statements draw attention to the fact that ideas are, more 
 than any other phase of experience, flexible and subject to 
 inner readjustment. Thus, even when dealing with revivals 
 of perceptual experiences every person has his own peculiar 
 image depending on his point of observation and his per- 
 sonal powers of retention. Courts of law are familiar with 
 this fact and attempt to eliminate by comparison of much 
 testimony the purely personal elements which always attach 
 to a memory image. 
 
 The flexibility of ideas, as has already been pointed out, 
 may be of great advantage because it puts the individual in 
 possession of a device for thinking out changes in the per- 
 ceptual world. When men put together ideas, they do so 
 because ideas are flexible. If they get them put together 
 in a productive way, they often make up a model to which 
 later the hard material world may be made to conform. 
 
 We are brought by this statement, as we have been sev- 
 eral times before, to a recognition of the distinction between 
 direct and indirect modes of adjustment to the world. The 
 physiological conditions necessary to the formation of ideas 
 
248 PSYCHOLOGY 
 
 are undoubtedly provided for in the nervous processes which 
 go on in the association areas of the cerebrum. In the 
 lower animals, where the association areas are small or 
 lacking, there is little evidence of ideas. In these animals 
 sensory processes pass to motor discharge with greater 
 directness than in man. In like manner the infant seems 
 to be wholly absorbed in percepts. This is related to the 
 fact that the tracts in the association areas are the latest to 
 develop, the process of development being, as noted in an 
 earlier chapter, distinctly traceable for a period after birth. 
 Animal behavior direct and perceptual, human behavior 
 indirect and ideational. The significance of the evolution 
 of the association areas can be seen by contrasting the 
 modes of human behavior with the modes of behavior ex- 
 hibited lower in the scale of life. If an animal is aroused 
 to anger by some stimulation, it responds by directly attack- 
 ing the source of the stimulation. If an animal is pleased 
 by some form of agreeable excitation, it makes clear its 
 pleasure in an immediate reaction. There is in animal life 
 very little delay or indirection in response. When we con- 
 trast all this with human life, we are impressed by the fact 
 that man's activities -are most of them indirect. They re- 
 quire more time to mature. Thus, if a man sees an object 
 passing before him, he may be thrown into a long train of 
 thought rather than into a direct series of activities. The 
 long train of thought is possible because man has a com- 
 plex central nervous system through which the impression 
 may circulate before it passes out as a motor impulse. Or 
 man's action may be indirect in another sense, as was shown 
 in the chapter on speech. Instead of attacking the object 
 directly, he may call his neighbor and talk the matter over 
 with him, ultimately arriving at a mode of action only after 
 a long series of verbal preparations and plans which are 
 indirect and related onlv in the most remote fashion to the 
 object which yielded the original impression. 
 
MEMORY AND IDEAS 249 
 
 The world of ideas comes ultimately to be a world of 
 superior importance. Its laws of association are free and 
 independent of the world of things. One can think of the 
 cities of the country as belonging together because in the 
 mind cities are associated, while in reality they are held 
 apart by great stretches of territory. 
 
 Influence of ideas on things. The result of the evolution 
 of this inner world of ideas is that man ultimately puts 
 together not only in his mind but in his actual conduct 
 elements of the world which would never have been put 
 together except for the laws of mental association. The 
 laws of association are thus made to dominate the world 
 of things. 
 
 Tool-consciousness, Take, for example, the invention of 
 tools. Primitive man was cut by a stone or torn by a 
 thorn. Did he merely cry out with pain as an unintelli- 
 gent animal might ? Not at all. He saw that the sharp 
 edge which had injured him might be of great use to him 
 if it could be brought into new relations. So he picked 
 up the stone and plucked the thorn and put them to the 
 uses which he saw first in his own mind and afterward 
 realized in material readjustments. 
 
 Knowledge of nervous process limited. It must be 
 frankly admitted that this discussion has carried us beyond 
 our knowledge of the conditions in the nervous system. 
 We know in a general way what association areas are, 
 but we do not know the details of their organization. We 
 know ideas introspectively more intimately than we know 
 their objective conditions. 
 
 Traditionally, psychology has begun with ideas and given 
 less attention to those lower and simpler forms of experi- 
 ence with which we dealt in earlier chapters. For this 
 reason the science of psychology has suffered in its rela- 
 tions to the biological sciences. Either ideas have been 
 thought of as facts wholly apart from bodily life or they 
 
250 PSYCHOLOGY 
 
 have been declared in a vague way to be dependent on 
 laws of physical being. Psychology has oscillated between 
 a purely theoretical spiritualism and a crass materialism. 
 The mind has been regarded either as wholly distinct or 
 as part of the bodily phenomena. 
 
 Consciousness as product of evolution. The view to which 
 our study has led us can be expressed in evolutionary terms. 
 Gradually the animal world, in working out its reactions to 
 the environment, has evolved an inner world conditioned 
 by indirect and tentative reactions. This inner world is 
 social in many of its characteristics ; that is, it is a world 
 through which individuals of the same type are drawn into 
 sympathetic communication. The inner world is one in 
 which ideas as substitutes for things are rearranged. The 
 inner world is thus distinct from the lower levels of bodily 
 adjustment, but is at the same time a part of the economy 
 of individual relation to the world and is directly evolved 
 out of. the efforts at direct adjustment. 
 
 Such an explanation of the place of consciousness in 
 evolution gives us the fullest justification for our emphasis 
 on those aspects of ideas which are not copies or reproduc- 
 tions of sensory impressions but new modes of rearranging 
 experiences. 
 
 We shall continue our discussion, accordingly, with a 
 treatment of the changes produced in experience through 
 the most elaborate rearrangements in ideas. *" . 
 
CHAPTER XII 
 
 IMAGINATION AND THE FORMATION OF 
 
 CONCEPTS 
 
 Adaptation through ideas. The animal adapts itself to 
 its environment by cultivating better modes of direct reac- 
 tion, such as greater speed of running or greater skill in 
 the use of its teeth or claws. Gradually there appears 
 in the highest animals a new mode of adjustment in the 
 tendency to organize into social groups. The social group 
 is a protective device which gives the individual greater 
 strength than he can cultivate in his own individual organ- 
 ism. As soon as the social group evolves there must grow 
 up, and there do grow up, types of activity designed to 
 hold the group together. In man this latter phase of evo- 
 lution culminates, and social cooperation becomes one of the 
 dominant facts in life. No longer does man compete with 
 his enemies by cultivating greater and stronger muscles ; 
 he meets the struggle for existence by social cooperation. 
 His reactions on the world are in large measure indirect. 
 He invehts a world of social forms which can be described 
 only by saying that it is an artificial environment of human 
 making. 
 
 In a very real sense this means the evolution of a new 
 type of adaptation. The competitions of human life are at 
 a new level, whollv different from those of animal life. 
 The character of this new type of adaptation can be studied 
 through an analysis of one system of human behavior such 
 as commerce, which has no parallel whatsoever in the 
 animal world. 
 
 251 
 
252 PSYCHOLOGY 
 
 Early stages of barter. In the earliest stages of exchange 
 the parties to the transaction demanded direct contact with 
 the objects bartered. Even at this primitive stage much 
 self-control and much regard for social relations are ex- 
 hibited. The fact that men will barter at all proves that 
 they have cultivated ideas to the extent of refraining from 
 mere brutal seizure of that which they desire and to the 
 extent of realizing the possibility of giving up one thing 
 for another. Barter involves in its crudest form some 
 powers of thought and some attention to social relations. 
 But barter is always perceptual in its demand that the 
 commodities to be exchanged be directly accessible in 
 tangible and visible form. 
 
 Barter perceptual. The stories of primitive barter which 
 show the savage duped by the gaudy color of cheap wares 
 bear eloquent testimony to the fact that perception is at 
 this early stage not yet replaced by ideas. 
 
 Standard values. After barter began to be understood 
 and widely practiced, there was cultivated a desire for uni- 
 formity ; that is, for standard methods of exchange. Some 
 commodity more durable in its qualities than the rest began 
 to serve as a common standard to which all transactions 
 were referred. Among hunting tribes all barter is standard- 
 ized in terms of furs. In grazing communities sheep and 
 cattle become the standards. Through the use of such 
 standards, ideas of uniform value were developed, and the 
 mere showy perceptual characteristics of objects receded 
 into the background. 
 
 Symbolic values. The next step in exchange comes 
 when some very permanent commodity takes on symbolic 
 value. Wampum is prized not alone because it is a beau- 
 tiful string of shells but because it serves as a counter and 
 may be passed around as a promissory note for future 
 delivery of a stipulated number of pelts or tents or arrows. 
 By the time this stage is reached we must assume high 
 
IMAGINATION AND CONCEPTS 253 
 
 powers of association. Wampum has value now because 
 it calls up ideas and because the social group in increasing 
 measure guarantees the ideas connected with the symbol. 
 
 As with wampum, so with the metals. The ideational 
 values are finally marked on the metal. Then comes the 
 paper substitute for the metal and finally the various forms 
 of commercial credit of modern commerce. One has only 
 to represent to himself the scene which would follow if a 
 bank note were offered to a savage hunter in exchange for 
 game to realize how far from direct perceptual experience 
 modern commerce has gone. 
 
 Evolution from perception to ideas. This sketch of the 
 evolution of barter into commercial exchange could be par- 
 alleled in every field of human action. Manufacturing with 
 machinery has replaced the simpler direct contacts of primi- 
 tive life. Travel by borrowed power of animals and finally 
 by mechanical forces has largely replaced migration of the 
 savage type. Sanitary regulations and settled modes of urban 
 life have replaced the life of the forest and the wilderness. 
 
 How has all this evolution come about ? There is one and 
 only one answer. Man has learned to combine and recom- 
 bine ideas, to call on his neighbor for cooperation and for 
 the further comparison of ideas, and to meet the needs of 
 life indirectly rather than by direct perceptual responses. 
 
 Higher controls of conduct. The transformation of life 
 thus outlined has not gone on without bringing about the 
 most radical internal changes in the mind of man. To 
 the direct and vivid emotions which accompany instinctive 
 reaction have been added trains of ideas which lead to 
 deliberate forms of behavior. Human nature has become 
 complex. There is an element of animal life and of primi- 
 tive devotion to perceptions in every man. We shall never 
 outgrow instincts or our native impulses to seize the things 
 about *us. But above and beyond these direct modes of 
 adaptation there is the higher world of ideas. In dealing 
 
254 PSYCHOLOGY 
 
 with this higher world a new type of experience has been 
 evolved. There are new pleasures which come from the fit- 
 ting together of ideas. There are new forms of displeasure 
 which come from the clash of ideas. 
 
 Ideational attitudes. For example, there is a shock when 
 one hears a profane word which is little less than the shock 
 from a physical blow. The name of the Deity has associated 
 itself in all experience with the attitude of reverence, and 
 when this name is taken out of its proper associations and 
 used in a reckless fashion, the emotional recoil is violent. 
 
 Other examples can be drawn from the cultivated demands 
 for the use of proper grammatical forms. The child gradu- 
 ally learns that a plural noun demands a plural verb. The 
 shock which comes from hearing a violation of this rule is 
 quite as unpleasant as the shock from a sharp, cold breeze 
 striking the skin. Furthermore, the inner muscular recoils 
 in the two cases are not unlike. Both involve, among other 
 factors, an interruption of respiration and a change in the 
 rate of the heartbeat. 
 
 Ideas as substitutes for impressions. When we speak of 
 the world of ideas as a real world, all the foregoing con- 
 siderations must be kept in mind. Ideas are real in prompting 
 behavior and in giving directions to our acts. Ideas may 
 be followed by habitual reactions until they come to demand 
 these reactions quite as much as do things seen through 
 the eye or heard through the ear. Ideas may influence the 
 train of attention quite as much as percepts. For example, 
 the man who is lost in thought does not attend to the ob- 
 ject coming toward his eyes. In short, ideas have values 
 comparable in all respects to percepts and in some respects 
 quite superior. 
 
 Imagination as reorganization of ideas. In this chapter 
 we shall discuss some of the changes which take place in 
 this world of ideas, for it is important if we are to under- 
 stand the world in which man lives that we shall know the 
 
IMAGINATION AND CONCEPTS 255 
 
 laws of change in his world of ideas. In an earlier connec- 
 tion the laws of memory were discussed. It was there 
 shown that in som.e measure the mind holds its ideas fixed 
 and brings them back under proper conditions so that past 
 experiences may operate in present surroundings. When 
 ideas are thus carried forward, they are called memories in 
 the strict sense, or sometimes they are called images. It 
 was pointed out in that earlier treatment of the matter that 
 memories undergo a change in experience. We now turn 
 to the more elaborate types of such change. For these 
 types of change there are a number of names. Sometimes 
 ideas are described as imaginations. This term is used to 
 indicate that a mere rearrangement of elements of memories 
 has been made. One imagines a horse with wings. The 
 source of the idea ''horse" is memory, likewise of the idea 
 ''wings," but the union of these two sets of ideas is an act 
 of the imagination. When the combinations which go on 
 in consciousness are purely capricious, we speak of fanciful 
 imaginations. When, on the other hand, recombinations of 
 mental processes are worked out systematically and coher- 
 ently, we speak of scientific imagination. Thus a dragon is a 
 fancy ; the imagination of a Columbus or a Watt is scientific 
 and constructive. 
 
 Personifying imagination. One of the most primitive 
 forms of imagination is that exhibited by savages when 
 they attribute to inanimate objects the personal character- 
 istics which they find in themselves. The savage never 
 thinks of thunder or of the wind without putting back of it 
 in his imagination some personal agency. This form of con- 
 structive thought is the simplest which could originate in 
 a personal consciousness. An emotion of anger is a more 
 direct explanation for a natural catastrophe than is some 
 abstract statement referring to physical force. To modern 
 thought the myths of early peoples seem like the play of 
 the most capricious imagination ; to the mind untrained in 
 
?:«"*«, 
 
 2S6 PSYCHOLOGY 
 
 the forms of critical scientific imagination nothing could 
 be more natural than a myth. Even the trained mind 
 derives pleasure from the personification of objects, because 
 it is easy to use the factors from personal experience in all 
 manner of combinations. 
 
 Imaginations occasions of useless activities. Early man 
 was led by his imaginations to undertake many useless 
 forms of activity. Thus, he attempted to propitiate the 
 personalities which his own mind had put into streams and 
 mountains and trees. There was no direct evidence that 
 his imaginations were not in conformity with the facts, and 
 hence the imaginations went on increasing in complexity 
 until they broke down by their own incoherency. 
 
 Critical tests of imaginations. This reference to the fanci- 
 ful imaginations of primitive man introduces us to the 
 discussion of the more productive forms of imagination in 
 which the mind does not weave together factors of experi- 
 ence capriciously, but under the guidance of conditions 
 which limit the freedom of the constructive process. When 
 imagination is used for purposes of practical construction, 
 or for the later purposes of science, its products must be 
 subjected to critical examination by the individual who 
 develops them. A first principle of criticism of imagination 
 may be described as the principle of empirical test through 
 application. The constructs of imagination may be used to 
 guide activities, and if the activities are not successful, it 
 will obviously be necessary to go over again the combinations 
 which were worked out in consciousness and to revise these 
 combinations with a view to making them more suitable 
 bases for action. We may speak of this form of criticism 
 as the practical or empirical test of imagination. If, for 
 example, a given individual finds that he must get across 
 a certain stream, he is likely, if he has time and the neces- 
 sary mental development, to consider first in imagination 
 the means by which he can get across. He determines in 
 
IMAGINATION AND CONCEPTS 257 
 
 thought that it would be possible by bringing together 
 certain appliances to make the passage easy. If, on trying 
 the expedients which have suggested themselves in his 
 thought process, he finds that the idea is a good one, 
 his imagination receives the confirmation which comes from 
 practical utility. If, on the other hand, his imagined device 
 breaks down when put to the practical test, he will be led 
 to further considerations of a more elaborate character, in 
 order to correct the deficiences which have been shown by 
 the practical test to exist in his imagination. 
 
 Empirical test often inapplicable. There are many ideal 
 constructions which cannot be subjected directly to practical 
 tests. For example, in the course of human history man has 
 constantly been trying to reconstruct in imagination the process 
 of the development of the earth on which he lives. Our modern 
 science of geology is an elaborate effort to reconstruct the 
 history of the earth. Obviously, the ideas reached by geology 
 cannot be tested by any single practical act. Man has de- 
 veloped, accordingly, a system of criteria by which he tests 
 the validity of his ideal constructions, even when these ideal 
 constructions are not directly intended for the practical uses 
 of life. These theoretical criteria, as we may call them, can 
 be shown to grow out of the nature of experience itself. 
 
 The test of internal agreement. It is demanded by every 
 human consciousness that the elements of any given idea 
 shall be harmonious. We have seen that it is true of per- 
 ceptual processes that they have unity and arrangement, such 
 that all of the conflicting qualitative factors are provided for 
 in a single experience through the arrangement of the ele- 
 ments of experience in spatial and temporal series. Thus, 
 even in perceptual consciousness, a certain coherency and 
 harmony are required of the elements before they can enter 
 into the percept. Still more when we come to the constructs 
 of imagination is there a demand for harmony of relations 
 among the factors which are presented. Thus it would be 
 
258 PSYCHOLOGY 
 
 difficult to think of one physical substance as subject to gravity 
 and another as not. If any factor or relation is recognizably 
 incongruous with the system of experiences into which it is 
 introduced, then that system of experience will have to be 
 rearranged until the whole organization is adapted to the re- 
 ception of the element which was out of harmony with the 
 other elements, or else the incongruous element will have to 
 be rejected. Thus, if all substances fall toward the earth and 
 smoke rises, we must devise an explanation. Scientific imagi- 
 nation, when not susceptible to practical tests, is thus nothing 
 more nor less than the effort to develop an elaborate system 
 of congruous ideas. 
 
 The criterion of coherency a product of development. 
 Primitive man does not have this criterion of the harmony 
 of all of the elements of thought as fully developed as 
 does modern science. This is in part due to the limitations 
 of primitive experience : as when a savage believes thunder 
 to be a voice because he knows little of either the thunder 
 or of the mechanism which produces the voice. It is in 
 part due to a general uncritical attitude : as when in Greek 
 mythology the earth is borne upon the shoulders of Atlas 
 because attention was not ordinarily concentrated on the 
 necessity of supporting Atlas. 
 
 The demand for coherency as exhibited in constructive 
 scientific ideas. It cannot be asserted that the criterion of 
 harmony among the elements of imagination is applied with 
 full success even in modern science, but examples can be 
 given without limit of its application. Thus, it is quite im- 
 possible for us to think of the earth and the sun as related 
 to each other without, at the same time, conceiving of some 
 kind of bridge between the earth and the sun. Science has 
 therefore developed the notion of the ether as a continuous 
 substance between the earth and all other points in the uni- 
 verse. The ether is not a factor of direct experience in any 
 form. It is demanded in scientific considerations in order to 
 
IMAGINATION AND CONCEPTS 259 
 
 make the idea of the solar system and of the universe a co- 
 herent thinkable idea. Ether may, accordingly, be called a 
 product of imagination. This statement does not deal with 
 the question of its objective reality ; it merely asserts that 
 ether comes into scientific experience in response to a demand 
 for harmony in the ideational system, not through perception. 
 Uncritical imaginations. The extent to which imaginations 
 are criticized depends upon the development of the individ- 
 ual who possesses them and upon the type of ideas under 
 examination. A good illustration of the dependence of criti- 
 cism on individual development was given above in discuss- 
 ing the myths of primitive peoples. Another may be found 
 in the imaginations of children. It has frequently been said 
 that children are more imaginative than adults. This state- 
 ment is based on the observation that a child will imagine 
 many things in connection with its toys and derive a great 
 deal of satisfaction from these imaginations, when an adult 
 would be so clearly conscious of the falsity of the imagina- 
 tions that he would derive little pleasure from them. This 
 observation does not show that the child is more imaginative 
 than the adult, but it shows that the imaginations in early life 
 are not subjected to any careful criticism. Almost any men- 
 tal combination is accepted by the child and enjoyed for the 
 moment without serious criticism. Indeed, the child's experi- 
 ence is often like the savage's, too meager to make it possi- 
 ble for him to construct any systems of thought that shall 
 constitute the basis for the criticism of his particular imagi- 
 nation. Furthermore, many of the child's activities are not 
 sufficiently serious to constitute practical tests for his imagi- 
 native constructs. As life goes on and the systems of thought 
 become more and more closely united with each other, and 
 the practical demands of individual existence come to be 
 more strenuous, the indulgence in fanciful imaginations un- 
 checked by criticism becomes less common than it was in 
 early childhood. 
 
26o PSYCHOLOGY 
 
 Literary imagination and the canon of coherency. An illus- 
 tration of the way in which the products of imagination may 
 be subjected to different kinds of criticism is to be found in 
 the case of literary forms. Literature is an effort to construct 
 through the exercise of imagination a system of thought 
 which deals with human interests and human activities. If 
 this constructive process purports to be held closely in agree- 
 ment with certain records, we call it historical in character, 
 and we demand that it shall conform to the canons of con- 
 gruity with all the legitimate records of the period in question. 
 If the construction is, on the other hand, confessedly free 
 from any particular reference to definite situations, we call it 
 imaginative literature and recognize its product as fiction. 
 
 Even in this case we demand of literature that it shall have 
 
 * 
 
 relation to experience. A wholly unnatural creation has no 
 justification, even in fiction. The particular circumstances 
 which are grouped together may be circumstances which 
 never were brought together in the course of human history 
 or individual life, but the principles of combination must 
 be recognizable as principles in harmony with the general 
 nature of human experience. 
 
 The canons of criticism in literature are by no means as 
 clearly definable as are the canons of criticism in scientific 
 thought. The reason for this is that literature includes wide 
 variations in types of individual experience and consequently 
 permits laxness in the demand that the imagined experiences 
 shall conform to the particular type of any individual's life. 
 It is not difficult for us to accept certain rather grotesque and 
 unusual combinations, provided these combinations of experi- 
 ence are referred to periods in time or points in space remote 
 from those with which we are ordinarily in contact. 
 
 The uncritical forms of thought which preceded science. 
 The beginnings of what we call scientific thought are obscure, 
 because the careful comparison of scientific ideas is preceded, 
 at times by much practical adjustment of activity to the 
 
IMAGINATION AND CONCEPTS 261 
 
 environment and, at other times, by much uncritical specula- 
 tion. The practical effort to adjust one's activities to the 
 world leads to certain systems of ideas. Thus, the child 
 always looks for the causes of the happenings which come 
 into his experience long before he formulates in clear, explicit 
 thought the statement that every event has a cause. When 
 he hears a noise, he has a vague notion of something back of 
 the noise. In the same way men must have sought causes in 
 practical life long before there was any science. They also 
 had ideas which they used in the constructive activities of 
 life, such as ideas regarding the strength and durability of 
 certain building materials. In addition to these practical 
 ideas there were speculative ideas. Superstitions of all kinds 
 flourished in the uncritical thought of primitive man. If a 
 bird flew across his path, he thought of infinite varieties of 
 good or ill. There is a certain sense in which all these 
 superstitious and practical ideas constitute the beginnings 
 of science. They furnished the thought material which, 
 when sifted and organized into systematic form, constitutes 
 science. The methods for sifting and organizing this thought 
 material are the essential additions to mental life which came 
 with science. 
 
 First sciences limited to facts remote from life. When 
 the systems of coherent ideas began to emerge from the 
 original chaos of practical and superstitious constructs, it is 
 striking that the facts remote from individual control w^ere 
 the earliest to yield to the organizing endeavors of thought. 
 It was possible to construct a system of consistent scientific 
 ideas regarding celestial movements, because these remoter 
 facts were far enough* from individual life to be observed 
 without perplexing minor incongruities. The nearer facts of 
 any situation are too full of variations to fall into anything 
 like an harmonious system without the most elaborate idea- 
 tional reconstruction. Thus, a science of social relations and 
 a science of mental processes could develop only after man 
 
262 PSYCHOLOGY 
 
 had become so thoroughly devoted to the forms of scientific 
 thought that he could follow facts in long series, could 
 deliberately assume some attitude other than that of direct 
 personal relationship^ and, consequently, could trace out 
 certain abstract relations in the midst of the complex of 
 varying elements. 
 
 Scientific concepts. Let us consider one of the scientific 
 constructs built up in the course of the development of phys- 
 ical science. Such a construct is called a scientific concept. 
 An example of such a concept is that of the atom. Man 
 found, as he examined the bodies about him, that these 
 bodies underwent certain changes which were indicative of 
 unperceived characteristics. It was important to understand 
 these characteristics in dealing with the bodies for practical 
 purposes. For example, water freezes, stones crumble, metals 
 expand and contract with changes in temperature. Man must 
 have noted many of these changes and many of their condi- 
 tions very early in his dealings with such substances, but he 
 had no direct means of observing what went on in the mass 
 of the matter itself. He therefore set about, at least as far 
 back as the early Greeks, trying to form some idea of the 
 changes which must take place within the substance, in order 
 to explain the changes which he observed. Certain of the 
 Greek thinkers drew upon the forms of experience with 
 which they were familiar — namely, their experience of com- 
 posite matter made of separate parts — and formulated the 
 concept that all substances are made up of particles which 
 are separated by intervals of space. They concluded, further, 
 that the particles which they assumed as the elements of the 
 substance must be capable of greater and less separation 
 from one another, as in expansion and contraction, and also 
 that they must be capable of rearrangements, such that the 
 appearance of the whole substance is modified without de- 
 stroying the particles. Through such considerations as these, 
 some of the early scientists came ultimately to refer to the 
 
IMAGINATION AND CONCEPTS 263 
 
 smallest particles of any given substance as atoms, and to 
 describe these atoms as separated from one another by space, 
 and as constituting by their composition the observed body. 
 The physicist or chemist to-day uses this very valuable con- 
 cept in his thought about substances ; he constantly refers 
 to atoms, although he never expects that he will be able to 
 see an atom, or to test the validity of his mental construct 
 by the sense of touch. Indeed, the atom is an idea needed 
 by science just because science has to bring together into 
 an harmonious ideal system more than can be discovered in 
 any single inspection or handling of an object. 
 
 Validity of concepts. When such statements as these are 
 made, some persons think that the validity of the scientific 
 concept is seriously called in question. On the contrary, 
 there is no higher guarantee for any form of knowledge 
 than that it is demanded in order to render congruous the 
 whole system of experience. As we have seen, in all of the 
 earlier discussions of perception and ideation, experience has 
 many higher phases which cannot be resolved into direct 
 sensory elements. The validity of space as a form of ex- 
 perience cannot be called in question because it is a relational 
 rather than* a sensational phase of experience. For similar 
 reasons, the construction of a concept is justified as a result 
 of a higher organization of experience. The method of arriv- 
 ing at such an ideal construct is indeed indirect ; but the 
 concept has all of the validity which belongs to experience 
 as an organized system. 
 
 Abstraction. When ideas are completely under the con- 
 trol of the individual, they may be arranged according to 
 principles which are set up by thought itself. Thus, one 
 may decide that it is desirable to group together all round 
 objects or all hollow objects. There then arises an idea of 
 roundness or of hollowness which is called an abstract idea. 
 The term ''abstract" means that something has been ''cut 
 off." When we think of roundness alone, we neglect color 
 
264 PSYCHOLOGY 
 
 and position and weight. We can cut off the one quaHty 
 and make it a subject of attention because the power of 
 thought has been developed to the point where inner motives 
 are stronger than external motives. 
 
 Generalization. Furthermore, whenever the mind reaches 
 the stage where it can select and concentrate on single as- 
 pects or attributes of experience, it can at the same time 
 group together under each selected attribute many individual 
 cases. This is called the power of generalization. Thus, 
 once the mind has fixed on roundness as a selected attribute 
 of objects, it can bring together and group in one class the 
 earth, a ball, an apple, etc. 
 
 Abstraction and generalization are valuable not merely as 
 feats of inner control ; they make possible highly developed 
 forms of conduct. If one can select and hold steadily be- 
 fore the mind one aspect of an object, conduct can be made 
 more effective through concentration than when the observer 
 is distracted and confused by an effort to deal with unanalyzed 
 complexity. 
 
 We shall find ourselves coming back to this topic later 
 when we take up volition as the highest form of behavior. 
 The more fully ideas are abstracted and generalized, the 
 more conduct will be guided by inner motives. The man 
 who sees values in objects and decides to be thrifty is guided 
 by an abstraction and is so far forth acting in response to 
 an inner motive. 
 
 Judgments and reasoning. After a concept has been for- 
 mulated, it may become part of a still more complex mental 
 process which includes several ideas. Thus, when two con- 
 cepts are related as in the statement '' The sun is the center 
 of the solar system," the whole process is termed a judgment. 
 When two or more judgments are united for the purpose 
 of setting up an even more complex combination, the whole 
 process is called reasoning. An examiple of reasoning is as 
 follows: The sun is the center of the solar system; any 
 
IMAGINATION AND CONCEPTS 265 
 
 central body in a system of this type must have a control- 
 Hng influence over the other members of the system ; hence 
 we should look for the control of the sun over the earth and 
 the other planets. 
 
 Logic. It is not in place here to give an account of the 
 various types of judgment and reasoning. It is the function 
 of the science of logic to study the complex processes of 
 thought and to develop the rules under which the validity 
 of these processes may be tested. We must content our- 
 selves in an introductory treatment such as this with certain 
 comments which will serve to call attention to the psycho- 
 logical character of these complex forms of ideational experi- 
 ence. Perhaps the best single topic with which to introdupe 
 a psychology of logic is the topic of belief. Let us consider, 
 therefore, what is meant by the statement '' I believe a 
 certain conclusion to be true." 
 
 Primitive belief. The first and most direct case of belief 
 is that in which I assent to any combination of ideas be- 
 cause my natural tendency is to accept combinations of ideas 
 when there is no reason to deny what is presented. The 
 psychological fact is that ideas which stand together in the 
 mind unchallenged by other experiences are accepted as 
 coherent and acceptable. Thus, when I was a child I be- 
 lieved in Jack the Giant Killer and Jack and the Bean Stalk 
 because my experience was too limited to deny these stories. 
 
 Belief after hesitation. A higher form of belief comes 
 after one has hesitated. In such cases the statements are 
 not immediately accepted. This means that they arouse 
 series of associations which suggest various conflicting forms 
 of statement. At this stage there is a restlessness, and other 
 forms of statement are tried ; other authorities are cited. It 
 may be that one goes out and tests the conclusion by practi- 
 cal behavior. If the first opposition is broken down by one 
 or the other of these influences, there results in the end a 
 waning of the suggested contradictions. 
 
266 PSYCHOLOGY 
 
 Belief a positive psychological fact. 'jThere can be no 
 doubt that belief in all these cases is something more than 
 the mere hearing of certain sounds or the mere coupling 
 together of certain ideas. When we say that the idea is 
 accepted, we undoubtedly refer to some positive physiolog- 
 ical process. Belief is related to the fact that a sensory 
 impression goes through the nervous system to some form 
 of positive expression without being opposed. If it were 
 checked by encountering some current opposing it, we 
 should be restless and the feeling would be one of hesita- 
 tion. Assent is a genuine process of a positive type. Such 
 a positive process will usually issue in a definite motor re- 
 sponse. It may be that the motor process is a mere nod 
 of the head or an inner emotional twinge. The important 
 fact is that the nervous process issues in a positive dis- 
 charge. The motor discharge may be in itself insignificant, 
 but the fact that it occurs and the fact that it is positive 
 in character give to experience that special turn or coloring 
 which we designate by the term '' belief." 
 
 Spurious verbal belief. Such considerations lead to brief 
 comment on what is called mere verbal assent. It is possi- 
 ble for one to give assent carelessly by merely repeating 
 what he hears. Many students accept what they find in 
 books in this way. The motor paths leading to the speech 
 centers seem to be stimulated directly by the eyes as they 
 read, or by the ears as they hear. Reaction is of little value 
 in such cases. It is a kind of shunt circuit. The impres- 
 sion does not get mixed in the association areas with any 
 forms of ideation which confuse or interrupt the direct 
 transmission to the speech center. The result is a specious 
 belief and a useless form of nervous and mental reaction. 
 There is nothing more fatal to true mental organization 
 than this short-circuiting of the eyes and ears to the vocal 
 centers. It is one of the penalties which man pays for the 
 development of an indirect mode of behavior. 
 
IMAGINATION AND CONCEPTS 267 
 
 Habitual belief. Another highly developed form of belief 
 is that which comes from the organization in individual life 
 of certain habitual modes of response. Thus the physicist 
 learns, in spite of sensory testimony to the contrary, to 
 think of every substance as porous. He finds that his be- 
 liefs are all conditioned by conformity to this cultivated 
 idea. If any remark is made or any fact turns up which 
 runs counter to this accepted principle, the new proposal 
 wall be rejected. Beliefs are thus not unlike the funda- 
 mental emotional attitudes. They are very real factors in 
 thought, though they are not made up of memory images. 
 
 Religious belief not instinctive. Certain wTiters, im- 
 pressed with the similarity of beliefs to emotional attitudes, 
 have regarded certain w^ell-established beliefs, such as reli- 
 gious beliefs, as instinctive." The belief in the Deity, in im- 
 mortality, in the certainty of moral categories, is held by 
 these authors to be no less primitive in human nature than 
 the fundamental desire for food, for physical comfort, and for 
 companionship. On the other hand, it is held by others that 
 such beliefs are the results of developed systems of ideas. 
 
 Sentiments not instinctive. The latter formula, which is 
 the more defensible, suggests the explanation of many of 
 the so-called sentiments and tastes of later life. They are 
 connected with acquired modes of behavior. Certainly, if 
 one studies the life and practices of savages, he finds a 
 striking parallelism between behavior and tribal belief. The 
 savage practices certain customs, and they come to have for 
 him the sanction of the highest religious demands. So in 
 civilized life as well. The sanctions of society are bred into 
 our very beings until we believe in the necessity of social 
 conformity. 
 
 Social life and the higher mental processes. Efforts have 
 been made in the recent literature of sociology and psychol- 
 ogy to explain social institutions as the products of instinc- 
 tive tendencies. The argument of this chapter is that belief 
 
268 PSYCHOLOGY 
 
 which grows out of systematic thinking, while it may have 
 the appearance of an instinctive emotion, is in reahty the 
 product of the highest types of mental activity. Social 
 sanctions are evolved through association and comparisons 
 of ideas and through the evolution of modes of social be- 
 havior. Society may rest on instinctive tendencies, but its 
 forms and operations are all worked out through the use of 
 language. Everywhere in social life one finds abstractions, 
 now of a higher type, now of a lower. Social life is a proa- 
 uct of thought and ideation, not of blind instinct. 
 
 Fields for the application of psychology of ideas. This 
 chapter must close with these mere outlines of discussions 
 of the higher mental life. That there is a field for a psy- 
 chological study of all the higher forms of appreciation is 
 indicated by what has been said. This matter will be 
 touched on again in a later chapter dealing with the appli- 
 cations of psychology. 
 
 There is a psychology of invention in which the indi- 
 vidual is studied at those critical moments when a new set 
 of associations is being evolved within him. There is a 
 psychology of education which must distinguish between 
 learning of a true type and learning to repeat words out of 
 books. There is a psychology of social theory and social 
 conduct. The formula for all of these is a formula of organ- 
 ized mental processes leading to various forms of expres- 
 sion. If the student has grasped the import of this general 
 formula, he will be able to unravel the particular types of 
 organization which appear in each of these spheres. 
 
CHAPTER XIII 
 
 THE IDEA OF THE SELF 
 
 The idea of self sometimes regarded as matter of direct 
 knowledge. Among the ideas which are built up in practical 
 life and refined by scientific study, there is one which is of 
 special significance to the student of psychology. It is the 
 idea which each person has of himself. So significant is 
 this idea for. our ordinary thought that it has sometimes 
 been described in terms which imply that one knows one- 
 self directly as though through some kind of immediate per- 
 ception. One is supposed to look within and there find an 
 inner reality which is known and recognized without any of 
 the ordinary steps that enter into the process of knowing 
 reality. 
 
 Idea of self a concept. That the self is a being which 
 can be directly perceived is, however, contradicted by all the 
 facts of development. The child does not know himself 
 until after he has had a series of experiences. Even the 
 adult has something to learn about himself with each new 
 turn of conscious life. The idea of self must therefore be 
 described as a concept which matures in the course of ex- 
 perience just as does any other scientific or practical idea. 
 
 First stages of personal development not self-conscious. 
 Let us attempt to formulate what we know of the most 
 primitive stages of experience, in order that we may arrive 
 at some notion of what consciousness is like before there is 
 any recognition of the self. The simplest forms of animal 
 behavior, as has been repeatedly pointed out, do not indicate 
 any clear marking off of impression from expression. The 
 
 269 
 
270 PSYCHOLOGY 
 
 activity which follows upon impression is so direct that there 
 is no time for the interpolation of any factor, either in the 
 nervous system or in consciousness, between impression and 
 expression. Much the same kind of situation appears when 
 we examine the human infant. There is an inherited mech- 
 anism in the instincts which supplies appropriate responses 
 to stimuli, and as a result there is little or no consciousness 
 of any kind involved in reacting to the impression — cer- 
 tainly no recognition of one's own personality. Sensation 
 and response blend in an experience which is overwhelm- 
 ingly emotional in character and not at all capable of dis- 
 tinguishing one factor of the situation from another. Such 
 experience includes no separate idea of oneself. 
 
 Gradual discrimination of self from things. The develop- 
 ment from this point is toward the discrimination of phases 
 of experience. Probably there is a gradual differentiation of 
 the sensory elements from one another and of the sensory 
 elements from the individual's attitudes and responses. As 
 soon as things begin to be recognized, there must be a 
 tendency to formulate all one's feelings and attitudes into 
 a kind of personal unity or self. The construction of such 
 a personal core or self in contrast with things is a slow and 
 complex process. 
 
 Child's early notion of self largely objective. Undoubt- 
 edly, a child's contact vs^ith his own body is very important 
 in building up some early crude distinctions between im- 
 pressions and attitudes. When the child handles his own 
 feet, he finds that the impression he receives, and the atti- 
 tudes into which he is thrown by the double stimulation of 
 two parts of his body, are entirely different from the impres- 
 sions which he receives and the simpler attitudes into which 
 he is thrown by the stimulation of one of his members 
 through some external object. He thus comes to distinguish 
 between his body and the external world. The body is a 
 part of the world with characteristics different from the 
 
THE IDEA OF THE SELF 271 
 
 other factors which he recognizes through his senses. There 
 is probably some ground in this fact for the statement that 
 the child's earliest recognition of himself is of the nature of 
 a percept and relates to his physical organism. The rela- 
 tively objective character of the experience of self at this 
 stage is shown by the fact that, in addition to his own body, 
 the child attaches to himself, as a part of what he calls him- 
 self, the possessions which he comes to recognize as his 
 individual property. The external world is broken up into the 
 nteutn and tuum^ and the general notion of that which belongs 
 to the individual himself is gradually distinguished from that 
 which belongs to others, but the meum is not primarily a sub- 
 jective fact. It is looked at through consciousness, but that 
 consciousness is very little self-consciousness in the purely 
 subjective sense in which we use that term in mature life. 
 
 The idea of self as related to discrimination between the 
 objective and subjective. Such considerations as these tend 
 to show that the idea of self is a product of discrimina- 
 tive analysis rather than a fact of immediate perceptual 
 consciousness. So far as we understand immediate con- 
 sciousness in its early stages, there appears to be little or 
 no ground for assuming that there is present any complete 
 discrimination of the self on the one hand and things on 
 the other. Even in mature life the distinction between the 
 self and nonself is not always drawn. The man who is 
 hurrying to catch a street car has a vivid experience, but 
 it is not nicely analyzed. The hungry man with food before 
 him is little more self-conscious, if, indeed, any more self- 
 conscious, than the animal which spends all of its time and 
 energy in the eager pursuit of food. 
 
 The self discovered by contrast with not-self. What 
 brings any individual to a clear recognition of himself will 
 probably depend upon the accidents of individual fortune. 
 The struggle of personal interests with some unyielding 
 objective fact may accomplish it. The development of an 
 
272 PSYCHOLOGY 
 
 idea of some other self, opposed in interest to the self, is 
 often a powerful incentive to the recognition of one's own 
 self. Historically, it has repeatedly been pointed out that 
 the national spirit, which is analogous to personal self- 
 consciousness, often grows out of some contest. In like 
 fashion, the clear idea of the self undoubtedly rises out of 
 some contest of opposing interests. 
 
 Social consciousness and self-consciousness. The conflict 
 of interests may take a purely social form, as in the use of 
 language. One sees that all the words referring to spatial 
 directions, for example, center about one's own body. One 
 finds that active or passive verbs have reference to some 
 person. One finds, in short, that one's own expressions are 
 arranged and organized around a different center than are 
 the expressions of every other human being. So impressive 
 does this contrast between individual attitudes become that 
 ultimately, when we find ourselves in agreement with others, 
 we are impressed with the agreement, as in earlier cases we 
 were impressed by the differences, in mental attitude. The 
 result is that our contact with the social world is a constant 
 stimulus to the development of a more and more clearly 
 defined recognition of the self. The child undoubtedly 
 comes to self-consciousness through his use of language 
 more than through any other means. 
 
 The self at first not a scientific concept, but a practical 
 concept. Some idea of the self, based upon discrimination 
 of one's own attitudes from the attitudes of other persons, 
 is developed in a wholly unscientifixC way by every individual, 
 just as the discrimination of the individual body and of 
 one's personal possessions from the rest of the physical 
 world arises naturally in the course of personal life without 
 any effort at systematic definition. Beyond this natural dis- 
 crimination one may attempt to cultivate a more highly 
 refined formulation of his personal attitudes and personal 
 characteristics, and yet not pass directly into science. 
 
THE IDEA OF THE SELF 273 
 
 Cultivated self -consciousness. To illustrate certain cases 
 in which self-consciousness takes a form other than the 
 scientific, we may refer first to literary criticism. If a 
 reader begins the criticism of any piece of literature, he 
 will constantly be contrasting the impression which the 
 author intended to produce with the personal attitude 
 aroused in himself through the statements which he reads. 
 There will thus be a certain social contrast between the 
 individual and the author, and this is deliberately cultivated 
 for the purpose of refining and critically elaborating one's 
 own taste. In some cases this may take the form of an 
 effort to conform personal tastes or attitudes to the stand- 
 ards which have evidently been adopted by great masters. 
 There is here an unquestionable tendency to refine self- 
 consciousness at the same time that one cultivates attitudes 
 toward the objective facts. 
 
 The religious motive for self -consciousness. Another 
 illustration of the nonscientific cultivation of the concept 
 of the self will appear if we refer to the attitude which is 
 assumed by many individuals in the contemplation of their 
 own origin and destiny. The religious attitude has un- 
 doubtedly contributed more to the definition of self in the 
 minds of unscientific individuals than any other system of 
 thought or activity in the world's history. One here asks 
 himself how fully his own personal attitudes conform to 
 what he understands to be the demands of the laws gov- 
 erning his destiny. The system of laws, which he accepts 
 as a system of higher law, may be derived from very dif- 
 ferent sources ; but in any case, whether it be the religious 
 faith of the savage or the systematized theology of the 
 most highly cultivated devotee of an elaborate religious 
 system, there is always in religious thought and aspiration a 
 comparison between the demands of the religious system and 
 the demands of individual interest and feeling. The notion 
 of the self comes to have a compactness and importance 
 
274 PSYCHOLOGY 
 
 under this system of religious self-examination which it 
 could never attain by mere social contrast with the experi- 
 ences of other individuals or in the presence of physical 
 objects. Questions of ultimate destiny arise, and these 
 are answered in terms of a self which is much more 
 highly elaborated than the bodily or material self upon 
 which man concentrates his attention in the early stages 
 of individual life or the primitive stages of mental develop- 
 ment. We find, however, many indications, as we look 
 into savage customs, of a curious mixture of the primitive 
 bodily self and the religious self. The savage always pro- 
 tects with great care the bodily remains of those whom he 
 would serve, and he mutilates and destroys the body of an 
 enemy. The bodily self is here recognized as the tangible 
 aspect of personality. 
 
 Scientific idea of personality. As contrasted with these 
 unsystematic efforts at self-realization, the science of psy- 
 chology aims to build up a thorough idea of the nature 
 and relations of the self. The self becomes for our science 
 a being whose laws of organized life must be discovered 
 and explained. 
 
 The self can be fully described and understood only 
 through studies of the type which have been outlined in 
 the foregoing chapters. The self is a being which per- 
 ceives and forms concepts ; it remembers and expresses 
 itself in regular habits. It is characterized by emotions 
 and by elaborate ideational forms of thought. The self is, 
 however, not merely a chance collection of percepts and 
 habits and ideas. There is one attribute of the conscious 
 self which stands out as of paramount importance. The 
 self is a unity. It expresses itself now in one direction, 
 now in another, but in all its various manifestations it is 
 an organized unit. Whatever conscious states the self pos- 
 sesses are modified by virtue of the fact that all aspects 
 of individual consciousness are united in the one being. 
 
THE IDEA OF THE SELF 275 
 
 The only analogy which can be used in expounding this 
 type of being is the analogy of life. The living being is 
 an organized unity. 
 
 The chief item in the concept of life the abstract idea 
 of organization. Such statements as the foregoing are con- 
 fusing to certain students of science. They profess to 
 know what an atom or an object is, but they say of life 
 that it is not a scientific entity because it is not simple, 
 and they say of conscious selves that they are not entities 
 in any such scientific sense as are atoms and physical 
 forces. Some chemists, for example, would reduce life to 
 mere coexistence of atoms in a complex molecule of pro- 
 toplasm. It is, indeed, true that there is a chemistry of 
 protoplasm. The significant fact, however, is that once 
 the molecule of protoplasm became organized it began to 
 exercise functions which were absolutely new. It began 
 to reproduce, to contract, to show irritability, and to take 
 in foreign particles and transform them into new molecules 
 of protoplasm. The world began to take on a new aspect 
 when protoplasm came into it. One cannot continually 
 look backward to chemical elements in treating of pro- 
 toplasm ; he must look forward to the effects produced 
 by protoplasm. 
 
 Unity of self. So it is with a conscious being. Such 
 a being is conditioned by sense organs and central nervous 
 processes, but a description of these conditions does not 
 exhaust the account. The self has become through organi- 
 zation a unit in the world, capable of affecting in some 
 measure the doings of this world. 
 
 The self as an efficient cause. A conscious being is, ac- 
 cordingly, different from a being not endowed with mind just 
 in the degree in which the conscious being can produce 
 effects which depend on consciousness. To deny the reality 
 of the conscious self is to repudiate a scientific concept which 
 is as fully justified as the concept solar system. 
 
2^6 PSYCHOLOGY 
 
 Self as a valid scientific concept. Yet certain writers 
 deny the right of science to deal with the idea of self. 
 They say that the self is never seen as is the object which 
 gives us a visual impression. They say that physical reality 
 can be known, but the knowing self is something intangible 
 and unapproachable by scientific methods. The difficulty in 
 the whole situation is that the individual who is trying to 
 explain and understand himself sometimes loses sight of 
 the central fact of his own mental life, as he explores the 
 conditions which surround this central personality. The 
 central personality is' taken so much for granted that sci- 
 entific description tends to deal with all that leads up to 
 personality, and there it stops, finding its chief subjects 
 of thought in these surrounding facts rather than in the 
 central result of all the organized conditions. Some day 
 the historian of thought will write it down as one of the 
 curious fallacies of immature science that certain physiol- 
 ogists, biologists, and even psychologists, were satisfied to 
 call their own personalities mere by-products, without es- 
 sential significance in the world, just because they did not 
 find consciousness capable of description in the regular scien- 
 tific formulas adopted for the discussion and explanation of 
 external reality. 
 
 One hardly knows how to find phrases in which to 
 answer those who hold consciousness to be less real and 
 potent than physical forces. Certainly, nature has protected 
 and conserved consciousness throughout the whole develop- 
 ment of the animal kingdom. Certainly, the world is dif- 
 ferent because consciousness has been evolved. Certainly, 
 consciousness is no less real than are its conditions ; and, 
 finally, consciousness is certainly much more directly 
 approachable to the student of science than is matter. 
 
 Concept of unity. These are the statements which de- 
 scribe the psychologist's concept of the self. Such a con- 
 cept is no less clear and well established than the concepts 
 
THE IDEA OF THE SELF 277 
 
 of all science. Indeed, it is from one's own ideas of him- 
 self that the notion of external unities is derived. When 
 one comes back time and time again to the same object and 
 recognizes it as familiar and attributes to it a continuity 
 which goes far beyond anything he can observe through his 
 senses, he is projecting a concept of unity derived from his 
 own experience into the world of outer realities. When sci- 
 ence thinks of the earth as a unity, or of the universe as a 
 unity, this is a concept, not a percept. The same kind of 
 comprehensive generalization appears in the practical and 
 scientific study of self. It is probably not true that animals 
 recognize their ow^n unity. Experience with them is, as it 
 is with us, a succession of interrelated events, but the sur- 
 vey of the total succession is not possible in the undeveloped 
 animal consciousness. It is probably not true that children 
 have any broad view of the unity of their personalities. The 
 ability to remember is one of the most significant special 
 experiences from which we derive the content with which to 
 construct a broader self. The ultimate recognition of the most 
 comprehensive unity is a conceptual rather than perceptual 
 fact, even after memory has made its full contribution. 
 
 The self a concept. One must be satisfied with a scien- 
 tific description of the self. One can never see the self 
 directly. To demand that the details of the total unity be 
 filled in with a concrete image or illustration is to demand 
 even more than natural science would demand, if it required 
 a direct perceptual representation of its ultimate substances, 
 such as the atoms. 
 
CHAPTER XIV 
 
 DISSOCIATION 
 
 Disorganized personality in contrast with normal self. 
 
 The discussions of the last chapter, as well as the detailed 
 description of mental processes of various types, show how 
 essential is the concept of self unity. This lesson is power- 
 fully reenforced by considering certain abnormal states in 
 which the unitary self gives way to disintegrating forces and 
 leaves the self broken down and unable to play its part in 
 the world. 
 
 Illusions and hallucinations. Every form of mental pa- 
 thology or abnormality is in some sense a case of malorgani- 
 zation or disintegration. There are certain mild cases of 
 irregularity which may be classed as forms of maladaptation, 
 rather than distinctly pathological cases. Such are, for ex- 
 ample, our geometrical illusions. As we saw in our earlier 
 discussions, an illusion is always an incomplete organization 
 of the sensations presented to the observer. Defects in or- 
 ganization may be carried very much further in the case of 
 a person who has what are known as hallucinations. An 
 individual may, for example, have an irritation upon some 
 part of the skin which, under normal conditions, would be 
 neglected or, at most, treated as an inconvenient excitation 
 of the part ; but if the organizations of mental life are un- 
 stable because of some general diseased condition of the 
 individual, this excitation in a certain part of the skin may 
 become the center for a most abnormal combination of ex- 
 periences and may lead to the development of a distinctly 
 abnormal type of interpretation. Everything that suggests 
 
 278 
 
DISSOCIATION 279 
 
 itself to the mind may be made subservient to this stimula- 
 tion, until finally the person constructs an imaginary world, 
 giving the abnormal excitation a value and importance which, 
 in normal life, it could never have had. He may come to 
 believe that he is made of glass or stone, or he may think 
 that someone is attacking him with poisons or acids. These 
 illustrations will serve to make clear what is meant by the 
 statement that abnormal mental experiences are always ex- 
 periences which result from irregularities in organization, 
 and commonly involve more or less disorganization or dis- 
 sociation of the elements which should be combined. 
 
 Sleep, the influence of drugs, hypnosis, and insanity as 
 forms of disorganization. We may examine three distinct 
 cases of dissociation in order to make clear in detail what 
 is meant by mental disorganization. First, there is in sleep 
 a form of normal suspension of central nervous activity which 
 has been provided by nature for the purpose of recuperating 
 the individual. This nervous condition is accompanied by a 
 temporary interruption of normal conscious processes. Sec- 
 ond, there are certain forms of dissociation and partial re- 
 construction which are very similar in character to sleep, but 
 do not serve the purposes of recuperation as does normal 
 sleep. The conditions here referred to may be induced by 
 the use of drugs or by certain other devices, conspicuous 
 among which are the methods of inducing hypnosis. Finally, 
 the dissociations and "partial reconstructions, which are tem- 
 porary in hypnosis and after the use of certain drugs, may 
 appear in a great variety of relatively permanent forms in 
 the different types of insanity. One or two of these typical 
 forms of insanity will be referred to later, in order to 
 exemplify the conditions which result from permanent 
 disorganization. 
 
 The physiological conditions of sleep. The physiological 
 conditions which present themselves in the nervous system 
 during sleep are not fully understood, but their general 
 
28o 
 
 PSYCHOLOGY 
 
 character can be described with sufificient clearness for our 
 purposes. In the first place, the condition of fatigue in the 
 nerve cell has been found to be a condition of somewhat 
 depleted tissue in the cell body. There are also certain 
 chemical changes resulting from fatigue. These are demon- 
 strated by the different degrees 
 to which fatigued and normal 
 cells respectively take on the 
 coloring substances which are 
 used in staining microscopic 
 sections of the tissue. The 
 protoplasm of the fatigued 
 cells, as seen from Fig. 58, is 
 in part exhausted as a result 
 of the processes of stimulation 
 through which they have passed. 
 Sleep must be a condition in 
 which these cells are supplied 
 with nutrition and return to 
 their normal state of energy 
 and activity. During the period 
 of sleep, each cell seems to be 
 capable of insulating itself from 
 the neighboring parts of the 
 nervous system. There are 
 some extreme conditions, prob- 
 ably pathological in character, 
 in which the dendrites of the 
 nerve cells curl up and form, 
 instead of extending branches, little knotty balls across 
 which stimulations cannot easily pass. This curling up of 
 the dendrites is probably a very much more radical change 
 than occurs under the ordinary conditions of sleep. The 
 synapses, or interlacing of fibers, which connect a cell 
 with other cells or incoming fibers, are interrupted in most 
 
 Fig. 58. Fatigued cells 
 
 Two sections A and B from the first 
 thoracic spinal ganglion of a cat. B is 
 from the ganglion which has been elec- 
 trically stimulated through its nerve 
 for five hours. A is from a correspond- 
 ing resting ganglion. The nuclei N of 
 the fatigued cells are seen to take a 
 darker stain and to be very irregular 
 in outline. The general protoplasm of 
 the cell bodies is also less uniform in 
 density in the fatigued cells. (After 
 Hodge) 
 
DISSOCIATION 281 
 
 cases, not by any gross movement of the dendrites but rather 
 by some chemical change in the tissue which makes it 
 difficult for the stimulation to pass across from one cell to 
 another. There are known chemical substances which affect 
 primarily the synapses and prevent stimulations from being 
 transmitted from cell to cell. All of these indications go to 
 show that the nerve cell, when it enters on the process of 
 recuperation, tends to give up its normal transmitting func- 
 tion, and devotes itself for the time being to the processes 
 of building up tissue. 
 
 The closing of avenues of stimulation in sleep. The ex- 
 ternal characteristics of a sleeping individual are clearly 
 intelligible in terms of the physiological changes which have 
 been described. In the first place, the individual becomes 
 less and less susceptible to stimulations from the outside 
 world. This means that w^hen any form of external energy 
 acts on the nervous system, it finds the nervous system rela- 
 tively inert. The receiving organs are closed and their cells 
 are probably in a chemical condition unfavorable to any vig- 
 orous activity. Even when stimulations are received at the 
 periphery and are transmitted to the central nervous system, 
 they make headway through the tissues with the greatest 
 difficulty. They do not follow the well-defined paths which 
 are used in normal life, but are diffused throughout the 
 whole organ. 
 
 Various degrees of dissociation. The condition of the 
 individual need not be a condition of complete sleep in 
 order to show this inertness of the nervous system. There 
 are many conditions of fatigue in which the nervous system 
 shows, before sleep sets in, more or less of a tendency to 
 resist external stimulation. Furthermore, the different stages 
 of sleep are by no means equal in their degree of dissocia- 
 tion. This has been shown by experiments in which the 
 amount of noise necessary to arouse a sleeping individual 
 has been made the measure of the intensity of sleep. The 
 
282 
 
 PSYCHOLOGY 
 
 result of such experiments is to show that a person goes to 
 sleep rapidly and profoundly during the early part of the 
 night, and from this time on gradually comes back to a con- 
 dition of susceptibility to stimulation. Fig. 59 shows a sleep 
 cur\'e of the kind which results from these experiments. 
 
 800 
 
 roo 
 
 600 
 500 
 400 
 
 300 
 200 
 
 100 
 
 
 'A ' 
 
 
 
 i \' 
 
 
 
 
 
 
 - 1 \ 1 
 
 
 
 
 / \ ' ^ 
 
 
 /' V 
 
 
 
 
 -/ 1 \ ' ' 
 
 
 7 ' \ i 
 
 
 
 
 r 1 1 i ^^^^ ■ 
 
 Hours 0.5 1.0 1.5 ^.0 2.5 3.0 3.0 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 7. 
 
 Fig. 59. Curve showing the intensity of sound necessary to awaken a 
 sleeper at different periods of sleep 
 
 Along the horizontal line are represented the hours of sleep ; along the vertical, the 
 relative intensities of sound. Thus, at the end of the first ?ialf hour an intensit}' of 
 sound somewhat over six hundred is necessar\^ to awaken the sleeper. At the end 
 of two hours the intensity of sound is approximately one hundred. The cun-e indi- 
 cates that the sleeper falls rapidly into a profound sleep and then gradually comes 
 into a condition of ver\' light slumber preceding for a long time the waking. (After 
 
 Kohlschiitter) 
 
 « 
 
 The cur\"e rises rapidly, indicating, as stated, that the amount 
 of stimulation necessar}' to arouse the nerV'Ous system in- 
 creases rapidly in the early hours of sleep; it falls off 
 gradually toward the end, indicating a gradual waking of 
 the subject. 
 
 Dissociation in the central processes. Not only are the 
 cells of the sleeper's nen'ous system imper\dous to external 
 stimulation, but they are uncoupled in such a way that the 
 stimulations which succeed in entering the nerv^ous system 
 
DISSOCIATION 283 
 
 do not follow the ordinary paths of discharge. This uncoup- 
 ling of the central nerve cells does not take place in equal 
 degree in all parts of the nervous system. The large cells 
 of the spinal cord are able to resist the effects of fatigue, 
 and the spinal cord may be said never to sleep under normal 
 conditions. For this reason, stimulations which reach the 
 spinal cord from the surface of the body are always trans- 
 formed into reflex impulses and sent to the muscles of the 
 trunk and limbs. The spinal cord is in this case uncoupled, 
 not within itself, but only with reference to the higher centers. 
 The reflexes are very much simpler in form and more likely 
 to appear under these conditions than when the stimulus has 
 an open path to the higher centers. Thus a cold or uncom- 
 fortable hand will always be moved reflexly in sleep. The 
 medulla, like the cord, seems to be able to resist, to a great 
 extent, the tendencies toward fatigue, for many of the organic 
 processes, such as circulation and respiration, are maintained 
 through the nerv^e centers in the medulla, while the rest of 
 the nervous system is closed to external stimulation and to 
 any well-ordered activities. 
 
 Dreams as dissociated groups of ideas. One effect of the 
 uncoupling of the various ner\'e tracts in the organs of the 
 central nervous system above the medulla is that any proc- 
 esses which take place in these higher organs because of 
 strong stimulations, or because of some abnormal excita- 
 bility in the nen^ous system, are fleeting and irregular. The 
 higher centers probably do not all of them sink into the 
 same deo:ree of inactivitv even in a normal individual, and 
 the slightest abnormality may result in a heightened acti\ity 
 in certain parts. The facts of consciousness which corre- 
 spond to these irregular, detached activities in the central 
 nervous system during sleep are easily understood w'hen it 
 is recognized that the ner^'ous system is acting not as a 
 single organized system but as a disorganized group of 
 centers. To put the matter in terms of experience, one may 
 
284 PSYCHOLOGY 
 
 say that an idea which presents itself during sleep is not 
 related to the general body of ideas by which the experi- 
 ences of ordinary life are checked and held under criticism. 
 If, in ordinary life, the idea suggests itself to some indi- 
 vidual that he has enormous possessions, he is immediately 
 reminded by the evidences of his senses and by the familiar 
 surroundings and limitations of his sphere of action that the 
 idea is merely a subjective imagination. If, on the other 
 hand, one should have this idea in his dreams, under con- 
 ditions which would remove it from all restricting relations, 
 it would obviously be compelling in its force and would be 
 accepted by consciousness as an unqualified and unlimited 
 truth. It would be dissociated from the other ideas which 
 fill normal consciousness, and ti *s dissociation would deter- 
 mine its character in such a way as to make it distinctly 
 different from the processes of coherent thought built up in 
 normal life. 
 
 Dreams impressive only because they are uncriticized. 
 It will be seen from such considerations as these that a 
 mature individual is brought in his sleep into a condition 
 somewhat similar to that exhibited in the irregular and un- 
 restrained imaginings of children. The young child con- 
 structs imaginations and is quite unable to criticize them 
 because of his lack of experience and because of the lack of 
 organization within his experience. The lines of organiza- 
 tion are not laid down in the child; in the dreaming adult, 
 though systems of ideas have been built up, they are for 
 the time being interrupted, and the processes of mental life 
 lapse into unsystematic and uncritical forms. There is, for 
 this reason, a certain freedom from all kinds of restraint, 
 which accounts for the highly erratic character of dreams. 
 
 Motor processes suspended by dissociations in sleep. The 
 third characteristic of sleep follows naturally from these 
 which we have been discussing. Muscular movements are 
 almost completely suspended in normal sleep. The muscles, 
 
DISSOCIATION 285 
 
 relax more than they do in any condition of waking life, just 
 because the nervous system sends only very much reduced 
 stimulations to the muscles, and, as we have repeatedly 
 seen, the muscles are quite unable to perform their work 
 when they are not stimulated by the nerves. The few 
 straggling stimulations which succeed in getting through 
 the nervous system to the muscles are lower reflexes or they 
 are irregular and without coordination. The movements 
 which appear are, therefore, often more incoherent than the 
 fleeting dream experiences which accompany the activities 
 in the central nervous organs. Indeed, in most cases, any 
 intense movements of the muscles during sleep indicate a 
 distinctly abnormal condition and are closely related in char- 
 acter to the irregular coordinations which appear in certain 
 forms of drug poisoning. 
 
 Narcotic drugs dissociative in their effects. The discus- 
 sion of the phenomena which attend the use of drugs will 
 aid in the understanding of what has been said about sleep. 
 It is a familiar fact that certain narcotics produce a condi- 
 tion very closely related to sleep. The narcotic drug closes 
 the avenues of sensory reception, reduces central activity or 
 renders its processes irregular and incoherent, and suspends 
 muscular contraction. If the drug is taken in a relatively 
 small dose, so that its effect upon the nervous system is 
 slight, these various effects may be produced in slight 
 degree only. The effect in this case will be most marked 
 in the irregularity of ideas and in the incoordination of 
 the movements. 
 
 Effect of alcohol on the nervous system. A familiar effect 
 of a drug is the intoxication which is produced by alcohol. 
 The chemical condition of nerve cells and consequently the 
 relations between them are in some way affected by alcohol, 
 and the stimulations are interrupted or become irregular 
 in their transmission through the tissues. The fact that a 
 man under the influence of alcohol sees things moving 
 
286 PSYCHOLOGY 
 
 irregularly, or sees them double, depends upon the incoordina- 
 tion of the muscles of the eyes. The fact that he is unable 
 to walk steadily shows the incoordination of the muscles of 
 the legs. There is a corresponding irregularity in the flow of 
 his ideas ; and his credulousness for the ideas which suggest 
 themselves to him is analogous to the ordinary credulous- 
 ness of a dreaming sleeper. The imperviousness of such to 
 individual to the stimulations of the outside world is also 
 a well-known fact. 
 
 Overexcitation is also dissociative. In the case of any 
 one of the drugs which produces dissociative conditions in 
 the nervous system, the condition may be overcome by the 
 ordinary processes of recuperation by which the organism 
 throws out the drug. In some cases the effort of the organ- 
 ism to restore the normal condition leads to a reaction which 
 is abnormally intense. We may then have for a time, as a 
 result of reaction to the drug, a state of hypersensitivity and 
 a more vigorous activity within the central nervous system 
 and in the muscles. The dissociating effects of such intense 
 activity in the nervous system may be, so far as consciousness 
 and muscular coordination are concerned, quite as abnormal 
 as the depressing effects of fatigue or complete suspension 
 of nervous activity. Thus, if the stimulations coming to the 
 central nervous system are much increased in their intensity 
 because the nervous tissue has been thrown into a condition 
 of heightened activity, there may be an irregularity in the 
 central nervous processes due to the abnormally strong cur- 
 rents of excitation and to the impossibility of restraining 
 these currents of stimulation within the ordinary channels 
 of connection and discharge. The disorganization here is 
 like the disorganized behavior of a stream that overflows 
 its banks. 
 
 Toxic effects of certain diseases. There are certain condi- 
 tions produced in nature which are quite analogous to those 
 which are produced by drugs. Such conditions appear in. 
 
DISSOCIATION 287 
 
 fevers when the organism is under the influence of certain 
 toxic substances produced by the organism itself or by 
 bacteria lodged in the body ; under such conditions the 
 nervous system is rendered hypersensitive through the 
 chemical action of these foreign substances on the tissues. 
 The delirium of the fever patient presents clearly the picture 
 of too intense activity in the central nervous system, and the 
 muscular activity of such an individual is directly related to 
 his irregular and excessive central processes. Such a person 
 may also be excessively sensitive to slight sounds or other 
 irritations of the organs of sense. 
 
 These negative cases as evidences of the relation between 
 normal consciousness and organization. These different 
 cases show the relation between nervous organization and 
 mental organization, and by their negative characteristics con- 
 firm the discussions of the preceding chapters, in which it 
 has been maintained that normal mental life is a continuous 
 process of integration and organization. 
 
 Hypnosis a form of dissociation closely allied to sleep. 
 The condition known as hypnosis has long been the source 
 of superstitious wonder, and much has been said and written 
 in regard to it which would tend to increase the mystery 
 which attaches to it. In many respects it is a condition 
 closely related to normal sleep. On the other hand, it has 
 certain peculiar characteristics which differentiate it from 
 ordinary sleep. These peculiarities can, however, be fully 
 understood under the formula adopted in explanation of 
 normal sleep, provided that formula is slightly modified to 
 include certain specialized forms of dissociation. 
 
 Hypnosis as partial dissociation. While normal sleep in- 
 volves the uncoupling or dissociation of the nervous ele- 
 ments, especially of the type which suspends activity in 
 the higher centers, hypnosis involves a dissociation which 
 is partial and leaves a part of the higher centers in action. 
 To put the matter in simple terms, we may say that in 
 
288 PSYCHOLOGY 
 
 normal sleep the cerebrum is dissociated from the lower 
 centers, and all the centers in the cerebrum are dissociated 
 from each other ; whereas, in hypnosis only a part of the 
 cerebrum is dissociated from the lower centers. The 
 remaining part of the cerebrum continues to carry on its 
 activities and, indeed, profits by the cessation of activity 
 in the dormant portion, for the active part of the nervous 
 system is, in such a case as this, supplied with an unusually 
 large amount of blood, and its activity may reach a much 
 higher level of intensity, because of this superior nutritive 
 supply and because of the concentration of all of the nerv- 
 ous activity in one region. Such a crude statement as this 
 is undoubtedly too simple in its terms, and yet it represents 
 the situation in principle. 
 
 Methods of inducing hypnosis. The way in which the con- 
 dition of partial or hypnotic dissociation is produced in the 
 nervous system differs with the practice of different hypno- 
 tizers. One of the characteristic methods of producing 
 hypnosis is to require the subject to gaze at some bright 
 object until a kind of partial stupor comes over him. He 
 may then be aroused to activity through the sense of hear- 
 ing. The ideas which he receives and the activities which 
 he performs have, under these conditions, many of the 
 characteristics of dissociation. Another way of producing 
 hypnosis is to soothe the subject into a sleeplike condition. 
 Stroking the forehead or the face is very commonly prac- 
 ticed by hypnotizers. Here again, the appeal to the subject, 
 after the dormant condition has set in, is through the sense 
 of hearing or even through the sense of vision. 
 
 Hypnosis more readily induced after it has once been estab- 
 lished in a subject. When a subject has been frequently 
 hypnotized, it is possible to reproduce the hypnotic condi- 
 tion without elaborate preliminaries. The subject acquires 
 what may be called a habit of dissociation. A simple order 
 from the hypnotizer is enough to throw the subject into the 
 
DISSOCIATION 289 
 
 condition. Sometimes the habit is carried to such an ex- 
 tent that the subject is able to throw himself into the hyp- 
 notic condition. Such self-induced hypnosis is known as 
 auto-hypnosis. The ability to produce the hypnotic state 
 in the subject does not depend upon any peculiar powers 
 on the part of the hypnotizer ; it depends rather upon his 
 ability so to influence his subject that the condition of par- 
 tial sleep described shall be induced. The essential condi- 
 tion with which the subject himself must comply, in order 
 to come under the influence of a hypnotizer, is that he con- 
 centrate his attention. The only persons who cannot be 
 hypnotized are young children, idiots, and insane persons, 
 all of whom are unable to concentrate attention. This state- 
 ment effectually disposes of the popular belief that only 
 weak-minded persons can be hypnotized. The most effec- 
 tive method of avoiding hypnosis is to scatter attention as 
 much as possible over a great variety of objects. Concen- 
 tration of attention is always favorable to hypnosis and 
 allied conditions. The audience which gives close attention 
 to a speaker or performer is susceptible to a species of 
 hypnosis ; while, on the other hand, there is no danger of 
 hypnosis in a distracted audience. The methods of induc- 
 ing hypnosis have been accidentally discovered from time 
 to time by performers who are then able to give striking 
 exhibitions of their discovery. Many oriental jugglers be- 
 gin their performance, the success of which undoubtedly 
 depends upon their hypnotic influence over their audiences, 
 with a dance in which the body of the performer is moved 
 with a gradually increasing speed, which inevitably induces 
 a gradually increased concentration of attention on the part 
 of the observer. When this dance grows more and more 
 rapid and more and more engaging to the attention, the 
 observer is completely mastered and the main performance 
 may be undertaken. The hypnotic influence of such a dance 
 is very frequently augmented by the burning of incense. 
 
290 PSYCHOLOGY 
 
 which has more or less of a narcotic effect upon the ob- 
 servers. In Hke manner, certain animals are probably 
 drawn into a hypnotic state by the movement of snakes. 
 This has frequently been reported in the case of birds and 
 monkeys. 
 
 Various characteristics of the hypnotized subject. When 
 the hypnotic state has been produced, the phenomena ex- 
 hibited are of two distinct types. First, there is a suspen- 
 sion of certain activities, and, second, there is an abnorm^al 
 heightening of other activities. This may be seen with 
 reference to the reception of sensory stimulations. Certain 
 stimulations are no longer received by the hypnotized sub- 
 ject. For this reason the condition has sometimes been 
 used by savage tribes for surgical purposes, exactly as in 
 modern life we use drugs which will produce a dissociation 
 of the nervous system and thus prevent pain from exces- 
 sive external stimulation. On the other hand, certain other 
 senses may be opened to stimulation. A hypnotized subject 
 may be wholly anaesthetic in his skin, while still retaining 
 the ability to receive impressions through certain of his 
 other senses. Indeed, the concentration of nervous activity 
 in certain particular senses results in such a heightening 
 of their ability to receive impressions that the subject may 
 perform most astonishing feats of sensory receptivity. He 
 may hear very faint sounds or he may see remote visual 
 objects. It is to be noted that this hypersesthesia of the 
 senses is not so extraordinaiy as it would at first sight seem 
 to be. We all become hyperaesthetic when we concentrate 
 attention in any direction. If one is listening for an im- 
 portant signal or watching for some object which is of 
 great importance to him, he will be using his nervous 
 energy in the emphasized direction and will be correspond- 
 ingly impervious to impressions from other sources. The 
 conditions in hypnosis are merely exaggerations of those 
 which appear in ordinary life. 
 
DISSOCIATION 291 
 
 Ideas not subjected to criticism in hypnosis. Turning 
 from the sensory processes to the central processes, we 
 find again that certain activities are entirely in abeyance, 
 while others are much intensified. If, for example, it is 
 suggested to a hypnotized subject that he is an animal 
 instead of a human being, the suggested idea may take such 
 large possession of him as to command his whole attention 
 and guide his activity. If a normal individual is told that 
 he is an animal, he immediately brings to bear upon the 
 suggested idea a great variety of incompatible experiences, 
 which make it clear that the statement is false and unaccept- 
 able. In the case of the hypnotized subject, very much as 
 in the case of the dreamer, the corrective ideas, which con- 
 stitute the fabric of normal life, are absent, so that the 
 single idea takes full possession of the mind and commands 
 belief as the accepted content of consciousness. This credu- 
 lousness of the hypnotic consciousness is described by say- 
 ing that the subject is very open to suggestion. Anything 
 that is said to him will be accepted, and any form of inter- 
 pretation of experience which is offered to him will be 
 taken up without serious question and without any effort 
 on his part to criticize the ideas which have been given him 
 by the hypnotizer. Suggestibility has very frequently been 
 emphasized to the exclusion of the converse fact that the 
 hypnotized subject is quite incapable of subjecting any ideas 
 to critical comparison. So also the positive increase in 
 sensitivity has been the impressive fact ; the diminution of 
 sensibility has often been overlooked. The negative con- 
 siderations are, however, essential to a complete under- 
 standing of the case, just as the negative considerations 
 are of importance if we would understand the credulousness 
 exhibited in dreams. 
 
 Dual personalities in hypnosis. The central nervous con- 
 ditions which are induced in hypnosis are sometimes suffi- 
 ciently unstable to produce the most complex phenomena. 
 
292 PSYCHOLOGY 
 
 It is sometimes found that the dissociated parts of the cere- 
 brum are not only dissociated from each other, but they 
 are also, to a certain extent, capable of independent action. 
 Thus, while one part of the cerebrum seems to be dealing 
 with impressions received through the sense of hearing, 
 another part may be engaged in responding to tactual im- 
 pressions. Or, the case may be rendered even more com- 
 plicated by the fact that the impressions coming from one 
 ear seem to serve as stimulations for certain activities, while 
 auditory impressions received on the opposite side of the 
 body are effective in producing an entirely different set of 
 experiences and responses. There result in such cases 
 what are known as dual and multiple personalities. By 
 personality, as the term is used in such cases, is meant 
 any organized group or system of ideas and activities. 
 The various groups of systematized activities and ideas 
 which exist side by side in a hypnotized subject owe 
 their separation to nervous and mental dissociation ; each 
 personality is, therefore, a relatively less complex system 
 than that which exists when the whole cerebrum is acting 
 as a single organ. The division of an individual into a. 
 number of systems of organization appears in other states 
 than the hypnotic state, and it may result in certain per- 
 manent or certain temporary disruptions of personality, 
 which have been noted in such stories as that of Dr. Jekyll 
 and Mr. Hyde. 
 
 Dual personalities in other than hypnotic conditions. 
 From time to time one reads of a case of lapse in memory 
 which afnounts to a dissociation of personality. A man for- 
 gets who he is or what business he has, been following. He 
 is sufficiently normal in his general organization to respond 
 to a great variety of impressions in a regular fashion, but 
 the complex structure of mental life breaks down and 
 the man is only partly reconstructed in the second self. 
 Tertiary and quaternary personalities may appear in all 
 
DISSOCIATION 293 
 
 possible combinations. The secondary or tertiary personality 
 may know its fellows, but may be itself quite forgotten. 
 Several cases have been described in which personality B 
 knows not only its own acts and emotions but also the acts 
 and emotions of the other personality A, Sometimes B not 
 only knows but heartily dislikes A. Sometimes two per- 
 sonalities exist simultaneously wdthin the same body and 
 seem to have separate lives and characters. The writer 
 knew of a case of a young man who was the object of 
 superstitious wonder in the village in which he lived, be- 
 cause he had two personalities. These two personalities 
 knew each other and held long discussions with each other. 
 Often, when they came to a turn in the road, they dis- 
 agreed with each other as to the direction in which their 
 body should move, and the passer-by could see the abnormal 
 man mumbling an argument between his two selves. 
 
 Dual and multiple personalities analogous to the various 
 selves of normal life. The details of such cases are baffling 
 iij the extremic, but nothing can be clearer from our earlier 
 studies than the general formula of dissociation, with the 
 added fact of partial organization around different centers. 
 The matter becomes more intelligible if we remember that 
 even in ordinary life there is a subdivision of experience 
 into different systems. We distinguish, even in common 
 parlance, between the business self, the social self, and so 
 on. Each one of these selves is only partially related to the 
 other systems of experience and forms of behavior. The 
 man w^ho is buried in the details of a business transaction 
 is just as oblivious to considerations of a literary sort as the 
 hypnotized subject is oblivious to a certain group of possible 
 experiences. We do not call the ordinary absorption of the 
 self in business a case of multiple personality, because 
 the neglected personality in the case of the business man 
 is not so remote but that it can be immediately called out, 
 if he turns, his attention to some literary considerations. 
 
294 PSYCHOLOGY 
 
 The normal individual is capable of transferring his atten- 
 tion and interest from center to center according as the 
 external environment demands, while the hypnotized subject 
 or abnormal person is, through dissociation, quite incapable 
 of a rapid transfer of attention or of correlating the different 
 phases of his experience. 
 
 Hypnosis a transient condition, insanity permanent. We 
 shall return to the discussion of multiple personality under 
 the general head of insanity, for the fundamental distinction 
 between insanity and hypnosis is to be found in the degree 
 of permanency which is attained in the former state, as 
 contrasted with the more transient character of the hypnotic 
 condition. 
 
 Movements sometimes normal in hypnosis , because the 
 lower centers are not dissociated. In the meantime, it is 
 necessary to add a few comments on the motor activities of 
 hypnotized subjects. These motor activities frequently ex- 
 hibit little or no departure from the ordinary coordinations 
 of normal life. The hypnotized subject is capable of walk- 
 ing, often of writing or producing certain other complex 
 forms of movement. Such continuation of the bodily coordi- 
 nations is explicable on the ground that the lower centers of 
 the nervous system are not dissociated by the changes that 
 take place in the higher centers. Whenever the higher 
 centers are able to send stimulations to the lower centers, 
 these lower centers are capable of responding with their 
 usual degree of coordination. The lack of organization is 
 exhibited rather in the inability to maintain a normal bal- 
 ance between the various centers which call the lower centers 
 into play. It is to be noted, however, that the movements 
 of hypnotized subjects sometimes indicate by their clumsi- 
 ness and lack of precision that the disintegrating force has 
 affected certain of the motor channels as well as the central 
 organizations. This is especially true when the attempted 
 act involves a complicated coordination. 
 
DISSOCIATION 295 
 
 The after-effects of hypnosis tend to become permanent. 
 
 There is one group of facts in hypnosis which should 
 perhaps be made the subject of special comments. The 
 suggestions received by the hypnotized subject may, in 
 some cases, be carried over so as to become operative in a 
 later period, after the subject has apparently recovered from 
 the hypnotic trance. Such after-effects are known as post- 
 hypnotic effects, and the suggestions are described as 
 post-hypnotic suggestions. Even more significant is the fact 
 that after-effects of the hypnotic trance are of a general 
 kind. It is a fact that the effect of the hypnotic state is in 
 the direction of a perpetuation of dissociative tendencies. 
 Sleep is transient and leads to a more vigorous form of 
 activity after it is over. Hypnosis, on the other hand, tends 
 not to restore the nervous system to a more vigorous condi- 
 tion but to perpetuate dissociation. This is due to the fact 
 that sleep is negative, while hypnosis is positive in certain 
 * of its phases, in that it trains certain centers to act without 
 reference to others. It therefore operates by virtue of its 
 positive phases toward permanent disorganization. It is for 
 such reasons as these that the use of hypnosis is in general 
 to be avoided. The disorganizing effects of hypnosis are of 
 the same general type as the disrupting tendencies of certain 
 drugs. The individual, who with sufficient frequency comes 
 under the influence of these drugs or of hypnosis, will 
 ultimately settle into a state of nervous disorganization from 
 which it will be quite impossible for him to recover, even 
 when recovery is demanded for the purposes of normal 
 life. Hypnosis is not utilized by reputable practitioners, 
 because its ultimate effects are not as readily controllable 
 as are the effects even of the narcotic drugs ; and there is 
 no justification whatever for the use of hypnosis as a means 
 of amusement, any more than there would be for using a 
 strong narcotic drug to bring an individual into a condition 
 which would make him a source of entertainment. 
 
296 PSYCHOLOGY 
 
 Insanity a permanent form of disorganization, intro- 
 duced in many cases by dissociation and settling into an 
 abnormal reorganization. As has been indicated in the 
 eariier paragraphs, insanity is a form of relatively permanent 
 dissociation. Certain forms of delirium, which have been 
 referred to before, furnish the best introduction to the study 
 of insanity. In delirium the subject is so highly excitable 
 that the normal avenues of stimulation and discharge are 
 for the time being completely disrupted, and the currents 
 of nervous activity and the corresponding facts of experience 
 are dissociated. As delirium disappears and gives place to 
 the usual intensity of nervous activity the individual may 
 return to the earlier normal condition or, on the other 
 hand, there may be left behind a permanent abnormal state, 
 because the earlier forms of organization are not fully 
 restored. One of the most characteristic symptoms of all 
 forms of insanity is found to be the existence of certain 
 hallucinations or fundamental abnormalities in the subject's 
 world of ideas. The insane person believes himself to be 
 Julius Caesar or some Biblical character, or even some 
 divinity. There is no difficulty in recognizing the fact that 
 the idea of transferred identity may come into the mind of 
 any normal individual. It is, however, in the case of a 
 normal individual immediately criticized and abandoned, 
 because of its incompatibility with the person's general 
 knowledge of the world and his place in it. When the 
 compact organization which has been built up in normal 
 experiences has once given way, and the idea that one is 
 Julius Caesar or some other character has presented itself 
 as a center of reconstruction in the midst of the resulting 
 chaos, there is a possibility of an abnormal reorganization 
 of experience. The individual is no longer restrained by 
 that system of ideas which has been laboriously built up 
 through contact with the world ; the result is that the whole 
 later ideational life of the individual loses its adaptation to 
 
DISSOCIATION 297 
 
 the real world. The characteristic fact in certain cases 
 of insanity is, accordingly, not describable in simple terms 
 of dissociation ; it is rather to be defined in terms of disso- 
 ciation with an abnormal association or integration following 
 upon the breaking down of the normal system. In other 
 cases, disintegration is the more obvious fact. The individual 
 simply loses control of his ideas, and his mind seems to be 
 flooded with an incoherent mass of experience. His words 
 reflect this incoherency of ideas, and his behavior indicates 
 an absence of self-control. Such disintegrated forms of 
 consciousness and behavior commonly appear in the last 
 stages of almost every kind of insanity, even where there 
 has been for a time reorganization about an abnormal center. 
 Melancholia as a typical form of dissociation. One of 
 the very general forms of dissociative abnormality is that 
 which appears in so-called melancholia. In melancholia 
 there is a general reduction of all the bodily activities, 
 including the activities in the nervous system. The subject 
 becomes phlegmatic and depressed in all his functions. 
 The whole feeling tone of experience takes on a marked 
 disagreeable character, which can be explained in terms of 
 our earlier discussion of feeling by saying that the individual 
 does not arouse himself easily to respond to any form of 
 stimulation, and when his nervous system is in any way 
 aroused by powerful external excitation, the reaction upon 
 the stimulus is so laborious and contrary to his tendencies 
 and mood that he has a strong feeling tone of a disagree- 
 able type. The ideas which such a subject has are often 
 organized about each other in a way that furnishes a kind 
 of false explanation of the subject's mood. The melancholic 
 subject has certain grievances against the world. Sometimes 
 these grievances are of a trivial character and make it clear 
 that the grievance could not have been the exciting cause of 
 the subject's condition. Sometimes the grievance is more 
 real and furnishes an apparent ground for the condition. 
 
298 PSYCHOLOGY 
 
 Even in such a case it is to be said that the person*s 
 physical condition must have developed into one of general 
 debility before the apparent cause of his mental conditions 
 could have become the source of abnormal melancholia. 
 The distinction between a passing case of depression in- 
 normal life and melancholia is that passing depression is 
 temporary, and nature rebounds from it in such a way as 
 to produce normal conditions after the depressing circum- 
 stances are past. In the case of melancholia the depressing 
 tendencies become permanent, and it is this permanency 
 rather than the fact of depression or its corresponding 
 nervous conditions which constitutes the characteristic fact 
 in insanity. Indeed, one can find almost every possible 
 grade of transition from normal life to extreme abnormality. 
 The result is that those who have made a special study of 
 these transitions, and those whose attention is for the first 
 time called to the possibility of such transition, are likely 
 to indulge in the extravagant statement that all persons are 
 at times or on certain subjects more or less insane. It is 
 undoubtedly true that all persons do depart at times from 
 the type of mental and bodily organization which constitutes 
 normal life, but unless these states become fixed and lead 
 to distorted and unadapted forms of behavior, they should 
 not be classified as cases of insanity. 
 
 Excessive excitation as a second typical case of insanity. 
 The opposite tendency to the melancholic condition just 
 described appears in certain cases of excessive excitation. 
 A person when abnormally excited is very frequently pos- 
 sessed of excessive bodily strength. This is not due to any 
 change in the structure of his muscles, but rather to the 
 fact that the nervous system which is in control of the mus- 
 cles is sending to the active organs stimulations of excessive 
 intensity. There are numerous cases in normal life which 
 will help us to understand this fact. If an individual is 
 fatigued, encouragement and stimulation from the outside 
 
DISSOCIATION 299 
 
 world will appreciably increase his ability to execute muscular 
 movements. In the same way an individual may be so 
 stimulated by abnormal substances in the blood that his 
 whole nervous behavior is raised to a high level of activity 
 and the motor discharges are abnormally intense. The 
 muscular activity of such a person is typical of his whole 
 condition. His ideas come in an overwhelming flood and 
 lead him into the most extravagant excesses of imagination 
 and lack of self-control. 
 
 Fundamental disturbances of instinctive and emotional 
 life. Of late much attention has been given to the fact that 
 in all cases of dissociation the fundamental instincts assert 
 themselves and play a leading part in the behavior and 
 ideation of the abnormal individual. For example, there 
 are types of fear which haunt a patient and distract him 
 from all normal modes of thought and life. Or the sex 
 instinct becomes dominant, or the food instinct leads to 
 irregular or irrational behavior. The mode of treatment 
 which is adopted in such cases aims in part to restore 
 normal nutritive conditions and then proceeds on the as- 
 sumption that the individual must be started on the road to 
 a reconstruction of his mental world. Often the shortest 
 route to this latter goal is to bring out in explicit detail some 
 of the deep-seated dissociations. Thus, the person who is 
 suffering from terror tis made aware of the sources of his 
 terror and is encouraged to reorganize his thinking and his 
 attitudes toward the object of his dissociation. The abnormal 
 state can be compared to physical clumsiness. The indi- 
 vidual whose muscles will not coordinate must develop 
 physical cooperation of the organs of his body by using 
 them in a well-ordered, systematic fashion. So with the 
 person suffering from mental incoordination, there must be 
 a well-directed effort at mental recoordination. 
 
 Relation of psychiatry to psychology. These illustrations 
 must suffice for our present purposes. There are all possible 
 
300 PSYCHOLOGY 
 
 combinations of disintegration and reorganization exhibited 
 in insanity. There is a science known as psychiatry which 
 deals with these forms of dissociation and abnormal associ- 
 ation, and there is a large field of practical observation and 
 study open here to the trained scientist. The chief lesson 
 for our general science is that the normal processes are 
 processes of integration leading to forms of association which 
 contribute to adaptation. There are frequently illustrations 
 which throw light upon important principles of normal asso- 
 ciation, to be found by making a careful study of the facts 
 of dissociation, but in general the explanation of abnormal 
 states is made easier by a careful examination of normal 
 processes rather than the reverse. It does not follow that 
 dissociation will be along the same lines as association, and 
 the effort to work out the details of one by the other often 
 leads to fallacies. The general tendency of normal life is, 
 however, obviously in the direction of adaptive organization ; 
 the tendency of sleep, hypnosis, and insanity, on the other 
 hand, is in the opposite direction. The particular path fol- 
 lowed in each case can be defined only through empirical 
 examination of the case. 
 
CHAPTER XV 
 
 VOLUNTARY ACTION AND VOLUNTARY ATTENTION 
 
 Voluntary action a special form of behavior. Though the 
 preceding chapters have discussed at length many of the 
 relations between bodily activity and mental processes, they 
 have not dealt specifically with that form of behavior which 
 is described by the term ''voluntary choice." One may 
 reach out and pick up the book before him, or one may 
 decide not to touch the book. One may take the pen and 
 sign a contract, or one may refuse to sign. The whole per- 
 sonality enters into such a decision, and we recognize both 
 in ordinary thought and in scientific consideration of the 
 matter that the ability to choose, especially the ability to 
 choose wisely and consistently, is the supreme power culti- 
 vated in the development of the individual. Our penal code 
 recognizes the fact that an immature child is not responsible 
 for his actions in the measure in which a full-grown man is 
 responsible. Those who are mentally defective are exempt 
 from the penalties of the law just in the degree in which 
 they fall short of normal development. These and other 
 illustrations of common practice show that voluntary choice 
 is the fullest expression of the developed normal self. 
 
 Instinctive behavior different from voluntary action. The 
 explanation of voluntary action depends on a series of dis- 
 tinctions which have been implied in earlier chapters. Thus 
 instinctive acts are not forms of voluntary behavior. For 
 example, the infant swallows not from deliberate choice but 
 because nature has provided a nervous and muscular mecha- 
 nism which responds promptly to the proper sensory stimulus. 
 
 301 
 
302 PSYCHOLOGY 
 
 One has only to think of the cases in adult experience where 
 the swallowing reflex acts when the swallower vv^ould gladly 
 check it. Furthermore, most people do not know that they 
 cannot carry out the act of swallowing without a proper sen- 
 sory stimulus. Let one try the experiment of swallowing 
 five times in succession. All the saliva in the mouth will 
 have been swallowed the second or third time the effort is 
 made, and after that the mechanism refuses to work until 
 more sensory stimulation is supplied. Instinctive acts are 
 therefore different from volitions. Sometimes we can volun- 
 tarily check one of these acts, although here our powers are 
 limited, and we can in some measure decide when an act 
 provided by the inherited nervous mechanism shall be 
 allowed to take place, but here again our control is limited 
 as shown in the example given above. 
 
 Impulsive acts distinct from higher forms of voluntary 
 action. If we follow the development of an individual from 
 infancy, we find that there are other forms of behavior which 
 resemble the instincts in that they are not fully under con- 
 trol. For this general class of acts we commonly use the 
 term ''impulsive acts/' It is almost impossible not to imi- 
 tate a yawn ; it is very difficult not to look around when one 
 hears an unfamiliar noise. The impulse to take food when 
 one is hungry is very strong ; the impulse to strike back 
 when one is struck is so strong that the interpretation of re- 
 sponsibility is always based on an examination of provocation. 
 
 Impulsive acts as phases of general muscular tension. 
 Impulsive acts can be explained by formulas which have 
 been discussed at length in earlier chapters. It was there 
 pointed out that the whole organism is constantly at a higher 
 .or lower level of tension. The muscles of a waking person 
 are always on the stretch. There are internal activities of 
 respiration and circulation and digestion which are not only 
 in a state of tension but are in an actual state of continuous 
 operation. The eyes are usually focused on some object ; 
 
VOLUNTARY ACTION AND ATTENTION 303 
 
 the hand is seldom at rest and still more seldom in a state 
 of relaxation. This state of muscular tension and internal 
 action is due to the continuous stream of nervous impulses 
 which flow out to the active organs. The outgoing motor 
 impulses are in turn the results of the sensory stimulations 
 of the moment and the reverberations of sensory impressions 
 which are circulating through the massive cerebrum. 
 
 Impulsive acts explicable through nervous organization. 
 An impulsive act exhibits in its particular form the past 
 experience and training of the individual. We often judge 
 of a person's character and education by his impulsive acts. 
 The spy who was betrayed by his impulsive and wholly 
 uncontrolled response to a sudden military order to stand 
 to attention exhibited his training by his very lack of vol- 
 untary control. One may guide his impulses in some 
 measure by the slow process of changing his habits. If 
 one tends to look up from his work every time a shadow 
 passes over his desk, one may overcome this tendency by self- 
 discipline ; but in that case the inadvertent lapses into the 
 old mode of looking up will furnish the strongest evidence 
 of the difference between impulse and voluntary control. 
 
 Impulse comparable to involuntary attention. The term 
 ''impulse" as applied to behavior finds a parallel in certain 
 terms which are used in describing strictly mental processes. 
 .One tends to look at any object that moves through the 
 edge of the field of vision. This is an impulsive tendency. 
 On the psychical side we describe this fact by saying that 
 moving objects in the edge of the field of vision attract 
 involuntary attention. Attention of the involuntary type is 
 then contrasted with certain higher types of attention 
 which are designated as voluntary. Thus, when one keeps 
 his eyes fixed steadily on the signal which he is set to 
 watch in spite of distracting appeals to his involuntary 
 attention, we speak of his effort as an exhibition of volun- 
 tary choice or self-control. 
 
304 PSYCHOLOGY 
 
 Impulse and involuntary attention related to perception 
 and habit. It is hardly necessary to elaborate here the 
 matter of the relation of impulsive activity to perception 
 and habit. Our earlier chapters have abundantly illustrated 
 this relation and shown its importance. We have, however, 
 reached the point where we must face the problem of the 
 distinction between voluntary attention and all lower forms of 
 perception and thought, and the problem of the distinction 
 between voluntary action and impulse. 
 
 Simple case of choice. Perhaps the best method of 
 making progress toward the solution of our problem is to 
 analyze one of the simpler cases of volition. For this pur- 
 pose let us consider choice in the presence of two clearly 
 apprehended alternatives. There lies before the man who 
 is out on a walk a fork in the road. Sometimes he will 
 thoughtlessly strike out on that path which he has often 
 followed, or because he is absorbed in thought he will be 
 guided by mere accident. But in the case in which we are 
 interested he sees the two roads clearly ; each is inviting, 
 and in terms of his experience and training, equally acces- 
 sible ; he may even pause a moment and then he turns to 
 the left or right. We can explain this turning in a broad, 
 loose way by using such phrases as ''he decided," ''he 
 chose," "he selected." The impressive fact about each 
 of these phrases is that it brings out the truth that we are 
 in the presence of an explanation which includes and in- 
 volves personality. We may speak of impulse in an imper- 
 sonal way. One is led to do something when he acts under 
 the spell of impulse, but one makes the decision himself 
 when he chooses his road. 
 
 Behavior of the higher types dependent on ideas. The 
 broad terms of our explanation do not satisfy the demand 
 for a scientific account of the process of choice. We 
 must go into greater detail. We can do this in some 
 measure by pointing out that bodily activity is related to 
 
VOLUNTARY ACTION AND ATTENTION 305 
 
 ideas no less than it is to percepts. One thinks of a tall 
 object and, as we have seen in an earlier chapter, he tends 
 to move his eye and his hand upward. One thinks over 
 an offense which has been committed against him and he 
 grows red with rage and tense for an attack. Ideas are 
 related to actions because the nervous processes involved 
 in the formation of ideas are, like all nervous processes, 
 parts of a succession of processes leading to a motor dis- 
 charge. In the association areas of the cerebrum there 
 are complex nervous combinations and deposits of earlier 
 excitations which are the immediate conditions of ideation 
 and at the same time links in the chain of processes 
 connecting the sense organs with the motor centers. 
 
 When as a result of experience an individual becomes 
 mature enough so that his sensory impulses are taken up 
 into a highly developed train of cerebral processes before 
 they are allowed to go to the motor centers, we say of the 
 individual that he acts on the basis of ideas. We mean by 
 this statement that the instinctive tracts are relatively less 
 and less important in this individual's life. We mean that 
 the inner organization is more and more important. The 
 inner organization of the cerebrum is, as we have seen, 
 relatively remote from mere sensation. Hence, when the 
 inner processes come more into control we find the expla- 
 nation of individual conduct not in present impressions 
 but in past experience. The first and most evident con- 
 clusion about voluntary choice is therefore that it depends 
 on a high development of central paths and is related to 
 the higher conscious processes. 
 
 Voluntary action and its complex background as contrasted 
 with lower forms of behavior. The significance of the fore- 
 going conclusion will be fully grasped only when it is re- 
 called that the central or ideational conscious processes are 
 complex as contrasted with mere perceptions and other 
 conscious processes which involve only the lower elements 
 
3o6 PSYCHOLOGY 
 
 of the nervous system and the lower phases of experience. 
 An idea is a composite of experience. The general fact 
 about ideational consciousness is that it brings into a single 
 instant of experience a vast variety of elements. Conduct 
 which is based on ideation is, accordingly, conduct which 
 springs, not out of some simple single impression, but out 
 of a combination of manifold impressions. 
 
 We have commented in earlier chapters on the advantage 
 which comes to the individual from the possession of a 
 world of ideas in which the whole of experience can be 
 compactly represented and readily rearranged. We see now 
 the advantage to conduct of ideational powers. The indi- 
 vidual who has ideas can act on a broader basis than can 
 the victim of mere impulse, or the undeveloped individual 
 who has only the most immediate sensory motives for his 
 comings and goings. 
 
 Decision a process of balancing ideas. Let us consider 
 once more our individual who must choose at the fork of the 
 road v/hich branch he will follow. No outsider can fathom 
 his choice. The inner world is the scene of a balancing 
 and comparing, and out of this inner world comes a decision 
 which turns the scale of muscular tension and results in a 
 movement. If at the moment before decision an outsider 
 would influence choice, he must appeal to the inner world ; 
 he must reach the thought process of the individual who 
 is deciding. 
 
 Decision largely influenced by organization built out of past 
 experiences. When we trace decision back into the inner 
 world, we find justification for a second general conclusion. 
 Volition is determined in very large measure by past experi- 
 ences. All ideas, as we know, are explicable only in terms of 
 organizations of experience which have been set up in the past. 
 The choice which an individual makes to-day has its roots in 
 the experiences of yesterday and of the earlier education be- 
 fore yesterday. To be sure, the present may bring into the 
 
VOLUNTARY ACTION AND ATTENTION 307 
 
 mind a manifold of experiences out of which choice must 
 issue, but this manifold will be arranged and organized in 
 terms which comport with the past as well as with the present. 
 We know in ordinary life that it is safe to assume that an 
 individual who has made his decisions thus and so in the past 
 will in the future exhibit like tendencies of choice. 
 
 The relation of choice to past experience is impressively 
 illustrated by the fact that voluntary attention is controlled 
 by what one has learned to think about. If one puts oneself 
 through a series of experiences in which aesthetical objects 
 are again and again examined and recorded in thought, it is 
 safe to predict that aesthetic objects will in the future be centers 
 of long concentrated attention. If one gives heed for years 
 to matters of business to the exclusion of all other objects of 
 thought, it is sure to be a great deal easier to fix attention on 
 matters of this type in all future experience. 
 
 We come back to the formula with which our explanation 
 began. Whatever enters into the personality of a man enters 
 into his voluntary choice. When a man chooses, he expresses 
 his personality. This is the essential fact about volition ; choice 
 is not an arbitrary, sudden mode of thought or action ; it is, 
 rather, the consummate expression of all that has entered 
 into individual life. 
 
 The meaning of prevision. While emphasizing the impor- 
 tance of past experience in the development of voluntary con- 
 trol it is important that we should understand also the fact 
 that volition looks by m.eans of imagination into the future. 
 One recombines ideas and foresees in this world of ideas 
 certain consequences of this or that combination. Behavior 
 is then dominated, not by present impressions or by habits 
 alone, it is guided by the products of imagination. The thinker 
 has tried out consequences in the world of thought and has 
 the advantage in conduct of these purely mental trials. The 
 power of imagination thus comes to be more important for 
 human conduct than even habit or instinct. 
 
308 PSYCHOLOGY 
 
 For example, the general plans his movements with a map 
 before him and with a thousand items of information in mind 
 about the enemy and his own forces. His final orders are the 
 results of his comparisons and mental experiments. 
 
 The power of choice becomes thus a matter of the relation 
 of complex ideational processes to behavior. Conduct is re- 
 lated to ideas, and any elaborate process of combining ideas 
 which results in a new idea will influence behavior. 
 
 The problem of the freedom of the will. We are now in 
 a position to consider one of the problems which has long 
 been a subject of hot debate among students of human life 
 and conduct ; namely, the problem of the freedom of the will. 
 It has been argued on the one side that in a given emergency 
 an individual can follow any one of the various courses which 
 lie before him. The five or six paths which he might follow 
 all attract him, but he is free to follow the one which he 
 chooses. So far we must agree. But the extremists seem to 
 argue at times that the chooser is in no wise bound even by 
 his own earlier experiences and training. The individual is 
 free in the absolute sense, we are sometimes told. He may 
 at this given moment strike out without reference to his past 
 or to any other cause. His action is without determining 
 cause. He is a wholly independent being, unguided by any 
 outer or inner considerations except as he is willing in his 
 sovereign independence to give heed to these considerations. 
 This last statement of the doctrine has sometimes been called 
 the doctrine of libertarianism. For this view there is no evi- 
 dence. Personality is never free from its own past, even when 
 it is producing new combinations of ideas through imagination. 
 Personality is a product of organization. Personality is the 
 name of that individual nature which has been developed out 
 of the play and interplay of impressions and instincts and 
 conscious comparisons and imaginations. Personality is never 
 free from itself. Voluntary choice is an expression of per- 
 sonality, not of sheer caprice. 
 
VOLUNTARY ACTION AND ATTENTION 309 
 
 Voluntary choice guided by purposes. The conclusion 
 to which we are thus led gives the largest emphasis to those 
 reorganizations of experience which were discussed in the 
 chapter on concepts. We saw in that chapter how a dominant 
 inner purpose may control the organization of all thought. 
 I may resolve to think about a geometrical proposition, and 
 all my ideational processes will be rearranged and worked out 
 in conformity with this central purpose. The rise in the mind 
 of a dominant idea is therefore an important event, not merely 
 in a vague, abstract sense, but in a practical sense as well. 
 When some personality takes up with fixed purpose a definite 
 line of thought, his own conduct and ultimately that of his 
 social environment will be affected. This is what was meant 
 by the statement that consciousness is a cause and a very 
 potent cause in the world of affairs. 
 
 Behavior of a higher type is related to education. A text- 
 book on the science of human mental processes is not the 
 place for a homily on -conduct, but it is so obvious an in- 
 ference from what has been said that one can hardly refrain 
 from recording the principle that all choice and all signifi- 
 cant human influence in the world are dependent for their 
 character on the growth of ideas. He who would influence 
 his ow^n conduct or that of others must therefore look to 
 the roots of conduct in organized processes of ideation and 
 thought. 
 
 It wall be proper, therefore, for us to follow the study of 
 voluntary behavior by a discussion of some of the more 
 obvious devices by which human choices may be turned in 
 the direction of fruitful and efficient developments. 
 
 Early scientific studies of behavior purely external. Before 
 we apply the lessons we have learned, we owe it to the his- 
 tory of scientific method to comment briefly on the develop- 
 ment of scientific studies of human behavior. The earliest 
 scientific investigations of bodily activities were undertaken 
 from a wholly external point of view. The specific method 
 
310 PSYCHOLOGY 
 
 which was used for such investigations was devised by the 
 astronomers who were interested in understanding the defi- 
 ciencies of human movements when attempts were made to 
 use these movements in recording the transit of stars through 
 the field of the telescope. The astronomers found that the 
 hand cannot be moved as soon as the eye sees a light. 
 They therefore measured the interval which elapsed between 
 visual impression and hand movement. They found further 
 that different individuals have different personal equations, 
 or periods of reaction. Evidently the observations of the as- 
 tronomers are very suggestive as foundations for psychological 
 investigations. The early psychological investigators, how- 
 ever, did not transform the method into a psychological 
 method ; they took it over unmodified. Their investigations 
 of the active processes were not based upon any elaborate 
 analysis. Certain simple movements were measured with 
 reference to the time which elapsed between the stimulus 
 and the muscular contraction, exactly as this time had been 
 measured by the astronomers. The investigation of this time 
 of reaction was treated as an indirect means of getting at the 
 complexity of the nervous and conscious processes preceding 
 the reaction. It was found, for example, that the length of 
 time required for a simple reaction was appreciably shorter 
 than the length of time required for a reaction which involved 
 the discrimination of two simple colors from each other. Thus, 
 if the reactor were required to move his finger as soon as 
 possible after being stimulated by a flash of light, the meas- 
 urement of this interval gave what was called a simple reac- 
 tion time of about yq^-^q of a second, or 1 80 cr, the letter a 
 being used as the symbol for a thousandth of a second. If, 
 on the other hand, the experiment was arranged in such a 
 way that a number of different colors could be presented to 
 the subject, and it was prescribed that he should react only 
 after a clear recognition of one of these colors, then the clear 
 recognition or discrimination added appreciably to the time 
 
VOLUNTARY ACTION AND ATTENTION 311 
 
 which elapsed between the giving of the stimulus and the 
 movement, sometimes as much as 60 cr. This longer period 
 of time was known as discrimination time. Again, if instead 
 of reacting always with the same hand or finger the reactor 
 was instructed to respond to one kind of stimulation with one 
 •movement and to another kind of stimulation with a second 
 movement, the process involved not merely discrimination 
 but also a simple choice of the organ to be moved. The 
 reaction time in this case was called choice time. 
 
 Purely external investigations not productive. The earlier 
 experimenters on reaction were satisfied to seek exact defi- 
 nitions of the lengths of these various kinds of reaction 
 time. They paid little or no attention to introspection on 
 the part of the reactor. The results of a large number of 
 reactions were averaged, and the comparison between differ- 
 ent simple mental processes was made in terms of these 
 general averages. The outcome for psychology of these ex- 
 ternal studies was by no means large. There is very little 
 contribution to the knowledge of human nature in the details 
 of reaction times. 
 
 Recent investigations and their stress on introspection and 
 analysis of movement. Recent investigations of reactions 
 differ from the earlier external measurements in two re- 
 spects. First, the effort has been made to find out, as far 
 as possible, what are the conditions in the experience of 
 the reactor during the reaction process. Attention has been 
 called, for example, to the fact that if the reactor's atten- 
 tion is turned toward his hand, rather than toward the organ 
 of sense which is to be stimulated, the time of reaction will 
 for most individuals be shorter. A distinction may therefore 
 be drawn between so-called muscular reactions and sensory 
 reactions. The average difference in time corresponding to 
 this introspective difference is often as great as 1000-. Again, 
 the different types of discrimination and choice have been 
 introspectively examined. The question of whether the 
 
312 PSYCHOLOGY 
 
 content of consciousness before a choice reaction is an image 
 of the movement to be executed, or a concentration of atten- 
 tion upon the sensation received, has been introspectively 
 studied. The results of these introspective studies have done 
 m.uch to clear up the psychological doctrine of volition. Fur- 
 thermore, the general outcome of a more careful examina- 
 tion of conscious correlates of reaction has shown how utterly 
 formal was the gross averaging of all kinds of cases in the 
 earlier investigations. It may be said that no introspective 
 differences ever occur without some modification in the dura- 
 tion of the reaction process ; hence, differences in duration 
 are highly significant when supported by introspective ob- 
 servation and should not be eliminated by an arbitrary 
 method of mathematical averaging. 
 
 Analysis of the form of movement. The second way in 
 which recent reaction experiments have been elaborated is 
 by analyzing the forms of the reaction movement. It was 
 formerly assumed that the act of lifting the hand from a 
 reaction key was so simple a process that it could be re- 
 garded as uniform in character throughout a long series of 
 experiments. Recent investigations show that there is no 
 such thing as an absolutely uniform series of movement proc- 
 esses. There are certain reactors, for example, who, when 
 they make an effort to lift the hand as rapidly as possible, 
 frequently go through a preliminary downward movement 
 before beginning the upward movement. There are other 
 preliminary phases of movement which prepare the way for 
 the final reaction, and the relation between these preliminary 
 movements and the final movement of the hand may be so 
 complicated as to influence measurably the duration of the 
 reaction period. The relation of these, complexities of move- 
 ment to nervous organization is most intimate. The studies 
 in earlier chapters of the relation of perception and feeling 
 to reaction have indicated the significance for psychology 
 of the analysis of reactions. By way of criticism of the 
 
VOLUNTARY ACTION AND ATTENTION 313 
 
 earlier studies, it may be said that they treated reactions as if 
 they were merely uniform mechanical processes. The recent 
 investigations have made it clear that the study of muscular 
 behavior is productive only when it is related to a complete 
 account of the introspective processes and the antecedent or- 
 ganizations which condition the particular form of movement. 
 Concept of organization as fundamental in all psychologi- 
 cal studies. The study of movement has therefore brought 
 us back to the consideration of principles of organization. 
 Volition' and impulse are merely the active correlates of or- 
 ganized forms of ideational and perceptual experience. The 
 earlier studies of mental activity and the present study of 
 behavior are mutually supplementary. We do not require 
 any unique formulas or the recognition of any new factors. 
 Behavior is a necessary and ever-present physical correlate 
 of experience and, at the same time, a product of all those 
 organizations which lie back of experience itself. 
 
CHAPTER XVI 
 
 MENTAL HYGIENE 
 
 Hygiene a suggestive teriu for psychology. Just as there 
 is a way of keeping one's physical organs in good condition 
 through the adoption of rational principles of nutrition and 
 exercise and sleep, so there is a way of organizing one's 
 mental processes with a view to meeting most efficiently the 
 demands of life. 
 
 Relation of psychological hygiene to physiological. The 
 first maxim of mental hygiene is that the nervous system 
 must be kept in a healthy condition. Indeed, physical hy- 
 giene here becomes an essential part of the application of 
 psychology. If the nutrition of the body is defective, the 
 nervous system suffers with the other organs, and the mental 
 processes become abnormal. The same is true of sleep and 
 the excretory processes. The body must be in good condition 
 if the mind is to do its work. 
 
 Coordination of bodily activities. Assuming for the pur- 
 poses of our discussion that the general physiological condi- 
 tion is favorable, the next maxim of mental hygiene is that 
 all one's activities must be brought into harmonious coopera- 
 tion, for the first function of the central nervous system is 
 to control and coordinate the parts of the body. Thus, when 
 muscles are contracting vigorously, there is a call for blood 
 in the particular part of the body which is in action. The 
 nervous system must distribute the blood supply of the body 
 in such a way as to meet the strenuous local demand and at 
 the same time keep all of the supporting organs properly 
 supplied. The young child has to acquire the ability to do 
 
 314 
 
MENTAL HYGIENE 315 
 
 this. At first his organic activities are subject to all kinds 
 of distractions and incoordinations. He is unprepared for any 
 sustained effort because his body is not yet a well-coordinated 
 system. 
 
 Perhaps the most striking illustration of the incoordina- 
 tion of a child's body is seen in the fact that excitement of 
 any kind interferes with digestion. Digestion is in very 
 large measure an active process. The glands are active in 
 secretion, and the muscles of the digestive organs contract 
 in rhythmical movements that are necessary in carrying the 
 food through the alimentary tract. The elaborate system of 
 organs thus involved in digestion must cooperate or the whole 
 process will be disturbed. Suppose that all is going well, 
 when suddenly a shock of violent stimulation comes to the 
 nervous system. The flood of uncontrolled excitement will 
 be discharged by the motor fibers into the inner muscular 
 system, and digestion and circulation and respiration will 
 be violently disturbed. It is one of the important • results 
 of training that disturbances of this type are overcome in 
 increasing measure. The mature nervous system tends to 
 check and distribute excitements so that the organism may 
 not be disturbed in its fundamental activities. 
 
 Little children are very often disturbed by mere social 
 excitements to an extent which seriously interferes with 
 life. An adult, on the other hand, can receive the same 
 kind and amount of stimulation and not be distracted from 
 the inner activities of organic life. The training of one- 
 self to receive all sorts of external stimulations without dis- 
 locating the inner machinery is one of the important lines 
 of personal training. 
 
 Control of excessive stimulations. The formulas which 
 can be adopted for such training are apparently contradic- 
 tory. First, one should have regular habits of life. This 
 will set up wholesome and balanced forms of action. 
 Second, one should expose himself from time to time to 
 
3i6 PSYCHOLOGY 
 
 irregular and exciting situations. Or, perhaps better put, one 
 is sure, if he Uves in the world with its various kinds of 
 experience, to be drawn out of mere routine by forms of 
 excitement which tend to break up his simple habits of life. 
 Then one should aim to overcome the disturbance of inner 
 life by deliberately controlling the excitement in order to 
 give the organic habits an opportunity to reassert them- 
 selves. Control often means relaxation. Let an excited 
 person take two or three long breaths ; let him relax the 
 jaw muscles or the muscles of the hands. Excitement which 
 tightens up the muscles can often be overcome by these 
 sheer physical devices. If the physical devices do not 
 suffice, let there be an appeal to voluntary effort. If the 
 excitement is one of fear, let the excited person face the 
 problem and explore the source of the fear. Let one reason 
 himself, if he can, into a less tense attitude. The fact is 
 that every experienced adult has in the course of his life 
 come to the point where he can deal more or less success- 
 fully with excitement. Ability to master excitement shows 
 an internal state of coordination of a high type. The organ- 
 ism has acquired ability to undertake several kinds of action 
 at once without interfering with its own life. 
 
 While emphasizing the importance of internal harmony, 
 it may be well to refer once more to the disintegrating 
 effects which follow chronic incoordination. All the disso- 
 ciations which were discussed in an earlier chapter have in 
 them elements of internal discord. The individual whose 
 nervous system is sending out conflicting and discordant 
 impulses is an unhappy individual in his conscious experi- 
 ence and an incoordinated individual in his active life. 
 
 Perceptual analysis. A third maxim of mental hygiene is 
 one which relates to perception. All progress in perception 
 and in muscular coordination results from particularization 
 or concentration of attention on definite items of experience. 
 It is worth the effort for everyone to learn to analyze the 
 
MENTAL HYGIENE 317 
 
 objects in his environment. Even if one is not going to use 
 the details of information at the moment, it is valuable from 
 the point of view of future adaptation to be able to concen- 
 trate attention and action on particular aspects of a situa- 
 tion. Most games illustrate this kind of demand. If a boy 
 learns to catch a ball, he trains himself in concentration of 
 attention and control of his muscles. In the animal world 
 nature provides young animals with a play impulse through 
 which the untrained individual is led into exploratory forms 
 of behavior which in later life will be of use in nosing out 
 real enemies and real prey. 
 
 As a practical measure of self-training, it may be urged 
 that everyone ought always to analyze what he encounters. 
 He should notice the details of behavior of those whom he 
 meets ; he should note the contour of the objects he sees. 
 If he gets a hint that there are details which he has over- 
 looked, let him train himself to go back and find these 
 details. The value of such self-control is not merely in the 
 results gained at the moment, but in the conscious tendency 
 to analyze. It was pointed out in an earlier chapter that 
 perception is an active process initiated by the individual. 
 The application of that lesson is that the individual must 
 be active if he would perceive completely. 
 
 Perceptual synthesis. The counterpart of the foregoing 
 demand for analysis is the demand that one cultivate the 
 power of grasping many impressions at the same time. The 
 observer should train himself to recognize at a glance as 
 much as possible. It is said that the schools which train 
 performers to give exhibitions of ability to recall a whole 
 box full of trinkets after a single glance begin in childhood 
 by exposing to the prospective performer for recognition, 
 after a very brief exposure, three objects, then four, then 
 five, and so on. The scope of attention is thus broadened. 
 
 All forms of expert observation involve this breadth of 
 apprehension. The expertness cultivated in reading involves 
 
3i8 PSYCHOLOGY 
 
 the power of recognizing at a glance a series of words. The 
 child is limited in his ability to grasp words and only gradu- 
 ally reaches the stage where he can take in many at once. 
 The poor reader is found to be one who has made little 
 progress in the cultivation of a broad range of attention. 
 Many an adult is seriously handicapped because he can 
 recognize at a glance only one word. The individual who 
 finds himself thus limited should train himself by going 
 rapidly over familiar material. The familiarity will give the 
 necessary clearness to details, for familiarity is likely to im- 
 ply some earlier analysis. The rapid view of the familiar 
 material will help to synthesize many elements into a single 
 experience. The limits to which skill may be cultivated in 
 this matter are described by saying that an expert reader 
 can very often surpass by two or three hundred per cent 
 an ordinary reader. 
 
 What is true of reading is true of other situations in 
 which expertness can be cultivated. The person who draws 
 learns not only to see minutely but to take in the totality 
 of a situation. The architect sees many features of a build- 
 ing and shows a grasp of both detail and general appear- 
 ance which the untrained individual can hardly compre- 
 hend. The skilled artisan sees more in every piece of 
 work of the type which he knows than can an inexpert 
 observer. 
 
 Dangers of specialization. There appears at this point 
 one of the crucial difficulties in education. Perception is a 
 process in which individual development is often highly 
 specialized. For example, the skilled artisan may see much 
 in the kind of materials with which he is used to dealing 
 and be quite oblivious to other perceptual facts ; the shoe- 
 maker sees the shoes which a passerby wears, but has no 
 interest in his tailoring. The fact is that perception is closely 
 related, as was shown in an earlier chapter, to special train- ' 
 ing in direct manipulation. The extension of experience to 
 
MENTAL HYGIENE 319 
 
 include many different kinds of percepts will therefore re- 
 quire deliberate effort on the part of the observer ; other- 
 wise he will fall into narrow modes of seeing only a small 
 part of the world. 
 
 Control of perceptual attitudes. Not only so, but the 
 limited range of ordinary perceptual experience is exhibited 
 in the fact that our attitudes toward the objects about us 
 are very often quite irrational. One dislikes a person whom 
 one meets, for no better reason than that the stranger re- 
 sembles an acquaintance whom the observer does not like. 
 The child likes a color because he saw it first in an agree- 
 able setting. If experience takes its course without super- 
 vision, these attitudes become fixed and the narrowness of 
 perceptual interpretation passes into a lifelong habit. 
 
 Practical study of one's own attitudes ought to raise one 
 above the level of accidental attitudes. It often requires 
 time and effort to set aside one of the ready-made reactions 
 which so easily attach to percepts. The person who is afraid 
 of thunder and lightning may have to drill himself for years 
 to overcome this attitude which has become second nature, 
 but a new attitude can be cultivated by anyone who will set 
 himself to the task. 
 
 Control of attitudes as a case of volition. In general, the 
 types of training which have been advocated in the last two 
 paragraphs are types which can be accomplished only through 
 the domination of experience by higher mental processes. 
 A man must know something of himself in an ideational way 
 if he is deliberately to cultivate new ranges of perception and 
 new attitudes. What he accomplishes through self-control 
 will ultimately reach back into his perceptual life and will 
 make him alert about many new opportunities to see and 
 hear; it will also make his personal attitudes more rational. 
 The result will be a richer perceptual life and a more whole- 
 some series of attitudes. Perception will thus grow and 
 overcome the inherent tendency toward specialization. 
 
320 PSYCHOLOGY 
 
 Rules of wholesome ideation. When one comes to 
 memory and ideation, to language and abstraction, the field 
 of applications in personal life is unbounded. A fev/ par- 
 ticular maxims of mental hygiene in these fields may be 
 selected, but the student will have to supply for his own case 
 most of the rules which will insure success of his mental 
 processes. 
 
 Economy of mental effort. One of the special problems 
 of memory is the problem of economy of effort. If one has 
 a passage of prose to learn by heart, how should he do it — 
 by learning a line at a time or by taking in large units ? 
 The answer supplied by careful experimentation is that he 
 should learn by large units. The reason why learning by 
 large units is advantageous is not far to seek. If one reads 
 to the end of a line and then goes back to the beginning of 
 the line, he sets up an association between the two ends of 
 the same line, whereas he ought to set up an association 
 between the end of the first line and the beginning of 
 the next. 
 
 The maxim that one should learn by large units can be 
 amplified to include many cognate cases. The student trans- 
 lating a foreign word looks up the word in the vocabulary 
 and glances through a long list of meanings, most of which 
 he rejects. It would be economy of mental effort in the 
 long run if he would master all the meanings, rejecting none 
 but including all in a complete view of the word. The failure 
 of the student to see this is due to the apparent ease of 
 accomplishing the limited immediate purpose, whereas he 
 ought to cultivate a broad, though more remote, purpose. 
 
 Preparation as aid to memory. Another general principle 
 of memory is that even a very abstract scheme which pre- 
 pares the mind in advance to retain experiences will make 
 it possible to hold more in memory than can be taken in 
 if the material is not arranged. This is illustrated by the 
 man who prepared himself to remember long arbitrary lists 
 
MENTAL HYGIENE 321 
 
 of words by setting up in his mind a series of a hundred 
 rooms, arranged in fixed order, in each of which was hung 
 a single mental picture ; then when the words to be re- 
 membered were given, he associated one with each succes- 
 sive mental room and picture. Later, by going through the 
 rooms in order, he could recall the series of associated 
 ideas. The prearranged mental scheme was the key to his 
 power to retain. 
 
 Still better is a rational scheme. The student of science 
 gets ultimately an outline of his subject in mind, and every 
 new author whom he reads falls into this scheme and is 
 classified in detail. A trained student thus cultivates a 
 method of remembering a great body of opinion by classi- 
 fying it. 
 
 If one wants to learn to remember what cards have been 
 played in a card game, let him have a plan of arranging 
 his own hand, and then the accidents of the game will be 
 forced into an orderly scheme. 
 
 Organization the key to all correct thought. The general 
 formula which emerges from all these examples is the 
 formula of organization. Ideas should be arranged. When 
 ideas are arranged, they can be carried in greater bulk 
 than when they are isolated. Indeed, they can never be 
 isolated in any absolute sense because some kind of asso- 
 ciation will always couple them together. Arrangement 
 means, therefore, an association which is dominated by 
 some clear purpose or plan. 
 
 The domination of thought by some leading idea. This, 
 general formula can be employed also in treating briefly 
 some of the phases of abstraction. The world is for each 
 individual rearranged in terms of personal interests and 
 personal modes of abstraction. The man whose ambition 
 is wealth selects out of everything that comes into his 
 experience those elements which have to do with money. 
 He comes ultimately to see the world from the one point 
 
322 PSYCHOLOGY 
 
 of view. The man whose ambition is power sees men and 
 things from an entirely different point of view. The man 
 without ambition drifts about, looking at his world to-day 
 from one point of view, to-morrow from another. Abstrac- 
 tion is the most subtle and pervasive fact in individual life. 
 We all transform the worlds in which we live by the pur- 
 poses which control us in life. So absorbed do we become 
 in our personal points of view that it requires a serious jolt 
 to bring us back to the point where we are willing to make 
 revisions. 
 
 Language of great importance in furnishing central ideas. 
 The importance of language as an instrument of social ab- 
 straction will be instantly recognized in the light of what 
 has gone before. There are phrases current in language 
 which dominate personal thought and make our thinking 
 like that of our neighbors. Take such a word as ''effi- 
 ciency " ; the world is different to a man after he acquires 
 that word as a part of his working vocabulary. 
 
 The ineffectiveness of a detached verbal idea. The mean- 
 ing of these statements for individual development can 
 hardly be misunderstood. The practices of the schools in 
 making language subjects the center of the course of study 
 can be defended in the light of a psychological study of 
 language. To be sure there is danger in mere verbal 
 reactions. Language subjects in the schools need to be 
 brought back into relation with the practical activities of 
 life in order to insure the use of words as instruments 
 of real abstraction and social intercourse. Mere words may 
 be trivial, but words as guides to thought and as instru- 
 ments for the determination of abstractions are powerful 
 factors in controlling personal thought and action. 
 
 To the student who spends most of his time dealing 
 with books perhaps the warning in the last paragraph 
 should be made somewhat clearer. The cerebrum is so 
 complex in its structure that a tract may be established 
 
MENTAL HYGIENE 323 
 
 through its tissue, leading from the visual center directly 
 to the speech center. Words read will be repeated, but if 
 this short circuit alone is set in action, the process will 
 have to be described as one of mere repetition. 
 
 Higher organization as a cure for verbalism. The remedy 
 for mere verbalism is the development of larger systems of 
 behavior. The eye may see a long stick and the hand 
 may use this stick under the guidance of organized experi- 
 ence to pry up a weight. This reaction with the stick may 
 not arouse at all the speech tract above described, even 
 though the speech tract has been aroused by a textbook 
 in physics to repeat a passage about a lever. The indi- 
 vidual thus contains within his complex life one series 
 which is a series of reactions with a real lever and another 
 series which tells about levers. There is a possibility that 
 these two tracts existing side by side will not affect each 
 other in any way. The individual who is aware of this 
 dangerous type of separation of relatable activities within 
 himself will make a conscious effort to unite verbal reac- 
 tions with practical reactions. He will aim to set up a 
 higher internal organization including both speech and 
 hand adjustment. 
 
 A neglect of this demand for complete internal develop- 
 ment is one of the most serious dangers of our present-day 
 education. The real trouble is not that words in themselves 
 are bad or that handwork in itself is limited, but in the 
 rush of modern life the two are cultivated side by side and 
 neither gets the benefit of the other. What is needed is 
 a higher type of organization which will include the ver- 
 bal or theoretical discussion of levers and the illuminating 
 experiences that come from having levers in the hand. 
 This higher form of experience will bring to practical life 
 all the advantages of abstraction and to abstract life all 
 the advantages of concrete application. Both ends can be 
 reached in one and the same individual.' 
 
324 PSYCHOLOGY 
 
 Self-directed organization as the goal of the higher mental 
 life. Again we find ourselves speaking in terms of higher 
 forms of organization. Wherever the individual can compre- 
 hend in a single system of nervous or mental organization 
 more elements, there the adaptations of life and experience 
 will be broader and better. The lesson is clear. The indi- 
 vidual must seek of his own initiative those higher forms 
 of organization which will realize most fully the possibilities 
 of his life. 
 
 The highest level of individual organization is reached 
 when mental development becomes a matter of voluntary 
 control. Under the definition of volition which was worked 
 out in the last chapter it was seen that volition consists in 
 a control of action through intellectual prevision of results. 
 So it is also in the mental world. When the mind by self- 
 study sees the goal which self-development should reach, 
 it is possible by voluntary effort to move toward this goal. 
 Thus we have seen how knowledge of the nature of per- 
 ceptual attitudes may guide one in modifying these atti- 
 tudes. In like fashion, knowledge of the limitations of 
 study of theory may guide one in cultivating applications. 
 Knowledge of one's own limitations may lead to a per- 
 sistent attack upon these limitations. In short, voluntary 
 self-development means the cultivation of the broadest 
 possible systems of behavior. 
 
CHAPTER XVII 
 
 APPLICATIONS OF PSYCHOLOGY 
 
 Psychology a basis of scientific thinking about human 
 conduct. There are many phases of practical and scientific 
 thought regarding human activity which are illuminated by 
 the study of psychology. Indeed, wherever human nature is 
 a factor in any set of phenomena, there is need of a clear 
 understanding of the human contribution to the situation, 
 and this can be supplied in scientific form only by a study 
 of psychology. The complete demonstration of the useful- 
 ness of psychology would require a series of supplementary 
 chapters. It will be enough for our present purposes if the 
 general outlines of some of these discussions are presented. 
 
 Design in art as a psychological fact. Our first illustration 
 can be drawn from the field of the fine arts. This is a sphere 
 in which the relations of the individual to his external en- 
 vironment are relatively free. When the artist paints a pic- 
 ture, he is guided, so far as the design of his production is 
 concerned, by the laws of his own taste. Art grows out of 
 the demand for subjective satisfactions, not out of any com- 
 pulsion imposed by the physical world. It is for this reason 
 that psychology draws many of its best illustrations from the 
 sphere of art. If we find a general principle running through 
 art, we are led at once to the conclusion that there is a cor- 
 responding tendency in human nature. Certain simple illus- 
 trations may be offered. Thus, there is a certain proportion 
 between the long and short sides of rectangular figures which 
 is pleasant to look at. The proportion can be expressed mathe- 
 matically by saying that the long side is to the short side as 
 
 325 
 
326 PSYCHOLOGY 
 
 the sum of both is to the long side. If we examine those 
 objects which have been freely constructed without special 
 external limitations, we shall find that a great many of them 
 take on this proportion. For example, when an extensive 
 series of measurements was made of the two legs of orna- 
 mental crosses, it was found that they maintain the propor- 
 tion described. This fact can have no objective explanation 
 and must have been dictated by human subjective attitudes. 
 Freedom in art. Again, certain of the types of sym- 
 metry in architecture are efforts to meet the demands of 
 human nature rather than of external requirements. If we 
 examine the forms of architecture which grew up in a period 
 when men were free, so far as the external environment was 
 concerned, to construct buildings of any size which they 
 pleased, rather than to fit their constructions to the require- 
 ments of a city building lot, we find that the size and form 
 of these free buildings assumed certain general proportions 
 which were determined, not by the external conditions, but 
 rather by the demands of taste. Indeed, one of the funda- 
 mental distinctions between ancient and modern architecture 
 is a distinction which can be described by saying that the 
 early builders followed their sense of proportion, while modern 
 builders follow certain definite laws of mechanical construc- 
 tion. A Gothic cathedral of the pure type very commonly 
 exhibits certain irregularities in the position and size of its 
 columns, which yield in the mass an impression of solidity 
 and symmetry that could not be obtained if every part of the 
 building had been made to conform to exact mechanical rules. 
 A modern building is constructed with definite reference to 
 mathematical regularity of dimensions and with reference 
 also to the strain which is to be placed upon every given 
 part of its floors and walls. There is little tendency to 
 use the material freely ; there is much greater tendency to do 
 only what is necessary to meet the simpler mechanical re- 
 quirements. A column made of steel is designed to support 
 
APPLICATIONS OF PSYCHOLOGY 327 
 
 a certain weight, and the size of the column used in a build- 
 ing is usually determined by the weight which it is to carry 
 rather than by its appearance. The immediate effect of at- 
 tention to such mechanical requirements is that we have 
 many ugly buildings. 
 
 Architectural harmony analogous to musical rhythm and 
 harmony. There are many indications in the earlier, freer 
 architecture of the Greeks that they followed certain broad 
 principles of rhythmical proportion which correspond so closely 
 to what we find to be the principles of musical rhythm and 
 harmony, that there is a suggestion of a common type of 
 human organization lying back of both spheres of art. It has 
 been pointed out, for example, that the height of a Greek 
 column is an exact multiple of its diameter. Furthermore, the 
 space between the columns always stands in definite relation 
 to the diameter of the column. In details of construction 
 also, as, for example, in the various portions of the decora- 
 tions in the Ionic capital, the parts are related to each other 
 in definite unit ratios, so that a constructive symmetry runs 
 through the whole and gives the observer a feeling of com- 
 posure and unity. 
 
 Literary art and psychological laws. What is true of 
 architecture is much more obvious with reference to literary 
 art. It is clear that the laws of literary composition must be 
 laws of human nature, and the great artists have unquestion- 
 ably followed with sufficient closeness the demands of human 
 nature to leave their works as standards for future develop- 
 ment and as expressions of the direction in which all individual 
 development must tend. 
 
 Prose rhythms as related to the personal organization of 
 writers. Some purely formal indications of the complete- 
 ness with which great literature conforms to the demands of 
 human nature may be found in the fact that there are even 
 in prose compositions certain typical rhythms which give to 
 these compositions a regular symmetry of character, which 
 
328 PSYCHOLOGY 
 
 undoubtedly constitutes one of its charms. It is a striking 
 example of the fact that art may outstrip science, that it is 
 not yet possible to give any complete theoretical account of 
 the prose rhythms of the best writers. Evidently those who 
 have contributed the great works to literature have succeeded 
 in utilizing the language in which they wrote in such a way 
 as to express an internal organization of their own which was 
 altogether appropriate to their theme and to the vernacular, 
 and this they have done spontaneously and very often without 
 complete theoretical recognition of what they were doing. 
 When the student of such prose arrives by laborious analysis 
 at some knowledge of the rhythms which it contains, he is 
 not creating rhythms, but rather rediscovering by the tardy 
 methods of scientific analysis a formula which has been 
 achieved by the great writer through intuition. 
 
 Verse another example of the same type. If the forms 
 of prose composition have exhibited complexity of structure, 
 together with a fundamental regularity of form, it is even 
 more true of verse that its masters have never followed rigid 
 mechanical principles in their work. And yet they have ade- 
 quately met the demands of human nature. Their conformity 
 to a limited group of principles is seen in their adherence to 
 certain regular forms which are sufficiently obvious to be imi- 
 tated in gross outline by writers of less taste and power ; but 
 the full and effective use of verse forms has always involved 
 a certain freedom of manipulation which has defied any com- 
 plete theoretical account. Psychology must frankly admit in 
 such a case as this that it follows in the steps of a complete 
 adaptation, very far behind the adaptation itself. Neverthe- 
 less, the psychological problem is clear, and a general sug- 
 gestion as to the explanation of these. facts may be found in 
 what has been said in an earlier connection regarding the 
 nature of rhythm. Whatever the unknown details, rhythm 
 is certainly in keeping with the natural demands of the nerv- 
 ous system. Because the nervous system is rhythmical in a 
 
APPLICATIONS OF PSYCHOLOGY 329 
 
 complex way in its own functioning, it responds favorably to 
 rhythms of impressions. 
 
 Literary content controlled by psychological laws. It is 
 not alone in its form that literature expresses the demands 
 of human nature ; the content may be studied from the same 
 point of view. It is possible by a psychological'-a:nalysis to 
 throw much light on one case which te^>^been the subject of 
 much mystical speculation. It has often been suggested that 
 human intuitions and vague feelings frequently bring us much 
 nearer to that which afterward proves to be the truth than do 
 our most elaborate processes of reasoning. The poet has 
 always claimed for himself a higher position than he would 
 allow to the scientist who is bound by the demands of rigid 
 evidence. We often speak of the insights of the artist, and 
 mean by this phrase that the artist sees beyond the ordinary 
 facts of definite observation and clear vision to ranges of facts 
 which are of importance, but are not open to our inspection. 
 
 Feeling and intuition. What has been said in an earlier 
 chapter with regard to the nature of feelings will be of some 
 assistance in clearing up the paradox which here appears. 
 When explaining the feelings, we discovered that whatever 
 runs counter to the organized nature of the individual will 
 arouse a disagreeable feeling. Whatever is in fundamental 
 agreement with nature will give pleasure. If now the ex- 
 periences of life are in subtle agreement or disagreement 
 with the organization of the individual, it does not follow 
 that the individual will become clearly conscious of this fact 
 in ideational or abstract terms, and yet he may be vividly 
 aware of the disagreeable feeling imposed upon him by a 
 certain experience. For example, as we have seen in earlier 
 discussions, the organization of an animal may be such that 
 certain color stimulations are fundamentally opposed to its 
 natural organization. Feeling is, therefore, a kind of spon- 
 taneous adjustment with a practical value which often sur- 
 passes that of incomplete theoretical judgments. Feeling 
 
330 PSYCHOLOGY 
 
 may be relied upon in those situations where the organiza- 
 tion is simple enough or the response direct enough to 
 give an unbiased reflection of the individual's relation to the 
 impression. On the other hand, when life becomes complex, 
 as it is in human beings, native instincts and native feelings 
 are often overlaid by a series of developments so indirect 
 that there comes to be a certain rivalry between the author- 
 ity of feeling and the authority of abstract knowledge. 
 There can be no doubt, for example, that the social selec- 
 tions by which one determines who shall be his friends are 
 dependent in large measure on intuitions, but one does not 
 need to be very old or worldly-wise to recognize that the 
 complexities of social life are such that the instinctive feel- 
 ings which we have in making the acquaintance of new 
 individuals are not always safe guides in the development 
 of social relations. What is true of social relations is true, 
 undoubtedly, of artistic intuitions and of larger intuitions of 
 universal truth. It is quite impossible to persuade one who 
 regards a line of poetry as beautiful that it is not beautiful 
 because it violates some rigid law of versification. It is 
 quite impossible to convince one who enjoys a certain pic- 
 ture that the picture is deficient because it does not comply 
 with certain canons of a certain school of art. On the other 
 hand, it is frequently possible, by a series of educative con- 
 tacts with better artistic and literary forms, gradually to 
 modify an individual's organized feelings so that he shall 
 completely change the character of his judgment. Intuition 
 is, therefore, not a separate and distinct faculty of life ; it is 
 rather an expression of that immediate form of recognition 
 of congruity or incongruity which characterizes the feelings 
 as distinguished from abstract theoretical knowledge. The 
 statement made by the poet may express an attitude which 
 is true to the facts and will later be fully explicated by the 
 clearer ideational view cultivated in abstract thought. There 
 is no ultimate opposition between feeling and thought. 
 
APPLICATIONS OF PSYCHOLOGY 331 
 
 Many of the social sciences predominantly objective in 
 their methods. When we turn from the discussion of art 
 and feeling to certain more practical spheres of investigation 
 involving human nature, — namely, those taken up in the 
 social sciences and anthropology, — we find that the study of 
 psychology is very direct in its application to these spheres 
 of study and explanation. It has not always been fully 
 recognized that psychology has a relation to the social 
 sciences. Certain schools of social scientists have treated 
 the institutions which they study merely as objective facts. 
 To show this, we may take as an illustration one of the 
 oldest of social sciences ; namely, the science which deals 
 with language. Language is a product of human activity 
 which has a sufficiently independent existence to make it 
 an easy subject for examination and analysis. To trace the 
 history of a word is to undertake an investigation which 
 calls for little reference to the individuals who may have 
 made use of this word. In like fashion, the study of a sys- 
 tem of sounds and written symbols may result in the dis- 
 covery of certain regularities and laws of phonetics without 
 reference to the human beings who used this language and 
 who were the ultimate sources of regularities in the lan- 
 guage itself. The same historical and objective methods 
 have been applied to the study of other institutions. For 
 example, religious systems have been described and their 
 uniformities and divergencies have been ascertained without 
 more than a passing reference to the individuals who 
 developed these systems or adhered to them. 
 
 Introspective psychology and its limited support to social 
 science. The tendency to confine attention to an objective 
 study of human institutions has been strengthened by the 
 attitude which for a long time prevailed in psychology, when 
 the chief method of investigation was the introspective 
 method, according to which the individual attempted to dis- 
 cover the laws of mental life through an examination of 
 
332 PSYCHOLOGY 
 
 his own immediate experience, and with very Uttle refer- 
 ence to the modifying influence of his fellow beings or the 
 secondary factors of his environment. When the problem 
 of psychology is more broadly conceived, so that it is seen 
 that the character of human mental life can be defined only 
 by a more elaborate study of numerous examples and ex- 
 ternal relations, the spheres of institutional study and of 
 psychological investigation are gradually brought nearer to 
 each other. 
 
 Interrelation of psychology and social science. In the 
 course of recent psychological study, much valuable illus- 
 trative material has been borrowed from the sciences which 
 deal with language and from anthropology. Psychology has 
 thus expanded under the influence of the new body of 
 material which has been adopted into it. The methods of 
 psychology have become more objective, and the results 
 of individual introspection have been broadened. On the 
 other hand, the scientific study of all other human beings 
 m.ust be based upon one's own personal experiences. One 
 naturally thinks of primitive man in terms of his own men- 
 tal experiences. If there is no scientific study of the matter, 
 the student is likely to carry over analogies and apply them 
 to cases where they do not illustrate, but rather obscure, 
 the truth. Thus, as has been pointed out by a recent writer, 
 there is a widespread tendency to describe the mental abili- 
 ties of savages by means of a succession of negatives. Savages 
 do not count, they do not have a full series of color terms, 
 they do not paint pictures or write. All these negatives 
 are mere expressions of the natural tendency to accept our- 
 selves as standards. We should become sufficiently imper- 
 sonal in our studies to recognize that savages probably have 
 a nicety of space perception which is very much greater 
 than ours. They may not select color qualities and name 
 them, but for the finer grades of variation in plant and 
 animal life as indicated by color they have the most highly 
 
APPLICATIONS OF PSYCHOLOGY 333 
 
 developed discrimination. Not only the savage, but even 
 our contemporaries in different civilizations from our own, 
 are exceedingly baffling unless we make some study of their 
 types of mental development. The institutions of Tibet, 
 China, and Japan are obviously different from our own, but 
 the character of the mental processes back of these insti- 
 tutions has been little thought of and little studied. The 
 careful scientific study of the mental characteristics of 
 different peoples is one of the most promising lines of 
 extension of psychological study. 
 
 Human evolution psychical. So intimately is social 
 organization bound up wdth the mental development of the 
 individual that we are justified in the statement that psychol- 
 ogy is the basis of any explanatory account of social insti- 
 tutions. There is one particular anthropological problem 
 where the significance of psychological analysis can be 
 made very clear. Anthropology has never succeeded in 
 finding structural modifications in the human body which 
 would at all adequately account for the great superiority of 
 highly developed races over the more primitive tribes of 
 mankind. Even the explanation of the crucial development 
 by which man became differentiated from the animals is 
 one of the obscure chapters in anthropology. It cannot be 
 denied that the explanation of all these matters must be 
 sought in terms which refer to the development of intelli- 
 gence, especially the development of language and the use 
 of tools, as has been indicated in an earlier discussion. 
 The problem of anthropology^ is thus distinguished from 
 the purely biological problem, w^here intelligence is not rec- 
 ognized as playing any part. How could a certain group of 
 animals suddenly break away from the established type of 
 evolution in which changes in structures played a large part 
 and become animals characterized by intelligence, meet- 
 ing the emergencies of their lives by a mental adaptation 
 of themselves rather than by a purely physical adaptation ? 
 
334 PSYCHOLOGY 
 
 Why should this group of animals turn to the develop- 
 ment of all the instruments of civilization ? The problem 
 stated in this form becomes a problem of functional de- 
 velopment rather than a problem of physical development. 
 This animal must have been driven at some time into a 
 situation where his development turned upon his ability 
 to adopt a new type of behavior and a new mode of life. 
 There can be no doubt that the scientific explanation of 
 the breach between man and the animals depends upon 
 the recognition of a transformation in the mode of behavior 
 and mental life rather than upon any fact of gross bodily 
 change. Put in another way, the statement may be made 
 that we need no animal form to serve as a connecting 
 link between man and the animals. The common struc- 
 ture, the common physical needs of man and the animals, 
 are now made out so fully that what science requires is an 
 explanation of the gap, rather than the link, between man 
 and the animals. The doctrine of biological evolution has 
 successfully established the principle of continuity. It re- 
 mains for genetic psychology to explain the discontinuity 
 which appears when intelligence begins to dominate, when 
 sensory-motor adjustments of the reflex and instinctive type 
 give place to habit acquired through individual intelligence 
 and to the more elaborate forms of thought. 
 
 A hypothesis to explain the break between man and 
 the animals* An interesting hypothesis has been suggested 
 which illustrates the possibility of assuming a distinctly func- 
 tional attitude toward the question of the evolution of man. 
 This hypothesis suggests that the gradual changes in physi- 
 cal organization which characterize all of the different species 
 of primates lead up to the appearance of man only because 
 at one time a number of these primates were forced, prob- 
 ably by the emergencies of a glacial climate in certain quar- 
 ters in which they were confined, to adopt a mode of life 
 which brought them down out of the trees and forced upon 
 
APPLICATIONS OF PSYCHOLOGY 335 
 
 them types of activity which led to their construction of arti- 
 ficial shelters and to the preparation of forms of food which 
 had not been previously utilized by their race. The change 
 here assumed depends on the rise of a powerful motive for 
 new ways of behavior. Whatever change there was in the 
 individual consisted in the opening of new paths in the cen- 
 tral nervous system. This change in the trend of evolution, 
 when once it appeared, was so important that the further 
 history of the group of animals which succeeded in effecting 
 it was in the direction of adaptation through intelligence 
 and nervous organization rather than through gross changes 
 in bodily structures. Whether we give any credence to this 
 hypothesis or not, it expresses admirably the functional atti- 
 tude in the explanation of human evolution. It expresses 
 clearly the fact that the nature of mental and functional 
 adaptation is the significant problem for anthropology rather 
 than the mere search for changes in physical organization ; 
 it gives to anthropology a definite impetus in the direction 
 of the study of mental organization, as distinguished from 
 the study of bodily structures. 
 
 Spencer's application of psychology to sociology. Another 
 illustration from a later period of human development which 
 will also emphasize the significance of psychological study 
 for anthropology is to be found in Spencer's discussions, in 
 which he calls attention to the fact that the growth of civili- 
 zation depends upon the broadening of the individual's men- 
 tal horizon. He points out the fact that the savage who had 
 interest in only a small range of territory and the present 
 enjoyment of objects immediately about him gradually de- 
 veloped into the semicivilized man interested in a larger 
 territory, a larger number of individuals, and a longer period 
 of time. The planting of crops and the erection of perma- 
 nent buildings cannot be explained by objective conditions 
 as has sometimes been attempted in the history of civiliza- 
 tion. There must be ideas and imaginations in the mind of 
 
336 PSYCHOLOGY 
 
 some active being before the future can be anticipated suffi- 
 ciently to lead to the planting of the crop or the erection 
 of the building. 
 
 Relation of educational practices to scientific psychology. 
 
 Conspicuous among the social institutions to which psychol- 
 ogy may be applied in a direct and practical fashion is the 
 institution of education. Here again is a type of adaptation 
 which has grown in an unscientific way to a high degree of 
 maturity. This statement implies no disposition to deny the 
 effectiveness of many of the practices of educational institu- 
 tions. They may be effective without being scientific. They 
 are the outgrowth of a need which has been felt by every 
 generation, and the educational institutions which have been 
 developed in response to this general need have been refined 
 and modified in view of experience, until finally they express 
 with a high degree of perfection the final judgment of many 
 generations upon important questions connected with the 
 training of the younger generation. Yet there are obvious 
 reasons why these historical institutions should be reexam- 
 ined. Some of the uncritical methods of education are found | 
 to be wasteful ; again, the educational practices of different 
 peoples or different sections of the same nation are found i 
 to be inharmonious. There arises, therefore, a demand for 
 a careful analysis of the whole situation and the establish- 
 ment of those practices which scientific analysis can justify. 
 It is true that many hold the same attitude with regard to 
 education that they do with regard to art ; namely, that it is 
 safer to rely upon the intuitions of human feeling than to 
 attempt to formulate an abstract system of education. Those 
 who adopt this position with regard to the advantages of in- 
 tuition in education have justification for their position, in 
 so far as educational practices are refined to a point beyond 
 our knowledge of the laws of human development. The 
 most acceptable plea for a scientific study of education which 
 could be presented to such persons would consist in a plea 
 
APPLICATIONS OF PSYCHOLOGY 337 
 
 for a more complete knowledge of the same sort which they 
 have in their native intuitions. It might be said, for exam- 
 ple, that the study of educational methods involves nothing 
 more than the bringing together of the individual experi- 
 ences and practices of all those who have become skilled in 
 educational practice. A comparative study would help to 
 eliminate those individual intuitions which are incorrect, 
 because they are based upon too narrow experience. 
 
 Psychology as a preparation for the intelligent diagnosis 
 of particular situations which arise in educational practice. 
 The final examination of educational practices must go much 
 further, however, than is implied in this appeal for a com- 
 parative study of intuitions. Attention must be called to the 
 fact that much of our devotion to traditional educational prac- 
 tices is nothing more or less than a deliberate confession of 
 our ignorance of the way in which the human mind develops. 
 When a teacher is confronted by children who are unable 
 to comprehend the lesson which has been set, he very com- 
 monly can make no analysis of the child's difficulty. He 
 then covers up his ignorance of the step which should be 
 taken by requiring repeated efforts on the child's part, until 
 in some unknown fashion the difficulties are mastered. It 
 does not follow that the particular difficulty encountered in 
 any given case would have been recognizable if the teacher 
 had made a study of human development in other individ- 
 uals, but the probability that the trained teacher will be able 
 to make a scientific analysis of the difficult situation at hand 
 is increased if he becomes acquainted with the principles 
 and results of scientific psychology. Intuition should there- 
 fore be supplemented by as full an account as can be given 
 of the way in which mental processes go on and of the 
 methods by which these processes may be examined. 
 
 A few illustrations may serve to make clear the place 
 and value of the psychological study of educational prob- 
 lems. First, a number of investigations have recently been 
 
338 
 
 PSYCHOLOGY 
 
 undertaken with a view to defining in detail the course of 
 development of certain habits. Broadly stated, the conclu- 
 sions of these studies show that no habit develops in all of 
 its stages at a uniform rate. There is at the outset a period 
 during which improvement is relatively very rapid ; this is 
 followed by a period of slow development, which in turn 
 gives way to successive periods of rapid and slow growth. 
 
 
 4 
 
 Weeks of Fractice 
 8 12 16 20 24 
 
 28 
 
 32 
 
 36 
 
 40 
 
 i 
 
 i l. 1 I I 
 
 i 
 
 i 
 
 1 
 
 
 ,140 
 130 
 
 — 
 
 Seri£2x~^ 
 
 
 — ^ 
 
 
 
 120 
 ■§110 
 
 lioo 
 
 ? 90 
 
 a, 80 
 
 CO 
 
 ^ 60 
 
 ^ 50 
 
 40 
 
 — 
 
 /"^ Slowest Main Line Bate / 
 
 r^ 
 
 ^ 
 
 
 -^ 
 
 — / 
 
 
 
 
 
 
 30 
 
 - / 
 
 
 
 
 
 
 20 
 
 - } y^ 
 
 
 
 
 
 
 10 
 
 / y 
 
 
 
 
 
 
 Fig. 6o. Curves for sending and receiving telegraphic messages 
 
 The curve is pubHshed by Bryan and Harter. The number of weeks of practice is 
 
 indicated in the upper part of the figure. The number of letters v/hich can be 
 
 received and sent in a minute is represented in the vertical. The figure is divided 
 
 by a horizontal line, which shows the standard rate 
 
 A curve illustrating the process of learning. One of the 
 
 earliest investigations of the way in which an individual 
 learns may be described in detail. This investigation was 
 undertaken to determine the rate at which a learner acquired 
 the ability to send and receive telegraphic messages. The 
 selection of this particular case for the test was due to the 
 ease with which measurements of proficiency could be made 
 and to the maturity of the persons investigated, which made 
 it easy to subject them to a series of tests. In Fig. 6o the 
 
APPLICATIONS OF PSYCHOLOGY 339 
 
 results of the investigation are represented in a curve. Along 
 the top of the figure are marked the successive weeks during 
 which the investigation was carried on ; along the vertical 
 line at the left the number of letters which could be received 
 or sent in a minute. A single point on the curve repre- 
 sents, accordingly, both a stage in the practice series and 
 the number of letters which could be received or sent dur- 
 ing a minute at this stage of development. The curves taken 
 in their entirety represent the gradual increase in the ability 
 of the subject. It will be noticed, in the first place, that the 
 improvement in sending and in receiving messages followed 
 an entirely different course, both with reference to rate of 
 improvement and also with reference to the successive stages 
 of development. Concentrating attention for the moment 
 upon the curve which records improvement in receiving, 
 we see that the development is at first rapid and then for a 
 long time practically stationary. After the stationary period, 
 or plateau as the authors called this part of the figure, came 
 a second rapid rise in the curve. 
 
 Significance of a ''plateau" in development. In Fig. 61 
 a second curve of the same sort is shown, w^hich makes it 
 possible to explain the pause, or plateau, in development. 
 The lowest curve in this second diagram represents the 
 development of proficiency in recognizing isolated letters. 
 The second curve represents the development of proficiency 
 in receiving isolated words which did not unite into sentences, 
 and the full curve represents, as before, the development of 
 efficiency in receiving words which constituted sentences. It 
 will be noticed that the ability to receive isolated letters and 
 the ability to receive isolated words developed rapidly for a 
 time, until they reached their maxima, and then they con- 
 tinued indefinitely at the same level. This level is so related 
 to the plateau in the total curve that the plateau can safely 
 be defined as the period during which the subject was in 
 the word stage of development, rather than in the sentence 
 
340 
 
 PSYCHOLOGY 
 
 stage. Only after the ability to receive single words had 
 been thoroughly matured was a new type of development 
 possible. 
 
 Other examples of the same type of development. Such 
 an analysis as this of a case of learning shows much with 
 regard to the psychological character of the process. It also 
 
 108 
 
 96- 
 
 <J3f 
 
 "§ Sir 
 
 
 0) 
 
 36 
 
 24 
 
 
 
 .12 
 
 Weeks of Practice 
 16 20 24 
 
 33 
 
 Slowest Maim Line Bate 
 
 Fig. 6i. Analysis of the receiving curve 
 This figure is similar to Fig. 6o. For further discussion, see text (p. 339) 
 
 suggests the possibility of including the process of mental 
 development under certain broad laws of development. 
 There are many analogous cases in general evolution where 
 it has been noted again and again that periods of rapid 
 development are followed by long periods of assimilation. 
 It is a well-known fact of bodily growth that the enlarge- 
 ment of the body is most marked at certain periods in the 
 year and at certain well-defined periods in the child's life. 
 After one of the sudden enlargements of the body, there 
 follows a period of gradual assimilation of the new develop- 
 ments, during which the body remains stationary in its size 
 
APPLICATIONS OF PSYCHOLOGY 341 
 
 for a considerable time. The facts of organic evolution on 
 a larger scale are of the same type. During certain periods 
 the animal kingdom has advanced rapidly by the production 
 of new forms, after which long stationary periods appear, 
 during which these new forms are more completely adjusted 
 to their environment without being in any important sense 
 modified. Such statements as these make clear the distinc- 
 tion between assimilation and acquisition in both the physical 
 and mental worlds. 
 
 The fact that certain forms of mental development are 
 periodic rather than continuous is illustrated in many cases 
 where quantitative tests have not been made. It has often 
 been casually observed that a mature subject learns a foreign 
 language, not with uniform rapidity, but in a way analogous 
 to that shown in the curves given above. At first there is 
 rapid acquisition of the words and grammatical constructions 
 of the new language, but after a time the power to acquire 
 new phases of the language seems to be brought to a stand- 
 still, and the period of discouragement which follows is 
 often felt by the learner to be a period of no development, 
 while in reality it is a period of assimilation and preparation 
 for the later stages of growth. When the later development 
 into the full use of the language comes, it is so sudden and 
 striking in its character that it has been noted time and time 
 again as a period of astonishing mental achievement. 
 
 Motor habits intermittent. Many habits of action exhibit 
 the same type of intermittent development. If one learns 
 some manual art, he finds that the incoordinations with 
 which he begins are only gradually eliminated ; but finally he 
 learns the combination which is advantageous, and from that 
 point on the improvement seems for a time to be very rapid. 
 It is sometimes advantageous in a course of training to give 
 up practice for a time in order that the various elements of 
 the coordination may have an opportunity to readjust them- 
 selves and in order that the new efforts at development may 
 
342 PSYCHOLOGY 
 
 begin at a new level. Professor James has made the striking 
 remark that we learn to skate during the summer and to swim 
 during the winter. The significance of this observation is 
 that it recognizes the intermittent character of the develop- 
 ment of habit and the advantage of a period of assimilation, 
 sometimes even of a period of complete cessation of the 
 activity in question. 
 
 School training in its relation to the stage of development 
 attained by the mind. From the point of view of practical 
 education, it is obvious that the types of training which 
 should be given at the different periods in mental develop- 
 ment are by no means the same. During a period of rapid 
 acquirement of new material, one sort of training is appro- 
 priate ; during a period of delayed assimilation, that form 
 of training is most appropriate which is technically known 
 in the schools as drill. The ordinary unscientific education 
 has recognized vaguely that there is. a difference in the 
 kinds of training demanded at different times ; but the ad- 
 justment of these different types of training to the demands 
 of individual mental development is an intricate problem 
 which can be worked out satisfactorily only when a careful 
 study is made of educational practice. 
 
 Significance of scientific studies often indirect. The value 
 of scientific studies of habits and of forms of training is 
 shown by such considerations as the foregoing. It also 
 becomes evident that such studies do not necessarily change 
 the subjects of instruction nor even the general methods 
 established by tradition, but serve rather to refine our knowl- 
 edge of the process of mental growth and make it possible 
 for us to deal with different stages of the educational process 
 with much greater precision. To justify scientific investiga- 
 tions which seem at first sight remote from school problems, 
 it may be well to point out that the solution of one problem 
 in mental development makes it possible to attack all other 
 problems of a similar kind more intelligently. If one knows 
 
APPLICATIONS OF PSYCHOLOGY 343 
 
 with scientific precision that a period of assimilation occurs 
 in one case of mental development, he will be better pre- 
 pared to discover and understand a similar period in other 
 cases where it may be less easy to make an exact scientific 
 study. For example, w^e get useful suggestions to guide us 
 in understanding children's reading from the study reported 
 above on learning telegraphy. The mastery of the word ele- 
 ments in ordinary reading is similar to the mastery of these 
 same elements in the case of the telegrapher. 
 
 Expression as an essential condition of mental life. An- 
 other concrete illustration of educational progress may be 
 found in the fact that there is a general disposition among 
 educators to-day to recognize the importance and value of 
 expressive activities in all educational processes. The early 
 type of education was that in which sensation processes were 
 emphasized almost to the exclusion of activities. Whether 
 the educational practice w^hich emphasized impressions can 
 be attributed to the sensation psychology which was contem- 
 porary with it, or w^hether the sensation psychology was the 
 outgrowth of a false educational theory, is a question which 
 need not be discussed here. Certain it is that the limited 
 view of mental life and the false principle of education, both 
 of which emphasized impressions rather than expression, 
 existed for a long period side by side. It may have been 
 the growing experience of practical teachers which led to 
 the discovery of the fallacy in the doctrine that mind is 
 conditioned primarily by impressions. It may have been 
 the insight of scientific students which gradually made it 
 clear that human activity must always be recognized in dis- 
 cussing the processes of mental development ; or it may be 
 that the two lines of thought and practice grew up together. 
 In any case, it is certain that a transformation of educational 
 practice and a corresponding transformation of psycholog}^ 
 have been going on for a generation, until now we have 
 in both an emphasis on bodily activities. 
 
344 PSYCHOLOGY 
 
 Psychology historically a part of philosophy. Turning 
 from these practical applications of psychology to education, 
 it remains for us to discuss one of the applications of psy- 
 chology which has always been recognized in the historical 
 development of this science ; namely, the relation of psy- 
 chology to the philosophical disciplines. Indeed, it may be 
 said that psychology was not only applied to the problems 
 of philosophy ; it was originally devoted to the discussion of 
 these problems to such an extent that it vs^as regarded as an 
 integral part of philosophy, not as an independent science. 
 Philosophy deals with the ultimate nature of matter and 
 mind, with the fundamental laws of reality and the relation 
 of reality to human experience, with the ultimate nature of 
 truth, goodness, and beauty. There have been times, for 
 example during the medieval period, when the interest in 
 such ultimate problems ran so high that there was little or 
 no attention given to the special problems of science. The 
 time came, however, with the development of modern 
 thought when these larger problems receded into the back- 
 ground and men began to concern themselves with the 
 phenomena in the world rather than with the ultimate reali- 
 ties underlying these phenomena. It is characteristic of the 
 present scientific period that the special sciences neglect 
 to as great an extent as possible the questions of ultimate 
 reality. The student of psychology participates to a very 
 large extent in this tendency to omit from his discussion 
 questions relating to the ultimate nature of mind. He 
 cannot, however, accept as final this aloofness from the 
 broader questions, for he finds himself, more than his 
 neighbor who deals exclusively with the natural sciences, 
 led to ultimate problems. 
 
 Relation of psychology to philosophy closer than that of 
 any of the special sciences. When, for example, one points 
 out that a sensation is related to a fact of external energy 
 indirectly through the organs of sense, or when one points 
 
APPLICATIONS OF PSYCHOLOGY 345 
 
 out that space is a definite form of perception on the one 
 hand, and of arrangement of objects on the other, the 
 psychologist is driven to consider the relation between con- 
 sciousness and the external world more than the student of 
 the other particular sciences. The student of natural science 
 uses in every act of observation the relation between subjec- 
 tive experience and the physical world ; he exercises his 
 mind in trying to know the world, but his interests are 
 always centered on the relations between things, never on 
 the relation between things and consciousness. Hence the 
 student of natural science easily avoids questions relating 
 to the ultimate interaction between himself and the physical 
 world. The student of psychology cannot escape these 
 questions. His study of sensation pushes him in the direc- 
 tion of an examination of this relation. F'urthermore, when 
 the student of psychology finds that the construction of 
 concepts is an elaborate mental activity, he is immediately 
 led to ask not only what are the laws which control such 
 conceptual activity, but also what are the relations of scien- 
 tific ideas to external reality, and what are the laws which 
 determine the validity or lack of validity of these concepts. 
 It is true that psychology cannot answer all of these ques- 
 tions, and it has been our purpose in the foregoing discus- 
 sions to adhere as closely as possible to the sphere of strict 
 psychological inquiry, postponing these ultimate questions 
 or entirely omitting them. It is, therefore, very appropriate 
 that we should call attention at the end of our inquiry to 
 the disciplines which deal with these more elaborate inquiries, 
 and that we should define their relation to psychology. 
 
 Psychology and logic. Logic attempts to formulate the 
 laws of valid reasoning. To be sure, logical principles can 
 be worked out without the aid of psychology, through 
 repeated efforts to reason correctly, but the clear definition 
 of logical relations waits on the psychological descriptions 
 of the mental processes involved in reasoning. 
 
346 PSYCHOLOGY 
 
 Psychology and aesthetics. The second branch of phi- 
 losophy is aesthetics. In earlier chapters reference has 
 been made repeatedly to the underlying principles which 
 control the recognition of symmetry and regularity of form, 
 and it was pointed out in earlier paragraphs of this chapter 
 that the canons of architecture and painting are directly re- 
 lated to certain fundamental principles of human feeling and 
 recognition. There still remain a large number of special 
 analyses and special considerations which must be worked 
 out in order to define fully the canons of taste in each field 
 of art and the general canons of taste which underlie all 
 forms of art. Such considerations of the canons of art 
 constitute a legitimate development of the general psycho- 
 logical studies which have been suggested, and constitute 
 the special discipline of aesthetics. 
 
 Psychology and ethics. When we turn to the third of 
 the special philosophical disciplines, namely ethics, we find 
 again a natural relation to psychology, though it is perhaps 
 proper to emphasize here more than in the case of logic or 
 aesthetics the independence of ethical canons from purely 
 subjective organizations. The rightness or wrongness of 
 human behavior is not understood primarily through an 
 analysis of the processes of behavior themselves. The 
 rightness or wrongness of behavior depends upon certain 
 broad considerations involving the social interrelationships 
 of the active individual. It is necessary, therefore, to make 
 a study of the extra-mental or social relations of the indi- 
 vidual in order to establish the canons of ethical conduct. 
 One does not need to discuss the extra-mental relations to 
 anything like the same extent when he attempts to define 
 the laws of reasoning in logic or the laws of appreciation 
 in aesthetics. It is true that the individual's modes of be- 
 havior, as they have been worked out in the course of 
 social life, come to embody much of the social interrelation- 
 ship which determines their ethical validity. The individual 
 
APPLICATIONS OF PSYCHOLOGY 347 
 
 who has grown up in a social group ultimately conforms 
 in his modes of thought and internal organization to those 
 social demands which are imposed upon him by the com- 
 munity in which he lives. It is probably true, therefore, 
 that in the last analysis the fundamental truths of ethics 
 are expressed in the internal organization of the individual 
 as well as in the forms which are approved under the 
 canons of social life, but the development of ethical laws 
 lies somewhat beyond the application of psychology. We 
 come to ethics chiefly through the study of the applications 
 of psychology to the sciences of social institutions. 
 
 Psychology and metaphysics. When we turn from the 
 special philosophical disciplines to the broader field of meta- 
 physics, or the general theory of reality, we find that the 
 relation of psychology to these broader types of considera- 
 tion is relatively indirect. Metaphysics takes up the results 
 of natural science which deals with matter and of psycho- 
 logical science which deals with consciousness, and attempts 
 to formulate some general principles of the relations between 
 all forms of reality. To this general discussion psychology 
 cannot contribute final answers any more than could the 
 special sciences of physics or chemistry. Psychology can 
 only present its conclusions after it has carried out as com- 
 plete an analysis of consciousness as possible, and must 
 leave it for metaphysics to make an ultimate comparison of 
 these facts with the physical facts. The student who finds 
 that an empirical analysis of consciousness conflicts with 
 any of the established views which constitute a part of his 
 general theory of the world should recognize that it is not 
 the function of any single science to reconstruct his total 
 theory of the world. He will have to accept the results of 
 empirical analysis in all the different spheres of exact 
 research and work out a general view which will include all 
 of these results. The conclusions of psychology need to be 
 generalized exactly as do the conclusions of physics and 
 
348 PSYCHOLOGY 
 
 chemistry. No generalization will be finally valid which 
 does not comprehend the empirical analysis of each one of 
 these sciences. Furthermore, it should not be forgotten 
 that there are many types of consideration which forced 
 themselves upon human attention long before the various 
 forms of scientific analysis could be worked out, and these 
 considerations must also be recognized in the construction 
 of a broad philosophy of life. The generalizations which 
 were reached before the development of the special sciences 
 require revision in order to include the results of these 
 sciences. This fact should not disturb the mind of any 
 student and need not lead him to ignore many nonscientific 
 types of experience. The training in scientific inference 
 which he has received in the study of empirical psychology 
 should lead him to recognize that all generalizations are 
 subjective constructs built up from a great variety of experi- 
 ences, many of which are superficially in disagreement with 
 each other. The subjective construct is not to be discarded 
 as invalid, because it changes with the acquisition of new 
 knowledge ; one's theory of the world must change in order 
 to fulfill its function as a complete, organized expression of 
 the manifold experiences which enter into life. Psychology, 
 more than any other science, should lead to a recognition 
 of this demand for a constantly progressing enlargement of 
 philosophic view. While, therefore, modern psychology as a 
 science has freed itself from the obligation of dealing with 
 the broad philosophical questions, it continues, when rightly 
 understood, not only to contribute material for philosophic 
 thought, but also to urge the student to the rational recon- 
 struction of his general abstract views. It is therefore intro- 
 ductory, not merely to the special philosophical disciplines 
 but also to the more remote discussions of metaphysics itself. 
 
INDEX 
 
 x\bnormals, psychology of, ii 
 Abstract words, 236 
 Abstraction, 232, 263 
 Accommodation, 86 
 Achromatic sensations, 74 
 Action, voluntary, 301 
 
 and words, 235 
 Active organs, glands as, 138 
 
 muscles as, 134 
 Adaptation, conscious, 4 
 
 human, and ideas, 251 
 Aerial perspective, 184 
 Esthetics, 346 
 
 After-effects of hypnosis, 295 
 After-images, auditory, 114 
 
 table of, 100 
 
 visual, 94 
 Agreement, internal, as test of im- 
 agination, 257 
 Alcohol, 285 
 
 Alligator, nervous system of, 31 
 Alphabet, blind, 167 
 
 evolution of, 222 
 Altruism, 151 
 
 American Crowbar Case, 58 
 Amplitude, 78 
 
 of vibrations, 78 
 Anaesthesia in hypnosis, 290 
 Analysis, perceptual, 316 
 
 scientific, of consciousness, 65 
 Analytical psychology, v 
 Anger, 152 
 Angier, R. P., vii 
 Animal language, 212 
 Animal psychology, 10 
 Animals, unicellular, 15 
 Anthropology and psychology, 333 
 Aphasia, 56 
 
 Apparatus in, experiments, 8 
 AppHcation and verbalism, 323 
 Applications of psychology, 69, 325 
 Aqueous humor, 85 
 Arabic iiumerals, 229 
 Architectural harmony, 327 
 
 Arithmetic, development of, 229 
 Armstrong, A. C, vi 
 Art, 325 
 
 freedom in, 326 
 Articulation, selection of, 214 
 Association, 245 
 
 principle of, 59 
 Association area, Broca's, 57 
 Association areas, in cortex, 50, 
 
 52, 53 
 
 frontal, 58 
 
 in human cerebrum, 54 
 Association centers, 29 
 Atom, concept of, 262 
 Attention, 62, 156, 160 
 
 and gesture, 216 
 
 involuntary, 303 
 
 voluntary, 301 
 Attitudes, 66, 69, 142, 233 
 
 control of, 319 
 
 external, 155 
 
 fundamental, 146 
 
 ideational, 254 
 
 mental, 207 
 Auditory area in cerebrum, 52, 53, 54 
 Auditory organ, 109 
 Auditory sensations, 100 
 Auditory sensory processes, iii 
 Auditory space, 169 
 Axis cylinder, 39 
 Axone, 39 
 
 Barter, 252 
 
 Basilar membrane, 109 
 Beats, auditory, 112 
 Behavior, 5 
 
 animal, 248 
 
 and attitudes, 142 
 
 and belief, 266 
 
 and consciousness, 17 
 ■ and education, 343 
 
 and experience, 130 
 
 fundamental forms of, 23 
 
 of higher animals, 34 
 
 349 
 
350 
 
 PSYCHOLOGY 
 
 Behavior, higher forms of, 34, 68, 
 
 253 
 higher types of, and ideas, 304 
 
 ideational, 248 
 
 and imagination, 256 
 
 individual, 136 
 
 inherited, 138 
 \. and instincts, 199 
 
 ^"-v^ of multicellular animals, 22 
 ^^ nerve cells, 41 
 
 and organization, 313 
 
 organization of, 140 
 
 scientific studies of, 309 
 
 selective consciousness, 132 
 
 and sensitivity, 17 
 
 simplest types of, 16 
 
 speech, a form of, 209, 217 
 
 of unicellular animals, 1 6 
 
 voluntary, 301 
 
 and words, 235 
 Behaviorism, iii 
 Belief, 265 
 Berkeley, 179 
 Binocular vision, 180 
 Biological evolution, 334 
 Biology and psychology, 3 
 Blind spot, 9 
 
 Blind, the, tactual percepts of, 167 
 Brightness, ^^ 
 Broca, 56 
 Bryan, 338, 340 
 
 Cajal, 41, 44, 45, 49 
 Cameron, E. H., vii 
 Canals, semicircular, 107 
 Cause, idea of, and self, 275 
 Cells, gustatory, 120, 121 
 
 muscle, 134 
 
 nerve, 39 
 
 olfactory, 117, 118 
 Centers, in cerebrum, 50, 52, 53 
 
 higher, 29 
 
 nervous, 29 
 Central nerve cells, 22 
 Central nervous system, 25 
 Cerebellum, 28, 45 
 
 evolution of, 31 
 
 human, 38 
 Cerebral processes and choice, 305 
 Cerebrum, 28 
 
 cortex of, 50 
 
 evolution of, 31 
 
 human, 38, 47 
 
 Chemical senses, 123 
 Child psychology, 10 
 Child's idea of self, 270 
 Child's imagination, 259 
 Chinese writing, 221 
 Choice, simple, 304 
 
 voluntary, 68 
 Choroid coat of eye, 85, 87 
 Chromatic sensations, 74 
 Circulatory activities, 154 
 Circulatory movements, 1 54 
 Classification, of conscious proc- 
 esses, 61 
 
 threefold, 63 
 Cochlea, auditory, 108 
 Codfish, nervous system of, 31 
 Coherency, criterion of, 258 
 Cold spots, 122 
 Color, 74 
 Color blindness, 90 
 
 of periphery of retina, 89 
 
 table of, 99 
 Color circle, 76 
 Color-mixing, 92 
 
 table of, 100 
 Color names, 75 
 Colors, complementary, 93 
 Combinations of sensations, 163 
 Communication, animal, 213 
 
 systems of, 212 
 Complementary colors, 93 
 Concept of self, 269, 272 
 Concepts, 251 
 
 scientific, 262 
 
 validity of, 263 
 Concrete words, 235 
 Conduct, control of, 253 
 Cones of retina, 87, 88 
 Conflict of instincts, 200 
 Conn, 83 
 Consciousness, and behavior, 17 
 
 definition of, 12 
 
 and evolution, 3, 250 
 
 and heredity, 203 
 
 nervous conditions of, 5 
 
 and nervous structures, 38 
 
 and physical facts, 72 
 
 selective, 130 
 
 and sympathy, 160 
 Content, literary, 329 
 Contiguity, association by, 245 
 Contractile cells, 19 
 Contractility, 15 
 
INDEX 
 
 351 
 
 Contrast, association by, 246 
 
 of self and not-self, 27 1 
 
 space, 174 
 
 visual, 96 
 
 visual, table of, 100 
 Control, of behavior, 135 
 
 in mental hygiene, 315 
 Coordinating center, nervous sys- 
 tem as, 25 
 Coordination, 136 
 
 of activities, 314 
 Cord, human, 38, 42, 44 
 
 spinal, 28 
 Cornea of eye, Sy 
 Cortex, of cerebellum, 45 
 
 cerebral, 44, 49, 50 
 Corti, arch of, no 
 Creation theory of language, 210 
 Criticism, of ideas in hypnotism, 
 291 
 
 of imagination, 256 
 
 literary, 260 
 Crowbar Case, 58 
 Current, nervous, 21 
 Czermak, 104 
 
 Darwin, 202 
 
 Deafness, tone, 115 
 
 Decision, 306 
 
 Definition of psychology, 12 
 
 Delayed instincts, 198 
 
 Delirium, 287 
 
 Dendrites, 39 
 
 Depth, visual, 179, 186 
 
 Design in art, 324 , 
 
 Development, plateau in, 339 
 
 of self-consciousness, 269 
 
 of space, 165 
 Diagnosis, psychological, 337 
 Difference tones, 112 
 Differences, individual, 2 
 Diffusion, 203, 204, 206 
 
 nervous, 60 
 Digestion, 15 
 
 in higher forms, 19 
 Direct behavior, 248 
 Disappointment, 155 
 Discord, 114 
 
 Discrimination and words, 227 
 Diseases, toxic effects of, 286 
 Displeasure, 147 
 Dissociation, 278 
 
 degrees of, 281 
 
 Distance, of sounds, 171 
 
 visual, 178 
 Dog, nervous system of, 31 
 Dove, nervous system of, 31 
 Dreams, 283 
 Drugs, 279, 285 
 Dual personality, 292 
 
 in hypnosis, 291 
 
 Ear, evolution of, 103 
 
 structure of, 104 
 Ebbinghaus, 113 
 Economy of mental effort, 320 
 Edinger, 46, 47, 48 
 Education, 336 
 
 and choice, 309 
 Efficient cause and self, 275 
 Elements of consciousness, 73 
 Embryological methods of localiza- 
 tion, 53 
 Emotional expression and speech, 
 
 211 
 Emotional life, disturbance of, 299 
 Emotional reactions, 253 
 Emotions, 147 
 
 in experiments, 8 
 
 higher experiences, 153 
 Empirical tests of imagination, 257 
 Equilibration, organ of, 107 
 " Essay toward a New Theory of 
 
 Vision," 180 
 Ether, concept of, 258 
 Ethics, 346 
 Eustachian tube, 106 
 Evolution, and behavior, 133 
 
 of belief, 265 
 
 of complex organisms, 32 
 
 and consciousness, 3, 250 
 
 of ear, 103 
 
 of eye, 80 
 
 of gestures, 217 
 
 human, 333 
 
 of ideas, 253 
 
 of instincts, 198 
 
 of muscles, 134 
 
 of nervous system, 31 
 
 parallel of behavior and structure, 
 
 23 
 Excessive excitation^ 298 
 
 Excitation, process of, 21 
 
 Experience, and behavior, 130 
 
 definition of, 12 
 
 and emotions, 152 
 
352 
 
 PSYCHOLOGY 
 
 Experience, of lower animals, 27 
 
 ordinary, i 
 
 and physical facts, 2 
 
 and time, 191 
 Experiences, classifications of, 63 
 Experiment, auditory space, 170 
 
 in psychology, 7 
 Experimental psychology, 1 1 
 Experiments, on the present, 191 
 
 reaction, 310 
 Expression and mental life, 343 
 Extensor movements, 1 54 
 Extirpation, 51 
 
 as method of localization, 51 
 Eye, evolution of, 80 
 
 human, 84 
 
 Facilitation, principle of, 59 
 
 Familiarity, visual perception, 184 
 
 Fatigue, 280 
 
 Fatigued nerve cells, 280 
 
 Fear, 148, 149, 150, 201 
 
 Fechner, 129 
 
 Feeling, 63 
 
 and intuition, 329 
 
 organic, 153 
 Feelings, cultivated, 147 
 Fibers, in cerebrum, 47 
 
 nerve, 39 
 
 systems of, in cerebrum, 47 
 Figures : 
 
 Association fibers, 47 
 
 Association by similarity, 245 
 
 Balance, 158 
 
 Binocular parallax, 182 
 
 Blind spot, 9 
 
 Cerebellum, human, 45 
 
 Cerebral centers, 52, 53 
 
 Cerebral cortex, 49, 50 
 
 Cerebrum, human, 46 
 
 Chinese writing, 221 
 
 Cochlea, auditory, 109 
 
 Color circle, 76 
 
 Cord, human, 44 
 
 Corpus callosum, 48 
 
 Curve of sleep, 282 
 
 Development of telegraphic lan- 
 guage, 338, 340 
 
 Ear, 104 
 
 Evolution of eye, 82 
 
 Evolution of letter M, 222 
 
 Eye, human, 85 
 
 Fatigued nerve cells, 280 
 
 Human nervous system, 38 
 Involuntary movements during 
 
 attention, 157 
 Localization of functions, 52, 53 
 Movements of unicellular ani- 
 mals, 16 
 Miiller-Lyer illusion, 172 
 Muscle cell, 134 
 Muscle cells, primitive, 20 
 Muscular contraction, 135 
 Nasal cavity, 116 
 Nerve cells, 20, 39, 40 
 Nerve cells, evolution of, 41 
 Nervous system of alligator, 31 
 Nervous system of codfish, 31 
 Nervous system of dog, 31 
 Nervous system of dove, 31 
 Nervous system of frog, 28 
 Ojibwa love letter, 220 
 Olfactory cells, 117, 118 
 Peduncular fibers, 46 
 Photographs of eye movements, 
 
 177 
 Poggendorff illusion, 176 
 
 Relation of retinal image to size 
 
 of object, 179 
 Retina, 88 
 Sensory cells in vestibule of ear, 
 
 108 
 Sensory processes and reactions, 
 
 143 
 Sound waves in beats, 113 
 
 Space-contrast illusion^ 174 
 
 Spinal cord, human, 42, 44 
 
 Stag beetle, nervous system of, 25 
 
 Starfish and nervous system, 24 
 
 Structure of hydra, 18 
 
 Synapses, 40 
 
 Taste bulbs, 119, 120, 121 
 
 Touch organs, 124, 125, 126, 127 
 
 Wave forms, ^^ 
 
 Zollner illusion, 176 
 
 Figures of speech, 238 
 
 Fiske, John, 151, 152 
 
 Flechsig, 52 
 
 Flexor movements, 154 
 
 Food instincts, 198 
 
 Form, recognition of, 132 
 
 Fovea centralis^ 89 
 
 FrankHn, Mrs. C. L., 97 
 
 Freedom of will, 308 
 
 Frog, behavior of, 35 
 nervous system of, 28 
 
INDEX 
 
 353 
 
 Fusion, 64, 67, 70 
 of sensations, 163 
 and space, 187 
 and use, 190 
 
 Galton, 242 
 
 General ideas and words, 234 
 
 Generalization, 264 
 
 Geometrical perspective, 184 
 
 Gesture language, 216 
 
 GlandSi active organs, 138 
 
 Golgi-Mazzoni corpuscle, 125 
 
 Gossip, evolution of word, 231 
 
 Gravity, concept of, 232 
 
 Gray, sensations of, 74 
 
 Gray matter, nervous, 42 
 
 Greeff, 88 
 
 Greek column, 158 
 
 Greek philosophy and psychology, 2 
 
 Habit, 304 
 
 and consciousness, 207 
 
 and diffusion, 203 
 
 and instinct, 202 
 
 and perception, 191 
 Habits, 195 
 
 derived from instincts, 199 
 
 motor, 341 
 Hair, nerves around, 126 
 Haller, 18, 20 
 Hallucinations, 278 
 Handwriting, habit of, 204 
 Harmony, musical, 114 
 Harter, 338, 340 
 Heat spots, 123 
 Hebrew alphabet, 223 
 Helmholtz, no, in 
 Herrick, 108, 109 
 Higher animals, behavior of, 34 
 Hodge, 280 
 Hydra, 18 
 
 Hygiene, mental, 314 
 Hyperaesthesia in hypnosis, 290 
 Hypnosis, 279, 287, 288 
 
 Idea of self, 269 
 Ideas, 70 
 
 abstract, 263 
 
 balancing of, 306 
 
 characteristic of man, 239 
 
 dominant, 321 
 
 in dreams, 283 
 
 flexibility of, 247 
 
 general, 264 
 
 higher behavior, 304 
 
 and higher social life, 268 
 
 and impressions, 240, 241, 254 
 
 influence of, 249 
 
 and memory, 240 
 
 scientific, 258 
 
 and speech, 209, 215 
 
 verbal, 233 
 Ideation, 68 
 
 wholesome, 320 
 Ideational attitudes, 254 
 Ideational behavior, 248 
 Illusion of weights, 159 
 Illusions, 278 
 
 optical, 172 
 Imageless ideas, 232 
 Imageless thought, 246 
 Imagery, and ideas, 246 
 
 individual variations in, 242 
 
 and words, 232, 233 
 Images, and ideas, 237 
 
 memory, 6 
 
 as obstructions to thought, 238 
 Imagination, 251, 254 
 
 child's, 259 
 
 literary, 260, 330 
 
 personifying, 255 
 
 uncritical, 259 
 Imitation, and speech, 212 
 
 theory of speech, 210 
 Impressions, and ideas, 254 
 
 not ideas, 240 
 
 sensory, 66 
 Impulse, 302 
 Incus, 106 
 
 Indirect behavior, 219, 248 
 Indirect nervous centers, 30 
 Individual, higher, self-sufficiency 
 
 of, 33 
 
 Infant expression, 214 
 
 Infant recognition of space, 165 
 
 Inheritance of nervous structures, 
 
 26 
 Insanity, 279, 294, 296 
 Instinctive behavior, 301 
 Instinctive life, disturbance of, 299 
 Instincts, 26, 138, 196, 198, 207 
 
 and religion, 267 
 
 and sentiments, 267 
 Intensities, sensation, 126 
 Intensity of sounds, 102 
 Interest and behavior 132 
 
354 
 
 PSYCHOLOGY 
 
 Interjection theory of speech, 211 
 Intervening objects and visual 
 
 space, 185 
 Intoxication, 286 
 Introspection, 4, 13, 14, 311 
 
 and classification, 66 
 
 defects of, 6 
 
 sensations, 141 
 Introspective psychology, 331 
 Intuition and feeling, 329 
 Involuntary attention, 303 
 Irritability, 15 
 Irritable cells in higher forms, 19 
 
 James, William, vi, 342 
 Jastrow, 157 
 Jealousy, 152 
 Jennings, 16 
 Judgment, 264 
 
 Kipling, 149, 150, 151 
 Knowledge, 63 
 Kohlschiitter, 282 
 
 Language, 209 
 
 and ideas, 215, 322 
 Law, Weber's, 127 
 Learning curve, 338, 340 
 Learning handwriting, 205 
 Learning, units of, 320 
 Lens, evolution of, 83 
 
 of eye, 85 
 Letters, evolution of, 222 
 Libertarianism, 308 
 Life, concept of, 275 
 Light, analysis of, 3 
 
 external, 78 
 Literary content,, 329 
 Literary imagination, 260 
 Local signs, 168 
 
 Localization of brain functions, 50, 58 
 Location, auditory, 169 
 Locke, John, i 
 Locomotion, instinct of, 199 
 Loeb, 24 
 Logic, 265, 345 
 Lotze, 168 
 
 Loudness of sounds, 102 
 Love, parental, 151 
 
 M, letter, evolution of, 222 
 Mallery, 220 
 Malleus, 105 
 
 Meatus, external, 104 
 
 internal, 106 
 Mechanical laws and space, 187 
 Mechanical senses, 123 
 Medulla, 28 
 
 human, 38 
 Melancholia, 297 
 Memory, 14, 64, 67, 70, 196, 320 
 
 experiments in, 7 
 
 and ideas, 240 
 
 physiological conditions of, 32 
 
 training of, 243 
 
 and words, 226 
 Mental hygiene, 314 
 Metaphysics, 347 
 Method, indirect, in psychology, 14 
 
 in psychology, 4 
 Methods of brain localization, 50 
 Mind and evolution, 333 
 Missenian corpuscle, 124 
 Mixed colors, "]"] 
 Motive for psychology, i, 2 
 Motor area, cerebral, 55 
 Motor areas in cerebral cortex, 50, 
 
 52. 53 
 Motor nervous process, 22 
 
 Motor processes, 59, 64 
 
 in sleep, 284 
 Motor reactions, 311 
 Movements, analysis of, 311 
 
 and attitudes, 1 54 
 
 eye, 175, 176 
 
 in reactions, 312 
 
 undeveloped, 206 
 
 and visual perception, 186 
 Miiller-Lyer illusion, 172 
 Multicellular animals, 18 
 Multiple personality, 293 
 Muscle cell, 134 
 Muscle, sense organs in, 125 
 Muscles of eye, 84 
 Muscular tension, general, 302 
 Mythology, 259 
 
 Nagel, 52 
 Narcotics, 285 
 Nasal cavity, 116 
 Negative after-images, 95 
 Nerve cells, 39 
 
 evolution of, 41 
 
 fatigued, 280 
 
 types of, 22 
 Nervous centers, higher, 31 
 
INDEX 
 
 355 
 
 Nervous conditions, of conscious- 
 ness, 5 
 
 and drugs, 285 
 Nervous current, 21 
 Nervous processes and sensations, 7 2 
 Nervous structures and conscious- 
 ness, 38 
 Nervous system, as basis of psycho- 
 logical classification, 61 
 
 and behavior, 35 
 
 centralized, 23 
 
 of frog, 28 
 
 human, 38 
 
 stag beetle, 25 
 
 starfish, 24 
 
 vertebrate, 27 et seq. 
 Neurones, 39 
 
 evolution and development of, 41 
 Newton, Isaac, 3 
 Noise, 102 
 Number names, 228 
 Number terminology, 227 
 Numerals, systems of, 229 
 
 Objective, 13, 271 
 
 Objects and perception, 188 
 
 Observation, and classification, 61 
 
 in psychology, 8 
 
 self-, 4 
 Occult in psychology, 2 
 Ojibwa writing, 220 
 Olfactory lobes, 28 
 Olfactory organ, 116 
 Optic lobes, 28 
 Optical illusions, 172 
 Organ of Corti, 109, no, in 
 Organic activities, 315 
 Organic feelings, 153 
 Organic retentiveness, 195 
 Organic sensations, 125 
 Organization, 64 
 
 for behavior, 34 
 
 of behavior, 141 
 
 concept of, in psychology, 313 
 
 and decision, 306 
 
 and diffusion, 60 
 
 idea of, 275 
 
 of ideas, 254 
 
 normal consciousness, 287 
 
 principle of, 60 
 
 self-directed, 324 
 
 and thought, 320 
 Ossicles, chain of, 106 
 
 Overexcitation, 286 
 Overtones, 102 
 
 Pacinian corpuscles, 124 
 Pain, 62 
 Pain spots, 123 
 Parental love, 151 
 Paths, nervous, 26 
 
 nervous, in cord, 42 
 Peduncular fibers, 46 
 Perception, (^^^ 164, 174, 304 
 
 of objects, 188 
 
 summary of, 194 
 Percepts, of blind, 167 
 
 and habits, 191 
 
 and repetition, 190 
 Perceptual analysis, 316 
 Perceptual behavior, 248 
 Perceptual process, example of, 252 
 Perceptual synthesis, 317 
 Personality, disorganized, 278 
 
 dual, 292 
 
 dual, in hypnosis, 291 
 
 multiple, 293 
 
 scientific idea of, 274 
 
 and volition, 308 
 Personifying imagination, 255 
 Perspective, aerial, 184 
 
 geometrical, 184 
 Philosophy, 344 
 
 Photographic records of eye move- 
 ments, 175 
 Phrenology, 57 
 Physical facts, and consciousness, 
 
 72,79 
 and experience, 2 
 
 Physiological conditions, of con- 
 scious processes, 249 
 
 of experience, 14 
 
 of habit, 201 
 
 of sleep, 279 
 Physiological psychology, v, 1 1 
 Physiology, visual perception, 175 
 Pictographic writing, 219 
 Pigment-mixing, 94 
 Pinna of ear, 103 
 Pitch, loi 
 
 Plateau in learning, 339 
 Play, 137 
 Pleasure, 62, 146 
 Poggendorff, 176 
 Positive after-images, 95 
 Post-hypnotic effects, 295 
 
356 
 
 PSYCHOLOGY 
 
 Practice, effects on illusions, 173 
 
 and illusions, 177 
 Preface, first edition, v 
 
 second edition, iii 
 Present, the, 191 
 Pressure spots, 123 
 Prevision, 307 
 Primary colors, 75 
 Problem, meaning of term, 237 
 Protective instincts, 197 
 Protoplasm, 15 
 Psychiatry, 11, 299 
 Psychology, abnormal, 278 
 
 and aesthetics, 346 
 
 animal, 10 
 
 and its applications, 268, 325 
 
 and biology, 3 
 
 child, 10 
 
 definition of, 12 
 
 and ethics, 346 
 
 experimental, 8,11 
 
 forms of, 10, II 
 
 functional, v , 
 
 Greek, 2 
 
 and logic, 345 
 
 and metaphysics, 347 
 
 and philosophy, 344 
 
 and physics, 3 
 
 physiological, v, 5, 11 
 
 scope of, 12, 69, 70 
 
 social, II 
 
 structural, v 
 
 subdivisions of, 10 
 Psycho-physics, 73 
 Purple, 76 
 Purpose and choice, 309 
 
 Quality, tonal, 10 1 
 
 Reaction experiments, 310 
 Reaction times, 310 
 Reactions, 66 
 
 motor, 311 
 
 sensory, 311 
 Reading of blind, 167 
 Reasoning, 264 
 Rebus and alphabet, 223 
 Recall and memory, 244 
 Recency and memory, 243 
 Recognition and attention, 161 
 Reflex, 44 
 
 Relativity of temperature sense, 123 
 Religion and self-consciousness, 273 
 
 Religious belief, 267 
 Reproduction, 15 
 
 evolution of, 33 
 
 in higher forms, 19 
 Retention and memory, 244 
 Retentiveness, organic, 195 
 Retina, 87 
 
 Retinal image, size of, 178 
 Retinal rivalry, 183 
 Retzius, 126, 127 
 Rhythm, prose, 327 
 
 and time, 193 
 Rivalry, retinal, 183 
 Rods of retina, 87, 88 
 Rolando, fissure of, 53 
 Roman numerals, 229 
 Ruffini, 125 
 
 Saturation, color, 77 
 Scala, tympani, 109 
 
 vestibuli, 109 
 Science, development of, 261 
 Scientific ideas, 258 
 Scientific studies of learning, 342 
 Self, idea of, 269 
 
 as scientific concept, 272 
 
 unity of, 275 
 Self-consciousness, 273 
 
 development of, 269 
 Self-directed organization, 324 
 Self-observation, 4, 13 
 Semicircular canals, 107 
 Sensation intensities, 126 
 Sensations, 66, 69, 71 
 
 auditory, loi 
 
 combination and arrangement of, 
 162 
 
 introspective, 141 
 
 muscle, 125 
 
 organic, 125 
 
 of smell, 117 
 
 of taste, 119 
 
 of touch, 121 
 
 visual, 74 
 Sense organ and visual sensations, 
 
 80 
 Senses, chemical and mechanical, 
 
 123 
 Sensitive cells, 19 
 Sensitivity, 17 
 Sensory area, cerebral, 55 
 Sensory areas in cerebral cortex, 
 50' 52, 53 -:C 
 
INDEX 
 
 357 
 
 Sensory cells, 20 
 Sensory centers, 29 
 Sensory impressions, 34 
 
 meaning of, 139 
 Sensory nervous centers, 29 
 Sensory processes, 22, 64 
 Sensory reactions, 311 
 Sentiments, 267 
 Shadows, 185 
 Shame, 152 
 
 Sheath of Schwann, 39 
 Signs, local, 168 
 Similarity, association by, 245 
 Size, perception of, 175 
 
 visual, 178 
 Sleep, 279, 281 
 
 curve, 282 
 
 and motor processes, 284 
 Smell, 116 
 
 rudimentary sense, 118 
 Smith, C. H., vii 
 
 Social consciousness and self, 272 
 Social influence and thought of in- 
 dividual, 225 
 Social life and higher mental proc- 
 esses, 267 
 Social motives and language, 223 
 Social psychology, 1 1 
 Social sciences, 208, 331 
 Sociology, 335 
 Solidity, visual, 181 
 Sound, localization of, 171 
 
 physical, loi 
 Sounds and communication, 213 
 Space, auditory, 169 
 
 many senses, 169 
 
 and movement, 187 
 
 product of fusion, 163 
 
 tactual, 164 
 
 visual, 172 
 Specialization, 318 
 
 of functions, 18 
 Spectrum, 76 
 Speech, 209 
 
 and ideas, 215 
 
 origin of, 210 
 wSpeech center in cerebrum, 56 
 Speech centers, 54 
 Spencer, 335 
 Spinal cord, frog's, 28 
 Stapes, 106 
 
 Starfish, nervous system of, 24 
 Stereoscope, 181 
 
 Stimulation, 21 
 
 as method of localization, 51 
 Stimuli, gustatory, 121 
 
 olfactory, 118 
 Stimulus, 20 
 
 physical, 127 
 Structural psychology, v 
 Subdivisions of psychology, 10 
 Subjective, 13, 271 
 Suggestions, 289, 291 
 Summation tones, 113 
 Sylvian fissure, 54 
 Symbolic value, 252 
 Symbols, number, 228 
 
 writing, 221 
 Sympathy, 158 
 
 and consciousness, 160 
 Synapses, 40, 41 
 
 in sleep, 280 
 Synthesis, perceptual, 317 
 
 Tables : 
 
 After-images, 100 
 
 Auditory processes, 115 
 
 Color blindness, 99 
 
 Color contrasts, 100 
 
 Color-mixing, 100 
 
 Experiences, 37 
 
 Forms of behavior, 36, 37 
 
 Nervous structures, 36, 37 
 
 Physical light and sensations, 79 
 
 Red-green color blindness, 91 
 Tallies, 228 
 
 and number, 228 
 Taste, sensations of, 116, 119 
 Taste bulbs, 119 
 Taylor, I., 222 
 Telegraphic language, 338 
 Temperature, production of, in ani- 
 mals, 32 
 Temperature spots, 122 
 Tension, constant, in muscles, 
 
 138 
 
 experiments on, 156 
 Tensor tympani, 105 
 Tests of imagination, 256 
 Testute, 39, 124 
 Theories, of color vision, 97 
 
 of origin of language, 211 
 Thought relations, 234 
 Timbre, 102 
 Time, 191 
 Tone deafness, 115 
 
358 
 
 PSYCHOLOGY 
 
 Tones, difference, 112 
 
 summation, 113 
 Tool-consciousness, 249 
 Tooth, nerve in, 127 
 Touch, inner, 168 
 
 organs of, 122 
 
 sensations, 121 
 
 space, 164 
 Toxic substances, 286 
 Tracts, nervous, 59 
 Trench, 230 
 Tschermak, 52 
 Tympanic membrane, 105 
 
 Uncritical imagination in dreams, 284 
 Unicellular animals, 15 
 
 behavior of, 16 
 Unity, concept of, 276 
 
 of objects, 189 
 
 of self, 275 
 
 Value, ideas of, 252 
 Verbalism, 266, 322 
 Verse, 328 
 
 and time, 192 
 Vesicle, auditory, 103 
 Vestibule, auditory, 107 
 Vibrations, light, 78 
 
 sound, loi 
 Vision, adaptation of, to behavior, 132 
 
 and touch, 166 
 
 Visual area in cerebrum, 52, 53, 54 
 Visual space, 172 
 Visualize^rs, 242 
 Vitreous humor, 85 
 Vividness, 62 
 
 and memory, 243 
 Volition, 63, 7c, 301 
 
 and attitudes, 319 
 Voluntary choice, 68 
 
 Walking as instinct, 199 
 Wave forms, 77 
 Weber, 127, 164 
 Weber's Law, 127 
 
 interpretations of, 128 
 White, sensations of, 74 
 Will, 63 
 
 freedom of, 308 
 Wonder, motive for psychology, i 
 Words, abstract, 236 
 
 evolution of, 230 
 
 experiments, 226 
 
 and general ideas, 234 
 
 interpretation of, 6 
 
 recognition of, 318 
 
 social values of, 224 
 Work song and language, 218 
 Writing, evolution of, 219 
 Wundt, Wilhelm, vi, 167 
 
 Zollner, 176 
 
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