THE Principles OF PSYCHOLOGY BY WILLIAM JAMES TBOFBBSOR OF P8TCHOLOGT IN'HARYABD UNiyERfilTT CONTENTS. CHAPTER XVII. Sensation, 1 Its distinction from perception, 1. Its cognitive function— acquaintance with qualities, 8. No pure sensations after ttie first days of life, 7. The * relativity of knowledge,' 9. The law of contrast, 18. The psychological and the physiological theories of it, 17. Bering's experiments, 20. The * eccentric projection ' of sensations, 81. CHAPTER XVIII. Imagination, 44 Our images are usually vague. 45. Vague images not neces- sarily general notions, 48. Individuals differ in imagination; Galton's researches, 50 The 'visile* tjrpe, 68. The 'audile' type, 60. The ' motile ' type, 61. Tactile images. 65. The neural process of imagination, 68. Its relations to that of sensation, 72. CHAPTER XIX. The Perception OF 'Things/ . -n- . . . 76 Perception and sensation. 76. Perception is of definite and probable things, 82. Illusiona. 85 ;— of the first type, 86 ;— of the second type, 95. The neural process in perception, 108. 'Apperception,' 107. Is perception an unconscious inference? 111. Hallucinations, 114. The neural process in hallucination, 122. Binet's theory, 129. * Perception -time,' 181. CHAPTER XX. The Perception of Space, 134 The feeling of crude extensity, 134. Tiie perception of spatial order, 145. Space-' relations,' 148. The nienning of lo(;AlizHtion, 158. 'Local signs.' 155. The construction of ' real ' 8i)ace, 166. The subdivision of the original sense-spaces, 167. The sensation iU IV CONTENTS, PAOB of motion over surfaces, 171. The measurement of the sense- spaces by each other, 177. Their summation, 181. Feelings of movement in joints, 189. Feelings of muscular contraction, 197. Summary so far, 202. How the blind perceive space, 203. Visual space, 211. Uelmholtz and Reid on the test of a sensation, 216. The theory of identical points, 222. The theory of projection, 22b. Ambiguity of retinal impressions, 231 ; — of eye- movements, 284 The choice of the visual reality, 237. Sensations which we ignore, 240. Sensations which seem suppressed, 243. Dis- cussion of Wundt's and Helmholtz's reasons for denying that retinal sensations are of extension, 248. Summary, 268. His- torical remarks, 270. CHAPTER XXI. The Perception of Reality, 283 Belief and its opposites, 283. The v arious orders of reality, 287. * Practical' realities, 293. The sense of our own bodily existen^:^ the nucleus of all reality, 297. The paramount reality of sensations, 299. The influence of emotion and active impulse on belief, 307. Belief in theories, 311. Doubt, 318. Relations of belief and will, 320. CHAPTER XXII. Reasoning, 323 ' Recepts,' 327. In reasoning, we pick out essential qualities, 329. What is meant by a mode of conceiving, 332. What is involved in the existence of general proposition8| 337. The two factore jif reasoning, 340. Sagacity, 343. The part played by association by similarity. 845. The intellectual contrast between brute and man : association by similarity the fundamental human distinction, 348. Different orders of human genius, 360. CHAPTER XXIII. The Production of Movement, 373 The diffusive wave, 373. Every sensation produces reflex effects on the whole organism, 874. CHAPTER XXIV. Instinct, . 383 Its definition. 383 Instincts not always blind or invariable. 389. Two principles of non -uniformity in instincts: 1) Their inhibition by habits, 394 ; 2) Their transitoriness, 398. Man has CONTENTS. more InstiDcts than any other mammal, 408. Reflex impulses, 404.^mitation, 408. Emulation, 409. Pugnacity, 409. Sym- patl^ 410. The hunting in9tinct, 411. Fear, 415. Acquisitive- ne», 422. Constructiveness, 426. Play, 427. Curiosity, 429. Sociability and shyness, 480. Secretiveness, 482. Cleanliness, 484. Shame, 485. Love, 487. Maternal love, 489. CHAPTER XXV. The Emotions, 442 Instinctive .xfiaction and emotional expression shade imper- ceptibly into each other, 442. The expression of grief, 448 ; of fear, 446 ; of hatred, 449. Emotion J8 a consequence, not the cause, of the bodily expression, 449. Difficulty of testing this view, 454. Olijections to it discussed, 456. The subtler emotions, 468. No special brain-centres for emotion, 472. Emotional dif- ferences between individuals, 474. The genesis of the various emotions, 477. CHAPTER XXVI. Will, 486 Voluntary movements : they presuppose a memory of invol- untary movements. 487. Kinsesthetic impressions, 488. No need to assume feelings of innervation, 503. The * mental cue ' for a movement may be an image of its visual or auditory effects as well as an image of the way it feels, 518. Ideo motor action, 522. Action after deliberation, 528. Five types of decision, 531. The feeling of effort, 535. Unheal thiness of will: 1) The ex- plosive type. 537 ; 2) The obstructed type, 546. Pleasure and pain are not the only springs of action, 549. All consciousness is impulsive, 551. What wo will depends on what idea dominates in our mind, 559. The idea's outward elTecls follow from the cerebral machinery, 560. Effort of intention to a naturally repugnant idea is the essential foalure of willing, 562. The free-will controversy. 571. P.sychology, as ii science, ran safely postulate delerniinism, even if free-will be true, 076. The edu- cation of the Will, 579. Hypothetical brain-schemes, 582. CHAPTER XXVII. ' - Hypnotism, 594-616 Modes of operating and susceptibility, 594. Theories about the hypnotic state, 596. The symptoms of the trance, 601. Tl 00NTENT8. CHAPTER XXVIII. PAGK Neobssaby Tbuths and the Effects of Experience, . 617 Programme of the chapter, 617. Elementary feelings are innate, 618. The question refers to their combinations, 619. What is meant by 'experience/ 620. Spencer on ancestral ex- perience, 620. Two ways in which new cerebral structure arises : the * back-door ' and the * front-door * way, 625. The genesis of the elementary mental categories, 681. The genesis of the natural sciences, 688. Scientific conceptions arise as accidental variations, 686. The genesis of the pure sciences, 641. Series of evenly increasing terms, 644. The principle of mediate compari- son, 645. That of skipped intermediaries, 646. Classification, 646. Predication, 647. Formal logic, 648. Mathematical propositions, 652. Arithmetic, 658. Geometry, 656. Our doc- trine is the same as Locke's, 661. Relations of ideas v. couplings of things. 668. The natural sciences are inward ideal schemes with which the order of nature proves congruent, 666. Meta- physical principles are properly only postulates, 669. JSsthetic and moral principles are quite incongruent with the order of nature, 672. Summary of what precedes, 675. The origin of instincts, 678. Insufficiency of proof for the transmission to the next generation of acquired habits, 681. Weismann's views, 688. Conclusion, 688. PSYCHOLOGY. CHAPTEB XVn. SENSATION. Afteb inner perception, outer perception I The next three chapters will treat of the processes by which we cog- nize at all times the present world of space and the mate- rial things which it contains. And first, of the process called Sensation. SIQS'SATION AND TJSSBXJBSPTIOJSI DISTINGTJISHBD. The toords Sensation and Perception do not carry very definitely discriminated meanings in popular speech, and in Psychology also their meanings run into each other. Both of them name processes in which we cognize an objective world; both (under normal conditions) need the stimula- tion of incoming nerves ere they can occur ; Perception always involves SeDsation as a portion of itself ; and Sensa- tion in turn never takes place in adult life without Percep- tion also being there. They are therefore names for dif- ferent cognitive functions, not for different sorts of mental fact. The nearer the object cognized comes to being a simple quality like * hot,' ' cold,' * red,' * noise,' * pain,' ap- prehended irrelatively to other things, the more the state of mind approaches pure sensation. The fuller of relations the object is, on the contrary ; the more it is something classed, located, measured, compared, assigned to a func- tion, etc., etc.; the more unreservedly do we call the state of mind a perception, and the relatively smaller is the part in it which sensation plays. Sensation, then, so long as ice take the ancdylic point of 2 PBTGHOLOGT. vieWf differs from Perception only in the extreme simplicity of its object or content* Its function is that of mere acquaintance with a fact. Perception's function, on the other hand, is knowledge abovt f a fact ; and this knowledge admits of numberless degrees of complication. But in both sensa- tion and perception we perceive the fact as an immediately present outioard reality ^ and this makes them diflfer from * thought ' and * conception,' whose objects do not appear present in this immediate physical way. From the physio^ * Some persons will say that we never have a really simple object or content. My definition of sensation does not require the simplicity to be absolutely, but only relatively, extreme. It is worth while in passing, however, to warn the reader against a couple of inferences that are often made. One is that because we gradually learn to analyze so many quali- ties we ought to conclude that there are no really indecomposable feelings in the mind. The other is that because the processes that produce our sen- sations are multiple, the sensations regarded as subjective facts must also be compound. To take an example, to a child the taste of lemonade comes at first as a simple quality. He later learns both that many stimuli and many nerves are involved in the exhibition of this taste to his mind, and he also learns to perceive se^ftirately the sourness, the coolness, the sweet, the lemon aroma, etc. , and the several degrees of strength of each and all of these things, — ^the experience falling into a large number of aspects, each of which is abstracted, classed, named, etc., and all of which appear to be the elementary sensations into which the original ' lemonade flavor ' is decomposed. It is argued from this that the latter never was tne simple thing which it seemed. I have already criticised this sort of reasoning in Chapter YI (see pp. 170 ff.). The mind of the child enjoying the simple lemonade flavor and that of the same child grown up and analyzing it are in two entirely different conditions. Subjectively considered, the two states of mind are two altogether distinct sorts of fact. The later mental state says ^ this is the same fla^xyr {or fluid) which that earlier state per- ceived as simple/ but that does not make the two states themselves identical. It is nothing but a case of learning more and more about the same topics of discourse or things.— Many of these topics, however, must be confessed to resist all analysis, the various colors for example. He who sees blue and yellow * in ' a certain green means merely that when green is oonfrouted with these other colors he sees relations of similarity. He who sees abstract ' color ' in it means merely that he sees a similarity between it and all the other objects known as colors. (Similarity itself cannot ultimately be ac- counted for by an identical abstract element buried in all the similars, as has been already shown, p. 492 ff.) He who sees abstract paleness, inten- sity, purity, in the green mean's other similarities still. These are all out- ward determinations of that special green, knowledges a6(W^ it, zufdUige An-^ sichten, as Herbart would say. not elements of its composition. Compare the article by Meinong in the Yierteljahrachrif t f Or wiss. Phil. . xu. 324. t See above, p. 221. SENSATION. 3 logical point of view both sensations and perceptions differ from * thoughts ' (in the narrower sense of the word) in the fact that nerve-currents coming in from the periphery are involved in their prodvction. In perception these nerve-currents arouse vdumi- nous associative or reproductive processes in the cortex; but when sensation occurs alone, or with a minimum of perception, the ac- companying reproductive processes are at a minimum too. I shall in this chapter discuss some general questions more especially relative to Sensation. In a later chapter perception will take its turn. I shall entirely pass by the classification and natural history of our special 'sensa- tions,' such matters finding their proper place, and being sufficiently well treated, in all the physiological books.* THE COGNinVlS VJTNCTION OF SUNSATION. A pure sensation is an abstraction; and when we adults talk of our * sensations ' we mean one of two things : either certain objects, namely simple qualities or attributes like hard, hot, pain; or else those of our thoughts in which acquaintance with these objects is least combined with knowledge about the relations of them to other things. As we can only think or talk about the relations of objects with which we have acquaintance already, we are forced to postulate a function in our thought whereby we first become aware of the bare immediate natures by which our several objects are distinguished. This function is sensation. And just as logicians always point out the distinction between substantive terms of discourse and relations found to obtain between them, so psychologists, as a rule, are ready to admit this function, of the vision of the terms or matters meant, as something distinct from the knowledge about them and of their relations inter se. Thought with the former function is sensational, with the latter, intellec- tuaL Our earliest thoughts are almost exclusively sensa- tionaL They merely give us a set of thuts, or its, of subjects * Those who wish a fuller treatment than Martin's Human Body affords may be recommended to Bernstein's ' Five Senses of Man/ in the Interna- tional Scientific Series, or to Ladd's or Wundt's Physiological Psychology. Hie completeat compendium is L. Hermann's Handbuch der Physiologies fol. ra. 4 PaTCHOLOQT, of discourse, with their relations not brought out The first time we see lighty in Condillac's phrase we are it rather rather than see it But all our later optical knowledge is about what this experience gives. And though we were struck blind from that first moment, our scholarship in the subject would lack no essential feature so long as our mem- ory remained. In training-institutions for the blind they teach the pupils as much about light as in ordinary schools Beflection, refraction, the spectrum, the ether-theory, etc., are all studied. But the best taught born-blind pupil of such an establishment yet lacks a knowledge which the least instructed seeing baby has. They can never show him what light is in its * first intention ' ; and the loss of that sensible knowledge no book-learning can replace. All this is so obvious that we usually find sensation * postulated ' as an element of experience, even by those philosophers who are least inclined to make much of its importance, or to pay respect to the knowledge which it brings.* ♦ ** The sensations which ^e postulate as the signs or occasions of our perceptions" (A. Seth: Scottish Philosophy, p. 89). "Their existence is mippased only because, without them, it would be impossible to account for the complex phenomena which are directly present in consciousness " (J. Dewey: Psychology, p. 84). Even as great an enemy of Sensation as T. H. Green has to allow it a sort of hypothetical existence under protest. *• Perception presupposes feeling " (Coutemp. Review, vol. xxxi. p. 747). Cf. also such passages as those in his Prolegomena to Ethics, §§ 48, 49. — Physiologically, the sensory and the reproductive or associative processes may wax and wane independently of each other. Where the part directly due to stimulation of the sense-organ preponderates, the thought has a sensational character, and differs from other thoughts in the sensational direction. Those thoughts which lie farthest in that direction we call sen- sations, for practical convenience, just as we call conceptiom those which lie nearer the opposite extreme. But we no more have conceptions pure than we have pure sensations. Our most rarefied intellectual states involve some bodily sensibility, just as our dullest feelings have some intellectual scope. Common -sense and common psychology express this by sjiyiug that the mental state is com|)osed of distinct fractional parts, one of which is sensation, the other conception. We, however, who believe ^very mental state to be an integral thing (p. 276) cannot talk thus, but must speak of the degree of sensational or intellectual character, or function, oL the mental state. Professor Hering puts, as usual, his finger better upon the truth than anyone else. Writing of visual perception, he says: ''It is inadmissible in the present state of our knowledge to assert that first and last the same retinal picture arouses exactly the sam^ pure sensation. SENSATION. 5 But the trouble is that most, if not all, of those who admit it, admit it as a fractional paH of the thought, in the old-fashioned atomistic sense which we have so often criti- cised. Take the pain called toothache for example. Again and again we feel it and greet it as the same real item in the universe. We must therefore, it is supposed, have a distinct pocket for it in our mind into which it and nothing else will fit This pocket, when filled, is the sensation of toothache ; and must be either filled or half-filled whenever and under whatever form toothache is present to our thought, and whether much or little of the rest of the mind be filled at the same time. Thereupon of course comes up the paradox and mystery : If the knowledge of toothache be pent up in this separate mental pocket, how can it be known cum alio or brought into one view with anything else ? This pocket knows nothing else ; no other part of the mind knows toothache. The knowing of tooth- ache cum alio must be a miracle. And the miracle must have an Agent And the Agent must be a Subject or Ego * out of time,' — and all the rest of it, as we saw in Chapter X. And then begins the well-worn round of recrimination between the sensationalists and the spiritualists, from which we are saved by our determination from the outset to accept the psychological point of view, and to admit knowledge whether of simple toothaches or of philosophic systems as an ultimate fact. There are realities and there are • states of mind,' and the latter know the former ; and it is just as wonderful for a state of mind to be a * sensation ' and know a simple pain as for it to be a thought and know a system but that this sensation, in consequence of practice and experience, is differ- ently interpreted the last time, and elaborated into a different perception from the first. For the only real daUi are, on the one hand, the physical picture on the retina, — and that is both times the same: and, on the other band, the resultant state of consciousness {ausgeloste Ernpfindungscamplex) — and that is both times distinct. Of any third thing, namely, a pure sen- sation thrust between the retinal and the mental pictures, we know nothing. We can then, if we wish to avoid all hypothesis, only say that the nervous appa- ratus reacts upon the same stimulus differently the last time from the first, and that in consequence the consciousness is different too. " (Hermann's Hdbcb., ni. I. 567-8.) 6 PBTCHOLOQT. of related things.* But there is no reason to suppose that when different states of mind know different things about the same toothache, they do so by virtue of their all con- taining faintly or vividly the original pain. Quite the re- verse. The by-gone sensation of my gout was painful, as Beid somewhere says ; the tJiovght of the same gout as by- gone is pleasant, and in no respect resembles the earlier mental state. Sensations, then, first make us acquainted with innu- merable things, and then are replaced by thoughts which know the same things in altogether other ways. And Locke's main doctrine remains eternally true, however hazy some of his language may have been, that ''though there be a great number of considerations wherein things may be compared one with another, and so a multitnde of relations ; yet they all terminate in, and are concerned about, those simple ideas f either of sensation or reflection, which I think to be the whole materials of all our knowledge. . . . The simple ideas we receive from sensation and reflection are the boundaries of our thoughts ; beyond which, the mind whatever efforts it would make, is not able to advance one jot ; nor can it make any discoveries when it would pry into the nature and hidden causes of those ideas." t The nature and hidden causes of ideas will never be unravelled till the nexus between the brain and conscious- ness is cleared up. All we can say now is that sensations oxejirat things in the way of consciousness. Before con- ceptions can come, sensations must have come ; but before sensations come, no psychic fact need have existed, a nerve- current is enough. If the nerve-current be not given, nothing else will take its place. To quote the good Locke again: **It is not in the power of the most exalted wit or enlarged under- standing, by any quickness or variety of thoughts, to invent or frame * Yet even writers like Prof. Bain will deny, in the most gratuitous way, that sensations know anything. "It is evident that the lowest or most restricted form of sensation does not contain an element of knowl- edge. The mere state of mind called the sensation of scarlet is not knowl- edge, although a necessary preparation for it. " ' Is not knowledge about scarlet * is all that Professor Bain can rightfully say. t By simple ideas of sensation Locke merely means sensations. ^ Essay c. H. U.. bk. n. ch. xxiii. § 29 ; ch. xxv. § 9. 8EN8ATI0K 7 one new simple idea [i.e. sensation] in the mind. ... I would have any one try to fancy any taste which had never affected his palate, or frame the idea of a scent he had never smelt ; and when he can do this, I will also conclude that a blind man hath ideas of colors, and a deaf man true distinct notions of sounds. ^^ * The brain is so made that all currents in it run one way. Consciousness of some sort goes with all the currents, but it is only when new currents are entering that it has the sensational tang. And it is only then that consciousness directly encounters (to use a word of Mr. Bradley's) a real- ity outside itself. The difference between such encounter and aU concep- tual knowledge is very great. A blind man may know all abotU the sky's blueness, and I may know all aboiU your toothache, conceptually ; tracing their causes from primeval chaos, and their consequences to the crack of doom. But so long as he has not felt the blueness, nor I the toothache, our knowledge, wide as it is, of these realities, will be hollow and inadequate. Somebody must fed blueness, somebody must have toothache, to make human knowledge of these matters real. Conceptual systems which neither began nor left off in sensations would be like bridges without piers. Systems about fact must plunge themselves into sensation as bridges pluuge their piers into the rock. Sensations are the stable rock, the terminus a quo and the terminus ad quern of thought To find such termini is our aim with all our theories — to conceive first when and where a certain sensa- tion may be had, and then to have it. Finding it stops dis- cussion. Failure to find it kills the false conceit of knowledge. Only when you deduce a possible sensation for me from your theorj*^, and give it to me w^hen and where the theory requires, do I begin to be sure that your thought has anything to do with truth. Pure sensations can only he realized in the earliest days of life. They are all but impossible to adults with memories and stores of associations acquired. Prior to all impressions on sense-organs the brain is plunged in deep sleep and con- sciousness is practically non-existent. Even the first weeks ♦ Op, cii. bk. II. ch. ii. § 2. 8 P8T0H0L0QT. after birth are passed in almost unbroken sleep bj human infants. It takes a strong message from the sense-organs to break this slumber. In a new-bom brain this gives rise to an absolutely pure sensation. But the experience leaves its ' unimaginable touch ' on the matter of the convolutions, and the next impression which a sense-organ transmits produces a cerebral reaction in which the awakened vestige of the last impression plays its part. Another sort of feel- ing and a higher grade of cognition are the consequence ; and the complication goes on increasing tiU the end of life, no two successive impressions falling on r^ identical brain, and no two successive thoughts being exactly the same. (See above, p. 230 ff.) The first sensation which an infant gets is for him the Uni- verse. And the Universe which he later comes to know is nothing but an amplification and an implication of that first simple germ which, by accretion on the one hand and in- tussusception on the other, has grown so big and complex and articulate that its first estate is unrememberable. In his dumb awakening to the consciousness of something there, a mere this as yet (or something for which even the term this would perhaps be too discriminative, and the intellec- tual acknowledgment of which would be better expressed by the bare interjection ' lo ! '), the infant encounters an ob- ject in which (though it be given in a pure sensation) all the ' categories of the understanding' are contained. It has objectivity y unity, svbstantiolUy, causality y in the fuU sense in which any later object or system of objects Jias these things. Here the young knower meets and greets his world ; and the miracle of knowledge bursts forth, as Voltaire says, as much in the infant's lowest sensation as in the highest achievemeDt of a Newton's brain. The physiological con- dition of this first sensible experience is probably nerve- currents coming in from many peripheral organs at once. Later, the one confused Fact which these currents cause to appear is perceived to be many facts, and to contain many qualities.* For as the currents vary, and the brain-paths * *• So far is it from being true that we necessarily have as many feel- ings in consciousness at one time as there are inlets to the sense then played upon, that it is a fundamental law of pure sensation that each momentary SENSATION. 9 Are moulded by them, other thoughts with other ' objects ' me, and the ' same thing ' which was apprehended as a present this soon figures as a past thaty about which many unsuspected things have come to light. The principles of this development have been laid down already in Chapters Xn and XIII, and nothing more need here be added to that account "THE BEIiATIVITY OF KNOWUBDGB." To the reader who is tired of so much Erkenrdnisstheoric I can only say that I am so myself, but that it is indispen- sable, in the actual state of opinions about Sensation, to try to clear up just what the word means. Locke's pupils seek to do the impossible with sensations, and against them we must once again insist that sensations ' clustered together ' <;annot build up our more intellectual states of mind. Plato's earlier pupils used to admit Sensation's existence, grudgingly, but they trampled it in the dust as something corporeal, non-cognitive, and vile.* His latest followers «tate of the organism yields but one feeling, however numerous may be its parts and its exposures. ... To this original Unity of consciousness it makes no difference that the tributaries to the siugle feeling are beyond the organ, ism instead of within it, in an outside object with several sensible proper- ties, instead of in the living body with its several sensitive functions. . . . The unity therefore is not made by ' association ' of several components; but the plurality is formed by dissociation of unsuspected varieties within the unity ; the substantive thing being no product of synthesis, but the residuum of differentiation." (J. Martineau : A Study of Religion (1888), p. 192-4.) Compare also F. H. Bradley, Logic, book i. chap. ii. * Such passages as the following abound in an ti -sensationalist literature: *• Sense is a kind of dull, confused, and stupid perception obtruded upon the soul from without, whereby it perceives the alterations and motions within its own body, and takes cognizance of individual bodies existing round about it, but does not clearly comprehend what they are nor pene- tmte into the nature of them, it bcinj^ intended by nature, as Plotinus speaks, iioi so properly for knowledge as for the use of the body. For the soul suf- fering under that which it perceives by way of passion cannot master or Conquer it, that is to say, know or understand it. For so Anaxagoras in Aris- taile very fitly expresses the nature of knowledge and intellection under ilie notion of Conquering. Wherefore it is necessary, since the mind under- stands all things, that it should be free from mixture and passion, for this end, as Anaxagoras speaks, that it may be able to master and conquer its objects, that is to say, to know and understand them. In like manner Plo- tinus, in his book of Sense and Memory, makes to suffer and to be conquered all one, as also to know and to conquer; for which reason he concludes thai 10 PSTCHOLOQT, seem to seek to crowd it out of existence altogether. The only reals for the neo-Hegelian writers appear to be rda-- tumsj relations without terms, or whose terms are only speciously such and really consist in knots, or gnarls of relations finer still in infinitum. ** Exclude from what we have considered real all qualities consti- tuted by relation, we find that none are left." *' Abstract the many relations from the one thing and there is nothing. . . . Without the relations it would not exist at all." * **The single feeling is nothing that which suffers doth not know. . . . Sense that suffers from external objects lies as it were prostrate under them, and is overcome by them. . . . Sense therefore is a certain kind of drowsy and somnolent percep- tion of that passive part of the soul which is as it were asleep in the body, and acts concretely with it. . . . It is an energy arising from the body and a certain kind of drowsy or sleeping life of the soul blended together with it. The perceptions of which compound, or of the soul as it were half asleep and half awake, are confused, indistinct, turbid, and encumbered cogitations very different from the energies of the noetical part, . . . which are free, clear, serene, satisfactory, and awakened cogitations. That isto* say, knowledges." Etc., etc., etc. (R. Cudworth: Treatise concerning Eternal and Immutable Morality, bk iii. chap, ii.) Similarly Male- branche: ' * ThIjodork. — Oh, oh, Ariste! God knows pain, pleasure, warmth, and the rest. But he does not feel these things. He knows pain, since he knows what that modification of the soul is in which pain consists. He knows it because he alone causes it in us (as I shall presently prove), and he knows what he does. In a word, he knows it because his knowledge has no bounds. But he does not feel it. Tor if so he would be unhappy. To know pain, then, is not to feel it. Ariste. — That is true. But to feel it is to know it, is it not ? Theodore.— No indeed, since God does not feel it in the least, and yet he knows it perfectly. But in order not to quibble about terms, if you will have it that to feel pain is to know it, agree at least that it is not to know it clearly, that it is not to know it by light and by evidence— in a word, that it is not to know its nature; in other words and to speak exactly, it is not to know it at all. To feel pain, for example, is ta feel ourselves unhappy without well knowing either what we are or what is this modality of our being which makes us unhappy. . . . Impose silence on your senses, your imagination, and your passions, and you will hear the pure voice of inner truth, the clear and evident replies of our common mas- ter. Never confound the evidence which results from the comparison of ideas with the liveliness of the sensations which touch and thrill you. The livelier our sensations and feelings (sentiments) are, the more darkness do they shed. The more terrible or agreeable are our phantoms, and the more body and reality they appear to have, the more dangerous are they and fit to lead us astray." (Entretiens sur la Metaphysique, 8me Entretien, od init.) Malebranche's Theodore prudently does not try to explain how God's ' infinite felicity ' Is compatible with his not feeling joy. ♦ Green: Prolegomena, §§ 20, 28. SENSATION, 11 real'' '* On the recognition of relations as constituting the nature of Vleas, rests the possibility of any tenable theory of their reality/' Such quotations as these from the late T. H. Green* would be matters of curiosity rather than of importance, were it not that sensationalist writers themselves believe in a so-called * Relativity of Blnowledge,' which, if they only understood it, they would see to be identical with Professor Green's doctrine. They tell us that the relation of sensa- tions to each other is something belonging to their essence, and that no one of them has an absolute content : "That, e.g., black can only be felt in contrast to white, or at least in distinction from a paler or a deeper black; similarly a tone or a sound only in alternation with others or with silence; and in like manner a smell, a taste, a touch, only, so to speak, in statu nascendi, whilst, when the stimulus continues, all sensation disappears. This all seems at first sight to be splendidly consistent both with itself and with the facts. But looked at more closely, it is seen that neither is the case." t ♦ Introd. to Hume, §§ 146, 188. It is hard to tell just what this aposto- lic human being but strenuously feeble writer means by relation. Some- times it seems to stand for system of related fact. The ubiquity of the ' psychologist's fallacy ' (see p. 196) in his pages, his incessant leaning on the confusion between the thing known, the thought that knows it, audthe farther things known about that thing and about that thought by later and additional thoughts, make it impossible to clear up his meaning. Compare, however, with the utterances in the text such others as these: ** The wak- ing of Self-consciousness from the sleep of sense is an absolute new begin- ning, and nothing can come within the ' crystal sphere ' of intelligence except as it is determined by intelligence. What sense is to sense is noth- ing for thought. What sense is to thought, it is as determined by thought. There can, therefore, be no 'reality' in sensjition to which the world of thought can be referre lying in shadow]. * Snch a mistake as this is undoubtedly of psychological origin. It is a wrong daasification of the appearances, due to the arousal of intricate processes of association, amongst which is the suggestion of a different hue from that really before the eyes. In the ensuing chapters such illusions as this will be treated of in considerable detail. But it is a mistake to luterpret the simpler cases of con- trast in the light of such illusions as these. These illu- sions can be rectified in an instant, and we then wonder how they could have been. They come from insufficient attention, or from the fact that the impression which we get is a sign of more than one possible object, and can be interpreted id either way. In none of these points do they resemble simple color-contrast, which unqueatioruMy is a phenomenon of sensation immediately aroused. 1 have dwelt upon the facts of color-contrast at such great length because they form so good a text to comment on in my struggle against the view that sensations are im- mutable psychic things which coexist with higher mental functions. Both sensationalists and intellectualists agree that such sensations exist. They /w^e, say the pure sen- sationalists, and make the higher mental function ; they are combined by activity of the Thinking Principle, say the intellectualists. I myself have contended that they do not exist in or alongside of the higher mental function when that exists. The things which arouse them exist ; and the higher mental function also knows these sj^me things. But just as its knowledge of the things supersedes and displaces, their knowledge, so it supersedes and displaces them,, when it comes, being as much as they are a direct result- ant of whatever momentary brain-conditions may obtain. The psychological theory of contrast, on the other hand> holds the sensations still to exist in themselves unchanged before the mind, whilst the * relating activity' of the latter * Mr. Delabarre's coDtrihulion ends here. 28 P8TCH0L00T, deals with them freely and settles to its own satisfaction what each shall be, in view of what the others also are. Wundt says expressly that the Law of Relativity is " not a law of sensation but a law of Apperception ;" and the word Apperception connotes with him a higher intellectual spon- taneity.* This way of taking things belongs with the phi- losophy that looks at the data of sense as something earth- bom and servile, and the * relating of them together ' as something spiritual and free. Lo! the spirit can even change the intrinsic quality of the sensible facts themselves if by so doing it can relate them better to each other ! But (apart from the difficulty of seeing how changing the sen- sations should relate them better) is it not manifest that the relations are part of the * content' of consciousness, part of the 'object,' just as much as the sensations are? Why ascribe the former exclusively to the knotver and the latter to the hwion ? The knotoer is in every case a unique pulse of thought corresponding to a unique reaction of the brain upon its conditions. AH that the facts of contrast show us is that the same real thing may give us quite diflferent sensations when the conditions alter, and tnat we must therefore be careful which one to select as the thing's truest representative. There are many other facts beside the phenomena of contrast which prove that when two objects act together on vs the sensation which either tvovld give alone becomes a different sensation, A certain amount of skin dipped in hot water gives the perception of a certain heat. More skin immersed makes the heat much more intense, although of course the water's heat is the same. A certain extent as well as in- tensity, in the quantity of the stimulus is requisite for any quality to be felt. Fick and Wunderli could not distin- guish heat from touch when both were applied through a ♦ Physiol. Psych., i. 851, 458-60. The full inanity of the law of rela- tivity is best to be seen in Wundt's treatment, where the great * allgemeiner Qetetz del' Beziehung,* invoked lo account for Weber's law as well as for the phenomena of contrast and many other matters, can only be defined as a tendency to feel all things in relation I/O each other I Bless its little soul I But why does it change the things so, when it thus feels them in relatioo? SEmATION. 29 bole in a card, and so confined to a small part of the skin. Similarly there is a chromatic minimum of size in objects. The image they cast on the retina must needs have a cer- tain extent, or it will give no sensation of color at all. In- versely, more intensity in the outward impression may make the subjective object more extensive. This happens, as will be shown in Chapter XIX, when the illumination is increased : The whole room expands and dwindles ac- cording as we raise or lower the gas-jei It is not easy to explain any of these results as illusions of judgment due to the inference of a wrong objective cause for the sen- sation which we get No more is this easy in the case of Weber's observation that a thaler laid on the skin of the forehead feels heavier when cold than when warm ; or of Szabadfoldi's observation that small wooden disks when heated to 122° Fahrenheit often feel heavier than those which are larger but not thus warmed;* or of Hall's ob- servation that a heavy point moving over the skin seems to go faster than a lighter one moving at the same rate of speed, t Bleuler and Lehmann some years ago called attention to a strange idiosyncrasy found in some persons, and con- sisting in the fact that impressions on the eye, skin, etc., were accompanied by distinct sensations of sound.X Colored hearing is the name sometimes given to the phenomenon, which has now been repeatedly described. Quite lately the Viennese aurist Urbantschitsch has proved that these cases are only extreme examples of a very general law, and that all our sense-organs influence each other's 8ensations.§ The hue of patches of color so distant as not to be recog- nized was immediately, in U.'s patients, perceived when a tuning-fork was sounded close to the ear. Sometimes, on the contrary, the field was darkened by the souud. The acuity cf vision was increased, so that letters too far off to be read could be read when the tuning-fork was heard. Urbantschitsch, varying his experiments, found that their ♦ Ladd : Physiol. Psych., p. 848. t Mind, X. 567. X Zwangsmassige LichtempfinduDg durch Schall (Leipzig, 1881). % PflUger's Archiv, xi-n. 1.54. 80 PaTCHOLOQT. results were mntual, and that sounds which were on the limits of audibility became audible when lights of various colors were exhibited to the eye. Smell, taste, touch, sense of temperature, etc., were all found to fluctuate when lights were seen and sounds were heard. Individuals varied much in the degree and kind of effect produced, but almost every one experimented on seems to have been in some way affected. The phenomena remind one somewhat of the * dynamogenic ' effects of sensations upon the strength of muscular contraction observed by M. Fer^, and later to be described. The most familiar examples of them seem to be the increase of pain by noise or light, and the increase of nausea by all concomitant sensations. Persons suffering in any way instinctively seek stillness and darkness. Probably every one will agree that the best way of for- mulating all such facts is physiological : it must be that the cerebral process of the first sensation is reinforced or other- wise altered by the other current which comes in. No one, surely, will prefer a psychological explanation here. Well, it seems to me that all cases of mental reaction to a plural- ity of stimuli must be like these cases, and that the phy- siological formulation is everywhere the simplest and the best. When simultaneous red and green light make us see yellow, when three notes of the scale make us hear a chord, it is not because the sensations of red and of green and of each of the three notes enter the mind as such, and there * combine ' or * are combined by its relating activity ' into the yellow and the chord, it is because the larger sum of light-waves and of air-waves arouses new cortical processes, to which the yellow and the chord directly correspond. Even when the sensible qualities of things enter into the objects of our highest thinking, it is surely the same. Their several sensations do not continue to exist there tucked away. They are replaced by the higher thought which, although a different psychic unit from them, knows the same sensible qualities which they know. The principles laid down in Chapter VI seem then to be corroborated in this new connection. You cannot build up one thought or one sensation out of many: and only direct 8EN8ATI0K 81 tooperimefnt can inform us of what ive ahaU perceive when we get many stimuli at once, THE ' BCCSirTBIC FBO JECTION ' OF SENSATIONS. We often hear the opinion expressed that all our sensa- tions at first appear to us as subjective or internal, and are afterwards and by a special act on our part ' extradited ' or 'projected' so as to appear located in an outer world. Thus we read in Professor Ladd's valuable work that '* Sensations ... are psychical states whose place-^so far as they can be said to have one— t^f the mind. The transference of these sensations from mere mental states to physical processes located in the periphery of the body, or to qualities of things projected in space external to the body, is a mental act. It may rather be said to be a mental ochieveTnent (cf. Cud worth, above, as to knowledge being conquering], for it is an act which in its perfection results from a long and intricate process of de- velopment. . . . Two noteworthy stages, or * epoch-making' achieve- ments in the process of elaborating the presentations of sense, require a special consideration. These are * localization,^ or the transference of the composite sensations from mere states of the mind to processes or conditions recognized as taking place at more or less definitely fixed points or areas of the body; and ' eccentric projection'' (sometimes called 'eccentric perception') or the giving to these sensations an objective existence (in the fullest sense of the word ' objective ') as qualities of objects situated within a field of space and in contact with, or more or less reraotely distant from, the body.'' * It seems to me that there is not a vestige of evidence for this \'iew. It hangs together with the opiuion that our sen- sations are originally devoid of all spatial content, t an opinion which I confess that I am wholly at a loss to under- stand. As I look at my bookshelf opposite I cannot frame to myself an idea, however imaginary, of any feeling which I could ever possibly have got from it except the feeling of * Physiological Psychology, 385, 387. See also such passsges as that in Bain ; The Seuses and the Intellect, pp. 364-6. f * • Especially must we avoid all attempts, whether avowed or concealed, to account for the spatial qualities of the presentations of sense by merely describing the qualities of the simple sensations and the modes of their combmation. It is position and extension in space which constitutes the very peculiarity of the objects as no longer mere sensations or affections of the mind. As sensations, they are neither out of ourselves nor possessed of the qualities indicated by the word spread-out." (Ladd. op. eit. p. 391.) 32 PaTCHOLOQT. the same big extended sort of outward fact whicli I now perceive. So far is it from being true that our first way of feeling things is the feeling of them as subjective or men- tal, that the exact opposite seems rather to be the truth. Our earliest, most instinctive, least developed kind of con- sciousness is the objective kind ; and only as reflection be- comes developed do we become aware of an inner world at all. Then indeed we enrich it more and more, even to the point of becoming idealists, with the spoils of the outer world which at first was the only world we knew. But subjective consciousness, aware of itself as subjective, does not at first exist Even an attack of pain is surely felt at first objectively as something in space which prompts to motor reaction, and to the very end it is located, not in the mind, but in some bodily part. ** A Bensation which should not awaken an impulse to move, nor any tendency to produce an outward effect, would manifestly be use- less to a living creature. On the principles of evolution such a sensa- tion could never be developed. Therefore every sensation originally refers to something external and independent of the sentient creature. Rhizopods (according to Engeimann's observations) retract their pseudo- podia whenever these touch foreign bodies, even if these foreign bodies are the pseudopodia of other individuals of their own species, whilst the mutual contact of their own pseudopodia is followed by no such contraction. These low animals can therefore already feel an outer world — even in the absence of innate ideas of causality, and probably without any clear consciousness of space. In truth the conviction that something exists outside of ourselves does not come from thought. It comes from sensation; it rests on the same ground as our conviction of our own existence. ... If we consider the behavior of new-bom animals, wo never find them betraying that they are first of all con- scious of their sensations as purely subjective excitements. We far more readily incline to explain the astonishing certainty with which they make use of their sensations (and which is an effect of adaptation and inheritance) as the result of an inborn intuition of the outer world. . . . In8::3ad of starting from an original pure subjectivity of sensa- tion, and seeking how this could possibly have acquired an objectii . signification, womust. on the contrary, begin by the possession of objec tivity by the sensation and then show how for reflective consciousness the latter becomes interpreted as an effect of the object, how in short the original immediate objectivity becomes changed into a remote one."* * A. Riehl: Der Philosopbischer Kriticismus, Bd. n. Theil ii. p. 64. 8EN8ATI0N. 33 Another confusion, much more common than the denial of all objective character to sensations, is the assumption that they are all originally located inside the body and are pro- jected outward by a secondary act. This secondary judg- ment is always false, according to M. Taine, so far as the place of the sensation itself goes. But it happens to hit a real object which is at the point towards which the sensation is projected ; so we may call its result, according to this author, a veridical hallucination,* The word Sensation, to * On Intelligence, part u. bk. ii. chap. n. §§ vn, vni. Compare such statements as these : " The consequence is that when a sensation has for its usual condition the presence of an object more or less distant from our bodies, and experience has once made us acquainted with this distance, we shall situate our sensation at this distance.— This, in fact, is the case with sensations of hearing and sight. The peripheral extremity of the acoustic nerve is in the deep-seated chamber of the ear. That of the optic nerve is in the most inner recess of the eye. But still, in our present state, we never situate our sensations of sound or color in these places, but without us, and often at a considerable distance from us. . . . All our sensations of color are thus projected out of our body, and clothe more or less distant objects, furniture, walls, houses, trees, the sky, and the rest. This is why, when we afterwards reflect on them, we cease to at- tribute them to ourselves; they are alienated and detached from us, so far as to appear different from us. Projected from the nervous surface in which we localize the majority of the others, the tie which connected them to the others and to ourselves is undone. . . . Thus all our sensa- tions are wrongly situated, and the red color is no more extended on the arm chair than the sensation of tingling is situated at my fingers' ends. TLey are all situated in the sensory centres of the encephalon; all appear situated elsewhere, and a common law allots to each of them its apparent situation." (Vol. n. pp. 47-68.) — Similarly Schopenhauer: "I will now show the same by the sense of sight. The immediate datum is here limited to the sens*ition of the retina which, it is true, admits of con- siderable diversity, but at bottom reverts to the impression of light and dark with their shades, and that of colors. Ihis sensjition is through and through subjective, that is, inside of the organism and under the skin." (Schopenhauer: Salz vom Grunde, p. 58.) This philoso- pher then enumerates seriatim what the Intellect does to make the origi- nally subjective sensation objective: 1) it turns it bottom side up; 2) it I educes its doubleness to singleness; 8) it changes its flatness to solidity; and i) it projects it to a distance from the eye. Again: '* 8ensatw7is are what we call the impressions on our senses, in so far as they come to our consciousness as states of our own body, especially of our nervous apparatus; we call them perceptiotis when we form out of them the repre- sentation of outer objects." (Helmholtz: Tonempfindungen, 1870, p. 101.) — Once more : " Sensation is always accomplished in the psychic centres, but it manifests itself at the excited part of the periphery, in other words. 84 P8YCH0L0QY. begin with, is constantly, in psychological literature, used as if it meant one and the same thing with the physical im- pression either in the terminal organs or in the centres, which is its antecedent condition, and this notwithstanding that by sensation we mean a mental, not a physical, fact But those who expressly mean by it a mental fact still leave to it a physical place, still think of it as pbjectively inhabiting the very neural tracts which occasion its appear- ance when they are excited ; and then (going a step farther) they think that it must place itself where they place it, or be subjectively sensible of that place as its habitat in the first instance, and afterwards have to be moved so as to appear elsewhere. All this seems highly confused and unintelligible. Con* sciousness, as we saw in an earlier chapter (p. 214) canno« properly be said to inhabit any place. It has dynamic re- lations with the brain, and cognitive relations with every- thing and anything. From the one point of view we may say that a sensation is in the same place with the brain (if we like), just as from the other point of view we may say that it is in the same place with whatever quality it may be cognizing. But the supposition that a sensation primi- tively /f?eZ5 either itself or its object to be in the same place imth the brain is absolutely groundless, and neither a priori probability nor facts from experience can be adduced to show that such a deliverance forms any part of the original cognitive function of our sensibility. Where, then, do we feel the objects of our original sensa- tions to be ? Certainly a child newly born in Boston, who gets a sen- sation from the candle-flame which lights the bedroom, or from his diaper-pin, does not feel either of these objects to one is conscious of the phenomenon in the nervous centres, . . . but one perceives it in the peripheric organs. This phenomenon depends on the experience of the sensations themselves, in which there is a nflection of the subjective phenomenon and a tendency on the part of perception to return as it were to the external cause which has roused the mental state because the latter is connected with the former." (Sergi : Psychologie Physiologi(iue (Paris, 1888), p. 189 )- The clearest and best passage I know is in Liebmuun: Der Objective Anblick (1869), pp. 67-72, but it is unfortu- nately too long to quote. SENSATION. 86 be situated in longitude 72° W. and latitude 41*" N. He does not feel them to be in the third story of the house. He does not even feel them in any distinct manner to be to the right or the left of any of the other sensations which he may be getting from other objects in the room at the same time. He does not, in short, know anything about their space-relations to anything else in the world. The flame fills its own place, the pain fills its own place ; but as yet these places are neither identified with, nor discriminated from, any other places. That comes later. For the places thus first sensibly known are elements of the child's space- world which remain with him all his life ; and by memory and later experience he learns a vast number of things about those places which at first he did not know. But to the end of time certain places of the world remain defined for him as the places where those sensations were ; and his only possible answer to the question where anything is will be to say * ihere^ and to name some sensation or other like those first ones, which shall identify the spot Space meanjs but the aggregate of all our possible sensations. There is no duplicate space known aliunde, or created by an ' epoch- making achievement ' into which our sensations, originally spaceless, are dropped. They bring space and all its places to our intellect, and do not derive it thence. By his body, then, the child later means simply that place where the pain from the pin, and a lot of other sensations like it. were or are felt. It is no more true to say that he locates that pain in his body, than to say that he locates his body in that pain Both are true : that pain is part of what he means by the word body. Just so by the outer world the child means nothing more than that place where the candle- flame and a lot of other sensations like it are felt. He no more locates the candle in the outer world than he locates the outer world in the candle. Once apjain, he does both ; for the candle is part of what he means by ' outer world.' This (it seems to me) will be admitted, and will (I trust) be made still more plausible in the chapter on the Percep- tion of Space. But the later developments of this percep- tion are so complicated that these simple principles get 86 P8TCH0L0Q7, easily overlooked. One of the complications comes from the fact that things movey and that the original object which we feel them to be splits into two parts, one of which re- mains as their whereabouts and the other goes off as their quality or nature. We then contrast where they tvere with where they are. If toe do not move, the sensation of where they tvere remains unchanged ; but we ourselves presently move, so that that also changes ; and * where they were ' becomes no longer the actual sensation which it was origi- nally, but a sensation which we merely conceive as possible. Gradually the system of these possible sensations, takes more and more the place of the actual sensations. ' Up ' and * down ' become ' subjective ' notions ; east and west grow more * correct ' than * right * and ' left ' etc.; and things get at last more * truly * located by their relation to certain ideal fixed co-ordinates than by their relation either to our bodies or to those objects by which their place was originally defined. Now this revision of our original locali- zaiions is a complex affair; and contains some /acts which may very naturally come to be described as translocations whereby sensations get shoved farther off than they originally appeared. Few things indeed are more striking than the change- able distance which the objects of many of our sensations may be made to assume. A fly's humming may be taken for a distant steam-whistle ; or the fly itself, seen out of focus, may for a moment give us the illusion of a distant bird. The same things seem much nearer or much farther, according as we look at them through one end or another of an opera-glass. Our whole optical education indeed is largely taken up with assigning their proper distances to the objects of our retinal sensations. An infant will grasp at the moon ; later, it is said, he projects that sensation to a dis- tance which he knows to be beyond his reach. In the much quoted case of the * 3'oung gentleman who was bom blind,' and who was 'couched' for the cataract by Mr. Chesselden, it is reported of the patient that " when he first saw, he was so far from making any judgment about dis- tances, that he thought all objects whatever touched his eyes (as he expressed it) as what he felt did his skin." And other patients born blind, but relieved by surgical op- SENSATION. 39 eration, have been described as bringing their hand close to their eyes to feel for the objects which they at first saw, and only gradually stretching out their hand when they found that no contact occurred. Many have concluded from these facts that our earliest visual objects must seem in immediate contact with our eyes. But tactile objects also may be affected with a like am- biguity of situation. If one of the hairs of our head be pulled, we are pretty accurately sensible of the direction of the pulling by the movements imparted to the head.* But the feeling of the pull is localized, not in that part of the hair's length which the fingers hold, but in the scalp itself. This seems con- nected with the fact that our hair hardly serves at all as a tactile organ. In creatures with vibrissce, however, and in those quadrupeds whose whiskers are tactile organs, it can hardly be doubted that the feeling is projected out of the root into the shaft of the hair itself. We ourselves have an approach to this when the beard as a whole, or the hair as a whole, is touched. We perceive the contact at some dis- tance from the skin. When fixed and hard appendages of the body, like the teeth and nails, are touched, we feel the contact where it objectively is, and not deeper in, where the nerve-termina- tions lie. If, however, the tooth is loose, we feel two contacts, spatially separated, one at its root, one at its top. From this case to that of a hard body not organically connected with the surface, but only accidentally in contact with it, the transition is immediate. With the point of a cane we can trace letters in the air or on a wall just as with the finger-tip ; and in so doing feel the size and shape of the path described by the cane's tip just as immediately as, \^'ithout a cane, we should feel the path described by the tip of our finger. Similarly the draughtsman's immediate perception seems to be of the point of his pencil, the sur- ♦ Tbls Is proved by Weber's device of causing the head to be firmly pressed against a support by another person, whereupon the direction of traction ceases to be perceived. 38 PSTCHOLOOy, geon's of the en^ of his knife, the duellist's of the tip of hift rapier as it plunges through his enemy's skin. When on the middle of a vibrating ladder, we feel not only our feet on the round, but the ladder's feet against the ground far below« If we shake a locked iron gate we feel the middle^ on which our hands rest, move, but we equally feel the sta- bility of the ends where the hinges and the lock are, and we seem to feel all three at once.* And yet the place where the contact is received is in all these cases the skin, whose sensations accordingly are sometimes interpreted a» objects on the surface, and at other times as objects a long distance off. We shall learn in the chapter on Space that our^eelinga of our own movement are principally due to the sensibility of our rotating joints. Sometimes by fixing the attention, say on our elbow-joint, we can feel the movement in the joint itself; but we always are simultaneously conscious of the path which during the movement our finger-tipa describe through the air, and yet these same finger-tips- themselves are in no way physically modified by the motion. A blow on our ulnar nerve behind the elbow is felt both there and in the fingers. Refrigeration of the elbow pro- duces pain in the fingers. Electric currents passed through nerve-trunks, whether of cutaneous or of more special sen- sibility (such as the optic nerve), give rise to sensations which are vaguely localized beyond the nerve-tracts traversed. Persons whose legs or arms have been ampu- tated are, as is well known, apt to preserve an illusory feeling of the lost hand or foot being there. Even when they do not have this feeling constantly, it may be occa- sionally brought back. This sometimes is the result of exciting electrically the nerve- trunks buried in the stump '* I recently faradized," says Dr. Mitchell, ** a case of disarticulated shoulder without warning my patient of the possible result. 1 'or two years he had altogether ceased to feel the limb. As the current affected the brachial plexus of nerves he suddenly cried aloud, * Oh the liand,— the hand ! ' and attempted to seize the missing member. The pliantom * Lotze: Med. Psych.. 428-433; Lipps: Grundtatsachen dts Seelenle bens, 582. SENSATION, 39 I had conjnred up swiftly disappeared, but no spirit could haye more amazed the man, so real did it seem/' * * * Now the apparent position of the lost extremity varies. Often the foot seems on the ground, or follows the position of the artificial foot, where one is used. Sometimes where the arm is lost the elbow will seem bent, and the hand in a fixed position on the breast Sometimes, again, the position is non-natural, and the hand will seem to bud straight out of the shoulder, or the foot to be on the same level with the knee of the remaining leg. Sometimes, again, the position is vague; and sometimes it is ambiguous, as in another patient of Dr. Weir Mitchell's who **lo8t his leg at the age of eleven, and remembers that the foot by degrees approached, and at last reached the knee. When he began to wear an artificial leg it reassumed in time its old position, and he is never at present aware of tha leg as shortened, unless for some time he talks and thinks of the stump, and of the missing leg, when . . . the direction of attention to the part causes a feeling of discomfort, and the subjective sensation of active and unpleasant movement of the toes. With these feelings returns at once the delusion of the foot as being placed at the knee/' All these facts, and others like them, can easily be de- scribed as if our sensations might be induced by circum- stances to migrate from their original locality near the brain or near the surface of the body, and to appear farther off ; and (under different circumstances) to return again after having migrated. But a little analysis of what happens shows us that this description is inaccurate. The objectivity tvith which each of our sensations originally comes to us, the roomy and, spatial character tvhich is a primi- tive part of its content ^ is not in the first instance relative to any other sensalion. The first time we open our eyes we get an optical object which is a place, but which is not yet placed in relation to any other object, nor identified with any place otherwise known. It is a place with which so far we are only ocquainted. When later we know that this same place is in * front * of us, that only means that we have learned Something about it, namely, that it is congruent tvith that ♦ lDJur?es to Nerves (Philadelphia. 1872), p. 360 ff. 40 PBYCHOLOOT. other place, called 'front,' which is given us by certain sen-, sations of the arm and hand or of the head and body. But at the first moment of our optical experience, even though we already had an acquaintance with our head, hand, and body, we could not possibly know anything about their relations to this new seen object. It could not be immedi- ately located in respect of them. How its place agrees with the places which their feelings yield is a matter of which only later experience can inform us; and in the next chapter we shall see with some detail how later experience does this by means of discrimination, association, selection, and other constantly working functions of the mind. When, therefore, the baby grasps at the moon, that does not mean that what he sees fails to give him the sensation which he afterwards knows as distance ; it means only that he has not learned at what tactile or iminval distance things which ap- pear at that visual distance are.* And when a person just operated for cataract gropes close to his face for far-off objects, that only means the same thing. All the ordinary optical signs of differing distances are absent from the poor creature's sensation anyhow. His vision is monoerular (only one eye being operated at a time); the lens is gone, and everything is out of focus; he feels photophobia, lachry- mation, and other painful resident sensations of the eyeball itself, whose place he has long since learned to know in tactile terms ; what wonder, then, that the first tactile reac- tion which the new sensations provoke should be one associated with the tactile situation of the organ itself? And as for his assertions about the matter, what wonder, again, if, as Prof. Paul Janet says, they are still expressed in the tactile language which is the only one he knows. " To be tovehed. means for him to receive an impression with- out first making a movement." His eye gets such an impression now ; so he can only say that the objects are 'touching it.* ** All his language, borrowed from touch, but applied to the objects of his sight, make us think that he perceives differently from ourselves, ♦ In reality it probably means only a restless movement of desire, which he might make even after he had become aware of his impotence to touch the object. SEN8ATI0N. 41 whereas, at bottom, it is only his different way of talking about the same experience."* The other cases of translocation of onr sensations are equally easily interpreted without supposing any 'projec- tion * from a centre at which they are originally perceived. Unfortunately the details are intricate ; and what I say now can only be made fully clear when we come to the next chapter. We shall then see that we are constantly select- ing certain of our sensations as realities and degrading others to the status of signs of these. When we get one of the signs we think of the reality signified ; and the strange thing is that then the reality (which need not be itself a sensation at all at the time, but only an idea) is so interest- ing that it acquires an hallucinatory strength, which may even eclipse that of the relatively uninteresting sign and en- tirely divert our attention from the latter. Thus the sen- sations to which our joints give rise when they rotate are signs of what, through a large number of other sensations, tactile and optical, we have come to know as the movement of the whole limb. This movement of the whole limb is what we think of when the joint's nerves are excited in that way ; and its place is so much more important than the joint's place that our sense of the latter is taken up, so to speak, into our perception of the former, and the sensation of the movement seems to diflfuse itself into our very fingers and toes. But by abstracting our attention from the sug- gestion of the entire extremity we can perfectly well per- ceive the same sensation as if it were concentrated in one spot. We can identify it with a differently located tactile and visual image of *the joint' itself. Just so when we feel the tip of our cane against the ground. The peculiar sort of movement of the hand (im- possible in one direction, but free in every other) which we experience when the tip touches ' the ground,' is a sign to us of the visual and tactile object which we already * Revue Philosopbique, vii. p. 1 fif., an admirable critical article, in the course of which M. Janet gives a bibliography of the cases in question. See also Dunan: tbid. xxv. 165-7. They are also discussed »nd similarly interpreted by T. K. Abbot : Sight and Touch (1864), chapter x. 42 P8TOH0L0OY. know under that name. We think of ^ the ground ' as being there and giving us the sensation of this kind of movement The sensation, we say, comes/rom the ground. The ground's place seems to be its place; although at the same time, and for very similar practical reasons^ we think of another optical and tactile object, ' the hand ' namely, and consider that its place cdao must be the place of our sensation. In other words, we take an object or sensible content A, and confounding it with another object otherwise known, B, or with two objects otherwise known, B and C, we identify its place with their places. But in all this there is no ^project- ing ' (such as the extradition-philosophers talk of) of A out of an original place; no primitive location which it first occupied, away from these other sensations, has to be con- tradicted ; no natural * centre,* from which it is expelled, exists. That would imply that A aboriginally came to us in definite local relations with other sensations, for to be ovi of B and C is to be in local relation with them as much as to be twthem is so. But it was no more out of B and O than it was in them when it first came to us. It simply had nothing to do with them. To say that we feel a sen- sation's seat to be * in the brain ' or * against the eye ' or * under the skin * is to say as much about it and to deal with it in as non-primitive a way as to say that it is a mile off. These are all secondary perceptions, ways of defining the sensation's seat per aliud. They involve numberless associations, identifications, and imaginations, and admit a great deal of vacillation and uncertainty in the result.* I conclude y then, that there is no truth in the * eccentric pro- jection' theory. It is due to the confused assumption that the bodily processes which cause a sensation must also be its seat f But sensations have no seat in this sense. They * The intermediary aud shortened locations of the lost hand and foot in the amputation cases also show this. It is easy to see why the phantom foot might continue to follow the position of the artificial one. But I confeae that I cannot explain its half way-positions. f It is from this confused assumption that the time-honored riddle comes, of how, with an upside-down picture on the retina, we can see things right-side up. Our consciousness is naively supposed to inhabit the 8EN8ATI0K 43 heoome seats for each other, as fast as experience associates them together; but that violates no primitive seat possessed by any one of them. And though our sensations cannot then so analyze and talk of themselves, yet at their very first appearance quite as much as at any later date are they cognizant of all those qualities which we end by extracting and conceiving under the names of objectivity , eocteriority^ and extent. It is surely subjectivity and interiority which are the notions latest acquired by the human mind. * picture and to feel the picture's position as related to other objects of space. But the truth is that the picture is non-existent either as a habitat or as any- thing else, for inunediate consciousness. Our notion of it is an enormous- ly late conception. The outer object is given immediately with all those qualities which later are named and determined in relation to other sensa- tions. The * bottom * of this object is where we see what by touch we afterwards know as out feet, the ' top * is the place in which we see what we know as other people's heads, etc., etc. Berkeley long ago made this matter perfectly clear (see his Essay towards a new Theory of Vision, §§9»-98, 118-118). * For full justification the reader must see the next chapter. He may object, against the summary account given now, that in a babe's immediate field of vision the various things which appear arc located relatively to each other from the outset. I admit that if discriminated, they would appear so located. But they are parts of the content of one sensation, not sensations separately experienced, such as the text is concerned with. The fully de- veloped ' world/ in which all our sensations ultimately find location, is nothing but an imaginary object framed after the pattern of the field of vision, by the addition and continuation of one sensation upon another in an orderly and systematic way. In corroboration of my text I must refer to pp. 57-dO of Riehl's book quoted above on page 82, and to Uphues: Wahmehmung und Empfindung (1888), especially the Einleitung and pp. 51-61. CHAPTER XVnX IMAGINATION. Sensations, once experienced, modify the nervous organism^ ' %o thai copies of them arise again in the mind after the orig- inal outxjoard stimvlris is gone. No mental copy, however, can arise in the mind, of any kind of sensation which has never been directly excited from without. The blind may dream of sights, the deaf of sounds, for years after they have lost their vision or hearing ; * but the man horn deaf can never be made to imagine what sound is like, nor can the man horn blind ever have a mental vision. In Locke's words, already quoted, " the mind can frame unto itself no one new simple idea." The originals of them all must have been given from without. Fantasy, or Imagination, are the names given to the faculty of repro- ducing copies of originals once felt. The imagination is called * reproductive ' when the copies are literal ; * pro- ductive ' when elements from diflferent originals are recom- bined so as to make new wholes. After-images belong to sensation rather than to imagi- nation ; so that the most immediate phenomena of imagi- nation would seem to be those tardier images (due to what the Germans call Sinnesgeddchtniss) which were spoken of in Vol. I, p. 647, — coercive hauntings of the mind by echoes of unusual experiences for hours after the latter have taken place. The phenomena ordinarily ascribed to imagination, however, are those mental pictures of possible sensible ♦ Prof. Jaslrow has ascertained by statistical inquiry among the blind that if their blindness have occurred before a period embraced between the fifth and seventh years the visual centres seem to decay, and visual dreams and images are gradually outgrown. If sight is lost after the seventh year, visual imagination seems to survive through life. See Prof. J.*s in- teresting article on the Dreams of the Blind, in the New Princeton Review for January 1888. 44 IMAGINATION. 45 experiences, to which the ordinary processes of associa- tive thought give rise. When represented with surroundings concrete enough to constitute a date, these pictures, when they revive, form recollections. We have already studied the machinery of recollection in Chapter XVI. When the mental pictures are of data freely combined, and reproducing no past com- bination exactly, we have acts of imagination properly so called. CUB IMAGES ABE USUAIiliT VAGUE. For the ordinary ' analytic ' psychology, each sensibly discernible element of the object imagined is repre- sented by its own separate idea, and the total object is imagined by a * cluster * or * gang ' of ideas. We have seen abundant reason to reject this view (see p. 276 ff.). An imagined object, however complex, is at any one moment thought in one idea, which is aware of all its qualities to- gether. If I slip into the ordinary way of talking, and speak of various ideas * combining,* the reader will under- stand that this is only for popularity and convenience, and he will not construe it into a concession to the atomistic theory in psychology. Hume was the hero of the atomistic theory. Not only were ideas copies of original impressions made on the sense- organs, but they were, according to him, completely ade- quate copies, and were all so separate from each other as to possess no manner of connection. Hume proves ideas in the imagination to be completely adequate copies, not by appeal to observation, but by a priori reasoning, as fol- lows: **The mind cannot form any notion of quantity or quality, without forming a precise notion of the degrees of each," for *"t is confessed that no object can appear to the senses : or in other words, that no im- pression* can become present to the mind, without being determined in its degrees both of quantity and quality. The confusion in which im- pressions are sometimes involved proceeds only from their faintness and unsteadiness, not from any capacity in the mind to receive any im- pression, which in its real existence has no particular degree nor pro- portion. That is a contradiction in terms; and even implies the flattest * Impression means sensation for Hume. 46 PSTCHOLOOT, of all contradictions, viz., that 'tis possible for the same thing both to be and not to be. Now since all ideas are derived from impressions, and are nothing but copies and representations of them, whatever is true of the one must be acknowledged concerning the other. Impres- sions and ideas differ only in their strength and vivacity. The forego- ing conclusion is not founded on any particular degree of vivacity. It cannot therefore be affected by any variation in that particular. An idea is a weaker impression ; and as a strong impression must neces- sarily have a determinate quantity and quality, the case must be the same with its copy or representative." * The slightest introspectiTe glance will show to anyone the falsity of this opinion. Hume surely had images of his own works without seeing distinctly every word and letter upon the pages which floated before his mind's eye. His dictum is therefore an exquisite example of the way in which a man will be blinded by a priori theories to the most flagrant facts. It is a rather remarkable thing, too, that the psychologists of Hume's own empiricist school have, as a rule, been more guilty of this blindness than their opponents. The fundamental feuds of consciousness have been, on the whole, more accurately reported by the spiritualistic writers. None of Hume's pupils, so far as I know, until Taine and Huxley, ever took the pains to con- tradict the opinion of their master. Prof. Huxley in his brilliant little work on Hume set the matter straight in the following words : ** When complex impressions or complex ideas are reproduced as memories, it is probable that the copies never give all the details of the originals with perfect accuracy, and it is certain that they rarely do so. No one possesses a memory so good, that if he has only once observed a natural object, a second inspection does not show him something that he has forgotten. Almost all, if not all, our memories are therefore sketches, rather than portraits, of the originals — the salient features are obvious, while the subordinate characters are obscure or unrepre- sented. **Now, when several complex impressions which are more or less different from one another— let us say that out of ten impressions in each, six are the same in all, and four are different from all the rest — are successively presented to the mind, it is easy to see what must be the nature of the result. The repetition of the six similar impressions will strengthen the six corresponding elements of the complex idea, * Treatise on Human Nature, part i. § vii. IMAGINATION. 47 #hich will therefore acquire greater yividness ; while the four differing impressions of each will not only acquire no greater strength than they had at first, but, in accordance with the law of association, they will all tend to appear at once, and will thus neutralize one another. *'This mental operation may be rendered comprehensible by consid- ering what takes place in the formation of compound photographs — when the images of the faces of six sitters, for example, are each re- ceived on the same photographic plate, for a sixtn of the time requisite to take one portrait. The final result is that all those points in which the six faces agree are brought out strongly, while all those in which they differ are left vague ; and thus what may be termed a generic por- trait of the six, in contradistinction to a specific portrait of any one, is produced. ''Thus our ideas of single complex impressions are incomplete in one way, and those of numerous, more or less similar, complex im- pressions are incomplete in another way ; that is to say, they are gen- eric, not specific. And hence it follows that our ideas of the impres- sions in question are not, in the strict sense of the word, copies of those impressions ; while, at the same tiine^ they may exist in the mind in- dependently of language. *' The generic ideas which are formed from several similar, but not identical, complex experiences are what are called abstract or general ideas ; and Berkeley endeavored to prove that all general ideas are nothing but particular ideas annexed to a certain term, which gives them a more extensive signification, and makes them recall, upon oc- casion, other individuals which are similar to them. Hume says that he regards this as 'one of the greatest and the most valuable discover- ies that has been made of late years in the republic of letters/ and en- deavors to confirm it in such a manner that it shall be * put beyond all doubt and controversy. ' ** I may venture to express a doubt whether he has succeeded in his object ; but the subject is an abstruse one ; and I must content my- self with the remark, that though Berkeley's view appears to be largely applicable to such general ideas as are formed after language has been acquired, and to all the more abstract sort of conceptions, yet that gen- eral ideas of sensible objects may nevertheless be produced in the way indicated, and may exist independently of language. In dreams, one sees houses, trees, and other objects, which are perfectly recognizable as such, but which remind one of the actual objects as seen ' out of the corner of the eye,' or of the pictures thrown by a badly-focussed magic lantern. A man addresses us who is like a figure seen in twilight ; or we travel through countries where every feature of the scenery is vague ; the outlines of the hills are ill-marked, and the rivers have no defined banks. They are, in short, generic ideas of many past impressions of men, hills, and rivers. An anatomist who occupies himself intently with the examination of several specimens of some new kind of animal, in course of time acquires so vivid a conception of its form and struc- 48 PSrCHOLOOY, tare that the idea may take visible shape and become a sort of waking dream. But the figure which thus presents itself is generic, not spe- cific. It is no copy of any one specimen, but, more or less, a mean of the series ; and there seems no reason to doubt that the minds of chil- dren before they learn to speak, and of deaf-mutes, are peopled wi»h similarly generated generic ideas of sensible objects." * Are Vague Images * Abstract Ideas ' ? The only point which I am tempted to criticise in this account is Prof. Huxley's identi/ication of these generic images with ' abstract or general ideas ' in the sense of universal concep- tions, Taine gives the truer view. He writes : **8ome years ago I saw in England, in Kew Gardens, for the first time, araucarias, and I walked along the beds looking at these strange plants, with their rigid bark and compact, short, scaly leaves, of a sombre green, whose abrupt, rough, bristling form cut in upon the fine softly-lighted turf of the fresh grass-plat. If I now inquire what this experience has left in me, I find, first, the sensible representation of an araucaria ; in fact, I have been able to describe almost exactly the form and color of the plant. But there is a difference between this represen- tation and the former sensations, of which it is the present echo. The internal semblance, from which I have just made my description, is vague, and my past sensations were precise. For, assuredly, each of the araucarias I saw then excited in me a distinct visual sensation ; there are no two absolutely similar plants in nature ; I observed perhaps twenty or thirty araucarias ; without a doubt each one of them differed from the others in size, in girth, by the more or less obtuse angles of its branches, by the more or less abrupt jutting out of its scales, by the style of its texture ; consequently, my twenty or thirty visual sensations were different. But no one of these sensations has completely survived in its echo ; the twenty or thirty revivals have blunted one another ; thus upset and agglutinated by their resemblance they are confounded together, and ray present representation is their residue only. This is the product, or rather the fragraent, which is deposited in us, when we have gone through a series of sirailar facts or individuals. Of our numerous experiences there remain on the following day four or tive more or less distinct recollections, which, obliterated themselves, leave behind in us a simple colorless, vague representation, into which enter as components various reviving sensations, in an utterly feeble, incom- plete, and abortive state. — But thU representation is not the general aiid abstract idea. It is but its accompaniment^ and, if I may say so, the ore from which it is extracted. For the representation, though badly sketched, is a sketch, the sensible sketch of a distinct individual. . . . But my abstract idea corresponds to the whole class ; it differs, then, from the representation of an individual.— Moreover, my abstract idea ♦ Huxley's Hume. pp. 92-04. IMAGINATION. 49 is perfectly dear and determinate ; now that I pofisees it, I never fail to recognize an araucaria among the various plants which-may be shown me ; it differs then from the confused and floating representation I have of some particular araucaria.^' * In other words, a blurred picture is just as much a single mental fact as a sharp picture is ; and the use of either picture by the mind to symbolize a whole doss of individuals is a new menJtcd function, requiring some other modification of con- sciousness than the mere perception that the picture is distinct or not I may bewail the indistinctness of my mental image of my absent friend. That does not prevent my thought from meaning him alone, however. And I may mean all mankind, with perhaps a very sharp image of one man in my mind's eye. The meaning is a function of the more 'transitive' parts of consciousness, the 'fringe' of relations which we feel surrounding the image, be the latter sharp or dim. This was explained in a previous place (see p. 473 flf., especially the note to page 477), and I would not touch upon the matter at all here but for its historical interest Our ideas or images of past sensible experiences may then be either distinct and adequate or dim, blurred, and incomplete. It is likely that the different degrees in which different men are able to make them sharp and complete has had something to do with keeping up such philosophic disputes as that of Berkeley with Locke over abstract ideas. Locke had spoken of our possessing * the general idea of a triangle ' which " must be neither oblique nor rectangle, neither equilateral, equicrural, nor scalenon, but all and none of these at once." Berkeley says : . *' If any man has the faculty of framing in his mind such an idea of a triangle as is here described, it is in vain to pretend to dispute him out of it, nor would I go about it. All I desire is that the reader would fully and certainly inform himself whether he has such an idea or no." f Until very recent years it was supposed by all philoso- phers that there was a typical human mind which all indi- vidual minds were like, and that propositions of universal validity could be laid down about such faculties as ' the ♦ On Intelligence (N. Y.), vol. ii. p. 189. t Principles, Introd. g 18. Compare also the passage quoted above. p. 469 60 PBTOHOLOGT. ImaginatioiL' Lately, however, a mass of revelations liave poured in, which make us see how false a view this is. There are imaginations, not 'the Imagination,* and they must be studied in detail INDIVrDUAIiS DUVEB in mAQINATION. The first breaker of ground in this direction was Fechner, in 1860. Fechner was gifted with unusual talent for sub- jective observation, and in chapter xuv of his * Psychophy- sik* he gave the results of a most careful comparison of his own optical after-images, with his optical memory-pictures, together with accounts by several other individuals of their optical memory-pictures.* The result was to show a great * The differences noted by Fechner between after-images and imagei of imagination proper are as follows : Afier-imageB, Feel coercive ; Seem unsubstantial, vaporooB ; Are sharp in outline ; Are bright ; Are almost colorless ; Are continuously enduring ; Cannot be voluntarily changed. Are exact copies of origiDal& Are more easily got with shut than with open eyes ; Seem to move when the head or eyes move ; The field within which they appear (with closed eyes) is dark, con- tracted, flat, close to the eyes, in front, and the images have no perspective ; The attention seems directed for- wards towards the sense-organ, in observing after-images. ImaginaUon-imageB, Feel subject to our spontaneity ; Have, as it were, more body ; Are blurred ; Are darker than even the darkeflt black of the after-images ; Have lively coloration ; Incessantly disappear, and have to be renewed by an effort of will. At last even this fails to revive them. Can be exchanged at will for others. Cannot violate the necessary laws of appeacance of their originals— e. g. , a man cannot be imagined from in front and behind at once. The imagination must walk round him, so to speak ; Are more easily had with open than with shut eyes ; Need not follow movements of head or eyes. The field is extensive in three dimen- sions, and objects can be imagined in it above or behind almost as easily as in front. In imagining, the attention feels ak if drawn backwards towards th« brain. Finally, Fechner speaks of the impossibility of attending to both after IMAGINATION. 61 personal diversity. " It would be interesting," he writes, " to work up the subject statistically ; and I regret that other occupations have kept me from fulfilling my earlier intention to proceed in this way." I'echner's intention was independently executed by Mr. Galton, the publication of whose results in 1880 may be said to have made an era in descriptive Psychology. ** It is not necessary," says Gtelton, ** to trouble the reader with my early tentative steps. After the inquiry had been fairly started it took the form of submitting a certain number of printed questions to a laige number of persons. There is hardly any more difficult task than that of framing questions which are not likely to be misunderstood, which admit of easy reply, and which cover the ground of inquiry. I did my best in these respects, without forgetting the most important part of all — namely, to tempt my correspondents to write freely in fuller ex- planation of their replies, and on cognate topics as well. These sepa- rate letters have proved more instructive and interesting by far than the replies to the set questions. ** The first group of the ratbei long series of queries related to the illumination, definition, and violoring of the mental image, and were framed thus : ** * Before addressing yourself to any of the Questions on the opposite page« think of some definite object — suppose it is your breakfast-table as you sat down to it this morning — and consider carefully the picture that rises before your mind's eye. * * * 1 . lllu mination. — Is the image dim or fairly clear ? Is its bright- ness comparable to that of the actual scene ? ** * 2. Definition. — Are all the objects pretty well defined at the same time, or is the place of sharpest definition at any one moment more con- tracted than it is in a real scene ? ** * 3. Coloring. — Are the colors of the china, of the toast, bread-crust, mustard, meat, parsley, or whatever may have been on the table, quite distinct and natural ? ' ** The earliest results of my inquiry amazed me. I had begun by questioning friends in the scientific world, as they were the most likely class of men to give accurate answers concerning this faculty of visual- images and imagination -images at once, even when they are of the same object and might be expected to combine. All these differences are true of Fechner ; but many of them would be untrue of other persons. I quote them as a type of observation which any reader with sufllcient patience may repeat. To them may be added, as a universal proposition, that after- images seem larger if we project them on a distant screen, and smaller if we project them on a near one, whilst no such change takes place in mental liictures. 62 PBYCEOLOQT, izing, to which novelists and poets continually allude, which has left an abiding mark on the vocabularies of every language, and which supplies the material out of which dreams and the well-known halluci- nations of sick people are built. *' To my astonishment, I found that the great majority cfthe men of science to whom I first applied protested that mental imagery was unknoum to them, and they looked on me as fanciful and fantastic in supposing that the words * mental imagery ' really expressed what I believed everybody supposed them to mean. They had no more notion of its true nature than a color-blind man, who has not discerned his defect, has of the nature of color. They had a mental deficiency of which they were unaware, and naturally enough supposed that those who affirmed they possessed it were romancing. To illustrate their mental attitude it will be sufficient to quote a few lines from the letter of one of my correspondents, who writes : ** * These questions presuppose assent to some sort of a proposition re- garding the ** mind's eye," and the ** images" which it sees. . . . This points to some initial fallacy. ... It is only by a figure of speech that I can describe my recollection of a scene as a ** mental image " which lean ** see "with my *' mind's eye." ... I do not see it . . . anymore than a man sees the thousand lines of Sophocles which under duo pressure he is ready to repeat. The memory possesses it,' etc. ** Much the same result followed inquiries made for me by a friend among members of the French Institute. ** On the other hand, when I spoke to persons whom I met in gen- eral society, I found an entirely different disposition to prevail. Many men and a yet larger number of laomen, and many hoys and girls, declared that they habitually saw mental imagery, and that it teas perfectly distinct to them and full of color. The more I pressed and crossed-questioned them, professing myself to be incredulous, the more obvious was the truth of their first assertions. They described •their imagery in minute detail, and they spoke in a tone of surprise at my apparent hesitation in accepting what they said. I felt that I my- self should have spoken exactly as they did if I had been dc^icribing a scene that lay before my eyes, in broad daylight, to a blina man who persisted in doubting the reality of vision. Reassured by this happier experience, 1 recommenced to inquire among scientific men, and soon found scattered instances of what I sought, though in by no means the same abundance as elsewhere. I then circulated my questions more generally among my friends and through their hands, and obtained re- plies . . . from persons of both sexes, and of various ages, and in the end from occasional correspondents in nearly every civilized country. ** I have also received batches of answers from various educational establishments both in England and America, which were made after the masters had fully explained the meaning of the <|uestions, and in- terested the boys in them. These have the merit of returns derived from a general census, which my other data lack, because I cannot for IMAGINATION. 63 s moment suppose that the writers of the latter are a haphazard pro^ portion of those to whom they were sent. Indeed I know of some who, disavowing all possession of the power, and of many others who, pos' aessing it in too faint a degree to enable them to express what their experiences really were, in a manner satisfactory to themselves, sent no returns at all. Considerable statistical similarity was, however, ob- served between the sets of returns furnished by the schoolboys and those sent by my separate correspondents, and I may add that they ac- cord in this respect with the oral information I have elsewhere obtained. The conformity of replies from so many different sources which was clear from the first, the fact of their apparent trustworthiness being on the whole much increased by cross-examination (though I could give one or two amusing instances of break-down), and the evident eflbft made to give accurate answers, have convinced me that it is a much easier matter than I had anticipated to obtain trustworthy replies to psychological questions. Many persons, especially women and intelli- gent children, take pleasure in introspection, and strive their very best! to explain their mental processes. I think that a delight in self-dissee* tion must be a strong ingredient in the pleasure that many are said to take in confessing themselves to priests. '^ Here, then, are two rather notable results : the one is the proved facility of obtaining statistical insight into the processes of other per- sons' minds, whatever a priori objection may have been made as to its possibility ; and the other is that scientific men, as a class, have feeble powers of visual representation. There is no doubt whatever on the latter point, however it may be accounted for. My own conclusion is that an over-ready perception of sharp mental pictures is antagonistic to the acquirement of habits of highly-generalized and alxstract thought, especially when the steps of reasoning are carried on by words as symbols, and that if the faculty of seeing the pictures was ever possessed by men who think hard, it is very apt to be lost by disuse. The highest minds are probably those in which it is not lost; but subordinated, and is ready for use on suitable occasions. I am, however, bound to say that the missing faculty seems to be replaced so servieeably by other modes of conception, chiefly, I believe, connected with the incipient motor sense, not of the eyeballs only but of the muscles generally, that inert who d&dare themselves entirely deficient in the poiver of seeing mental pictures can nevertheless give lifelike de.scriptions of what they have seen, and can otherwise express themselves as if they were gifted with a vivid visual imagination. They can also become painters of the rank of Royal Academicians* , . . ♦ [I am myself a good draughtsman, and have a very lively interest in pictures, statues, architecture and decoration, and a keen sensibility to artistic effects. But I am an extremely poor vlsualizer, and find myself often unable to reproduce in my mind's eye pictures which I liave most carefully examined.— W. J.] 54 PBTCHOLOGY. *^ It is a mistake to suppose that sharp sight is accompanied by clear visnal memory. I have not a few instances in which the independence of the two faculties is emphatically commented on ; and I have at least one clear case where great interest in outlines and accurate appreciation of straightness, squareness, and the like, is unaccompanied by the power of visualizing. Neither does the faculty go with dreaming. I have cases where it is powerful, and at the same time where dreams are rare and faint or altogether absent. One friend tells me that his dreams have not the hundredth part of the vigor of his waking fancies. ''The visualizing and the identifying powers are by no means nec- essarily combined. A distinguished writer on metaphysical topics as- sures me that he is exceptionally quick at recognizing a face that he has seen before, but that he cannot call up a mental image of any face with clearness. '* Some persons have the power of combining in a single perception more than can be seen at any one moment by the two eyes. . . . " I find that a few persons can, by what they often descriBe as a kind of touch-sight, visualize at the same moment all round the image of a solid body. Many can do so nearly, but not altogether round that of a terrestrial globe. An cmment mineralogist assures me that he is able to imagine simultaneously all the sides of a crystal with which he is familiar. I may be allowed to quote a curious faculty of my own in respect to this. It is exercised only occasionally and in dreams, or rather in nightmares, but under those circumstances I am perfectly conscious of embracing an entire sphere in a single perception. It ap- pears to lie within my mental eyeball, and to be viewed contripetally. **Thi8 power of comprehension is practically attained in many cases by indirect methods. It is a common feat to take in the whole sur- roundings of an imagined room with such a rapid mental sweep as to leave some doubt whether it has not been viewed simultaneously. Some persons have the habit of viewing objects as though they were partly transparent ; thus, if they so dispose a globe in their imagination as to see both its north and south poles at the same time, th<3y will not be able to see its equatorial parts. They can also perceive all the rooms of an imaginary house by a single mental glance, the walls and floors being as if made of glass. A fourth chiss of {Persons have the habit of recall- ing scenes, not from the point of view whence they were observed, but from a distance, and they visualize their own selves as actors on the mental stage. By one or other of th(«e ways, the power of seeing the whole of an object, and not merely one as|)ect of it, is possessed by many persons. **The place where the image appears to lie differs much. Most per- sons see it in an indefinable sort of way, others see it in front of the eye, others at a distance corresponding to reality. There exists a power which is rare naturally, but can, I believe, be acquired without much difficulty, of projecting a mental picture upon a piece of paper, and of IMAGINATION. 55 holding it fast there, so that it can be outlined with a pencil. To this I shall recur. ''Images usually do not become stronger by dwelling on them; the first idea is commonly the most vigorous, but this is not always the case. Sometimes the mental view of a locality is inseparably connected with the sense of its position as regards the points of the compass, real or imaginary. I have received full and curious descriptions from very different sources of this strong geographical tendency, and in one or two cases I have reason to think it allied to a considerable faculty of geographical comprehension. '' The power of visualizing is higher in the female sex than in the male, and is somewhat, but not much, higher in public-school boys than in men. After maturity is reached, the further advance of age does not seem to dim the faculty, but rather the reverse, judging from numerous statements to that effect; but advancing years are sometimes accom- panied by a growing habit of hard abstract thinking, and in these cases — not uncommon among those whom I have questioned — the faculty undoubtedly becomes impaired. There is reason to believe that it is very high in some young children, who seem to spend years of difficulty in distinguishing between the subjective and objective world. Language and book-learning certainly tend to dull it. ** The visualizing faculty is a natural gift, and, like all natural gifts, has a tendency to be inherited. In this faculty the tendency to inheri- tance is exceptionally strong, as I have abundant evidence to prove, especially in respect to certain rather rare peculiarities, . . . which, when they exist at all, are usually found among two, three, or more brothers and sisters, parents, children, uncles and aunts, and cousins. ** Since families differ so much in respect to this gift, we may suppose that races would also differ, and there can be no doubt that such is the case. I hardly like to refer to civilized nations, because their natural faculties are too much modified by education to allow of their being appraised in an off-hand fashion. I may, however, speak of the French, who appear to possess the visualizing faculty in a high degree. The peculiar ability they show in prearranging ceremonials and fetes of all kinds, and their undoubted genius for tactics and strategy, show that ihey are able to foresee effects with unusual clearness. Their ingenuity in all technical contrivances is an additional testimony in the same direc- tion, and so is their singular clearness of expression. Their phrase * figurez-vous,' or ' picture to yourself,' seems to express their dominant mode of perception. Our equivalent of * imagine ' is ambiguous. *' I have many cases of persons mentally reading off scores when playing the pianoforte, or manuscript when they are making speeches. One statesman has assured me that a certain hesitation in utterance which he has at times is due to his being plagued by the image of his 66 PaTCHOLOQT. manuscript speech with its original erasures and corrections. He catt- not lay the ghost, and he puzzles in trying to decipher it. ** Some few persons see mentally in print every word that is uttered; they attend to the visual equivalent and not to the sound of the words, and they read them off usually as from a long imaginary strip of paper, such as is unwound from telegraphic instruments." The reader will find further details in Mr. Galton's •Inquiries into Human Faculty,' pp. 83-114.* I have myself for many years collected from each and all of my psychology-students descriptions of their own visual imagination ; and found (together with some curious idio- syncrasies) corroboration of all the variations which Mr. Galton reports. As examples, I subjoin extracts from two cases near the ends of the scale. The writers are first cous- ins, grandsons of a distinguished man of science. The one who is a good visualizer says : ** This morning's breakfast-tAble is both dim and bright; it is dim if I try to think of it when my eyes are open upon any object; it is per- fectly clear and bright if I think of it with my eyes closed. — ^All the objects are clear at once, yet when I confine my attention to any one object it becomes far more distinct. — I have more power to recall color than any other one thing: if, for example, I were to recall a plate deco- rated with flowers I could reproduce in a drawing the exact tone, etc. The color of anything that was on the table is perfectly vivid. — There is very little limitation to the extent of my images; I can see all four sides of a room, I can see all four sides of two, three, four, even more rooms with such distinctness that if you should ask me what was in any particular place in any one, or ask me to count the chairs, etc., I could do it without the least hesitation. — The more I learn by heart the more clearly do I see images of my pages. Even before I can recite the lines I see them so that I could give them very slowly word for word, but my mind is so occupie timely loss upon the members of the family. " t Psychologic du Ralsonnement (1886), p. 25. IMAGINATION. 61 dividaals afflicted with the mania that they are victims of persecution, may all belong to the auditory type ; and that the predominance of a certain kind of imagination may predispose to a certain order of hal« Incinations, and perhaps of delirium. •The motor type remains— perhaps the most interesting of all, and certainly the one of which least is known. Persons who belong to this type [les moteurs, in French, mottles, as Mr. Galton proposes to call them in English] make use, in memory, reasoning, and all their intellectual operations, of images derived from movement. In order to understand this important point, it is enough to remember that ' all our perceptions, and in particular the important ones, those of sight and touch, contain as integral elements the movements of our eyes and limbs ; and that, if movement is ever an essential factor in our really seeing an object, it must be an equally essential factor when we see the same object in imagination ' (Ribot).* For example, the complex im- pression of a ball, which is there, in our hand, is the resultant of optical impressions of touch, of muscular adjustments of the eye, of the move- ments of our fingers, and of the muscular sensations which these yield. When we imagine the ball, its idea must include the images of these muscular sensations, just as it includes those of the retinal and epider- mal sensations. They form so many motor images. If they were not earlier recognized to exist, that is because our knowledge of the muscu- lar sense is relatively so recent. In older psychologies it never was mentioned, the number of senses being restricted to five. ** There are persons who remember a drawing better when they have followed its outlines with their finger. Lecoq de Boisbaudran used this means in his artistic teaching, in order to accustom his pupils to draw from memory. He made them follow the outlines of figures with a pencil held in the air, forcing them thus to associate muscular with visual memory. Galton quotes a curious corroborative fact. Colonel Moncrieff often observed in North America young Indians who, visit- ing occasionally his quarters, interested themselves greatly in the engravings which were shown them. One of them followed with care with the point of his knife the outline of a drawing in the Illustrated London News, saying that this was to enable him to carve it out the better on his return home. In this case the motor images were to * [I am myself a very pour visualizer, and find that I can seldom call to mind even a single letter of the alphabet in purely retinal terms. I must trace the letter by running my mental eye over its contour in order that the image of it shall have any distinctness at all. On questioning a large Dumber of other people, mostly students, I find that perhaps half of them aay they have no such difllculty in seeing letters mentally. Many affirm that they can see an entire word at once, especially a short one like ' dog/ with no such feeling of creating the letters successively by tracing them with the eye.— W. J.l 62 P8TCH0L0QT. reinforce the visual ones. The young savage was a motor,* . . . When one^s motor images are destroyed, one loses one^s remembrance of move- ments, and sometimes, more curiously still, one loses the power of exe- cuting them. Pathology gives us examples in motor aphasia, agraphia, etc. Take the case of agraphia. An educated man, knowing how to write, suddenly loses this power, as a result of cerebral injury. His hand and arm are in no way paralytic, yet he cannot write. Whence this loss of power ? He tells us himself : he no longer knows how. He has forgotten how to set about it to trace the letters, he has lost the memory of the movements to be executed, he has no longer the motor images which, when formerly he wrote, directed his hand. . . . Other patients, affected with word-blindness, resort to these motor images precisely to make amends for their other deficiency. . . . An individ- ual affected in this way cannot read letters which are placed before his eyes, even although his sight be good enough for the purpose. This loss of the power of reading by sight may, at a certain time, be the only trouble the patient has. Individuals thus mutilated succeed in reading by an ingenious roundabout way which they often discover themselves : it is enough that they should trace the letters with their finger to under* stand their sense. What happens in such a case ? How can the hand supply the place of the eye? The motor image gives the key to the problem. If the patient can read, so to speak, with his fingers, it ia because in tracing the letters he gives himself a certain number of mus- cular imjiressions which are those of writing. In one word, the patient reads by writing (Charcot): the feeling of the graphic movements sug- gests the sense of what is being written as well as sight would." f The imagination of a blind-deaf mute like Laura Bridg- man must be confined entirely to tactile and motor materiaL AU Uind persons viust belong to the * tactile ' and ^motile' types of the French authors. When the young man whose cataracts were removed by Dr. Franz was shown diflferent geometric figures, he said he " had not been able to form from them the idea of a square and a disk until he perceived a sensa- tion of what he saw in the points of his fingers, as if he really touched the objects." % Professor Strieker of Vienna, who seems to have the motile form of imagination developed in unusual strength, * It is hardly needful to say that in modem primary education, in which the blackboard is so much used, the children are taught their letters, etc., by all possible channels at once, sight, hearing, and movement. t See an interesting case of a similar sort, reported by F&rges, in l'Sn< c6phale. 7me Ann6e, p. 545. X Philosophical Transactions, 1841, p. 66. IMAOINATION. 63 has given a very careful analysis of liis own case in a couple of monographs with which all students should be- come familiar.* His recollections both of his own move- ments and of those of other things are accompanied invariably by distinct muscular feelings in those parts of his body which would naturally be used in efifecting or in following the movement In thinking of a soldier march- ing, for example, it is as if he were helping the image to march by marching himself in his rear. And if he sup- presses this sympathetic feeling in his own legs, and con- centrates all his attention on the imagined soldier, the latter becomes, as it were, paralyzed. In general his imagined movements, of whatsoever objects, seem paralyzed the moment no feelings of movement either in his own eyes or in his own limbs accompany them.t The movements of articidate speech play a predominant part in his mental life. ** When after my experimental work I proceed to its description, as a rule I reproduce in the first instance only words, which I had already associated with the perception of the various details of the ob- servation whilst the latter was goifag on. For speech plays in all my observing so important a part that I ordinarily clothe phenomena in words as fast as I observe them." % Most persons, on being asked in what sort of terms they imagine ivords, will say * in terms of hearing.' It is not until their attention is expressly drawn to the point that they find it difficult to say whether auditory images or motor images connected with the organs of articulation predomi- nate. A good way of bringing the difficulty to consciousness is that proposed by Strieker : Partly open yout" mouth and then imagine any word with labials or dentals in it, such as * bubble,' * toddle.' Is your image under these conditions distinct ? To most people the image is at first * thick,* as the sound of the word would be if they tried to pronounce it with the lips parted. Many can never imagine the words • Studien Uber die SprachvorstellungeD (1880), and Studien Uber die Bewegungsvorstellungen (1882). t Prof. Strieker admits that by practice he has succeeded in making his eye-movements 'act vicariously' for his leg-movements in imagining men walking. t Bewegungsvorstellungen, p. 6. 84 P8T0E0L0Q7. clearly with the month open ; others sncceed after a few preliminary trials. The experiment proves how dependent our verbal imagination is on actual feelings in lips, tongne^ throat, larynx, etc. ^* When we recall the imflressioii of a word or sentence, if we do not speak it ont, we feel the witter of the organs just about to come to that po'nt. The articulating parts— the larynx, the tongue, the lips- are all sensibly excited ; a suppressed articulation is in fact the mate" rial cf our reooUection, the intellectual manifestation; the idea of speech."* The open mouth in Strieker's experiment not only pre- vents actual articulation of the labials, but our feeling of its openness keeps us from imagining their articulation, just as a sensation of glaring light will keep us from strongly imagining darkness. In persons whose auditory imagination is weak, the articulatory image seems to con* stitute the whole material for verbal thought. Professor Strieker says that in his own case no auditory image enters into the words of which he thinks, t Like most psycholo- gists, however, he makes of his personal peculiarities a rule, and says that verbal thinking is normally and univer- sally an exclusively motor representation. / certainly get auditory images, both of vowels and of consonants, in addition to the articulatory images or feelings on which this author lays such stress. And I find that numbers of my students, after repeating his experiments, come to this conclusion. There is at first a difficulty due to the open mouth. That, however, soon vanishes, as does also the difficulty of thinking of one vowel whilst continuously sounding another. What probably remains true, however, is that most men have a less auditory and a more articu- latory verbal imagination than they are apt to be aware of. * Baia : Senses and Intellect, p. 839. t Stiulien aber Sprachvorstellungen, 28, 31, etc. Cf. pp. 49-50, etc. Against Strieker, see Stumpf, Tonpsychol., 155-162, and Revue Phi losophique, xx. 617. See also Paulhan, Rev. Philosophique, xvi. 40S Strieker replies to Paulhan in vol. xviii. p. 685. P. retorts in vol. xix p. 118. Strieker reports that out of 100 persons questioned he found odI> one who had no feeling in his lips when silently thinking the letters M B^ P; and out of 60 only two who were conscious of no internal articulation whilst reading (pp. 59-60). IMAQIHiATlON. 65 Professor Strieker himself has acoustio images, and can imagine the sounds of musical instruments, and the pecul- iar voice of a friend. A statistical inquiry on a large scale, into the variations of acoustic, tactile, and motor imagina- tion, would probably bear less fruit than Galton's inquiry into visual images. A few monographs by competent ob- servers, like Strieker, about their own peculiarities, would give much more valuable information about the diversities which prevail* T(yuchrimajge8 are very strong in some people. The most vivid touch-images come when we ourselves barely escape local injury, or when we see another injured. The place * I think it must be admitted that some people have no vivid substan- tive images in any department of tlieir sensibility. One of my students, an intelligent youth, denied so pertinaciously that there was anything in his mind at all when he thought, that I was much perplexed by his case. I my- self certainly have no such vivid play of nascent movements or motor images as Professor Strieker describes. When I seek to represent a row of soldiers marching, all I catch is a view of stationary legs first in one phase of movement and then in another, and these views are extremely imperfect and momentary. Occasionally (especially when I try to stimulate my imagination, as by repeating Victor Hugo's lines about the regiment, ** Leur pas est si correct, sans tarder ni courir, Qu*on croit voir des clseauz se fermer et s'ouvrir,") I seem to get an instantaneous glimpse of an actual movement, but it is to the last degree dim and uncertaiu. All these images seem at tirst as if purely retinal. 1 think, however, thut rapid eye-movements accompany them, though these latter give rise to such sliglit feelings that they are almost impossible of detection. Absolutely no leg-movements of my own are there ; in fact, to call such up arrests my imagination of the soldiers. My optical images are in general very dim. dark, fugitive, and contracted. It would be utterly impossible to draw from them, and yet I perfectly well distinguish one from the other. My auditory images are excessively inade- quate reproductions of their originals. I have no images of taste or smell. Touch-imagination is fairly distinct, but comes very little into play with most objects thought of. Neither is all my thought verbalized: for I have shadowy schemes of relation, as apt to terminate in a nod of the head or an expulsion of the breath as in a definite word. On the whole, vague images or sensations of movement inside of my head towards the various parts of space in which the terms I am thinking of either lie or are momentarily sym- bolized to lie together with movements of the breath through my pharynx and nostrils, form a by no means inconsiderable part of my thought-stuff, I doubt whether my difficulty in giving a clearer account is wholly a mat- ter of inferior power of introspective attention, though that doubtless plays its part. Attention, ceteris paribus^ must always be inferior in proportion lo the feebleness of the internal images which are offered it to hold on to^ 66 PSTCffOLoor. may then actaally tingle with tlie imaginary sensation — perhaps not altogether imaginary, since goose-flesh, pal- ing or reddening, and other evidences of actual mnscnlar contraction in the spot may result. *' An educated man,** says a writer who must always be quoted when it is question of the powers of imagination,* ** told me once that on entering his house one day he receiTed a shock from crashing the finger of one of his little children in the door. At the moment of his fright he felt a violent pain in the corresponding finger of his own body, and this pain abode with him three days.** The same author makes the following discrimination, which probably most men could verify : ** On the skin I easily succeed in bringing out suggested sensatioDfe wherever I will. But because it is necessary to protract the mental ef- fort I can only awaken such sensations as are in their nature prolonged, as warmth, cold, pressure. Fleeting seusations, as those of a prick, a out, a blow, etc., I am unable to call up, because I cannot imagine them ex abrupto with the requisite intensity. The sensations of the former order I can excite upon any part of the skin ; and they may become so lively that, whether I will or not, I have to pass my hand over the place Just as if it were a real impression on the skin.'' f Meyer's account of his oxen visfial images is very interest- ing ; and with it we may close our survey of diflferences be- tween the normal powers of imagining in different indi- viduals. ** With much practice,^ he says, ** I have succeeded in making it possible for me to call up subjective visual sensations at will. I tried all my experiments by day or at night with closed eyes. At first it was very difficult. In the first experiments which succeeded the whole picture was luminous, the shadows being given in u somewhat less stronat bluish light. In later experiments I saw the objects dark, witn bright outlines, or rather I saw outline drawings of them, bright on a ilark ground. I can compare these drawinj^ less to chalk drawings on a blackboard than to drawings made with phosphorus on a dark wr.U at night, though the phosphorus would show luminous vapors whicb were absent from my lines. If 1 wished, for example, to see a face, without intending that of a particular person, 1 saw the outline of a profile against the dark background. When I tried to repeat an ex- * Geo. Herm. Meyer, Untersuchiingcn iib. d. Physiol, d. Ner\'enfa8er (1843) , J). 233. For other cases see Tuke's Influence of Mind upon Body, chaps. II. and vii. t Meyer, op. cU. p. 238. niAOINATlON. 97 perimeDt of the elder Darwin I saw only the edges of the die as bright lines on a dark ground. Sometimes, however, I saw the die really white and its edges black ; it was then on a paler ground. I could soon at will change between a white die with black borders on a light field, and a black die with white borders on a dark field ; and I can do this at any moment now. After long practice . . . these experiments succeeded better still. I can now call before my eyes almost any object which I please, as a subjective appearance, and this in its own natural color and illumination. I see them almost always on a more or less light or dark, mostly dimly changeable ground. Even known faces I can see quite sharp, with the true color of hair and cheeks. It is odd that I see these faces mostly in profile, whereas those described [in the previous extract] were all full-face. Here are some of the final results of these experiments : *' 1) Some time after the pictures have arisen they vanish or change into others, without my being able to prevent it. ** 2) When the color does not integrally belong to the object, I cannot always control it. A face, e.g., never seems to me blue, but always in its natural color; a red cloth, on the other hand, I can sometimes change to a blue one. ** 8) I have sometimes succeeded in seeing pure colors without objects; they then fill the entire field of view. ** 4) I often fail to see objects which are not known to me, mere fic- tions of my fancy, and instead of them there will appear familiar ob- jects of a similar sort ; for instance, I once tried to see a brass sword- hilt with a brass guard, instead of which the more familiar picture of a rapier-guard appeared. '* 5) Most of these subjective appearances, especially when they were bright, left after-images behind them when the eyes were quickly opeued during their presence. For example, I thought of a silver stir- rup, and after I had looked at it a while I opened my eyes and for a long while afterwards saw its after-image. *' These experiments succeeded best when I lay quietly on my back and closed my eyes. I could bear no noise about me, as this kept the vision from attainin«5 the requisite intensity. The experiments succeed with me now so easily that I am surprised they did not do so at first, and I feel as though they ought to succeed with everyone. The im- portant point in them is to get the image sufficiently intense by the ex- clusive direction of the attention upon it, and by the removal of all disturbing impressions.^^ * The negative after-images tvhich succeeded upon Meyer's imagination ivhen he opened his eyes are a highly interest- ing, though rare, phenomeuou. So far as I know there is Meyer, op, cii. pp. 238-41. 68 P8T0H0L0QY. only one other published report of a similar experience.* It would seem that in such a case the neural process corre- sponding to the imagination must be the entire tract con- cerned in the actual sensation, even down as far as the retina. This leads to a new question to which we may now turn — of what is THB NEUBAL FBOCBSS WHICH UNDEBUES IMAaiNATIOB' f The commonly-received idea is that it is only a milder degree of the same process which took place when the thing now imagined was sensibly perceived. Professor Bain writes: ** Since a sensation in the first instance diffuses nerve-currents through the interior of the brain outwards to the organs of expression and movement,— the persistence of that sensation, after the outward exciting cause is withdrawn, can be but a continuance of the same dif- fusive currents, perhaps less intense, but not otherwise different. The shock remaining in the ear and brain, after the sound of thunder, must pass through the same circles, and operate in the same way as during the actual sound. We can have no reason for believing that, in this self-sustaining condition, the impression changes its seat, or passes into some new circles that have the special property of retaining it. Every part actuated after the shock must have been actuated by the shock, only more powerfully. With this single difference of intensity, the mode of existence of a sensation existing after the fact is essentially the same as its mode of existence during the fact. . . . Now if this be the case with impressions persisting when the cause has ceased, what view are we to adopt concerning impressions reproduced by mental causes alone, or without the aid of the original, as in ordinary recollection ? What is the manner of occupation of the brain with a resuscitated feeling of resistance, a smell or a sound ? There is only one answer that seems admissable. The reTteu^ed feeling occupies the very same parts, and in the same manner, as the original feeling, and no other parts, nor in any other assignable manner. I imagine that if our present knowledge of the brain had been present to the earliest speculators, this is the only ♦ That of Dr. Ch. Fer§ in the Revue Philosophique, xx. 364. Johannes H(lller*s account of hypnagogic hallucinations floating before the eyes for a few moments after these had been opened, seems to belong more to the category of spontaneous hallucinations (see his Physiology, London, 1842, p. 1894). It is impossible to tell whether the words in Wundt's Vorle- Bungen, i. 887, refer to a personal experience of his own or not ; probably not. 11 va sans dire that an inferior visunlizer like myself can get no such after-images. Nor have I as yet succeeded in getting report of any from my students. IMAGINATION. 69 hypothesis that wonid have occurred to them. For where shonld a past feeling be embodied, if not in the same organs as the feeling when, present ? It is only in this way that its identity can be preserved ; a feeling differently embodied would be a different feeling."* It is not plain from Professor Bain's text whether by the ' same parts ' he means only the same parts inside the hrain^ or the same peripheral parts also, as those occupied by the original feeling. The examples which he himself pro- ceeds to give are almost all cases of imagination of move- ment, in which the peripheral organs are indeed affected, for actual movements of a weak sort are found to accom- pany the idea. This is what we should expect. All cur- rents tend to run forward in the brain and discharge into the muscular system ; and the idea of a movement tends to do this with peculiar faciliiy. But the question remains : Do currents run hackvxird, so that if the optical centres (for example) are excited by * association ' and a visual ob- ject is imagined, a current runs down to the retina also, and excites that sympathetically with the higher tracts ? In other words, can peripheral sense-organs be excited from €xbove, or only from ivithout ? Are they excited in imagi- nation ? Professor Bain's instances are almost silent as to this point All he says is this : ** We might think of a blow on the hand until the skin were actually irritated and inflamed. The attention very much directed to any part of the body, as the great toe, for instance, is apt to produce a distinct feeling in the part, which we account for only by supposing a revived nerve-current to flow there, making a sort of false sensation, an influ- ence from within mimicking the influences from without in sensation proper. — (See the writings of Mr. Braid, of Manchester, on Hypnotism, etc.)" If I may judge from my own experience, all feelings of this sort are consecutive upon motor currents invading the skin and producing contraction of the muscles there, the muscles whose contraction gives ' goose-flesh ' when it takes place on an extensive scale. I never get a feding in the skin, however strongly I imagine it, until some actual change in the condition of the skin itself has occurred. The laruth seems to be that the cases where peripheral * Senses and Intellect, p. 888. 70 PSYCHOLOGY. sense-organs are directly excited in consequence of imag^ • nation are exceptional rarities, if they exist at alL In oam^ mon cases of imagination it tvotild seem more natural to suppose that the seat of the process is purely cerebral^ and that the sense-- organ is left out. Beasons for such a conclusion would be briefly these : 1) In imagination the starting-point of the process must be in the brain. Now we know that currents usually flow one way in the nervous system ; and for the peripheral sense- organs to be excited in these cases, the current would have to flow backward. 2) There is between imagined objects and felt objects a diflFerence of conscious quality which may be called al- most absolute. It is hardly possible to confound the live- liest image of fancy with the weakest real sensation. The felt object has a plastic reality and outwardness which the imagined object wholly lacks. Moreover, as Fechner says, in imagination the attention feels as if drawn backwards to the brain ; in sensation (even of after-images) it is directed forward towards the sense-organ.* The diflFerence between the two processes feels like one of kind, and not like a mere •more ' or * less ' of the same.f If a sensation of sound were only a strong imagination, and an imagination a weak sensation, there ought to be a border-line of experience where we never could tell whether we were hearing a weak sound or imagining a strong one. In comparing a present sensation felt with a past one imagined, it will be remem- bered that we often judge the imagined one to have been the stronger (see above, p. 500, note). This is inexplicable if the imagination be simply a weaker excitement of the sen- sational process. To these reasons the following objections may be made : To 1) : The current demonstrably does flow backward * See above. Vol. II. p. 50, uote. t V. Kandinsky (Krilische u. klinische Betrachtungen im Gebiete der SinnesUluschungen (Berlin, 1885). p. 135 ff.) insists that in even the live- liest pseudo-hallucinations (see below, Chapter XX), whic h may be re- garded as the intensest possible results of the imaginative process, there is no outward objectivity perceived in the thing represented, and that a gamer Abgrund separates these • ideas' from true hallucination and objeo tive perception. IMAGINATION. 71 down the optic nerve in Meyer's and F^r^*s negative after- image. Therefore it can flow backward ; therefore it may flow backward in some, however slight, degree, in all imag- ination.* To 2) : The difference alleged is not absolute, and sensa- tion and imagination are hard to discriminate where the sensation is so weak as to be just perceptible. At nif2cht hearing a very faint striking of the hour by a far-off clock, our imagination reproduces both rhythm and sound, and it is often difficult to tell which was the last real stroke. So of a baby crying in a distant part of the house, we are un- certain whetiier we still hear it, or only imagine the sound Certain violin-players take advantage of this in diminuendo terminations. After the pianissimo has been reached they continue to bow as if still playing, but are careful not to touch the strings. The listener hears in imagination a * It seems to also flow backwards in certain hypnotic hallucinations. Suggest to a ' Subject' in the hypnotic trance that a sheet of paper has a red cross upon it, then pretend to remove the imaginary cross, whilst you tell the Subject to look fixedly at a dot upon the paper, and he will pres- ently tell you that he sees a ' bluish-green ' cross. The genuineness of the result has been doubted, but there seems no good reason for rejecting M Binet's account (Le Maguetisme Animal, 1887, p. 188). M. Biuet, following M. Parinaud, and on the faith of a certain experiment, al one time believed, the optical brain-centres and not the retina to be the seat of ordinary nega- tive after-images. The experiment is this: Look fixedly, wiih one eye open, at a colored spot on a white background. Then close that eye and look fixedly with the other eye at a plain surface. A negative after-image of the colored spot will presently appear. (Psychologie du Raisonnement, 1886, p. 45.) But Mr. Delabarre has proved (American Journal of Psy- chology, II. 826) that this afterimage is due, not to a higher cerebral pro- cess, but to the fact that the retinal process in the closed eye affects consciousness at certain moments, and that its object is ilu?n projected into the field seen by the eye which is open. M. Biuet informs me that he is converted by the proofs given by Mr. Delabarre. The fact remains, however, that the negative after-images of Ilerr Meyer, M. Fere, and the hypnotic subjects, form an exception to all that we know of nerve-currents, if they are due to a refluent centrifugal current to the retina. It may be that they will hereafter be explained in some other way. Meanwhile we can only write them down as a paradox. Sig. Sergi's theory that there is always a refluent wave in perception hardly merits serious con- sideration (Psychologie Physiologique, pp. 99, 189). Sergi's theory has recently been reaflirmcd with almost iucredihle crudity by Lombroso and Ottolenghi in the Revue Philosophique, xxix. 70 (Jan. 1890). 72 P8TCH0L0OT. degree of sound fainter still than the preceding pianissimo This phenomenon is not confined to hearing : *' If we slowly approach our finger to a surface of waj^r, we often deceive ourselves about the moment in which the wetting occora. The apprehensive patient believes himself to feel the knife of the surgeon whilst it is still at some distance/' "^ Yisual perception supplies numberless instances in which the same sensation of vision is perceived as one object or another according to the interpretation of the mind. Many of these instances will come before us in the course of the next two chapters ; and in Chapter XIX similar illusions will be described in the other senses. Taken together, all these facts would force us to admit that the subjective difference betiveen imagined and feU objects is less absolute than has been claimed, and that the cortical processes which underlie imagination and sensation are not quite as discrete as one at first is tempted to suppose. That peripheral sen^ sory processes are ordinarily involved in imagination seems improbable; that they may sometimes be aroused from the cortex dovmxoards cannot^ however^ be dogmatically denied. The imagination-process can then pass over into the sensO' tion-process. In other words, genuine sensations can be centrally originated. When we come to study hallucina- tions in the chapter on Outer Perception, we shall see that this is by no means a thing of rare occurrence. At present, however, we must admit that normally the tioo processes do KOT pass over into each other; and we must inquire why. One of two things must be the reason. Either 1. Sensation-processes occupy a different locality from imagination-processes ; or 2. Occupying the same locality, they have an intensity which under normal circumstances currents from other cortical regions are incapable of arousing, and to produce which currents from the periphery are required. It seeins almost certain (after what was said in Chapter II. pp. 49-51) that the imagination-process differs from the sensation-process by its intensity rather than by its locality. However it may be with lower animals, the assumption that ♦ Lotze, Med. Psych, p. 509. IMAGINATION. 73 ideational and sensorial centres are locally distinct appears to be supported by no facts drawn from the observation of human beings. After occipital destruction, the hemianop- sia which results in man is sensorial blindness, not mere loss c>f optical ideas. Were there centres for crude optical sensation below the cortex, the patients in these cases would still feel light and darkness. Since they do not pre- serve even this impression on the lost half of the field, we must suppose that there are no centres for vision of any sort whatever below the cortex, and that the corpora quadri- gemina and other lower optical ganglia are organs for reflex movement of eye-muscles and not for conscious sight Moreover there are no facts which oblige us to think that, within the occipital cortex, one part is connected with sen- sation and another with mere ideation or imagination. The pathological cases assumed to prove this are all better ex- plained by disturbances of conduction between the optical and other centres (see p. 50). In bad cases of hemianopsia the patient's images depart from him together with his sen- sibility to light They depart so completely that he does not even know what is the matter with him. To perceive that one is blind to the right half of the field of view one must have an idea of that part of the field's possible existence. But the defect in these patients has to be revealed to them by the doctor, they themselves only knowing that there is * something wrong ' with their eyes. What you have no idea of you cannot miss ; and their not definitely missing this great region out of their sight seems due to the fact that their very idea and memory of it is lost along with the sensation. A man blind of his eyes merely, sees darkness. A man blind of his visual brain-centres can no more see darkness out of the parts of his retina which are connected with the brain- lesion than he can see it out of the skin of his back. He cannot see at all in that part of the field ; and he cannot think of the light which he ought to be feeling there, for the very notion of the existence of that particular * there ' is cut out of his mind.* * See an important article by Binet in the Revue Pbilosophique, xxvi. 481 (1888) ; also Dufour, in Revue Med. de la Suisse Romande, 1889, No 8. citetic8 made so much account, is not fallacy of the senses proper, but rather of the intellect, tvhich interprets tvrongly what the senses give,* So much premised, let us look a little closer at these illusions. They are due to two main causes. The wrong object is perceived either because 1) Although not on this occasion the real cause, it is yet the habitual, inveterate, or most probable cause of * this ; ' or because 2) The mind is temporarily full of the thought of that object, and therefore * this ' is peculiarly prone to suggest it at this moment. I will give briefly a number of examples under each head. The first head is the more important, because it includes a number of constant illusions to which all men are subject, and which can only be dispelled by much experience. Illusions of the First Type, One of the oldest instances dates from Aristotle. Cross two fingers and roll a pea, pen- holder, or other small object be- tween them. It will seem double. Professor Groom Kohertson has given the clearest analysis of this illusiou. He observes that if the object be brought into con- tact first with the forefinger and uext with the second finger, the two contacts seem to come in at difierent points of space. * Cf. Th. Reid's Intellectual Powers, essay ii. chap, xxii, and A. Binet, in Mind, ix. 20G. M. Binet points out the fact that what is fallaciously inferred is always an object of some other sense than the ' this.' * Optical illusions ' are general ly errors of touch and muscular sensibility, and the fallaciously perceived object and the experiences which correct it are both tactile in these cases. Fig. 48. THE PERCEPTION OF THINGS. 87 The forefinger-touch seems higher, though the finger is really lower ; the second-finger-touch seems lower, though the finger is really higher. " We perceive the contacts as double because we refer them to two distinct parts of space." The touched sides of the two fingers are normally not together in space, and customarily never do touch one thing ; the one thing which now touches them, therefore, seems in two places, ie. seems two things.*^ There is a whole batch of illusions which come from optical sensations interpreted by us in accordance with our usual rule, although they are now produced by an unusual object The stereoscope is an example. The eyes see a picture apiece, and the two pictures are a little disparate, the one seen by the right eye being a view of the object taken from a point slightly to the right of that from which the left eye's picture is taken. Pictures thrown on the two eyes by solid objects present this identical disparity. Whence we react on the sensation in our usual way, and perceive a solid. If the pictures be exchanged we perceive a hollow mould of the object, for a hollow mould would cast just such disparate pictures as these. Wheatstone's instrument, the pseitdoscope, allows us to look at solid objects and see with each eye the other eye's picture. We then perceive the solid object hollow, if it be an object which might probaUy be hoUoto, but not otherwise. A human face, e.g., never appears hollow to the pseudoscope. In this irregularity of reaction on different objects, some seem hollow, others not ; the perceptive process is true to its law, which is always to react on the sensation in a deter- minate and figured fashion if possible, and in as probable a fashion as the case admits. To couple faces and hollow * The converse illusion is hard to bring about. The points a and b, being normally in contact, mean to us the same space, and hence it might be supposed that when simultaneously touched, us by a pair of callipers, we should feel but one object, whilst as a matter of fact we feci two. It should be remarked in explanation of this that an object placed between the two fingers in their normal uncrossed position always awakens the sense of two coniaeU. When the fingers are pressed together we feel one object to be between them. And when the fingers are crossed, and their correspond- ing points a and b simultaneously prM«frf, we do get something like tha illusion of singleness — that is, we get a very doubtful doubleness. 88 PSYCHOLOGY, ness violates all our habits of association. For the same reason it is very easy to make an intaglio cast of a face, or the painted inside of a pasteboard mask, look convex, in- stead of concave as they are. Our sense of the position of things with respect to our eye consists in suggestions of how we must move our hand to touch them. Certain places of the image on the retina, certain actively-produced positions of the eyeballs, are normally linked with the sense of every determinate posi- tion which an outer thing may come to occupy. Hence we perceive the usual position, even if the optical sensation be artificially brought from a different part of space. Prisms warp the light-rays in this way, and throw upon the retina the image of an object situated, say, at spot a of space in the same manner in which (without the prisms) an object situ- ated at spot h would cast its image Accordingly we feel for the object at b instead of a. If the prism be before one eye only we see the object at h with that eye, and in its right position a with the other — in other words, we see it double. If both eyes be armed with prisms with their angle towards the right, we pass our hand to the right of all objects when we try rapidly to touch them. And this illusory sense of their position lasts until a new association is fixed, when on removing the prisms a contrary illusion at first occurs. Passive or unintentional changes in the position of the eyeballs seem to be no more kept account of by the mind than prisms are ; so Me spontaneously make no allow- ance for them in our perception of distance and movements. Press one of the eyeballs into a strained position with the finger, and objects move and are translocated accordingly, just as when prisms are used. Curious illusions of movement in objects occur whenever the eyeballs move without our intending it. We shall learn in the following chapter that the original visual feeling of movement is produced by any image passing over the retina. Originally, however, this sensation is definitely referred neither to the object nor to the eyes. Such definite refer- ence grows up later, and obeys certain simple laws. We believe objects to move : 1) whenever we get the retinal movement-feeling, but think our eyes are still ; and 2) when- TUB PERCEPTION OF THINGS. 89 ever we think that our eyes move, but fail to get the retinal movement-feeling. We believe objects to be still, on the contrary, 1) whenever we get the retinal movement-feeling, but think 5ur eyes are moving ; and 2) whenever we neither think our eyes are moving, nor get the retinal movement- feeling. Thus the perception of the object's state of motion or rest depends on the notion we frame of our own eye's movement. Now many sorts of stimulation make our eyes move without our knowing it. If we look at a waterfall, river, railroad train, or any body which continuously passes in front of us in the same direction, it carries our eyes with it. This movement can be noticed in our eyes by a by- stander. If the object keep passing towards our left, our eyes keep following whatever moving bit of it may have caught their attention at first, until that bit disappears from view. Then they jerk back to the right again, and catch a new bit, which again they follow to the left, and so on indefinitely. This gives them an oscillating demeanor, slow involuntary rotations leftward alternating with rapid voluntary jerks rightward. But the oscillations continve for a while after the object has come to a standstill, or the eyes are carried to a new object, and this produces the illu- sion that things now move in the opposite direction. For we are unaware of the slow leftward automatic movements of our eyeballs, and think that the retinal movement-sen- sations thereby aroused must be due to a rightward motion of the object seen; whilst the rapid voluntary rightward movements of our eyeballs we interpret as attempts to pur- sue and catch again those parts of the object which have been slipping away to the left. Exactly similar oscillations of the eyeballs are produced in giddiness, with exatly similar results. Giddiness is easi- est produced by whirling on our heels. It is a feeling of the movement of our own head and body through space, and is now pretty well understood to be due to the irrita- tion of the semi-circular canals of the inner ear.* When, * Purkinje, Mach, and Breuer are the authors to whom we mainly owe the explanation of the feeling of vertigo. I have found (American Jour- nal of Otology. Oct. 1882) that in deaf-mutes (whose semi-circular canals or entire auditory nerves must often be disorganized) there very frequently exists no susceptibility to giddiness or whirling. 90 PSrCHOLOGT. after whirling, we stop, we seem to be spinning in the reverse direction for a few Seconds, and then objects appear to con- tinue whirling in the same direction in which, a moment previous, our body actually whirled. The reason is that our eyes normally tend to maintain their field of view. If we suddenly turn our head leftwards it is hard to make the eyes follow. They roll in their orbits rightwards, by a sort of compensating inertia. Even though we falseiy think our head to be moving leftwards, this consequence occurs, and our eyes move rightwards — as may be observed in any one with vertigo after whirling. As these move- ments are unconscious, the retinal movement-feelings which they occasion are naturally referred to the objects seen. And the intermittent voluntary twitches of the eyes towards the left, by which we ever and anon recover them from the extreme rightward positions to which the reflex movement brings them, simply confirm and intensify our impression of a leftward-whirling field of view : we seem to ourselves to be periodically pursuing and overtaking the objects in their leftward flight The w:hole phenomenon fades out after a few seconds. And it often ceases if we voluntarily fix our eyes upon a given point. ^ Optical vertigo, as these illusions of objective movement are called, results sometimes from brain-trOuble, intoxica- tions, paralysis, etc. A man will awaken with a weakness of one of his eye-muscles. An intended orbital rotation will then not produce its expected result in the way of retinal movement-feeling — whence false perceptions, of which one of the most interesting cases will fall to be discussed in later chapters. There is an illusion of movement of the opposite son, with which every one is familiar at raUtvay stations. Habit- ually, when we ourselves move forward, our entire field of view glides backward over our retina. When our move- ment is due to that of the windowed carriage, car, or boat ♦ The involuntary continuance of the eye's motions is not the only cause of the false perception in these cases. There is also a true negative after- image of the original retinal movement-sensations, as we shall see in Chapter XX. THE PERCEPTION OF THINOa, 91 in which we sit, all stationary objects visible through the window give us a sensation of gliding in the opposite direction. Hence, whenever we get this sensation, of a window with oR objects visible through it moving in one direction, we react upon it in our customary way, and per- ceive a stationary field of view, over which the window, and we ourselves inside of it, are passing by a motion of our own. Consequently when another train comes alongside of ours in a station, and fills the entire window, and, after standing still awhile, begins to glide away, we judge that it is our train which is moving, and that the other train is still. If, however, we catch a glimpse of any part of the station through the windows, or between the cars, of the other train, the illusion of our own movement instantly disappears, and we perceive the other train to be the one in motion. This, again, is but making the usual and probable inference from our sensation.* Another illusion due to movement is explained by Helm- holtz. Most wayside objects, houses, trees, etc., look small when seen out of the windows of a swift train. This is be- cause we perceive them in the first instance unduly near. And we perceive them unduly near because of their extra- ordinarily rapid parallactic flight backwards. Wlien we ourselves move forward all objects glide backwards, as aforesaid ; but the nearer they are, the more rapid is this apparent translocation. Relative rapidity of passage back- wards is thus so familiarly associated with nearness that when we feel it we perceive nearness. But with a given size of retinal image the nearer an object is, the smaller do we judge its actual size to be. Hence in the train, the faster we go, the nearer do the trees and houses seem, and the nearer they seem, the smaller do they look.t 4r Other illusions are due to the feeling of convergence being wrongly interpreted. When we converge our eyeballs we perceive an approximation of whatever thing we may be looking at Whatever things do approach whilst we look * We never, so far as I know, get the converse illusion at a railroad sta- tion and believe the other train to move v;hen it is still, t Helmholtz : Physiol. Optik, 365. 92 PSYCHOLOOT, at them oblige us, so long as they are not very distant, to converge our eyes. Hence approach of the thing is the prdb- aUe objective fact when we feel our eyes converging. Now in most persons the internal recti muscles, to which converg- ence is due, are weaker than the others ; and the entirely passive position of the eyeballs, the position which they assume when covered and looking at nothing in particular, is either that of parallelism or of slight divergence* Make a person look with both eyes at some near object, and then screen the object from one of his eyes by a card or book, The chances are that you will see the eye thus screened turn just a little outwards. Remove the screen, and you will now see it turn in as it catches sight of the object again. The other eye meanwhile keeps as it was at first To most persons, accordingly, all objects seem to come r^earer when, after looking at them with one eye, both eyes aire used ; and they seem to recede during the opposite change. With persons whose external recti muscles are insufficient, the illusions may be of the contrary kind. The size of the retinal image is a fruitful source of illusions. Normally, the retinal image grows larger as the object draws near. But the sensation yielded by this enlargement is also given by any object which really grows in size with- out changing its distance. Enlargement of retinal image is therefore an ambiguous sign. An opera-glass enlarges the moon. But most persons will tell you that she looks smaller through it, only a great deal nearer and brighter. They read the enlargement as a sign of approach ; and the perception of approach makes them actually reverse the sensation which suggests it — by an exaggeration of our habitual custom of making allowance of the apparent en- largement of whatever object approaches us, and reducing it in imagination to its natural size. Similarly, in the theatre the glass brings the stage near, but hardly seems to mag- nify the people on it. The well-known increased apparent size of the moon on the horizon is a result of association and probability. It is seen through vaporous air, and looks dimmer and duskier than when it rides on high; and it is seen over fields, trees. THE PERCEPTION OF THINQ8. 93 hedges, streams, and the like, which break up the interven- ing space and make us the better realize the latter's extent Both these causes make the moon seem more distant from ns when it is low ; and as its visual angle grows no less, we deem that it must be a larger body, and we so perceive it It looks particularly enormous when it comes up directly behind some well-known large object, as a house or tree, distant enough to subtend an angle no larger than that of the moon itsell* The feding of accommodation also gives rise to false per- ceptions of size. Usually we accommodate our eyes for an object as it approaches us. Usually under these circum- stances the object throws a larger retinal image. But believing the object to remain the same, we make allowance for this and treat the entire eye-feeling which we receive as significant of nothing but approach. When we relax our accommodation and at the same time the retinal image grows smaller, the probable cause is always a receding object The moment we put on convex glasses, however, the accommodation relaxes, but the retinal image grows larger instead of less. This is what would happen if our object, whilst receding, grew. Such a probable object we accordingly perceive, though with a certain vacillation as to the recession, for the growth in apparent size is also a probable sign of approach, and is at moments interpreted accordingly. — ^Atropin paralyzes the muscles of accommo- dation. It is possible to get a dose which will weaken these muscles without laming them altogether. When a known near object is then looked at we have to make the same voluntary strain to accommodate, as if it were a great deal nearer ; but as its retinal image is not enlarged in pro- portion to this suggested approach, we deem that it must have grown smaller than usual. In consequence of this so-called micropsy, Aubert relates that he saw a man ap- parently no larger than a photograph. But the small size again made the man seem farther off. The real distance ♦ Cf. Berkeley's Theory of Vision, §8 67-79 ; Helmholtz : Physiol ogische Optik, pp. 680-1 ; Lechalas in Reuve Philosophique, xxvi. 49. »4: PSYCHOLOGY. was two or three feet, and he seemed against the wall of the room.''^ Of these vacillations we shall have to speak again in the ensuing chapter.t Mrs. C. L. Franklin has recently described and explained with rare acuteness an illusion of which the most curious thing is that it was never noticed before. Take a single pair of crossed lines (Fig. 49), hold them in a horizontal plane before the eyes, and look along them, at such a distance that with the right eye shut, 1, and with the left eye shut, 2, looks like the projection of a vertical line. Look steadily now at the point of intersection of the lines with both eyes open, and you will see a third line sticking up like a pin through the paper at right angles to the plane of the Fio. 49. two first lined? The explanation of this illusion is very simple, but so circumstantial that I must refer for it to Mrs. Franklin's own account.^ Suffice it that images of the two lines fall on * corresponding ' rows of retinal points, and that the illusory vertical line is the only object capable of throwing such images. A variation of the experiment is this : ** In Fig. 50 the lines are all drawn so as to pass through a common point. With a little trouble one eye can be put into the position of this point — it is only necessary that the paper be held so that, with one eye shut, the other eye sees all the lines leaning neither to the right nor to the left. After a moment one can fancy the lines to be vertical staflfs standing out of the plane of the paper. . . . This illusion [says Mrs. Franklin] I take to be of purely mental origin. When a line lies any- where in a plane passing through the apparent vertical meridian of one eye, and is looked at with that eye only. ... we have no very good means of knowing how it is direetes phrase) out of our ovm head. At bottom this is only one case (and that the simplest e) of the general fact that our nerve-centres are an organ for reacting on sense-impressions, and that our hemispheres, in particular, are given us in order that records of our private past experience may co-operate in the reaction. Of course such a general way of stating the fact is vague ; and all those who follow the current theory of ideas will be prompt to throw this vagueness at it as a reproach. Their way of de- scribing the process goes much more into detail. The sen- sation, they say, awakens * images ' of other sensations asso- ciated with it in the past. These images * fuse,' or are * com- bined ' by the Ego with the present sensation into a new product, the percept, etc., etc. Something so indistinguish- able from this in practical outcome is what really occurs, that one may seem fastidious in objecting to such a state- ment, specially if have no rival theory of the elementary processes to propose. And yet, if this notion of images rising and flocking and fusing he mythological (and we have all along so considered it), why should we entertain it unless confessedly as a mere figure of speech ? As such, of course, it is convenient and welcome to pass. But if we try to put an exact meaning into it, all we find is that the brain reacts by paths which previous experiences have worn, and makes us usually perceive the probable thing, i.e., the thing by 104 P8TCH0L0G7, which on previous occasions the reaction was most frequent* ly aroused. But we can, I think, without danger of being too speculative, be a little more exact than this, and conceive of a physiological reason why the felt quality of an object changes when, instead of being apprehended in a mere sen- sation, the object is perceived as a thing. All consciousness seems to depend on a certain slowness of the process in the cortical cells. The rapider currents are, the less feeling they seem to awaken. If a region A, then, be so connected with another region B that every current which enters A immediately drains off into B, we shall not be very strongly conscious of the sort of object that A can make us feeL If B, on the contrary, has no such copious channel of dis- charge, the excitement will linger there longer ere it diffuses itself elsewhere, and our consciousness of the sort of ob- ject that B makes us feel will be strong. Carrying this to an ideal maximum, we may say that if A offer no resistance to the transmission forward of the current, and if the cur- rent terminate in B, then, no matter what causes may initiate the current, we shall get no consciousness of the object peculiar to A, but on the contrary a vivid sensation of the object peculiar to B. And this will be true though at other times the connection between A and B might lie less open, and every current then entering A might give us a strong con- sciousness of A's peculiar object. In other words, just in proportion as associations are habitual, will the qualities of the suggested thing tend to substitute themselves in con- sciousness for those of the thing immediately there; or, more briefly, just in proportion as an experience is probable vnll it tend to be directly fdt. In all such experiences the paths lie wide open from the cells first affected to those concerned with the suggested ideas. A circular after-image on the receding wall or ceiling is actually seen as an ellipse, a square after-image of a cross there is seen as slant-legged, etc., because only in the process correlated with the vision of the latter figures do the inward currents find a pause (see the next chapter). We must remember this when, in dealing with the eye, we come to point out the erroneousness of the principle laid THE PERCEPTION OF THINGS. 105 down by Beid and Helmholtz that true sensations can never be changed bj the suggestions of experience. A certain illusion of which I have not yet spoken affords an additional illustration of this. When tve tviU to execute a movement and the movement for some reason does not occur ^ urdesa the sensation of the part's not moving is a strong one, tve are apt to fed as if the mxyvement had actiutUy taken place. This seems habitually to be the case in anaesthesia of the moving parts. Close the patient's eyes, hold his anaesthetic arm still, and tell him to raise his hand to his head ; and when he opens his eyes he will be astonished to find that the movement has not taken place. All reports of anaesthetic cases seem to mention this illusion. Sternberg who wrote on the subject in 1885,* lays it down as a law that the intention to move is the same thing as the feeling of the motion. We shall later see that this is ialse (Chapter XXV); but it certainly may suggest the feeling of the motion with hallu- cinatory intensity. Sternberg gives the following experi- ment, which I find succeeds with at least half of those who try it : Rest your palm on the edge of the table with your forefinger hanging over in a position of extreme flexion, and then exert your will to flex it still more. The position of the other fingers makes this impossible, and j'et if we do not look to see the finger, we think we feel it move. He quotes from Exner a similar experiment with the jaws: Put some hard rubber or other unindentable obstacle between * In the Proceedings of the American Society for Psychical Research, pp. 25d-4. I have tried to account for some of the variations in this conscious- ness. Out of 140 persons whom I found to feel their lost foot, some did so dubiously. "Either they only feel it occasionally, or only when it puins them, or only when they try to move it; or they only feel it when ihe> ' think a g(X)d deal about it * and make an eflfort to conjure it up. When tliey 'grow inattentive,' the feeling 'flies back* or 'jumps back,' lo the stump. Every degree of consciousness, from complete and permanent hal- lucination down to something hardly distinguishable from ordinary fancy, seems represented in the sense of the missing extremity which these patients say they have. Indeed I have seldom seen a more plausible lot of evidence for the view that imagination and sensation are but differences of vividness in an identical process than these confessions, taking them alto- gether, contain. Many patients say they can hardly tell whether they feel or fancy the limb. ** 106 PSrCHOLOGT. your back teeth and bite hard : you think you feel the jaw move and the front teeth approach each other, though in the nature of things no movement can occur.* — The visu- al suggestion of the path traversed by the finger-tip as the locus of the movement-feeling in the joint, which we dis- cussed on page 41, is another example of this semi-hallu- cinatory power of the suggested thing. Amputated people, as we have learned, still feel their lost feet, etc. This is a necessary consequence of the law of specific energies, for if the central region correlated with the foot give rise to any feeling at all it must give rise to the feeling of a foot.t But the curious thing is that many of these patients can unll the foot to move, and when they have done so, distinctly /erf the movement to occur. They can, to use their own language, * work ' or * wiggle ' their lost toes. X Now in all these various cases we are dealing with data which in normal life are inseparably joined. Of all possi- ble experiences, it is hard to imagine any pair more uni- formly and incessantly coupled than the volition to move, on the one hand, and the feeling of the changed position of the parts, on the other. From the earliest ancestors of ours which had feet, down to the present day, the movement of the feet must always have accompanied the will to move them ; and here, if anywhere, habit's consequences ought to be found.:}: The process of the willing ought, then, to pour into the process of feeling the command effected, and ought to awaken that feeling in a maximal degree provided no other positively contradictory sensation come in at the same time. In most of us, when the will fails of its effect there is a contradictory sensation. We discern a resistance or the unchanged position of the limb. But neither in ansBS-' thesia nor in amputation can there be any contradictory sensation in the foot to correct us ; so imagination has aU the force of fact. ♦ Pflttger'8 Archiv, xxxvn. 1. t Not all patieuts have this additional illusion. 1 1 ought to say that in almost all cases the vc^tiOQ is followed hf actual contraction of muscles in the 9iumD, THE PERCEPTION OF THLNQ8. 107 • APPSBOEIFTION.' In (Germany smceHerbart's time Psychology has always had a great deal to say about a process called Apperception^^ The incoming ideas or sensations are said to be * apper- ceived ' by * masses ' of ideas already in the mind. It is plain that the process we have been describing as perception is, at this rate, an apperceptive process. So are all recogni- tion, classing, and naming ; and passing beyond these sim- plest suggestions, all farther thoughts about our percepts are apperceptive processes as well. I have myself not used the word apperception because it has carried very different mean, ings in the history of philosophy,! and 'psychic reaction,* * interpretation,' * conception,' * assimilation,' * elaboration,' or simply ' thought,' are perfect synonyms for its Herbartian meaning, widely taken. It is, moreover, hardly worth while to pretend to analyze the so-called apperceptive perform- ances beyond the first or perceptive stage, because their varia- tions and degrees are literally innumerable. * Apperception * is a name for the sum-total of the effects of what we have studied as association; and it is obvious that the things which a given experience will suggest to a man depend on what Mr. Le^es calls his entire psycliostatical conditions, his nature and stock of ideas, or, in other words, his charac- ter, habits, memory, education, previous experience, and momentary mood. We gain no insight into what really oc- curs either in the mind or in the brain by calling all these things the *apperceiving mass,' though of course this may upon occasion be convenient On the whole I am inclined to think Mr. Lewes's term of * assimilation ' the most fruit- ful one yet used.t Professor H. Steinthal has analyzed apperceptive pro- cesses with a sort of detail which is simply burdensome.^ ♦ Cf. Herbart, Psychol, als. Wissenschaft, § 125. t Compare the historical reviews by K. Lange : Ueber Apperception (Plauen, 1879), pp. 12-14; by Staude in Wundt's Philosophische Studicn, i. 149; and by Marty in Vierteljsch. f. wiss. Phil., x. 347 flf. X Problems, vol. i. p. 118 ff. g See his I^nleitimg in die Pisycbologie u. Sprachwissenschaft (1881 i p. 166 ff. 108 P870H0L0Q7. TTift introdnction of the matter may, however, be quoted He begins with an anecdote from a comic paper. ** In the compartment of a railway-carriage six persons unknown m each other sit in lively conversation. It becomes a matter of regret that one of the company must alight at the next station. One of the others says that he of all things prefers such a meeting with entirely unknown persons, and that on such occasions he is accustomed neither to ask who or what his companions may be nor to tell who or what he is. Another thereupon says that he will undertake to decide this question, if they each and all will answer him an entirely disconnected question. They began. He drew five leaves from his note-book, wrote a question on each, and gave one to each of his companions with the request that he write the answer below. When the leaves were returned to him, he turned, after reading them, without hesitation to the others, and said to the first, * You are a man of science '; to the second, ^ You are a sol dier'; to the third, * You are a philologer'; to the fourth, ' You are a journalist'; to the fifth, *You are a farmer.* All admitted that he was right, whereupon he got out and left the five behind. Ecah wished to know what question the others bad received; and behold, he had given the same question to each. It ran thus : *' * What being destroys what it has itself brought forth ? '*To this the naturalist had answered, * vital force'; the soldier, *war'; the philologist, *Kronos'; the publicist, * revolution '; the farmer, 'a boar\ This anecdote, methinks, if not true, is at least splendidly well invented. Its narrator makes the journalist go on to say : * Therein consists the joke. Each one answers the first thing that occurs to him,* and that is whatever is most newly related to his pur- suit in life. Every question is a hole-drilling experiment, and the an- swer is an oi)ening through which one sees into our interiors.' ... So do we all. We are all able to recognize the clergyman, the soldier, the scholar, the bu^jiness man, not only by the cut of their garments and the attitude of their body, but by what they say and how they express it. We guess the place in life of men by the interest which they show and the way in which they show it. by the objects of which they speak, by the point of view from which they regard things, judge them; conceive them, in short by their mode of apperceivingg . . . ** Every man has cue group of ideas which relate to his own person and interests, and another which is connected with society. Each has his group of ideas about plants, religion, law, art, etc., acd more especially about the rose, epic poetry, sermons free trade, and the like. Thus the mental content of every individual, even of the uneducated * One of my colleagues, asking himself the question after reading the tnecdote, tells me that he replied * Harvard College, ' the faculty of that body having voted, a few days previously, to keep back the degrees of members of the graduating class who might be disorderly on class-day night. W. J THE PBRCBPTION OF THINOB, 109 and of children, consists of masses or circles of knowledge of which each lies within some larger circle, alongside of others similarly in- cluded, and of which each includes smaller circles within itself. . . , The perception of a thing like a horse ... is a process between the present horse's picture before our eyes, on the one hand, and those fused or interwoven pictures and ideas of all the horses we hare ever seen, on the other; ... a process between two factors or momenta, of which one existed before the process and was an old possession of the mind (the group of ideas, or concept, namely), whilst the other is but just presented to the mind, and is the immediately supervening factor (the sense-impression). The former apperceives the latter; the latter is apperceived by the former. Out of their combination an api>erception- product arises: the knowledge of the perceived being as a horse. The earlier factor is relatively to the later one active and a priori ; the super- vening factor is given, a posteriori^ passive. ... We may then define Apperception as the movement of two masses of consciousness (Vorstel- luugsmassen) against each other so as to produce a cognition. ** The a priori factor we called active, the a posteriori factor passive, but this is only relatively true. . . . Although the a priori moment commonly shows itself to be the more powerful, apperception- processes can perfectly well occur in which the new observation transforms or en- riches the apperceiving group of ideas. A child who hitherto has seen none but four-cornered tables apperceives a round one as a table; but by this the apperceiving mass (* table ') is enriched. To his previous knowledge of tables comes this new feature that they need not be four- cornered, but may be round. In the history of science it has happened often enough that some discovery, at the same time that it was apper- ceived, i.e. brought into connection with the system of our knowledge, transformed the whole system. In principle, however, we must maintain thait, although either factor is both active and passive, the a priori factor is almost always the more active of the two." * This account of Steinthal's brings out very clearly the difference hettveen our psychological conceptions and what are called concepts in logic. In logic a concept is unalterable ; but what are popularly called our ' conceptions of things ' alter by being used. The aim of ' Science ' is to attain concep* tions so adequate and exact that we shall never need to- change them. There, is an everlasting struggle in every mind between the tendency to keep unchanged, and the tendency to renovate, its ideas. Our education is a cease- less compromise between the conservative and the pro- gressive factors. Every new experience must be disposed * Op. cit. pp. 166-171. 110 PaYCHOLOGY. of under some old head. The great point is to find the head which has to be least altered to take it in. Certain Polyne- sian natives, seeing horses for the first time, called them pigs, that being the nearest head. My child of two played for a week with the first orange that was given him, calling it a 'ball.' He called the first whole eggs he saw 'potatoes,' having been accustomed to see his * eggs ' broken into a glass, and his potatoes without the skin. A folding pocket- corkscrew he unhesitatingly called * bad-scissors.' Hardly any one of us can make new heads easily when fresh expe- riences come. Most of us grow more and more enslaved to the stock conceptions with which we have once become familiar, and less and less capable of assimilating impres- sions in any but the old ways. Old-fogyism, in short, is the inevitable terminus to which life sweeps us on. Objects which violate our established habits of * apperception ' are simply not taken account of at all ; or, if on some occasion we are forced by dint of argument to admit their existence, twenty-four hours later the admission is as if it were not, and every trace of the unassimilable truth has vanished from our thought Genius, in truth, means little more than the faculty of perceiving in an unhabitual way. On the other hand, nothing is more congenial, from babyhood to the end of life, than to be able to assimilate the new to the old, to meet each threatening violator or burster of our well-known series of concepts, as it comes in, see through its unwontedness, and ticket it oft' as an old friend in disguise. This victorious assimilation of the new is in fact the type of all intellectual pleasure. The lust for it is curiosity. The relation of the new to the old, before the assimilation is performed, is wonder. We feel neither curiosity nor wonder concerning things so far beyond us that we have no concepts to refer them to or standards by which to measure them.* The Fuegians, in Darwin's voy- * The great maxim in pedagogy is to knit every new piece of knowl- edge on ton pre-existing curiosity — i.e., to assimilate its matter in some way to what is already known. Hence the advantage of " comparing all that is far off and foreign to something that is near home, of making the unknown plain by the example of the known, and of connecting all the instruction with the personal experience of the pupil. ... If the teacher is THB PERCEPTION OF TEINOS. Ill age, wondered at the small boats, but took the big ship as a ' matter of course.' Only what we partly know already inspires us with a desire to know more. The more elabo- rate textile fabrics, the vaster works in metal, to most of us are like the air, the water, and the ground, absolute ex- istences which awaken no ideaa It is a matter of course that an engraving or a copper-plate inscription should pos- sess that degree of beauty. But if we are shown a pertr- drawing of equal perfection, our personal sympathy with the difficulty of the task makes us immediately wonder at the skill. The old lady admiring the Academician's picture, says to him : " And is it really all done by hand?'' IS FBBOEPTION UNCONSCIOITS INFEBSNCB P A widely-spread opinion (which has been held by such men as Schopenhauer, Spencer, Hartmann, Wundt, Helm- holtz, and latelt interestingly pleaded for by M. Binet *) will have it thsA^percqption should be caUed a sort of reasoning operaiiony more or less unconsciously and atUomaticaUy per- formed. The question seems at first a verbal one, depend- ing on how broadly the term reasoning is to be taken. If, every time a present sign suggests an absent reality to our mind, we make an inference ; and if every time we make an inference we reason ; then perception is indubitably reason- ing. Only one sees no room in it for any unconscious part. Both associates, the present sign and the contiguous things which it suggests, are above-board, and no intermediary to explain the distance of the sun from the earth, let him ask . , . 'If any- one there in the sun fired off a cannon straight at you, what should you do?* * Get out of the way ' would be the answer. • No need of that,' the toacher might reply. ' You may quietly go to sleep in your room, and get up again, you may wait till your confirmation-day, you may learn a trade, and grow as old as I am, — then only will the cannon-ball be get- ting near, then you may jump to one sidel See, so great as that is the sun's distance!*" (K. Lange, Ueber Apperception, 1879, p. 76— a charming though prolix little work.) ♦ A. Schopenhauer, Satz vom Grunde, chap iv. H. Spencer. Psychol., part VI. chaps, ix, x. E. v. Hartmann. Phil, of the Unconscious (B), chaps. VII, vin. W. Wundt. Beitrftge, pp. 422 ff.; Vorlesungen, iv, xin. H. Helmholtz. Physiol Optik, pp. 430, 447. A. Binet, Psychol, du Rai- soxmement, chaps, in, v. Wundt and Helmholtz have more recently •recanted.' See above, vol i. p. 169 note. 112 P8TCH0L0OY. ideas are required. Most of those who have upheld the thesis in question have, however, made a more complex supposition. What they have meant is that perception is a mediate inference, and that the middle term is unconscious. When the sensation which I have called * this ' (p. 83, aufyra) is felt, they think that some process like the following runs through the mind : ' This ' is M ; but M is A ; therefore * this ' is A.* Now there seem no good grounds for supposing this additional wheelwork in the mind. The classification of ' this ' as M is itself an act of perception, and should, if all perception were inference, require a still earlier syllogism for its performance, and so backwards in itifinitum. The only extrication from this coil would be to represent the process in altered guise, thus : *This' is like those; Those are A ; Therefore * this ' is A. The major premise here involves no association by conti- guity, no naming of those as M, but only a suggestion of unnamed similar images, a recall of analogous past sensa- tions with which the characters that make up A were habit- ually conjoined. But hers again, what grounds of fact are there for admitting this recall ? We are quite unconscious of any such images of the past. And the conception of all the forms of association as resultants of the elementary fact of habit-worn paths in the brain makes such images entirely superfluous for explaining the phenomena in point. Since the brain-process of * this,' the sign of A, has repeatedly been aroused in company with the process of the full object A, direct paths of irradiation from the one to the other must be already established. And although roundabout paths may also be possible, as from *this' to * those, and then * When not all M, but only some M, is A, when in other words, M is ' undistributed ' the conclusion is liable to error. Illusions would thus be logical fallacies, if true perceptions were valid syllogisms. They would draw false conclusions from undistributed middle terms. THE PERCEPTION OF THIN08. 113 from Hhose * to * A* (paths which would lead to practically the same conclusion as the straighter ones), jet there is no •ground whatever for assuming them to be traversed now, especially since appearances point the other way. In explicit reasoning, such paths are doubtless traversed , in perception they are in all probability closed. So far, then, from perception being a species of reasoning properly so called, both it and reasoning are co-ordinate varieties of that deeper sort of process known psychologically as the asso- ciation of ideas, and physiologically as the law of habit in the brain. To caU perception uruxynscious reasoning is thus either a usdess metaphor ^ or a positively misleading confusion between ttvo diff^erent things. One more point and we may leave the subject of Per- ception. Sir Wm. Hamilton thought that he had discovered a * great law ' which had been wholly overlooked by psycholo- gists, and which, 'simple and universal,' is this: "Knowl- edge and Feeling, — Perception and Sensation, though al- ways coexistent, are always in the inverse ratio of each other." Hamilton wrote as if perception and sensation were two coexistent elements entering into a single state of consciousness. Spencer refines upon him by coutending that they are two mutually exclusive states of conscious- ness, not two elements of a single state. If sensation be taken, as both Hamilton and Spencer mainly take it in this discussion, to mean the feeling of pleasure or pain^ there is no doubt that the law, however expressed, is true ; and that the mind which is strongly conscious of the pleasantness or painfulness of an experience is ipso facto less fitted to observe and analyze its outward cause.* Apart from pleas- ure and pain, however, the law seems but a corollary of the fact that the more concentrated a state of consciousness is, the more vivid it is. When feeling a color, or listening to a tone per «e, we get it more intensely, notice it better, than when we are aware of it merely as one among many other properties of a total object. The more diffused cerebral excitement of the perceptive state is probably incompatible * See Spencer. Psychol., ii. p. 250, note, for a physiological hypothesis to account for this fact. 114 PaTOHOLOGT. with quite 843 strong an excitement of separate parts as the sensational state comports. So we come back here to our own earlier discrimination between the perceptive and the sensational processes, and to the examples which we gave on pp. 80, 81.* HAIiIiUOINATIGNS. Between normal perception and illusion we have seen that there is no break, the jwoce»« being identically the same in both. The last illusions we considered might fairly be called hallucinations. We must now consider the false perceptions more commonly called by that name.t In or- * Here is another good example, taken from Helmholtz's Optics, p. 485: ''The sight of a man walking is a familiar spectacle to us. We peroeive it as a connected whole, and at most notice the most striking of its pecu- liarities. Strong attention is required, and a special choice of the point of view, in order to feel the perpendicular and lateral oscillations of such a walking figure. We must choose fitting points or lines in the background with which to compare the positions of its head. But if a distant walking man be looked at through an astronomical telescope (which inverts the object), what a singular hopping and rocking appearance he presents I No difliculty now in seeing the body's oscillations, and many other details of the gait. . . . But, on the other hand, its total character, whether light or clumsy, dignified or graceful, is harder to perceive than in the upright po- sition." f Illusions and hallucinations must both be distinguished from Mution; A delusion is a false opinion about a matter of fact, which need not neces- sarily involve, though it often docs involve, false perceptions of sensible things. We may, for example, have religious delusions, medical delusions, delusions about our own importance, about other peoples' characters, etc., ad libitum. The delusions of the insane are apt to affect certain t3rpical forms, often very hard to explain. But in many cases they are certainly theories which the patients invent to account for their abnormal bodily sensations. In other cases they are due to hallucinations of hearing and of sight. Dr. Clouston (Clinical Lectures on Mental Disease, lecture ni ad fin.) gives the following special delusions as having been found in about a hundred melancholy female patients who were afilicted in this way. There were delusions of general persecution; being destitute: generul suspicion; being followed by the police; being poisoned; being very wicked; being killed: impending death; being conspired against; impending calamity; being defrauded; the soul being lost; being preached against in church; having no stomach; being pregnant; having no inside; TRB PERCBPTION OF THIN08. IIB dinary parlance hallucination is held to differ from illusion in that, whilst there is an object really there in illusion, inhaUv^ cination there is no objective atimvlua at oH. We shall presently see that this supposed absence of objective stimulus ill hal- lucination is a mistake, and that hallucinations are often only extremes of the perception process, in which the secon* dary cerebral reaction is out of all normal proportion to the peripheral stimulus wh^ch occasions the activity. Hallu- cinations usually appear abruptly and have the character of being forced upon the subject But they possess various degrees of apparent objectivity. One mistake in limine must be guarded against They are often talked of as mental images projected outwards by mistake. But where an hallu- cination is complete, it is much more than a mental image. An hallucination is a stricUy sensational form of oonsdousnesSf as good and true a sensation as if there were a real object there. The object happens not to be there, that is alL The milder degrees of hallucination have been desig* nated as pseudo-haUtidnations. Pseudo-hallucinations and hallucinations have been sharply distinguished from eaoh having a bone in the throat; having neither stomach nor bnins; having lost much money; being covered with vermin; being unfit to live; letters being written about her; that she will not recover; property being stolen; that she is to be murdered; her children being killed; that she is to be boiled aUve; having committed theft; that she is to be starved; the legs being made of glass; that the flesh is boiling; having horns on the head; that the head is severed from the being chloroformed; body; having committed murder; that children are burning; fear of being hanged; that murders take place aromid; being called names by person ; that it is wrong to take food; being acted on by spirits; beiHg in bell; being a man; being tempted of the devil; the body being transformed; being possessed of the devil; insects coming from the bod^ having committed an unpardon- rape being practised on her; able sin; having a venereal disease; unseen agencies workiiig; being a fish; her own identity; being dead; being on fire; having committed 'suicide of the soul. 116 PSYCHOLOGY. other only within a few years. Dr. Eandinsky writes of their di£ference as follows : '^ In carelessly questioning a patient we may confound his pseudo- hallucinatory perceptions with hallucinations. But to the unconfused consciousness of the patient himself, even though he be imbecile, the identification of the two phenomena is impossible, at least in the sphere of vision. At the moment of having a pseudo-hallucination of sight^ the patient feels himself in an entirely different relation to this subjec- tive sensible appearance, from that in ^hich he finds himself whilst subject to a true visual hallucination. The latter is reality itself ; the former, on the contrary, remains always a subjective phenomenon which the individual commonly regards either as sent to him as a sign of God's grace, or as artificially induced by his secret persecutors . . . If he knows by his own expei-ieiice what a genuine hallucination is, it is quite impossible for hira to mistake the pseudo-hallucination for it. . . . A concrete example will make the difference clear : **Dr. N. L. . . . heard one day suddenly amongst the voices of his persecutors (* coming from a hollow space in the midst of the wall *) a rather loud voice impressively saying to him : ' Change your national allegiance.' Understanding this to mean that his only hope consisted in ceasing to be subject to the Czar of Russia, he reflected a moment what allegiance would be better, and resolved to become an English sub- ject. At the same moment he saw a pseudo-hallucinatory lion of natural size, which appeared and quickly laid its fore-paws on his Bhoulders. He had a lively feeling of these paws as a tolerably painful local pressure (complete hallucination of touch). Then the same voice from the wall said : *Now you have a lion — now you will rule,' where- upon the patient recollected that the lion was the national emblem of England. The lion appeared to L. very distinct and vivid, but he never- theless remained conscious, as he afterwards expressed it, that hesiiw the animal, not with his bodily but with his mental eyes. (After his re- covery he called analogous apparitions by the name of ' expressive-plastic ideas.') Accordingly he felt no terror, even though he felt t he contact of the claws. . . . Had the lion been a complete hallucination, the jmtient, as he himself remarked after recovery, would have felt groat fear, and very likely screamed or taken to flight. Had it been a simple image of the fancy he would not have connected it with the voices, of whose ob- jective reality he was at the time quite convinced." * From ordinary images of memory and fancy, pseudo- halhicinatious differ in being much more vivid, minute, de- *V. Eandinsky: Eritische u. Elinische Betrachtungeo imQebieted. Sinnestfluschungen (1885), p. 42. THE PERCEPTION OF THIN08, 117 tailed, steady, abrupt, and spontaneous, in the sense that all feeling of our own activity in producing them is lacking. Dr. Kandinsky had a patient who, after taking opium or haschisch, had abundant pseudo-hallucinations and hallu- cinations. As he also had strong visualizing power and was an educated physician, the three sorts of phenomena could be easily compared. Although projected outwards (usually not farther than the limit of distinctest vision, a loot or so) the pseudo-hallucinations lacked the character of objective reality which the hallucinations possessed, but, unlike the pictures of imagination, it was almost impossible to produce them at wilL Most of the * voices ' which people hear (whether they give rise to delusions or not) are pseudo- hallucinations. They are described as ^ inner ^ voices, al- though their character is entirely unlike the inner speech of the subject with himself. I know two persons who hear 8uch inner voices making unforeseen remarks whenever they grow quiet and listen for them. They are a very common incident of delusional insanity, and at last grow into vivid hallucinations. The latter are comparatively frequent oc- currences in sporadic form; and certain individuals are liable to have them often. From the results of the ' Census of Hallucinations,' which was l)egun by Edmund Gurney, it would appear that, roughly speaking, one person at least in every ten is likely to have had a vivid hallucination at some time in his life.* The following cases from healthy people will give an idea of what these hallucinations are : *'When a girl of eighteen^ I was one evening engaged in a very painful discussion with an elderly person. My distress was so great that I took up a thick ivory knitting-needle that was lying on the man- telpiece of the parlor and broke it into small pieces as I talked. In the midst of the discussion I was very wishful to know the opinion of a brother with whom I had an unusually close relationship. I turned round and saw him sitting at the further side of a centre-table, with his arms folded (an unusual position with him), but, to my dismay, I per- * See Proceedings of Soc. for Psych. Research, Dec. 1889, pp. 7, 188. The International Congress for Experimental Psychology has now charge erf the Census, and the present writer is its agent for America. 118 FBYCHOLOQT. oeired from the sarcastic expression of his mouth that he was not in sympathy with me, was not 'taking my side/ as I should then have expressed it. The surprise cooled me, and the discussion was dropped. **Some minutes after, having occasion to speak to my brother, I turned towards him, but he was gone. I inquired when he left the room, and was told that he had not been in it, which I did not believe, thinking that he had come in for a minute and had gone out without being noticed. About an hour and a half afterwards be appeared, and convinced me, with some trouble, that he had never been near the house that evening. He is still alive and well.*' Here is another case : *'One night in March 1878 or '74, I cannot recollect which year, I was attending on the sick-bed of my mother. About eight o^clock in the evening I went into the dining room to fix a cup of tea, and on turn- ing from the sideboard to the table, on the other side of the table before the fire, which was burning brightly, as was also the gas, I saw standing with his hand clasped to his side in true military fashion a soldier of about thirty years of age, with dark, piercing eyes looking directly into mine. He wore a small cap with standing feat her ; his costume was also of a soldierly style. He did not strike me as being a spirit, ghost, or anything uncanny, only a living man ; but after gazing for fully a minute I realized that it was nothing of earth, for he neither moved his eyes nor his body, and in looking closely I could see the fire beyond. I was of course startled, and yet did not run out of the room. I felt stunned. I walked out rapidly, h4)wever, and turning to the servant in the hall asked her if she saw anything. She said not. I went into my mother's room and remained talking for about an hour, but never mentioned the above subject for fear of exciUng her, and finally forgot it altogether, returning to the dining-room, still in forgetfulness of what had occurred, but repeating, as above, the turning from sideboard to table in act of preparing more tea. I looked casually towards the fire, and there I saw the soldier again. This time I was entirely alarmed, and fled from the room in haste. I called to my father, but when he came he saw nothing/* Sometimes more than one sense is affected The fol- lowing is a case : ** In response to your request to write out my experience of Oct. 80, 1886, I will inflict on you a letter. ** On the day above mentioned, Oct. 30, 1886, I was in , where I was teaching. I had performed my regular routine work for the day, and was sitting in my room working out trigonometrical for- THE PERCEPTION OF THIN08. 119 mulsB. I was expecting every day to hear of the confinement of my wife, and natoraliy my thoughts for some time had been more or less with her. She was, by the way, in B , some fifty miles from me. '' At the time, however, neither she nor the expected event was in my mind ; as I said, I was working out trigonometrical formulae, and I had been working on trigonometry the entire evening. About eleven o'clock, as I sat there buried in sines, cosines, tangents, cotangents, secants, and cosecants, I felt very distinctly upon my left shoulder a touch, and a slight shake, as if somebody had tried to attract my at- tention by other means and had failed. Without rising I turned my head, and there between me and the door stood my wife, dressed exactly as I last saw her, some five weeks before. As I turned she said : * It is a little Herman ; he has come.* Something more was said, but this is the only sentence i can recalL To make sure that I was not asleep and dreaming, I rose from the chair, pinched myself and walked toward the figure, which disappeared immediately as I rose. I can give no in- formation as to the length of time occupied by this episode, but I know I was awake, in my usual good health. The touch was very distinct, the figure was absolutely perfect, stood about three feet from the door, which was closed, and had not been opened during the evening. The sound of the voice was unmistakable, and I should have recognized it as my wife's voice even if I had not turned and had not seen the figure at all. The tone was conversational, just us if she would have said the same words had she been actually standing there. *' In regard to myself, I would say, as I have already intimated, I was in my usual good health ; I had not been sick before, nor was I after the occurrence, not so much as a headache having afflicted me. *' Shortly after the experience above described, I retired for the night and, as I usually do, slept quietly until morning. T did not speculate particularly about the strange appearance of the night before, and though I thought of it some, I did not tell anybody. The following morning I rose, not conscious of having dreamed anythinj^, but I was very firmly impressed with the idea that there was sometiiiug for meat the telegraph-office. J tried to throw off the impression, for so far as I knew there was no reason for it. Having nothing to do, I went out for a walk ; and to help tlrrow off the impression above noted. I walked away from the telegraph -office. As 1 proceeded, however, the impres- sion became a conviction, and I actually tunuMi about and went to the very place I had resolved not to visit, the telegraph -office. The first person I saw on arriving at said office was the telegraph-operator, who being on terms of intimacy with me, remarked : * Hello, i)apa, Tve got a telegram for you.' The telegram announced the birth of a boy, weighing nine pounds, and that all were doing well. Now. then, I have no theory at all about the events narrated above ; I never had any such experience before nor since ; I am no believer in spiritualism, am not in the least superstitious, know very little about * thought-transference,* 120 P8TCH0L0GT. * unconscious cerebration/ etc., etc., but I am absolutely oertain about what I have tried to relate. ** In regard to the remark which I heard, * It is a little Herman,* etc, I would add that we had previously decided to call the child, if a boy, Herman — my own name, by the way."* The hallucination sometimes carries a change of the general consciousness with it, so as to appear mor» like a sudden lapse into a dream. The following case was given me by a man of 43, who had never anything resembling it before : ** While sitting at my desk this a. m. reading a circular of the Loyal Legion a very curious thing happened to me, such as I have never ex- perienced. It was perfectly real, so real that it took some minutes to recover from. It seems to me like a direct intromission into some other world. I never had anything approaching it before save when dream- ing at night. I was wide awake, of course. But this was the feeling. I had only just sat down and become interested in the circular, when I seemed to lose myself for a minute and then found myself in the top story of a high building very white and shining and clean, with a noble window immediately at the right of where I sat. Through this window I looked out upon a marvellous reach of landscape entirely new. I never had before such a sense of infinity in nature, such superb stretches of light and color and cleanness, I know that for the space of three minutes I was entirely lost, for when I beji^an to come to, so to speak, — sitting in that other world, I debated for three or four minutes more as to which was dream and which was reality. Sitting there I got a faint sense of C ... [the town in which the writer was], away oflf and dim at first. Then I remember thinking ' Why, I used to live in C ; perhaps I am going back.' Slowly C did come back, and I found myself at my desk again. For a few minutes the process of determining where I was was very funny. But the whole experience was perfectly delightful, there was such a sense of brilliancy and clearness and lightness about it. I suppose it lasted in all about seven minutes or ten minutes." The hallucinations of fever-delirium are a mixture of psendo-halliicination, true hallucination, and illusion. Those of opium, hasheesh, and belladonna resemble them •This case is of the class which Mr. Myere terms 'veridical.' In a subsequent letter the writer informs me that his vision occurred some five hours brfore the child was bom. THE PERCEPTION OF THINGS, 121 in this respect. The following vivid account of a fit of hasheesh-delirium has been given me by a friend : "• I was reading a newspaper, and the indication of the approaching delirium was an inability to keep my mind fixed on the narrative. Di- rectly I lay down upon a sofa there appeared before my eyes several rows of human hands, which oscillated for a moment, revolved and then changed to spoons. The same motions were repeated, the objects chang- ing to wheels, tin soldiers, lamp-posts, brooms, and countless other absurdities. This stage lasted about ten minutes, and during that time it is safe to say that I saw at least a thousand different objects. These whirling images did not appear like the realities of life, but had the character of the secondary images seen in the eye after looking at some brightly-illuminated object. A mere suggestion from the person who was with me in the room was sufficient to call up an image of the thing suggested, while without suggestion there appeared all the com- mon objects of life and many unreal monstrosities, which it is abso- lutely impossible to describe, and which seemed to be creations of the brain. *' The character of the symptoms changed rapidly. A sort of wave seemed to pass over me, and I became aware of the fact that my pulse was beating rapidly. I took out my watch, and by exercising consider- able will-power managed to time the heart-beats, 185 to the minute. ** I could feel each pulsation through my whole system, and a curi- ous twitching commenced, which no effort of the mind could stop. " There were moments of apparent lucidity, when it seemed as if I could see within myself, and watch the pumping of my heart. A strange fear came OTcr mo, a certainty that I should never recover from the effects of the opiate, which was as quickly followed by a feeling of great interest in the experiment, a certainty that the experience was the most novel and exciting that I had ever been through. *' My mind was in an exceedingly impressionable state. Any place thought of or suggested appeared with all the distinctness of the reality. I thought of the Giant's Causeway in Staffa, and instantly I stood within the portals of Fingal's Cave. Great basaltic columns rose on all sides, while huge waves rolled through the chasm and broke in silence upon the rocky shore. Suddenly there was a roar and blast of sound, and the word * Ishmaral ^ was echoing up the cave. At the enunciation of this remarkable word the great columns of basalt changed into whirl- ing clothes pins and I laughed aloud at the absurdity. ** (I may here state that the word * Ishmaral* seemed to haunt my other hallucinations, for I remember that I heard it frequently there- after.) I next enjoyed a sort of metempsychosis. Any animal or thing that I thought of could be made the being which held my mind. I thought of a fox, and instantly I was transformed into that animal. 1 could distinctly feel myself a fox, could see my long ears and bushy 122 PSYCHOLOQy. tail, and by a sort of introvision felt that my complete anatomy was that of a fox. Suddenly the point of vision changed. My eyes seemed to be located at the back of my mouth ; I looked out between the parted lips, saw the two rows of pointed teeth, and, closing my mouth with a snap, saw— nothing. *' I was next transformed into a bombshell, felt my size, weight, and thickness, and experienced the sensation of being shot up out of a giant mortar, looking down upon the earth, bursting and falling back in a shower of iron fragments. *' Into countless other objects was I transformed, many of them so absurd that I am unable to conceive what suggested them. For ex- ample, I was a little china doll, deep down in a bottle of olive oil, next moment a stick of twisted candy, then a skeleton inclosed in a whiri- ing coffin, and so on ad ir^flnitum, '* Towards the end of the delirium the whirling images appeared again, and I was haunted by a singular creation of the brain, which re- appeared every few moments. It was an image of a double-faced doli^ with a cylindrical body running down to a point like a p^-top. ** It was always the same, having a sort of crown on its head, and painted in two colors, green and brown, on a background of blue. The expression of the Janus-like profiles was always the same, as were the adornments of the body. After recovering from the effects of the drug I could not picture to myself exactly how this singular monstros- ity appeared, but in subsequent experiences I was always visited by this phantom, and always recognized every detail of its composition. It was like visiting some long-forgotten spot and seeing some sight that had faded from the memory, but which appeared perfectly familiar aa soon as looked upon. ** The effects of the drug lasted about an hour and a half, leaving me a trifle tipsy and dizzy ; but after a ten-hour sleep I was myself again, save for a slight inability to keep my mind fixed on any piece of work for any length of time, which remained with me during most of the next day.^ THE NBUBAIi PBOCB88 IN HAIiLUOINATION. Examples of these singular perversions of perception, might be multiplied indefinitely, but I have no more space. Let us turn to the question of what the physiological pro- cess may be to which they are due. It must, of course, consist of an excitement from within of those centres which are active in normal perception, identical in kind and de- gree with that which real external objects are. usually needed to induce. The particular process which cor* THE PERCEPTION OF THINGS. 15555 rents from the sense-organs arouse would seem under normal circumstances to be arousable in no other way. On p. 72 flf. above, we saw that the centres aroused by incom- ing peripheral currents are probably identical with the centres used in mere imagination ; and that the vividness of the sensational kind of consciousness is probably cor- related with a discrete degree of intensity in the process therein aroused. Beferring the reader back to that pas- sage and to what was more lately said on p. 103 flf., I now proceed to complete my theory of the perceptive process by an analysis of what may most probably be believed to take place in hallucination strictly so called. We have seen (p. 75) that the free discharge of cells into each other through associative paths is a likely reason why the maximum intensity of function is not reached when the cells are excited by their neighbors in the cortex. At the end of Chapter XXV we sliall return to this concep- tion, and whilst making it still more precise, use it for ex- plaining certain phenomena connected with the wilL The idea is that the leakage forward along these paths is too rapid for the inner tension in any centre to accumulate to the maximal explosion-point, unless the exciting currents are greater than those which the various portions of the cortex supply to each other. Currents from the periphery are (as it seems) the only currents whose energy can van- quish the supra-ideational resistance (so to call it) of the cells, and cause the peculiarly intense sort of disintegra- tion with which the sensational quality is linked. If, hotv- every the leakage forward toere to atop, the tension inside cer- tain cells might reach the explosion-point, even though the influence which excited them came only from neighboring cortical parts. Let an empty pail with a leak in its bottom, tipped up against a support so that if it ever became full of water it would upset, represent the resting condition of the centre for a certain sort of feeling. Let water poured into it stand for the currents which are its natural stimulus ; then the hole in its bottom will, of course, represent the * paths * by which it transmits its excitement to other asso- ciated cells. Now let two other vessels have the function 124 PSYCHOLOGY. of snpplying it with water. One of these vessels stands for the neighboring cortical cells, and can pour in hardlj any more water than goes out by the leak. The pail conse- sequently never upsets in consequence of the supply from this source. A current of water passes through it and does work elsewhere, but in the pail itself nothing but what stands for ideatiorud activity is aroused. The other vessel, however, stands for the peripheral sense-organs, and sup- plies a stream of water so copious that the pail promptiy fills up in spite of the leak, and presently upsets ; in other words, sensational activity is aroused. But it is obvious that if the leak were plugged, the slower stream of supply would also end by upsetting the pail. To apply this to the brain and to thought, if we take a series of processes ABODE, associated together in that order, and suppose that the current through them is very fluent, there will be little intensity anywhere until, perhaps, a pause occurs at E. But the moment the current is blocked anywhere, say between C and D, the process in C must grow more intense, and might even be conceived to explode so as to produce a sensation in the mind instead of an idea. It would seem that some hallucinations are best to be explained in this way. We have in fact a regular series of facts which can all be formulated under the single law that ^Ae .substantive strength of a state of consciousness hears an inverse proportion to its svggestiveness. It is the halting-places ot our thought which are occupied with distinct imagery. Most of the words we utter have no time to awaken images at all ; they simply awaken the following worda But when the sentence stops, an image dwells for awhile before the , mental eye (see Vol. I. p. 243). Again, whenever the asso- ciative processes are reduced and impeded by the approach of unconsciousness, as in falling asleep, or growing faint, or becoming narcotized, we find a concomitant increase in the intensity of whatever partial consciousness may survive. In some people what M. Maury has called * hypnagogic ' hal- lucinations * are the regular concomitant of the process of *Le Sommeil et les Rdves (1865), chaps, m, iv. THE PERCEPTION OF THINOa. 126 falling asleep. Trains of faces, landscapes, etc., pass before the mental eye, first as fancies, thien as pseudo-hallucina- tions, finally as fuU-fiedged hallucinations forming dreams. If we regard association-paths as paths of drainage, then the shutting off of one after another of them as the encroaching cerebral paralysis advances ought to act like the plugging cf the hole in the bottom of the pail, and make the activity more intense in those systems of cells that retain any activity at all. The level rises because the currents are not drained away, until at last the full sensational explosion may occur. The usual explanation of hypnagogic hallucinations is that they are ideas deprived of their ordinary reductives. In somnolescence, sensations being extinct, the mind, it is said, then having no stronger things to compare its ideas with, ascribes to these the falness of reality. At ordinary times the objects of our imagination are reduced to the status of subjective facts by the ever-present contrast of our sensa- tions with them. Eliminate the sensations, however, this view supposes, and the * images ' are forthwith * projected ' into the outer world and appear as realities. Thus is the illusion of dreams also explained. This, indeed, after a fashion gives an account of the facts.* And yet it certainly fails to explain the extraordinary vivacity and completeness of so many of our dream-fantasms. The process of * imagin- ing ' must (in these cases at least f) be not merely relatively, but absolutely and in itself more intense than at other times. The fact is, it is not a process of imagining, but a genuine sensational process ; and the theory in question is therefore false as far as that point is concerned. Dr. Hugh]in£cs Jackson's explanation of the epileptic seizure is acknowledged to be masterly. It involves ♦This theory of incomplete rectification of the inner images by their usual reductives is most brilliantly stated by M. Taine in bis work on Intelligence, book ii. chap. i. t Not, of course, in all cases, because the cells remaining active are them- selves on the way to be overpowered by the general (unknown) condition to which sleep is due. 126 P8TCH0L0QT. principles exactly like those which I am bringing forward here. The * loss of cons'ciousness ' in epilepsy is due to the most highly organized brain-processes being exhausted and thrown out of gear. The less organized (more instinc- tive) processes, ordinarily inhibited by the others, are then exalted, so that we get as a mere consequence of relief from the inhibition, the meaningless or maniacal action which so often follows the attack. * Similarly the svbavUua tendinorum or jerking of the muscles which so often startles us when we are on the point * For a full account of Jackson's theories, sec his ' Croonian Lectures ' published in the Brit. Med. Jouin. for 1884. Of. also his remarks in the Discussion of Dr. Mercier's paper on Inhibition in 'Brain/ xi. 861. The loss of vivacity in the images in the process of waking, as well as the gain of it in falling asleep, are both well described by M. Taine, who writes (oii Intelligence, i. 50. 58) that often in the da3rtime, when fatigued and seated in a chair, it is sufficient for him to close one eye with a hand- kerchief, when, **by degrees, the sight of the other eye becomes vague, and it closes. All external sensations are gradually effaced, or cease, at all events, to be remarked ; the internal images, on the other band, feeble and rapid during the state of complete wakefulness, become intense, distinct, colored, steady, and lasting : there is a sort of ecstasy, accompanied by a feeling of expansion and of comfort. Warned by frequent experience, I know that sleep is coming on. and that I must not disturb the rising vision ; 1 remain passive, and in a few minutes it is complete. Architecture, landscapes, moving figures, pass slowly by, and sometimes remain, with incomparable clearness of form and fulness of being ; sleep comes on, and I know no more of the real world I am in. 3Iany times, like M. Maury, I have caused myself to be gently roused at different moments of this state, and have thus been able to mark its characters. — The intense image which seems an external object is but a more forcible continuation of the feeble image which an instant before I recognized as internal : some scrap of a forest, some house, some person which I vaguely "imagined on closing my eyes, has in a minute become present to me with full bodily details, so as to change into a complete hallucination. Then, waking up on a hand touch- ing me, I feel the figure decay, lose color, and evaporate : what had ap- peared a substance is reduced ton shadow, . . . In such a cose. I have often seen, for a passing moment, the image grow pale, waste away, and evapo- rate ; sometimes, on opening the eyes, a fragment of landscape or the skirt of a dress appears still to float over the fire-irons or on the black hearth." This persistence of dream -objects for a few moments after the eyes are opened seems to be no extremely rare experience. Many cases of it have been reported to me directly. Compare MtlUer's Physiology, Baly's tr., p. 945. THE PERCEPTION OF THIN08. 127 of failing asleep, may be interpreted as due to the rise (in certain lower motor centres) of the ordinary * tonic ' tension to the explosion-point, when the inhibition commonly ex- erted by the higher centres falls too suddenly away. One possible condition of hallucination then stands revealed, whatever other conditions there may be. When the normal paths of association bettoeen a centre and other centres are throian out of gear^ any activity which may exist in the first centre tends to increase in intensity untUfinaRy the point may be reached at which the last inward resistance is overcorne^ and the/uU sensational process explodes,* Thus it will happen that causes of an amount of activity in brain-cells which would ordinarily result in a weak consciousness may pro- duce a very strong consciousness when the overflow of these cells is stopped by the torpor of the rest of the brain. A sUght peripheral irritation, then, if it reaches the centres of •consciousness at all during sleep, will give rise to the dream of a violent sensation. All the books about dreaming are full of anecdotes which illustrate this. For example, M. Maury's nose and lips are tickled with a feather while he sleeps. He dreams he is beiug tortured by having a pitch- plaster applied to his face, torn off, lacerating the skin of nose and lips. Descartes, on being bitten by a flea, dreams of being run through by a sword. A friend tells me, as I write this, of his hair changing its position in his forehead just as he * dozed off' in his chair a few days since. In- stantly he dreamed that some one had struck him a blow. Examples can be quoted ad libitum, but these are enough, t * I say the ' normal ' paths, because halluciDations are Dot iDCompatible with some paths of association beiug left. Some hypnotic patients will not only have hallucinations of objects suggested to them, but will amplify them and act out the situation. But the paths here seem excessively nar- row, and the reflections which ought to make the hallucination incredible do not occur to the subject's mind. In general, the narrower a train of * ideas ' is, the vivider the consciousness is of each. Under ordinary cir- cumstances, the entire brain probably plays a part in draining any centre which may be ideationally active. When the drainage is reduced in any way it probably makes the active process more intense. f M. A. Maury gives a number: op. cit. pp. 1S6-S. 128 P8TCH0L0OT, We seem herewith to have an explanation for a certain number of hallucinations. Whenever the normal forward irradiation of irvtra-cortical excitement through association-paihs is checked, any accidental spontaneous activity or any peripheral stimulation {hotvever inadequate at other times) by which a brain- centre may be visited, sets up a process off'vH sensational inten- sity therein. In the hallucinations artificially produced in hypnotic subjects, some degree of peripheral excitement seems usu- ally to be required. The brain is asleep as far as its own spontaneous thinking goes, and the words of the ' magneti- zer ' then awaken a cortical process which drafts oflf into itself any currents of a related sort which may come in from the periphery, resulting in a vivid objective percep- tion of the suggested thing. Thus, point to a dot on a sheet of paper, and call it * General Grant's photograph,*' and your subject will see a photograph of the General there instead of the dot. The dot gives objectivity to the appearance, and the suggested notion of the General gives it form. Then magnify the dot by a lens ; double it by a prism or by nudging the eyeball ; reflect it in a mirror ; turn it upside down ; or wipe it out ; and the subject will tell you that the * photograph ' has been enlarged, doubled, reflected, turned about, or made to disappear. In M. Binet's language, * the dot is the outward point de repere which is needed to give objectivity to your suggestion, and without which the latter will only produce a conception in the subject's mind.t M. Binet has shown that such a periphe- * M. Bluet's highly important experiments, which were first published in vol. XVII of the Revue Philosophique (1884), are also given in full in chapter ix of his and Fere's work on ' Animal Magnetism ' in the Inter- national Scientific Series. Where there is no dot on the paper, nor any other visible mark, the subject's judgment about the * portrait * would seem to be guided by what he sees happening to the entire sheet. t It is a difticult thing to distinguish in a hypnotic patient between a genuine sensorial hallucination of something suggested and a conception of it merely, coupled with belief that it is there. I have been surprised at the vagueness with which such subjects will oftijn trace upon blank paper the outlines of the pictures which they say they * see ' thereupon. On the other THB PBRCBPTION OF THING8. 1S» ral point de rqph^ is used in an enormous number, not only of hypnotic hallucinations^ but of hallucinations of the insane. These latter are of ten t^niZo^oZ ; that is, the patient hears the voices always on one side of him, or sees the figure only when a certain one of his eyes is open. In many of these cases it has been distinctly proved that a morbid irritation in the internal ear, or an opacity in the humors of the eye, was the starting point of the current which the patient's diseased acoustic or optical centres clothed with their peculiar products in the way of ideas. Hallucinations prodvced in this way are 'illusions '; and M. Binet'a theory, that all haUvcinationa must start in the periphery, may be called an attempt to reduce hallucination and illusion to one physiological type, the type, namely, to which normal per- ception belongs. In every case, according to M. Binet, whether of perception, of hallucination, or of illusion, we get the sensational vividness by means of a current from the peripheral nerves. It may be a mere trace of a cur- rent But that trace is enough to kindle the maximal or snpra-ideational process so that the object perceived will have the character of externality. What the nature of the object shall be will depend wholly on the particular sys- tem of paths in which the process is kindled. Part of the thing in all cases comes from the sense-organ, the rest is furnished by the mind. But we cannot by inirospection distinguish between these parts ; and our only formula for the result is that the brain has reacted on the impression in the normal way. Just so in the dreams which we haye considered, and in the hallucinations of which M. Binet tells, we can only say that the brain has reacted in an abnor- mal way. if. Binet's theory accounts indeed/or a multitude of cases.^ but certainly not for aU, The prism does not always double hand, you will bear them say that they find no difference between a real flower which you show them and an imaginary flower which you tell them is beside it. When told that one is imaginary and that they must pick out the real one, they sometimes say the choice la impossible, and sometimes they point to the imaginary flower. 180 PSTCHOWGT. the false appearance,^ nor does the latter always disappear when the eyes are closed. Dr. Hack Tuke t gives several examples in sane people of well-exteriorized hallucinations which did not respond to Binet's tests ; and Mr. Edmund Gurney % gives a number of reasons why intensity in a cor- tical process may be expected to result from local patho- logical activity just as much as its peculiar nature doea For Binet, an abnormally or exclusively active part of the cortex gives the nature of what shall appear, whilst a pe- ripheral sense-organ alone can give the intensity sufficient to make it appear projected into real space. But since this intensity is after all but a matter of degree, one does not see why, under rare conditions, the degree in question mighi not be attained by inner causes exclusively. In that case we should have certain hallucinations centrally initiated alongside of the peripherally initiated hallucinations, which are the only sort that M. Binet's theory allows. It seems probable on the whole, therefore, that centrally initiated haUu- cinations can exist. How often they do exist is another ques- tion. The existence of hallucinations which affect more than one sense is an argument for central initiation. For grant that the thing seen may have its starting point in the outer world, the voice which it is heard to utter must be due to an influence from the visual region, i.e. must be of central origin. Sporadic cases of hallucination, visiting people only once in a lifetime (which seem to be by far the most fre- quen*^^ type), are on any theory hard to understand in detail They are often extraordinarily complete ; and the fact that many of them are reported as veridical^ that is, as coincid- ing with real events, such as accidents, deaths, eta, of the persons seen, is an additional complication of the phe- nomeiion. The first really scienlitic study of hallucination * Only the other day, in three hypnotized girls, I failed to double as hallucination with a prism. Of course it may not have been a fully- developed hallucination. t Brain, xi. 441. IMind, X. 161, 816 ; and Phantasms of the Living (1886), I. 470-488. THE PERCEPTION OF THINQS. 131 iu all its possible bearings, on the basis of a large mass of empirical material, was begun bj Mr. Edmund Gumey and is continued by other members of the Society for Psy- chical Besearch ; and the * Census ' is now being applied to several countries under the auspices of the International Congress of Experimental Psychology. It is to be hoped that out of these combined labors something solid will eventually grow. The facts shade off into the phenomena of motor automatism, trance, etc.; and nothing but a wide comparative study can give really instructive results.* The part played by the peripheral sense-organ in hallucina- tion is just as obscure as we found it in the case of imagina- tion. The things seen often seem opaque and hide the background upon which they are projected. It does not foUow from this, however, that the retina is actually in- volved in the vision, A contrary process going on in the visual centres would prevent the retinal impression made by the outer realities from being felt, and this would in mental terms be equivalent to the hiding of them by the imaginary figure. The negative after-images of mental pictures reported by Meyer and F^r^, and the negative after- images of hypnotic hallucinations reported by Binet and others so far constitute the only evidence there is for the retina being involved. But until these after-images are explained in some other way we must admit the possibility of a centrifugal current from the optical centres downwards into the peripheral organ of sight, paradoxical as the course of such a current may appear. • PEBOEPTION-TIMB.' TTie time which the perceptive process occupies has been inquired into by various experimenters. Some call it per- ception-time, some choice-time, some discrimination-tima The results have been already given in Chapter XIII (voL I, p. 523 ff.), to which the reader is consequently referred. * In Mr. Guraey's work. Just cited, a very Uu^ge Dumber of veridical cases are critically discussed. 132 P8JCH0L0QT, Dr. Bomanes gives an interesting variation of these time-measurements. He found ^ ^* an astonishing difference between different individuals with respect to the rate at which they are able to read. Of course reading implies enormously intricate processes of perception both of the sensuous and of the intellectual order ; but if we choose for these observations per- sons who have been accustomed to read much, we may consider that they are all very much on a par with respect to the amount of practice which they have had, so that the differences in their rates of reading may fairly be attributed to real differences in their rates of forming complex perceptions in rapid succession, and not to any merely acci- dental differences arising from greater or less facility acquired by special practice. ** My experiments consisted in marking a brief printed paragraph in ft book which had never been read by any of the persons to whom it was to be presented. The paragraph, which contained simple state- ments of simple facts, was marked on the margin with pencil. The book was then placed before the reader open, the page, however, being covered with a sheet of paper. Having pointed out to the reader upon this sheet of paper what part of the underlying page the marked para- graph occupied, I suddenly removed the sheet of paper with one hand, while I started a chronograph with the other. Twenty seconds being allowed for reading the paragraph (ten lines octavo), as soon as the time was up I again suddenly placed the sheet of paper over the printed page, passed the book on to the next reader, and repeated the experi- ment as before. Meanwhile, the first reader, the moment after the book had been removed, wrote down all that he or she could remember having read. And so on with all the other readers. **Now the results of a number of experiments conducted on this method were to show, as I have said, astonishing differences in the maximum rate of reading which is possible to different individuals, all of whom have been accustomed to extensive reading. That is to say, the difference may amount to 4 to 1 ; or, otherwise stated, in a given time one individual may be able to read four times as much as another. Moreover, it appeared that there was no relationship between slowness of reading and power of assimilation ; on the contrary, when all the efforts are directed to assimilating as much as possible in a given time, the rapid readers (as shown by their written notes) usually give a bet- ter account of the portions of the paragraph which have been com- passed by the slow readers than the latter are able to give ; and the most rapid reader I have found is also the best at assimilating. I should further say that there is no relationship between rapidity of perception as thus tested and int^illectual activity as tested by the gen- eral results of intellectual work ; for I have tried the experiment with * Mental £volution in Animals, p. 186. THE PEBOBPTION OF THIN08. 133 aeveral highly distinguished men in science and literature, most of whom I found to be slow readers." * *LUercUure, The best treatment of perception with which lam ac- quainted is that in Mr. James Sully's book on ' Illusions ' in the Interna- tional Scientific Series. On hallucinations the literature is large. Oumey, Eandinsky (as already cited), and some articles by Eraepelin in the Vierteljahrschrift ftlr Wissenschaftliche Philoeophie, vol. T (1881), are the most systematic studies recently made. All works on Insanity treat of them. Dr. W. W. Ireland's works. ' The Blot upon the Brain ' (1886) and * Through the Ivory (3ate ' (1890) have much information on the subject. Gumey gives pretty complete references to older literature. The most important thing on the subject from the point of view of theoiy Is the article by Mr. Myers on the Demon of Socrates in the Proceedings of tha Society for I^chical Research for 1880. p. Sdd. CHAPTEE XX THE PERCEPTION OF SPACE.* THE FEELINO OF CBTTDE EXTEN8ITY. In the sensations of hearing, touch, sight, .and pain toe are accustomed to distinguish from among the other elements the dement of vduminou^sness. We call the reverberations of a thuuderstorm more voluminous than the squeaking of a slate-pencil ; the entrance into a warm bath gives our skin a more massive feeling than the prick of a pin; a little neuralgic pain, line as a cobweb, in the face, seems less ex- tensive than the heavy soreness of a boil or the vast discom- fort of a colic or a lumbago ; and a solitary star looks smaller than the noonday sky. In the sensation of dizziness or subjective motion, which recent investigation has proved to be connected with stimulation of the semi-circular canals of the ear, the spatial character is very prominent Whether the * muscular sense * directly yields us knowledge of space is still a matter of litigation among psychologists. Whilst some go so far as to ascribe our entire cognition of exten- sion to its exclusive aid, others deny to it all extensive quality whatever. Under these circumstances we shall do better to adjourn its consideration ; admitting, however, that it seems at first sight as if we felt something decidedly more voluminous when we contract our thigh-muscles than when we twitch an eyelid or some small muscle in the face. It seems, moreover, as if this difierence lay in the feeling of the thigh-muscles themselves. In the sensations of smell and taste this element of varying vastness seems less prominent but not altogether absent Some tastes and smells appear less extensive than complex flavors, like that of roast meat or plum pudding, on the one hand, or heavy odors like musk or tuberose, on * Reprinted, with considerable revision, from * Mind ' for 1887. 184 THB PEROEPTION OF 8PA0B. 136 the other. The epithet sharp given to the acid class would seem to show that to the popular mind there is something narrow and, as it were, streaky, in the impression they make, other flavors and odors being bigger and rounder. The sensations derived from the inward organs are also distinctly more or less voluminous. Bepletion and empti- ness, suffocation, palpitation, headache, are examples of this, and certainly not less spatial is the consciousness we have of our general bodily condition in nausea, fever, heavy drowsiness, and fatigi^e. Our entire cubic content seems then sensibly manifest to us as such, and feels much larger than any local pulsation, pressure, or discomfort. Skin and retina are, however, the organs in which the space- element plays the most active part. Not only does the maximal vastness yielded by the retina surpass that yielded by any other organ, but the intricacy with which our atten- tion can subdivide this vastness and perceive it to be com- posed of lesser portions simultaneously coexisting along- side of each other is without a parallel elsewhere.* The ear gives a greater vastness than the skin, but is consider- ably less able to subdivide iit Now my first thesis is that this element, discernible in each and every sensation, though more developed in some than in others, is the original sensation of space, out of which all the exact knowledge about space that we afterwards come to have is woven by processes of discrimination, association, and selection. * Extensity,' as Mr. James Ward calls it,:|: * Prof. Jastrow has found thai invariably we tend to underestimate the amount of our skin which may be stimulated by contact with an object when we express it in terms of visual space; tliat is, when asked to mark on paper the extent of skin affected, we always draw it much too small. This shows that the eye gets as much space feeling from the smaller line as the skin gets from the larger one. Cf. Jastrow ; Mind, xi. 546-7; Ameri- can Journal of Psychology, m. 53. f Amongst sounds the graver ones seem the most extensive, Stumpf gives three reasons for this: 1) association with bigger causes; 2) wider reverberation of the hand and body when grave notes are sung; 8) audi- bility at a greater distance. He thinks that these three reasons dispense us from supposing an immanent extensity in the sensation of sound as such. See his remarks in the Tonpsychologie, i. 207-211. \ Encyclopaedia Britannica, 9th Edition, article Psychology, pp. 46, 58. 136 P8TGH0L0QT. on this view, becomes an element in each sensation just as intensity is. The latter every one will admit to be a dis- tinguishable though not separable ingredient of the sensible quality. In like manner extensity, being an entirely pecul- iar kind of feeling indescribable except in terms of itself, and inseparable in actual experience from some sensational quality which it must accompany, can itself receive no other name than that of senaaiiorud dement. It must now be noted that the vaatneaa hitherto spoken (^ is cts great in one direction as in another. Its dimensions are so vague that in it there is no question as yet of surface as opposed to depth ; ' volume ' being the best short name for the sensation in question. Sensations of different orders are roughly comparable^ inter se, unth respect to their volumes. This shows that the spatial quality in each is identical wherever found, for diflferent qualitative elements, e.g. warmth and odor, are incommensurate. Persons bom blind are reported surprised at the largeness with which objects appear to them when their sight is restored. Franz says of his patient cured of cataract : "He saw ever3rthing much larger than he had supposed from the idea obtained by his sense of touch. Moving, and especially living, objects appeared very large." * Loud sounds have a cer- tain enormousness of feeling. It is impossible to conceive of the explosion of a cannon as filling a small space. In general, sounds seem to occupy all the room between us and their source ; and in the case of certain ones, the cricket's song, the whistling of the wind, the roaring of the surf, or a distant railway train, to have no definite start- ing point. In the sphere of vision we have facts of the same order. 'Glowing' bodies, as Hering says, give us a perception ** which seems roomy (raumha/t) in comparison with that of strictly surface color. A glowing iron looks luminous through and through, and so does a flame." t A luminous fog, a band of sunshine, affect us in the same way. As Hering urges : * Philosophical Trausactions (1841). t Hermann's Hnndb d. Physiol., Bd iii. 1, S 575. THE PERCEPTION OF SPACE, 137 *' We must distinguish roomy from superficial, as well as distinctly from indistinctly bounded, sensations. The dark which with closed eyes one sees before one is, for example, a roomy sensation. We do not see a black surface like a wall in front of us, but a space filled with dark- ness, and even when we succeed in seeing this darkness as terminated by a black wall there still remains in front of this wall the dark space. The same thing happens when we find ourselves with open eyes in an absolutely dark room. This sensation of darkness is also vaguely bounded. An example of a distinctly bounded roomy sensation is that of a clear and colored fluid seen in a glass ; the yellow of the wine is seen not only on the bounding surface of the glass ; the yellow sensa- tion fills the whole interior of the glass. By day the so-called empty space between us and objects seen appears very different from what it is by night. The increasing darkness settles not only upon the things but also between us and the things, so as at last to cover them com- pletely and fill the space alone. If I look into a dark box I find it filled with darkness, and this is seen not merely as the dark-colored sides or walls of the box. A shady corner in an otherwise well-lighted room is full of a darkness which is not only on the walls and fioor but between them in the space they include. Every sensation is there where I ex- perience it, and if I have it at once at every point of a certain roomy space, it is then a voluminous sensation. A cube of transparent green glass gives us a spatial sensation : an opaque cube painted green, on the contrary, only sensations of surface."* There are certain quasi-motor sensations in the head when we change the direction of the attention, which equally seem to involve three dimensions. If with closed eyes we think of the top of the house and then of the cellar, of the distance in front of us and then of that behind us, of space far to the right and then far to the left, we have something far stronger than an idea, — an actual feeling, namely, as if something in the head moved into another direction. Fechner was, I believe, the first to publish any remarks on these feelings. He writes as follows : " When we transfer the jitteiition from objects of one sense to those of another we have an indescribable feeling (though at the same time one perfectly determinate and reproducible at pleasure) of altered direc- tion, or differently localized tension (Spannung), We feel a strain for- ward in the eyes, one directed sideways in the ears, increasing with the degree of our attention, and changing according as we look at an object carefully, or listen to something attentively ; wherefore we speak of straining the attention. The difference is most plainly felt when ♦ Lac. ciU 8. 572. 138 P8TCH0L0OT. the attention vibrates rapidly between eye and ear. This feeling local* izes itself with most decided difference in regard to the varions sense- organs according as we wish to discriminate a thing delicately by touchy taste, or smell. '* But now I have, when I try to vividly recall a picture of memory or fancy, a feeling perfectly analogous to that which I experience when I seek to grasp a thing keenly by eye or ear ; and this analogous feeling is very differently localized. While in sharpest possible attention to real objects (as well as to after-images) the strain is plainly forwards, and, when the attention changes from one sense to another, only alters its direction between the sense-organs, leaving the rest of the head free from strain, the case is different in memory or fancy ; for here the feel- ing withdraws entirely from the external sense-organs, and seems rather to take refuge in that part of the head which the brain fills. If I wish, for example, to recall a place or person, it will arise before me with vividness, not according as I strain my attention forwards, but rather in proportion as I, so to speak, retract it backwards.*** It appears probable that the feelings which Fechner de- scribes are in part constituted by imaginary semi-circular canal sensations, t These undoubtedly convey the most delicate perception of change in direction ; and when, as here, the changes are not perceived as taking place in the external world, they occupy a vague internal space located within the head. J * Elemente der Psyebophysik, ii. 475-6. t See Foster's Text-book of Physiology, bk. in. c. vi. § 2. X Fechner, who was ignorant of the but lately discovered function of the semi-circular canals, gives a diifcrent explanation of the organic seat of these feelings. They are probably highly composite. With me, actual move- ments in the eyes play a considerable part in them, though I am hardly con- scious of tbe peculiar feelings in the scalp which Fechner goes on to de- scribe thus : ' ' The feeling of strained attention in the different sense-organs seems to be only a muscular one produced in using these various organs by setting in motion, by a sort of reflex action, the set of muscles which belong to them. One can ask, then, with what particular muscular con- traction the sense of strained attention in the effort to recall something is associated ? On this cjuestion my own feeling gives me a decided answer ; it comes to me distin(;tly not as a sensation of tension in the inside of the head, but as a feeling of strain and contraction in the scalp, with a pressure from outwards in over the whole cranium, undoubtedly caused by a con- traction of the muscles of the scalp. This harmonizes very well with the expressions, sich den Kopf zerbrechen, den Kopf zusammennehmen. In a former illness, when I could not endure the slightest effort after continuous thought, and had no theoretical bins on this question, the muscles of the scalp, especially those of the back-head, assumed a fairly morbid degree of sensibility whenever I tried to think." (Elem. der Psychophysik, ii. 490-91.) TEE PEROEPTION OF 8PA0E. 139 In the still itself there is a vague form of projection into the third dimension to which Hering has called atten- tion. ** Heat is not felt only against the cutaneous surface, but when com- municated through the air may appear extending more or less out from the surface into the third dimension of surrounding space. . . . We can determine in the dark the place of a radiant body by moving the hand to and fro, and attending to the fluctuation of our feeling of warmth. The feeling itself, however, is not projected fully into the spot at which we localize the hot body, but always remains in the neighborhood of the hand." The interior of one's mouth-cavity feels larger when ex- plored by the tongue than when looked at. The crater of a newly-extracted tooth, and the movements of a loose tooth in its socket,, feel quite monstrous. A midge buzzing against the drum of the ear will often seem as big as a but- terfly. The spatial sensibility of the tympanic membrane has hitherto been very little studied, though the subject will well repay much trouble. If we approach it by intro- ducing into the outer ear some small object like the tip of a roUed-up tissue-paper lamplighter, we are surprised at the large radiating sensation which its presence gives us, and at the sense of clearness and openness which comes when it is removed. It is immaterial to inquire whether the far-reaching sensation here be due to actual irradiation upon distant nerves or noi We are considering now, not the objective causes of the spatial feeling, but its subjective varieties, and the experiment shows that the same object gives more of it to the inner than to the outer cuticle of the ear. The pressure of the air in the tympanic cavity upon the membrane gives an astonishingly large sensation. We can increase the pressure by holding our nostrils and closing our mouth and forcing air through our Eustachian tubes by an expiratory efi'ort ; and we can diminish it by either inspiring or swallowing under the same conditions of closed mouth and nose. In either case Wf3 get a large round tridimensional sensation inside of the head, which seems as if it must come from the affection of an organ much larger than the tympanic membrane, whose surface hardly exceeds that of one's little-finger-nail. 140 PSTCffOLOQT. The tympanic membrane is furthermore at)le to render sensible differences in the pressure of the external atmos- phere, too slight to be felt either as noise or in this more yiolent way. If the reader will sit with closed eyes and let a friend approximate some solid object, like a large book, noiselessly to his face, he will immediately become aware of the object's presence and position — likewise of its de- parture. A friend of the writer, making the experiment for the first time, discriminated unhesitatingly between the three degrees of solidity of a board, a lattice-frame, and a sieve, held close to his ear. Now as this sensation is never used by ordinary persons as a means of perception, we may fairly assume that its felt quality, in those whose attention is called to it for the first time, belongs to it qnd sensation, and owes nothing to educational suggestions. But this felt quality is most distinctly and unmistakably one of vague spatial vastness in three dimensions — quite as much so as is the felt quality of the retinal sensation when we lie on our back and fill the entire field of vision with the empty blue sky. When an object is brought near the ear we im- mediately feel shut in, contracted; when the object is removed, we suddenly feel as if a transparency, clearness, openness, had been made outside of us. And the feeling will, by any one who will take the pains to observe it, be acknowledged to involve the third dimension in a vague, unmeasured state.* The reader will have noticed, in this enumeration of facts, that voluminousness of the feeling seems to bear very little relation to the size of the organ that yields it. The ear and eye are comparatively minute organs, yet they give us feel- ings of great volume. The same lack of exact proportion between size of feeling and size of organ affected obtains within the limits of particular sensory organs. An object appears smaller on the lateral portions of the retina than it does on the fovea, as may be easily verified by holding the * That the sensatioD in question is one of tactile rather than of acoustic sensibility would seem proved by the fact that a medical friend of the writer, both of whose membrana tymjHini are quite normal, but one of whose ears is almost totally deaf, feels the presence and withdrawal of ob- jects as well at one ear as at the other. THE PEROEPTION OF SPACE. 141 two forefingers parallel and a couple of inches apart, and transferring the gaze of one eye from one to the other. Then the finger not directly looked at will appear to shrink, and this whatever be the direction of the fingers. On the tongue a crumb, or the calibre of a small tube, appears larger than between the fingers. If two points kept equi- distant (blunted compass- or scissors-points, for example) be drawn across the skin so as really to describe a pair of parallel lines, the lines will appear farther apart in some spots than in others. If, for example, we draw them hori- zontally across the face, so that the mouth falls between them, the person experimented upon will feel as if they began to diverge near the mouth and to include it in a well- marked ellipse. In like manner, if we keep the compass- Fio. 61 (after Weber). points one or two centimetres apart, and draw them down the forearm over the wrist and palm, finally drawing one along one finger, the other along its neighbor, the appear- ance will be that of a single line, soon breaking into two, which become more widely separated below the wrist, to contract again in the palm, and finally diverge rapidly again towards the finger-tips. The dotted lines in Figs. 51 and 52 represent the true path of the compass-points ; the full lines their apparent path. The same length of skin, moreover, will convey a more extensive sensation according to the manner of stimulation. If the edge of a card be pressed against the skin, the dis- tance between its extremities will seem shorter than that be- tween two compass-tips touching the same terminal points.* * The skin seems to obey a different law from the eye here. If a given retinal tract be excited, first by a series of points, an4 next by the two 142 PSTCHOLOOT, In the eye, intensity of nerve-stimulation seems to in- crease the vdume of the feeling as well as its brilliancy. If we raise and lower the gas alternately, the whole room and all the objects in it seem alternately to enlarge and contract If we cover half a page of small print with a gray glass, the print seen through the glass appears decidedly smaller than that seen outside of it, and the darker the glass the greater the difference. When a circumscribed opacity in front of the retina keeps off part of the light from the portion which it covers, objects projected on that portion may seem but half as large as when their image falls outside of it* The inverse effect seems produced by certain drugs and anaesthetics. Mor- phine, atropine, daturine, and cold blunt the sensibility of the skin, so that dis- tances upon it seem less. Haschish pro- duces strange perversions of the general sensibility. Under its influence one's body may seem either enormously en- larged or strangely contracted. Some- times a single member will alter its proportion to the rest; or one's back, for instance, will appear entirely absent, as if one were hollow behind. Objects comparatively near will recede to a vast distance, a short street assume to the eye an immeasurable perspective. Ether and chloroform I Fio. 62 (after Weber). extreme points, with the interval between them unexcited, this interval will seem considerably less in the second case than it seemed in the first. In the skin the unexcited interval feels the larger. The reader may easily verify the facts in this case by taking a visiting-card, cutting one edge of it into a saw-tooth pattern, and from the opposite edge cutting out all but the two comers, and then comparing the feelings aroused by the two edges when held against the skin. * Classen, Physiologic des tresichtssinnes, p. 114 ; see also A. Riehl, Der Philosophische Kriticismus, ii. p. 149. THE PERCEPTION OF SPACE, 143 occaaionally produce not wholly dissimilar results. Panum, the German physiologist, relates that when, as a boy, he was etherized for neuralgia, the objects in the room grew extremely small and distant, before his field of vision dark- ened over and the roaring in his ears began. He also men- tions that a Mend of his in church, struggling in vain to keep awake, saw the preacher grow smaller and smaller and more and more distant I myself on one occasion observed the same recession of objects during the begin- ning of chloroformization. In various cerebral diseases we find analogous disturbances. Can ive assign the physiological conditions which make ths elementary sensible largeness of one sensation vary so much from that of another ? Only imperfectly. One factor in the re- sult undoubtedly is the number of nerve-terminations simultaneously excited by the outward agent that awakens the sensation. When many skin-nerves are warmed, or much retinal surface illuminated, our feeling is larger than when a lesser nervous surface is excited. The single sen- sation yielded by two compass-points, although it seems simple, is yet felt to be much bigger and blunter than that yielded by one. The touch of a single point may always be recognized by its quality of sharpness. This page looks much smaller to the reader if he closes one eye than if both eyes are open. So does the moon, which latter fact shows that the phenomenon has nothing to do with parallax. The celebrated boy couched for the cataract by Cheselden thought, after his first eye was operated, " all things he saw extremely large," but being couched of his second eye, said " that objects at first appeared large to this eye, but not so large as they did at first to the other ; and looking upon the same object with both eyes, he thought it looked about twice as large as with the first couched eye only, but not double, that we can anyways discover." The greater extensiveness that the feeling of certain parts of the same surface has over other parts, and that one order of surface has over another (retina over skin, for example), may also to a certain extent be explained by the operation of the same factor. It is an anatomical fact that the most spatially sensitive surfaces (retina, tongue, finger- 144 PaTGHOLOQT. tips, etc.) are supplied by nerve-trunks of unusual thick- ness, which must supply to every unit of surface-area an unusually large number of terminal fibres. But the varia- tions of felt extension obey probably only a very rough law of numerical proportion to the number of fibres, A sound is not twice as voluminous to two ears as to one ; and the above-cited variations of feeling, when the same surface is excited under different conditions, show that the feeling is a resultant of several factors of which the anatomical one is only the principal. Many ingenious hypotheses have been brought forward to assign the co-operating factors where different conditions give conflicting amounts of felt space. Later we shall analyze some of these cases in de- tail, but it must be confessed here in advance that many of them resist analysis altogether. * * It is worth while at this point to call attention with some emphasis to the fact that, though the anatomical condition of the feeling reiemble» the feeling itself, such resemblance cannot be taken by our understanding to explain why the feeling should be just what it is. We hear it untiringly reiterated by materialists and spiritualists alike that we can see no possible inward reason why a certain brain-process should produce the feeling of redness and another of anger : the one process is no more red than the other is angry, and the coupling of process and feeling is, as far as our understanding goes, a juxtaposition pure and simple. But in the matter of ipatial feeling, where the retinal patch that produces a triangle in the mind is itself a triangle, etc., it looks at first sight as if the sensation might be a direct cognition of its own neural condition. Were this true, however, our sensation should be one of multitude rather than of continuous extent ; for the condition is number of optical nerve-termini, and even this is only a remote condition and not an immediate condition. The immediate condi- tion of the feeling is not the process in the retina, but the process in the brain; and the process in the brain may, for aught we know, be as unlike a triangle, — nay, it probably is so, — as it is unlike redness or rage. It is simply a coincidence iheii in the case of space one of the organic conditions, viz. , the triangle impressed on the skin or the retina, should lead to a rep- resentation in the mind of the subject observed similar to that which it produces in the psychological observer. In no other kind of case is the coincidence found. Even should we admit that we cognize triangles in space because of our immediate cognition of the triangular shape of our excited group of nerve-tips, the matter would hardly be more transparent, for the mysteiy would still remain, why are we so much better cognizant of triangles on our finger-tips than on the nerve-tips of our back, on our eye than on our ear, and on any of these parts than in our brain ? Thos. Brown very rightly rejects the notion of explaining the shape of the space perceived by the shape of the 'nervous expansion affected.' "If this THE PERCEPTION OF SPACE, 145 TETE PEIBOIIPTION OF SPATTATi OBDBB. So far, all we have established or sought to establish is the existence of the vague form or quale of spatiality as an inseparable element bound up with the other peculiarities of each and every one of our sensations. The numerous examples we have adduced of the variations of this extensive element have only been meant to make clear its strictly sensational character. In very few of them will the reader have been able to explain the variation by an added intel- lectual element, such as the suggestion of a recollected ex- perience. In almost all it has seemed to be the immediate psychic e£fect of a peculiar sort of nerve-process excited ; and all the nerve-processes in question agree in yielding what space they do yield, to the mind, in the shape of a simple total vastness, in which, primitively at least, no order of parts or of svbdivisions reigns. Let no one be surprised at this notion of a space without order. There may be a space without order just as there may be an order without space.* And the primitive percep- tions of space are certainly of an unordered kind. The order which the spaces first perceived potentially include must, before being distinctly apprehended by the mind, be woven into those spaces by a rather complicated set of in- tellectual acts. The primordial largenesses which the sen- sations yield must be measured and svbdivided by conscious- ness, and added together, before they can form by their synthesis what we know as the real Space of the objective world. In these operations, imagination, association, at- tention, and selection play a decisive part ; and although they nowhere add any new material to the space-data of sense, they so shuffle and manipulate these data and hide aloDe were necessary, we should have square inches and half inches, and various other forms, rectilinear and curvilinear, of fragance and sound." (Lectures, xxii.) ♦ Musical tones, e.g., have an order of quality independent either of their space- or time-order. Music comes from the time-order of the notes upsetting their quality- order. In general, it abed efg h ij k, etc., stand for an arrangement of feelings in the order of their quality, they may as- sume cmy space-order or time-order, &8 defa h g, etc., and still the order of quality will remain fixed and unchanged. 146 PaTCHOLOGT. present ones behind imagined ones that it is no wonder if some authors have gone so far as to think that the sense- data have no spatial worth at all, and that the intellect, since it makes the subdivisions, also gives the spatial quality to them out of resources of its own. As for ourselves, having found that all our sensations (however as yet unconnected and undiscriminated) are of extensive objects, our next problem is : How do we abrangb these at first chaotically given spaces into the one regtdar and orderly * world of space' which we now know? To begin with, there is no reason to suppose that the several sense-spaces of which a sentient oreature may become conscious, each filled with its own peouliar oontent, should tend, simply because they are many, to enter into any definite spatial intercourse with each other, or lie in any particular order of positions. Even in ourselves we can recognize this. Difierent feelings may coexist in us without assuming any particular spatial order. The sound of the brook near which I write, the odor of the cedars, the comfort with which my breakfast has filled me, and my in- terest in this paragraph, all lie distinct in my consciousness, but in no sense outside or alongside of each other. Their spaces are interfused and at most fill the same vaguely ob- jective world. Even where the qualities are far less dis- parate, we may have something similar. If we take our subjective and corporeal sensations alone, there are moments when, as we lie or sit motionless, we find it very difficult to feel distinctly the length of our back or the direction of our feet from our shoulders. By a strong effort we can succeed in dispersing our attention impartially over our whole per- son, and then we feel the real shape of our body in a sort of uuitary way. But in general a few parts are strongly emphasized to consciousness and the rest sink out of notice ; and it is then remarkable how vague and ambiguous our perception of their relative order of location is. Obviously, for the orderly arrangement of a multitude of sense-spaces in consciousness, something more than their mere separate existence is required. What is this further condition? //* a number of sensible extents are to be perceived alongside THE PEBOBPTION OF SPACE, 147 of each other and in definite order they must appear as parts in a vaster sensible extent which can enter the mind simply and aU at once. I think it will be seen that the difiSculty of esti- mating correctly the form of one's body by pure feeling arises from the fact that it is very hard to feel its totality as a unit at alL The trouble is similar to that of thinking for- wards and backwards simultaneously. When conscious of our head we tend to grow unconscious of our feet, and there enters thus an element of time-succession into our percep- tion of ourselves which transforms the latter from an act of intuition to one of construction. This element of con- structiveness is present in a still higher degree, and carries with it the same consequences, when we deal with objective spaces too great to be grasped by a single look. The rela- tive positions of the shops in a town, separated by many tortuous streets, have to be thus constructed from data ap- prehended in succession, and the result is a greater or less degree of vagueness. That a sensation be discriminated as a part from out of a larger enveloping space is then the conditio sine qud non of its being apprehended in a definite spatial order. The problem of ordering our feelings in space is then, in the first instance, a problem of discrimination, but not of discrimination pure and simple ; for then not only coexistent sights but coex- istent sounds would necessarily assume such order, which they notoriously do not. Whatever is discriminated will appear as a small space within a larger space, it is true, but this is but the very rudiment of order. For the location of it within that space to become precise, other conditions still must supervene ; and the best way to study what they are will be to pause for a little and analyze what the expression * spatial order ' means. Spatial order is an abstract term. The concrete percep- tions which it covers are figures, directions, positions, mag- nitudes, and distances. To single out any one of these things from a total vastness is partially to introduce order into the vastness. To subdivide the vastness into a multi- tude of these things is to apprehend it in a completely orderly way. Now what are these things severally ? To 148 P8TCH0L00T. begin with, no one can for an instant hesitate to saj that some of them are qualities of sensation, just as the total yastness is in which they lie. Take figure : a square, a circle, and a triangle appear in the first instance to the eye simply as three different kinds of impressions, each so pecul- iar that we should recognize it if it were to return. When Nunnely's patient had his cataracts removed, and a cube and a sphere were presented to his notice, he could at once perceive a difference in their shapes ; and though he could not say which was the cube and which the sphere, he saw they were not of the same figure. So of lines : if we can notice lines at all in our field of vision, it is inconceivable that a vertical one should not affect us differently from an horizontal oue, and should not be recognized as affecting us similarly when presented again, although we might not yet know the name * vertical,' or any of its connotations, beyond this peculiar affection of our sensibility. So of angles : an obtuse one affects our feeling immediately in a different way from an acute one. Distance-apart, too, is a simple sensa- tion — the sensation of a line joining the two distant points : lengthen the line, you alter the feeling and with it the distance felt. Space-rdations. But with distance and direction we pass to the category of space-reTo^iorw, and are immediately confronted by an opinion which makes of all relations something toto ccdo different from all facts of feeling or imagination whatsoever. A relation, for the Platonizing school in psychology, is an energy of pure thought, and, as such, is quite incommen- surable with the data of sensibility between which it may be perceived to obtain. We may consequently imagine a disciple of this school to say to us at this point : " Suppose you have made a sep- arate specific sensation of each line and each angle, what boots it ? You have still the order of directions and of distances to account for ; you have still the relative magni- tudes ot all these felt figures to state ; you have their re- spective positions to define before you can be said to have brought order into your space. And not one of these de- TEE PERCEPTION OF 8PA0E. 149 terminations can be effected except through an act of re* lating thought, so that your attempt to give an account of space in terms of pure sensibility breaks down almost at the very outsei Position, for example, can never be a sen- sation, for it has nothing intrinsic about it ; it can only obtain between a spot, line, or other figure and extraneous co-ordinateSy and can never be an element of the sensible datum, the line or the spot, in itsell Let us then confess that Thought alone can unlock the riddle of space, and that Thought is an adorable but unfathomable mystery." Such a method of dealing with the problem has the merit of shortness. Let us, however, be in no such hurry, but see whether we cannot get a little deeper by patiently considering what these space-relations are. 'Relation' is a very slippery word. It has so many different concrete meanings that the use of it as an abstract universal may easily introduce bewilderment into our thought We must therefore be careful to avoid ambiguity by making sure, wherever we have to employ it, what its precise meaning is in that particular sphere of application. At present we have to do with space-relations, and no others. Most ' relations ' are feelings of an entirely different order from the terms they relate. The relation of similarity, e.g., may equally obtain between jasmine and tuberose, or be- tween Mr. Browning's verses and Mr. Story's ; it is itself neither odorous nor poetical, and those may well be pardoned who have denied to it all sensational content whatever. But just as, in the field of quantity, the relation between two numbers is another number, so in the field of space the relations are facts of the same order with the facts they relate. If these latter be patches in the circle of vision, the former are certain other patches betioeen them. When we speak of the relation of direction of two points toward each other, we mean simply the sensation of the line that joins the two points together. The line is the rdaiion; feel it and you feel the relation, see it and you see the relation ; nor can you in any conceivable way think the latter except by im- agining the former (however vaguely), or describe or indi- cate the one except by pointing to the other. And the moment you have imagined the line, the relation stands 160 PaTOHOLOQT. before you in all its completeness, with nothing farther tc be done. Just so the relation of direction between two lines is identical with the peculiar sensation of shape of the space enclosed between them. This is commonly called an angular relation. If these relations are sensations, no less so are the rela- tions of position. The relation of position between the top and bottom points of a vertical line is that line^ and nothing else. The relations of position between a point and a horizontal line below it are potentially numerous. There is one more important than the rest, called its distance. This is the sensation, ideal or actual, of a perpendicular drawn from the point to the line.* Two lines, one from each extremity of the horizontal to the point, give us a peculiar sensation of triangularity. This feeling may be said to constitute the locus of all the relations of position of the elements in ques- tion. Bightness and Irftness, upness and dotvnness, are again pure sensations diflfering specifically from each other, and generically from everything else. Like all sensations, they can only be indicated, not described. If we take a cube and label one side top, another bottoniy a third /ron^, and a fourth back, there remains no form of words by which we can de- scribe to another person which of the remaining sides is right and which left. AVe can only point and say here is right and there is left, just as we should say this is red and thaJt blue. Of two points seen beside each other at all, one is always afiected by one of these feelings, and the other by the opposite; the same is true of the extremities of any line.t * The whole science of geometry may be said to owe Its being to the exorbitant interest which the human mind takes in lines. We cut space up in every direction in order to manufacture them. f Kant was, I believe, the first to call attention to this last order of facts. After pointing out that two opposite spherical triangles, two gloves of a pair, two spirals wound in contrary directions, have identical inward de- terminations, that is, have their parts defined with relation to each other by the sam'j law, and so must be conceived as identical, he showed that the im- possibility of their mutual superposition obliges us to assign to each figure of a symmetrical pair a peculiar difference of its own which can only con- sist in an outward determination or relation of its parts, no longer to c»ach other, but to the whole of an objectively outlying space with its points of the iy in a blank way that when il is excited alone, it is an • ultimate fact '(1) that a positionless spot will appear; that when it is excited together with other similar processes, but inthout the process of discriminative attention, it is another ' ultimate fact ' (2) that a unitary line will come; and that the final * ultimate fact ' (8) is that, when the nerve- process is excited in combination with that other process which subserves the feeling of attention, what results will be the line with the local sign inside of it determined to a particular place. Thus we should escape the responsibility of explaining, by falling back on the everlasting inscruta- bility of the psycho-neural nexus. The moment we call the ground of lo- calization physiological, we need only point out how, in those cases in which localization occurs, the physiological process differs from those in which it does not, to have done all we can possibly do in the matter. This would be unexceptionable logic, and with it we might let the matter drop, satisfied that there was no self-contradiction in it, but only the universal psychological puzzle of how a new mode of consciousness emerges when- ever a fundamentally new mode of nervous action occurs. But, blameless as such tactics would logically be on our part, let us see whether we cannot push our theoretic insight a little farther. It seems to me we can. We cannot, it is true, give a reason why the line we feel when process (2) awakens should have its own peculiar shape; nor can we explain the essence of the process of discriminative attention. But we can see why, if the brute facts be admitted that a line may have one of its parts singled out by attention at all, and that that part may appear in relation to THE PERCEPTION OF SPACE. 165 every sense, experience takes a5 initio the spatial form. We have also shown that in the cases of the retina and skin other parts at all, the relation must be in the line iUe^,^~toT the line and the parts are the only things supposed to be in consciousness. And we can furthermore suggest a reason why parts appearing thus in relation to each other in a line should fall into an immutable order, and each within that order keep its characteristic place. If a lot of such local signs all have any quality which evenly augments as we paf« from one to the other, we can arrange them in an ideal serial order, in which any one local sign must lie below those with more, above those with less, of the quality in question. It must divide the series into two parts, — unless indeed it have a maximum or minimum of the quality, when it either begins or ends it. Such an ideal series of local signs in the mind is, however, not yet iden- tical with the feeling of a line in space. Touch a dozen points on the skin eueeeseively, and there seems no necessary reason why the notion of a defi- nite line should emerge, even though we be strongly aware of a gradation of quality among the touches. We may of course symbolically arrange them in a line in our thought, but we can always distinguish between a line symbolically thought and a line directly felt. But note now the peculiarity of the nerve-processes of all these local signs: though they may give no line when excited successively, when ex- cited together tbey do give the actual sensation of a line in space. The sum of them is the neural process of that line; the sum of their feelings is the feeling of that line: and if we begin to single out particular points from the line, and notice them by their rank, it is impossible to see how this rank can appear except as an actual fixed space-position sensibly felt as a bit of the total line. The scale itself appeariug as a line, rank in it must appear as a definite part of the line. If the seven notes of an octave, when heard together, appeared to the sense of hearing as an outspread line of sound— which it is needless to say they do not— why then no one note could be discriminated without being localized, according to its pitch, in the line, either as one of its extremities or as some part between. But not alone the gradation of their quality arranges the local-sign feelings in a scale. Our movements arrange them also iu a fme-scale. Whenever a stimulus passes from point a of the skin or retina to point/, it awakens the local-sign feelings in the perfectly definite time-order abcdef. It cannot excite/ until cde have been successively aroused. The feeling e sometimes is preceded by ab. sometimes followed by ba, according to the movement's direction: the result of it all being that we never feel either a, c, or/, without there clinging to it faint reverberations of the various time- orders of transition in which, throughout past experience, it has been aroused. To the local sign a there clings the tinge or tone, the penumbra orfringe. of the transition bed. To/ to c, there cling quite different tones. Once admit the principle that a feeling may be tinged by the reproductive consciousness of an habitual transition, even when the transition is not made, and it seems entirely natural to admit that, if the transition be habit- ually in the order abcdef ^ and if a, c, and/ be felt separately at all, a will be felt with an essential earliness, f with an essential lateness, and that c wiU 166 PUTOHOLOQY, every sensible total may be subdivided by disoiinmiative attention into sensible parts, which are also spaces, and into relations between the parts, these being sensible spaces too. Furthermore, we have seen (in a foot-note) that differ- ent parts, once discriminated, necessarily fall into a deter- minate order, both by reason of definite gradations in their quality, and by reason of the fixed order of time-succes- sion in which movements arouse them. But in all thii^ nothing has been said of the comparative measurement of one sensible space-total against another, or of the way in which, by summing our divers simple sensible space- experiences together, we end by ronstructing what we re- gard as the unitary, continuous, and infinite objective Space of the real world. To this more difficult inquiry we next pass. THE CONSTBUOnON OF 'BEAIi' 8PAOB. The problem breaks into two subordinate problems . (1) How is the subdivision and measurement of the several sensorial spaces completely effected? and (2) Hoiv do their mutual addition and fusion and reduction to the same scale, in a ivord, hoiv does their synthesis, occur ? I think that, as in the investigation just finished, we found ourselves able to get along without invoking any data but those that pure sensibility on the one hand, and the ordinary intellectual powers of discrimination and recollec- fall between. Thus those psycliologists who set little store by local signs and great store by movements in explaining space-perception, would have a perfectly definite time-order, due to motion, by which to account for the definite order of positions thai appears when sensitive spots are excited all at once. Without, however, the preliminary admission of the * ulti- mate fact' that this collective excitement shall feel like a U/i€ and nothing- else, it can never be explained why the new order should needs be an order of positions, and not of merely ideal serial rank. We shall hereafter have any amount of opportunity to observe how thoroughgoing is the par- ticipation of motion in all our spatial measurements. Whether the local signs have their respective qualities evenly graduated or not. the feelings of transition must be set down as among the Ter(P causa> in localization. But the gradation of the local signs is hardly to be doubted: so we may be- lieve ourselves really to possess two sets of reasons for localizing any point we may happen to distinguish from out the midst of any line or any larger •pace. THS PBRCBPTION OF SPACE. 1(57 idon on the other, were able to yield; so here we shall emerge from our more complicated quest with the convic- tion that all the facts can be accounted for on the supposi- tion that no other mental forces have been at work save those we find everywhere else in psychology : sensibility, namely, for the data ; and discrimination, association, memory, and choice for the rearrangements and combina- tions which they undergo. 1. The Svbdiviaion of the Original Sense-spaces. How are spatial subdivisions brought to consciousness ? in other words, How does spatial discrimination occur? The general subject of discrimination has been treated in a previous chapter. Here we need only inquire what are the conditions that make spatial discrimination so much finer in sight than in touch, and in touch than in hearing, smell, or taste. The first great condition is^ that different points of the surface shall differ in the qvality of their immanent sensibility ^ that is, that each shall carry its special local-sign. If the skin felt everywhere exactly alike, a foot-bath could be dis- tinguished from a total immersion, as being smaller, but never distinguished from a wet face. The local-signs are indispensable ; two points which have the same local-sign will always be felt as the same point We do not judge them two unless we have discerned their sensations to be different.* Granted none but homogeneous irritants, that organ would then distinguish the greatest multiplicity of irritants — would count most stars or compass-points, or best compare the size of two wet surfaces — whose local sensibility was the least even. A skin whose sensibility shaded rapidly off from a focus, like the apex of a boil, would be better than a homogeneous integument for spatial perception. The retina, with its exquisitely sensitive fovea, has this peculiarity, and undoubtedly owes to it a great part ♦M. Binet (Revue Philosophique, Sept. 1880, page 291) says we judge them locally different as soon as their sensations differ enough for us to distinguish them as qqalitatively different when successively excited. This is not strictly true. Skin-sensations, different enough to be discriminated when succesnne, may still fuse locally if excited both at once. 168 PaTCHOLOQT. of the minuteness with which we are able to subdivide the total bigness of the sensation it yields. On its periphery the local differences do not shade off very rapidly, and we can count there fewer subdivisions. But these local differefruxa of feeling ^ so long as the aurfaoe is unexcited from without^ are almost nvU, I canot feel them by a pure mental act of attention unless they belong to quite distinct parts of the body, as the nose and the lip, the finger- tip and the ear ; their contrast needs the reinforcement of outward excitement to be felt In the spatial muchness of a colic — or, to call it by the more spacious-sounding verna- cular, of a * bellyache '—one can with difficulty distinguish the north-east from the south-west comer, but can do so much more easily if, by pressing one's finger against the former region, one is able to make the pain there more in- tense. The local differefrvces require then an adventitious sensa^ tion, superinduced upon them, to atvaken the attention. After the attention has once been awakened in this way, it may continue to be conscious of the unaided difference ; just as a sail on the horizon may be too faint for us to notice until someone's finger, placed against the spot, has pointed it out to us, but may then remain visible after the finger has been withdrawn. But all this is true only on condition that separate points of the surface may be exdvsivdy stimulated. If the whole surface at once be excited from without, and homogeneously, as, for example, by immersing the body in salt water, local discrimination is not furthered. The local- signs, it is true, all awaken at once ; but in such multitude that no one of them, with its specific quality, stands out in contrast with the rest If, however, a single extremity be immersed, the contrast between the wet and dry parts is strong, and, at the surface of the water especially, the local- signs attract the attention, giving the feeling of a ring sur- rounding the member. Similarly, two or three wet spots separated by dry spots, or two or three hard points against the skin, will help to break up our consciousness of the latter's bigness. In cases of this sort, where points re- ceiving an identical kind of excitement are, nevertheless, felt to be locally distinct, and the objective irritants are also THE PERCEPTION OF SPACE. 169 judged multiple, — e.g., compass-points on skin or stars on retina, — the ordinary explanation is no doubt just, and we judge the outward causes to be multiple because we have discerned the local feelings of their sensations to be dif- ferent. Capacity for ^partial stimtikUion is thus the second condi" tion/avoring discrimination. A sensitive surface which has to be excited in all its parts at once can yield nothing but a sense of undivided largeness. This appears to be the case with the olfactory, and to all intents and purposes with the gustatory, surfaces. Of many tastes and flavors, even sim- idtaneously presented, each affects the totality of its re- spective organ, each appears with the whole vastness given by that organ, and appears interpenetrated by the rest* * It may. however, be said that even in the tongue there is a determina- tion of bitter tiavors to the buck and of acids to the front edge of the organ. Spices likewise affect its sides and front, and a taste like that of alum localizes itself, by its styptic effect on the portion of mucous membrane, which it immediately touches, more sharply than roast pork, for example, which stimulates all parts alike. The pork, therefore, tastes more spacious than the alum or the pepper. In the nose, too, certain smells, of which vinegar may be taken as the type, seem less spatially extended than heavy, suffocating odors, like musk. The reason of this appears to be that the former inhibit inspiration by their sharpness, whilst the latter are drawn into the lungs, and thus excite an objectively larger surface. The ascr p- lion of height and depth to certain notes seems due, not to any localization of the sounds, but to the fact that a feeling of vibration in the chest and tension in the gullet accompanies the singing of a bass note, whilst, when we sing high, the palatine mucous membrane is drawn upon by the muscles which move the larynx, and awakens a feeling in the roof of the mouth. The only real objection to the law of partial stimulation laid down in the text is one that might be drawn from the organ of hearing; for, ac- cording to modem theories, the cochlea may have Its separate nerve-termini exclusively excited by sounds of differing pitch, and yet the sounds seem all to fill a common space, and not necessarily to be arranged alongside of each other At most the high note is felt as a thinner, brighter streak against a darker ))ackground. In an article on Space, published in the Journal of Speculative Philosophy for January, 1879, 1 ventured to suggest that possibly the auditory nerve termini might be "excited all at once by sounds of any pitch, as the whole retina would be by every luminous point if there were no dioptric apparatus, affixed.*' And I added : " Notwith- standing the brilliant conjectures of the last few years which assign differ- ent acoustic end-organs to different rates of air- wave, we are still greatly in the dark about the subject : and. I, for ihy part, would much more con- fidently reject a theory of hearing which violated the principles advanced in 170 PSYCHOLOGY. I should have been willing some years ago to name with* out hesitation a third condition of discrimination — saying it would be most developed in that organ which is susceptible of the moat variom qttalities of feeling. The retina is un- questionably such an organ. The colors and shades it perceives are infinitely more numerous than the diversities of skin -sensation. And it can feel at once white and black, whilst the ear can in nowise so feel sound and silence. But the late researches of Donaldson, Blix, and Qt)ldscheider, * on specific points for heat, cold, pressure, and pain in the skin ; the older ones of Czermak (repeated later by £lug in Ludwig's laboratory), showing that a hot and a cold compass-point are no more easily discriminated as two than two of equal temperature ; and some unpublished experi- ments of my own — all disincline me to make much of this condition now.t There is, however, one quality of sensa- tbis article than give up those principles for the sake of any hypothesis hitherto published about either organs of Corti or basilar membrane." Professor Rutherford's theory of hearing, advanced at the meeting of the British Association for 1886, already furnishes an%lternative view which would make heariug present no exception to the space-theory I defend and which, whether destined to be proved true or false, ought, at any rate to make us feel that the Helmholtzian theory is probably not the last wora in the physiology of heariug. Stepano. S. (Hermann und Schwalbe's Jahres- bericht, xv. 404. Literature 1886) reports a case in which more than the upper half of one cochlea was lost without any such deafness to deep notes on that side as Helmholtz's theory would require. * ♦ Donaldson, in Miud, x. 399, 577; Goldscheider, in Archiv f . (Anat u.) Physiologic; Blix, in Zeitsclirift fUr Biologic. A good resume may be found in Ladd's Physiol. Psychology, part ii. chap. rv. §§ 21-28. f I tried on nine or ten people, making numerous observations on each, what difference it made in the discrimination of two points to have them alike or unlike. The points chosen were (1) two large needle-heads, (2) two screw-heads, and (3) a needle-head and a screw-head. The distance of the screw-heads was measured from their centres. I found that when the points gave diverse qualities of feeling (as in 8), this facilitated the discrimination, but much less strongly than I expected The difference, in fact, would often not be perceptible twenty times running When, however, one of the points was endowed with a rotary movement, the other remaining still, the doubleness of the points became much more evi- dent than before. To observe this I took an ordinary pair of compasses with one point blunt, and the movable leg replaced by a metallic rod which couhi. at any moment, be made to rotate in situ by a dentist's drilling-machine, to which it was attached. The compass had then its points applied to the skin at such a distance apart as to be felt as one impression. Suddenly rotating the drill-apparatus then almost always made them seem as two. THB PERCEPTION OF 8PACK 171 tion which is particularly exciting, and that is the feding of motion over any of our surfaces. The erection of this into a separate elementary quality of sensibility is one of the most recent of psychological achievements, and is worthy of detaining us a while at this point The Sensation of Motion over Surfaces. The feding of motion has generally been assumed by physiologists to be impossible until the positions of terminus a quo and terminus ad quern are severally cognized, and the successive occupancies of these positions by the moving body are perceived to be separated by a distinct interval of time.* As a matter of fact, however, we cognize only the very slowest motions in this way. Seeing the hand of a clock at XII and afterwards at YI, we judge that it has moved through the interval Seeing the sun now in the east and again in the west, I infer it to have passed over my head. But we can only infer that which we already generically know in some more direct fashion, and it is ex- perimentally certain that we have the feeling of motion given us as a direct and simple sensation. Czermak long ago pointed out the difference between seeing the motion of the second-hand of a watch, when we look directly at it, and noticing the fact of its having altered its position when we fix our gaze upon some other point of the dial-plate. In the first case we have a specific quality of sensation which is absent in the second. If the reader will find a portion of his skin — the arm, for example — where a pair of com- pass-points an inch apart are felt as one impression, and if be will then trace lines a tenth of an inch long on that spot with a pencil-point, he will be distinctly aware of the point's motion and vaguely aware of the direction of the motion. The perception of the motion here is certainly not derived from a pre-existing knowledge that its starting and ending points are separate positions in space, because positions in space ten times wider apart fail to be discriminated as such • This is only another example of what I call ' the psychologist's fal- lacy '—thinking that the mind he is studying must necessarily be conscious «f the object after the fashion in which the psychologist himself is con- scious of it. 172 PSYCHOLOGY. when excited by the dividers. It is the same with the retina. One's fingers when cast upon its peripheral portions cannot be counted — that is to say, the five retinal tracts which they occupy are not distinctly apprehended by the mind as five separate positions in space — and yet the slight- est movement of the fingers is most vividly perceived as movement and nothing else. It is thus certain that our sense of movement, being so much more delicate than our sense of position, cannot possibly be derived from it. A curiovs observation by Exner * completes the proof that move- ment is a primitive form of sensibility, by showing it to be much more delicate than our sense of succession in time. This very able physiologist caused two electric sparks to appear in rapid succession, one beside the other. The observer had to state whether the right-hand one or the left-hand one appeared first When the interval was re- duced to as short a time as 0.044^^ the discrimination of temporal order in the sparks became impossible. But Exner found that if the sparks were brought so close to- gether in space that their irradiation-circles overlapped, the eye then felt their flashing as if it were the motion of a single spark from the point occupied by the first to the point occupied by the second, and the time-interval might then be made as small as 0.015" before the mind began to be in doubt as to whether the apparent motion started from the right or from the left. On the skin similar ex- periments gave similar results. Vierordt, at almost the same time;\ called atttention to cer- tain persistent illusions, amongst ivhich are these : If another person gently trace a line across our wrist or finger, the latter being stationary, it will feel to us as if the mem- ber were moving in the opposite direction to the tracing point. If, on the contrary, we move our limb across a fixed point, it will be seen as if the point were moving as well. If the reader will touch his forehead with his forefinger kept motionless, and then rotate the head so that the skin of the forehead passes beneath the finger's tip, he will have — •Sitzb. der. k. Akad. Wien, Bd. lxxii.. Abth. 8 (1875). t Zeilschrift fOr Biologic, xii. 2'26 (1876). THE PERCEPTION OF SPACE. 173 an irresistible sensation of the latter being itself in motion in the opposite direction to the head. So in abducting the fingers from each other ; some may move and the rest be still still, but the still ones will feel as if thej were actively sep- arating from the rest These illusions, according to Vierordt, are survivals of a primitive form of perception, when motion was felt as such, but ascribed to the whole content of consciousness, and not yet distinguished as belonging ex- clusively to one of its parts. When our perception is fully developed we go beyond the mere relative motion of thing and ground, and can ascribe absolute motion to one of these components of our total object, and absolute rest to another. When, in vision for example, the whole background moves together, we think that it is ourselves or our eyes which are moving ; and any object in the foreground which may move relatively to the background is judged by us to be still. But primitively this discrimination cannot be per- fectly made. The sensation of the 'motion spreads over all that we see and infects it. Any relative motion of object and retina both makes the object seem to move, and makes us feel ourselves in motion. Even now when our whole ob- ject moves we still get giddy ; and we still see an apparent motion of the entire field of view, whenever we suddenly jerk our head and eyes or shake them quickly to and fro. Pushing our eyeballs gives the same illusion. We knoiv in all these cases what really happens, but the conditions are unusual, so our primitive sensation persists unchecked. So it does when clouds float by the moon. We know the moon is still ; but we see it move even faster than the clouds. Even when we slowly move our eyes the primitive sensation persists under the victorious conception. If we notice closely the experience, we find that any object towards which we look appears moving to meet our eye. But the most valuable contribution to the subject is the paper of G. H. Schneider,* who takes up the matter zoologically, and shows by examples from every branch of the animal kingdom that movement is the quality by which animals most easily attract each other's attention. The in- * Vierteljahrsch. fttr wiss. Philos., n. 877. 174 PSYCHOLOGY, stmct of ' shamming death ' is no shamming of death at all, but rather a paralysis through fear, which saves the insect, crustacean, or other creature from being noticed at aRhj\ns enemy. It is parallelled in the human race by the breath- holding stillness of the boy playing * I spy,' to whom the seeker is near ; and its obverse side is shown in our invol- untary waving of arms, jumping up and down, and so forth, when we wish to attract someone's attention at a distance. Creatures ' stalking * their prey and creatures hiding from their pursuers alike show how immobility diminishes con- spicuity. In the woods, if we are quiet, the squirrels and birds will actually touch us. Flies will light on stuffed birds and stationary frogs.* On the other hand, the tre- mendous shock of feeling the thing we are sitting on begin to move, the exaggerated start it gives us to have an insect unexpectedly pass over our skin, or a cat noiselessly come and snuffle about our hand, the excessive reflex effects of tickling, etc., show how exciting the sensation of motion is per 86, A kitten cannot help pursuing a moving ball. Im- pressions too faint to be cognized at all are immediately felt if they move. A fly sitting is unnoticed, — we feel it the moment it crawls. A shadow may be too faint to be per- ceived. As soon as it moves, however, we see it. Schneider found that a shadow, with distinct outline, and directly fix- ated, could still be perceived when moving, although its objective strength might be but half as great as that of a stationary shadow so faint as just to disappear. With a blurred shadow in indirect vision the difterence in favor of motion was much greater — namely, 13.3 : 40.7. If we hold a finger between our closed eyelid and the sunshine we shall not notice its presence. The moment we move it to and fro, however, we discern it. Such visual perception as this reproduces the conditions of sight among the radiates, t * Exner tries to show that the structure of the faceted eye of articulates adapts it for perceiving motions almost exohisively. t Schneider tries to explain why a sensory surface is so much more ex- cited when its impression moves. It lias long since been noticed how much more acute is discrimination of successive than of simultaneous differences. But in the case of a moving impression, say on the retina, we have a sum- THE PERCEPTION OF SPACE, 175 Enough has now been said to show that in the education of spatial discrimination the motions of impressions across sen- sory surfaces mvst have been the principal argent in breaking up our consciousness of the surfaces into a consciousness of their parts. Even to-day the main function of the pe- ripheral regions of our retina is that of sentinels, which, when beams of light move over them, cry * Who goes there ? * and call the fovea to the spot Most parts of the skin do but perform the same office for the finger-tips. Of course finger-tips and fovea leave some power of direct perception to marginal retina and skin respectively. But it is worthy of note that such perception is best developed on the skin of the most movable parts (the labors of Vierordt and his pupils have well shown this) ; and that in the blind, whose skin is exceptionally discriminative, it seems to have become BO through the inveterate habit which most of them possess of twitching and moving it under whatever object may touch them, so as to become better acquainted with the con- formation of the same. Czermak was the first to notice this. It may be easily verified. Of course movement of sttr/ace under object is {/or purposes of stimulation) equivalent to move- ment of object over surface. In exploring the shapes and matioD of both sorts of differeDce ; whereof the natural effect must be to produce the most perfect discrimination of all. A B JL B Fio. 68. In the left-hand figure let the dark spot B move, for example, from right to left. At the outset there is the simultaneous contrast of black and white in Band A. When the motion has occurred so that the right-hand figure is produced, the same contrast remains, the black and the white having changed places. But in addition to it there is a double suc- cessive contrast, first in A, which, a moment ago white, has now become black : and second in B, which, a moment ago black, has now become white. If we make each single feeling of contrast = 1 (a supposition lar too favorable to the state of rest), the sum of contrasts in the case of motion will be 8, as against 1 in the state of rest. That is, our attention will be called by a treble force to the dilTerence of color, provided the color be gin to move. — (Cf. also Fleischl. Fhysiologische Optische T^otizen, 2te Mitiheilung, Wiener Sitzungsberichte, 1882.) 176 PSYCHOLOGY, sizes of things by either eye or skin the movements of these organs are incessant and unrestrainable. Every such move- ment draws the points and lines of the object across the surface, imprints them a hundred times more sharply, and drives them home to the attention. The immense part thus played by movements in our perceptive acti>dty is held by many psychologists* to prove that the muscles are them- selves the space-perceiving organ. Not surface-sensibility, but ^ the muscular sense/ is for these writers the original and only revealer of objective extension. But they have all failed to notice with what peculiar intensity muscular contractions call surface-sensibilities into play, and that the mere discrimination of impressions (quite apart from any question of measuring the space between them) largely depends on the mobility of the surface upon which they fall, t * Brown, Bain. J. 8. Mill, and in a modified manner Wundt, Helmhollz. Sully, etc. fW. Oil. Dunan, in his forcibly written essay MEspace Visuel et I'Espace Tactile* in the Heviie Philosophique for 1888, endeavors to prove that surfaces alone give no perception of extent, by citiug the way in which the blind go to work to gain an idea of an object's shape. I f surfaces were the percipient organ, he says. " both the seeing and the blind ought to gain an exact idea of the size (and shape) of an object by merely laying their hand flat upon it (provided of course that it were smaller than the hand), and this because of their direct appreciation of the amount of tactile surface affected, and with no recourse to the muscular sense. . . . But the fact is that a person born blind never proceeds in this way to measure ob- jective surfaces. The only means which he has of getting at the size of a body is that of running his finger along the lines by which it is bounde