G. Rhymes imperfectly. Ta ta ta ta ta ta ta dò) gò) dó dò Hu. Rhymes well. Mc. Rhymes well. G. Rhymes well. Ta ta ta ta ta ta ta dò gò) dó) dò) Hu. Cannot get rhyme. Hy. Cannot get rhyme. 'Accent spoils it.' G. Cannot get rhyme. 'Accent breaks it all up.' Mc. Rhymes imperfectly. The table shows that rhymes of syllables which have accents of strikingly different degrees are difficult to feel. In the last case, of the rhyming verses separated by a verse having a heavy end accent, it was practically impossible to hear the rhyme across the break made by the heavy accent. Somehow the particular condition of the organism which constitutes the expectation of a rhyme is broken up by a heavy accent. The material for the records of Table V. was read to the subjects, the tones were in every case those of the speaking voice, and intervals having a definite speech character were chosen. The fifth is the interval of the rising inflection of the question, the fourth is the interval of the rising inflection of indifference or negation, and the single falling slide used is a descending interval of a third or fourth at the close of the sentence. The fifth appears in the table as 5/, the fourth as 4/, and the single descending interval of finality as the period (.). Each verse was read on approximately the first tone of the interval, the rhyming syllable only had the second tone of the interval. TABLE V. RHYMES UNDER GIVEN PITCH CONDITIONS. Iambic tetrameters: two-verse stanzas. The body of the verse is omitted; the closing intervals alone are indicated. '1' is read 'good rhyme;' '2' is 'poor rhyme'; and '0' is 'no rhyme.' Couplets: --do 5/} 5/} .} .} 5/} --go .} 4/} 5/} .} 5/} G. 2 2 0 S. 0 0 2 1 R. 2 2 1 2 2 Mc. 0 0 0 1 1 Hu. 0 0 ? 1 Ha. 1 2 1 2 Iambic tetrameters; four-verse stanzas. Rhymes are indicated by 'a' and 'a,' 'b' and 'b.' Capital* letters are read 'poor rhyme;' 'o' is read 'no rhyme.' I. II. III. IV. I. II. III. IV. I. II. III. IV. I. II. III. IV. do, no, go, so. do, no, go, so. do, no, go, so. do, no, go, so. 5/ . 5/ . . 5/ . 5/ 5/ 5/ . . 5/ 5/ . 5/ G. a b a b a b a b a a b b a a a o R. a b a b a a b b Mc. a b a b a o a o Hu. a b a b a b a b a a b b a a o a Ha. a b a b o o o o a a B B a a o a 5/ 5/ 5/ . . . . 5/ . . . . . 5/ . . G. a a a a a a a o a a a a o o a a Hu. a a a o a a a o a a a a a o a a Ha. a a a o a a A o a a a a a o a a Mc. a a a o a a a o A A A A A o A A R. a a a o a a a o a a a a A o A A 5/ 5/ 4/ 5/ . . 5/ 5/ 5/ . 4/ . 5/ . . 5/ G. a a o o /a a b b /o a o a o o o o \a b a b \A A B B R. A A A A /o o a a\ a a b b \a a o o/ Hu. a a o a Mc. a a o a A A B B Ha. A A B B a a b b o a o a 4/ 4/ 4/ . 5/ 5/ 5/ 5/ 5/ 4/ 5/ 4/ G. a a a a o a o a Mc. a a a o R. a a a o a a b b Ha. A A A A *Transcriber's Note: Original used italic lower case letters. The table shows that there is a decided tendency to prefer rhymes in which the members of the rhyme have the same interval. The only exception is in the case of couplets, where two contrasting slides 5/ and . rhyme, whenever the finality interval occurs last. Perhaps the similarity of pitch of the rhyming syllables is a part of the 'Gestaltqualität' whose recognition brings about the release and satisfaction of the state which we know as the 'feeling of expecting a rhyme.' Definite pitch relations in music seem to make rhyme of little significance. We seldom notice the rhymes in a hymn or in a song of any musical worth. In comic operas and popular ditties rhyme does now and then figure. In such cases the pitch of the two or more rhyming syllables is identical; often the whole phrase is repeated for each rhyming verse. A few experiments in singing a rhyme to simple intervals show that when the identical interval is used the two syllables rhyme well, but if the interval be in the opposite direction, or in another chord, the rhyme is very uncertain. It seems that in music we usually have 'feelings of expectation' (_i.e._, tensions of some sort, central or peripheral), which are adequate to unite the phrases into larger unities. These tensions are so definite and vivid that they quite obscure and swallow up the related condition of rhyme expectation. These experiments on the modification of the rhyme by the various pitch and accent factors are not at all exhaustive or conclusive. An extended series of experiments is needed. The study of sound records for pitch is peculiarly tedious, but it should reveal some interesting relations between rhyme and speech melody. III. THE SPEAKING OF A RHYTHMIC SERIES. I. _Methods of Making Speech Records._ The study of spoken rhythm is of primary importance. Observations on what the subject really does are always open to the objections that subjective factors play a large part, and that the observer's perception of a rhythm is after all _his_ perception of the rhythm, not the subject's. The voice is an important indicator of the activities which generate the rhythms of verse and music, and some objective method of measuring the sounds made is essential to a study of the rhythm production. Methods of recording and studying the tones of the voice are as numerous as they are unsatisfactory. In the main the work has been done for purposes of phonetics, and but few of the methods are applied in the psychological laboratory. Marage[13] has an excellent summary of the methods with practical comments on their applicability. Rousselot[14] (Histoire des applications de phonétique expérimentale, 401-417: objets et appareils, 1-10 et 669-700) gives a careful history of the methods from the phonetic point of view. Scripture[15] gives a convenient English summary of the processes. [13] Marage: _l'Année psychologique_, 1898, V., p. 226. [14] Rousselot: La Parole, 1899. [15] Scripture, E.W.: _Studies from the Yale Psych. Lab._, 1899, VII., p. I. A few methods have been devised which avoid the difficulties incident to the use of a diaphragm, but they are not applicable to the measurement of rhythm material. The instruments which might be used for recording spoken rhythms are all modifications of two well-known forms of apparatus, the phonautograph and the phonograph. The phonograph record is incised in wax, and presents special difficulties for study. Boeke, however, has studied the wax record under a microscope, with special arrangements for illumination. The work is quite too tedious to permit of its use for material of any length, though it is fairly satisfactory when applied to single vowels. In order to enlarge the record, and at the same time to obtain the curves in the plane of the record surface, Hermann devised an attachment to the phonograph (cf. Marage, loc. citat.) by which the movements of the stylus of the phonograph are magnified by a beam of light and recorded on photographic paper. The measurements of entire words by this method would be as tedious as by Boeke's. E.W. Scripture has chosen another type of talking machine from which to obtain transcribed records. The permanent record of the gramophone (which makes a record in the plane of the surface, like the phonautograph) is carefully centered, and a lever attached to a stylus which follows the furrow of the record transcribes the curve on the kymographic drum as the plate is slowly revolved. The method has the advantage of using a record which may be reproduced (_i.e._ the original gramophone record may be reproduced), and of giving fairly large and well defined curves for study. It is too laborious to be applied to extended research on speech rhythms, and has besides several objections. The investigator is dependent on the manufacturer for his material, which is necessarily limited, and cannot meet the needs of various stages of an investigation. He knows nothing of the conditions under which the record was produced, as to rate, on which time relations depend, as to tone of voice, or as to muscular accompaniments. There are also opportunities for error in the long lever used in the transcription; small errors are necessarily magnified in the final curve, and the reading for intensity (amplitude of the curve) is especially open to such error. The stylus of such a recording apparatus as is used by the gramophone manufacturers, is subject to certain variations, which may modify the linear measurements (which determine time relations). The recording point is necessarily flexible; when such a flexible point is pressed against the recording surface it is dragged back slightly from its original position by friction with this surface. When the point is writing a curve the conditions are changed, and it sways forward to nearly its original position. This elongates the initial part of the sound curve. This fact is of little importance in the study of a single vowel, for the earlier part of the curve may be disregarded, but if the entire record is to be measured it is a source of error. Hensen[16] first turned the phonautograph to account for the study of speech. He used a diaphragm of goldbeater's skin, of conical shape, with a stylus acting over a fulcrum and writing on a thinly smoked glass plate. The apparatus was later improved by Pipping, who used a diamond in place of the steel point. The diamond scratched the record directly on the glass. The Hensen-Pipping apparatus has the advantage of taking records directly in the plane of the surface, but it does not make a record which can be reproduced; in case of doubt as to the exact thing represented by the curve, there is no means of referring to the original sounds; and it involves working with a microscope. [16] Hensen: Hermann's Handbuch d. Physiol., 1879, Bd. I., Th. II., S. 187. [Illustration: FIG. 3. Diagrammatic section of recording apparatus. _a_, diaphragm; _s_, stylus; _g_, guide; _p_, section of plate.] The apparatus which was used in the following experiments consisted essentially of two recording devices--an ordinary phonograph, and a recorder of the Hensen type writing on a rotary glass disc (see Fig. 5, Plate X.). Of the phonograph nothing need be said. The Hensen recorder, seen in cross section in Fig. 3, was of the simplest type. A diaphragm box of the sort formerly used in the phonograph was modified for the purpose. The diaphragm was of glass, thin rubber, or goldbeater's skin. The stylus was attached perpendicularly to the surface of the diaphragm at its center. The stylus consisted of a piece of light brass wire bent into a right angle; the longer arm was perpendicular to the diaphragm; the shorter arm was tipped with a very fine steel point, which pointed downward and wrote on the disc; the point was inclined a trifle to the disc, in order that it might 'trail,' and write smoothly on the moving disc. The stylus had no fulcrum or joint, but recorded directly the vibrations of the diaphragm. In early experiments, the diaphragm and stylus were used without any other attachment. But a flexible point writing on smoked glass is a source of error. When the disc revolves under the stylus, the flexibility of the diaphragm and of the stylus permit it to be dragged forward slightly by the friction of the moving surface. When the diaphragm is set vibrating the conditions are altered, and the stylus springs back to nearly its original position. The apparent effect is an elongation of the earlier part of the curve written, and a corresponding compression of the last verse written. This error is easily tested by starting the disc, and without vibrating the diaphragm stopping the disc; the stylus is now in its forward position; speak into the apparatus and vibrate the diaphragm, and the stylus will run backward to its original position, giving an effect in the line like _a_ (Fig. 4). If the error is eliminated, the stylus will remain in position throughout, and the trial record will give a sharp line across the track of the stylus as in _b_. [Illustration: FIG. 4.] This source of error was avoided by fixing a polished steel rod or 'guide' at right angles to the vertical part of the stylus, just in front of the stylus; the stylus trailed against this rod, and could not spring out of position. The friction of the rod did not modify the record, and the rod gave much greater certainty to the details of the sound curve, by fixing the position of the vibrating point. This rod or guide is shown in Fig. 3 (_g_). The disc was driven directly from the phonograph by a very simple method. A fine chain was fixed to the shaft carrying the disc, and wrapped around a pulley on the shaft. The chain was unwound by the forward movement of the recording apparatus of the phonograph against the constant tension of a spring. When the phonograph apparatus was brought back to the beginning of a record which had been made, the spring wound up the chain, and the disc revolved back to its original position. A T from the speaking-tube near the diaphragm box was connected by a rubber tube with the phonograph recorder, so that the voice of the speaker was recorded both on the smoked glass plate and on the phonograph cylinder. The advantages of such a double record are that the possible error of a transcription process is eliminated, and yet there is an original record to which it is possible to refer, and by which the record measured may be checked. An important feature in the method was the rate at which the disc revolved. The disc turned so slowly that the vibrations, instead of being spread out as a harmonic curve, were closely crowded together. This had two great advantages; the measurements were not so laborious, and the intensity changes were much more definitely seen than in the elongated form of record. Each syllable had an intensity form, as a 'box,' 'spindle,' 'double spindle,' 'truncated cone,' 'cone,' etc. (cf. p. 446). The disc was run, as a rule, at a rate of about one revolution in two minutes. The rate could be varied to suit the purposes of the experimenter, and it was perfectly possible to procure the usual form of record when desired. As a result of the low rate, the records were exceedingly condensed. The records of the 300 stanzas measured are on two glass discs of about 25 cm. diameter, and as much more could still be recorded on them. The diaphragm and the speaking tube were the great sources of error. For measurements of time values the particular component of the tone to which the diaphragm happens to vibrate is not important, but the record of intensities depends on the fidelity with which the diaphragm responds to a given component, preferably the fundamental, of the tone. The speaking tube has a resonance of its own which can be but partly eliminated. For the records here recorded either glass or goldbeater's skin was used as a diaphragm. Goldbeater's skin has the advantage of being very sensitive, and it must be used if the subject has not a resonant voice. It has the great disadvantage of being extremely variable. It is very sensitive to moisture, even when kept as loose as possible, and cannot be depended on to give the same results from day to day. The records marked Hu., Ha. and G. were usually taken with a glass diaphragm, which has the advantage of being invariable. As the phonograph records show, glass does not modify the lower tones of the male voice to any extent. [Illustration: PSYCHOLOGICAL REVIEW. MONOGRAPH SUPPLEMENT 17. PLATE X. Opposite p. 436. The apparatus is shown arranged for taking parallel records on the smoked glass disc, and on the cylinder of the graphophone. On the left is shown the microscope with which the records on the glass disc were measured. ] The speaking-tube used was of woven material, not of rubber, and a pad of felt was kept in the tube near the diaphragm box. As far as possible more damping was used at the other end of the tube, but this had to depend on the voices of the subjects. The best check on the performances of a diaphragm is the number per second and character of the vibrations. The pitch may be calculated from the rotation rate of the disc, which is very constant, as it is driven at a low rate by the well-regulated high-speed motor of the phonograph. But it is better to place a fork in position to write on the disc and take a parallel record. All the records were taken with the vowel 'a' (sound as in father). This vowel has a very characteristic signature, which is easily seen, even in a very closely packed curve, and the correctness of this is one of the best guarantees that the fundamental of the tone is actuating the diaphragm (though that does not mean that the diaphragm is actually giving the vibration frequency of that fundamental). Every record was repeated at least twice, and both records were measured. In many of the experiments the intensities were fixed by the conditions of the experiment. There was always the corroborative testimony of the phonograph diaphragm; for the two were not apt to err together. It was easy to determine if the actual intensity relations were preserved in the phonograph (but it could not be taken for granted). Each record was reproduced on the phonograph immediately after it had been taken, and both subject and operator listened for anomalies. In practice it was not hard to get records of the single vowel used (at a small range of pitch which was never more than a third or fourth and was nearly always much less) which represented fairly well the relative intensities. Beside the checks spoken of above, every record was repeated by a number of subjects, and the comparison of the results of different voices shows uniformity. The recording of spoken verse is another matter. It is not difficult to test a diaphragm carefully through a small range, but to be certain of its action at all the pitches and qualities of the speaking voice is impossible. A stable diaphragm, glass or mica, would have to be used, and careful corrections made for the different vowels. At best, when the records are satisfactory, nothing can be said for the measurements of intensity but that they represent relations of more or less; the diaphragm has a minimum intensity, below which it does not vibrate, and a maximum intensity, above which the amplitude of its vibrations does not materially increase without breaking into partials and 'blasting.' The disc recorder, which had for a mount a modified microscope stand, was placed on the shoe of the disc stand and clamped. The wax and disc records were adjusted at known starting-points and the stylus carefully lowered, by the rack and pinion adjustment, to the surface of the disc. After a preliminary trial of the diaphragm the apparatus was started, and when at full speed at least two satisfactory records of the material were taken. When the disc had made a single revolution--a record of some ten or fifteen stanzas--the recorder was fed inward to a new circle on the disc. After the records were taken, a microscope with either 2 or 4 Leitz objective and a micrometer ocular was substituted for the recorder. The phonograph recorder was raised and drawn back to its starting point, and the disc came back to its original position. The microscope was focussed, and adjusted by the screw of the shoe until it had the record line in its field; the micrometer furnished an object of reference in the field. The phonograph, now carrying the reproducer--if possible without a horn, as the tones are truer--was started. At the first syllable of the record the apparatus was stopped by the device furnished on the 'Commercial' phonograph, and the plate was turned by adjusting the screw at the phonograph carriage, which changed the length of the chain connecting the two records, until the record of the first syllable was at some chosen point in the field. In cases of records of poetry it was found better to have a set of syllables, say 'one, two, three' prefixed to the record, for this adjustment. The phonograph was again started, and the curve-forms representing the spoken syllables filed past the point as the phonograph repeated each syllable. The rate was slow enough, with the objective 2, so that there was no difficulty in observing the passing syllables. After the conformity of the phonograph record had been noted by the operator, and the subject had passed judgment on the phonograph as saying satisfactorily what he had said, the curve-forms were measured with the micrometer. The record was fed slowly through the field by means of the chain screw on the phonograph carriage; and measurements of the lengths of syllables gave their time values. The micrometer was passed back and forth across the form by the shoe screw, for the measurements of amplitude (intensity). The micrometer measurements in this case could be made at least as rapidly as measurements of kymograph curves. The measurements, with the powers used, are accurate to.01 sec. The smoked disc records are to be preferred to those scratched with a diamond, because of the superior legibility of the line, an important item if thousands of measurements are to be made. The records are fixed with shellac and preserved, or they may be printed out by a photographic process and the prints preserved. The parallel set of wax records is preserved with them. There are several ways in which the wax records lend themselves to the study of rhythmic questions. It is easy to change the rate, and thereby get new material for judgment, in a puzzling case. Consonant qualities are never strong, and it is easy so to damp the reproducer that only the vowel intensities are heard. The application in the study of rhyme is obvious. All the series consisted of regular nonsense syllables. The accented and unaccented elements were represented by the single syllable 'ta' ('a' as in father). Rhymes were of the form 'da,' 'na,' 'ga' and 'ka.' In other parts of the work (cf. Table IV.) the vowel o had been used in rhymes for contrast; but the same vowel, a, was used in these records, to make the intensity measurements comparable. The records of the measurements were as complete as possible. The sonant and the interval of each element were measured, and all the pauses except the stanza pause were recorded. The intensity of each syllable was recorded beneath the length of the syllable, and notes were made both from the appearance of the curve and from the phonograph record. _2. The Normal Form of Unrhymed Verse._ To determine the influence of a subordinate factor in rhythm such as rhyme, it is necessary to know the normal form of verse without this factor. It is natural to assume that the simplest possible form of material would be individual feet recorded seriatim. But on trial, such material turned out to be very complex; the forms changed gradually, iambs becoming trochees and trochees changing into spondees. It is very probable that the normal foot occurs only in a larger whole, the verse. To corroborate the conclusions from perceived rhythms as to the existence of variations in earlier and later parts of the verse, a table of mean variations was prepared from the material recorded and measured for other purposes. TABLE VI. MEAN VARIATIONS. Iambic tetrameters; variations of each element from the average foot of the entire stanza. [Label 1: Unaccented Element of Foot.] [Label 2: Accented Element of Foot.] [Label 3: Percentage M.V. of Unac. El.] [Label 4: Percentage M.V. of Ac. El.] Hu. 8 stanzas [1] [2] [3] [4] M.V. 1st foot 0.9688 1.3125 11.1 7.8 2d " 0.8125 0.6563 9.3 3.9 3d " 0.8438 1.1875 9.7 7.1 4th " 0.9688 11. Av. foot of all stanzas 8.69 16.88 Geo. 10 stanzas, no accents or rhymes within the verse: M.V. 1st foot 2.725 2.775 24.6 13.3 2d " 1.300 1.325 11.8 6.4 3d " 1.400 2.050 12.7 9.8 4th " 2.750 24.9 Av. foot of all stanzas 11.05 20.85 Geo. 8 stanzas, accents and rhymes within the verse: M.V. 1st foot 1.4843 2.4687 13.1 11.5 2d " 1.4219 2.6875 12.6 12.6 3d " 1.7031 2.5312 15.1 11.8 4th " 1.8594 16.4 Av. foot of all stanzas 11.31 21.38 The last element has the 'finality-form' and is not comparable to the other accented elements and therefore is not given. Dactylic tetrameters (catalectic); variations of each element from the average foot of the entire stanza: [Label 1: Accented elements of Foot] [Label 2: 1st Unaccented element of Foot] [Label 3: 2d Unaccented element of Foot] [Label 4: Percentage M.V. of Ac. El.] [Label 5: Percentage M.V. of 1st Unac. El.] [Label 6: Percentage M.V. of 2d Unac. El.] [1] [2] [3] [4] [5] [6] Me., Ha., 8 stanzas, normal: M.V. 1st foot 1.6875 1.2813 1.8125 9.70 9.76 10.5 " 2d " 1.0613 1.0613 1.4061 6.1 8.0 8.1 " 3d " 1.6875 1.3125 1.3750 9.7 9.9 7.9 Av. foot 17.38 13.18 17.31 Geo. 4, stanzas, abnormal type of dactylic foot: M.V. 1st foot 1.5000 1.1250 1.2813 11.5 11.0 8.7 " 2d " 1.5625 1.1250 1.1250 12.0 11.0 7.6 " 3d " 1.3437 1.1873 0.8737 10.3 11.5 5.9 Av. foot 13.00 10.25 14.75 Me., Ha., G., Hu., Am., accent on 2d foot, 8 stanzas: M.V. 1st foot 2.4688 1.3125 2.2813 12.7 12.7 11.5 " 2d " 2.3750 1.1250 3.8438 12.2 8.7 19.3 " 3d " 2.9688 1.3750 2.2500 15.5 10.7 11.3 Av. foot 19.44 12.88 19.88 Me., Ha., G., Hu., 19 stanzas, normal: M.V. 1st foot 1.9474 1.2500 2.2763 10.8 8.6 11.4 " 2d " 1.3816 1.2369 1.7766 7.7 8.5 9.3 " 3d " 1.3158 1.2105 1.6382 7.3 8.4 8.6 Av. foot 18.00 14.24 19.05 Me., Ha., G., 6 stanzas, normal: M.V. 1st foot 2.0000 1.2083 1.8750 10.5 10.4 10.7 " 2d " 2.6250 1.0416 2.1666 13.8 9.1 12.3 " 3d " 2.1250 1.3333 1.3333 11.3 11.4 7.6 Av. foot 18.92 11.58 17.50 The last foot (catalectic) is not comparable in these dactylic stanzas. The mean variations of the table (Table VI.) were calculated as follows: The average for all the elements of the stanza was obtained and an average foot constructed (excluding the last sonant and the pause of the verse). From this average foot the variations of all the first feet were computed, then the variations of all the second feet, etc. Then the variations of the first feet of the stanza were averaged and percentages taken, etc.; it is this last value which goes to the making up of the tables. In inspecting the averages the corresponding elements of the feet should be compared. Any increased length due to a prescribed accent within the verse, etc., appears in the averages as a corresponding increase in the mean variation at that point, and only the first and last feet can be compared as to the variations in the verse as a whole. In making up the tables the material was grouped, not by combining the records of each subject, but by combining all the stanzas of a single type, in order to eliminate individual peculiarities. TABLE VII. Verse pauses in unrhymed stanzas, together with the foot pause within the verse. Length of last foot, together with the average foot within the verse: Average first Last foot Average of first Verse Pause. 3 feet of verse. of verse. 3 foot pauses of verse. Iambs: 36 56.5 24 45.5 57 122 35 100 68.5 125 45 102 63.5 111.5 42 93 63.5 117.5 39 93.5 66 135 42 110 53.5 59 40 45 60 76 45 61 56.5 68 41 54 55.5 56 39 41 53 53.5 37 41.5 56 73 34 45 85 98 56 54 39 50 26.5 36 37 43 17 30 42.5 45 28 30 38.5 49 26 36 40 79 26 55 31 72.5 21 55 33 66 23 54 33 76 22 64 Dactyls, catalectic: 56 63 (The pauses cannot be 60 62 compared because of the 55 66 omission of elements in 51.5 76 the final foot.) 37 40 55 58.5 53 59.5 40 73 38 65 37.5 56 37 73 Throughout the series of measurements made the accented element was nearly always longer, and in no case did the accent fail to increase the length of the sonant. Ebhardt's suggestion that there are two significant parts in each foot-element, viz., sonant and pause, does not seem good. Although the sonant is much longer when accented, the ratio between the sonant and the following interval is not definite. An examination of thirty-two stanzas of unrhymed iambic and dactylic (catalectic) tetrameters (cf. Table VII.) shows that the verse pause is always at least one fourth larger than the foot pause. In the unrhymed stanzas the verse pause varies widely, and may be as large as three times the foot pause. A pause longer than the foot pause is absolutely essential to the unity of the verse. All sorts of ratios are presented; evidently the verse pause is not a function of the foot pause. The next table (Table VIII.) shows a variety of different dynamic shadings in the verse. It is noteworthy that in these nonsense verses the type is uniform throughout the stanza. Representing the intensities by curves similar to those used by the subjects in listening to rhythms, we have the forms shown in Fig. 6 (_a_). The general curve is like that in Fig. 6(_b_). [Illustration: FIG. 6.] When a special emphasis is prescribed on some particular accent in the verse, the type becomes invariable, not only in each stanza, but for all stanzas of all subjects. The records show that the accent is produced in a variety of ways. One, for example, gets the accent by a slight increase in intensity, but especially by a pause following the sonant. TABLE VIII. THE INTENSITY RELATIONS WITHIN THE TOTAL, UNRHYMED VERSE. UNRHYMED IAMBIC TETRAMETERS. Average Intensities. length Length ' ' ' ' of first of last _ - _ - _ - _ - 3 sonants. sonant. Ha. 2 5 4 5 2 4 3 6 31 31s 4 4 2 4 2 5 3 7 33 36s 2 5 3 4 1 5 3 9 32 29s 2 4 2 5 2 5 3 7 31 22s 3 5 1 5 3 4 3 5 37 35s 2 5 2 4 2 4 3 6 35 27s 2 4 2 4 2 4 2 6 38 22s 1 4 3 4 1 5 3 6 34 23s Hu. 6 6 6 6 6 6 6 5 25 33 5 5 5 5 5 5 5 6 26 32 5 5 5 4 5 5 5 5 19 33 5 5 5 6 8 9 8 9 28 50 9 9 8 9 9 9 9 8 43 51 9 7 8 7 7 8 9 10 48 45s 6 7 7 7 6 7 6 7 43 43s 6 6 5 6 4 7 7 8 36 50 G. 9 14 7 14 4 12 6 10 20 25 7 12 7 14 7 10 6 10 16 26 7 12 6 11 4 12 5 10 17 26 6 13 6 11 1 9 7 12 16 26 10 8 7 30 6 15 7 16 18 25 7 14 8 12 6 15 10 13 15 28 7 16 9 15 4 14 7 12 16 25 7 15 7 13 5 13 6 12 17 25 In verses marked 's' the last sonant is shorter than the average of the preceding sonants. UNRHYMED IAMBIC TETRAMETERS: PRESCRIBED ACCENT ON THE THIRD FOOT. ' \/ -- \/ -- \/ -- \/ -- Mc. Couplets. 4 6 6 7 4 6 4 4 5 8 5 6 2 12 8 5 4 6 5 10 4 11 5 3 4 6 5 10 4 10 4 4 7 11 5 9 9 15 5 5 5 19 20 22 21 24 6 6 12 22 16 22 20 22 8 7 12 22 14 31 10 26 6 7 Ha. Couplets. 4 7 4 8 8 9 5 7 5 7 4 6 6 8 2 7 2 6 2 6 5 6 3 6 2 7 3 6 2 10 3 4 3 7 3 7 4 6 4 6 4 5 3 6 4 7 2 6 5 7 1 6 4 8 2 5 2 7 3 5 3 7 2 6 UNRHYMED IAMBIC TETRAMETERS: PRESCRIBED ACCENT ON THE SECOND FOOT. ' \/ -- \/ -- \/ -- \/ -- Mc. Couplets. 13 22 22 30 22 18 15 18 11 20 22 26 15 19 15 10 10 25 20 26 20 24 12 23 10 19 17 26 19 11 9 10 12 23 18 26 22 17 10 15 8 23 20 27 16 22 15 16 12 23 26 30 22 21 10 17 14 28 26 34 11 28 11 21 Ha. Couplets. 6 9 4 12 4 5 3 4 5 4 12 1 5 2 5 3 5 3 12 2 5 2 6 1 6 4 15 1 6 2 7 - 15 3 12 - 8 - 5 - 6 4 12 - 7 - 5 - 7 - 7 4 13 - 4 - 6 3 13 - 5 - 4 G. Couplets. 9 19 11 20 4 12 3 10 5 13 6 16 5 10 6 11 8 16 10 18 5 10 6 11 6 12 6 16 6 10 6 10 8 16 13 19 5 13 8 12 9 17 11 19 3 10 6 12 9 16 9 18 6 10 7 9 7 15 7 15 5 10 5 10 Frequently the special accent seems to be made by a contrast between the accented foot and the feet which follow. In most cases the influence of the special accent is to be seen, not merely within the accented foot itself, but both before and after the accented foot. Often the appearance under the microscope is very striking; the sonants of the feet, both accented and unaccented, increase to the special accent and then decrease in a regular crescendo--diminuendo form. Much of this is not shown by the mere measurements. [Illustration: FIG. 7] [Illustration: FIG. 8 Iambic Tetrameter Verse (with the accent on the second foot)] In general the special accent may he said to be the climax of the verse movement. It is the crest of the wave, and, as noted above, the dynamic shading is not always made by an increase up to the accent, nor by a stress on a special accent, but by a sharp diminuendo immediately following the accent. A study of the phonograph record brings out these forms of shading, especially when the record is repeated slowly, exaggerating the dynamic variations and giving an opportunity for more careful observation. Within the verse the general form of the syllable as it appears in the mass of closely written vibrations, often varies, but nearly always shows a square end. Several very common shapes are noticed and appear in the record as (1) 'truncated cones,' (2) 'boxes,' and (3) 'truncated spindles.' (See Fig. 7.) With the particular syllable used, 'ta,' the beginning of curve form was usually square and abrupt (4), and not gradual (5), although a few of the latter type are found ('spindle'). One syllable form has an especial interest, because of its bearing on the problem of 'finality' feeling at the close of the verse. At the close of each verse, whether with or without rhyme, the syllable form is always a 'cone' (6) (cf. Fig. 8). Of about 600 verses measured not more than 15 are exceptions to this rule. Of these 15 exceptions 10 are under special conditions and confirm the hypothesis that this form is related to the finality process. The form very rarely occurs within the verse, and when it does it is usually before some cæsura, or under unusual conditions. This 'cone' form of the closing syllable of the verse indicates a falling of the intensity of the voice. It is often, though not always, associated with a fall in the pitch, showing relaxation of the vocal cords. It seems to be an indication of the dying out of the intensity factor, a sinking of the tension, at the close of the verse. In the case of unrhymed verses, with long verse pause, the cone is often very much elongated, and it is quite impossible to say where the sound ceases. Special accentuation of the long syllable of the foot increases the length of the sonant, of the accented element, and of the entire foot. There is probably a slight increase of the total length of an accented verse as compared with the similar unaccented, but no calculations were made to show that point. This is quite in accord with other results (Meumann, Ebhardt). This special accentuation is connected with an increased mean variation of the time values, as noted above. It is in that sense a 'disturbing factor.' TABLE IX. VERSE PAUSES (INCLUDING FINAL SONANT) TOGETHER WITH THE AVERAGE OF THE CORRESPONDING ELEMENT WITHIN THE VERSE. Average long Verse pause Verse pause Verse pause element of of 1st verse of 2d verse of 3d verse first 3 feet. of stanza. of stanza. of stanza. End Rhymes. Mc. 26 34 104a 35 45 _45_a 80b 80a 31 33 64a 36 41 52a 51b 75a Ha. 41 _44_a _44_ 45a 43 47a _43_b 46a 39 _41_a 49b 46a 43 46a _45_b _45_a 36 44 41a 53 35 44a 58a 38b 33 40 73a ×30 Hu. 28 ×25a 50 28a Feminine Rhymes. Hu. 18 21a 37a 19b 19 _20_a 22a 16b 19 _21_a _21_a 16b Mc. 36 72a 64 51a 36 ×32 41a 40 22 _22_a ×18 29a Ha. 27 31a 44b _28_a 36 79 ×30 40 30 36 79a _30_b 31 38 50a 36 32 39a 42 40a Am. 34 70 95a 85 35 73a 94 89a 30 45 47a 86 28 54 53a 70 G. 19 64a 64 79a 19 73a 83b 76a 21 81 67a -- 19 61 83a 79 The rhymes are marked 'a' and 'b'; _e.g._, couplets a, a, b, b, etc. Verse pauses in italics are equal to the foot pause; those marked 'x' are _less_ than the foot pause. 3. _Modification of the Normal Form of Verse due to Rhyme._ Verse Pause in Rhymed Material. There are as wide, isolated variations as in the case of unrhymed material. As compared with unrhymed verse, the pause is in general decidedly shorter. The verse pauses of the feminine rhymes are generally much like those of the end rhymed material. But there are very few cases of the verse pause being as short as the foot pause--only four cases in sixty (6.6 per cent.). See Table IX. This wide variation of the verse pause and its occasional equivalence to the foot pause in rhymed verses is in accord with the notion that the rhyme in some way brings the verse to a close by a process more rapid than that in unrhymed material. The introduction of rhyme seems to be favorable to the division of a stanza into two parts by producing an unusually long verse pause after the second verse. Of 43 unrhymed stanzas there are 19 which show a decidedly long pause at the close of some one of the verses. But of these 19 cases, only 8 (18 per cent.) have the break at the close of the second verse. Of 64 rhymed stanzas, 29 show the division, and of this 29, 22 (34 per cent.) have the break at the close of the second verse. Influence of the Rhymes on Intensities. The intensities at the close of the verse, without rhyme, may be slightly greater than within the verse. The dynamic shading of the verse is elastic, and a variety of forms is possible, a decrescendo at the close of the verse is not unusual (cf. Table VIII.). But when the rhyme is introduced the general dynamic form of the verse is fixed, and in the material measured this is true not only of the verses in a stanza which contain the rhyme but of other verses in the same stanza. Of the 32 verses containing rhymes in Table X., but four verses are exceptions to the rule of an increase of intensity on the rhyme. There are two cases of double, alternating rhymes where it is doubtful if the subject actually felt one of the alternating rhymes. This increase of intensity on the rhyme is not confined to that particular syllable or foot; often, as indicated by the italics, the influence of the accent makes itself felt earlier in the verse. TABLE X. INTENSITIES OF IAMBIC TETRAMETER WITH END RHYME (SHOWING INCREASED INTENSITY OF THE RHYMING SYLLABLE). ALSO AVERAGE LENGTH OF THE FIRST THREE SONANTS, TOGETHER WITH THE LENGTH OF THE LAST SONANT. Intensities. Average length of first 3 Length of last sonants. sonant. \/ - \/ - \/ - \/ - Mc. -- 5 -- 5 -- 4 -- 5 19 27 -- 4 -- 4 -- 4 -- _11_a 34 -- 4 -- 4 -- 4 -- 7 21 -- 4 -- 5 -- 3 -- _8_a 23 -- 6 -- 6 -- 5 -- 6 19 22 -- 8 -- 7 -- 6 -- _10_a 34 -- 4 -- 3 -- 4 -- 5 26 -- 3 -- 5 -- 4 -- _5_a 30 2 3 5 4 4 5 6 _7_a 29 34 2 3 3 4 2 4 2 _7_b 48 1 2 3 2 2 2 1 _4_a 35 2 3 3 3 2 3 4 _5_b 20 -- -- -- -- -- -- -- --a 25 40 3 4 4 14 3 4 5 _5_b 39 2 3 1 2 2 3 1 _3_a 25 1 3 2 2 1 3 3 _5_b 43 Ha. 6 15 9 12 3 10 4 16 No increase in length. 3 5 3 7 3 5 5 15a 1 15 1 5 4 6 2 9 4 5 2 5 1 5 2 _14_a 2 6 4 8 1 6 5 _11_a No increase in length. 1 7 5 7 3 6 7 _11_b 2 5 2 6 2 6 4 _12_a 1 5 1 5 2 6 3 _15_b 33 38 4 9 5 9 1 3 6 _9_a 25 33 2 8 5 6 4 5 5 _10_b No increase in length. 2 5 2 5 2 5 5 _11_a 1 5 2 5 5 10 2 _12_b 32 34 The evidence of an increased intensity on the rhyme is not so positive in the case of rhymes in the third foot. Among the rhymes in the second foot there is but one exception. The rhymes in the second and third feet were never given very satisfactorily by several of the subjects. The rhymes within the verse determine a climax in the foot in which they occur, and all the verses follow this well-defined type. It is interesting to note, in studying the phonographic record, that in verses in which the accentuation of the rhythm is not very definite, the accentuation is perceived when the record is repeated at the normal speed. If the record is repeated more slowly, and especially at such a distance that the rhyming consonants cannot be distinguished, then the accentuation seems to disappear. It is probable that after a verse or stanza type has been established the voice may deviate from the type, and the accentuation will be supplied by the hearer. TABLE XI. INTENSITIES OF IAMBIC TETRAMETERS WITH RHYMES IN THE THIRD FOOT (SHOWING INCREASE IN INTENSITY OF THE RHYME SYLLABLE). ' ' ' ' \/ -- \/ -- \/ -- \/ -- Ha. 13 18 10 16 _7_ _9_a 6 12 9 10 4 11 7 _14_a 4 7 -- 12 5 10 7 9b 6 9 2 12 5 12 3 _14_b 4 6 2 12 4 13 7 8a 4 9 6 8 4 14 4 _15_a 2 9 2 13 -- 12 8 8b -- -- 5 9 6 10 -- 3b 4 6 Am. 10 10 4 12 6 _14_a 5 5 4 12 6 9 7 8a 4 4 5 12 8 9 7 _10_b 3 4 3 7 5 8 5 7b 2 4 10 13 5 10 4 _10_a 4 6 1 9 4 9 3 5a 3 5 2 8 3 5 -- _8_b 1 5 1 7 2 7 5 _8_b 2 3 G. 6 13 6 13 7 _12_a 1 10 6 10 6 6 _7_ _7_a 1 8 4 9 7 7 _6_ 9b 1 7 7 12 4 10 2 7b 1 7 10 12 4 11 6 _10_a -- 8 5 12 5 11 6 _10_a -- 8 3 9 6 9 _7_ _9_b 3 8 2 8 5 9 5 5b 1 6 D. 10 12 10 10 7 9a 7 11 5 8 6 9 7 7? 6 6 5 12 7 9 6 _10_b -- 8 6 9 7 10 7 7b 5 5 10 15 5 11 6 9a -- 9 5 9 4 8 6 6a? 6 7 7 11 7 11 _11_ _13_b 8 10 8 11 8 10 7 9b 6 8 INTENSITIES OF IAMBIC TETRAMETERS WITH RHYMES IN THE SECOND FOOT. ' ' ' ' _ - _ - _ - _ - Hu. 5 6 6 6a 5 7 5 6 5 6 5 4a 5 4 5 6? 5 6 6 7b 5 6 4 7 5 6 4 4b 5 7 4 7 5 7 7 7a 6 7 6 6 5 7 5 5a 5 6 5 6? 5 7 _6_ 8b 6 7 6 7 6 7 6 5b 6 7 6 7 Mc. 5 7 6 _10a_ 5 4 3 5 1 6 6 _8a_ - 6 1 4 1 6 6 _10b_ 1 4 - 4 - 7 6 5b 3 3 - 3 Ha. 16 14 _8_ _10a_ 6 10 5 9 5 10 7 8a 5 9 5 7 2 8 4 _11b_ 4 7 2 8 2 8 4 6b 1 9 4 8 7 12 7 _10a_ - 10 6 10 3 10 5 8a 5 8 6 10 2 8 3 _11b_ 3 7 3 10 - 7 5 9b 4 8 6 12 Am. 4 9 _9_ _10a_ 4 7 4 5 4 8 _9_ _7a_ 5 7 4 6 1 8 5 _10b_ 4 6 3 6 - 10 _10_ 7b_ 3 5 2 7 15 15 _10_ 13a_ 9 11 - 11 5 12 7 9a 4 10 4 9 5 8 _8_ _9b_ 4 7 - 6 7 8 5 _9b_ 2 4 - 3 G. 2 6 _6_ _8a_ 1 7 2 3 - 10 _7_ _12a_ 1 9 4 8 4 9 _6_ _9b_ 8 8 2 7 - - - -b - - - - 4 9 _5_ _11_a - 7 4 6 - 8 6 7a 2 7 4 5 - 9 _7_ _6_b - 7 3 6 - 7 3 5 - 5 - 3 D. - - - - - - - - 7 11 _11_ _9_a 7 11 6 10 11 15 11 11a 8 11 9 14 6 10 _10_ 8b 7 8 7 11 12 13 10 10a 7 1? 8 11 6 10 9 8a 5 8 5 9 9 12 12 13b 8 10 7 9 7 11 _10_ 7b 4 8 4 8 The values surrounded by '_'s (Transcriber's Note: Original italics) show the increase in intensity. Rhymes are indicated by 'a' and 'b.' IV. SUGGESTIONS FOR A MOTOR THEORY OF RHYTHM. If the basis of rhythm is to be found in muscular sensations, rather than in the supposed activity of some special 'mental' function, the nature of the movement cycle involved is of the greatest interest. In every case where a rhythm comes to peripheral expression, there are two opposing sets of muscles involved. If a rhythmic movement be attempted with but a single set of muscles at work, it is very unsatisfactory and soon ends in the tonic contraction of the muscle set. One may assume that in all cases of rhythm perception there is a cycle of movement sensations involved, and that the simplest possible case of a peripheral rhythmic movement is the type of any rhythm. In tapping a rhythm with the finger, the flexors which bring the finger down become the positive muscle set, and the opposing extensor muscles which raise the finger for the next blow become the negative muscle set. In Fig. 9 the upper curve represents the actual movement of the finger tip, and the heavy lines _a_, _a'_, _a''_ represent the pressure-tension-sound sensation which we call the 'beat,' and which is the limiting sensation of the rhythm, and the regulating factor in the movement cycle of the rhythm. The movement is divided into two phases; _B_, the phase of relaxation, during which the finger is raised, and _A_, the phase of contraction, during which the finger delivers the blow which produces the beat. The curves below represent the changes in the two opposing sets of muscles whose interaction brings about the movement cycle. The contraction of the flexors, the positive muscle set, is represented by the curve above the base line. It is obvious that during the contraction phase, the contraction in the positive muscle set is at its height; it continues at a maximum during the limiting sensation and then dies away during the relaxation phase. The sensations from this positive muscle set have the principal place in consciousness during the rhythm experience. The curve below the base line represents the contraction of the extensors, the negative muscle set. The contraction of the negative muscles reaches its climax very soon after the maximum contraction of the positive muscles, in the contraction phase. The sharp tension between the two opposing sets of muscles at the limiting sensation may be made very apparent if the finger beats the rhythm entirely in the air; in that case the limiting sensation consists entirely of the feeling of a sudden increase of tension between the positive and negative muscle sets. During the relaxation phase the contraction of the negative muscles continues, but the tension between the two sets grows less and less, for the positive muscles are rapidly relaxing. At the highest point in the movement either muscle set is exerting but very little strain; the condition is represented in the figure by the approach of either curve to the base-line; the amount of tension between the two sets is figured by the distance of the two curves from each other. [Illustration: FIG. 9.] Assuming such a movement cycle, in which the tension between the two opposing sets never comes to zero until the close of the series, it is not difficult to arrange many of the facts of rhythmic perception under the motor theory. 1. The feeling of rhythm is more definite as we proceed in a verse, or a series of simple sound sensations. At first the cycle is not perfectly adjusted and complete automatism established. 2. If an observer is listening to a series, and an unusually long pause is introduced between two beats, there is always a feeling of suspense or tension during the 'lag.' As long as the tensions are maintained there is a rhythmic continuity; the feeling of tension is the strain of opposition between the opposing muscle sets. 3. The continuity of the rhythmic series, whereby all the beats of a period seem to belong to a single whole, is due to the continuity of the muscle sensations involved and the continuous feeling of slight tension between the positive and negative muscle sets; nowhere within the period does the feeling of strain die out. 4. But at the close of the period we have a pause which is demonstrably not a function of any of the intervals of the period. During this pause the tension between the two sets 'dies out,' and we have a feeling of finality. This gradual dying out of the tension is clearly seen in the constant appearance of the cone-shaped final syllable at the end of each nonsense verse. 5. The period composed of a number of unit groups (the verse, in nonsense syllables) has a general form which suggests strongly that it has the unity of a single coördinated movement. There is no more reason for assuming a transcendental mental activity in the case of a rhythmic period than in the case of a single act which appears in consciousness as a unity. Undoubtedly the breathing is correlated with the rhythmic movements and may be a factor in determining the verse period. Meumann's principal accent, about which a number of subordinate accents are grouped, is characteristic not only of poetry but of the simplest rhythms. At some point in the period there is a definite climax, a chief accent; the movement 'rises' to that point and then falls off. This is strikingly seen in nonsense verses spoken with a heavy accent within the verse. The accent does not stand out from a dead level, but the verse culminates at that point. Unfortunately very little is known of the mechanism of so simple a coördinated muscular activity as that necessary for a simple rhythm. Sherrington[17] and Hering[18]have pointed out the primary character of the grouping of the muscles in opposing sets and the reciprocal nature of almost all muscular activity, but in a review of the work of coördinated movements Hering denies any simultaneous stimulation of the two sets and considers the question of the innervation mechanism of opposing muscle-sets entirely unsettled. [17] Sherrington, C.S.: _Proceedings Royal Soc._, 1897, p. 415. [18] Hering, H.E.: _Archiv f. d. ges. Physiol._ (Pflüger's), 1897, Bd. 68, S. 222; _ibid._, 1898, Bd. 70, S. 559. That the connection between the positive and negative set of muscles in a rhythmic movement is very close, and that the reaction is of the circular type, is evident from the automatic character of all rhythmic movements, and it is evident that the limiting sensation is the primary cue in the reaction. Anything further is mere hypothesis. Robert Müller's[19] thorough criticism of the Mosso ergograph throws great doubt on the present methods of investigation and invalidates conclusions from the various curves of voluntary movements which have been obtained. [19] Müller, R.: _Phil. Stud._, 1901, Bd. 17, S. 1. The curve of contraction and relaxation of a simple muscle is well known and is not affected by Müller's criticism. Its chief characteristic, with or without opposing tension, is the inequality of the intervals of the contraction and relaxation phases. As one might expect, since a single set of muscles dominates in a rhythmic movement, the typical rhythmic curve has the general character of the curve of the simple muscle. The average values of the phases of curves of simple rhythmic movement obtained by A. Cleghorn[20] from a large number of observations with at least three subjects, are as follows: phase of contraction, .44 second; phase of relaxation, .54 second. It is very significant for a motor theory of rhythm that this general form of the curve of rhythmic movement may easily be altered in all sorts of fashions by unusual stimuli to the two muscle sets. [20] Cleghorn, A.: _Am. Journal of Physiol._, 1898, I., p. 336. While it is well recognized that a rhythm does not consist necessarily of sound sensations, the 'rhythmization' of a series of sound sensations in the ordinary perceived rhythms is a matter of great interest. Ewald found strong reasons for believing that the ear is peculiarly connected with the motor apparatus. The experiments of Hofbauer[21] and Cleghorn[22]show that any strong stimulus to either eye or ear modifies decidedly the reactions of coördinated muscles. How shall we assume that the automatic movement cycle necessary to rhythmic perception is set up when one listens to a series of sounds? [21] Hofbauer: _Archiv f. d. ges. Physiol._ (Pflüger's), 1897, Bd. 68, S. 553. [22] Cleghorn, A.: _op. cit._ It must be assumed that any chance sound sets up a contraction in a set of muscles, however large or small. If but a single sound occurs, the phase of contraction in that muscle set is followed by a longer phase of relaxation, and the musculature is passive as before; it may be that the stretching of the antagonistic set of muscles weakly stimulates them, and they then contract during the relaxation phase and assist in restoring the original condition. But if a second sound occurs toward the end of the relaxation phase, before the tension is quite exhausted, the movement will be repeated; the negative set of muscles will be more definitely stimulated, for the activity will not have been exhausted when the second sound occurs. If the sound continues to recur at regular intervals, the movement cycle thus established will rapidly become coördinated. The positive set in its vigorous contraction furnishes a limiting sensation which becomes a cue for its own relaxation and for the reciprocal contraction of the negative muscle set. The contraction of the negative muscle set and the resulting changes in tension may become in turn a cue for the positive set. The reaction is now of the circular type and the process has become self-regulative, though constantly reinforced by the recurring sound (which has become a part of the limiting sensation of the rhythmic movement cycle). But it is very probable that the second sound may not be timed so as to come at the close of the relaxation phase in the set of muscles roused; moreover, in almost all rhythms there are secondary sounds occurring between the main beats. What happens when a sound occurs out of place, early in the phase of relaxation, or just before or just after the climax in the contraction phase? Does it make it impossible to establish the coördination, or destroy it if already established? Hofbauer demonstrated that a stimulus which appears in close proximity to the limiting sensation, _either before or after_, always increases the force of the reaction, so that such a slight displacement could not affect the rhythm, which would quickly readjust itself. The possibility of a stimulus occurring in the relaxation phase is of much more importance for a motor theory of the initiation of a rhythmic movement. Cleghorn made the stimulus occur at the beginning of the relaxation phase. Instead of prolonging or reinstating the contraction phase, he found that the stimulus _intensified the relaxation process and shortened its period_. "The stimulated relaxation is not only quicker than the normal, but also more complete; the end of the normal relaxation is slow; ... relaxation under the influence of the stimulus, on the contrary, shows nothing of this, but is a sudden sharp drop directly to the base line and sometimes below it." A comparison of the normal phases with the same phases, when the stimulus occurs within the relaxation phase, follows: Normal: Contraction-phase, .44 sec.; relaxation-phase, .54 sec.; total, .98 sec. With stim.: Contraction-phase, .47 sec.: relaxation-phase, .30 sec.; total, .77 sec. It will be noticed that the total time of the movement cycle is reduced. One may then assume that a sound which occurs too early to become a factor in the limiting sensation, functions as a stimulus to the relaxation process and shortens the interval between the limiting sensations. Thus the movement cycle would be modified, but not destroyed. It is impossible to say just how the relaxation process is affected, and Cleghorn's own conclusions are open to criticism in the light of Müller's comments on the method. The simplest assumption would be that the stimulus acted on the negative set of muscles. E.W. Scripture[23] objects to such a 'tonus theory,' because some subjects regularly react _before_ the signal. But in no case in the published records to which he refers is the error more than.05 sec. either before or after the signal. The investigation of Hofbauer shows conclusively that in such cases the effect of the external stimulus simply fuses with the limiting sensation. Scripture overlooks the automatic character of the rhythmic movement. [23] Scripture, E.W.: 'The New Psychology,' London, 1897, p. 182. There is a striking difference between rhythmic movement from unit group to unit group within a period, and movement from period to period (_i.e._, from verse to verse of nonsense syllables). Each foot is simply the repetition of the movement cycle; all the tensions are maintained, and each foot is an integral part of a larger act. At the close of the period (verse) the active tensions die out, either because of the introduction of some unusual stimulus which causes the positive muscle set to strike a heavy blow, and abruptly upset the balanced tensions, or because a pause of indefinite length ensues in which the tensions die out. This is the process which we call 'finality.' In the stanza there is evidently a different type of unity from that in the single verse. When we hear the first verse of the stanza, we do not know what the verse whole is, until the finality factor or the verse pause is reached, at its close. Then the verse has a certain definite cumulative effect, a synthetic effect which results from the echoes of the various movements and the total effect on the organism. One may call it the tetrameter feeling. The verse pause may vary within large limits, but after a few verses there is a definite scheme, or 'Gestaltqualität,' which represents the verse unity. It is some sort of a memory image, which functions as a cue to the motor process. This motor image, set of strains, or whatever it be, is more than a mere standard by which we judge the present verse. The memory image fuses in some way with the living motor process. _The preceding verse affects the character of the following verse._ An irregularity, easily noted in the first verse, is obscure in the second, and not detected in the third verse, when the verses are identical. The experiments of Hofbauer and Cleghorn, and many facts about the unit groups themselves, make it evident that the function of stimuli, during the movement cycle, varies with the position of the stimulus in that cycle. This offers a possible explanation of the striking peculiarities of the unit groups. The iamb [\/ _'] and the trochee [_' \/] should be quite alike for a general synthesizing process; but not only is the experiential character of the two quite unlike, but the ratio between their intervals is entirely different. A number of measurements by different observers show that in the iambic foot the unaccented syllable is proportionately much shorter than the unaccented syllable in the trochaic foot. It is very easy to beat a simple up-and-down accompaniment to a series of simple feet of nonsense syllables; in the accompaniment the bottom of the down stroke, the limiting sensation of the movement cycle, coincides with the accented syllable of the foot. It is not an unwarranted assumption that such a fundamental accompaniment represents the fundamental movement cycle of that rhythm. During the present investigation several observers were asked to determine at just what point in the fundamental movement the unaccented syllable occurred, when the subject gave a series of nonsense syllables. In the fundamental accompaniment the excursion of the hand and arm was at least.4 meter. Four subjects were thus tested, and the results were uniform in the case of all the simple types of unit groups. In the case of the iamb the unaccented syllable occurs at the top of the movement, at the very beginning of the contraction phase (A, in Fig. 5). In the case of the trochee the unaccented syllable occurs in the first third of the relaxation phase (B). It is interesting to note that the unaccented element of the trochee comes at the earlier part of the relaxation phase, where it must intensify the relaxation process, and tend to shorten the total length of the cycle. This may be the reason for its peculiar buoyant, vigorous and non-final character. On the other hand the unaccented element of the iamb occurs at a point where it may initiate and intensify the contraction, which gives the limiting sensation; it is, therefore, more closely bound to the limiting sensation, and has the character of intensifying the beat. There is a similar contrast in the cases of the dactyl and anapæst. The accented syllable of the dactyl is longest, and the second unaccented syllable, the last in the group, is shortest. The accented syllable of the anapæst is much longer in proportion than that of the dactyl, and the unaccented syllables are very short, and hence, very close to the accented syllable, as compared with the dactyl. In the case of the dactyl the first unaccented syllable in the movement cycle occurs at the beginning of the relaxation phase (B), in the same zone as the unaccented of the trochee. The second unaccented syllable of the dactyl appears at the beginning of the next contraction phase (A), in the zone of the unaccented syllable of the iamb. The group seems a sort of combination of the iamb and trochee, and has an element in every possible zone of the movement cycle. Like the trochee the dactyl is a non-final foot. The unaccented syllables of the anapæst both occur at the beginning of the contraction phase (A). They are both within the zone of the unaccented syllable of the iamb. The group seems an iamb with a duplicated unaccented syllable. It is possible to form a unit group in nonsense syllables where the unaccented syllable of the iamb shall be represented not by two syllables, as in the anapæst, but by even three. The anapæst and dactyl, if they correspond to this construction, should show a decided difference as to the possibility of prolonging the foot pause. The prolongation of the foot pause would make the dactyl but a modified trochee. It is significant that in poetry no other types of unit groups are often recognized. The amphibrach, laid out on this scheme, would coincide with the dactyl, as there are but three possible zones for foot elements: the zone of the limiting sensation (always occupied by the accented syllable), the zone of the contraction phase (occupied by the unaccented syllables of the iamb and anapæst), and the zone of the relaxation phase (occupied by the unaccented syllable of the trochee and the middle syllable of the dactyl). The simple sound series is fairly regular, because of its cyclic and automatic character. It is not a matter of time estimation, and the 'Taktgleichheit' is not observed with accuracy. The primary requisite for the unit groups is that they shall be _alike_, not that they shall be _equal_. The normal cycle with a heavy accent is longer than the normal cycle with a lighter accent, for the simple reason that it takes muscles longer to relax from the tenser condition. Time is not mysteriously 'lost'; the objective difference is not noticed, simply because there are no striking differences in the cycles to lead one to a time judgment. Ebhardt's notion that the motor reaction interferes with the time judgment, and that a small amount of time is needed in the rhythmic series in which to make time judgments, is a mere myth. An unusual irregularity, like a 'lag,' is noted because of the sense of strain and because other events supervene in the interval. But such lags may be large without destroying the rhythm; indeed cæsural and verse pauses are essential to a rhythm, and in no sense rhythm-destroying. An unbroken series of unit groups is an abstraction to which most forms of apparatus have helped us. Between the extreme views of Bolton[24] and Sidney Lanier,[25]who make regularity an essential of the rhythm of verse, and Meumann, on the other hand, who makes the meaning predominate over the rhythm, the choice would fall with Meumann, if one must choose. Bolton comes to the matter after an investigation in which regularity was a characteristic of all the series. Lanier's constructions are in musical terms, and for that very reason open to question. He points out many subtle and interesting relationships, but that verse can be formulated in terms of music is a theory which stands or falls by experimental tests. [24] Bolton, T.L.: _loc. cit._ [25] Lanier, S.: 'The Science of English Verse.' TABLE XII. I saw a ship a sailing 50 16 20 13 9 18 32 23- 132 A sailing on the sea 10 16 45 22 8 15 49 -68 And it was full of pretty things 8 6 20 6 6 27 37 12 8 7 20 12 41 -34 For baby and for me 14 9 27 37 18 20 14 8 46 -- Totals of the feet: --/66/60/187 26/45/45/117 14/59/49/47/75 23/64/60/46-- Who killed Cock Robin 19 34 23 24 17-77 I said the sparrow 45 21 19 3 47 29 -- With my bow and arrow 22 36 25 49 11 38 12 23 33-42 I killed Cock Robin 33 12 33 21 22 5 21 16-95 (The first stanza was measured in the Harvard Laboratory. The last is modified from Scripture's measurements of the gramophone record (1899). As the scansion of the last is in doubt with Scripture, no totals of feet are given.) In the cases given in the above table there is an irregularity quite impossible to music. In the movement cycle of the simple sounds there is a perfect uniformity of the movements of the positive and negative sets of muscles from unit group to unit group. But in verse, the movements of the motor apparatus are very complicated. Certain combinations require more time for execution; but if this variation in the details of the movement does not break the series of motor cues, or so delay the movements as to produce a feeling of strain, the unit groups are felt to be alike. We have no means of judging their temporal _equality_, even if we cared to judge of it. It is a mistake, however, to say that time relations ('quantity') play no part in modern verse, for the phases of the movement cycle have certain duration relations which can be varied only within limits. Extreme caution is necessary in drawing conclusions as to the nature of verse from work with scanned nonsense syllables or with mechanical clicks. It is safe to say that verse is rhythmic, and, if rhythm depends on a certain regularity of movements, that verse will show such movements. It will of course use the widest variation possible in the matter of accents, lags, dynamic forms, and lengths of sonant and element depending on emphasis. The character of the verse as it appears on the page may not be the character of the verse as it is actually read. The verses may be arbitrarily united or divided. But in any simple, rhythmic series, like verse, it seems inevitable that there shall be a pause at the end of the real verse, unless some such device as rhyme is used for the larger phrasing. There is a variety of repetitions in poetry. There may be a vague, haunting recurrence of a word or phrase, without a definite or symmetrical place in the structure. Repetition at once attracts attention and tends to become a structural element because of its vividness in the total effect. There are two ways in which it may enter into the rhythmic structure. It may become a well-defined refrain, usually of more than one word, repeated at intervals and giving a sense of recognition and possibly of completeness, or it may be so correlated that the verses are bound together and occur in groups or pairs. Rhyme is a highly specialized form of such recurrence. The introduction of rhyme into verse must affect the verse in two directions. It makes one element in the time values, viz., the verse pause, much more flexible and favors 'run on' form of verses; it is an important factor in building larger unities; it correlates verses, and contributes definite 'Gestaltqualitäten' which make possible the recognition of structure and the control of the larger movements which determine this structure. Thus it gives plasticity and variety to the verse. On the other hand, it limits the verse form in several directions. The general dynamic relations and the individual accents must conform to the types possible with rhyme. The expressional changes of pitch, which constitute the 'melody,' or the 'inflections' of the sentences, play an important part. The dynamic and melodic phases of spoken verse which have important relations to the rhyme are not determined by the mere words. The verses may scan faultlessly, the lines may read smoothly and be without harsh and difficult combinations, and yet the total rhythmic effect may be indifferent or unpleasant. When a critic dilates on his infallible detection of an indefinable somewhat, independent of material aspects of the verse and traceable to a mystic charm of 'thought,' it may very well be that the unanalyzed thing lies in just such dynamic and melodic conditions of rhythm and rhyme. The most primitive characteristic of music is the _ensemble_. Savage music is often little else than time-keeping. When the social consciousness would express itself in speech or movement in unison, some sort of automatic regulation is necessary. This is the beginning of music. The free reading of verse easily passes over into singing or chanting. When this happens, the thing most noticeable in the new form is its regulated, automatic and somewhat rigid character. It is stereotyped throughout. Not only are the intervals and accents fixed, but the pitch and quality changes are now definite, sustained and recurrent. The whole sum of the motor processes of utterance has become coördinated and regulated. Along with this precision of all the movements comes a tendency to beat a new rhythm. This accompanying rhythm is simpler and broader in character; it is a kind of long swell on which the speech movements ripple. This second rhythm may express itself in a new movement of hand, head, foot or body; when it has become more conscious, as in patting time to a dance or chant, it develops complicated forms, and a third rhythm may appear beside it, to mark the main stresses of the two processes. The negro patting time for a dance beats the third fundamental rhythm with his foot, while his hands pat an elaborate second rhythm to the primary rhythm of the dancers. The essential character of musical rhythm, as contrasted with the rhythm of both simple sounds and of verse, is just this coördination of a number of rhythms which move side by side. This is the reason for the immense complexity and variety of musical rhythms. The processes check each other and furnish a basis for a precision and elaborateness of rhythmical movement in the individual parts which is quite impossible in a simple rhythm. Even when the concomitant rhythms are not expressed, as in an unaccompanied solo, an accompaniment of some sort is present in the motor apparatus, and contributes its effect to the consciousness. This regulation of the movement by the coincidence of several rhythms is the cause of the striking regularity of the temporal relations. At some points in the musical series the several movement cycles may appear in the same phase, and at these points the same irregularities as in verse are possible, as in the case of pauses at the ends of periods and the irregularities of phrasing. It is evident in cases of expressional variations of tempo that a single broad rhythm is dominating and serving as a cue for the other more elaborate rhythmic processes, instead of being regulated by them. * * * * * STUDIES IN SYMMETRY.[1] BY ETHEL D. PUFFER. [1] SOURCES OF ILLUSTRATIONS. Fig. 1 was copied from Reiss u. Stübel, 'Todtenfeld v. Ancou,' Berlin, 1880-1887. Figs. 2, 3, 4, 5, 6, 7, 8 and 11 were copied from the publications of the American Bureau of Ethnology by the kind permission of the Direction. Fig. 9. was copied from A.C. Haddon, 'The Decorative Art of British New Guinea,' Cunningham Memoir, N., Royal Irish Academy, 1894. Fig. 10 was copied from Franz Boas, 'The Decorative Art of the Indians of the North Pacific Coast,' Bulletin of the Am. Mus. of Nat. Hist., Vol. IX. I. THE PROBLEMS OF SYMMETRY. The problem of æsthetic satisfaction in symmetrical forms is easily linked with the well-known theory of 'sympathetic reproduction.' If there exists an instinctive tendency to imitate visual forms by motor impulses, the impulses suggested by the symmetrical form would seem to be especially in harmony with the system of energies in our bilateral organism, and this harmony may be the basis of our pleasure. But we should then expect that all space arrangements which deviate from complete symmetry, and thus suggest motor impulses which do not correspond to the natural bilateral type would fail to give æsthetic pleasure. Such, however, is not the case. Non-symmetrical arrangements of space are often extremely pleasing. This contradiction disappears if we are able to show that the apparently non-symmetrical arrangement contains a hidden symmetry, and that all the elements of that arrangement contribute to bring about just that bilateral type of motor impulses which is characteristic of geometrical symmetry. The question whether or not this is the fact makes the leading problem of this paper, and the answer to it must throw light on the value of the theory itself. An exhaustive treatment of our question would thus divide itself into two parts; the first dealing with real (or geometrical) symmetry, the second with apparent asymmetry; the first seeking to show that there is a real æsthetic pleasure in geometrical symmetry, and that this pleasure is indeed based on the harmony of the motor impulses suggested by symmetry, with the natural motor impulses of the human organism; the second seeking to show in what manner æsthetically pleasing but asymmetrical arrangements conform to the same principles. Within these two groups of problems two general types of investigation are seen to be required; experiment, and the analysis of æsthetic objects. The main question, as stated above, is of course whether the theory can explain our pleasure in arrangements which are completely or partly symmetrical. It is, however, an indispensible preliminary to this question, to decide whether the pleasure in symmetrical arrangements of space is indeed immediate and original. If it were shown to be a satisfaction of expectation, bred partly from the observation of symmetrical forms in nature, partly from the greater convenience of symmetrical objects in daily use, the whole question of a psychophysical explanation would have no point. If no original æsthetic pleasure is felt, the problem would be transformed to a demand for the explanation of the various ways in which practical satisfaction is given by symmetrical objects and arrangements. The logical order, then, for our investigation would be: First, the appearance of symmetry in the productions of primitive life, as a (debatable) æsthetic phenomenon emerging from pre-æsthetic conditions; secondly, the experimental study of real symmetry; thirdly, the analysis of geometrical symmetry in art, especially in painting and architecture, by means of which the results of the preceding studies could be checked and confirmed. Having once established a theory of the æsthetic significance of real symmetry, we should next have to examine asymmetrical, beautiful objects with reference to the relation of their parts to a middle line; to isolate the elements which suggest motor impulses; to find out how far it is possible to establish a system of substitution of these psychological factors and how far such substitution takes place in works of art--_i.e._, to what extent a substitutional symmetry or balance is found in pleasing arrangements. These investigations, again, would fall into the two groups of experiment and analysis. The products of civilized art are too complicated to admit of the complete analysis and isolation of elements necessary to establish such a system of substitution of psychological factors as we seek. From suggestions, however, obtained from pleasing asymmetrical arrangements, first, isolated elements may be treated experimentally, and secondly, the results checked and confirmed by works of art. With regard to the study of objects without a natural or suggested middle line, as for instance sculpture, many types of architecture, landscapes, gardens, room-arrangements, etc., we may fitly consider it as a corollary to the study of asymmetrical objects with artificial limits which do suggest a middle. If we find, by the study of them, that a system of substitution of psychological factors does obtain, the whole field can be covered by the theory already propounded, and its application extended to the minutest details. The hypothesis, having been so far confirmed, may be then easily applied to the field of asymmetrical objects without a natural middle line. The set of problems here suggested to the student of symmetry will not be fully followed out in this paper. The experimental treatment of geometrical symmetry, the analysis of the completely symmetrical products of civilized art, and the analysis of all forms of asymmetry except asymmetry in pictures will be omitted. If, however, the fact of an original æsthetic feeling for symmetry is established by the study of primitive art, and the theory of the balance of motor impulses through the substitution of factors is established by the experimental treatment of isolated elements, and further confirmed by the analysis of pictures, the general argument may be taken as sufficiently supported. This paper, then, will contain three sections: an introductory one on symmetry in primitive art, and two main sections, one on experiments in substitutional symmetry, and one on substitutional symmetry or balance in pictures. II. SYMMETRY IN PRIMITIVE ART. The question which this section will attempt to answer is this: Is there in primitive art an original and immediate æsthetic feeling for symmetry? This question depends on two others which must precede it: To what extent does symmetry actually appear in primitive art? and, How far must its presence be accounted for by other than æsthetic demands? For the purpose of this inquiry the word _primitive_ may be taken broadly as applying to the products of savage and half-savage peoples of to-day, as well as to those of prehistoric races. The expression _primitive art_, also, requires a word of explanation. The primitive man seldom makes purely ornamental objects, but, on the other hand, most of his articles of daily use have an ornamental character. We have to consider primitive art, therefore, as represented in the form and ornamentation of all these objects, constituting practically an household inventory, with the addition of certain drawings and paintings which do not appear to serve a definite practical end. These last, however, constitute only a small proportion of the material. The method of the following outline treatment will be to deduct from the object under consideration those symmetrical elements which seem to be directly traceable to non-æsthetic influences; such elements as are not thus to be accounted for must be taken as evidence of a direct pleasure in, and desire for symmetry on the part of primitive man. These possible non-æsthetic influences may be provisionally suggested to be the technical conditions of construction, the greater convenience and hence desirability of symmetrical objects for practical use, and the symmetrical character of natural forms which were imitated. The first great group of objects is given in primitive architecture. Here is found almost complete unanimity of design, the conical, hemispherical or beehive form being well-nigh universal. The hut of the Hottentots, a cattle-herding, half-nomadic people, is a good type of this. A circle of flexible staves is stuck into the ground, bent together and fastened at the top, and covered with skins. But this is the form of shelter constructed with the greatest ease, suitable to the demands of elastic materials, boughs, twigs, reeds, etc., and giving the greatest amount of space with the least material. There are, indeed, a few examples of the rectangular form of dwelling among various primitive races, but these seem to be more or less open to explanation by the theory advanced by Mr. V. Mendeleff, of the U.S. Bureau of Ethnology. "In his opinion the rectangular form of architecture which succeeds the type under discussion, must have resulted from the circular form by the bringing together within a limited area of many houses.... This partition would naturally be built straight as a two-fold measure of economy."[2] This opinion is confirmed by Mr. Cushing's observations among the Zuñi villages, where the pueblos have circular forms on the outskirts. Thus the shape of the typical primitive dwelling is seen to be fully accounted for as the product of practical considerations alone. It may therefore be dismissed as offering no especial points of interest for this inquiry. [2] Cushing, F.H.: 'Pueblo Pottery and Zuñi Culture-growth,' Rep. of Bur. of Ethnol., 1882-3, p. 473. Next in the order of primitive development are the arts of binding and weaving. The stone axe or arrow-head, for example, was bound to a wooden staff, and had to be lashed with perfect evenness,[3] and when in time the material and method of fastening changed, the geometrical forms of this careful binding continued to be engraved at the juncture of blade and handle of various implements. It should be noted, however, that these binding-patterns, in spite of their superfluous character, remained symmetrical. [3] Haddon, A.C.: 'Evolution in Art,' London, 1895, pp. 84 ff. On the great topic of symmetry in weaving, monographs could be written. Here it is sufficient to recall[4] that the absolutely necessary technique of weaving in all its various forms of interlacing, plaiting, netting, embroidering, etc., implies order, uniformity, and symmetry. The chance introduction of a thread or withe of a different color, brings out at once an ordered pattern in the result; the crowding together or pressing apart of elements, a different alternation of the woof, a change in the order of intersection, all introduce changes by the natural necessities of construction which have the effect of purpose. So far, then, as the simple weaving is concerned, the æsthetic demand for symmetry may be discounted. While it may be operative, the forms can be explained by the necessities of construction, and we have no right to assume an æsthetic motive. [4] Holmes, W.H.: 'Textile Art in its Relation to the Development of Form and Ornament,' Rep. of Bur. of Ethnol., 1884-5, p. 195. The treatment of human and animal forms in weaving is, however, indicative of a direct pleasure in symmetry. The human form appears almost exclusively (much schematized) _en face_. When in profile, as for instance in Mexican and South American work, it is doubled--that is, two figures are seen face to face. Animal figures, on the other hand, are much used as row-ornaments in profile.[5] It would seem that only the linear conception of the row or band with its suggestions of movement in one direction, justified the use of profile (_e.g._, in Peruvian woven stuffs), since it is almost always seen under those conditions, indicating that a limited rectangular space is felt as satisfactorily filled only by a symmetrical figure.[6] Moreover, and still more confirmatory of this theory, even these row-pattern profiles are immensely distorted toward symmetry, and every 'degradation' of form, to use Professor Haddon's term, is in the direction of symmetry. (See Fig. 1.) [5] Reiss, W., und Stubel, A.: 'Todtenfeld von Ancon,' Berlin, 1880-7, Bd. II. [6] Hein, W.: 'Die Verwendung der Menschen-Gestalt in Flechtwerken,' Mitteil. d. Anthrop. Gesellsch. in Wien, Bd. XXI. [Illustration: Fig. 1.] The shape of primitive pottery is conditioned by the following influences: The shapes of utensils preceding clay, such as skins, gourds, shells, etc., which have been imitated, the forms of basket models, and the conditions of construction (formation by the hands). For all these reasons, most of these shapes are circular. The only (in the strict sense) symmetrical shapes found are of unmistakably animal origin, and it is interesting to notice the gradual return of these to the eurhythmic form; puma, bird, frog, etc., gradually changing into head, tail and leg excrescences, and then handles and nodes (rectangular panels), upon a round bowl or jar L, as shown in the figures. In fact, in ancient American pottery,[7] at least, all the symmetrical ornamentations can be traced to the opposition of head and tail, and the sides between them, of these animal forms. But beyond this there is no degradation of the broad outline of the design. The head and tail, and sides, become respectively handles and nodes--but the symmetry becomes only more and more emphasized. And as in the case of textiles, the ornaments of the rectangular spaces given by the nodes are strikingly symmetrical. Many of these are from animal motives, and nearly always heads are turned back over the body, tails exaggerated, or either or both doubled, to get a symmetrical effect. Although much of the symmetrical ornament, again, is manifestly from textile models, its symmetrical character is so carefully preserved against the suggestions of the circular form that a direct pleasure in its symmetry may be inferred. (See Figs. 2-7.) [7] Cushing, F.H.: _op. cit._; Holmes, W.H.: three articles on pottery, Rep. of Bur. of Ethnol., 1882-83, p. 265, p. 367, and p. 443. [Illustration: Fig. 2] [Illustration: Fig. 3] [Illustration: Fig. 4] The subject of drawing can be here only touched upon, but the results of study go to show, in general, two main directions of primitive expression: pictorial representation, aiming at truth of life, and symbolic ornament. The drawings of Australians, Hottentots and Bushmen, and the carvings of the Esquimaux and of the prehistoric men of the reindeer period show remarkable vigor and naturalness; while the ornamentation of such tribes as the South Sea Islanders has a richness and formal beauty that compare favorably with the decoration of civilized contemporaries. But these two types of art do not always keep pace with each other. The petroglyphs of the North American Indians[8] exhibit the greatest irregularity, while their tattooing is extremely regular and symmetrical. The Brazilian savage [9] draws freehand in a very lively and grotesque manner, but his patterns are regular and carefully developed. Again, not all have artistic talents in the same direction. Dr. Schurtz, in his 'Ornamentik der Aino,'[10] says: "There are people who show a decided impulse for the direct imitation of nature, and especially for the representation of events of daily life, as dancing, hunting, fishing, etc. It is, however, remarkable that a real system of ornamentation is scarcely ever developed from pictorial representations of this kind; that, in fact, the people who carry out these copies of everyday scenes with especial preference, are in general less given to covering their utensils with a rich ornamentive decoration."[11] Drawing and ornament, as the products of different tendencies, may therefore be considered separately. [8] Mallery, Garrick: 'Pictographs of the North American Indians,' Rep. of Bur. of Ethnol., 1882-3, p. 13. [9] Von den Steinen, Karl: 'Unter den Naturvôlkern Zentral-Brasiliens,' Berlin, 1894. [10] _Internal. Archiv s. Ethnog._, Bd. IX. [11] Cf. Andrée, Richard: 'Ethnographische Parallelen,' Neue Folge, Leipzig, 1889, S. 59. The reason for the divergence of drawing and ornament is doubtless the original motive of ornamentation, which is found in the clan or totem ideas. Either to invoke protection or to mark ownership, the totem symbol appears on all instruments and utensils; it has been shown, indeed, that practically all primitive ornament is based on totemic motives.[12] Now, since a very slight suggestion of the totem given by its recognized symbol is sufficient for the initiated, the extreme of conventionalization and degradation of patterns is allowable, and is observed to take place. The important point to be noted in this connection is, however, that all these changes are toward symmetry. The most striking examples might be indefinitely multiplied, and are to be found in the appended references (see Figs. 8 and 9). [12] Haddon, _op. cit._; Frazer, J.G.: 'Totemism,' 1887; Grosse, Ernst: Anfänge der Kunst,' Freiburg i. B. u. Leipzig, 1894. [Illustration: Fig. 5.] [Illustration: Fig. 6.] [Illustration: Fig. 7.] We may distinguish here, also, between the gradual disintegration and degradation of pattern toward symmetry, as seen in the examples just given, and the deliberate distortion of figures for a special purpose. This is strikingly shown in the decorative art of the Indians of the North Pacific coast. They systematically represent their totem animals--their only decorative motives--as split in symmetrical sections, and opened out flat on the surface which is to be covered[13] (see Fig. 11). Dr. Boas argues that their purpose is to get in all the received symbols, or to show the whole animal, but, however this may be, every variation introduces symmetry even where it is difficult to do so, as in the case, for instance, of bracelets, hat-brims, etc. (Fig. 10). This may in some cases be due to the symmetrical suggestions of the human body in tattooing,[14] but it must be so in comparatively few. [13] Boas, Franz: 'Decorative Art of the Indians of the North Pacific Coast,' _Bulletin_ of Am. Mus. of Nat. Hist., Vol. IX. [14] Mallery, G.: _op. cit._; Haddon, A.C.: _op. cit._, p. 257; 'Decorative Art of British New Guinea,' Cunningham Memoir X., Royal Irish Acad., 1894, p. 26. [Illustration: Fig. 8.] [Illustration: Fig. 9.] [Illustration: Fig. 10] The primitive picture has for its object not only to impart information, but to excite the very definite pleasure of recognition of a known object. All explorers agree in their accounts of the savage's delight in his own naïve efforts at picture making. All such drawings show in varying degrees the same characteristics; first of all, an entire lack of symmetry. In a really great number of examples, including drawings and picture-writing from all over the world, I have not found one which showed an attempt at symmetrical arrangement. Secondly, great life and movement, particularly in the drawings of animals. Thirdly, an emphasis of the typical characteristics, the logical marks, amounting sometimes to caricature. The primitive man draws to tell a story, as children do. He gives with real power what interests him, and puts in what he knows ought to be there, even if it is not seen, but he is so engrossed by his interest in the imitated object as to neglect entirely its relation to a background. [Illustration: FIG. 11] Now, this very antithesis of ornament and picture is enlightening as to the dawn of æsthetic feeling, and the strongest confirmation of our hypothesis of an original impulse to symmetry in art. In the ornamentation of objects the content or meaning of the design is already supplied by the merest hint of the symbol which is the practical motive of all ornamentation. The savage artist need, therefore, concern himself no more about it, and the form of his design is free to take whatever shape is demanded either by the conditions of technique and the surface to be ornamented, or by the natural æsthetic impulse. We have found that technical conditions account for only a small part of the observed symmetry in pattern, and the inference to a natural tendency to symmetry is clear. Pictorial representation, on the other hand, is enjoyed by the primitive man merely as an imitation, of which he can say, 'This is that animal'--to paraphrase Aristotle's Poetics. He is thus constrained to reproduce the form as it shows meaning, and to ignore it as form, or as his natural motor impulses would make it. To sum up the conclusions reached by this short survey of the field of primitive art, it is clear that much of the symmetry appearing in primitive art is due (1) to the conditions of construction, as in the form of dwellings, binding-patterns, weaving and textile patterns generally; (2) to convenience in use, as in the shapes of spears, arrows, knives, two-handled baskets and jars; (3) to the imitation of animal forms, as in the shapes of pottery, etc. On the other hand (1) a very great deal of symmetrical ornament maintains itself _against_ the suggestions of the shape to which it is applied, as the ornaments of baskets, pottery, and all rounded objects; and (2) all distortion, disintegration, degradation of pattern-motives, often so marked as all but to destroy their meaning, is in the direction of geometrical symmetry. In short it is impossible to account for more than a small part of the marked symmetry of primitive art by non-æsthetic influences, and we are therefore forced to conclude an original tendency to create symmetry, and to take pleasure in it. A strong negative confirmation of this is given, as noted above, by the utter lack of symmetry of the only branch of art in which the primitive man is fully preoccupied with meaning to the neglect of shape; and by the contrast of this with those branches of art in which attention to meaning is at its minimum. The question put at the beginning of this section must thus be answered affirmatively. There is evidence of an original æsthetic pleasure in symmetry. III. EXPERIMENTS IN SUBSTITUTIONAL SYMMETRY. _A. Method of Experiment._ A certain degree of original æsthetic pleasure in symmetry may be considered to have been established by the preceding section, and, without considering further the problems of real or geometrical symmetry, it may now be asked whether the pleasure aroused by the form of asymmetrical objects is not at bottom also pleasure in symmetry; whether, in other words, a kind of substitution of factors does not obtain in such objects, which brings about a psychological state similar to that produced by real symmetry. The question what these substituted factors may be can perhaps be approached by a glance at a few pictures which are accepted as beautiful in form, although not geometrically symmetrical. Let us take, for instance, several simple pictures from among the well-known altar-pieces, all representing the same subject, the _Madonna Enthroned_ with _Infant Christ_, and all of generally symmetrical outline. It seems, then, reasonable to assume that if the variations from symmetry show constantly recurring tendencies, they represent the chief factors in such a substitutional symmetry or balance, supposing it to exist. The following pictures are thus treated in detail, M. denoting Madonna; C., Child; and Cn., Central Line. The numbers refer to the collection of reproductions used exclusively in this investigation, and further described in section IV. 1. 56, Martin Schöngauer: _Madonna in Rose-arbor._ M. is seated exactly in Cn., C. on Right, turning to Right. M. turns to Left, and her long hair and draperies form one long unbroken line down to Left lower corner. All other details symmetrical. 2. 867, Titian: _Madonna_. The picture is wider than it is high. M. stands slightly to Right of Cn.; C. on Right. Both turn slightly to Left, and the drapery of M. makes a long sweep to Left. Also a deep perspective occupies the whole Left field. 3. 248, Raphael: _Madonna_ (The Bridgewater Madonna). M. sits in Cn., turning to Left; C. lies across her lap, head to Left, but his face turned up to Right, and all the lines of his body tending sharply down to Right. In 1, all the elements of the picture are symmetrical except the position of C. on the Right, and the long flowing line to Left. In 2, there is a slightly greater variation. The mass of the figures is to Right, and the C. entirely over against the deep perspective and the flowing line on the Left, and the direction of both faces toward that side. In 3, the greater part of C.'s figure on Left is opposed by the direction of his lines and movement to Right. Thus these three pictures, whether or not they are considered as presenting a balance, at least show several well-defined factors which detach themselves from the general symmetrical scheme. (1) Interest in C. is opposed by outward-pointing line; (2) greater mass, by outward-pointing line, deep vista, and direction of attention; and (3) again interest by direction of line and suggestion of movement. This analysis of several æsthetically pleasing but asymmetrical arrangements of space strongly suggests that the elements of large size, deep perspective, suggested movement, and intrinsic interest are in some way equivalent in their power to arouse those motor impulses which we believe to constitute the basis of æsthetic response. It is the purpose of these experiments to follow up the lines of these suggestions, reducing them to their simplest forms and studying them under exact conditions. But before describing the instruments and methods of this experimental treatment, I wish to speak of the articles on the 'Æsthetics of Simple Form,' published as Studies from the Harvard Psychological Laboratory, by Dr. Edgar Pierce.[15] These articles, sub-entitled 'Symmetry' and 'The Functions of the Elements' seem at first sight to anticipate the discussions of this paper; but a short analysis shows that while they point in the same direction, they nevertheless deal with quite different questions and in a different manner. In the statement of his problem, indeed, Dr. Pierce is apparently treading the same path. [15] Pierce E.: PSYCH. REV., 1894, I., p. 483; 1896, III., p. 270. He says: "Can a feeling of symmetry, that is, of æsthetical equality of the two halves, remain where the two sides are not geometrically identical; and if so, what are the conditions under which this can result--what variations of one side seem æsthetically equal to the variations of the other side?" Some preliminary experiments resulted in the conclusion that an unsymmetrical and yet pleasing arrangement of a varied content rests on the pleasure in unity, thus shutting out the Golden Section choice, which depends on the pleasure in variety. That is, the choices made will not in general follow the golden section, but 'when the figure consists of two halves, the pleasure must be a feeling of æsthetical symmetry.' The final experiments were arrangements of lines and simple figures on a square, black background in which the center was marked by a white vertical line with a blue or a red line on each side. On one side of these central lines a line was fixed; and the subject had to place on the other side lines and simple figures of different sizes and different colors, so as to balance the fixed line. The results showed that lines of greater length, or figures of greater area must be put nearer the center than shorter or smaller ones--'A short line must be farther than a long one, a narrow farther than a wide, a line farther than a square; an empty interval must be larger than one filled, and so on.' And for colors, "blue, maroon and green, the dark colors, are the farthest out; white, red and orange, the bright colors, are nearest the center. This means that a dark color must be farther out than a bright one to compensate for a form on the other side. The brightness of an object is then a constant substitute for its distance in satisfying our feeling of symmetry." Now from these conclusions two things are clear. By his extremely emphasized central line, and his explicit question to the subjects, 'Does this balance?' the author has excluded any other point of view than that of mechanical balance. His central fulcrum is quite overpowering. Secondly, his inquiry has dealt only with size and color, leaving the questions of interest, movement, and perspective untouched. But just the purpose of this experimental study is to seek for the different and possibly conflicting tendencies in composition, and to approximate to the conditions given in pictorial art. It is evident, I think, that the two studies on symmetry will not trespass on each other's territory. The second paper of Dr. Pierce, on 'The Functions of the Elements,' deals entirely with the relation of horizontal and vertical positions of the æsthetic object and of the subject to æsthetic judgments, and has therefore no bearing on this paper. For his apparatus Dr. Pierce used a surface of black cloth stretched over black rubber, 1 m. square. Now an investigation which is to deal with complicated and varied relations, resembling those of pictures, demands an instrument resembling them also in the shape of the background. A rectangle 600 mm. broad by 400 mm. high seemed to meet this requirement better than the square of Dr. Pierce. Other parts, also, of his instrument seemed unfitted for our purpose. The tin, 5 cm. broad and confined to the slits across the center of the square, gave not enough opportunity for movement in a vertical direction, while the scale at the back was very inconvenient for reading. To supply these lacks, a scale graduated in millimeters was attached on the lower edge of the board, between a double track in which ran slides, the positions of which could be read on the scale. To the slides were attached long strips of tin covered with black cloth. On these strips figures glued to small clamps or clasps could be slipped up or down; this arrangement of coördinates made it possible to place a figure in any spot of the whole surface without bringing the hands into the field of view. The experiments were made in a dark room, in which the apparatus was lighted by an electric globe veiled by white paper and hung above and behind the head of the subject, so as not to be seen by him and to cast no shadow: in this soft light of course the black movable strips disappeared against the black background. A gray paper frame an inch and a half wide was fitted to the black rectangle to throw it up against the black depths of the dark room--thus giving in all details the background of a picture to be composed. The differences in method between the two sets of experiments were fundamental. In Dr. Pierce's experiments the figures were pulled from one side to the other of the half-square in question, and the subject was asked to stop them where he liked; in those of the writer the subject himself moved the slides back and forth until a position was found æsthetically satisfactory. The subject was never asked, Does this balance? He was indeed requested to abstract from the idea of balance, but to choose that position which was the most immediately pleasing for its own sake, and so far as possible detached from associations. I have said that Dr. Pierce intentionally accentuated the center. The conditions of pictorial composition suggest in general the center only by the rectangular frame. Most of my experiments were, therefore, made without any middle line; some were repeated with a middle line of fine white silk thread, for the purpose of ascertaining the effect of the enhanced suggestion of the middle line. But the chief difference came in the different treatment of results. Dr. Pierce took averages, whereas the present writer has interpreted individual results. Now, suppose that one tendency led the subject to place the slide at 50 and another to place it at 130 mm. from the center. The average of a large number of such choices would be 90--a position very probably disagreeable in every way. For such an investigation it was evident that interpretation of individual results was the only method possible, except where it could be conclusively shown that the subjects took one and only one point of view. They were always encouraged to make a second choice if they wished to do so, as it often happened that one would say: 'I like both of these ways very much.' Of course, individual testimony would be of the highest importance, and a general grouping into classes and indication of the majority tendency would be the only way to treat the results statistically. And indeed in carrying out the experiments this caution was found absolutely necessary. In all but one or two of the sections, the taking of averages would have made the numerical results absolutely unintelligible. Only the careful study of the individual case, comparison of various experiments on the same person to find personal tendencies, and comparison of the different tendencies, could give valuable results for the theory of symmetry. The first question to be taken up was the influence of right and left positions on choice. A long series of experiments was undertaken with a line 80×10 mm. on one side and a line 160×10 mm. on the other, in which the positions of these were reversed, and each in turn taken as fixed and variable, with a view to determining the effect of right and left positions. No definite conclusions emerged; and in the following experiments, most of which have been made for both right and left positions, the results will be treated as if made for one side alone, and, where averages are taken, will be considered as indifferently left or right. The experiments of Dr. Pierce were made for only one position of the fixed line--at 12 cm. distance from the center. The characteristic of the following experiments is their reference to all positions of the fixed line. For instance a fixed line, 10 cm. in length at 12 cm. distance from the center, might be balanced by a line 5 cm. in length at 20 cm. distance. But would the distance be in the same proportion for a given distance of the fixed line of say 20 or 25 cm.? It is clear that only a progressive series of positions of the fixed line would suggest the changes in points of view or tendencies of choice of the subject. Accordingly, for all the experiments the fixed line or other object was placed successively at distances of 20, 40, 60 mm., etc., from the center; or at 40, 80 mm., etc., according to the character of the object, and for each of these fixed points the subject made one or two choices. Only an understanding of the direction in which the variable series moved gave in many cases an explanation for the choice. Each choice, it should be added, was itself the outcome of a long series of trials to find the most pleasing position. Thus, each subject made only about ten choices in an hour, each of which, as it appears in the tables, represents a large number of approximations. _B. Experiments on Size._ I have said that different tendencies or types of choice in arrangement appeared. It will be convenient in the course of explaining in detail the method of experiment, to discuss at the same time the meaning of these types of choice. From analysis of the pictures, the simplest suggestion of balance appeared in the setting off against each other of objects of different sizes;--an apparent equivalence of a large object near the center with a small object far from the center; thus inevitably suggesting the relations of the mechanical balance, or lever, in which the heavy short arm balances the light long arm. This was also the result of Dr. Pierce's experiments for one position of his fixed line. The experiments which follow, however, differ in some significant points from this result. The instrument used was the one described in the preceding section. On one side, in the middle of the vertical strip, was placed the 'fixed' line, denoted by F., and the subject moved the 'variable' line, denoted by V., until he found the arrangement æsthetically pleasing. The experimenter alone placed F. at the given reading, and read off the position of V. After the choice F. was placed at the next interval, V. was again tried in different positions, and so on. In the following tables the successive positions of F. are given in the left column, reading downward, and the corresponding positions of V. in the right column. The different choices are placed together, but in case of any preference the second choice is indicated. The measurements are always in millimeters. Thus, F. 40, V. 60, means that F. is 40 mm. to one side of the center, and V. 60 mm. to the opposite side. F. 80×10, V. 160×10, means that the white cardboard strips 80 mm.×10 mm., etc., are used. The minus sign prefixed to a reading means that the variable was placed on the side of the fixed line. An X indicates æsthetic dislike--refusal to choose. An asterisk (*) indicates a second choice. The following tables are specimen sets made by the subjects _C, O_, and _D_. I. (a) F. 80×10, V. 160×10. F. V. C. O. D. 40 62, 120 166, 130 28, 24 80 70, 110 104, 102 80, 126 120 46, X 70, 46 68,--44, 128* 160 26, 96 50, 25 85, 196,--88* 200 20, X 55, X --46, 230,* 220,--110* I. (b) F. 160×10, V. 80×10. F. V. C. O. D. 40 74, 64 60, 96 27, 34 80 76, 65 72, 87 55, 138 120 60, 56 48, 82 70, 174 160 29, 74 16, 77 --114, 140, 138, 200 200 96, 36 25, 36 177,--146,--148, 230 Now, on Dr. Pierce's theory, the variable in the first set should be nearer the center, since it is twice the size of the fixed line;--but the choices V. 120, 166, 130 for F. 40; V. 110, 104, 102, 126 for F. 80; V. 128 for F. 120; V. 196 for F. 160; V. 230, 220 for F. 200, show that other forces are at work. If these variations from the expected were slight, or if the presence of second choices did not show a certain opposition or contrast between the two positions, they might disappear in an average. But the position of F. 40, over against V. 120, 166, 130, is evidently not a chance variation. Still more striking are the variations for I. (_b_). Here we should expect the variable, being smaller, to be farther from the center. But for F. 40, we have V. 27, 34; for F. 80, all nearer but two; for F. 120, V. 60, 56, 48, 82, 70; for F. 160, V. 29, 74, 16, 77, 138, and for F. 200, V. 96, 36, 25, 36, 177--while several positions on the same side of the center as the constant show a point of view quite irreconcilable with mechanical balance. II. (a) F. 2 LINES 80×10. V. SINGLE LINK 80×10. F. V. C. O. P. 40- 60 58, 114* 138, 20 96, 84 166 60- 80 48 40, 138* 100, 56 150 80-100 64 70, 162* 47, 87 128 100-120 70 to 80 60 53, 53 X 120-140 58 82 50, 48 35 140-160 74 95 to 100 22, 32 37 160-180 72 102 X, X 42 180-200 90 X X, X 50 Here the variable should supposedly be the farther out; but we have V. 58, 20 for F. 40-60; V. 48, 40, 56 for F. 60; V. 64, 70, 87 for F. 80; no larger choice for F. 100-120; indeed, from this point on everything nearer, and very much nearer. We can trace in these cases, more clearly perhaps than in the preceding, the presence of definite tendencies. _O_ and _P_, from positions in accord with the mechanical theory, approach the center rapidly; while _C_ is seldom 'mechanical,' but very slowly recedes from the center. The large number of refusals to choose assures us that the subjects demand a definitely pleasant arrangement--in other words, that every choice is the expression of a deliberate judgment. Taking again the experiments 1. (a) and 1. (b), and grouping the results for nine subjects, _C_, _O_, _A_, _S_, _H_, _G_, _D_, and _P_, we obtain the following general types of choice. The experiments were repeated by each subject, so that we have eighteen records for each position. I should note here that preliminary experiments showed that near the frame the threshold of difference of position was 10 mm., or more, while near the center it was 4 or 5 mm.; that is, arrangements were often judged symmetrically equal which really differed by from 4 to 10 mm., according as they were near to or far from the center. In grouping types of choice, therefore, choices lying within these limits will be taken as belonging to the same type. EXP. 1. (a) F.(80 X 10). V.(160 X 10). 1. F. 40. V. 40.¹ Types of Choice for V. (1) 24 24 25 28 (2) 40 42 45 45 40 40 40 (3) 62 65 (4) 100 105 1O9 120 130 136 120 (5) 166 180 200 200 200 200 160 160 ¹This table is obtained by taking from the full list, not given here, of 1. (b) F. (l60 X 10), V. (80 X 10), those positions of 160 X 10 where the variable 80 X 10 has been placed at or near 40, thus giving the same arrangement as for 1. (a). It might be objected that a group 40-65 (2-3) would not be larger than one of 100-136 (4), but the break between 45 and 62 shows the zones not continuous. Moreover, as said above, the positions far from the center have a very large difference threshold. I. (a) 2. F. 80:--(1) 24, (2) 50, (3) 68 70, (4) 80 85 94 95 85, (5) 102 104 110 120 124 126 125* 132, (6) 187; also V. 80:--(2) 40 40, (4) 80, (5) 120 120, (6) 160 160. I. (a) 3. F. 120:--(1) 44 46, (2) 64 48 70 70, (3) 85 95 97 91, (4) 113 113 118, (5) 168 169 178;--44, X; also V. 120:--(1) 40 40, (3) 80 80 80, (4) 120 120, (5) 160 160. I. (a) 4. F. 160:--(1) 25 26, (2) 40 50 57, (3) 82 85 95 100*, (4) 114 115 130, (5) 145 145 156 162, (6) 196, (7)--88*--150*--105. I. (a) 5. F. 200:--(1) 20 23 28 36, (2) 55, (3) 108 124 130*, (4) 171 189 199 195, (5) 220 230*, (6)--46--90--110*. On comparing the different groups, we find that in 1 and 2 there is a decided preference for a position somewhat less than half way between center and frame--more sharply marked for 1 than for 2. From 3 onward there is a decided preference for the mechanical arrangement, which would bring the larger strip nearer. Besides this, however, there are groups of variations, some very near the center, others approaching to symmetry. The maintenance of geometrical symmetry at a pretty constant ratio is to be noted; as also the presence of positions on the same side of the center as the fixed line. Before discussing the significance of these groups we may consider the results of Experiment II. (F. double line 80×10, V. single line 80×10) without giving complete lists. We notice therein, first of all, the practical disappearance of the symmetrical choice; for F. 40-60, 60-80, 80-100, a tendency, decreasing, however, with distance from the center, to the mechanical arrangement; for F. 100-120, and all the rest, not one mechanical choice, and the positions confined almost entirely to the region 35-75. In some cases, however, the mechanical choice for (1) 40-80, (2) 60-80, was one of two, _e.g._, we have for (1) 20 and 138, for (3) 70 and 162; in the last two cases the mechanical being the second choice. Now the reversals of the mechanical choice occur for Exp. I. in 1 and 2 (F. 40 and F. 80); that is, when the small fixed line is near the center, the larger variable is distant. For Exp. II. the reversals, which are much more marked, occur in all cases _beyond_ F. 40, F. 60 and F. 80; that is, when the double constant line is far from the center, the single variable approaches. If the mechanical theory prevailed, we should have in Exp. I. the lines together in the center, and in Exp. II. both near the fringe. From the individual testimony, based both on I. (_a_) and I. (_b_), it appears that subject _M_ is perfectly uniform in mechanical choice when the fixed line is the small line--_i.e._ when it moves out, the larger is placed near the center; but when the conditions of mechanical choice would demand that, as the larger fixed line moves out, the small variable one should move out farther, he regularly chooses the reverse. Nevertheless, he insists that in just these cases he has a feeling of equilibrium. _A_ also takes the mechanical choice as the small fixed line goes farther from the center; but when the fixed line is large and leaves the center, he reverses the mechanical choice--evidently because it would take the small line too far out. As he says, 'he is always disturbed by too large a black space in the center.' _G_ almost always takes the mechanical choice;--in one whole set of experiments, in which the fixed line is the large line, he reverses regularly. _H_ takes for F. (80×10) the mechanical choice only for the positions F. 160 and F. 200--_i.e._, only when F. is very far from the center and he wishes V. (160×10) nearer. For F. (160×10) he makes six such choices out of ten, but for positions F. 160 and F. 200 he has V. 44, 65 and 20. _S_ takes for F. (160×10) at F. 120, V. 185 and-70; says of V. 185, which is also his choice for F. (160×10) at F. 80, 'I cannot go out further, because it is so hard to take in the whole field.' For F. (160×10) at F. 200, he has V. 130 and 60; says of V. 60, 'Very agreeable elements in connection with the relation of the two lines.' _C_ takes for F. (80×10) only one mechanical choice until it is at F. 120. Then always mechanical, _i.e._, nearer center; for F. (160×10) makes after the position F. 40 no mechanical choice, _i.e._, V. is nearer center. It is evident from the above tables and individual cases that the reversals from the mechanical choice occur only when the mechanical choice would bring both lines in the center, or both near the edges, and the subjective testimony shows from what point of view this appears desirable. The subjects wish 'to take in the whole field,' they wish 'not to be disturbed by too large a black space in the center'; and when, in order to cover in some way the whole space, the small line is drawn in or the large one pushed out, they have, nevertheless, a feeling of equilibrium in spite of the reversal of mechanical balance. Accepting for the present, without seeking a further psychological explanation, the type of 'mechanical balance,' in which amount of space is a substitute for weight, as the one most often observed, we have to seek some point of view from which this entire reversal is intelligible. For even the feeling that 'the whole field must be covered' would hardly account for an exact interchanging of positions. If size gives 'weight,' why does it not always do so? A simple answer would seem to be given by the consideration that we tend to give most attention to the center of a circumscribed space, and that any object in that center will get proportionately more attention than on the outskirts. The small line near the center, therefore, would attract attention by virtue of its centrality, and thus balance the large line, intrinsically more noticeable but farther away. Moreover, all the other moments of æsthetic pleasure, derived from the even filling of the space, would work in favor of this arrangement and against the mechanical arrangement, which would leave a large black space in the middle. The hypothesis, then, that the demand for the filling of the whole space without large gaps anywhere enters into competition with the tendency to mechanical balance, and that this tendency is, nevertheless, reconciled with that demand through the power of a central position to confer importance, would seem to fit the facts. It is, of course, clear that neither 'mechanical balance' nor the balance of 'central' with 'intrinsic' importance have been yet accounted for on psychological grounds; it is sufficient at this point to have established the fact of some kind of balance between elements of different qualities, and to have demonstrated that this balance is at least not always to be translated into the 'mechanical' metaphor. _C. Experiments on Movement._ In the preceding experiments the element of size was isolated, and it was sought to discover, in pleasing combinations of objects of different sizes, the presence of some kind of balance and the meaning of different tendencies of arrangement. The relative value of the two objects was taken as determined on the assumption, supported by common sense, that under like conditions a large object is given more attention than a small one. If the unequal objects seem to balance each other, then the only other condition in which they differ, their distance from the center, must be the cause of their balancing. Thus the influence of relative position, being the only unknown quantity in this balance-equation, is easily made out. The following experiments will deal with the as yet quite undetermined elements of suggested movement, perspective and intrinsic interest. By combining objects expressing them, each with another simple object of the same size, another equation will be obtained in which there is only one unknown quantity, the sizes of the objects being equal and the influence of relative position being at least clearly indicated. 1. Movement. The experiments on suggestion of movement were made by _C_, _O_ and _P_. Suggestions of movement in pictures are of two kinds--given by lines pointing in a direction which the eye of the spectator tends to follow, and by movement represented as about to take place and therefore interpreted as the product of internal energy. Thus, the tapering of a pyramid would give the first kind of suggestion, the picture of a runner the second kind. Translated into terms of experiment, this distinction would give two classes dealing with (A) the direction of a straight line as a whole, and (B) the expression of internal energy by a curve or part of a line. In order to be able to change the direction of a straight line at a given point, a strip of tin two inches long was fastened by a pivot to the usual clasp which slipped up and down on the vertical black strip. The tin strip could be moved about the pivot by black threads fastened to its perforated ends. A strip of cardboard glued upon it would then take its direction. The first experiments, made with the usual 80×10 strip, proved very disagreeable. The subject was much disturbed by the blunt ends of the strip. The variable (pivoted) line was then slightly pointed at the upper end, and in the final experiments, in which both are oblique, both strips were pointed at each end. In Exp. III. a line pointing at an angle from the perpendicular was set over against a line of the same dimensions in the ordinary position. Exp. III. (_a_) F. (80×10) pointed up toward center at 145°, V. (80×10). F. 40:--(1) 39 48 48, (2) 60 66 68, (3) 97 97, (4) 156* 168*. F. 60:--(1) 45, (2) 60 62 65 68 90, (3) 90 94, (4) 117 128 152 155. F. 80:--(1) 50 44*, (2) 74 76 77, (3) 94 100 106 113 115 116, (4) 123 124* 140 165* 169*. F. 100:--(1) 36 58 60 65* 65 74 77 80 87, (2) 98 108 118, (3) 114* 168 186* 170 136*. F. 120:--(1) 40 46 54 60 63 76 96 97 111, (2) 115 120 126* 137*, (3) 170 170*. F. 140:--(1) 45 52 65 65 76 76 86 90, (2) 109 111, (3) 125 140*, (4) 168*. F. 160:--(1) 38 50 50 60, (2) 80 90 96 98 98, (3) 176*. F. 180:--(1) 21 23, (2) 54 70 84 90, (3) 100 100 108 114 120, (4) 130 145*. F. 200:--(1) -2, (2) 33 37 50, (3) 106 110 to 120 115 120 130 132 138 142. The most striking point about these groups is the frequency of positions far from the center when F. also is far out. At F. 120, a position at which the mechanical choice usually prevails if F. is smaller, a very marked preference indeed appears for positions of V. nearer the center--in fact, there is only one opposing (first) choice. Now, if it is not the wide space otherwise left which pulls the variable in,--and we see from a note that the subjects have no feeling of a large empty space in the center,--it must be that F. has the same effect as if it were really smaller than V., that is, mechanically 'light.' We see, in fact, that the moment F. has passed the point, between 80 and 100, at which both lines close together in the center would be disagreeable, the preference is marked for inner positions of V., and I repeat that this cannot be for space-filling reasons, from the testimony of F. 200 (3). And this 'lightness' of the line pointed in at 45° is indeed what we should have expected _a priori_ since we found that objective heaviness is balanced by a movement out from the center on the mechanical principle. If movement out and objective heaviness are in general alike in effect, then movement in and objective lightness should be alike in effect, as we have found to be the case from the preceding experiments. The inward-pointed line does not actually move in, it is true, but it strongly suggests the completion of the movement. It enters into the 'mechanical' equation--it appears to balance--as if it had moved. The point, however, in which this 'lightness' of the inward-pointed line differs from that of the small or short line is its space-filling quality. It suggests movement in a certain direction, and, while giving the mechanical effect of that movement as completed, seems also in a sense to cover that space. We see from F. 180 (3), (4), and 200 (3), that the subject does not shrink from large spaces between the lines, and does not, as in Exp. I. (_a_), 4 and 5, bring the variable, which in both cases is evidently 'heavier,' to the center. This must be from the fact that the empty space does not in this experiment feel empty--it is filled with energy of the suggested movement. This view is confirmed by the dislike which the subjects show to the position F. 40; F., being 'lighter,' but the object of attention as close to the center, might well balance V. far out. But as if the whole variable field would be in that case 'overfilled,' the records show 50 per cent. of refusals to choose for this position. In brief, then, a straight line suggesting movements in a certain direction has the effect, in the general scheme of mechanical balance, of a static position in which this movement has been carried out, with the added suggestion of the filling of the space over which such movement is suggested. A few additional experiments were made with a point on the upper end of V. The groups of III. (_a_) are maintained almost exactly: F. 120 is again strikingly 'mechanical'; after F. 120 there are only two mechanical choices out of nineteen; while for F. 40, as in Exp. III. (_a_), out of six choices, four are either refusals or question-marked. Exp. IV. Both lines took oblique directions, and, to get a pleasing effect, were pointed at both ends. They were of the usual size, 80×10 mm., but 1 mm. broader to allow for the effect of length given by the points. F. was fixed at 45°, as in III. (_a_), on the points 40, 80, 120 and 160; V. moved also on fixed points, 60, 100, 140, 180, for each position of F., but on each point was adjusted at a pleasing angle. Thus, there were four positions of V. to each of F., each with one or two angular positions; V. was always in the first quadrant. The numbers of the table give the angular degrees of V. F. 40, V. 60:--(1) 10 12 38 44, (2) 50 57* 60, (3) 70. V. 100:--(1) 15 15 30 30, (2) 50 55 50, (3) 69 70*. V. 140:--(1) 12* 14 18 18, (2) 60 60 49, (3) 72. V. 180:--(1) 12 10 38, (2) 60 50, (3) 75. [Many refusals at 140 and 180.] F. 80, V. 60:--(1) 11, (2) 25 35 36*, (3) 45 48 55 58 60, (4) 69. V. 100:--(1) 16 15, (2) 24 27 35 40, (3) 52, (4) 62 74*. V. 140:--(1) 10 15 16, (2) 22 28, (3) 40 40 59 59, (4) 70. V. 180:--(1) 14 8, (2) 28, (3) 41 46, (4) 68 79. F. 120, V. 60: (1) 28, (2) 42 44 35, (3) 52 58 62 65 65. V. 100:--(1) 9, (2) 23 25, (3) 38 40 40 42 58, (4) 68 70. V. 140:--(1) 10, (2) 20 26 21* 24 29, (3) 34 42 42 44 55*, (4) 75. V. 180:--(1) 17 26, (2) 40 42 46, (3) 62 64 70 70*. F. 160, V. 60:--(1) 20 39, (2) 18, (3) 58 60 64 68 70. V. 100:--(1) 23 25 30 38, (2) 44 44 49, (3) 55 58 65. V. 140:--(1) 5, (2) 31 35 40 40 32, (3) 54 55 68. V. 180:--(1) 50 50 58 60, (2) 75. The tendency to mechanical balance would, according to our previous analysis, lead the variable to take a direction which, in its suggestion of motion inward, should be more or less strong according as it were farther from or nearer to the center than the fixed line. Such motion inward would, of course, be more strongly suggested by an angle less than 45° than by an angle greater than 45°, and it seems that the angles chosen are in general in harmony with this expectation. For the positions where F. is nearer the center than V. there is a preponderance of the angles less than 45° (cf. F. 40 and F. 80, V. 100 and 140; F. 120, V. 140, 180). When V. passes over to a position farther from the center than F. (_e.g._, from F. 80, V. 60, to F. 80, V. 100 and from F. 120, V. 60, to F. 120, V. 140) the change is marked. In every case where F. is farther from the center than V. (_i.e._, F. 80, V. 60; F. 120, V. 60 and V. 100; F. 160, V. 60, V. 100 and V. 140), there are to be noticed a lack of the very small angles and a preponderance of the middle and larger angles. F. 160, V. 140 and 180 seem to be the only exceptions, which are easily explainable by a dislike of the extremely small angle near the edge; for it appears from the remarks of the subjects that there is always a subconsciousness of the direction suggested by the lower pointed end of the line. For the outer positions of both lines, a large angle would leave the center empty, and a small one would be disagreeable for the reason just given; and so we find, indeed, for F. 160, V. 100, 140, 160, the middle position the favorite one. The representation of action may be translated into experimental terms by expressing it as a line which changes its direction, thus seeming to be animated by some internal energy. The forms chosen were three curves 'bulging' from a straight line in differing degrees, and two straight lines with projections. _C_ and _O_ were the subjects. The results are given in outline. Exp. V. Curve I. See Fig. 12, I (1) Curve out (turned away from center). (_a_) F. (80×10), V. Curve. About half the positions of V. are farther from the center than F. _O_ at first refuses to choose, then up to F. 120 puts V. farther from the center than F. _C_ has a set of positions of V. nearer the center and several second choices farther than F. (_b_) F. Curve, V. (80×10). No position of V. nearer center than F. _O_ puts line farther out up to F. 160, then nearer than F. _C_ has a set of nearly symmetrical choices and another where V. is much farther out than F. (2) Curve in (turned toward center). (_a_) F. (80×10), V. Curve. _C_ is absolutely constant in putting V. farther from center than F. _O_, after F. 100, brings it slightly nearer. (_b_) F. Curve, V. (80×10). _C_, except for F. 40, invariably puts V. nearer center than F. _O_ moves between 90 and 135, putting V. farther to F. 100, nearly symmetrical at F. 100 and 120, and after F. 120, from 100 to 135. [Illustration: FIG. 12] Exp. V. Curve II. See Fig. 12, II. (1) Curve out. (_a_) F. (80×10), V. Curve. In every case but one V. is nearer center than F. (_b_) F. Curve, V. (80×10). _C_ puts V. farther from center than F. _O_ puts V. farther or symmetrical up to F. 120, then nearer than F. (2) Curve in. (_a_) F. 80×10, V. Curve. _C_ has V. always farther from center than F., but a second parallel set, omitting F. 40 (all second choices), of symmetrical positions. _O_ begins with V. farther from center, but from F. 120 has V. always nearer, though gradually receding from the center. (_b_) F. Curve. V. (80×10). _C_, refusing for F. 40, continues his parallel sets, one with V. always nearer than F., another with symmetrical positions. _O_ begins with V. nearer, changes at F. 120, and continues with V. farther. Recapitulating these results, grouping together the outward and inward positions of the curves, and indicating the distance of the line from the center by C.-L., and of the curve from the center by C.-Cv., we have: _Out_. Cv. I. (_a_) Indeterminate. (_b_) C.-Cv. < C.-L. (except where large gap would be left). Cv. II. (_a_) C.-Cv. < C.-L. (all cases but one). (_b_) C.-Cv. < C.-L. (except where large gap would be left). _In._ Cv. I. (_a_) C.-Cv. > C.-L. (except a few cases to avoid gap). (_b_) C.-Cv. > C.-L. (more than half of cases). Cv. II. (_a_) C.-Cv. > C.-L. (except a few cases to avoid gap). (_b_) C.-Cv. > C.-L. (except a few cases to avoid gap). It is evident that in the great majority of cases when the curve turns out it is placed nearer the center, when it turns in, farther from the center, than the straight line. The numerical differences for choices of the same type for the two curves are slight, but regular, and the general tendencies are more sharply marked for the line of greater curvature. When Curve II. is 'out,' it is usually nearer the center than Curve I. for the corresponding positions of the straight line; when 'in' it is always farther from the center than Curve I. The greater curvature of II. has clearly produced this difference, and the effect of the curvature in general is evidently to make its side 'lighter' when turned toward the center, and 'heavier' when turned away. Thus, all but the exceptions already noted seem to belong to the mechanically balanced arrangement, in which the suggestion of force working in the direction of the curve has the same effect as, in Exp. IV., the direction of the line. The exceptions noted, especially numerous choices of _O_, seem governed by some fixed law. The evidence would seem to be overwhelming that the reversals of the mechanical balance occur only where the lines would be crowded together in the center or would leave an empty gap there. The remaining exceptions--the symmetrical choices mentioned, made by _C_--are explained by him as follows. He says there are two ways of regarding the curve, (1) as a striving in the direction of the 'bulge,' and (2) as the expression of a power that presses together; and that the usual choices are the result of the first point of view, the symmetrical choices of the second. Naturally, a pressure bending down the line would be conceived as working in a vertical direction, and the line would be treated as another (80×10)--giving, as is the case, symmetrical positions. Thus, we may consider the principle of the suggestion of movement by a curve, as giving the same effect as if the movement suggested had actually taken place, to have been established, the positive evidence being strong, and the exceptions accounted for. It is worth noting that the curve-out series are always more irregular--the subject repeating that it is always harder to choose for that position. Probably the demands of space-filling come into sharper conflict with the tendency to mechanical balance, which for the outward curve would always widely separate the two lines. Exp. V. Curve III. See Fig. 12, III. A series with the upper end turned out from the center was unanimously pronounced as ugly. The inward position only appears in the results, which are given in full. (_a_) F. (80×10), V. CURVE. F. V. O. C. 40 106 126 68 73 80 106 128 109 102 120 140 88 156 110* 154 72* 160 104 66 182 80 136* 130* 200 X 52 178 220* 162 (_b_) F. CURVE, V. (80×10) F. V. O. C. 40 126 122 73 80 80 122 128 66 112* 40 120 90 116 97 156* 55 105 160 65 43 120 182* 87 134 200 70 50 148 66 This curve exemplifies the same principles as the preceding. _O_ takes the natural mechanical choice from (_a_) F. 40 to F. 120, and from (_b_) F. 120 to F. 200. A mechanical choice, however, for (_a_) F. 120 ff., and for (_b_) F. 40 to F. 120, would have brought the lines too far apart in (_a_), and too near together in (_b_), hence the reversal. _C_ inclines always to the mechanical choice, but recognizes the other point of view in his second choices. Exp. V. Curve IV. See Fig. 12, IV. Curve in. (_a_) F. (80×10), V. Curve. _C_ puts V. always further than F. and, even for F. 200, has V. 230, X. _O_ puts V. farther up to F. 120, then puts it nearer than F., and always refuses to choose for F. 200. (_b_) F. Curve, V. (80×10). _C_ always puts V. nearer than F. _O_ puts V. farther for F. 40 and F. 80, beyond that, nearer than F.; but refuses to choose once each for F. 40, and F. 200. The same principles of choice appear. _C_ maintains the mechanical choice, and _O_ reverses it only beyond (_a_) F. 120, and up to (_b_) F. 120, to fill space well, showing his preference for the mechanical choice by changing into it at an unusually early point. Exp. V. Curve V. See Fig. 12, V. Curve in. (_a_) F. (80×10), V. Curve. _C_ puts V. farther than F., except for F. 200, V. 125 and X. _O_ also, changing as usual at F. 120 to V. nearer than F. (_b_) F. Curve, V. (80×10). _O_ puts V. always farther than F. _O_ has V. farther for F. 40 and F. 80, then nearer than F. Refuses to choose for F. 200. Results exactly parallel with those of Curve IV. Comparing all the results of this whole series of experiments on the suggestion of movement, we may conclude that movement, whether suggested by a whole line or part of a line, produces in terms of mechanical balance the same effect that the balanced object would produce after the completion of the suggested motion. This tendency to balance, it appears, lies at the basis of our preference; it often gives way, however, before considerations of space-filling, when the figure which on the scheme of mechanical balance is weaker, gains interest and so 'heaviness' by being brought nearer the center. _D. Experiments on Interest._ By intrinsic interest is meant the interest which would attach to an object quite apart from its place in the space composition. In a picture it would be represented by the interest in an important person, in an unusual object, or in an especially beautiful object, if that beauty were independent of the other forms in the picture--as, for instance, a lovely face, or a jeweled goblet, etc. When the question of the influence of interest on composition came to be discussed, it was found very difficult to abstract the form of the object from the content presented; still more difficult to obtain an effect of interest at all without the entrance of an element of form into the space arrangement. Disembodied intellectual interest was the problem, and the device finally adopted seemed to present, in as indifferent a form as possible, a content whose low degree of absolute interest was compensated for by constant change. Stamps of various countries in black and white reproductions and very small outline pictures on squares of the same size as the stamps were taken as material. The figures were so small in relation to the board that any influence on composition of the lines composing them was impossible; the outline pictures, indeed, gave to the eye which abstracted from their content an impression scarcely stronger than the neighboring blank square. The first set of experiments (VI.) had a small outline picture on the side, and on the other a white paper square of the same size. The necessary interest was given in the form of novelty by changing the picture for every choice. The subjects were _M_, _G_ and _D_. The results were of the same type for each subject and could therefore be averaged. Exp. VI. (1). _(a)_ F. Picture, V. Blank. Eight choices for each. _M_, Average: V. 17 mm. farther from center. _G_, Average: V. 10 mm. farther from center. (Symmetrical position beyond F. 120.) _D_, Average: V. 25.8 mm. farther from center. _(b)_ F. Blank, V. Picture. _M_, Average: V. 33 mm. nearer center. _G_, Average: V. 4 mm. nearer center. (Symmetrical beyond F. 120.) _D_, Average: V. 30 mm. nearer center. (But V. farther at F. 40.) These results are practically unanimous. They show that an object which possesses intrinsic interest acts like a mechanically heavy object, being placed nearer the center than a blank. Two marked deviations from the mechanical choice occur--although they have not affected the average sufficiently to destroy the general harmony of results. _G_, in both _(a)_ and _(b)_, chooses symmetrical positions from F. 120 on. His notes ['_(a)_ F. 140, V. 136, picture unimportant'; '_(b)_ F. 120 and ff., loses relation as they separate'; '_(b)_ F. 160, picture makes no impression'] show clearly that for positions wide apart the picture, already a faint outline, becomes only a white square like the other and is put into geometrical symmetry. Exp. VI. (2), by _G_ and _D_. A stamp on one side unchanged, took the place of the blank; on the other side the stamp was changed for each choice. _(a)_ F. unchanged stamp; V. changed stamp. _D_. Two series, (1) V. always nearer center. (2) Same, except F. 20, V. 52; F. 80, V. 94; F. 140, V. 152; F. 160, V. 175. _G_. Two series. (1) V. much farther from center up to F. 140, then nearer. (2) V. farther throughout, except F. 160, V. 121. _(b)_ F. changed stamp; V. unchanged stamp. _D_. Two series. (1) V. farther up to F. 100, then symmetrical. (2) V. farther up to F. 100, then symmetrical or nearer center. _G_. Two series. (1) V. farther up to F. 120, then symmetrical, and beyond F. 140, nearer center. F. 140, V. 63. (2) V. much farther up to F. 120, then nearer center, but more nearly symmetrical than (1). A complete series of second choices beginning at F. 40, V. slightly nearer center than F. Analyzing results, we find the changed stamp, which has the interest of novelty, nearly always nearer the center than the unchanged. This would indicate a balance of the mechanical type, in which the interest makes an object 'heavier.' The exceptions are in _(a)_ four choices of _D_, _G_ to F. 140, and in _(b)_, _D_'s choice beyond F. 200, and _G_'s beyond F. 120. The deviations are thus seen to be all of the same type: for positions of F. near the center, when a mechanical choice would have brought V. still nearer [(_a_)], it is instead put farther away; for positions of F. far from the center, when a mechanical choice would have put V. still farther away [(_b_)], it is instead brought near. The exceptions are thus fully accounted for by the demand for space-filling. _E. Experiments on Depth._ The experiments on suggestion of depth in the third dimension were as follows. It was desired to contrast two objects differing only with respect to the degree to which they expressed the third dimension. Those objects that do express the third dimension are, in general, views down streets, colonnades, corridors, gates, etc., or, in landscape, deep valleys, vistas between trees, distant mountains, etc. It is evident that representations of products of human handiwork would be less unnatural when isolated for experiment, and two pairs of pictures were accordingly prepared as follows: There was drawn on a square of 80 mm. the picture of the mouth of a railway tunnel, closed tightly by an apparently massive door; and another picture of identical form and surroundings, but showing the rails entering at a slight curve, the deep blackness within, and the small circle of light at the farther end. The second pair consisted of the gateway of a baronial castle, with heraldic bearings and closed iron-wrought doors; and the same gateway open, showing a flagged pavement and an open court with fountain beyond. The perspective effect was heightened by all possible means for both pictures, and care was taken to have the contrast of black and white the same for each pair, so that to the half-shut eye, opened and closed forms seemed to have the same tone. The subjects were directed to try to _feel_ the third dimension as vividly as possible--to project themselves down the vistas, as it were--and then to arrange the squares in the most pleasing manner. The experiments were made by _A_, _M_, _S_, _H_ and _D_. Not all made the same number of repetitions, but as their notes were unusually suggestive, I have made use of all the results, and shall quote the notes for the most part _verbatim_: Exp. VIII. F. Closed Tunnel. V. Open Tunnel. F. V. Subject _H_. 40 90 60 57 80 13 100 12 120 39 140 - 1 160 -32 180 -71, +50 _Notes._--_H_ finds that he neglects the closed tunnel almost entirely, eye is constantly attracted to open tunnel, F. 180, choice of evils. Position of closed tunnel makes the pictures disagreeable. F. 80, V. 13, closed tunnel grows more uninteresting as it goes out, while the open tunnel seems heavier than ever. F. 140, V.-1, closed tunnel loses force and doesn't gain weight. Open tunnel hangs together with the black field beyond it. F. V. Subject _S_. 40 85 95 60 170 195 80 160 180 100 185 200 120 185 - 35, 200 140 85 20 160 115 115 180 100 _Notes._--F. 120, V. 185. After this there is too large a black space between squares, and so a more central position is taken, but there is the necessity of avoiding symmetry, which is displeasing. F. 160, V. 115 is not symmetrical and so is more pleasing. F. 60, V. 195:--the open tunnel holds the eyes, while the other allows them to wander, and so it needs a bigger field on each side. F. 80, V. 180:--a position close together is possible, but it is hard to take them so except as one picture, and that is also difficult. F. 100, V. 200:--there is the same objection to any position which seems to be an acknowledgment of similarity; that is, symmetrical position seems to imply that they are alike, and so is disagreeable. F. 120, V.-35, 200:--now they can be close together because the black tunnel harmonizes with the black to the right, and seems to correspond in distance and depth, while the tunnel 'hangs together' with the black to the left. (Cf. _H_, F. 160, V.--32.) F. 140, V. 20:--when they are together it is difficult to apperceive the frame as a whole; but this position is not far apart, and not disagreeable because the larger stretch of black to the right again hangs together with the tunnel. F. 160, V. 115:--when the open tunnel was in the middle, the closed one seemed to have no business at all, therefore the open tunnel had to be moved over. The only position which was not disagreeable. SUBJECT G. F. V. (1) (2) (3) (4)¹ (5)¹ 40 48 31 36 30 23 60 105 31 40 51 39 80 111 71 60 64 54 100 104 63 78 60 86 120 123 75 91 62 115 140 136 82 111 56 137 160 162 93 148 72 156 180 107 115 181 83 176 ¹Second pair (Court). _Notes._--(1) All quite unsatisfactory. The arrangement difficult to apperceive as a whole. Each picture taken by itself. (2) The tunnel closed doesn't amount to much. (3) The significance of the tunnel gives it weight. For F. 160, V. 148, and F. 180, V. 180, relation difficult. (4) Court closed gets weaker as gets farther from center. (5) At F. 100, begins to lose relation between pictures, as if one were in one room, one in another. SUBJECT A. F. V. (1) (2) (3) (4)² (5)² 40 70 66 140 59 130 60 80 73 159 62 138 80 103 71 120 77 134 100 113 94 108 93 100 120 119 88 96 96 63 140 108 92 60,164 82 43 160 92 118 70 109 50 180 130 154 78 101 50 ²Second pair (Court). _Notes_.--(1) Difficult to apperceive together. From F. 140, V. 108, depth is more strongly imagined. (3) Tunnel closed has not much value. (5) F. 80, V. 134, taken with reference both to frame and to the other picture--must not be symmetrical nor too far out. SUBJECT D. F. V. (1) (2) (3) 40 100 47 38 60 75 60 68 80 104 78 80 100 148, -12 104 120 120 159 166 160 140 182 152, 84, 78 168 160 193 184, -75 180 180 200 - 95, 190 190 _Note_.--F. 100, V.-12; F. 140, V.-52; F. 160, V. -75: they must be close together when on the same side. F. V. (1) (2)¹ Subject M. 40 55 50 60 56 74 80 64 84 100 86 102 120 93 111 140 124 130 160 134 146 180 144 178 ¹Second pair (Court). _Note_.--(1) Quite impossible to take both together; necessary to keep turning from one to the other to get perception of depth together with both. The subjects agree in remarking on the lack of interest of the closed tunnel, and the attractive power of the open tunnel, and notes which emphasize this accompany choices where the open tunnel is put uniformly nearer. (Cf. _H_, F. 180, V. 50; F. 80, V. 13; _G_, (2), (3), (4), (5); _A_, (3), and F. 140.) As a glance at the results shows that the open tunnel is placed on the whole nearer the center, we may conclude that these choices represent a mechanical balance, in which the open tunnel, or depth in the third dimension, is 'heavier.' But another point of view asserts itself constantly in the results of _S_, and scatteringly in those of the others. Analyzing at first only the results of _S_, we find that up to F. 140, with one exception, he places the open tunnel much farther out than the other; and from F. 140 on, nearer. He says, F. 120, V. 185, 'After this there is too large a black space'; that is, in bringing the open tunnel in, he is evidently filling space. But why does he put the open tunnel so far out? It seems that he is governed by the desire for ease in the apperception of the two objects. In his note for F. 80, V. 180, this point of view comes out clearly. He thinks of the objects as being apperceived side by side with the space about each (which apparently takes on the character of its object), and then he seems to balance these two fields. Cf. F. 60, V. 195: 'The closed tunnel allows the eyes to wander, and so it needs a bigger field on each side.' Evidently there is an implication here of the idea of balance. Cf. also F. 120: 'The black tunnel harmonizes with the black to the right, and seems to correspond in distance and depth,' while the closed tunnel 'hangs together with the black on the left.' In brief, the view of F. seems to be that the closed tunnel is less interesting, and partly because it 'allows the eyes to wander,' partly as compensation for the greater heaviness of the open tunnel, it takes with it a larger space than the open tunnel. It is on the whole better to put them apart, because it is more difficult to apperceive them when close together, and so the open tunnel in the earlier choices must, of course, go farther from the center. When these points conflict with the necessity of filling space, the open tunnel comes nearer the center. In general, the notes which emphasize the difficulty of apperceiving the two pictures as flat and deep together accompany choices where the tunnel is put uniformly farther out, or symmetrically. Cf. _G_, (1), (5); _A_, (1); _M_, F. 40, etc. Thus we may continue to separate the two points of view, that of mechanical balance and that of another kind of balance, which we have known heretofore as 'space-filling,' made possible by the power of the center to give 'weight,' but which seems to be now more explicitly recognized as a balancing of 'fields.' At this point we need repeat only, however, that the suggestion of depth in the third dimension seems to confer 'weight,' 'heaviness,' 'balancing power' on its object. Before making a general survey of the results of this chapter, it is necessary to consider a type of choice which has been up to this point consistently neglected--that in which the variable has been placed on the same side of the center as the fixed object. On the theory of balance, either in its simple mechanical form or in its various disguises, this choice would at first seem to be inexplicable. And yet the subjects usually took special pleasure in this choice, when they made it at all. These minus choices are confined to three or four subjects and to two or three experiments. Exp. I. (a) and (b) show the largest number. We have: EXP. I. (_a_) F. (80×10); V. (160×10). F. V. 120 - 44, 160 -150, -105, -88 200 -94, -46, -110 (_b_) F. (160×10); V. (80×10). F. V. 120 -70, -80 160 -114 200 -155, -146, -148 It will be noticed that, with two exceptions, none of the positions chosen are nearer than 70 mm. to the center, and that most of them are much farther away. The two lines seem to be more pleasing when they are pretty close together on the same side. _S_, in I. (_b_) F. 120, V.-70, notes: 'If V. is nearer _O_, there is a tendency to imagine a figure by the connection of the ends of the two lines, which is disagreeable. 'The only other minus choices were in Exp. VII., by _S,_, _H_, and _D_. _S_, F. 120, V.-35, says: 'Now they can be close together,' and _H_, F. 140, 160 and 180, V. -1, -32, -71, notes the same. So also _D_, F. 100, V. -12; F. 140, V. -52; F. 160, V. -75; F. 180, V. -95. It is evident from this insistence on the closeness together of the objects, and this desire to form no figure, that the two are taken as one, and set off against the blackness on the other side. It seems as if this were not taken as empty space, but acquired a meaning of its own. The association with pictures in which the empty space is occupied by a deep vista or an expanse of sky is almost irresistible. The case of Exp. VII. seems a little different. _S_, at least, separates the two fields as usual, but for him also the black space is living, 'corresponds in distance and depth.' It is at least certain that there is no subjective feeling of emptiness or of unoccupied energies on the empty side. And it would seem that some influence from the objects sweeps across the central field and vitalizes it. The most natural view would seem to be that the ease of apperception of the two objects together, and the tendency of the eye movement to begin on the occupied side, and to sweep across to the unoccupied, which we think of as deep, combine to give a feeling of pleasure and of balance. * * * * * We have now reached a point from which a backward glance can be cast upon the territory traversed. Experiment with the isolated elements in pictorial composition has shown that pleasing arrangements of these elements can be interpreted by the formula of mechanical balance. This principle was obtained by opposing two lines whose relative value (corresponding to 'weight' in balance) was known; and it was found that their relative positions corresponded to the relation of the arms of a balance. Further opposition of lines, of which one was already determined in 'weight,' showed the same variations and suggested certain valuations of the undetermined lines on the basis of this common term of weight. Thus, the line suggesting movement out from the center fitted the formula if taken as 'heavy' and _vice versa_, the line suggesting movement in, if taken as 'light.' Similarly, objects of interest and objects suggesting movement in the third dimension were 'heavy' in the same interpretation. But this interpretation, in its baldest form, fitted only a majority of the pleasing arrangements; the minority, in which the consistent carrying out of the lever principle would have left a large unoccupied space in the center, exactly reversed it, bringing the 'light' element to the center and the 'heavy' to the outer edge. Later experiments showed that this choice implied a power in the 'lighter' objects, owing to their central position, to cover or infuse with vitality the empty space about them, so that the principle of balance seemed to maintain itself in one form or another. All this does not go beyond the proof that all pleasing space arrangements can be described in terms of mechanical balance. But what is this mechanical balance? A metaphor, no matter how consistently carried out, explains nothing. The fact that a small object far from the center is usually opposed by a large object near the center tells us nothing of the real forces involved. Physical balance can be explained by principles of mechanics, but no one will maintain that the visual representation of a long line weighs more than that of a short one. Moreover, the elements in the balance seem utterly heterogeneous. The movement suggested by an idea--the picture of a man running--has been treated as if equivalent to the movement actually made by the eye in following a long line; the intrinsic interest--that is, the ideal interest--of an object insignificant in form has been equated to the attractive power of a perspective which has, presumably, a merely physiological effect on the visual mechanism. What justification can be given either of this heterogeneous collection of elements or of the more or less arbitrary and external metaphor by which they have been interpreted? I believe that the required justification of both points of view is given in the reduction of all elements to their lowest term--as objects for the expenditure of attention. A large object and an interesting object are 'heavy' for the same reason, because they call out the attention; a deep perspective, because the eye rests in it;--why, is another question. And expenditure of effort is expenditure of attention; thus, if an object on the outskirts of the field of vision requires a wide sweep of the eye to take it in, it demands the expenditure of attention, and so is felt as 'heavy.' It may be said that involuntary attention is given to the object of intrinsic interest, while the uninteresting object far on the outskirts needs a voluntary effort to perceive it, and that the two attitudes cannot be treated as identical. To this it may be answered that an object on the outskirts of a field of view so definitely limited calls out of itself a reflex movement of the eye toward it, as truly spontaneous as the impulse toward the object of intrinsic interest. But what is 'the expenditure of attention' in physiological terms? It is nothing more than the measure of the motor impulses directed to the object of attention. And whether the motor impulse appears as the tendency to fixate an object or as the tendency to follow out the suggestions of motion in the object, they reduce to the same physiological basis. It may here be objected that our motor impulses are, nevertheless, still heterogeneous, inasmuch as some are _toward_ the object of interest, and some _along_ the line of movement. But it must be said, first, that these are not felt in the body, but transferred as values of weight to points in the picture--it is the amount and not the direction of excitement that is counted; and secondly, that even if it were not so, the suggested movement along a line is felt as 'weight' at a particular point. From this point of view the justification of the metaphor of mechanical balance is quite clear. Given two lines, the most pleasing arrangement makes the larger near the center, and the smaller far from it. This is balanced because the spontaneous impulse of attention to the near, large line, equals in amount the involuntary expenditure of attention to apprehend the small farther one. And this expenditure of motor impulses is pleasing, because it is the type of motor impulses most in harmony with our own physical organism. We may thus think of a space to be composed as a kind of target, in which certain spots or territories count more or less, both according to their distance from the center and according to what fills them. Every element of a picture, in whatever way it gains power to excite motor impulses, is felt as expressing that power in the flat pattern. A noble vista is understood and enjoyed as a vista, but it is _counted_ in the motor equation, our 'balance,' as a spot of so much intrinsic value at such and such a distance from the center. The skilful artist will fill his target in the way to give the maximum of motor impulses with the perfection of balance between them. IV. SYMMETRY IN PICTURES. _A. The Balancing Factors._ The experimental treatment of suggestions as to the elements in pictorial composition has furnished an hypothesis for the basis of our pleasure in a well-composed picture, and for the particular function of each of the several elements. This hypothesis may be expressed as follows: (1) The basis of æsthetic pleasure in composition is a _balance of motor impulses_ on the part of the spectator; (2) this balance of motor impulses is brought about by means of the elements, through the power which they possess of drawing the attention with more or less strength towards a certain field. But to the experimental working out of an hypothesis must succeed a verification, in its application to the masterpieces of civilized art. We have, then, to ask whether there is in all great pictures a balance, _i.e._, an equal distribution of attention on the two sides of the central line suggested by the frame of the picture. It might be, for instance, that a picture of pleasing composition would show, when analyzed, all the attractions for attention on one side; which would go far to impugn either our hypothesis of balance as the basis of pleasure, or our attribution of particular functions to the elements. But as this second matter may be considered to have been sufficiently determined by the results of the preceding section, the first question only remains: Is there a balance of attention in a good picture--or rather, in the particular good pictures known to the student of art? This question could only be answered by the examination of a large number of pictures of accepted merit, and it was also desirable that they should be studied in a form which lent itself to the easy comparison of one picture with another. These conditions seemed to be best fulfilled by the collection of reproductions in black and white known as the _Classischer Bilderschatz_, published by F. Bruckmann, at Munich, which contains over a thousand pictures arranged in schools. Of these a thousand were taken--substantially the first thousand issued, after the frescoes, triptych doors, panels, etc., which are evidently parts of a larger whole, had been laid aside. In the following discussion the pictures will be designated, when they are not further described, by the numbers which they bear in this collection. The equations in the following discussion are based on a system of exact measurement, corresponding to that followed in the experimental section. This numerical treatment is pre-supposed in all the general attributions of balance in the analysis of single pictures. The method of measurement was given by the conditions of viewing pictures, which are framed and thus isolated from surrounding influences, and referred, as compositions, to the middle line suggested by this emphasized frame. An adjustable frame of millimeter paper, divided in half vertically by a white silk thread, was fitted over the picture to be measured, and measurements were made to left and to right of this thread-line and, as required, vertically, by reference to the millimeter frame divisions. The main question, of course, to be answered by a statistical examination of these thousand pictures refers to the existence of balance, but many other problems of symmetry are also seen to be closely involved; the relative frequency of the elements in pictures of different types, and the result of their employment in producing certain emotional effects, also the general types of space arrangement as a whole, the feeling-tone belonging to them, and the relation between content and shape. The first question will not be treated in this paper in the statistical fulness which was necessary to establish my conclusions in the investigation itself, inasmuch as the tables were very extensive. But examples of the tables, together with the full results, will be given, and a sufficient amount of detailed discussion to show my methods. The two other subjects, the use of the elements and the types of composition, will be briefly treated. I expect in other publications to go more closely into statistical detail on these matters than is possible in a merely experimental thesis. In the beginning of the proposed statistical analysis a natural objection must first be forestalled: it will be said, and truly, that color also has its effect in bringing about balance, and that a set of black and white reproductions, therefore, ignores an important element. To this it may be answered, first, that as a matter of fact the color scheme is, as it were, superimposed upon the space-shape, and with a balance of its own, all the elements being interdependent; and secondly, that the black and white does render the intensity contrasts of the colors very well, giving as light and dark, and thus as interesting (= attractive) and the reverse, those factors in the scheme which are most closely related to the complex of motor impulses. After having compared, in European galleries, the originals of very many of these reproductions with the equation of balance worked out from the black and white, the writer has seldom found an essential correction needed. The pictures were first classified by subjects. This may seem less logical than a division by types of arrangement. But it really, for a majority, amounted to the same thing, as the historical masterpieces of art mostly follow conventional arrangements; thus the altarpieces, portraits, genre pictures, etc., were mostly after two or three models, and this classification was of great convenience from every other point of view. The preliminary classification was as follows: (1) Religious, Allegorical and Mythical Pictures; (2) Portraits; (3) Genre; (4) Landscape. The historical pictures were so extremely few that they were included in the religious, as were also all the allegorical pictures containing Biblical persons. Some pictures, of which Watteau's are representative, which hovered between genre and landscape, were finally classified according as they seemed to owe their interest to the figures or to the scenery. A preliminary classification of space arrangements, still with reference to content, showed three large general types: (1) A single subject or group in the middle; (2) the same somewhat on one side, with subordinate elements occupying the rest of the space; (3) two objects or groups each occupying a well-defined center. These were designated as Single Center, Single and Subordinate Center, and Double Center pictures, or S.C., S. & S., and D.C. They are in proportions of S.C. 79 per cent., S. & S. 5 percent., D.C. 16 per cent. The D.C. type is evidently already explicitly balanced as regards shape and intrinsic interest, and is hence of comparative unimportance to our problem. The S.C. will show a balance, if at all, in more or less accessory factors; S. & S., broadly, between interest and other factors. As logically more important, this last group will be treated more fully. The full classification of the thousand pictures by subjects is as follows: S.C. D.C. S.S. Altarpieces 78 70 7 1 Madonna & Child 47 47 0 0 Holy Family 67 40 14 13 Adorations 19 19 0 0 Crucifixions 23 21 0 2 Descents f. Cross 27 26 0 1 Annunciations 21 0 21 0 Misc. Religious 162 93 55 14 Allegorical 46 36 6 4 Genre 93 63 19 11 Landscape 88 65 22 1 Portrait Groups 64 42 17 5 Relig. Single Fig. 28 28 0 0 Alleg. Single Fig. 12 12 0 0 Portrait Single Fig. 207 207 0 0 Genre Single Fig. 18 18 0 0 Altarpieces. The pictures of the first group, consisting of the _Madonna_ and _Infant Christ_ surrounded by worshippers, and briefly designated as Altarpieces, are good for detailed study because they present a simple type, and it will be easy to show whether the variations from symmetry are in the direction of balance or not. A few examples will make this clear. The Madonna in the S.C. pictures is invariably seated holding the Christ. In the following descriptions M. will denote Madonna, C. Child, Cn. central line. The elements, Size or Mass, Direction of Motion or Attention, Direction of Line, Vista, and Interest, will be set down as Ms., D., L., V., and I. A couple of examples will show the method of describing and of drawing a conclusion as to balance. 1. 969. Lorenzo Lotto, _Madonna with St. Bernard and St. Onofrius._ C. is on one side turning to the same; M. leans far to the other; hence interest in C., and direction of C.'s attention are over against Mass of M. and direction of M.'s attention; _i.e._, I. + D. = Ms. + D., and so far, balance. The surrounding saints are insignificant, and we may make the equation I. = Ms. 2. 368. Raffaelino di Francesco, _Madonna Enthroned._ The C. is on Right facing front, M. turns away Left, hence interest in C. is over against direction of M.'s attention. Moreover, all the saints but one turn Left, and of two small vistas behind the throne, the one on the Left is deeper. The superior interest we feel in C. is thus balanced by the tendency of attention to the opposite side, and we have I. = D. + V. It is clear that the broad characteristics of the composition can be symmetrically expressed, so that a classification of the 70 S.C. altarpieces can be made on a basis of these constant elements, in the order of decreasing balance. Thus: Class 1, below, in which the C. is one side of the central line, turned away from the center, the M. turned to the other, balances in these broad lines, or I. + D. = D.; while in (9), I. + D. + D. = (x), the constant elements work all on one side. CLASSIFICATION OF ALTARPIECES. 1 C. one side turned to same, M. to other 11 2 " " " other, " " 8 3 " " " front, " " 2 4 " " " other, M. front. 9 5 " " " facing M. 6 6 " " " front, M. front. 7 7 " " " " M. turned to same. 6 8 " " " to same M. turned front. 7 9 " " " " M. " to same, 14 10 " in middle, turned front. 0 Thus the constant elements, understanding always that C. has more interest than M., are as follows: For (1) I. + D. = D.; (2) I. = D. + D.; (3) I. = D.; (4) I. = D.; (5) I. + D. = D.; etc. These are in order of complete balance, but it will be seen that from (7) on, while the factors are constant, the framework is not balanced; _e.g._ in (9) both I. and D. work on the same side. For these groups, therefore, the variations, if there is balance, will be more striking. Eliminating the balancing elements in the framework, the tables for the ten groups are: (1) I. + D. = D. (2) I. = D. + D(M). (3) I. = D. 969. I. = Ms. 680. I. = D. 1094. Ms. + I. = I. + D. 601. I. = Ms. 735. I. = D. 33. I. = I. + D 49. I. = Ms. + I. 1121. I. = D. 634. I. = Ms. + I. 1035. I. = D. (4) I. = D. 584. I. = I. 333. I. = I. + D. 775. I. = D. 686. I. = I. 80. I. = I. + D. 746. I. = D. 794. I. = D. 753. I. = I. + D. 1106. I. = Ms. + D. 164. I. = D. 1114. I. = D. + L. 781. I. = Ms. + D. 368. I. = D. + V. 1131. I. = I. + D. 927. I. = V. 517. I. = I. + D. 273. I. = V. 327. I. + Ms. = D. + V. 951. I. + L. = D. + V. 715. Unbalanced. (5) I. + D. = D. (6) I. = (7) I. + D. = 43. I. = I. 854. I. = Ms. 725. I. + D. = I. + L. 711. I. = I. 1148. I. = I. 206. I. + D. = I. + L. 447. I. = Ms. 709. I. = D. 155. I. + D. = D. + L. 643. I. = Ms. 907. I. = D. 739. I. + D. = L. 777. I. = Ms. + I. 586. I. = Ms. + I. 331. I. + D. = V. 637. I. = Ms. + I. 137. I. = Ms. + I. 980. Unbalanced. 187. Unbalanced. (8) I. + D. = (9) I. + (D. + D.) = (10) 0. 57. I. + D. = Ms. 835. I. + D. = Ms + I. 979. I. + D. = I. + L. 724. I. + D. = Ms + L. 134. I. + D. = D. 495. I. + D. = Ms + L. 106. I. + D. = D. + V. 182. I. + D. = Ms + V. 220. I. + D. = L. 817. I. + D. = I. 118. I. + D. = V. + L. 662. I. + D. = I. 157. Unbalanced. 806. I. + D. = I. 1136. I. + D. = I. + L. 865. I. + D. = I. + V. 1023. I. + D. = V. 531. I. + D. = L. 553. I. + D. = L. The most used element is I., in 100 per cent. of cases; the least used, V., 13 per cent. D., in 91 per cent. of cases; Ms., 26 per cent.; L., 19 per cent. 175, 433, unbalanced. As seen in the table, a balance of elements is kept, except in four cases which will be hereafter considered. In all cases the balance is between the interest in C., sometimes plus D., (in the attention of the figures to C.), on the one side, and other elements on the other. Very seldom are other salient points found on the C. side. When the C. side is especially 'heavy,' the number of opposing elements increases, and especially takes the form of V. and L. [cf. (7), (8), (9)], which were observed in the experimental chapter to be powerful in attracting attention. For the fairly well-balancing framework--(i), (2), (3) and (4)--Ms., I., and D. are much more often the opposing elements. The pictures listed as unbalanced are, with one exception, among the oldest examples given; conceived in the most slavish geometrical symmetry in which, indeed, the geometrical outline almost hides the fact that the slight variations are all toward a lack of balance. There is but one S. & S. case (1054), Titian, _The Madonna of the House of Pesaro_. In this, M. and C. are on a high throne on the Right, other figures lower down on the Left bearing a flag that leans back to the Left. All the lines of the figures and of the massive architecture and the general direction of attention bear down so strongly to Left that the importance of the Right figures is balanced. We should have, then, I. = I. + L. + D. The D.C. cases, seven in number, are remarkably alike. Six have a vista separating the two groups, in five remarkably deep and beautiful, as if to fix the oscillating attention there. In all, M. and C., either in position or by the direction of their lines, are nearer the Cn. than the opposing figures, which are naturally less interesting, thus giving an instance of the mechanical balance. Their general equation, then, would be I. = M. or M. + L. Having shown that the small variations from the general symmetrical type of altar-pieces are invariably, except in primitive examples, in the direction of substitutional symmetry, or balance, we may next study the Madonna pictures, using the same classifications for purposes of comparison. MADONNA WITH INFANT CHRIST. (1) I. + D. = D. (2) I. = D. + D. (4) I. = D. 56. I. = L. 271. I. = D. + L. 668. I. = D. + Ms. 332. I. = L. 867. I. = D. + V. + D. 14. I. = D. + I. 633. I. = D. 91. I. = D. + V. (3) I. = D. 1111. I. = D. + V. 144. I. = D. 1011. I. = D. = L. 521. I. = D. 915. I. = D. = L. 356. I. = L. + D. + D. 296. I. + Ms. = V. + L. (5) I. + D. = D. (6) I. = 51. I. = D. 596. I. = Ms. 581. I. = D. 892. I. = Ms. 829. I. = D. + I. 224. I. = I. + D. 159. I. = I. + D. 908. I. = D. + L. 683. I. = D. + L. 1045. I. = I. + L. (7) I. + D. = 745. I. = I. + L. 344. I. + D. = Ms. 734. I. = D. + L. 949. I. + D. = Ms. + V. + L. 404. I. = D. + L. 608. I. + D. = L. 248. I. = L. 524. I. + D. = L. 37. I. = L. 97. I. = L. (8) 0. 363. I. = V. + L. 674. I. = V. + L. (9) I. + D. + D. = 62. I. = V. + L. 361. I. + D. = L. 1142. I. = V. + L. 1018. I. = V. + L. (10) 110. I. + V. = Ms. + L. 538. I. = D. 411. I. + V. = Ms. + L. 614. I. + Ms. = V. 771. I. + Ms. = V. + L. 34. D. = Ms. + L. Most used element, I., 100 per cent.; least used, Ms., 21 per cent. D., 96 per cent.; L., 64 per cent.; V., 27 per cent. The first thing to be noted, on comparing this table with the preceding, is the remarkable frequency of the use of the vista and the line. Among the altarpieces, the direction of attention was the element most often opposed to the interesting object; and next to that, another object of interest. These two elements, however, here sink into comparative insignificance. In general, balance is brought about through the disposition of form rather than of interests. This appears in comparing the numbers; against the use of L. in 19 per cent. of the cases among the altarpieces, we have 64 per cent. among the Madonna pictures; V. is used in the former cases 13 per cent. of the times, in the latter 27 per cent. The reason for this would appear to be that the lack of accessories in the person of saints, worshippers, etc., and the consequent increase in the size of M. and C. in the picture heightens the effect of any given outline, and so makes the variations from symmetry greater. This being the case, the compensations would be stronger--and as we have learned that V. and L. are of this character, we see why they are needed. None of the M. and C., S.C. pictures fails to give a complete balance of elements according to hypothesis. There are no well-defined cases of S. & S. or D.C. Portraits. A study of the Madonna pictures of all types, then, results in an overwhelming confirmation of the hypothesis of substitutional symmetry. It may be objected that the generally symmetrical framework of these pictures suggests a complete balance, and the next step in our analysis would, therefore, be a type of picture which is less bound by tradition to the same form. The portrait would seem to combine this desideratum with generally large and simple outlines, so that the whole surface can be statistically reported with comparative ease. A detailed analysis of a couple of portraits may justify the classification adopted. 900. Anton Raphael Mengs, _Self-Portrait_. The head of the painter is exactly in Cn., but is turned sharply to Right, while his shoulders turn Left. His arm and hand are stretched out down to Right, while his other hand, holding pencil, rests on his portfolio to Left. Hence, the D. of attention plus that of L. on Right, balances I. in implements, plus D. of body on Left, or D. + L. = D. + I. 438. B. van der Helst, _Portrait of Paul Potter_. The head of the subject is entirely to Left of Cn., his easel on Right. His body is turned sharply to Right, and both hands, one holding palette and brushes, are stretched down to Right. His full face and frontward glance are on Left. Hence, Ms. + I. in person balances I. in implements + D. of L., or Ms. + I. = I. + L. It is seen that the larger elements in these pictures are the directions of the head and body, and the position of the head, with reference to Cn. The following classification is based on this framework. CLASSIFICATION OF PORTRAITS. A. Head in Cn. I. Body front, head front, 6 II. Body turned, head turned other way, 7 D. = D. III. Body turned, head front, 31 D. = IV. Body front, head turned, 1 D. = V. Body turned, head turned same way, 106 D. + D. = B. Head not in Cn. I. Body turned to empty side, head to same, 18 Ms.=D. II. Body turned to empty side, head front, 23 Ms. = D. III. Body turned to empty side, head to other, 3 Ms. + D. = D. IV. Body front, head front, 2 Ms. = V. Body turned from empty side, head same way, 10 Ms. + D. = This is also in order of less complete balancing of the original elements. The principal characteristics of the different divisions are as follows:-- A. I. (Symmetrical.) Most used element, L.; least used, V. II. (Balanced, D. = D.) Most used element, L.; least used, V. III. (D. = .) Most used element, Ms., in 74 per cent, of cases opposed to D.; in 30 per cent, of cases, D. of glance opposed to D. of body; least used, V. (1 per cent.). IV. One case only. V. (D. = .) Most used element, Ms., in 73 per cent. of cases opposed to D.; in 40 per cent. of cases, D. of glance opposed to D.; in 28 per cent. Ms. + D. of glance opposed to D.; least used element, V. (15 per cent.). I. 39 per cent.; L. 38 per cent. B. I. (Balanced, Ms. + I. = D.) Most used element (not counting those already included in equation), I., 55 per cent.; least used, V., 2 per cent.; L., 50 per cent. In 44 per cent., D. of glance opposed to D. II. (Ms. + I. = D.) Most used element (not in equation), I., 52 per cent. Least used, V., 26 per cent. L., 43 per cent. In 21 per cent., D. of glance opposed to D. III. (Ms. + I. + D. = D.) Three cases. Two cases V. on empty side. IV. (Ms. + I. = .) Two cases. One case V. on empty side. V. (Ms. + I. + D. = .) Most used element, L., 60 per cent.; least used, V., 10 per cent.; 33-1/3 per cent., D. of glance to empty side. The portrait class is an especially interesting object for study, inasmuch as while its general type is very simple and constant, for this very reason the slightest variations are sharply felt, and have their very strongest characteristic effect. We shall, therefore, find that the five principal factors in composition express themselves very clearly. The general type of the portrait composition is, of course, the triangle with the head at the apex, and this point is also generally in the central line--in 73 per cent. of the whole number of cases, as is seen from the table. All cases but one are longer than they are wide, most are half-length or more. Nevertheless, great richness of effect is brought about by emphasizing variations. For instance, the body and head are, in the great majority of cases, turned in the same way, giving the strongest possible emphasis to the direction of attention--especially powerful, of course, where all the interest is in the personality. But it is to be observed that the very strongest suggestion of direction is given by the direction of the glance; and in no case, when most of the other elements are directed in one way, does the glance fail to come backward. (Cf. A. II., V., and B. I., II., V.) A. It is of especial value for our conclusions that that division in which the constant elements are least balanced (V.) is far the most numerous. Comparison of this with III. shows that the principal element, direction of movement of head or body, is balanced by the larger mass of the body or accessories. Very significant, also, is the great increase in the use of V. in this most irregular class (15 per cent. as against 1 per cent. in III.). Three cases (214, 1087, 154, all A.V.,) fail to show substitutional symmetry. B. With the head on one side of Cn., of course the greatest interest is removed to one side, and the element of direction is brought in to balance. Again, with this decrease in symmetry, we see the significant increase in the use of the especially effective elements, V. and L. (Cf. B. I., II., III., IV., and especially V.) In fact, the use of the small deep vista is almost confined to the class with heads not in the middle. The direction of the glance also plays an important part. It is to be noted that in B. I. and II., I. appears as the most frequently used element, exclusive of the general equation, which is, of course, between the mass of the body and interest of the face, on one side, and the direction of suggested movement on the other. This means that very often the direction of movement alone is not sufficient to balance the powerful Ms. + I. of the other side, and that the eye has to be attracted by a definite object of interest. This is usually the hand, with or without an implement--like the palette, etc., of our first examples--or a jewel, vase, or bit of embroidery. This is very characteristic of the portraits of Rembrandt and Van Dyck. In general, it may be said that (1) portraits with the head in the center of the frame show a balance between the direction of suggested movement on one side, and mass or direction of attention, or both together, on the other; while (2) portraits with the head not in the center show a balance between mass and interest on one side, and direction of attention, or of line, or vista, or combinations of these, on the other. The hypothesis of substitutional symmetry is thus completely confirmed. Genre. Still more unsymmetrical in their framework than portraits, in fact the most unfettered type of all, are the genre pictures. Being so irregular, they admit of no complete classification based on constant elements in the framework, such as was possible for the types already dealt with. A grouping, based on types of composition, is indeed possible, as of triangles, diagonals, etc., but as this begs the question of the relative importance of line and direction of attention, and assumes that the shape is all-important, it will not be made use of here. The broad divisions and the relative use of the elements are given as follows: S.C. 63. Most frequent form (I. = or I. + D. =). Most used element, I., 89 per cent.; least used, L., 44 per cent.; D., 57 per cent.; Ms., 57 per cent.; V., 46 per cent. D.C. 19. Most frequent form (I. + D. = I. + D.) Most used element, I. (all cases); least used, L., 31 per cent.; V., 47 per cent.; Ms., 63 per cent.; D., 42 per cent. S.&S. 11. Most frequent form (I. or I. + Ms. = V. or V. +). Most used element, I., 100 per cent.; least used, L., 20 per cent.; V., 82 per cent.; Ms., 72 per cent.; D., 27 per cent. As these are pictures with a human interest, and, therefore full of action and particular points of interest, it was to be expected that I. would be in all forms the element most frequently appearing. In compositions showing great variations from geometrical symmetry, it was also to be expected that V. and L., elements which have been little used up to this point, should suddenly appear in very high percentages; for, as being the most strikingly 'heavy' of the elements, they serve to compensate for other variations combined. In general, however, the balance is between the interesting side, which is also often the most occupied (I. + Ms.), and the direction of suggestion to the other side. For the first time in this investigation the S. & S. and D.C. types appear in appreciable numbers. It is of some significance that the most irregular type of all, S. & S., in which the weight of interest and of mass is overwhelmingly on one side, should be invariably balanced by the third dimension (V.). As these somewhat infrequent cases are especially enlightening for the theory of substitutional symmetry, it is worth while to analyze one in detail. 286. Pieter de Hooch, _The Card-players_, in Buckingham Palace, portrays a group completely on the Right of Cn., all facing in to the table between them. Directly behind them is a high light window, screened, and high on the wall to the extreme Right are a picture and hanging cloaks. All goes to emphasize the height, mass and interest of the Right side. On the Left, which is otherwise empty, is a door half the height of the window, giving on a brightly lighted courtyard, from which is entering a woman, also in light clothing. The light streams in diagonally across the floor. Thus, with all the 'weight' on the Right, the effect of this deep vista on the Left and of its brightness is to give a complete balance, while the suggestion of line from doorway and light makes, together with the central figure, a roughly outlined V, which serves to bind together all the elements. This matter of binding together of elements is reserved for further discussion--the purpose of this detailed description is only to show the extraordinary power of a single element, vista, to balance a whole composition of others, and its significance in the tables as an increasing accompaniment of increasing variations from symmetry. The D.C. cases, inasmuch as they always present a balance of interest at least, are less valuable for our theory; among the variations the larger side, Ms., is often balanced by a vista, or, combining with the usual equation for genre pictures, Ms. + I. + D. = V. + I. + D. There is only one picture which cannot be schematized (263). Landscape. The landscape is another type of unfettered composition. As it represents no action or single object or group of objects, its parts are naturally more or less unconnected. It should, therefore, be said that no picture was taken as D.C. unless there was a distinct separation of the two sides. The typical examples are analyzed in detail. S.C. 912. J. van Ruysdael, _Forest Landscape_, in the London National Gallery. In the Cn. is a stagnant pool, backed on the Right by thick woods. A dead tree, white, very prominent in the Right foreground, another at its foot sloping down to Cn. On the Left a bank sloping down to Cn., a tree at its foot; behind both, and seen also between the two central trees, bright sky and clouds. Thus, there is on the Right, Mass and Direction to Cn.; on the Left, Vista and Direction to Cn.; Ms. + D. = V. + D. D.C. 642. Hobbema, _The Watermill_, in Buckingham Palace. On the Right, a bank sloping upward, a large cluster of trees, a path leading down to Right lower corner. On the Left, somewhat lower, the mill, and water in front of it, flowing down to Left; clearest sky between mill and trees. Thus Mass and Direction out are placed over against Interest (in mill) and Direction out, plus possibly a hint of Vista, or Ms. + D. = I. + D + V. S.C. 65. Most frequent form, Ms. + I. = V. + L. Most used element, V., 98 per cent.; least used, D., 22 per cent. I. 73 per cent.; Ms. 66 per cent.; L. 31 per cent. S. & S. One case. Ms. + I. + V. = V. D.C. 22. Most frequent form, Ms. + I. or Ms. = V. or V. + (almost invariable). Most used element, V., 100 per cent.; least used, D., per cent. Ms. 82 per cent.; I. 73 per cent.; L. 23 per cent. It was, of course, to be expected that in pictures without action there should be little suggestion of attention or of direction of movement. What is less evident is the reason for the high percentage of I. Of course, figures do appear in many examples, and in most pictures some inanimate object is emphasized--as, for instance, the mill in our second example. But the most remarkable point of difference in these tables from the preceding is the presence of V. in practically every example. It is, of course, natural that somewhere in almost every picture there should be a break to show the horizon line, for the sake of variety, if for nothing else--but what is significant is the part played by this break in the balancing of the picture. In about two thirds of the examples the vista is enclosed by lines, or masses, and when near the center, as being at the same time the 'heaviest' part of the picture, serves as a fulcrum or center to bind the parts--always harder to bring together than in the other types of pictures--into a close unity. The most frequent form of this arrangement, as seen by the table, is a diagonal, which just saves itself by turning up at its far end. Thus the mass, and hence usually the special interest of the picture, is on the one side, on the other the vista and the sloping line of the diagonal. In very few cases is the vista behind an attractive or noticeable part of the picture, the fact showing that it acts in opposition to the latter, leading the eye away from it, and thus serving at once the variety and richness of the picture, and its unity. A pure diagonal would have line and vista both working at the extreme outer edge of the picture, and thus too strongly--unless, indeed, balanced by very striking elements near the other edge. This function of the vista as a unifying element is of interest in connection with the theory of Hildebrand,[16] that the landscape should have a narrow foreground and wide background, since that is most in conformity with our experience. He adduces Titian's _Sacred and Profane Love_ as an example. But of the general principle it may be said that not the reproduction of nature, but the production of a unified complex of motor impulses, is the aim of composition, and that this aim is best reached by focusing the eye by a narrow background--_i.e._, vista. No matter how much it wanders, it returns to that central spot and is held there, keeping hold on all the other elements. Of Hildebrand's example it may be said that the pyramidal composition with the dark and tall tree in the center effectually accomplishes the binding together of the two figures, so that a vista is not needed. A wide background without that tree would leave them rather disjointed. [16] A. Hildebrand, 'Das Problem der Form in der Bildenden Kunst,' Strassburg, 1897. Another interesting observation concerns the use of water in landscapes. In nearly all appears an expanse of water, and in four fifths of the cases it is either on the same side as the vista, or in the same line with it. This is no doubt partly due to the light-effects which can be got on the water, but it also greatly reinforces the peculiar effect of the vista. That effect, as has been repeatedly said, is to concentrate, to hold, to fixate vision. The same thing is true of the horizontal line, as was shown by some preliminary experiments not here reported. The contrast to the ordinary trend of lines--particularly in a landscape--together with the strong suggestion of quiet and repose, serve to give the same concentrating effect to the horizontal lines as to the vista. In general, it may be said that balance in landscape is effected between Mass and Interest on one side and Vista and Line on the other; and that unity is given especially by the use of Vista and the horizontal lines of water. A survey of the subject-types remaining on the list of page 514 shows that they may quite well be grouped together with those already examined; that is, the Holy Families, Adorations, Crucifixions, and Annunciations are very symmetrical in type, and present the same characteristics as the Altarpieces. The Miscellaneous (mostly religious) pictures, the Descents, and the Allegorical are, for the most part, freely composed, irregular, full of action, and resemble the genre pictures. The Single Figure pictures, Religious, Allegorical and Genre, and the Portrait Groups, resemble the portraits. Therefore, it may be considered that the existence of a perfect substitutional symmetry has been established, inasmuch as it has been shown to be almost invariably present in the types examined. The experimental treatment of the isolated elements determined the particular function of each in distributing attention in the field of view. The object of large size claims attention, but does not rivet it nor draw it out powerfully; the intrinsically interesting object does excite it, but limits it to a comparatively small field; the suggestion of movement or of attention on the part of pictured objects carries the attention through the field of its operation; the vista rivets the attention without powerfully exciting it, and the line extending in a certain direction carries the attention in the same way as does the suggestion of movement. But the preceding statistical analysis has shown that while all are possibly operative in a given picture, some are given much more importance than others, and that in pictures of different types different elements predominate. The following table gives the distribution of the elements in the single-center pictures already examined. The numbers represent the per cent. of the whole number of balanced pictures in which the given element appears once or more. S.C. Ms. I. D. V. L. Alt. p. 26 100 91 13 31 Mad. 21 100 96 27 64 Port. 80 63 98 17 61 Genre 57 89 57 46 44 Lands. 66 73 22 98 31 It is seen that in those classes with a general symmetrical framework, the altar and Madonna pictures, the elements of interest and direction of attention are overwhelmingly predominant--which is the more to be expected as they appear, of course, as variations in a symmetry which has already, so to speak, disposed of mass and line. They give what action there is, and when they are very strongly operative, we see by page 516, (8) and (9) and note, that they are opposed by salient lines and deep vistas, which act more strongly on the attention than mass; compare further Mad., V. 27 per cent., L. 64 per cent., as against Alt., V. 13 per cent., L. 19 per cent., as confirming the view that they are used in the more irregular and active pictures. But I. keeps its predominance throughout the types, except in the portraits, where, indeed, we should not expect it to be so powerful, since the principal object of interest must always be the portrait head, and that is in most cases in the Cn., and therefore not counted. Yet I. has a respectable representation even in the portrait table, showing that such objects as jewels, embroideries, beautiful hands, etc., count largely too in composition. Its greatest is in the genre table, where, of course, human interests constitute the subject matter. It is among the portraits that the direction of suggestion is most operative. Since these pictures represent no action, it must be given by those elements which move and distribute the attention; in accordance with which we see that line also is unusually influential. As remarked above, the altarpieces and Madonna pictures, also largely without action, depend largely for it on D., in the form of direction of attention (D. 91 per cent.). The vista, as said above, rivets and confines the attention. We can, therefore, understand how it is that in the genre table it suddenly appears very numerous. The active character of these pictures naturally requires to be modified, and the vista introduces a powerful balancing element, which is yet quiet; or, it might be said, inasmuch as energy is certainly expended in plunging down the third dimension, the vista introduces an element of action of counterbalancing character. In the landscape it introduces the principal element of variety. It is always to be found in those parts of the picture which are opposed to other powerful elements, and the 'heavier' the other side, the deeper the vista. This is especially to be noted in all pictures of the S. & S. type, where the one side is very 'heavy' and the deep vista practically invariable on the other. Also in D.C. pictures it serves as a kind of fulcrum, or unifying element, inasmuch as it rivets the attention between the two detached sides. (Cf. D.C. among Alt. and Mad.) The direction of suggestion by means of the indication of a line (L.), quite naturally is more frequent in the Madonna-picture and Portrait classes. Both these types are of large simple outline, so that L. would be expected to tell, but more or less irregular, so that it would not appear on both sides, thus neutralizing its action, as often in the symmetrical altarpieces. This neutralizing explains why it has a comparatively small per cent. in the landscape table, it having appeared in minor form all over the field, but less often in large salient outline. It is worth noticing that for the D.C. of both genre and landscape, the per cent. drops appreciably. As it is, in a decided majority of cases, combined with V.--the shape being more or less a diagonal slope--it is clear that it acts as a kind of bond between the two sides, carrying the attention without a break from one to the other. The element of mass requires less comment. It appears in greatest number in those pictures which have little action, portraits and landscapes, and which are yet not symmetrical--in which last case mass is, of course, already balanced. In fact, it must of necessity exert a certain influence in every unsymmetrical picture, and so its percentage, even for genre pictures, is large. Thus we may regard the elements as both attracting attention to a certain spot and dispersing it over a field. Those types which are of a static character abound in elements which disperse the attention; those which are of a dynamic character, in those which make it stable. The ideal composition seems to combine the dynamic and static elements--to animate, in short, the whole field of view, but in a generally bilateral fashion. The elements, in substitutional symmetry, are then simply means of introducing variety and action. As a dance in which there are complicated steps gives the actor and beholder a varied and thus vivified 'balance,' and is thus more beautiful than the simple walk, so a picture composed in substitutional symmetry is more rich in its suggestions of motor impulse, and thus more beautiful, than an example of geometrical symmetry. _B. Principles of Composition._ The particular function of the elements which are substituted for geometrical symmetry has been made clear; their presence lends variety and richness to the balance of motor impulses. But the natural motor response to stimulation has another characteristic which belongs to us as individuals. The motor response must be balanced, but also unified. In a picture, therefore, there must be a large outline in which all the elements are held together, corresponding to this requirement of unity. Now this way of holding together, this manner of combination, may vary; and I hope to show that it not only varies with the subject and purpose of the picture, but bears a very close relation thereto--that, in short, it is what determines the whole character of the picture. Just what this relation is will appear in the study of our material. Examples of these types of composition may best be found by analyzing a few very well-known pictures. We may begin with the class first studied, the Altarpiece, choosing a picture by Botticelli, in the Florence Academy (746). Under an arch is draped a canopy held up by angels; under this, again, sits the M. with the C. on her lap, on a throne, at the foot of which, on each side, stand three saints. The outline of the whole is markedly pyramidal--in fact, there are, broadly speaking, three pyramids; of the arch, the canopy, and the grouping. A second, much less symmetrical example of this type, is given by another Botticelli in the Academy--_Spring_ (140). Here the central female figure, topped by the floating Cupid, is slightly raised above the others, which, however, bend slightly inward, so that a triangle, or pyramid with very obtuse angle at the apex, is suggested; and the whole, which at first glance seems a little scattered, is at once felt, when this is grasped, as closely bound together. Closely allied to this is the type of the _Madonna of Burgomaster Meyer_, Holbein (725), in the Grand-Ducal Castle, Darmstadt. It is true that the same pyramid is given by the head of the M. against the shell-like background, and her spreading cloak which envelops the kneeling donors. But still more salient is the diamond form given by the descending rows of these worshipping figures, especially against the dark background of the M.'s dress. A second example, without the pyramid backing, is found in Rubens' _Rape of the Daughters of Leucippus_ (88), in the Alte Pinakothek at Munich. Here the diamond shape formed by the horses and struggling figures is most remarkable--an effect of lightness which will be discussed later in interpreting the types. The famous _Bull_ of Paul Potter (149), in the Royal Museum at the Hague, furnishes a third type, the diagonal. High on one side are grouped the herdsman, leaning on a tree which fills up the sky on that side, and his three sheep and cow. The head of the bull is turned toward this side, and his back and hind leg slope down to the other side, as the ground slopes away to a low distant meadow. The picture is thus divided by an irregular diagonal. Somewhat more regular is the diagonal of the _Evening Landscape_, by Cuyp (348), in the Buckingham Palace, London. High trees and cliffs, horsemen and others, occupy one side, and the mountains in the background, the ground and the clouds, all slope gradually down to the other side. It is a natural transition from this type to the V-shape of the landscapes by Aart van der Neer, _Dutch Villages_, 245 and 420, in the London National Gallery and in the Rudolphinum at Prague, respectively. Here are trees and houses on each side, gradually sloping to the center to show an open sky and deep vista. Other examples, of course, show the opening not exactly in the center. In the _Concert_ by Giorgione (758), in the Pitti Gallery, Florence, is seen the less frequent type of the square. The three figures turned toward each other with heads on the same level make almost a square space-shape, although it might be said that the central player gives a pyramidal foundation. This last may also be said of Verrocchio's _Tobias and the Archangels_ in the Florence Academy, for the square, or rather rectangle, is again lengthened by the pyramidal shape of the two central figures. The unrelieved square, it may here be interpolated, is not often found except in somewhat primitive examples. Still less often observed is the oval type of _Samson's Wedding feast_, Rembrandt (295), in the Royal Gallery, Dresden. Here one might, by pressing the interpretation, see an obtuse-angled double-pyramid with the figure of Delilah for an apex, but a few very irregular pictures seem to fall best under the given classification. Last of all it must be remarked that the great majority of pictures show a combination of two or even three types; but these are usually subordinated to one dominant type. Such, for instance, is the case with many portraits, which are markedly pyramidal, with the double-pyramid suggested by the position of the arms, and the inverted pyramid, or V, in the landscape background. The diagonal sometimes just passes over into the V, or into the pyramid; or the square is combined with both. It is, of course, not necessary at this point to show how it is that such an apparently unsymmetrical shape as the diagonal, alone or in combination with other forms, nevertheless produces an effect of balance. In all these cases of the diagonal type the mass or interest of the one side, or the direction of subordinate lines backward to it, balances the impulse of the line descending to the other side. The presence of balance or substitutional symmetry is taken for granted in this treatment, having been previously established, and only the modifications of this symmetry are under consideration. Now, in order to deal properly with the question of the relation of the type of composition to the subject of the picture, complete statistical information will be necessary. A table of the pictures, classified by subjects and distributed under the heads of the six major types, is accordingly subjoined. Pyramid. Double-Pyr. Diagonal. S.C. D.C. S.S. S.C. D.C. S.S. S.C. D.C. S.S. Altarpieces, 49 0 1 10 4 0 1 0 0 Mad. w. C., 40 0 0 7 0 0 0 0 0 Holy Family, 25 0 4 0 0 1 2 2 2 Adorations, 19 0 0 0 0 0 0 0 0 Crucifixions, 11 0 0 7 0 1 0 0 1 Desc. fr. Cross, 12 0 0 3 0 0 1 0 0 Annunciations, 0 8 0 0 4 0 0 0 0 Misc. Religious, 55 16 3 4 4 0 10 7 5 Allegorical, 20 2 1 4 0 0 4 0 2 Genre, 25 4 4 5 0 0 18 2 1 Landscape, 8 2 1 3 0 0 25 6 0 Port. Group, 20 4 2 9 0 0 3 3 2 Rel. Single Fig., 20 0 0 2 0 0 2 0 0 Alleg. S.F., 7 0 0 2 0 0 3 0 0 Portrait S.F., 179 0 0 28 0 0 0 0 0 Genre S.F., 15 0 0 1 0 0 1 0 0 V-shaped. Square. Oval. S.C. D.C. S.S. S.C. D.C. S.S. S.C. D.C. S.S. Altarpieces, 6 1 0 4 1 0 0 1 0 Mad. w. C., 0 0 0 0 0 0 0 0 0 Holy Family, 13 3 6 0 0 0 0 0 0 Adorations, 0 0 0 0 0 0 0 0 0 Crucifixions, 0 0 0 3 0 0 0 0 0 Desc. fr. Cross, 5 0 1 3 0 0 2 0 0 Annunciations, 0 1 0 0 8 0 0 0 0 Misc. Religious, 20 14 2 9 12 1 2 2 3 Allegorical, 3 2 1 3 1 0 3 1 0 Genre, 10 7 6 4 4 0 1 3 0 Landscape, 20 12 0 4 0 0 5 2 0 Port. Group, 10 7 1 0 3 0 0 0 0 Rel. Single Fig., 3 0 0 1 0 0 0 0 0 Alleg. S.F., 0 0 0 0 0 0 0 0 0 Portrait S.F., 0 0 0 0 0 0 0 0 0 Genre S.F., 1 0 0 0 0 0 0 0 0 What types are characteristic of the different kinds of pictures? In order to answer this question we must ask first, What are the different kinds of pictures? One answer, at least, is at once suggested to the student on a comparison of the pictures with their groupings according to subjects. All those which represent the Madonna enthroned, with all variations, with or without saints, shepherds or Holy Family, are very quiet in their action; that is, it is not really an action at all which they represent, but an attitude--the attitude of contemplation. This is no less true of the pictures I have called 'Adorations,' in which, indeed, the contemplative attitude is still more marked. On the other hand, such pictures as the 'Descents,' the 'Annunciations,' and very many of the 'miscellaneous religious,' allegorical and genre pictures, portray a definite action or event. Taking together, for instance, in two groups of five each, the first ten classes in the table, we find that they fall to the six types in the following proportion: P. D.P. Dg. V. Sq. Ov. I. 66 13 05 13 03 0 II. 43 07 14 20 12 04 Inasmuch as II. contains also many 'contemplative' pictures, while I. contains no 'active' ones, the contrast between the proportions of the groups would really be sharper than the figures indicate. But as it is, we see that the pyramid type is characteristic of the 'contemplative' pictures in a much higher degree. If the closely allied double-pyramid type is taken with it, we have 79 per cent of the 'contemplative' to 50 per cent, of the 'active' ones. This view is confirmed by contrasting the 'Adoration,' the most complete example of one group, with the genre pictures, the most complete example of the other--and here we see that in the first all are pyramidal, and in the second only 26 per cent. A class which might be supposed to suggest the same treatment in composition is that of the portraits--absolute lack of action being the rule. And we find, indeed, that no single type is represented within it except the pyramid and double-pyramid, with 86 per cent. of the former. Thus it is evident that for the type of picture which expresses the highest degree of quietude, contemplation, concentration, the pyramid is the characteristic type of composition. But is it not also characteristic of the 'active' pictures, since, as we see, it has the largest representation in that class too? Perhaps it might be said that, inasmuch as all pictures are really more 'quiet' than they are 'active,' so the type _par excellence_ is the pyramidal--a suggestion which is certainly borne out by the table as a whole. But setting aside for the moment the pyramid and its sub-variety, we see that the diagonal V-shaped and square types are much more numerous in the roughly outlined 'active' class. Taking, again, the genre class as especially representative, we find 23 per cent. of the diagonal type, and 25 per cent. of the V-shaped. We have seen how closely allied are these two types, and how gradually one passes over into the other, so that we may for the nonce take them together as making up 47 per cent. of the whole. The type of picture which expresses the highest degree of activity, which aims to tell a story, has, then, for its characteristic type the V and its varieties. The landscape picture presents a somewhat different problem. It cannot be described as either 'active' or 'passive,' inasmuch as it does not express either an attitude or an event. There is no definite idea to be set forth, no point of concentration, as with the altarpieces and the portraits, for instance; and yet a unity is demanded. An examination of the proportions of the types shows at once the characteristic type. P. D.P. Dg. V. Sq. Or. Landscapes, 13 03 35 36 05 08 It is now necessary to ask what must be the interpretation of the use of these types of composition. Must we consider the pyramid the expression of passivity, the diagonal or V, of activity? But the greatly predominating use of the second for landscapes would remain unexplained, for at least nothing can be more reposeful than the latter. It may aid the solution of the problem to remember that the composition taken as a whole has to meet the demand for unity, at the same time that it allows free play to the natural expression of the subject. The altarpiece has to bring about a concentration of attention to express or induce a feeling of reverence. This is evidently brought about by the suggestion of the converging lines to the fixation of the high point in the picture--the small area occupied by the Madonna and Child--and by the subordination of the free play of other elements. The contrast between the broad base and the apex gives a feeling of solidity, of repose; and it seems not unreasonable to suppose that the tendency to rest the eyes above the center of the picture directly induces the associated mood of reverence or worship. Thus the pyramidal form serves two ends; primarily that of giving unity; and secondarily, by the peculiarity of its mass, that of inducing the feeling-tone appropriate to the subject of the picture. Applying this principle to the so-called 'active' pictures, we see that the natural movement of attention between the different 'actors' in the picture must be allowed for, while yet unity is secured. And it is clear that the diagonal type is just fitted for this. The attention sweeps down from the high side to the low, from which it returns through some backward suggestion of lines or interest in the objects of the high side. Action and reaction--movement and return of attention--is inevitable under the conditions of this type; and this it is which allows the free play--which, indeed, _constitutes_ and expresses the activity belonging to the subject, just as the fixation of the pyramid constitutes the quietude of the religious picture. Thus it is that the diagonal composition is particularly suited to portray scenes of grandeur, and to induce a feeling of awe in the spectator, because only here can the eye rove in one large sweep from side to side of the picture, recalled by the mass and interest of the side from which it moves. The swing of the pendulum is here widest, so to speak, and all the feeling-tones which belong to wide, free movement are called into play. If, at the same time, the element of the deep vista is introduced, we have the extreme of concentration combined with the extreme of movement; and the result is a picture in the 'grand style'--comparable to high tragedy--in which all the feeling-tones which wait on motor impulses are, as it were, while yet in the same reciprocal relation, tuned to the highest pitch. Such a picture is the _Finding of the Ring_, Paris Bordone (1048), in the Venice Academy. All the mass and the interest and the suggestion of attention is toward the right--the sweep of the downward lines and of the magnificent perspective toward the left--and the effect of the whole space-composition is of superb largeness of life and feeling. With it may be compared Titian's _Presentation of the Virgin_ (107), also in the Academy, Venice. The composition, from the figure moving upward to one high on the right, to the downward lines, waiting groups and deep vista on the left, is almost identical with that of the Bordone. Neither is pure diagonal--that is, it saves itself at last by an upward movement. Compare also the two great compositions by Veronese, _Martyrdom of St. Mark_, etc. (1091), in the Doge's Palace, Venice, and _Esther before Ahasuerus_ (566), in the Uffizi, Florence. In both, the mass, direction of interest, movement and attention are toward the left, while all the lines tend diagonally to the right, where a vista is also suggested--the diagonal making a V just at the end. Here, too, the effect is of magnificence and vigor. If, then, the pyramid belongs to contemplation, the diagonal to action, what can be said of the type of landscape? It is without action, it is true, and yet does not express that positive quality, that _will_ not to act, of the rapt contemplation. The landscape uncomposed is negative; and it demands unity. Its type of composition, then, must give it something positive besides unity. It lacks both concentration and action; but it can gain them both from a space composition which shall combine unity with a tendency to movement. And this is given by the diagonal and V-shaped type. This type merely allows free play to the natural tendency of the 'active' picture; but it constrains the neutral, inanimate landscape. The shape itself imparts motion to the picture: the sweep of line, the concentration of the vista, the unifying power of the inverted triangle between two masses, act, as it were, externally to the suggestion of the object itself. There is always enough quiet in a landscape--the overwhelming suggestion of the horizontal suffices for that; it is movement that is needed for richness of effect; and, as I have shown, no type imparts the feeling of movement so strongly as the diagonal and V-shaped type of composition. It is worth remarking that the perfect V, which is of course more regular, concentrated, quiet, than the diagonal, is more frequent than the diagonal among the 'Miscellaneous Religious' pictures (that is, it is more _needed_), since after all, as has been said, the final aim of all space composition is just the attainment of repose. But the landscapes need energy, not repression; and so the diagonal type is proportionately more numerous. The square and oval types, as is seen from the table, are far less often used. The oval, most infrequent of all, appears only among the 'active' pictures, with the exception of landscape. It usually serves to unite a group of people among whom there is no one especially striking--or the object of whose attention is in the center of the picture, as in the case of the Descent from the Cross. It imparts a certain amount of movement, but an equable and regular one, as the eye returns in an even sweep from one side to the other. The square type, although only three per cent. of the whole number of pictures, suggests a point of view which has already been touched on in the section on Primitive Art. The examples fall into two classes: in the first, the straight lines across the picture are unrelieved by the suggestion of any other type; in the second, the pyramid or V is suggested in the background with more or less clearness by means of architecture or landscape. In the first class are found, almost exclusively, early examples of Italian, Dutch and German art; in the second, pictures of a later period. The rigid square, in short, is found only at an early stage in the development of composition. Moreover, all the examples are 'story' pictures, for the most part scenes from the lives of the saints, etc. Many of them are double-center--square, that is, with a slight break in the middle, the grouping purely logical, to bring out the relations of the characters. Thus, in the _Dream of Saint Martin_, Simone Martini (325), a fresco at Assisi, the saint lies straight across the picture with his head in one corner. Behind him on one side, stand the Christ and angels, grouped closely together, their heads on the same level. Compare also the _Finding of the Cross_, Piero della Francesca (1088), a serial picture in two parts, with their respective backgrounds all on the same level; and most of the frescoes by Giotto at Assisi--in particular _St. Francis before the Sultan_ (1057), in which the actors are divided into parties, so to speak. These are all, of course, in one sense symmetrical--in the weight of interest, at least--but they are completely amorphous from an æsthetic point of view. The _forms_, that is, do not count at all--only the meanings. The story is told by a clear separation of the parts, and as, in most stories, there are two principal actors, it merely happens that they fall into the two sides of the picture. Interesting in connection with this is the observation that, although the more anecdotal the picture the more likely it is to be 'double-centered,' the later the picture the less likely it is to be double-centered. Thus the square and the double-center composition seem often to be found in the same picture and to be, both, characteristic of early composition. On the other hand, a rigid geometrical symmetry is also characteristic, and these two facts seem to contradict each other. But it is to be noted, first, that the rigid geometrical symmetry belongs only to the Madonna Enthroned, and general Adoration pieces; and secondly, that this very rigidity of symmetry in details can coexist with variations which destroy balance. Thus, in the _Madonna Enthroned_, Giotto (715), where absolute symmetry in detail is kept, the Child sits far out on the right knee of the Madonna. Compare also _Madonna_, Vitale di Bologna (157), in which the C. is almost falling off M.'s arms to the right, her head is bent to the right, and a monk is kneeling at the right lower corner; also _Madonna_, Ottaviano Nelli (175)--all very early pictures. Hence, it would seem that the symmetry of these early pictures was not dictated by a conscious demand for symmetrical arrangement, or rather for real balance, else such failures would hardly occur. The presence of geometrical symmetry is more easily explained as the product, in large part, of technical conditions: of the fact that these pictures were painted as altarpieces to fill a space definitely symmetrical in character--often, indeed, with architectural elements intruding into it. We may even venture to connect the Madonna pictures with the temple images of the classic period, to explain why it was natural to paint the object of worship seated exactly facing the worshipper. Thus we may separate the two classes of pictures, the one giving an object of worship, and thus taking naturally, as has been said, the pyramidal, symmetrical shape, and being moulded to symmetry by all other suggestions of technique; the other aiming at nothing except logical clearness. This antithesis of the symbol and the story has a most interesting parallel in the two great classes of primitive art--the one symbolic, merely suggestive, shaped by the space it had to fill, and so degenerating into the slavishly symmetrical, the other descriptive, 'story-telling' and without a trace of space composition. On neither side is there evidence of direct æsthetic feeling. Only in the course of artistic development do we find the rigid, yet often unbalanced, symmetry relaxing into a free substitutional symmetry, and the formless narrative crystallizing into a really unified and balanced space form. The two antitheses approach each other in the 'balance' of the masterpieces of civilized art--in which, for the first time, a real feeling for space composition makes itself felt. * * * * * THE ÆSTHETICS OF UNEQUAL DIVISION. BY ROSWELL PARKER ANGIER. PART I. The present paper reports the beginnings of an investigation designed to throw light on the psychological basis of our æsthetic pleasure in unequal division. It is confined to horizontal division. Owing to the prestige of the golden section, that is, of that division of the simple line which gives a short part bearing the same ratio to the long part that the latter bears to the whole line, experimentation of this sort has been fettered. Investigators have confined their efforts to statistical records of approximations to, or deviations from, the golden section. This exalts it into a possible æsthetic norm. But such a gratuitous supposition, by limiting the inquiry to the verification of this norm, distorts the results, tempting one to forget the provisional nature of the assumption, and to consider divergence from the golden section as an error, instead of another example, merely, of unequal division. We have, as a matter of fact, on one hand, investigations that do not verify the golden section, and, on the other hand, a series of attempts to account for our pleasure in it, as if it were, beyond dispute, the norm. In this way the statistical inquiries have been narrowed in scope, and interpretation retarded and misdirected. Statistically our aim should be to ascertain within how wide limits æsthetically pleasing unequal divisions fall; and an interpretative principle must be flexible enough to include persistent variations from any hypothetical norm, unless they can be otherwise accounted for. If it is not forced on us, we have, in either case, nothing to do with the golden section. Since Fechner, the chief investigation in the æsthetics of simple forms is that of Witmer, in 1893.[1] Only a small part of his work relates to horizontal division, but enough to show what seems to me a radical defect in statistical method, namely, that of accepting a general average of the average judgments of the several subjects, as 'the most pleasing relation' or 'the most pleasing proportion.'[2] Such a total average may fall wholly without the range of judgments of every subject concerned, and tells us nothing certain about the specific judgments of any one. Even in the case of the individual subject, if he shows in the course of long experimentation that he has two distinct sets of judgments, it is not valid to say that his real norm lies between the two; much less when several subjects are concerned. If averages are data to be psychophysically explained, they must fall well within actual individual ranges of judgment, else they correspond to no empirically determinable psychophysical processes. Each individual is a locus of possible æsthetic satisfactions. Since such a locus is our ultimate basis for interpretation, it is inept to choose, as 'the most pleasing proportion,' one that may have no correspondent empirical reference. The normal or ideal individual, which such a norm implies, is not a psychophysical entity which may serve as a basis of explanation, but a mathematical construction. [1] Witmer, Lightner: 'Zur experimentellen Aesthetik einfacher räumlicher Formverhältnisse,' _Phil. Studien_, 1893, IX., S. 96-144, 209-263. This criticism would apply to judgments of unequal division on either side the center of a horizontal line. It would apply all the more to any general average of judgments including both sides, for, as we shall soon see, the judgments of individuals differ materially on the two sides, and this difference itself may demand its explanation. And if we should include within this average, judgments above and below the center of a vertical line, we should have under one heading four distinct sets of averages, each of which, in the individual cases, might show important variations from the others, and therefore require some variation of explanation. And yet that great leveller, the general average, has obliterated these vital differences, and is recorded as indicating the 'most pleasing proportion.'[3] That such an average falls near the golden section is immaterial. Witmer himself, as we shall see,[4] does not set much store by this coincidence as a starting point for explanation, since he is averse to any mathematical interpretation, but he does consider the average in question representative of the most pleasing division. [2] _op. cit._, 212-215. [3] Witmer: _op. cit._, S. 212-215. [4] _op. cit._, S. 262. I shall now, before proceeding to the details of the experiment to be recorded, review, very briefly, former interpretative tendencies. Zeising found that the golden section satisfied his demand for unity and infinity in the same beautiful object.[5] In the golden section, says Wundt,[6] there is a unity involving the whole; it is therefore more beautiful than symmetry, according to the æsthetic principle that that unification of spatial forms which occurs without marked effort, which, however, embraces the greater manifold, is the more pleasing. But to me this manifold, to be æsthetic, must be a sensible manifold, and it is still a question whether the golden section set of relations has an actual correlate in sensations. Witmer,[7] however, wrote, at the conclusion of his careful researches, that scientific æsthetics allows no more exact statement, in interpretation of the golden section, than that it forms 'die rechte Mitte' between a too great and a too small variety. Nine years later, in 1902, he says[8] that the preference for proportion over symmetry is not a demand for an equality of ratios, but merely for greater variety, and that 'the amount of unlikeness or variety that is pleasing will depend upon the general character of the object, and upon the individual's grade of intelligence and æsthetic taste.' Külpe[9] sees in the golden section 'a special case of the constancy of the relative sensible discrimination, or of Weber's law.' The division of a line at the golden section produces 'apparently equal differences' between minor and major, and major and whole. It is 'the pleasingness of apparently equal differences.' [5] Zelsing, A.: 'Aesthetische Forschungen,' 1855, S. 172; 'Neue Lehre von den Proportionen des menschlichen Körpera,' 1854, S. 133-174. [6] Wundt, W.: 'Physiologische Psychologie,' 4te Aufl., Leipzig, 1893, Bd. II., S. 240 ff. [7] _op. cit._, S. 262. [8] Witmer, L.: 'Analytical Psychology,' Boston, 1902, p. 74. [9] Külpe, O.: 'Outlines of Psychology,' Eng. Trans., London, 1895, pp. 253-255. These citations show, in brief form, the history of the interpretation of our pleasure in unequal division. Zeising and Wundt were alike in error in taking the golden section as the norm. Zeising used it to support a philosophical theory of the beautiful. Wundt and others too hastily conclude that the mathematical ratios, intellectually discriminated, are also sensibly discriminated, and form thus the basis of our æsthetic pleasure. An extension of this principle would make our pleasure in any arrangement of forms depend on the mathematical relations of their parts. We should, of course, have no special reason for choosing one set of relationships rather than another, nor for halting at any intricacy of formulæ. But we cannot make experimental æsthetics a branch of applied mathematics. A theory, if we are to have psychological explanation at all, must be pertinent to actual psychic experience. Witmer, while avoiding and condemning mathematical explanation, does not attempt to push interpretation beyond the honored category of unity in variety, which is applicable to anything, and, in principle, is akin to Zeising's unity and infinity. We wish to know what actual psychophysical functionings correspond to this unity in variety. Külpe's interpretation is such an attempt, but it seems clear that Weber's law cannot be applied to the division at the golden section. It would require of us to estimate the difference between the long side and the short side to be equal to that of the long side and the whole. A glance at the division shows that such complex estimation would compare incomparable facts, since the short and the long parts are separated, while the long part is inclosed in the whole. Besides, such an interpretation could not apply to divisions widely variant from the golden section. This paper, as I said, reports but the beginnings of an investigation into unequal division, confined as it is to results obtained from the division of a simple horizontal line, and to variations introduced as hints towards interpretation. The tests were made in a partially darkened room. The apparatus rested on a table of ordinary height, the part exposed to the subject consisting of an upright screen, 45 cm. high by 61 cm. broad, covered with black cardboard, approximately in the center of which was a horizontal opening of considerable size, backed by opal glass. Between the glass and the cardboard, flush with the edges of the opening so that no stray light could get through, a cardboard slide was inserted from behind, into which was cut the exposed figure. A covered electric light illuminated the figure with a yellowish-white light, so that all the subject saw, besides a dim outline of the apparatus and the walls of the room, was the illuminated figure. An upright strip of steel, 1½ mm. wide, movable in either direction horizontally by means of strings, and controlled by the subject, who sat about four feet in front of the table, divided the horizontal line at any point. On the line, of course, this appeared as a movable dot. The line itself was arbitrarily made 160 mm. long, and 1½ mm. wide. The subject was asked to divide the line unequally at the most pleasing place, moving the divider from one end slowly to the other, far enough to pass outside any pleasing range, or, perhaps, quite off the line; then, having seen the divider at all points of the line, he moved it back to that position which appealed to him as most pleasing. Record having been made of this, by means of a millimeter scale, the subject, without again going off the line, moved to the pleasing position on the other side of the center. He then moved the divider wholly off the line, and made two more judgments, beginning his movement from the other end of the line. These four judgments usually sufficed for the simple line for one experiment. In the course of the experimentation each of nine subjects gave thirty-six such judgments on either side the center, or seventy-two in all. In Fig. 1, I have represented graphically the results of these judgments. The letters at the left, with the exception of _X_, mark the subjects. Beginning with the most extreme judgments on either side the center, I have erected modes to represent the number of judgments made within each ensuing five millimeters, the number in each case being denoted by the figure at the top of the mode. The two vertical dot-and-dash lines represent the means of the several averages of all the subjects, or the total averages. The short lines, dropped from each of the horizontals, mark the individual averages of the divisions either side the center, and at _X_ these have been concentrated into one line. Subject _E_ obviously shows two pretty distinct fields of choice, so that it would have been inaccurate to condense them all into one average. I have therefore given two on each side the center, in each case subsuming the judgments represented by the four end modes under one average. In all, sixty judgments were made by _E_ on each half the line. Letter _E¹_ represents the first thirty-six; _E²_ the full number. A comparison of the two shows how easily averages shift; how suddenly judgments may concentrate in one region after having been for months fairly uniformly distributed. The introduction of one more subject might have varied the total averages by several points. Table I. shows the various averages and mean variations in tabular form. TABLE I. Left. Right. Div. M.V. Div. M.V. _A_ 54 2.6 50 3.4 _B_ 46 4.5 49 5.7 _C_ 75 1.8 71 1.6 _D_ 62 4.4 56 4.1 _E¹_ 57 10.7 60 8.7 _F_ 69 2.6 69 1.6 _G_ 65 3.7 64 2.7 _H_ 72 3.8 67 2.1 _J_ 46 1.9 48 1.3 -- --- -- --- Total 60 3.9 59 3.5 Golden Section = 61.1. ¹These are _E_'s general averages on 36 judgments. Fig. 1, however, represents two averages on each side the center, for which the figures are, on the left, 43 with M.V. 3.6; and 66 with M.V. 5.3. On the right, 49, M.V. 3.1; and 67, M.V. 2.7. For the full sixty judgments, his total average was 63 on the left, and 65 on the right, with mean variations of 9.8 and 7.1 respectively. The four that _E²_ in Fig. 1 shows graphically were, for the left, 43 with M.V. 3.6; and 68, M.V. 5.1. On the right, 49, M.V. 3.1; and 69, M.V. 3.4. [Illustration: FIG. 1.] Results such as are given in Fig. 1, appear to warrant the criticism of former experimentation. Starting with the golden section, we find the two lines representing the total averages running surprisingly close to it. This line, however, out of a possible eighteen chances, only twice (subjects _D_ and _G_) falls wholly within the mode representing the maximum number of judgments of any single subject. In six cases (_C_ twice, _F_, _H_, _J_ twice) it falls wholly without any mode whatever; and in seven (_A_, _B_ twice, _E_, _F_, _G_, _H_) within modes very near the minimum. Glancing for a moment at the individual averages, we see that none coincides with the total (although _D_ is very near), and that out of eighteen, only four (_D_ twice, _G_ twice) come within five millimeters of the general average, while eight (_B_, _C_, _J_ twice each, _F_, _H_) lie between ten and fifteen millimeters away. The two total averages (although near the golden section), are thus chiefly conspicuous in showing those regions of the line that were avoided as not beautiful. Within a range of ninety millimeters, divided into eighteen sections of five millimeters each, there are ten such sections (50 mm.) each of which represents the maximum of some one subject. The range of maximum judgments is thus about one third the whole line. From such wide limits it is, I think, a methodological error to pick out some single point, and maintain that any explanation whatever of the divisions there made interprets adequately our pleasure in unequal division. Can, above all, the golden section, which in only two cases (_D_, _G_) falls within the maximum mode; in five (_A_, _C_, _F_, _J_ twice) entirely outside all modes, and in no single instance within the maximum on both sides the center--can this seriously play the role of æsthetic norm? I may state here, briefly, the results of several sets of judgments on lines of the same length as the first but wider, and on other lines of the same width but shorter. There were not enough judgments in either case to make an exact comparison of averages valuable, but in three successively shorter lines, only one subject out of eight varied in a constant direction, making his divisions, as the line grew shorter, absolutely nearer the ends. He himself felt, in fact, that he kept about the same absolute position on the line, regardless of the successive shortenings, made by covering up the ends. This I found to be practically true, and it accounts for the increasing variation toward the ends. Further, with all the subjects but one, two out of three pairs of averages (one pair for each length of line) bore the same relative positions to the center as in the normal line. That is, if the average was nearer the center on the left than on the right, then the same held true for the smaller lines. Not only this. With one exception, the positions of the averages of the various subjects, when considered relatively to one another, stood the same in the shorter lines, in two cases out of three. In short, not only did the pair of averages of each subject on each of the shorter lines retain the same relative positions as in the normal line, but the zone of preference of any subject bore the same relation to that of any other. Such approximations are near enough, perhaps, to warrant the statement that the absolute length of line makes no appreciable difference in the æsthetic judgment. In the wider lines the agreement of the judgments with those of the normal line was, as might be expected, still closer. In these tests only six subjects were used. As in the former case, however, _E_ was here the exception, his averages being appreciably nearer the center than in the original line. But his judgments of this line, taken during the same period, were so much on the central tack that a comparison of them with those of the wider lines shows very close similarity. The following table will show how _E_'s judgments varied constantly towards the center: AVERAGE. L. R. 1. Twenty-one judgments (11 on L. and 10 on R.) during experimentation on _I¹, I²_, etc., but not on same days. 64 65 2. Twenty at different times, but immediately before judging on _I¹, I²_, etc. 69 71 3. Eighteen similar judgments, but immediately after judging on _I¹, I²_, etc. 72 71 4. Twelve taken after all experimentation with _I¹_, _I²_, etc., had ceased. 71 69 The measurements are always from the ends of the line. It looks as if the judgments in (3) were pushed further to the center by being immediately preceded by those on the shorter and the wider lines, but those in (1) and (2) differ markedly, and yet were under no such influences. From the work on the simple line, with its variations in width and length, these conclusions seem to me of interest. (1) The records offer no one division that can be validly taken to represent 'the most pleasing proportion' and from which interpretation may issue. (2) With one exception (_E_) the subjects, while differing widely from one another in elasticity of judgment, confined themselves severally to pretty constant regions of choice, which hold, relatively, for different lengths and widths of line. (3) Towards the extremities judgments seldom stray beyond a point that would divide the line into fourths, but they approach the center very closely. Most of the subjects, however, found a _slight_ remove from the center disagreeable. (4) Introspectively the subjects were ordinarily aware of a range within which judgments might give equal pleasure, although a slight disturbance of any particular judgment would usually be recognized as a departure from the point of maximum pleasingness. This feeling of potential elasticity of judgment, combined with that of certainty in regard to any particular instance, demands--when the other results are also kept in mind--an interpretative theory to take account of every judgment, and forbids it to seize on an average as the basis of explanation for judgments that persist in maintaining their æsthetic autonomy. I shall now proceed to the interpretative part of the paper. Bilateral symmetry has long been recognized as a primary principle in æsthetic composition. We inveterately seek to arrange the elements of a figure so as to secure, horizontally, on either side of a central point of reference, an objective equivalence of lines and masses. At one extreme this may be the rigid mathematical symmetry of geometrically similar halves; at the other, an intricate system of compensations in which size on one side is balanced by distance on the other, elaboration of design by mass, and so on. Physiologically speaking, there is here a corresponding equality of muscular innervations, a setting free of bilaterally equal organic energies. Introspection will localize the basis of these in seemingly equal eye movements, in a strain of the head from side to side, as one half the field is regarded, or the other, and in the tendency of one half the body towards a massed horizontal movement, which is nevertheless held in check by a similar impulse, on the part of the other half, in the opposite direction, so that equilibrium results. The psychic accompaniment is a feeling of balance; the mind is æsthetically satisfied, at rest. And through whatever bewildering variety of elements in the figure, it is this simple bilateral equivalence that brings us to æsthetic rest. If, however, the symmetry is not good, if we find a gap in design where we expected a filling, the accustomed equilibrium of the organism does not result; psychically there is lack of balance, and the object is æsthetically painful. We seem to have, then, in symmetry, three aspects. First, the objective quantitative equality of sides; second, a corresponding equivalence of bilaterally disposed organic energies, brought into equilibrium because acting in opposite directions; third, a feeling of balance, which is, in symmetry, our æsthetic satisfaction. It would be possible, as I have intimated, to arrange a series of symmetrical figures in which the first would show simple geometrical reduplication of one side by the other, obvious at a glance; and the last, such a qualitative variety of compensating elements that only painstaking experimentation could make apparent what elements balanced others. The second, through its more subtle exemplification of the rule of quantitative equivalence, might be called a higher order of symmetry. Suppose now that we find given, objects which, æsthetically pleasing, nevertheless present, on one side of a point of reference, or center of division, elements that actually have none corresponding to them on the other; where there is not, in short, _objective_ bilateral equivalence, however subtly manifested, but, rather, a complete lack of compensation, a striking asymmetry. The simplest, most convincing case of this is the horizontal straight line, unequally divided. Must we, because of the lack of objective equality of sides, also say that the bilaterally equivalent muscular innervations are likewise lacking, and that our pleasure consequently does not arise from the feeling of balance? A new aspect of psychophysical æsthetics thus presents itself. Must we invoke a new principle for horizontal unequal division, or is it but a subtly disguised variation of the more familiar symmetry? And in vertical unequal division, what principle governs? A further paper will deal with vertical division. The present paper, as I have said, offers a theory for the horizontal. To this end, there were introduced, along with the simple line figures already described, more varied ones, designed to suggest interpretation. One whole class of figures was tried and discarded because the variations, being introduced at the ends of the simple line, suggested at once the up-and-down balance of the lever about the division point as a fulcrum, and became, therefore, instances of simple symmetry. The parallel between such figures and the simple line failed, also, in the lack of homogeneity on either side the division point in the former, so that the figure did not appear to center at, or issue from the point of division, but rather to terminate or concentrate in the end variations. A class of figures that obviated both these difficulties was finally adopted and adhered to throughout the work. As exposed, the figures were as long as the simple line, but of varying widths. On one side, by means of horizontal parallels, the horizontality of the original line was emphasized, while on the other there were introduced various patterns (fillings). Each figure was movable to the right or the left, behind a stationary opening 160 mm. in length, so that one side might be shortened to any desired degree and the other at the same time lengthened, the total length remaining constant. In this way the division point (the junction of the two sides) could be made to occupy any position on the figure. The figures were also reversible, in order to present the variety-filling on the right or the left. If it were found that such a filling in one figure varied from one in another so that it obviously presented more than the other of some clearly distinguishable element, and yielded divisions in which it occupied constantly a shorter space than the other, then we could, theoretically, shorten the divisions at will by adding to the filling in the one respect. If this were true it would be evident that what we demand is an equivalence of fillings--a shorter length being made equivalent to the longer horizontal parallels by the addition of more of the element in which the two short fillings essentially differ. It would then be a fair inference that the different lengths allotted by the various subjects to the short division of the simple line result from varying degrees of substitution of the element, reduced to its simplest terms, in which our filling varied. Unequal division would thus be an instance of bilateral symmetry. The thought is plausible. For, in regarding the short part of the line with the long still in vision, one would be likely, from the æsthetic tendency to introduce symmetry into the arrangement of objects, to be irritated by the discrepant inequality of the two lengths, and, in order to obtain the equality, would attribute an added significance to the short length. If the assumption of bilateral equivalence underlying this is correct, then the repetition, in quantitative terms, on one side, of what we have on the other, constitutes the unity in the horizontal disposition of æsthetic elements; a unity receptive to an almost infinite variety of actual visual forms--quantitative identity in qualitative diversity. If presented material resists objective symmetrical arrangement (which gives, with the minimum expenditure of energy, the corresponding bilateral equivalence of organic energies) we obtain our organic equivalence in supplementing the weaker part by a contribution of energies for which it presents no obvious visual, or objective, basis. From this there results, by reaction, an objective equivalence, for the psychic correlate of the additional energies freed is an attribution to the weaker part, in order to secure this feeling of balance, of some added qualities, which at first it did not appear to have. In the case of the simple line the lack of objective symmetry that everywhere meets us is represented by an unequal division. The enhanced significance acquired by the shorter part, and its psychophysical basis, will engage us further in the introspection of the subjects, and in the final paragraph of the paper. In general, however, the phenomenon that we found in the division of the line--the variety of divisions given by any one object, and the variations among the several subjects--is easily accounted for by the suggested theory, for the different subjects merely exemplify more fixedly the shifting psychophysical states of any one subject. In all, five sets of the corrected figures were used. Only the second, however, and the fifth (chronologically speaking) appeared indubitably to isolate one element above others, and gave uniform results. But time lacked to develop the fifth sufficiently to warrant positive statement. Certain uniformities appeared, nevertheless, in all the sets, and find due mention in the ensuing discussion. The two figures of the second set are shown in Fig. 2. Variation No. III. shows a design similar to that of No. II., but with its parts set more closely together and offering, therefore, a greater complexity. In Table II. are given the average divisions of the nine subjects. The total length of the figure was, as usual, 160 mm. Varying numbers of judgments were made on the different subjects. [Illustration: FIG. 2.] TABLE II. No. I. No. II. No. I. (reversed). No. II. (reversed). L. R. L. R. R. L. R. L. A 55 0 48 0 59 0 50 0 B 59 0 44 0 63 0 52 0 C 58 0 56 0 52 0 50 0 D 60 0 56 0 60 0 55 0 E 74 59 73 65 74 60 75 67 F 61 67 60 66 65 64 62 65 G 64 64 62 68 63 64 53 67 H 76 68 75 64 66 73 67 71 J 49 0 41 0 50 0 42 0 -- -- -- -- -- -- -- -- Total. 61 64 57 65 61 65 54 67 With the complex fillings at the left, it will be seen, firstly, that in every case the left judgment on No. III. is less than that on No. II. With the figures reversed, the right judgments on No. III. are less than on No. II., with the exception of subjects _E_ and _H_. Secondly, four of the subjects only (_E_, _F_, _G_ and _H_) had judgments also on the side which gave the complex filling the larger space; to _E_, _F_ and _G_, these were secondary preferences; to _H_ they were always primary. Thirdly, the judgments on No. III. are less, in spite of the fact that the larger component parts of No. II., might be taken as additional weight to that side of the line, and given, therefore, the shorter space, according to the principle of the lever. The subjects, then, that appear not to substantiate our suggested theory are _E_ and _H_, who in the reversed figures give the shorter space to the less complex filling, and _F_ and _G_, who, together with _E_ and _H_, have always secondary judgments that allot to either complex filling a larger space than to the simple horizontal. Consider, first, subjects _E_ and _H_. For each, the difference in division of II. and III. is in any case very slight. Further, subject _E_, in judgments where the complex filling _exceeds_ the horizontal parallels in length, still gives the more complex of the two fillings markedly the shorter space, showing, apparently, that its additional complexity works there in accord with the theory. There was, according to his introspection, another principle at work. As a figure, he emphatically preferred II. to III. The filling of II. made up, he found, by its greater interest, for lack of length. He here secured a balance, in which the interest of the complex material compensated for the greater _extent_ of the simpler horizontals. This accounts for its small variation from III., and even for its occupying the smaller space. But in judgments giving the two complex fillings the larger space, the more interesting material _exceeded_ in extent the less interesting. In such divisions the balance was no longer uppermost in mind, but the desire to get as much as possible of the interesting filling. To this end the horizontal parallels were shortened as far as they could be without becoming insignificant. But unless some element of balance were there (although not present to introspection) each complex filling, when up for judgment, would have been pushed to the same limit. It, therefore, does seem, in cases where the complex fillings occupied a larger space than the horizontals, that the subject, not trying consciously to secure a balance of _interests_, was influenced more purely by the factor of complexity, and that his judgments lend support to our theory. Subject H was the only subject who consistently _preferred_ to have all complex fillings occupy the larger space. Introspection invariably revealed the same principle of procedure--he strove to get as much of the interesting material as he could. He thought, therefore, that in every case he moved the complex filling to that limit of the pleasing range that he found on the simple line, which would yield him most of the filling. Balance did not appear prominent in his introspection. A glance, however, at the results shows that his introspection is contradicted. For he maintains approximately the same division on the right in all the figures, whether reversed or not, and similarly on the left. The average on the right for all four is 67; on the left it is 74. Comparing these with the averages on the simple line, we see that the right averages coincide exactly, while the left but slightly differ. I suspect, indeed, that the fillings did not mean much to _H_, except that they were 'interesting' or 'uninteresting'; that aside from this he was really abstracting from the filling and making the same judgments that he would make on the simple line. Since he was continually aware that they fell within the 'pleasing range' on the simple line, this conclusion is the more plausible. Perhaps these remarks account for the respective uniformities of the judgments of _E_ and _H_, and their departure from the tendency of the other subjects to give the more complex filling constantly the shorter space. But subjects _F_ and _G_ also had judgments (secondary with both of them) giving to the complex filling a larger extent than to the parallels. With them one of two principles, I think, applies: The judgments are either instances of abstraction from the filling, as with _H_, or one of simpler gravity or vertical balance, as distinguished from the horizontal equivalence which I conceive to be at the basis of the other divisions. With _F_ it is likely to be the latter, since the divisions of the figures under discussion do not approach very closely those of the simple line, and because introspectively he found that the divisions giving the complex the larger space were 'balance' divisions, while the others were determined with 'reference to the character of the fillings.' From _G_ I had no introspection, and the approximation of his judgments to those he gave for the simple line make it probable that with him the changes in the character of the filling had little significance. The average of his judgments in which the complex filling held the greater space is 66, while the averages on the simple line were 65 on the left, and 64 on the right. And, in general, abstraction from filling was easy, and to be guarded against. Subject _C_, in the course of the work, confessed to it, quite unsolicited, and corrected himself by giving thenceforth _all_ complex fillings much smaller space than before. Two others noticed that it was particularly hard not to abstract. Further, none of the four subjects mentioned (with that possible exception of _E_) showed a sensitiveness similar to that of the other five. With the exception of _H_, and in accord with the constant practice of the other five, these subjects, too, occasionally found no pleasing division in which the complex filling preponderated in length over the horizontals. It was uniformly true, furthermore, in every variation introduced in the course of the investigation, involving a complex and a simple filling, that all the nine subjects but _H_ _preferred_ the complex in the shorter space; that five refused any divisions offering it in the larger space; that these five showed more sensitiveness to differences in the character of fillings; and that with one exception (_C_) the divisions of the simple line which these subjects gave were nearer the ends than those of the others. It surely seems plausible that those most endowed with æsthetic sensitiveness would find a division near the center more unequal than one nearer the end; for one side only slightly shorter than the other would at once seem to mean the same thing to them, and yet, because of the obvious difference in length, be something markedly different, and they would therefore demand a part short enough to give them sharp qualitative difference, with, however, in some way, quantitative equivalence. When the short part is too long, it is overcharged with significance, it strives to be two things at once and yet neither in its fulness. We thus return to the simple line. I have considered a series of judgments on it, and a series on two different figures, varying in the degree of complexity presented, in one of their fillings. It remains very briefly to see if the introspection on the simple line furnishes further warrant for carrying the complexities over into the simple line and so giving additional validity to the outlined theory of substitution. The following phrases are from introspective notes. _A_. Sweep wanted over long part. More attention to short. Significance of whole in short. Certainly a concentration of interest in the short. Short is efficacious. Long means rest; short is the center of things. Long, an effortless activity; short, a more strenuous activity. When complex fillings are introduced, subject is helped out; does not have to put so much into the short division. In simple line, subject _introduces_ the concentration. In complex figures the concentration is objectified. In _equal_ division subject has little to do with it; the _unequal_ depends on the subject--it calls for appreciation. Center of references is the division point, and the eye movements to right and left begin here, and here return. The line centers there. The balance is a horizontal affair. _B_. Center a more reposing division. Chief attention to division point, with side excursions to right and left, when refreshment of perception is needed. The balance is horizontal and not vertical. _C_. A balance with variety, or without symmetry. Centers at division point and wants sweep over long part. More concentration on short part. Subjective activity there--an introduction of energy. A contraction of the muscles used in active attention. Long side easier, takes care of itself, self-poised. Line centers at division point. Active with short division. Introduces activity, which is equivalent to the filling that the complex figures have; in these the introduced activity is objectified--made graphic. _D_. Focal point at division point: wants the interesting things in a picture to occupy the left (when short division is also on left). Short division the more interesting and means greater complication. When the pleasing division is made, eyes move first over long and then over short. Division point the center of real reference from which movements are made. _E_. No reference to center in making judgments; hurries over center. All portions of simple line of equal interest; but in unequal division the short gets a non-apparent importance, for the line is then a scheme for the representation of materials of different interest values. When the division is too short, the imagination refuses to give it the proportionally greater importance that it would demand. When too long it is too near equality. In enjoying line, the division point is fixed, with shifts of attention from side to side. An underlying intellectual assignment of more value to short side, and then the sense-pleasure comes; the two sides have then an equality. _F_. Middle vulgar, common, prosaic; unequal lively. Prefers the lively. Eyes rest on division point, moving to the end of long and then of short. Ease, simplicity and restfulness are proper to the long part of complex figures. Short part of simple line looks wider, brighter and more important than long. _G_. Unequal better than equal. Eye likes movement over long and then over short. Subject interested only in division point. Short part gives the æsthetic quality to the line. _H_. Center not wanted. Division point the center of interest. (No further noteworthy introspection from _H_, but concerning complex figures he said that he wanted simple or the compact on the short, and the interesting on the long.) These introspective notes were given at different times, and any repetitions serve only to show constancy. The subjects were usually very certain of their introspection. In general it appears to me to warrant these three statements: (1) That the center of interest is the division point, whence eye-movements, or innervations involving, perhaps, the whole motor system, are made to either side. (2) That there is some sort of balance or equivalence obtained (a bilateral symmetry), which is not, however, a vertical balance--that is, one of weights pulling downwards, according to the principle of the lever. All the subjects repudiated the suggestion of vertical balance. (3) That the long side means ease and simplicity, and represents graphically exactly what it means; that the short side means greater intensity, concentration, or complexity, and that this is substituted by the subject; the short division, unlike the long, means something that it does not graphically represent. So much for the relation between what is objectively given and the significance subjectively attributed to it. There remains still the translation into psychophysical terms. The results on the complex figures (showing that a division may be shortened by making the innervations on that side increasingly more involved) lend plausibility to the interpretation that the additional significance is, in visual terms, a greater intricacy or difficulty of eye-movement, actual or reproduced; or, in more general terms, a greater tension of the entire motor system. In such figures the psychophysical conditions for our pleasure in the unequal division of the simple horizontal line are merely graphically symbolized, not necessarily duplicated. On page 553 I roughly suggested what occurs in regarding the unequally divided line. More exactly, this: the long section of the line gives a free sweep of the eyes from the division point, the center, to the end; or again, a free innervation of the motor system. The sweep the subject makes sure of. Then, with that as standard, the æsthetic impulse is to secure an equal and similar movement, from the center, in the opposite direction. It is checked, however, by the end point of the short side. The result is the innervation of antagonistic muscles, by which the impression is intensified. For any given subject, then, the pleasing unequal division is at that point which causes quantitatively equal physiological discharges, consisting of the simple movement, on one hand, and, on the other, the same kind of movement, compounded with the additional innervation of the antagonists resulting from the resistance of the end point. Since, when the characteristic movements are being made for one side, the other is always in simultaneous vision, the sweep receives, by contrast, further accentuation, and the innervation of antagonists doubtless begins as soon as movement on the short side is begun. The whole of the short movement is, therefore, really a resultant of the tendency to sweep and this necessary innervation of antagonists. The correlate of the equivalent innervations is equal sensations of energy of movement coming from the two sides. Hence the feeling of balance. Hence (from the lack of unimpeded movement on the short side) the feeling there of 'intensity,' or 'concentration,' or 'greater significance.' Hence, too, the 'ease,' the 'simplicity,' the 'placidity' of the long side. As in traditional symmetry, the element of unity or identity, in unequal division, is a repetition, in quantitative terms, on one side, of what is given on the other. In the simple line the _equal_ division gives us obviously exact objective repetition, so that the psychophysical correlates are more easily inferred, while the _unequal_ offers apparently no compensation. But the psychophysical contribution of energies is not gratuitous. The function of the increment of length on one side, which in the centrally divided line makes the divisions equal, is assumed in unequal division by the end point of the short side; the uniform motor innervations in the former become, in the latter, the additional innervation of antagonists, which gives the equality. The two are separated only in degree. The latter may truly be called, however, a symmetry of a higher order, because objectively the disposition of its elements is not graphically obvious, and psychophysically, the quantitative unity is attained through a greater variety of processes. Thus, in complex works of art, what at first appears to be an unsymmetrical composition, is, if beautiful, only a subtle symmetry. There is present, of course, an arithmetically unequal division of horizontal extent, aside from the filling. But our pleasure in this, _without_ filling, has been seen to be also a pleasure in symmetry. We have, then, the symmetry of equally divided extents and of unequally divided extents. They have in common bilateral equivalence of psychophysical processes; the nature of these differs. In both the principle of unity is the same. The variety through which it works is different. * * * * * STUDIES IN ANIMAL PSYCHOLOGY. * * * * * HABIT FORMATION IN THE CRAWFISH CAMBARUS AFFINIS.[1] BY ROBERT M. YERKES AND GURRY E. HUGGINS. [1] See also Yerkes, Robert: 'Habit-Formation in the Green Crab, _Carcinus Granulalus_,' _Biological Bulletin_, Vol. III., 1902, pp. 241-244. This paper is an account of some experiments made for the purpose of testing the ability of the crawfish to profit by experience. It is well known that most vertebrates are able to learn, but of the invertebrates there are several classes which have not as yet been tested. The only experimental study of habit formation in a crustacean which we have found is that of Albrecht Bethe[2] on the crab, _Carcinus maenas_. In his excellent paper on the structure of the nervous system of _Carcinus_ Bethe calls attention to a few experiments which he made to determine, as he puts it, whether the crab possesses psychic processes. The following are the observations made by him. Experiment I. A crab was placed in a basin which contained in its darkest corner an _Eledone_ (a Cephalopod). The crab at once moved into the dark region because of its instinct to hide, and was seized by the _Eledone_ and drawn under its mantle. The experimenter then quickly freed the crab from its enemy and returned it to the other end of the basin. But again the crab returned to the dark and was seized. This was repeated with one animal five times and with another six times without the least evidence that the crabs profited by their experiences with the _Eledone_. Experiment 2. Crabs in an aquarium were baited with meat. The experimenter held his hand above the food and each time the hungry crab seized it he caught the animal and maltreated it, thus trying to teach the crabs that meat meant danger. But as in the previous experiment several repetitions of the experience failed to teach the crabs that the hand should be avoided. From these observations Bethe concludes that _Carcinus_ has no 'psychic qualities' (_i.e._, is unable to profit by experience), but is a reflex machine. [2] Bethe, Albrecht: 'Das Centralnervensystem von _Carcinus maenas_,' II. Theil., _Arch. f. mikr. Anat._, Bd. 51, 1898, S. 447. Bethe's first test is unsatisfactory because the crabs have a strong tendency to hide from the experimenter in the darkest corner. Hence, if an association was formed, there would necessarily be a conflict of impulses, and the region in which the animal would remain would depend upon the relative strengths of its fear of the experimenter and of the _Eledone_. This objection is not so weighty, however, as is that which must obviously be made to the number of observations upon which the conclusions are based. Five or even twenty-five repetitions of such an experiment would be an inadequate basis for the statements made by Bethe. At least a hundred trials should have been made. The same objection holds in case of the second experiment. In all probability Bethe's statements were made in the light of long and close observation of the life habits of _Carcinus_; we do not wish, therefore, to deny the value of his observations, but before accepting his conclusions it is our purpose to make a more thorough test of the ability of crustaceans to learn. [Illustration: FIG. 1. Ground Plan of Labyrinth. _T_, triangular compartment from which animal was started; _P_, partition at exit; _G_, glass plate closing one exit passage. Scale 1/6.] For determining whether the crawfish is able to learn a simple form of the labyrinth method was employed. A wooden box (Fig. 1) 35 cm. long, 24 cm. wide and 15 cm. deep, with one end open, and at the other end a triangular compartment which communicated with the main portion of the box by an opening 5 cm. wide, served as an experiment box. At the open end of this box a partition (_P_) 6 cm. long divided the opening into two passages of equal width. Either of these passages could be closed with a glass plate (_G_), and the subject thus forced to escape from the box by the choice of a certain passage. This box, during the experiments, was placed in the aquarium in which the animals lived. In order to facilitate the movement of the crawfish toward the water, the open end was placed on a level with the water in the aquarium, and the other end was raised so that the box made an angle of 6° with the horizontal. Experiments were made under uniform conditions, as follows. A subject was taken from the aquarium and placed in a dry jar for about five minutes, in order to increase the desire to return to the water; it was then put into the triangular space of the experiment box and allowed to find its way to the aquarium. Only one choice of direction was necessary in this, namely, at the opening where one of the passages was closed. That the animal should not be disturbed during the experiment the observer stood motionless immediately behind the box. Before the glass plate was introduced a preliminary series of tests was made to see whether the animals had any tendency to go to one side on account of inequality of illumination, of the action of gravity, or any other stimulus which might not be apparent to the experimenter. Three subjects were used, with the results tabulated. Exit by Exit by Right Passage Left Passage. No. 1 6 4 No. 2 7 3 No. 3 3 7 16 14 Since there were more cases of exit by the right-hand passage, it was closed with the glass plate, and a series of experiments made to determine whether the crawfish would learn to avoid the blocked passage and escape to the aquarium by the most direct path. Between March 13 and April 14 each of the three animals was given sixty trials, an average of two a day. In Table I. the results of these trials are arranged in groups of ten, according to the choice of passages at the exit. Whenever an animal moved beyond the level of the partition (_P_) on the side of the closed passage the trial was counted in favor of the closed passage, even though the animal turned back before touching the glass plate and escaped by the open passage. TABLE I. HABIT FORMATION IN THE CRAWFISH.¹ Experiments. No. 1 No. 2 No. 3 Totals Per cent Open Closed Open Closed Open Closed Open Closed Open 1-10 8 2 5 5 2 8 15 15 50.0 11-20 4 6 8 2 6 4 18 12 60.0 21-30 6 3² 8 2 8 2 22 7 75.8 31-40 9 1 8 2 8 2 25 5 83.3 41-50 8 2 8 2 7 3 23 7 76.6 51-60 10 0 8 2 9 1 27 3 90.0 TEST OF PERMANENCY OF HABIT AFTER 14 DAYS' REST. 61-70 6 4 8 2 8 2 22 8 73.3 (1-10) 71-80 6 4 8 2 7 3 21 9 70.0 (11-20) ¹The experiments of this table were made by F.D. Bosworth. ²One trial in which the subject failed to return to the water within thirty minutes. In these experiments there is a gradual increase in the number of correct choices (_i.e._, choice of the 'open' passage) from 50 per cent. for the first ten trials to 90 per cent. for the last ten (trials 51-60). The test of permanency, made after two weeks, shows that the habit persisted. Although the observations just recorded indicate the ability of the crawfish to learn a simple habit, it seems desirable to test the matter more carefully under somewhat different conditions. For in the experiments described the animals were allowed to go through the box day after day without any change in the floor over which they passed, and as it was noted that they frequently applied their antennae to the bottom of the box as they moved along, it is possible that they were merely following a path marked by an odor or by moistness due to the previous trips. To discover whether this was really the case experiments were made in which the box was thoroughly washed out after each trip. The nature of the test in the experiments now to be recorded is the same as the preceding, but a new box was used. Fig. 2 is the floor plan and side view of this apparatus. It was 44.5 cm. long, 23.5 cm. wide and 20 cm. deep. The partition at the exit was 8.5 cm. in length. Instead of placing this apparatus in the aquarium, as was done in the previous experiments, a tray containing sand and water was used to receive the animals as they escaped from the box. The angle of inclination was also changed to 7°. For the triangular space in which the animals were started in the preceding tests a rectangular box was substituted, and from this an opening 8 cm. wide by 5 cm. deep gave access to the main compartment of the box. [Illustration: FIG. 2. Floor Plan and Side View of Labyrinth Number 2. _E_, entrance chamber from which animal was started; _C_, cloth covering _E_; _M_, mirror; _T_, tray containing sand and water; _G_, glass plate; _P_, partition; _R_, right exit passage; _L_, left exit passage. Scale 1/8.] A large healthy crawfish was selected and subjected to tests in this apparatus in series of ten experiments given in quick succession. One series a day was given. After each test the floor was washed; as a result the experiments were separated from one another by a three-minute interval, and each series occupied from thirty minutes to an hour. Table II. gives in groups of five these series of ten observations each. The groups, indicated by Roman numerals, run from I. to IX., there being, therefore, 450 experiments in all. Groups I. and II., or the first 100 experiments, were made without having either of the exit passages closed, in order to see whether the animal would develop a habit of going out by one side or the other. It did very quickly, as a matter of fact, get into the habit of using the left passage (L.). The last sixty experiments (Groups I. and II.) show not a single case of escape by the right passage. The left passage was now closed. Group III. gives the result. The time column (_i.e._, the third column of the table) gives for each series of observations the average time in seconds occupied by the animal in escaping from the box. It is to be noted that the closing of the Left passage caused an increase in the time from 30.9 seconds for the last series of the second group to 90 seconds for the first series of the third group. In this there is unmistakable evidence of the influence of the change in conditions. The animal after a very few experiences under the new conditions began going to the Right in most cases; and after 250 experiences it had ceased to make mistakes. Group VII. indicates only one mistake in fifty choices. TABLE II. HABIT FORMATION AND THE MODIFICATION OF HABITS IN THE CRAWFISH. Results in Series of Ten. Avs. in Groups of 50. Series L. R. Time. L. R. L. R. Time. Group I. 1 9 1 45 Per Cent. 2 3 7 69 3 9 1 20 4 4 6 72 5 10 31 -- -- 35 15 70 30 47.4 II. 1 10 29 2 10 30 3 10 30 4 10 28.8 5 10 30.9 -- ---- 50 100 30 .... .... III. 1 4 6 90 2 2 2 8 89.2 1 3 1 9 36.7 1 4 2 8 51 2 5 1 9 43 2 -- -- -- 10 40 7 20 80 62 .... .... IV. 1 3 7 124 1 2 2 8 44 5 3 2 8 37 4 4 10 34 5 2 8 1 -- -- -- 9 41 11 18 82 60 .... .... V. 1 10 44 2 2 10 35 4 3 3 7 76 3 4 2 8 50 7 5 1 9 50 4 -- -- -- 6 44 20 12 88 51 .... .... VI. 1 2 8 45 2 2 10 41 5 3 1 9 41.8 7 4 10 32.7 7 5 10 8 -- -- -- 3 47 29 6 94 40 .... .... VII. 1 1 9 39 4 2 10 38 7 3 10 30.7 3 4 10 42 6 5 10 48 4 -- -- -- 1 49 24 2 98 39.5 R. L. .... .... VIII. 1 8 2 147 1 2 9 1 26 3 8 2 49 2 4 9 1 38 2 5 9 1 41 -- -- -- 43 7 5 86 14 60.2 .... .... IX. 1 1 9 41 2 2 8 39 1 3 10 29 4 1 9 47 5 1 9 32 1 10 90 38 -- -- -- 5 45 2 The dotted lines at the beginning of groups indicate the closed passage. At the beginning of Group VIII. the Right instead of the Left passage was closed in order to test the ability of the animal to change its newly formed habit. As a result of this change in the conditions the animal almost immediately began going to the Left. What is most significant, however, is the fact that in the first trial after the change it was completely confused and spent over fifteen minutes wandering about, and trying to escape by the old way (Fig. 4 represents the path taken). At the end of the preceding group the time of a trip was about 48 seconds, while for the first ten trips of Group VIII. the time increased to 147 seconds. This remarkable increase is due almost entirely to the great length of time of the first trip, in which the animal thoroughly explored the whole of the box and made persistent efforts to get out by the Right passage as it had been accustomed to do. It is at the same time noteworthy that the average time for the second series of Group VIII. is only 26 seconds. For Group IX. the conditions were again reversed, this time the Left passage being closed. Here the first trial was one of long and careful exploration, but thereafter no more mistakes were made in the first series, and in the group of fifty tests there were only five wrong choices. The fifth column, R. L. and L. R., of Table II. contains cases in which the subject started toward one side and then changed its course before reaching the partition. In Group III., for instance, when the Left passage was closed, the subject started toward the Left seven times, but in each case changed to the Right before reaching the partition. This is the best evidence of the importance of vision that these experiments furnish. The first experiments on habit formation proved conclusively that the crawfish is able to learn. The observations which have just been described prove that the labyrinth habit is not merely the following of a path by the senses of smell, taste or touch, but that other sensory data, in the absence of those mentioned, direct the animals. So far as these experiments go there appear to be at least four sensory factors of importance in the formation of a simple labyrinth habit: the chemical sense, touch, vision and the muscle sense. That the chemical sense and touch are valuable guiding senses is evident from even superficial observation, and of the importance of vision and the muscle sense we are certain from the experimental evidence at hand. [Illustration: FIG. 3. Path taken by crawfish while being trained to avoid the left passage. Marks along the glass plate and partition indicate contact by the antennae and chelæ.] Of the significance of the sensations due to the 'direction of turning' in these habits the best evidence that is furnished by this work is that of the following observations. In case of the tests of Table II. the subject was, after 100 preliminary tests, trained by 250 experiences to escape by the Right-hand passage. Now, in Groups III. to VII., the subject's usual manner of getting out of the closed passage, when by a wrong choice it happened to get into it, was to draw back on the curled abdomen, after the antennae and chelæ had touched the glass plate, and then move the chelæ slowly along the Right wall of the partition until it came to the upper end; it would then walk around the partition and out by the open passage. Fig. 3 represents such a course. In Group VIII. the Right passage was closed, instead of the Left as previously. The first time the animal tried to get out of the box after this change in the conditions it walked directly into the Right passage. Finding this closed it at once turned to the Right, _as it had been accustomed to do when it came in contact with the glass plate_, and moved along the side of the box just as it did in trying to get around the end of the partition. The path taken by the crawfish in this experiment is represented in Fig. 4. It is very complex, for the animal wandered about more than fifteen minutes before escaping. The experiment just described to show the importance of the tendency to turn in a certain direction was the first one of the first series after the change in conditions. When given its second chance in this series the subject escaped directly by the Left passage in 33 seconds, and for the three following trips the time was respectively 25, 25 and 30 seconds. Upon the experimental evidence presented we base the conclusion that crawfish are able to profit by experience in much the same way that insects do, but far more slowly. [Illustration: FIG. 4. Path taken by crawfish which had been trained to avoid the Left passage, when the Right passage was closed. Showing turning to the right as in Fig. 3.] It was thought that a study of the way in which crawfish right themselves when placed upon their backs on a smooth surface might furnish further evidence concerning the ability of the animals to profit by experience. Dearborn[3] from some observations of his concludes that there is no one method by which an individual usually rights itself, and, furthermore, that the animals cannot be trained to any one method. His experiments, like Bethe's, are too few to warrant any conclusions as to the possibility of habit formation. [3] Dearborn, G.V.N.: 'Notes on the Individual Psychophysiology of the Crayfish,' _Amer. Jour. Physiol._, Vol. 3, 1900, pp. 404-433. For the following experiments the subject was placed on its back on a smooth surface in the air and permitted to turn over in any way it could. Our purpose was to determine (1) whether there was any marked tendency to turn in a certain way, (2) whether if such was not the case a tendency could be developed by changing the conditions, and (3) how alteration in the conditions of the test would affect the turning. A great many records were taken, but we shall give in detail only a representative series. In Table III., 557 tests made upon four subjects have been arranged in four groups for convenience of comparison of the conditions at different periods of the training process. Each of these groups, if perfect, would contain 40 tests for each of the four subjects, but as a result of accidents II., III., and IV. are incomplete. TABLE III. RE-TURNING OF CRAWFISH. Group. Number of L. R. Time in Tests. Animal. Per cent. Seconds. I. 2 22.5 77.5 14.6 40 3 42.5 57.5 2.6 40 4 52.8 47.2 4.3 38 16 44.5 55.5 22.5 45 -- ---- ---- ---- --- 40.6 59.4 10.8 163 Group. Number of L. R. Time in Tests. Animal. Per cent. Seconds. II 2 28 72 50 43 3 32 68 6.2 50 4 -- 100 6.8 40 16 31.3 68.7 39.3 42 -- ---- ---- ---- --- 22.8 77.2 25.6 175 Group. Number of L. R. Time in Tests. Animal. Per cent. Seconds. III 2 2.5 97.5 46.5 40 -- -- -- -- -- 4 20 80 5.5 40 16 41 59 15 49 -- ---- ---- ---- --- 21.2 78.8 22 129 Group. Number of L. R. Time in Tests. Animal. Per cent. Seconds. IV. 2 2 98 41 50 -- -- -- -- -- 4 32.5 67.5 7.3 40 -- ---- ---- ---- --- 17 83 24 90 Group I., representing 163 tests, shows 59 per cent. to the right, with a time interval of 10.8 seconds (_i.e._, the time occupied in turning). Group II. shows 77 per cent. to the right; and so throughout the table there is an increase in the number of returnings to the right. These figures at first sight seem to indicate the formation of a habit, but in such case we would expect, also, a shortening of the time of turning. It may be, however, that the animals were gradually developing a tendency to turn in the easiest manner, and that at the same time they were becoming more accustomed to the unusual position and were no longer so strongly stimulated, when placed on their backs, to attempt to right themselves. All the subjects were measured and weighed in order to discover whether there were inequalities of the two sides of the body which would make it easier to turn to the one side than to the other. The chelæ were measured from the inner angle of the joint of the protopodite to the angle of articulation with the dactylopodite. The carapace was measured on each side, from the anterior margin of the cephalic groove to the posterior extremity of the lateral edge. The median length of the carapace was taken, from the tip of the rostrum to the posterior edge, and the length of the abdomen was taken from this point to the edge of the telson. These measurements, together with the weights of three of the subjects, are given in the accompanying table. TABLE IV. MEASUREMENTS OF CRAWFISH. Chelæ. Carapace. Abdomen. Weight. Left. Right. Left. Right. Median. No. 2, 9.8 10.0 38.2 38.7 47.3 48.1 29.7 No. 4, 7.7 7.7 33.6 33.8 39.4 42.3 17.7 No. 16, 12.5 12.4 37.6 37.6 46.4 53.2 36.2 Since these measurements indicate slightly greater size on the right it is very probable that we have in this fact an explanation of the tendency to turn to that side. To test the effect of a change in the conditions, No. 16 was tried on a surface slanted at an angle of 1° 12'. Upon this surface the subject was each time so placed that the slant would favor turning to the right. Under these conditions No. 16 gave the following results in two series of tests. In the first series, consisting of 46 turns, 82.6 per cent. were to the right, and the average time for turning was 17.4 seconds; in the second series, of 41 tests, there were 97.5 per cent, to the right, with an average time of 2.5 seconds. We have here an immediate change in the animal's method of re-turning caused by a slight change in the conditions. The subject was now tested again on a level surface, with the result that in 49 tests only 59 per cent. were toward the right, and the time was 15 seconds. SUMMARY. 1. Experiments with crawfish prove that they are able to learn simple labyrinth habits. They profit by experience rather slowly, from fifty to one hundred experiences being necessary to cause a perfect association. 2. In the crawfish the chief factors in the formation of such habits are the chemical sense (probably both smell and taste), touch, sight and the muscular sensations resulting from the direction of turning. The animals are able to learn a path when the possibility of following a scent is excluded. 3. The ease with which a simple labyrinth habit may be modified depends upon the number of experiences the animal has had; the more familiar the animal is with the situation, the more quickly it changes its habits. If the habit is one involving the choice of one of two passages, reversal of the conditions confuses the subject much more the first time than in subsequent cases. 4. Crawfish right themselves, when placed on their backs, by the easiest method; and this is found to depend usually upon the relative weight of the two sides of the body. When placed upon a surface which is not level they take advantage, after a few experiences, of the inclination by turning toward the lower side. * * * * * THE INSTINCTS, HABITS, AND REACTIONS OF THE FROG. BY ROBERT MEARNS YERKES. PART I. THE ASSOCIATIVE PROCESSES OF THE GREEN FROG. I. SOME CHARACTERISTICS OF THE GREEN FROG. The common green frog, _Rana clamitans_, is greenish or brownish in color, usually mottled with darker spots. It is much smaller than the bull frog, being from two to four inches in length ordinarily, and may readily be distinguished from it by the presence of prominent glandular folds on the sides of the back. In the bull frog, _Rana catesbeana_, these folds are very small and indistinct. The green frog is found in large numbers in many of the ponds and streams of the eastern United States, and its peculiar rattling croak may be heard from early spring until fall. It is more active, and apparently quicker in its reactions, than the bull frog, but they are in many respects similar in their habits. Like the other water frogs it feeds on small water animals, insects which chance to come within reach and, in times of famine, on its own and other species of frogs. The prey is captured by a sudden spring and the thrusting out of the tongue, which is covered with a viscid secretion. Only moving objects are noticed and seized; the frog may starve to death in the presence of an abundance of food if there is no movement to attract its attention. Most green frogs can be fed in captivity by swinging pieces of meat in front of them, and those that will not take food in this way can be kept in good condition by placing meat in their mouths, for as soon as the substance has been tasted swallowing follows. The animals used for these experiments were kept in the laboratory during the whole year in a small wooden tank. The bottom of this tank was covered with sand and small stones, and a few plants helped to purify the water. An inch or two of water sufficed; as it was not convenient to have a constant stream, it was changed at least every other day. There was no difficulty whatever in keeping the animals in excellent condition. Of the protective instincts of the green frog which have come to my notice during these studies two are of special interest: The instinctive inhibition of movement under certain circumstances, and the guarding against attack or attempt to escape by 'crouching' and 'puffing.' In nature the frog ordinarily jumps as soon as a strange or startling object comes within its field of vision, but under certain conditions of excitement induced by strong stimuli it remains perfectly quiet, as do many animals which feign death, until forced to move. Whether this is a genuine instinctive reaction, or the result of a sort of hypnotic condition produced by strong stimuli, I am not prepared to say. The fact that the inhibition of movement is most frequently noticed after strong stimulation, would seem to indicate that it is due to the action of stimuli upon the nervous system. What appears to be an instinctive mode of guarding against attack and escaping an enemy, is shown whenever the frog is touched about the head suddenly, and sometimes when strong stimuli are applied to other parts of the body. The animal presses its head to the ground as if trying to dive or dodge something, and inflates its body. This kind of action is supposed to be a method of guarding against the attack of snakes and other enemies which most frequently seize their prey from the front. It is obvious that by pressing its head to the ground the frog tends to prevent any animal from getting it into its mouth, and in the few instants' delay thus gained it is able to jump. This is just the movement necessary for diving, and it is probable that the action should be interpreted in the light of that instinctive reflex. The 'puffing' also would seem to make seizure more difficult. Another fact which favors this interpretation is that the response is most commonly given to stimuli which seem to come from the front and which for this reason could not easily be escaped by a forward jump, while if the stimulus is so given that it appears to be from the rear the animal usually jumps away immediately. We have here a complex protective reaction which may be called a forced movement. It is, so far as one can see, very much like many reflexes, although it does not occur quite so regularly. The machine-like accuracy of many of the frog's actions gives a basis for the belief that the animal is merely an automaton. Certain it is that one is safe in calling almost all the frog's actions reflex or instinctive. During months of study of the reaction-time of the frog I was constantly impressed with the uniformity of action and surprised at the absence of evidences of profiting by experience. In order to supplement the casual observations on the associations of the green frog made in the course of reaction-time experiments, the tests described in this paper were made. They do not give a complete view of the associative processes, but rather such a glimpse as will enable us to form some conception of the relation of the mental life of the frog to that of other animals. This paper presents the outlines of work the details of which I hope to give later. II. EXPERIMENTAL STUDY OF HABITS. A. The Chief Problems for which solutions were sought in the following experimental study were: (1) Those of associability in general, its characteristics, and the rapidity of learning; (2) of discrimination, including the parts played in associative processes by the different senses, and the delicacy of discrimination in each; (3) of the modifiability of associational reactions and general adaptation in the frog, and (4) of the permanency of associations. B. Simple Associations, as studied in connection with reaction-time work, show that the green frog profits by experience very slowly as compared with most vertebrates. The animals have individual peculiarities in reaction which enable one in a short time to recognize any individual. To these characteristic peculiarities they stick tenaciously. One, for instance, always jumps upward when strongly stimulated; another has a certain corner of the tank in which it prefers to sit. Their habits are remarkably strong and invariable, and new ones are slowly formed. While using a large reaction box I noticed that the frogs, after having once escaped from an opening which could be made by pushing aside a curtain at a certain point in the box, tended to return to that place as soon as they were again put into the box. This appeared to be evidence of an association; but the fact that such stimuli as light and the relation of the opening to the place at which the animals were put into the box might in themselves be sufficient to direct the animals to this point without the help of any associations which had resulted from previous experience, makes it unsatisfactory. In addition to the possibility of the action being due to specific sensory stimuli of inherent directive value, there is the chance of its being nothing more than the well-known phenomenon of repetition. Frogs, for some reason, tend to repeat any action which has not proved harmful or unpleasant. For the purpose of more carefully testing this kind of association, a small box with an opening 15 cm. by 10 cm. was arranged so that the animal could escape from confinement in it through the upper part of the opening, the lower portion being closed by a plate of glass 10 cm. by 10 cm., leaving a space 5 cm. by 10 cm. at the top. One subject placed in this box escaped in 5 minutes 42 seconds. After 5 minutes' rest it was given another trial, and this time got out in 2 minutes 40 seconds. The times for a few subsequent trials were: Third, 1 minute 22 seconds; fourth, 4 minutes 35 seconds; fifth, 2 minutes 38 seconds; sixth, 3 minutes 16 seconds. Although this seems to indicate some improvement, later experiments served to prove that the frogs did not readily form any associations which helped them to escape. They tended to jump toward the opening because it was light, but they did not learn with twenty or thirty experiences that there was a glass at the bottom to be avoided. Thinking that there might be an insufficient motive for escape to effect the formation of an association, I tried stimulating the subject with a stick as soon as it was placed in the box. This frightened it and caused violent struggles to escape, but instead of shortening the time required for escape it greatly lengthened it. Here was a case in which the formation of an association between the appearance of the upper part of the clear space and the satisfaction of escape from danger would have been of value to the frog, yet there was no evidence of adaptation to the new conditions within a reasonably short time. There can be little doubt that continuation of the training would have served to establish the habit. This very clearly shows the slowness of adaptation in the frog, in contrast with the rapidity of habit formation in the cat or chick; and at the same time it lends additional weight to the statement that instinctive actions are all-important in the frog's life. A few things it is able to do with extreme accuracy and rapidity, but to this list new reactions are not readily added. When put within the box described, an animal after having once escaped would sometimes make for the opening as if it knew perfectly the meaning of the whole situation, and yet the very next trial it would wander about for half an hour vainly struggling to escape. A considerable number of simple experiments of this kind were tried with results similar to those just given. The frog apparently examines its surroundings carefully, and just when the observer thinks it has made itself familiar with the situation it reacts in such a way as to prove beyond doubt the absence of all adaptation. In all these experiments it should be said, for the benefit of any who may be trying similar work, that only animals of exceptional activity were used. Most green frogs when placed in the experiment box either sit still a great part of the time or jump about for only a short time. It is very important for studies of this kind, both on account of time saving and the obtaining of satisfactory records, to have animals which are full of energy and eager to escape when in confinement. By choosing such subjects one may pretty certainly avoid all unhealthy individuals, and this, it seems to me, counterbalances the disadvantage of taking animals which may be unusually quick in learning. C. Complex Associations. 1. _Labyrinth Habits_.--A more thorough investigation of the associative processes, sensory discrimination and the permanency of impressions has been made by the labyrinth method. A wooden box, 72 cm. long, 28 cm. wide and 28 cm. deep, whose ground plan is represented by Fig. 1, served as the framework for a simple labyrinth. At one end was a small covered box, _A_, from which the frog was allowed to enter the labyrinth. This entrance passage was used in order that the animal might not be directed to either side by the disturbance caused by placing it in the box. _E_, the entrance, marks a point at which a choice of directions was necessary. _P_ is a movable partition which could be used to close either the right or the left passage. In the figure the right is closed, and in this case if the animal went to the right it had to turn back and take the left passage in order to get out of the box. A series of interrupted electrical circuits, _IC_, covered the bottom of a portion of the labyrinth; by closing the key, _K_, the circuit could be made whenever a frog rested upon any two wires of the series. When the frog happened to get into the wrong passage the key was closed and the animal stimulated. This facilitated the experiment by forcing the animal to seek some other way of escape, and it also furnished material for an association. Having passed through the first open passage, which for convenience we may know as the entrance passage, the animal had to choose again at the exit. Here one of the passages was closed by a plate of glass (in the figure the left) and the other opened into a tank containing water. The box was symmetrical and the two sides were in all respects the same except for the following variable conditions. At the entrance the partition on one side changed the appearance, as it was a piece of board which cut off the light. On either side of the entrance there were grooves for holding card-boards of any desired color. The letters _R, R_ mark sides which in this case were covered with red; _W, W_ mark white spaces. These pieces of cardboard could easily be removed or shifted at any time. At the exit the glass plate alone distinguished the sides, and it is not likely that the animals were able to see it clearly. We have thus at the entrance widely differing appearances on the two sides, and at the exit similarity. The opening from _A_ into the large box was provided with a slide door so that the animal could be prevented from returning to _A_ after entering the labyrinth. The partitions and the triangular division at the entrance extended to the top of the box, 28 cm., so that the animals could not readily jump over them. [Illustration: FIG. 1. Ground Plan of Labyrinth. _A_, small box opening into labyrinth; _E_, entrance of labyrinth; _T_, tank containing water; _G_, glass plate closing one passage of exit; _P_, partition closing one passage at entrance; _IC_, interrupted electrical circuit; _C_, cells; _K_, key in circuit; _RR_, red cardboard; _WW_, white cardboard. Scale 1/12.] The experiments were made in series of ten, with ten-minute intervals between trials. In no case was more than one series a day taken, and wherever a day was missed the fact has been indicated in the tables. The only motive of escape from the box depended upon was the animal's desire to return to the water of the tank and to escape from confinement in the bright light of the room. The tank was one in which the frogs had been kept for several months so that they were familiar with it, and it was as comfortable a habitat as could conveniently be arranged. Usually the animals moved about almost constantly until they succeeded in getting out, but now and then one would remain inactive for long intervals; for this reason no record of the time taken for escape was kept. On account of the great amount of time required by experiments of this kind I have been unable to repeat this series of experiments _in toto_ on several animals in order to get averages, but what is described for a representative individual has been proved normal by test observations on other animals. There are very large individual differences, and it may well be that the subject of the series of experiments herein described was above the average in ability to profit by experience. But, however that may be, what is demonstrated for one normal frog is thereby proved a racial characteristic, although it may be far from the mean condition. Before beginning training in the labyrinth, preliminary observations were made to discover whether the animals had any tendencies to go either to the right or to the left. When the colored cardboards were removed it was found that there was usually no preference for right or left. In Table I. the results of a few preliminary trials with No. 2 are presented. For these the colors were used, but a tendency to the right shows clearly. Trials 1 to 10 show choice of either the right or the red throughout; that it was partly both is shown by trials 11 to 30, for which the colors were reversed. This individual has therefore, to begin with, a tendency to the right at the entrance. At the exit it went to the right the first time and continued so to do for several trials, but later it learned by failure that there was a blocked passage as well as an open one. In the tables the records refer to choices. It was useless to record time or to lay much stress upon the course taken, as it was sometimes very complicated; all that is given, therefore, is the action in reference to the passages. _Right_ in every case refers to the choice of the open way, and _wrong_ to the choice of the blocked passage. The paths taken improved steadily in that they became straighter. A few representative courses are given in this report. Usually if the animal was not disturbed a few jumps served to get it out of the labyrinth. TABLE I. PRELIMINARY TRIALS WITH FROG NO. 2. Trials. Red on Right. White on Left. 1 to 10 10 times to red 0 Red on Left. White on Right. 11 to 20 4 times to red 6 Red on Left. White on Right. 21 to 30 3 times to red 7 To Red. To White. To Right. To Left. Totals. 17 13 23 7 This table indicates in trials 1 to 10 a strong tendency to the red cardboard. Trials 21 to 30 prove that there was also a tendency to the right. Training was begun with the labyrinth arranged as shown in Fig. 1, that is, with the left entrance passage and the right exit passage open, and with red cardboard on the right (red was always on the side to be avoided) and white on the left. Table II. contains the results of 110 trials with No. 2, arranged according to right and wrong choice at the entrance and exit. Examination of this table shows a gradual and fairly regular increase in the number of right choices from the first series to the last; after 100 experiences there were practically no mistakes. With another subject, No. _6a_, the results of Table III. were obtained. In this instance the habit formed more slowly and to all appearances less perfectly. Toward the end of the second week of work _6a_ showed signs of sickness, and it died within a few weeks, so I do not feel that the experiments with it are entirely trustworthy. During the experiments it looked as if the animal would get a perfectly formed habit very quickly, but when it came to the summing up of results it was obvious that there had been little improvement. [Illustration: FIG. 2. Labyrinth as arranged for experiments. _E_, entrance; _R, R_, regions covered with red; _W, W_, regions covered with white. The tracing represents the path taken by No. 2 on the sixth trial. Dots mark jumps.] TABLE II. LABYRINTH HABIT. FROG NO. 2. Entrance. Exit. Remarks. Trials. Right. Wrong. Right. Wrong. 1- 10 1 9 4 6 One day rest. 11- 20 2 8 5 5 21- 30 4 6 7 3 31- 40 5 5 6 4 41- 50 5 5 6 2 (17) (33) (30) (20) 51- 60 9 1 8 2 61- 70 6 4 10 0 71- 80 7 3 9 1 81- 90 9 1 8 2 91-100 10(50) 0(10) 10(52) 0( 8) --- --- --- --- 67 43 82 28 Other animals which were used gave results so similar to those for frog No. 2 that I feel justified in presenting the latter as representative of the rapidity with which the green frog profits by experience. TABLE III. LABYRINTH HABIT. FROG NO. _6a_. Entrance. Exit. Remarks. Trials Right. Wrong. Right. Wrong. 1- 10 6 4 5 5 One day rest. 11- 20 7 3 4 6 21- 30 2 8 1 9 31- 40 6 4 1 9 41- 50 7 3 8 2 (28) (22) (19) (31) 51- 60 5 5 7 3 61- 70 6 4 4 6 71- 80 4 6 3 7 One day rest. 81- 90 5 5 7 3 91-100 10(30) 0(20) 8(29) 2(21) ---- ---- ---- ---- (58) (44) (48) (52) Preliminary Trials. Red on Left Partition at Exit on Right 1- 5 5 times to Red 4 times to Partition. Red on Right Partition at Exit on Left 6-10 3 times to Red 5 times to Partition. 2. _Rapidity of Habit Formation_.--As compared with other vertebrates whose rapidity of habit formation is known, the frog learns slowly. Experimental studies on the dog, cat, mouse, chick and monkey furnish excellent evidence of the ability of these animals to profit quickly by experience through the adapting of their actions to new conditions. They all show marked improvement after a few trials, and after from ten to thirty most of them have acquired perfect habits. But the comparison of the frog with animals which are structurally more similar to it is of greater interest and value, and we have to inquire concerning the relation of habit formation in the frog to that of fishes and reptiles. Few experimental studies with these animals have been made, and the material for comparison is therefore very unsatisfactory. E.L. Thorndike[1] has demonstrated the ability of fishes to learn a labyrinth path. In his report no statement of the time required for the formation of habit is made, but from personal observation I feel safe in saying that they did not learn more quickly than did the frogs of these experiments. Norman Triplett[2] states that the perch learns to avoid a glass partition in its aquarium after repeatedly bumping against it. Triplett repeated Moebius' famous experiment, and found that after a half hour's training three times a week for about a month, the perch would not attempt to capture minnows which during the training periods had been placed in the aquarium with the perch, but separated from them by a glass partition. Triplett's observations disprove the often repeated statement that fishes do not have any associative processes, and at the same time they show that the perch, at least, learns rapidly--not so rapidly, it is true, as most animals, but more so in all probability than the amphibia. [1] Thorndike, Edward: 'A Note on the Psychology of Fishes,' _American Naturalist_. 1899, Vol. XXXIII., pp. 923-925. [2] Triplett, Norman: 'The Educability of the Perch,' _Amer. Jour. Psy._, 1901, Vol. XII., pp. 354-360. The only quantitative study of the associative processes of reptiles available is some work of mine on the formation of habits in the turtle.[3] In the light of that study I can say that the turtle learns much more rapidly than do fishes or frogs. Further observations on other species of turtles, as yet unpublished, confirm this conclusion. [3] Yerkes, Robert Mearns: 'The Formation of Habits in the Turtle,' _Popular Science Monthly_, 1901, Vol. LVIII., pp. 519-535. For the frog it is necessary to measure and calculate the improvement in order to detect it at first, while with the turtle or chick the most casual observer cannot fail to note the change after a few trials. In connection with the quickness of the formation of associations it is of interest to inquire concerning their permanency. Do animals which learn slowly retain associations longer? is a question to which no answer can as yet be given, but experiments may readily be made to settle the matter. I have tested the frog for permanency, and also the turtle, but have insufficient data for comparison. 3. _Sensory Data Contributing to the Associations_.--Among the most important of the sensory data concerned in the labyrinth habit are the visual impressions received from the different colored walls, the slight differences in brightness of illumination due to shadows from the partitions and the contrast in form of the two sides of the labyrinth resulting from the use of the partitions, and the muscular sensations dependent upon the direction of turning. The experiments proved beyond question that vision and the direction of turning were the all-important factors in the establishment of the habit. At first it seemed as if the direction of turning was the chief determinant, and only by experimenting with colors under other conditions was I able to satisfy myself that the animals did notice differences in the appearance of their surroundings and act accordingly. In Table IV. some results bearing on this point have been arranged. To begin with, the habit of going to the left when the red was on the right at the entrance had been established; then, in order to see whether the colors influenced the choice, I reversed the conditions, placing the red on the left, that is, on the open-passage side. The results as tabulated in the upper part of Table IV. show that the animals were very much confused by the reversal; at the entrance where there were several guiding factors besides the colors there were 50 per cent. of mistakes, while at the exit where there were fewer differences by which the animal could be directed it failed every time. This work was not continued long enough to break up the old habit and replace it by a new one, because I wished to make use of the habit already formed for further experiments, and also because the animals remained so long in the labyrinth trying to find their way out that there was constant danger of losing them from too prolonged exposure to the dry air. TABLE IV. INFLUENCE OF CHANCES OF CONDITIONS. FROG NO. 2. Habit perfectly formed of going to Left (avoiding Red) at entrance and to Right at exit. Conditions now reversed. Red on Left. Partition at Exit on Right. Trials. Entrance. Exit. Remarks. Right. Wrong. Right. Wrong. 1- 5 3 2 0 5 6-10 2 3 0 5 Discontinued because animal remained so long in labyrinth that there was danger of injuring it for further work. This shows that the habit once formed is hard to change. Given 20 trials with conditions as at first in order to establish habit again. 1-10 9 1 8 2 11-20 10 0 9 1 Colors reversed, no other change. To test influence of colors. 1-10 6 4 10 0 INFLUENCE OF DISTURBANCE WHEN ANIMAL IS ENTERING BOX. No Disturbance. Animal Touched. To Red (Right). To White (Left). To Red. To White. 2 8 5 5 This was after the tendency to go to the Left at the entrance had been established. These experiments to test the effect of changing colors are also of interest in that they show in a remarkable way the influence of the direction of turning. The animal after succeeding in getting around the first part of the labyrinth failed entirely to escape at the exit. Here it should have turned to the left, instead of the right as it was accustomed to, but it persisted in turning to the right. Fig. 3 represents approximately the path taken in the first trial; it shows the way in which the animal persisted in trying to get out on the right. From this it is clear that both vision and the complex sensations of turning are important. [Illustration: FIG. 3. Labyrinth with Conditions the Reverse of the Usual. (Compare with FIG. 2.) The colors as well as the partitions have been shifted. The path is, approximately, that taken by No. 2 in the first trial after the reversal of conditions.] The latter part of Table IV. presents further evidence in favor of vision. For these tests the colors alone were reversed. Previous to the change the animal had been making no mistakes whatever, thereafter there were four mistakes at the entrance and none at the exit. Later, another experiment under the same conditions was made with the same animal, No. 2, with still more pronounced results. In this case the animal went to the white, that is, in this instance, into the blind alley, and failed to get out; several times it jumped over to the left side (the open-passage side) of the box but each time it seemed to be attracted back to the white or repelled by the red, more probably the latter, as the animal had been trained for weeks to avoid the red. Concerning the delicacy of visual discrimination I hope to have something to present in a later paper. The tactual stimuli given by contact with the series of wires used for the electrical stimulus also served to guide the frogs. They were accustomed to receive an electrical shock whenever they touched the wires on the blocked side of the entrance, hence on this side the tactual stimulus was the signal for a painful electrical stimulus. When the animal chose the open passage it received the tactual stimulus just the same, but no shock followed. After a few days' experimentation it was noted that No. 2 frequently stopped as soon as it touched the wires, whether on the open or the closed side. If on the closed side, it would usually turn almost immediately and by retracing its path escape by the open passage; if on the open side, it would sometimes turn about, but instead of going back over the course it had just taken, as on the other side, it would sit still for a few seconds, as if taking in the surroundings, then turn again and go on its way to the exit. This whole reaction pointed to the formation of an association between the peculiar tactual sensation and the painful shock which frequently followed it. Whenever the tactual stimulus came it was sufficient to check the animal in its course until other sensory data determined the next move. When the wrong passage had been chosen the visual data gotten from the appearance of the partition which blocked the path and other characteristics of this side of the labyrinth determined that the organism should respond by turning back. When, on the other hand, the open passage had been selected, a moment's halt sufficed to give sensory data which determined the continuation of the forward movement. Although this reaction did not occur in more than one tenth of the trials, it was so definite in its phases as to warrant the statements here made. Fig. 4 gives the path taken by No. 2 in its 123d trial. In this experiment both choices were correctly made, but when the frog touched the wires on the open side it stopped short and wheeled around; after a moment it turned toward the exit again, but only to reverse its position a second time. Soon it turned to the exit again, and this time started forward, taking a direct course to the tank. The usual course for animals which had thoroughly learned the way to the tank is that chosen in Fig. 5. [Illustration: FIG. 4. Path of No. 2 for 123d Trial. Showing the response to the tactual stimulus from wires.] An interesting instance of the repetition of a reaction occurred in these experiments. A frog would sometimes, when it was first placed in the box, by a strong jump get up to the edge; it seldom jumped over, but instead caught hold of the edge and balanced itself there until exhaustion caused it to fall or until it was taken away. Why an animal should repeat an action of the nature of this is not clear, but almost invariably the second trial resulted in the same kind of reaction. The animal would stop at the same point in the box at which it had previously jumped, and if it did not jump, it would look up as if preparing to do so. Even after a frog had learned the way to the tank such an action as this would now and then occur, and almost always there would follow repetition in the manner described. [Illustration: FIG. 5. Path Usually Taken by Animal Having Perfectly-formed Habit.] 4. _The Effect of Fear upon Habit Formation._--A certain amount of excitement undoubtedly promotes the formation of associations, but when the animal is frightened the opposite is true. I have no hesitation in stating that, in case of the green frog, any strong disturbing stimulus retards the formation of associations. Although the frogs gave little evidence of fear by movements after being kept in the laboratory for a few weeks, they were really very timid, and the presence of any strange object influenced all their reactions. Quiescence, it is to be remembered, is as frequently a sign of fear as is movement, and one is never safe in saying that the frog is not disturbed just because it does not jump. The influence of the experimenter's presence in the room with the frogs which were being tried in the labyrinth became apparent when the animals were tried in a room by themselves. They escaped much more quickly when alone. In order to keep records of the experiments it was necessary for me to be in the room, but by keeping perfectly quiet it was possible to do this without in any objectionable way influencing the results. It may be, however, that for this reason the learning is somewhat slower than it would have been under perfectly natural conditions. Early in this paper reference was made to the fact that the frog did not learn to escape from a box with a small opening at some distance from the floor if it was prodded with a stick. I do not mean to say that the animal would never learn under such conditions, but that they are unfavorable for the association of stimuli and retard the process. This conclusion is supported by some experiments whose results are tabulated at the bottom of Table IV. In these trials the animal had been trained to go to the left and to avoid red. At first ten trials were given in which the frog was in no way disturbed. The result was eight right choices and two wrong ones. For the next ten trials the frog was touched with a stick and thus made to enter the labyrinth from the box, _A_. This gave five right and five wrong choices, apparently indicating that the stimulus interfered with the choice of direction. Several other observations of this nature point to the same conclusion, and it may therefore be said that fright serves to confuse the frog and to prevent it from responding to the stimuli which would ordinarily determine its reaction. 5. _The Permanency of Associations._--After the labyrinth habit had been perfectly formed by No. 2, tests for permanency were made, (1) after six days' rest and (2) after thirty days. Table V. contains the results of these tests. They show that for at least a month the associations persist. And although there are several mistakes in the first trials after the intervals of rest, the habit is soon perfected again. After the thirty-day interval there were forty per cent. of mistakes at the exit for the first series, and only 20 per cent. at the entrance. This in all probability is explicable by the fact that the colors acted as aids at the entrance, whereas at the exit there was no such important associational material. TABLE V. PERMANENCY OF ASSOCIATIONS. FROG NO. 2. Tests after six days' rest (following the results tabulated in Table III.). Trial. Entrance. Exit. Right. Wrong. Right. Wrong 1-10 7 3 8 2 (110-120) 11-20 10 0 10 0 Tests after THIRTY days' rest. 1-10 8 2 6 4 10-20 10 0 10 0 D. Association of Stimuli.--In connection with reaction-time work an attempt was made to form an association between a strong visual stimulus and a painful electrical shock, with negative results. A reaction box, having a series of interrupted circuits in the bottom like those already described for other experiments, and an opening on one side through which a light could be flashed upon the animal, served for the experiments. The tests consisted in the placing of a frog on the wires and then flashing an electric light upon it: if it did not respond to the light by jumping off the wires, an electrical stimulus was immediately given. I have arranged in Table VI. the results of several weeks' work by this method. In no case is there clear evidence of an association; one or two of the frogs reacted to the light occasionally, but not often enough to indicate anything more than chance responses. At one time it looked as if the reactions became shorter with the continuation of the experiment, and it was thought that this might be an indication of the beginning of an association. Careful attention to this aspect of the results failed to furnish any satisfactory proof of such a change, however, and although in the table statements are given concerning the relative numbers of short and long reactions I do not think they are significant. TABLE VI. ASSOCIATION OF ELECTRICAL AND VISUAL STIMULI. FROG No. 1a, 2a, 3a, 4a, 5a, A and Z. Frog. Total No. Days. Result. Trials. No. 1a 180 18 Increase in number of long reaction toward end. No evidence of association. No. 2a 180 17 Increase in number of short reactions toward end. No evidence of association. No. 3a 180 17 Marked increase in the number of short reactions toward end. No other evidence of association. No. 4a 200 19 Slight increase in the short reactions. There were a few responses to the light on the third day. No. 5a 200 20 No increase in the number of short reactions. Few possible responses to light on second and third days. Frog A 250 20 No evidence of association. Frog Z 450 28 No evidence of association. To all appearances this is the same kind of an association that was formed, in the case of the labyrinth experiments, between the tactual and the electrical stimuli. Why it should not have been formed in this case is uncertain, but it seems not improbable that the light was too strong an excitement and thus inhibited action. There is also the probability that the frog was constrained by being placed in a small box and having the experimenter near. III. SUMMARY. 1. The green frog is very timid and does not respond normally to most stimuli when in the presence of any strange object. Fright tends to inhibit movement. 2. That it is able to profit by experience has been proved by testing it in simple labyrinths. A few experiences suffice for the formation of simple associations; but in case of a series of associations from fifty to a hundred experiences are needed for the formation of a perfect habit. 3. Experiment shows that the frog is able to associate two kinds of stimuli, _e.g._, the peculiar tactual stimulus given by a wire and a painful electric stimulus which in the experiments followed the tactual. In this case the animal learns to jump away, upon receiving the tactual stimulus, before the experimenter gives the electric stimulus. 4. Vision, touch and the organic sensations (dependent upon direction of turning) are the chief sensory factors in the associations. The animals discriminate colors to some extent. 5. Perfectly formed habits are hard to change. 6. Fear interferes with the formation of associations. 7. Associations persist for at least a month. PART II. REACTION TIME OF THE GREEN FROG TO ELECTRICAL AND TACTUAL STIMULI. IV. THE PROBLEMS AND POSSIBILITIES OF COMPARATIVE REACTION-TIME STUDIES. Animal reaction time is at present a new field of research of evident importance and full of promise. A great deal of time and energy has been devoted to the investigation of various aspects of the time relations of human neural processes; a multitude of interesting facts have been discovered and a few laws established, but the results seem disproportionate to the amount of patient labor expended. Physiologists have determined the rate of transmission of the neural impulse for a few animals, and rough estimates of the time required for certain changes in the nervous system have been made, but this is all we have to represent comparative study. Just the path of approach which would seem most direct, in case of the time of neural changes, has been avoided. Something is known of the ontogenetic aspect of the subject, practically nothing of the phylogenetic; yet, in the study of function the comparative point of view is certainly as important as it is in the study of structure. In calling attention to the importance of the study of animal reaction time I would not detract from or minimize the significance of human investigations. They are all of value, but they need to be supplemented by comparative studies. It is almost impossible to take up a discussion of the time relations of neural processes without having to read of physiological and psychological time. The time of nerve transmission, we are told, is pure physiological time and has nothing whatever to do with psychic processes; the time occupied by the changes in brain centers is, on the contrary, psychological time. At the very beginning of my discussion of this subject I wish to have it clearly understood that I make no such distinction. If one phase of the neural process be called physiological time, with as good reason may all be so named. I prefer, therefore, to speak of the time relations of the neural process. Of the value of reaction-time studies, one may well believe that it lies chiefly in the way of approach which they open to the understanding of the biological significance of the nervous system. Certainly they are not important as giving us knowledge of the time of perception, cognition, or association, except in so far as we discover the relations of these various processes and the conditions under which they occur most satisfactorily. To determine how this or that factor in the environment influences the activities of the nervous system, and in what way system may be adjusted to system or part-process to whole, is the task of the reaction-time investigator. The problems of reaction time naturally fall within three classes: Those which deal with (1) nerve transmission rates; (2) the time relations of the spinal center activities, and (3) brain processes. Within each of these groups there are innumerable special problems for the comparative physiologist or psychologist. Under class 1, for instance, there is the determining of the rates of impulse transmission in the sensory and the motor nerves, (_a_) for a variety of stimuli, (_b_) for different strengths of each stimulus, (_c_) for different conditions of temperature, moisture, nourishment, fatigue, etc., in case of each stimulus, (_d_) and all this for hundreds of representative animals. From this it is clear that lines of work are not lacking. Closely related to these problems of rate of transmission are certain fundamental problems concerning the nature of the nerve impulse or wave. Whether there is a nerve wave, the reaction-time worker has as favorable an opportunity to determine as anyone, and we have a right to expect him to do something along this line. The relations of the form of the nerve impulse to the rhythm of vital action, to fatigue and to inhibition are awaiting investigation. Some of the most important unsettled points of psychology depend upon those aspects of neural activities which we ordinarily refer to as phenomena of inhibition, and which the psychologist is helpless to explain so long as the physiological basis and conditions are not known. Then, too, in the study of animals the relation of reaction time to instincts, habits, and the surroundings of the subject are to be noted. Variability and adaptability offer chances for extended biological inquiries; and it is from just such investigations as these that biology has reason to expect much. The development of activity, the relation of reflex action to instinctive, of impulsive to volitional, and the value of all to the organism, should be made clear by reaction-time study. Such are a few of the broad lines of inquiry which are before the comparative student of animal reaction time. It is useless to dwell upon the possibilities and difficulties of the work, they will be recognized by all who are familiar with the results of human studies. In the study of the time relations of neural processes Helmholtz was the pioneer. By him, in 1850, the rate of transmission of the nerve impulse in the sciatic nerve of the frog was found to be about 27 meters per second[4]. Later Exner[5] studied the time occupied by various processes in the nervous system of the frog by stimulating the exposed brain in different regions and noting the time which intervened before a contraction of the gastrocnemius in each case. Further investigation of the frog's reflex reaction time has been made by Wundt[6], Krawzoff and Langendorff[7], Wilson[8] and others, but in no case has the method of study been that of the psychologist. Most of the work has been done by physiologists who relied upon vivisectional methods. The general physiology of the nervous system of the frog has been very thoroughly worked up and the papers of Sanders-Ezn[9], Goltz[10] Steiner[11] Schrader[12] and Merzbacher[13],[14] furnish an excellent basis for the interpretation of the results of the reaction-time studies. [4] Helmholtz, H.: 'Vorläufiger Bericht über die Portpflanzungsgeschwindigkeit der Nervenreizung.' _Arch. f. Anal. u. Physiol._, 1850, S. 71-73. [5] Exner, S.: 'Experimentelle Untersuchung der einfachsten psychischen Processe.' _Pflüger's Arch._, Bd. 8. 1874, S. 526-537. [6] Wundt, W.: 'Untersuchungen zur Mechanik der Nerven und Nervencentren.' Stuttgart, 1876. [7] Krawzoff, L., und Langendorff, O.: 'Zur elektrischen Reizung des Froschgehirns.' _Arch. f. Anal. u. Physiol._, Physiol. Abth., 1879, S. 90-94. [8] Wilson, W.H.: 'Note on the Time Relations of Stimulation of the Optic Lobes of the Frog.'_Jour. of Physiol._, Vol. XI., 1890, pp. 504-508. [9] Sanders-Ezn: 'Vorarbeit für die Erforschung des Reflexmechanismus in Lendentmark des Frosches.' _Berichte über die Verhandlungen der Kgl. sächs. Gesellsch. d. Wissensch. zu Leipzig_, 1867, S. 3. [10] Goltz, F.: 'Beiträge zur Lehre von den Functionen der Nervencentren des Frosches.' Berlin, 1869, 130 S. [11] Steiner, J.: 'Untersuchungen über die Physiologie des Froschhirns.' Braunschweig, 1885, 127 S. [12] Schrader, M.G.: 'Zur Physiologie des Froschgehirns.' _Pflüger's Arch._, Bd. 41, 1887, S. 75-90. [13] Merzbacher, L.: 'Ueber die Beziebungen der Sinnesorgane zu den Reflexbewegungen des Frosches.' _Pflüger's Arch._, Bd. 81, 1900, S. 223-262. [14] Merzbacher, L.: 'Untersuchungen über die Regulation der Bewegungen der Wirbelthiere. I. Beobachtungen an Fröschen.' _Pflüger's Arch._, Bd. 88, 1901, S. 453-474, 11 Text-figuren. In the present investigation it has been my purpose to study the reactions of the normal frog by the reaction-time methods of the psychologist. Hitherto the amount of work done, the extent of movements or some other change has been taken as a measure of the influence of a stimulus. My problem is, What are the time relations of all these reactions? With this problem in mind I enter upon the following program: (1) Determination of reaction time to electrical stimuli: (_a_) qualitative, (_b_) quantitative, (_c_) for different strengths of current; (2) Determination of reaction time to tactual stimuli (with the same variations); (3) Auditory: (_a_) qualitative, (_b_) quantitative, with studies on the sense of hearing; (4) Visual: (_a_) qualitative, (_b_) quantitative, with observations concerning the importance of this sense in the life of the frog, and (5) Olfactory: (_a_) qualitative, (_b_) quantitative. The present paper presents in rather bare form the results thus far obtained on electrical, tactual, and auditory reaction time; discussion of them will be deferred until a comparison of the results for the five kinds of stimuli can be given. V. METHOD OF STUDY. The measurements of reaction time herein considered were made with the Hipp Chronoscope. Cattell's 'Falling Screen' or 'Gravity Chronoscope' was used as a control for the Hipp. The Gravity Chronoscope consists of a heavy metal plate which slides easily between two vertical posts, with electrical connections so arranged that the plate, when released from the magnet at the top of the apparatus, in its fall, at a certain point breaks an electric circuit and at another point further down makes the same circuit. The rate of fall of the plate is so nearly constant that this instrument furnishes an accurate standard time with which Hipp readings may be compared, and in accordance with which the Hipp may be regulated. For, since the rate of a chronoscope varies with the strength of the current in use, with the variations in temperature and with the positions of the springs on the magnetic bar, it is always necessary to have some standard for corrections. In these experiments the time of fall of the gravity chronoscope plate, as determined by the graphic method with a 500 S.V. electric tuning fork, was 125[sigma] (_i.e._, thousandths of a second). This period, 125[sigma], was taken as a standard, and each hour, before the beginning of reaction-time experiments, the time of the plate's fall was measured ten times with the Hipp, and for any variation of the average thus obtained from 125[sigma], the standard, the necessary corrections were made by changing the position of the chronoscope springs or the strength of the current. The standard of comparison, 125[sigma], is shorter than most of the reaction times recorded, but since the time measured was always that from the breaking to the making of the circuit passing through the chronoscope it cannot be urged that there were errors resulting from the difference of magnetization which was caused by variations in the reaction time. But it is evident that the danger from differences in magnetization, if such exists, is not avoided in this way; instead, it is transferred from the reaction time proper to the period of preparation immediately preceding the reaction; for, from the moment the chronoscope is started until the stimulus is given a current is necessarily passing through the instrument. At a verbal signal from the operator the assistant started the chronoscope; the stimulus was then given by the operator, and the instrument recorded the time from the breaking of the circuit, effected by the stimulating apparatus, to the making of the circuit by the reaction of the animal. Despite precautions to prevent it, the period from the starting of the chronoscope to the giving of the stimulus was variable, and errors were anticipated, but a number of the tests proved that variations of even a second did not cause any considerable error. A fairly constant current for the chronoscope was supplied by a six-cell 'gravity battery' in connection with two storage cells, _GB_ (Fig. 6). This current could be used for two hours at a time without any objectionable diminution in its strength. The introduction of resistance by means of the rheostat, _R_, was frequently a convenient method of correcting the chronoscope. [Illustration: FIG. 6. General Plan of Apparatus in Diagram. _H_, Hipp Chronoscope; _R_, rheostat; _C_, commutator; _SC_, storage cells; _GB_, 'Excello' gravity battery; _F_, Cattell's falling screen; _T_, reaction table; _RK_, reaction key; _SK_, Stimulating apparatus; _K_, key in chronoscope circuit; _S_, stimulus circuit.] Fig. 6 represents the general plan of the apparatus used in these experiments. The general method of experimentation is in outline as follows: 1. At a 'ready' signal from the operator the assistant makes the chronoscope circuit by closing a key, _K_ (Fig. 6), and then immediately starts the chronoscope. 2. Stimulus is given by the operator as soon as the chronoscope is started, and by this act the chronoscope circuit is broken and the record begun. 3. Animal reacts and by its movements turns a key, _RK_ (Fig. 6), thus making the chronoscope circuit and stopping the record. 4. Assistant stops chronoscope and takes reading. [Illustration: FIG. 7. Reaction Key. _l_, lever swung on pivot; _p, p_, posts for contacts with platinum plates on base; _b_, upright bar for string; _s_, spring for clamping string; _w_, wheel to carry string; _c, c_, chronoscope circuit; 1 and 2, points which are brought into contact by animal's reaction.] The steps of this process and the parts of the apparatus concerned in each may be clearly conceived by reference to the diagram given in Fig. 6. The various forms of stimulating apparatus used and the modification of the method will be described in the sections dealing with results. The same reaction key was used throughout (see Fig. 7). Its essential features are a lever _l_, pivoted in the middle and bearing a post at either end, _p, p_. From the middle of this lever there projected upward a small metal bar, _b_, through the upper part of which a string to the animal ran freely except when it was clamped by the spring, _s_. This string, which was attached to the subject's leg by means of a light elastic band, after passing through the bar ran over a wheel, _w_, and hung tense by reason of a five-gram weight attached to the end. Until everything was in readiness for an experiment the string was left free to move through the bar so that movement of the animal was not hindered, but the instant before the ready-signal was given it was clamped by pressure on _s_. The diagram shows the apparatus arranged for a reaction. The current is broken, since 1 and 2 are not in contact, but a slight movement of the animal turns the lever enough to bring 1 against 2, thus making the circuit and stopping the chronoscope. When the motor reaction of the subject was violent the string pulled out of the clamp so that the animal was free from resistance, except such as the string and weight offered. The five-gram weight served to give a constant tension and thus avoided the danger of error from this source. Between experiments the weight was placed on the table in order that there might be no strain upon the subject. That the subject might be brought into a favorable position for an experiment without being touched by the operator a special reaction box was devised. The animals used in these studies were specimens of _Rana clamitans_ which were kept in a tank in the laboratory throughout the year. VI. ELECTRIC REACTION TIME. The reaction time to electrical stimuli was determined first because it seemed probable that this form of the pain reaction would be most useful for comparison with the auditory, visual, olfactory and tactual reactions. In this paper only the electrical and the tactual reaction times will be considered. The former will be divided into two groups: (1) Those resulting from a stimulus given by touching electrodes to the leg of the frog, and (2) those gotten by having the frog resting upon wires through which a current could be passed at any time. _Group 1 of the electrical reactions_ were taken under the following conditions. A reaction box about 40 cm. in diameter was used. The mean temperature of the experimenting room was about 20° C. In all cases the string was attached to the left hind leg of the frog, and the stimulus applied to the middle of the gastrocnemius muscle of the right hind leg. Reaction times were taken in series of ten, excluding those which were imperfect. As the moistness of the skin affects the strength of the electric stimulus received, it was necessary to moisten the animal occasionally, but as it did not seem advisable to disturb it after each experiment this was done at intervals of five minutes throughout the series. Were it not for this precaution it might be said that lengthening of the reaction times toward the end of a series simply indicated the weakening of the stimulus which resulted from the gradual drying of the skin. The stimulus in this group was applied by means of the stimulating apparatus of Fig. 6. It is merely two wire electrodes which could be placed upon the animal, with the additional device of a key for the breaking of the chronoscope circuit the instant the stimulus was given. The most serious objection to this method of stimulating is that there is a tactual as well as an electrical stimulus. Before presenting averages, two representative series of reactions may be considered. SERIES I. FROG B. APRIL 9, 1900. 10 A.M. Temperature 19° C. String to left hind leg. Stimulus to right hind leg. Strength of stimulating current 1.0 volt, .0001 ampère. Number of Experiment. Hour. Reaction Time. Remarks. 1 10.25 No reaction. 2 10.27 No reaction. 3 10.30 139[sigma] 4 10.34 164 5 10.35 102 6 10.37 169 7 10.39 151 8 10.40 152 9 10.42 144 10 10.43 152 11 10.45 122 12 10.51 179 13 10.54 No reaction. Average of 10, 147.4[sigma] SERIES 2. FROG F. ELECTRICAL STIMULUS. No. Hour. Reaction Time. Remarks. Deviation from Mean. 1 10.19 35[sigma] Probable reaction to visual stim. 2 10.22 173 4.7 3 10.24 161 - 7.3 4 10.25 133 -35.3 5 10.26 199 30.7 6 10.28 130 -38.3 7 10.32 179 10.7 8 10.34 187 18.7 9 10.35 60 Probable reflex. 10 10.37 183 14.7 11 10.38 166 - 2.3 12 10.39 172 3.7 Average of 10, 168.3[sigma] Average of first 5, 159.2[sigma] Average Variation, 16.64[sigma] Average of second 5, 177.4[sigma] Both are fairly representative series. They show the extremely large variations, in the case of series 1, from 102 to 179[sigma]. In all these experiments such variation is unavoidable because it is impossible to have the conditions uniform. A very slight difference in the frog's position, which could not be detected by the operator, might cause considerable difference in the time recorded. Efforts were made to get uniform conditions, but the results seem to show that there is still much to be desired in this direction. Tables VII. contains the results of four series of ten reactions each for frog _A_. It will be noticed that the time for the first five in each series is much shorter than that for the last five; this is probably indicative of fatigue. TABLE VII. REACTION TIME OF FROG _A_ TO ELECTRICAL STIMULI. Series of Averages Averages of Averages of ten reactions. of series. first five. second five. 1 163.1[sigma] 134.6[sigma] 191.6[sigma] 2 186.2 176.2 196.2 3 161.1 125.2 197.0 4 158.3 101.6 215.0 General averages 167.2[sigma] 134.4[sigma] 199.9[sigma] TABLE VIII. REACTION TIME OF FROG _B_ TO ELECTRICAL STIMULI. 1 132.7[sigma] 118.2[sigma] 147.4[sigma] 2 196.6 167.8 225.4 3 147.4 145.5 149.8 4 157.5 152.0 163.0 General averages 158.6[sigma] 145.9[sigma] 171.4[sigma] TABLE IX. NORMAL AND REFLEX REACTION TIME OF SIX ANIMALS TO ELECTRICAL STIMULUS. Normal. Reflex. Average for 20 Average for 20 Frog. reactions. Mean Var. reactions. Mean Var. _A_ 149.5[sigma] 24.0[sigma] _B_ 158.3 16.0 51.5[sigma] 8.0[sigma] _C_ 191.0 24.3 _D_ 167.0 10.1 _E_ 182.4 28.0 45.1 5.5 _F_ 176.3 10.2 46.0 4.5 General Average. 167.9[sigma] 18.8[sigma] 47.5[sigma] 6.0[sigma] For _D_ the average is for ten reactions. _B_ and _E_ were males, _F_ a female; the sex of the others was not determined by dissection and is uncertain. Early in the experiments it became evident that there were three clearly defined types of reactions: there were a number of reactions whose time was shorter than that of the ordinary quick voluntary pain reaction, and there were also many whose time was considerably longer. The first type it was thought might represent the spinal reflex reaction time. For the purpose of determining whether the supposition was true, at the end of the series of experiments three of the frogs were killed and their reflex reaction time noted. This was done by cutting the spinal cord just back of the medulla, placing the animal on an experimenting board close to the reaction key with the thread from the key fastened to the left leg as in case of the previous work and stimulating the gastrocnemius with an induced current by the application of wire electrodes. In Table IX. the reflex reaction times for the three animals are given. The following results obtained with frog _E_ show that the time of reaction increases with the increase in the time after death. The average of 20 reactions by _E_ taken an hour after the cord had been cut was 45.5[sigma]; the average of 20 taken twenty hours later was 55.85[sigma]. As a rule the reflex reactions were but slightly variable in time as is indicated by the accompanying series. SERIES OF REFLEX REACTIONS OF FROG _F_. Taken at rate of one per minute. 1 50[sigma] 2 58 3 55 4 59 5 48 6 46 7 45 8 51 9 42 10 44 Throughout these experiments it was noticed that any stimulus might cause (1) a twitch in the limb stimulated, or (2) a twitch followed by a jump, or (3) a sudden jump previous to which no twitch could be detected. And it soon appeared that these types of reaction, as it seems proper to call them, would have to be considered in any determination of the mean reaction time. As proof of the type theory there is given (Fig. 8) a graphic representation of 277 reactions to the electrical stimulus. [Illustration: FIG 8: Distribution of 277 reactions.] The column of figures at the left indicates the number of reactions at any point. Below the base line are the classes. For convenience of plotting the reactions have been grouped into classes which are separated by 25[sigma]. Class 1 includes all reactions between 1[sigma] and 25[sigma], class 2 all from 25[sigma] to 50[sigma], and so on to 400[sigma], thereafter the classes are separated by 100[sigma]. It is noticeable that there is one well-marked mode at 75[sigma]. A second mode occurs at 175[sigma]. This is the primary and in our present work the chiefly significant mode, since it is that of the quick instinctive reaction to a stimulus. At 500[sigma] there is a third mode; but as such this has little meaning, since the reactions are usually pretty evenly distributed from 300[sigma] on to 2000[sigma]; if there is any grouping, however, it appears to be about 500[sigma] and 800[sigma]. The first mode has already been called the reflex mode. The short reactions referred to usually lie between 40[sigma] and 80[sigma], and since experiment has shown conclusively that the spinal reflex occupies about 50[sigma], there can be little doubt that the first mode is that of the reflex reaction time. The second mode represents those reactions which are the result of central activity and control. I should be inclined to argue that they are what we usually call the instinctive and impulsive actions. And the remaining reactions represent such as are either purely voluntary, if any frog action can be so described, or, in other words, depend upon such a balancing of forces in the brain as leads to delay and gives the appearance of deliberate choice. Everything points to some such classification of the types as follows: (1) Stimuli strong enough to be injurious cause the shortest possible reaction by calling the spinal centers into action, or if not spinal centers some other reflex centers; (2) slightly weaker stimuli are not sufficient to affect the reflex mechanism, but their impulse passes on to the brain and quickly discharges the primary center. There is no hesitation, but an immediate and only slightly variable reaction; just the kind that is described as instinctive. As would be expected, the majority of the frog's responses are either of the reflex or of this instinctive type. (3) There is that strength of stimulus which is not sufficient to discharge the primary center, but may pass to centers of higher tension and thus cause a response. This increase in the complexity of the process means a slower reaction, and it is such we call a deliberate response. Precisely this kind of change in neural action and in reaction time is at the basis of voluntary action. And (4) finally, the stimulus may be so weak that it will not induce a reaction except by repetition. Just above this point lies the threshold of sensibility, the determination of which is of considerable interest and importance. _Group 2 of the electrical reactions_ consists of three series taken to determine the relation of strength of stimulus to reaction time. The conditions of experimentation differed from those for group 1 in the following points: (1) The stimulus was applied directly by the making of a circuit through wires upon which the subject rested (Fig. 9); (2) the thread was attached to the right hind leg; (3) the thread, instead of being kept at the tension given by the 5-gram weight as in the former reactions, was slackened by pushing the upright lever of the reaction key one eighth of an inch toward the animal. This was done in order to avoid the records given by the slight twitches of the legs which precede the motor reaction proper. For this reason the reactions of group 2 are not directly comparable with those of group 1. Fig. 9 is the plan of the bottom of a reaction box 15 cm. at one end, 30 cm. at the other, 60 cm. long and 45 cm. deep. On the bottom of this, at one end, a series of interrupted circuits were arranged as shown in the figure. The wires were 1.2 cm. apart, and an animal sitting anywhere on the series necessarily touched two or more, so that when the stimulus key, X, was closed the circuit was completed by the animal's body; hence, a stimulus resulted. The stimulus key, X, was a simple device by which the chronoscope circuit, _c_, _c_, was broken at the instant the stimulus circuit, _s_, _c_, was made. Cells of 'The 1900 Dry Battery' furnished the current used as a stimulus. Three different strengths of stimulus whose relative values were 1, 2 and 4, were employed in the series 1, 2 and 3. Careful measurement by means of one of Weston's direct-reading voltmeters gave the following values: 1 cell, 0.2 to 0.5 volt, 0.00001 to 0.00003 ampère. This was used as the stimulus for series 1. 2 cells, 0.5 to 1.0 volt, 0.00003 to 0.00006 ampère. This was used for series 2. 4 cells, 1.2 to 1.8 volt, 0.00007 to 0.0001 ampère. This was used for series 3. [Illustration: Fig. 9. Ground Plan of Reaction Box for Electrical Stimuli (Group 2). _IC_, interrupted circuits; _CC_, chronoscope circuit; _X_, key for making stimulus circuit and breaking chronoscope circuit; _B_, stimulus battery; _S_, string from reaction key to animal. Scale 1/2.] The reactions now under consideration were taken in sets of 24 in order to furnish evidence on the problem of fatigue. The stimulus was given at intervals of one minute, and the subject was moistened at intervals of ten minutes. To obtain 24 satisfactory reactions it was usually necessary to give from thirty to forty stimulations. Five animals, numbers 1, 2, 4, 5, and 6, served as subjects. They were green frogs whose size and sex were as follows: Length. Weight. Sex. Number 1 7.5 cm. 35 grams. Male. Number 2 7.3 " 37 " Male. Number 4 8.2 " 50.4 " Female? Number 5 7.1 " 25 " Female. Number 6 7.8 " 42 " Male. For most of these frogs a one-cell stimulus was near the threshold, and consequently the reaction time is extremely variable. In Table X. an analysis of the reactions according to the number of repetitions of the stimulus requisite for a motor reaction has been made. Numbers 1 and 5 it will be noticed reacted most frequently to the first stimulus, and for them 48 satisfactory records were obtained; but in case of the others there were fewer responses to the first stimulus, and in the tabulation of series 1 (Table XI.) averages are given for less than the regular sets of 24 reactions each. TABLE X. ANALYSIS OF REACTIONS TO ONE-CELL STIMULUS. Frog. Reactions to To 2d. To 3d. To 4th. To 5th. More. Total No. first Stimulus. of Reactions. 1 53 2 1 0 0 1 57 2 20 12 5 5 4 12 58 4 31 15 1 0 2 8 57 5 51 11 1 2 0 1 66 6 45 15 6 3 1 5 75 Totals, 200 55 14 10 7 27 313 Table XI. is self-explanatory. In addition to the usual averages, there is given the average for each half of the sets, in order that the effect of fatigue may be noted. In general, for this series, the second half is in its average about one third longer than the first half. There is, therefore, marked evidence of tiring. The mean reaction time for this strength of stimulus is difficult to determine because of the extremely great variations. At one time a subject may react immediately, with a time of not over a fifth of a second, and at another it may hesitate for as much as a second or two before reacting, thus giving a time of unusual length. Just how many and which of these delayed responses should be included in a series for the obtaining of the mean reaction time to this particular stimulus is an extremely troublesome question. It is evident that the mode should be considered in this case rather than the mean, or at least that the mean should be gotten by reference to the mode. For example, although the reaction times for the one-cell stimulus vary all the way from 150[sigma] to 1000[sigma] or more, the great majority of them lie between 200[sigma] and 400[sigma]. The question is, how much deviation from the mode should be allowed? Frequently the inclusion of a single long reaction will lengthen the mean by 10[sigma] or even 20[sigma]. What is meant by the modal condition and the deviation therefrom is illustrated by the accompanying curve of a series of reaction times for the electric stimulus of group I. __________________________________________________________________________ _8_|______________________________________________________________________ _7_|_____________________________________|________________________________ _6_|_____________________________________|________________________________ _5_|_____________________________________|________________________________ _4_|________________________________|____|____|___________________________ _3_|____________|___________________|____|____|___________________________ _2_|_______|____|____|_________|____|____|____|____|______________________ _1_|__|____|____|____|_________|____|____|____|____|____|____|____|____|__ 100 110 120 130 140 150 160 170 180 190 200 210 220 230 The column of figures at the left indicates the number of reactions; that below the base line gives the reaction times in classes separated by 10[sigma]. Of thirty-one reactions, seven are here in the class 170[sigma]. This is the model class, and the mean gotten by taking the average of 31 reactions is 162[sigma]. If the mode had been taken to represent the usual reaction time in this case, there would have been no considerable error. But suppose now that in the series there had occurred a reaction of 800[sigma]. Should it have been used in the determination of the mean? If so, it would have made it almost 30[sigma] greater, thus removing it considerably from the mode. If not, on what grounds should it be discarded? The fact that widely varying results are gotten in any series of reactions, points, it would seem, not so much to the normal variability as to accidental differences in conditions; and the best explanation for isolated reactions available is that they are due to such disturbing factors as would decrease the strength of the stimulus or temporarily inhibit the response. During experimentation it was possible to detect many reactions which were unsatisfactory because of some defect in the method, but occasionally when everything appeared to be all right an exceptional result was gotten. There is the possibility of any or all such results being due to internal factors whose influence it should be one of the objects of reaction-time work to determine; but in view of the fact that there were very few of these questionable cases, and that in series I, for instance, the inclusion of two or three reactions which stood isolated by several tenths of a second from the mode would have given a mean so far from the modal condition that the results would not have been in any wise comparable with those of other series, those reactions which were entirely isolated from the mode and removed therefrom by 200[sigma] have been omitted. In series I alone was this needful, for in the other series there was comparatively little irregularity. The results of studies of the reaction time for the one-cell electric stimulus appear in Table XI. The first column of this table contains the average reaction time or mean for each subject. Nos. 2 and 4 appeared to be much less sensitive to the current than the others, and few responses to the first stimulus could be obtained. Their time is longer than that of the others, and their variability on the whole greater. Individual differences are very prominent in the studies thus far made on the frog. The one-cell stimulus is so near the threshold that it is no easy matter to get a mean which is significant. Could the conditions be as fully controlled as in human reaction time it would not be difficult, but in animal work that is impossible. No attempt has thus far been made to get the reaction time in case of summation effects except in occasional instances, and in so far as those are available they indicate no great difference between the normal threshold reaction and the summation reaction, but on this problem more work is planned. There are large mean variations in Table XI., as would be anticipated. Since the reactions were taken in sets of 24, the means of each set as well as that of the total are given, and also, in columns 4 and 5, the means of the first half and the last half of each set. A comparison of Tables XI., XII. and XIII. makes clear the differences in reaction time correlated with differences in the strength of an electric stimulus. For Table XI., series I, the relative value of the stimulus was I; for Table XII., series 2, it was 2, and for Table XIII., series 3, it was 4. Throughout the series from I to 3 there is a rapid decrease in the reaction time and in the variability of the same. The reaction time for stimulus I, the so-called threshold, is given as 300.9[sigma]; but of the three it is probably the least valuable, for reasons already mentioned. The mean of the second series, stimulus 2, is 231.5[sigma] while that of the third, stimulus 4, is only 103.1[sigma]. This great reduction in reaction time for the four-cell stimulus apparently shows the gradual transition from the deliberate motor reaction, which occurs only after complex and varied central neural activities, and the purely reflex reaction, which takes place as soon as the efferent impulse can cause changes in the spinal centers and be transmitted as an afferent impulse to the muscular system. TABLE XI. ELECTRICAL STIMULUS REACTION TIME. SERIES 1. Average Average of Average Average Mean Var Frog. of all. Mean Var. Sets. of 1st h. of 2d h. of Sets. 1 238.5* 33.3* 216.0* 205.6* 226.7* 33.2* 261.0 248.0 274.1 33.3 2 458.0 219.0 458.0 270.4 643.8 219.0 4 273.4 59.9 273.4 245.7 301.1 59.9 5 263.9 50.5 268.6 244.7 292.5 44.9 259.2 236.0 282.4 56.1 6 271.1 65.1 322.6 273.2 372.0 87.9 219.6 208.5 230.6 42.3 Gen Av. 300.9 85.5 300.9 244.8 356.8 85.5 Totals. For No. 1 the averages are for 2 sets of 24 reactions each, 48 " 2 " " one set of 12 " " 12 " 4 " " one set of 24 " " 24 " 5 " " two sets of 24 " " 48 " 6 " " two sets of 24 and 12 reactions, respectively, 36 *Transcriber's Note: All values in [sigma], 1/1000ths of a second. TABLE XII. ELECTRICAL STIMULUS REACTION TIME. SERIES 2. Average Average of Average Average Mean Var Frog. of all. Mean Var. Sets. of 1st h. of 2d h. of Sets. 1 227.3* 33.7* 229.4* 209.1* 249.6* 25.5* 225.2 207.3 243.0 42.1 2 240.1 30.9 239.0 222.3 255.1 29.0 241.3 220.2 262.4 32.8 4 270.3 56.5 298.5 285.3 311.4 62.8 242.2 206.0 278.4 50.2 198.5 26.2 195.0 197.5 193.0 33.5 202.0 195.2 209.0 18.8 6 224.4 24.4 221.6 209.7 233.7 23.6 227.2 213.5 241.0 25.1 Gen. Av. 231.5 34.3 231.0 216.6 246.6 34.3 For No. 5 the averages are for two sets of 18 each; for all the others there are 24 in each set. *Transcriber's Note: All values in [sigma], 1/1000ths of a second. TABLE XIII. ELECTRICAL STIMULUS REACTION TIME. SERIES 3. Average Average Average Average Mean Var. Frog. of all. Mean Var. of all. of 1st h. of 2d h. of Sets. 1 93.6* 13.5* 91.8* 93.2* 90.4* 13.5* 95.4 91.8 99.0 13.5 2 99.9 12.8 92.2 89.4 95.0 17.4 107.5 105.9 109.0 8.2 4 125.2 16.3 113.5 106.5 120.5 13.6 136.0 135.7 138.2 19.0 5 94.4 8.0 88.6 90.5 88.6 8.2 100.2 97.8 102.7 7.9 6 102.5 12.2 104.2 98.6 109.9 12.8 100.9 101.0 108.3 11.6 Gen. Avs. 103.1 12.5 103.1 101.0 105.9 12.5 For each animal there are two sets of 24 reactions each. *Transcriber's Note: All values in [sigma], 1/1000ths of a second. The spinal reflex for a decapitated frog, as results previously discussed show, is approximately 50[sigma]; and every time the four-cell stimulus is given this kind of a reaction results. There is a slight twitch of the legs, immediately after which the animal jumps. Now for all these series the thread was slackened by one eighth of an inch, but the reflex time was determined without this slack. Calculation of the lengthening of the reaction time due to the slack indicated it to be between 20 and 30[sigma], so if allowance be made in case of the reactions to the four-cell stimulus, the mean becomes about 70[sigma], or, in other words, nearly the same as the spinal reflex. The conclusion seems forced, therefore, that when a stimulus reaches a certain intensity it produces the cord response, while until that particular point is reached it calls forth central activities which result in much longer and more variable reaction times. It was said above that the series under consideration gave evidence of the gradual transition from the reflex to the volitional in reaction time. Is this true, or do we find that there are well-marked types, between which reactions are comparatively rare? Examination of the tables VII., VIII., IX., XI., XII. and XIII. will show that between 70[sigma] and 150[sigma] there is a break. (In tables XI., XII. and XIII., allowance must always be made for the slack in the thread, by subtracting 30[sigma].) All the evidence furnished on this problem by the electrical reaction-time studies is in favor of the type theory, and it appears fairly clear that there is a jump in the reaction time from the reflex time of 50-80[sigma], to 140 or 150[sigma], which may perhaps be taken as the typical instinctive reaction time. From 150[sigma] up there appears to be a gradual lengthening of the time as the strength of the stimulus is decreased, until finally the threshold is reached, and only by summation effect can a response be obtained. The most important averages for the three series have been arranged in Table XIV. for the comparison of the different subjects. Usually the reaction time for series 3 is about one half as long as that for series 2, and its variability is also not more than half as large. In the small variability of series 3 we have additional reason for thinking that it represents reflexes, for Table IX. gives the mean variation of the reflex as not more than 8[sigma], and the fact that the means of this series are in certain cases much larger is fully explained by the greater opportunity for variation afforded by the slack in the thread. TABLE XIV. MEANS, ETC., FOR EACH SUBJECT FOR THE THREE SERIES. (TIME IN [sigma]) Mean First Second Mean Frog. Half. Half. Variation. Series 1 238.5 226.8 259.4 33.3 Series 2 227.3 208.2 246.3 33.7 No. 1 Series 3 93.6 92.5 94.7 13.5 Series 1 458.0 270.4 643.8 219.0 Series 2 240.1 221.2 258.8 30.9 No. 2 Series 3 99.9 97.6 102.0 12.8 Series 1 273.4 245.7 301.1 59.9 Series 2 270.3 245.6 294.9 56.5 No. 4 Series 3 125.2 121.1 129.3 16.3 Series 1 263.9 240.4 287.4 50.5 Series 2 198.5 196.4 201.0 26.2 No. 5 Series 3 94.4 94.2 94.7 8.0 Series 1 271.1 240.8 301.3 65.1 Series 2 224.4 211.6 237.3 24.4 No. 6 Series 3 102.5 99.8 109.1 12.2 A striking fact is that the averages for the first and last half of sets of reactions differ more for the weak than for the strong stimulus. One would naturally expect, if the increase were a fatigue phenomenon purely, that it would be greatest for the strongest stimulus; but the results force us to look for some other conditions than fatigue. A stimulus that is sufficiently strong to be painful and injurious to an animal forces an immediate response so long as the muscular system is not exhausted; but where, as in series 1 and 2 of the electrical stimulus, the stimulus is not harmful, the reason for a sudden reaction is lacking unless fear enters as an additional cause. Just as long as an animal is fresh and unfamiliar with the stimulus there is a quick reaction to any stimulus above the threshold, and as soon as a few experiences have destroyed this freshness and taught the subject that there is no immediate danger the response becomes deliberate. In other words, there is a gradual transition from the flash-like instinctive reaction, which is of vast importance in the life of such an animal as the frog, to the volitional and summation responses. The threshold electrical stimulus does not force reactions; it is a request for action rather than a demand, and the subject, although startled at first, soon becomes accustomed to the experience and responds, if at all, in a very leisurely fashion. The reaction time to tactual stimuli, soon to be considered, was determined by giving a subject only three or four stimulations a day; if more were given the responses failed except on repetition or pressure; for this reason the data on fatigue, or lengthening of reaction time toward the end of a series, are wanting in touch. A few tests for the purpose of discovering whether the time would lengthen in a series were made with results very similar to those of the threshold electrical stimulus; the chief difference lies in the fact that the responses to touch fail altogether much sooner than do those to the electrical stimulus. This, however, is explicable on the ground that the latter is a stimulus to which the animal would not be likely to become accustomed so soon as to the tactual. First Half. Second Half. Second % Greater. Series 1 244.8[sigma] 356.8[sigma] 46 per cent Series 2 216.6 246.6 14 " Series 3 101.0 105.9 5 " If pure fatigue, that is, the exhaustion of the nervous or muscular system, appears anywhere in this work, it is doubtless in series 3, for there we have a stimulus which is so strong as to force response on penalty of death; the reaction is necessarily the shortest possible, and, as a matter of fact, the motor reaction (jump forward) here occupies little more time than the leg-jerk of a decapitated frog. This probably indicates that the reaction is a reflex, and that the slight increase in its length over that of the spinal reflex is due to occasional cerebellar origin; but of this there can be no certainly from the evidence herewith presented. At any rate, there is no possibility of a voluntary reaction to the strong current, and any changes in the general character of the reaction time in a series will have to be attributed to fatigue of the nervous or muscular systems. The second halves of the sets of series 3 are 5 per cent. longer than the first, and unless this is due to the partial exhaustion of the nervous system it is hard to find an explanation of the fact. Fatigue of the muscles concerned seems out of the question because the reactions occur at the rate of only one per minute, and during the rest interval any healthy and well-nourished muscle would so far recover from the effect of contraction that it would be able to continue the rhythmic action for long periods. To the inquiry, Does fatigue in the experiments mean tiring by the exhaustion of nerve energy, or is the lengthening in reaction time which would naturally be attributed to tiring due to the fact that experience has shown quick reaction to be unnecessary? we shall have to reply that there is evidence in favor of both as factors. There can be little doubt that in case of the strong stimuli there is genuine fatigue which makes quick reaction impossible; but at the same time it is certain that the 40 to 50 per cent. increase of the second half of sets in series 1 over the first half can not be due to fatigue, for the strain is here evidently much less than for series 3. Rather, it would seem that habituation instead of exhaustion is the all-important cause of the difference in series 1 and 2. It becomes clear from these considerations that the repetition of a stimulus can never mean the repetition of an effect. VII. TACTUAL REACTION TIME. In the following work on the reactions to tactual stimulation the subject was placed in a large reaction box with a thread attached to one of its legs and passing to a reaction key, as in the experiments already described. The box in which the subject was confined was surrounded by movable cloth curtains to prevent the animal's escape and at the same time permit the experimenter to work without being seen by the frog. Tactual stimulation was given by means of a hand key[15] similar to that used for electrical stimulation which is represented in Fig. 6. The touch key ended in a hard-rubber knob which could be brought in contact with the skin of the subject. This key was fixed to a handle of sufficient length to enable the operator to reach the animal wherever it chanced to be sitting in the reaction box. Stimulation was given by allowing the rubber point of the touch key to come in contact with the skin in the middle region of the subject's back. As soon as the point touched the animal the chronoscope circuit was broken by the raising of the upper arm of the key. [15] This apparatus was essentially the same as Scripture's device for the giving of tactual stimulation. As a precaution against reactions to visual stimuli, which it might well be supposed would appear since the subject could not in every case be prevented from seeing the approaching apparatus, the frog was always placed with its head away from the experimenter so that the eyes could not readily be directed toward the touch apparatus. Notwithstanding care in this matter, a reaction occasionally appeared which was evidently due to some disturbance preceding the tactual stimulus which served as a warning or preparation for the latter. All such responses were at once marked as questionable visual reactions and were not included in the series of touch reactions proper. As has been mentioned in connection with the discussion of fatigue, it was found absolutely necessary to have the subjects perfectly fresh and active, and for this purpose it was advisable to give not more than three or four stimulations at any one time. The subject was usually kept in the reaction box from 30 to 45 minutes, dependent upon the success of the experiments. As the work progressed it became evident that the responses to the stimulus were becoming less and less certain and slower, that the subjects were becoming accustomed to the novel experience and no longer suffered the surprise which had been the cause of the prompt reactions at first. It seemed best for this reason not to continue the work longer than two weeks, and as a consequence it was impossible to base the averages on more than twenty reactions for each subject. So far as the tension of the thread is concerned, the condition for the tactual reaction time was the same as that for the first group of electrical reaction-time experiments. In comparing the tactual with the electrical of series 1, 2 and 3, allowance must be made for the slack in the latter cases. Selection of the tactual reaction times upon which the mean is based, has been made with reference to the mode for each set of experiments. Inspection of the curves given by the reactions of each subject indicated that the great majority of the responses lay between 100 and 300[sigma], and that those which were beyond these limits were isolated and, in all probability, exceptional reactions due to some undetected variation in conditions which should throw them out of the regular series. On this account it was thought best to use only reactions between 100 and 300[sigma]. For convenience of comparison, again, the averages for the electrical reaction time of subjects _A_, _B_, _C_, _D_, _E_ and _F_, and the same for the tactual reaction time of subjects 1, 2, 3, 4, 5 and 6 are herewith given together. All averages are for twenty reactions, except for _D_ and 5, for which there are ten. Besides the usual determination for the tactual reaction-time work on the six subjects named, there is given in Table XVI. the electrical reaction time of these animals to a two-cell current. Comparison of the electrical and tactual results are of interest in this case because the mean variation for each is about 34[sigma], being 34.3[sigma], for the electrical and 33.8[sigma], for the tactual. TABLE XV. Average of 20 Electrical Average of 20 Tactual Frog. Reactions. Frog. Reactions. _A_ 149.5[sigma] 1 188.3[sigma] _B_ 158.3 2 199.1 _C_ 191.0 3 212.1 _D_ 167.0 4 213.0 _E_ 182.4 5 199.8 _F_ 176.3 6 221.9 Gen. Avs. 167.9 205.7 TABLE XVI. REACTION TIME FOR TACTUAL AND ELECTRICAL STIMULI. Tactual Reaction Time. Electrical Reaction Time. Frog. Average. Mean Variation. Average. Mean Variation. 1 188.3[sigma] 167.3[sigma] 2 199.1 180.1 3 212.1 4 213.0 210.3 5¹ 199.8 138.5 6 221.9 164.4 Gen. Avs. 205.7 33.8 172.1 34.3 ¹For 5 the average of ten instead of twenty is given. VIII. EQUAL VARIABILITY AS A CRITERION OF COMPARABILITY OF REACTION TIME FOR DIFFERENT KINDS OF STIMULI. Since variability as indicated in the study of the influence of different strengths of electrical stimulus becomes less as the stimulus increases, parity in variability for different stimuli offers a basis for the comparison of reaction times. Certain it is that there is no use in comparing the reaction times for different senses or different qualities of stimuli unless the relative values of the stimuli are taken into consideration; but how are these values to be determined unless some such index as variability is available? If the reaction time to tactual stimuli as here presented is to be studied in its relation to the electrical reaction time, it will mean little simply to say that the former is longer than the latter, because the electrical reaction time for a one-cell stimulus happens to be somewhat less than that for the particular tactual stimulus used. For it is clear that this tactual reaction time is really shorter than the reaction time to a weak current. In making variability a basis of comparison it must be assumed that the strength of stimulus is the important factor, and that all other variable conditions are, so far as possible, excluded. If, now, on the basis of parity in variability we compare the tactual and electrical reaction times, it is apparent that the tactual is considerably longer. The tactual average of Table XV. is 205.7[sigma], while the electrical reaction time which has approximately the same variability is 172.1[sigma]. It may well be objected that I have no right to make variability the basis of my comparison in these experiments, because the work for the various kinds of stimuli was done under different conditions. Admitting the force of this objection, and at the same time calling attention to the fact that I do not wish to lay any stress on the results of the comparisons here made, I take this opportunity to call attention to the possibility of this criterion. The use of variability as a basis of comparison would involve the assumptions (1) that a certain intensity of every stimulus which is to be considered is capable of producing the shortest possible, or reflex reaction, and that this reaction is at the same time the least variable; (2) that as the strength of a stimulus decreases the variability increases until the threshold is reached. Suppose, now, it is our desire to compare the results of reactions to different intensities of electrical and tactual stimuli; let the figures be as follows: Reaction Time. Variability. Stimulus Strength. Elect. Touch. Elect. Touch. 8 50[sigma] 50[sigma] 10[sigma] 10[sigma]. 4 130 155 25 30 2 175 220 40 40 1 300 320 50 60 In the double columns the results for electrical stimuli are given first, and in the second column are the tactual. Stimulus 8 is assumed to be of sufficient strength to induce what may be designated as forced movement, and whatever the quality of the stimulus this reaction time is constant. I make this statement theoretically, although all the evidence which this work furnishes is in support of it. So, likewise, is the variability of this type of reaction time small and nearly constant. At the other extreme, stimulus 1 is so weak as to be just sufficient to call forth a response; it is the so-called threshold stimulus. Whether all qualities of stimulus will give the same result here is a question to be settled by experimentation. Wundt contends that such is the case, but the observations I have made on the electrical and tactual reactions of the frog cause me to doubt this assumption. It seems probable that the 'just perceptible stimulus reaction time' is by no means the same thing for different qualities of stimulus. Those modifications of the vital processes which alone enable organisms to survive, make their appearance even in the response to the minimal stimulus. In one case the just perceptible stimulus may cause nothing more than slight local changes in circulation, excretion, muscular action; in another it may produce, just because of the particular significance of the stimulus to the life of the organism, a violent and sudden motor reaction. But grant, if you will, that the threshold reaction time is the same for all kinds of stimuli, and suppose that the variability is fairly constant, then, between the two extremes of stimuli, there are gradations in strength which give reaction times of widely differing variabilities. If, now, at some point in the series, as, for instance, to stimulus 2, the variability for different kinds of stimuli is the same either with reference to the reaction time (ratio) or absolutely, what interpretation is to be put upon the fact? Is it to be regarded as merely a matter of chance, and unworthy of any special attention, or should it be studied with a view to finding out precisely what variability itself signifies? It is obvious that any discussion of this subject, even of the possible or probable value of variability as a criterion for the comparative study of stimuli, can be of little value so long as we do not know what are the determining factors of variations of this sort. The only suggestion as to the meaning of such a condition (_i.e._, equal variability at some point)--and our studies seem to show it for touch and electrical stimulation--which I feel justified in offering at present, is that parity in variability indicates equality in strength of stimuli, that is, the electrical stimulus which has a reaction time of the same variability as a tactual stimulus has the same effect upon the peripheral nervous system as the tactual, it produces the same amplitude and perhaps the same form of wave, but the reaction times for the two stimuli differ because of the biological significance of the stimuli. The chances are that this is wholly dependent upon the central nervous system. IX. SUMMARY. 1. This paper gives the results of some experiments on the frog to determine its electrical and tactual reaction time. It is the beginning of comparative reaction-time studies by which it is hoped important information may be gained concerning the significance and modes of action of the nervous system. Comparative physiology has already made clear that the time relations of neural processes deserve careful study. 2. According to the strength of the stimulus, electric stimulation of the frog causes three types of reaction: (1) A very weak or threshold stimulus results in a deliberate or delayed reaction, the time of which may be anywhere from 300[sigma] (thousandths of a second) to 2,000[sigma]. (2) A very strong stimulus causes a spinal reflex, whose time is from 50 to 80[sigma]; and (3) a stimulus of intermediate strength causes a quick instinctive reaction of from 150 to 170[sigma] in duration. 3. The reaction time for electric stimuli whose relative values were 1, 2 and 4 were found to be 300.9[sigma], 231.5[sigma] and 103.1[sigma]. 4. The reaction time of the frog to a tactual stimulus (contact of a rubber point) is about 200[sigma]. 5. The variability of reaction times of the frog is great, and increases as the strength of the stimulus decreases. 6. When two kinds of stimuli (_e.g._, electrical and tactual) give reaction times of equal variability, I consider them directly comparable. 7. According to this criterion of comparability the reaction time to electric stimulation which is comparable with that to tactual is 172.1[sigma]; and it is to be compared with 205.7[sigma]. Both of these have a variability of approximately 34[sigma]. On this basis one may say that the tactual reaction time is considerably longer than the electrical. PART III. AUDITORY REACTIONS OF FROGS. X. HEARING IN THE FROG. A. Influences of Sounds in the Laboratory. After determining the simple reaction time of the green frog to tactual and electrical stimulation, I attempted to do the same in case of auditory stimuli. In this I was unsuccessful because of failure to get the animal to give a motor response which could be recorded. The animal was placed in an experimenting box with a string attached to one hind leg as in the experiments described in Part II., and after it had become accustomed to the situation a sound was made. A wide range of sounds were tried, but to none except the croak of another frog was a motor reaction frequently given. Even a loud noise, such as the explosion of a large pistol cap, caused a visible motor reaction only in rare cases. In fifty trials with this stimulus I succeeded in getting three reactions, and since all of them measured between 230 and 240[sigma] it is perhaps worth while to record the result as indicative of the auditory reaction time. As these were the only measurements obtained, I have no satisfactory basis for the comparison of auditory with other reaction times. The remarkable inhibition of movement shown by the frog in the presence of strong auditory stimulation, at least what is for the human being a strong stimulus, led me to inquire concerning the limits and delicacy of the sense of hearing in frogs. In the vast quantity of literature on the structure and functions of the sense organs of the animal I have been able to find only a few casual remarks concerning hearing. In approaching the problem of frog audition we may first examine the structure of the ear for the purpose of ascertaining what sounds are likely to affect the organ. There is no outer ear, but the membrana tympani, or ear drum, covered with skin, appears as a flat disc from 5 to 10 mm. in diameter on the side of the head just back of the eye and a little below it. In the middle ear there is but one bone, the columella, forming the connecting link between the tympanum and the internal ear. The inner ear, which contains the sense organs, consists of a membranous bag, the chief parts of which are the utriculus, the sacculus, the lagena, and the three semicircular canals. The cavity of this membranous labyrinth is filled with a fluid, the endolymph; and within the utriculus, sacculus and lagena are masses of inorganic matter called the otoliths. The auditory nerve terminates in eight sense organs, which contain hair cells. There is no cochlea as in the mammalian ear. The assumption commonly made is that vibrations in the water or air by direct contact cause the tympanic membrane to vibrate; this in turn causes a movement of the columella, which is transmitted to the perilymphatic fluid of the inner ear. The sensory hair cells are disturbed by the movements of the otoliths in the endolymph, and thus an impulse is originated in the auditory nerve which results in a sensation more or less resembling our auditory sensation. It is quite probable that the frog's sense of hearing is very different from ours, and that it is affected only by gross air vibrations. This conclusion the anatomy of the ear supports. Although there does not seem to be a structural basis for a delicate sense of hearing, one must examine the physiological facts at hand before concluding that frogs do not possess a sense of hearing similar to our own. First, the fact that frogs make vocal sounds is evidence in favor of the hearing of such sounds at least, since it is difficult to explain the origin of the ability to make a sound except through its utility to the species. Granting, however, that a frog is able to hear the croaks or pain-screams of its own species, the range of the sense still remains very small, for although the race of frogs makes a great variety of sounds, any one species croaks within a narrow range. Having satisfied myself that motor reactions for reaction-time measurements could not be gotten to any ordinary sounds in the laboratory, I tried the effect of the reflex croaking of another frog of the same species. In attempting to get frogs to croak regularly, I tested the effect of removing the brain. The animals are said to croak reflexly after this operation whenever the back is stroked; but for some reason I have never been successful in getting the reaction uniformly. In many cases I was able to make normal animals croak by rubbing the back or flanks, and to this sound the animals under observation occasionally responded by taking what looked like an attitude of attention. They straightened up and raised the head as if listening. In no case have other motor responses been noticed; and the above response was so rare that no reaction-time measurements could be made. Again, while working with the green frog on habit formation, I one day placed two animals in a labyrinth from which they could escape by jumping into a tank of water. Several times when one frog jumped into the water I noticed the other one straighten up and hold the 'listening' or 'attentive' attitude for some seconds. As the animals could not see one another this is good evidence of their ability to hear the splash made by a frog when it strikes the water. B. Influence of Sounds in Nature. In order to learn how far fear and artificial conditions were causes of the inhibition of response to sounds in the laboratory, and how far the phenomenon was indicative of the animal's inability to perceive sounds, I observed frogs in their native haunts. By approaching a pond quietly, it is easy to get within a few yards of frogs sitting on the banks. In most cases they will not jump until they have evidence of being noticed. Repeatedly I have noted that it is never possible to get near to any frogs in the same region after one has jumped in. In this we have additional proof that they hear the splash-sound. To make sure that sight was not responsible for this on-guard condition in which one finds the frogs after one of their number has jumped into the water, I made observations on animals that were hidden from one another. The results were the same. I therefore conclude that the splash of a frog jumping into the water is not only perceived by other frogs in the vicinity, but that it is a peculiarly significant sound for them, since it is indicative of danger, and serves to put them 'on watch.' A great variety of sounds, ranging in pitch from a low tone in imitation of the bull frog's croak to a shrill whistle, and in loudness from the fall of a pebble to the report of a pistol, were tried for the purpose of testing their effects upon the animals in their natural environment. To no sound have I ever seen a motor response given. One can approach to within a few feet of a green frog or bull frog and make all sorts of noises without causing it to give any signs of uneasiness. Just as soon, however, as a quick movement is made by the observer the animal jumps. I have repeatedly crept up very close to frogs, keeping myself screened from them by bushes or trees, and made various sounds, but have never succeeded in scaring an animal into a motor response so long as I was invisible. Apparently they depend almost entirely upon vision for the avoidance of dangers. Sounds like the splash of a plunging frog or the croak or pain-scream of another member of the species serve as warnings, but the animals do not jump into the water until they see some sign of an unusual or dangerous object. On one occasion I was able to walk to a spot where a large bull frog was sitting by the edge of the water, after the frogs about it had plunged in. This individual, although it seemed to be on the alert, let me approach close to it. I then saw that the eye turned toward me was injured. The animal sat still, despite the noise I made, simply because it was unable to see me; as soon as I brought myself within the field of vision of the functional eye the frog was off like a flash. Many observers have told me that frogs could hear the human voice and that slight sounds made by a passer-by would cause them to stop croaking. In no case, however, have such observers been able to assert that the animals were unaffected by visual stimuli at the same time. I have myself many times noticed the croaking stop as I approached a pond, but could never be certain that none of the frogs had seen me. It is a noteworthy fact that when one frog in a pond begins to croak the others soon join it. Likewise, when one member of such a chorus is frightened and stops the others become silent. This indicates that the cessation of croaking is a sign of danger and is imitated just as is the croaking. There is in this fact conclusive evidence that the animals hear one another, and the probability is very great that they hear a wide range of sounds to which they give no motor reactions, since they do not depend upon sound for escaping their enemies. The phenomenon of inhibition of movement in response to sounds which we have good reason to think the frogs hear, and to which such an animal as a turtle or bird would react by trying to escape, is thus shown to be common for frogs in nature as well as in the laboratory. This inhibition is in itself not surprising, since many animals habitually escape certain of their enemies by remaining motionless, but it is an interesting phenomenon for the physiologist. We have to inquire, for instance, what effects sounds which stimulate the auditory organs and cause the animal to become alert, watchful, yet make it remain rigidly motionless, have on the primary organic rhythms of the organism, such as the heart-beat, respiration, and peristalsis. It is also directly in the line of our investigation to inquire how they affect reflex movements, or the reaction time for any other stimulus--what happens to the reaction time for an electrical stimulus, for example, if a loud noise precede or accompany the electrical stimulus. For the purpose of determining the range of hearing in the frog, I was driven to study the influence of sounds upon respiration. Although the animals did not make any detectable movement, not even of an eyelid, in response to noises, it seemed not improbable that if the sounds acted as auditory stimuli at all, they would in some degree modify the form or rate of the respiratory movement. C. Influence of Sounds on Respiration.[16] [16] For full discussion of the normal respiratory movements of the frog see Martin, _Journal of Physiology,_ Vol. 1., 1878, pp. 131-170. The method of recording the respiration was the direct transference of the movement of the throat by means of a pivoted lever, one end of which rested against the throat, while the other served as a marker on a revolving drum carrying smoked paper. The frog was put into a small box, visual stimuli were, so far as possible, excluded and the lever was adjusted carefully; a record was then taken for at least half a minute to determine the normal rate of respiration in the absence of the stimulus whose effect it was the chief purpose of the experiment to discover. Then, as soon as everything was running smoothly, the auditory stimulus was given. The following records indicate the effects of a few stimuli upon the rate of breathing: 1. Stimulus, 100 V. tuning fork. Number of respirations for 10 cm. _before_ stimulus 18.0, 17.0; number of respirations for 10 cm. _after_ stimulus 19.0, 17.3. The records indicate very little change, and contradict one another. For the same stimulus the experiment was tried of taking the normal respiration record for a complete revolution of the drum, and then at once taking the record for the same length of time (about two minutes) with the tuning-fork vibrating close to the frog. The following result is typical and proves that the sound has little effect. Number of respirations in a revolution _before_ stimulus: First rev. 88; second rev. 88. Number of respirations in a revolution _during_ stimulus: First rev. 87; second rev. 88. Concerning the influence of tuning-fork stimuli more will be said later in a consideration of the effects of auditory stimuli upon reactions to visual stimuli. 2. The influence of falling water as an auditory stimulus. Water was allowed to fall about two feet in imitation, first, of a plunging frog, and second, of water falling over rocks. In representing the effect of the stimulus on the rate of respiration, I have given the distance on the drum covered by the ten complete respirations just preceding the stimulus and the ten following it. 10 Respirations. 10 Respirations. _Before_ Stimulus. _After_ Stimulus. 1st Stim. 13.0 cm. 11.8 cm. 2d Stim. 12.7 cm. 12.7 cm. With a smaller animal. 1st Stim. 5.4 cm. 4.8 cm. 2d Stim. 4.9 cm. 4.7 cm. Average for 5 5.00 cm. 4.86 cm. _These records show a marked increase in the rate of respiration just after the auditory stimulus is given for the first time._ The stimulus has less effect when repeated after an interval of one or two minutes, and if repeated several times it finally causes no noticeable change. On the whole, the sound of falling water seems to arouse the animals to fuller life. The stimulus appears to interest them, and it certainly accelerates respiration. This is precisely what one would expect from a sound which is of special significance in the life of the animal. 3. In case of a loud shrill whistle inhibition of respiration resulted. This probably means that the frogs were frightened by the sound. Falling water served rather to excite their natural-habitat associations, whereas, the whistle, being an uncommon and unassociated sound, caused fear. It is evident to the casual observer that the frog sometimes inhibits and sometimes increases its respiratory movements when frightened, so the result in this experiment is in no way surprising. I am by no means certain, however, that a longer series of observations on several individuals would give constant inhibitory results. My immediate purpose in the work was to get evidence of hearing; the respiratory changes were of secondary importance, although of such great interest that I have planned a more thorough special study of them for the future. A few sample results showing the influence of the whistle upon a small bull-frog follow: Length of 10 Resps. Length of 10 Resps. _Before_ Stimulus in cm. _After_ Stimulus in cm. 1st Stim. 6.0 6.7 2d " 5.4 6.0 3d " 5.9 5.8 1st " 4.7 5.4 2d " 4.4 4.6 As a test-check observation for comparison, the influence of a visual stimulus upon respiration was noted under the same conditions as for the auditory. Effect of turning on electric light over box. Length in cm. of 10 Resps. Length in cm. of 10 Resps. _Before_ Stimulus. _After_ Stimulus. 4.8 4.4 5.3 4.6 4.5 4.0 These results indicate an increase in the respiration rate due to the visual stimulus. 4. Of the other auditory stimuli used, the pistol-cap explosion gave very irregular results. For one animal it caused acceleration, for another inhibition. There is, however, good evidence that the sounds were heard. 5. The ringing of a bell gave results similer to those for a whistle, and the sound of a 500 S.V. tuning fork usually caused a slight increase in the rate of breathing. In these experiments I therefore have evidence, through their effects upon respiration, of the frog's ability to hear sounds ranging from 50 V. to at least 1,000 V. The croak of the green frog ranges from 100 to 200 V., so far as I have been able to determine. That of the bull frog is lower, from 50 to 75; and in the leopard frog the range is from 80 to 125. The latter is very different from the green frog in its croaking, in that it croaks whenever disturbed, whereas, the green frog rarely responds in that way to a stimulus. We are now in a position to say that the failure of frogs to give motor reactions to strong auditory stimuli is not due to their inability to be affected by the stimuli, but is a genuine inhibition phenomenon. XI. THE EFFECTS OF AUDITORY STIMULI ON VISUAL REACTIONS. Further experimental evidence of hearing was gotten from some work done to test the influence of sounds upon motor reactions to visual stimuli. Frogs, like most other amphibians, reptiles and fishes, are attracted by any small moving object and usually attempt to seize it. They never, so far as I have noticed, feed upon motionless objects, but, on the other hand, will take almost anything which moves. Apparently the visual stimulus of movement excites a reflex. A very surprising thing to those who are unfamiliar with frog habits is the fear which small frogs have of large ones. Put some green frogs or small bull frogs into a tank with large bull frogs, and the little ones will at once show signs of extreme fear; they jump about in the most excited manner and try hard to escape. The cause of their fear soon appears, since it is usually only a few minutes until the little ones are swallowed by their wide-mouthed, cannibalistic fellows. It is, moreover, well known that a bit of red flannel fastened to a hook attracts frogs and is an excellent method of capturing them. Red seems to be the color which they most readily notice. This tendency of the frog to attempt to seize any moving object I made use of to test the value of sounds. By placing a frog in a glass aquarium which was surrounded by a screen, back of which I could work and through a small hole in which I was able to watch the animal without being noticed by it, and then moving a bit of red cardboard along one side of the aquarium, I could get the frog to jump at it repeatedly. In each attempt to get the moving object, the animal struck its head forcibly against the glass side of the aquarium. There was, therefore, reason to think that a few trials would lead to the inhibition of the reaction. Experiment discovered the fact that a hungry frog would usually jump at the card as many as twenty times in rapid succession. In this reaction to a visual stimulus there appeared good material for testing audition. I therefore arranged a 500 S.V. tuning fork over the aquarium and compared the reactions of animals to the visual stimulus alone, with that to the visual stimulus when accompanied by an auditory stimulus. The tuning-fork sound was chosen because it seemed most likely to be significant to the frog. It is similar to the sounds made by the insects upon which frogs feed. For this reason one would expect that the sight of a moving object and the sound of a tuning-fork would tend to reënforce one another. The experiments were begun with observations on the effects of moving objects on the respiration. In case of a normal rate of 54 respirations per minute sight of the red object caused an increase to 58. Then the same determination was made for the auditory stimulus. The tuning-fork usually caused an increase in rate. In a typical experiment it was from 65 per minute to 76. The observations prove conclusively that the 500 S.V. sound is heard. My attention was turned to the difference of the environment of the ear in its relation to hearing. Apparently frogs hear better when the tympanum is partially under water than when it is fully exposed to the air. Having discovered by repeated trials about how vigorously and frequently a frog would react to the moving red card, I tried the effect of setting the fork in vibration a half minute before showing the card. It was at once evident that the sound put the frog on the alert, and, when the object came into view, it jumped at it more quickly and a greater number of times than when the visual stimulus was given without the auditory. This statement is based on the study of only two animals, since I was unable to get any other frogs that were in the laboratory at the time to take notice of the red cardboard. This was probably because of the season being winter. I venture to report the results simply because they were so definite as to point clearly to the phenomenon of the reënforcement of the visual-stimulus reaction by an auditory stimulus. Concerning the influence of this combining of stimuli on the reaction time, I am only able to say that the reaction to the moving object occurred quicker in the presence of the auditory stimulus. When the red card was shown it was often several seconds before the frog would notice it and attempt to get it, but when the sound also was given the animal usually noticed and jumped toward the moving card almost immediately. Unfortunately I have thus far been unable to get chronoscopic measurements of the reaction times in this reënforcement phenomenon. I hope later to be able to follow out the interesting suggestions of these few experiments in the study of reënforcement and inhibition as caused by simultaneously given stimuli. A few observations made in connection with these experiments are of general interest. The frog, when it first sees a moving object, usually draws the nictitating membrane over the eye two or three times as if to clear the surface for clearer vision. Frequently this action is the only evidence available that the animal has noticed an object. This movement of the eye-lids I have noticed in other amphibians and in reptiles under similar conditions, and since it always occurs when the animals have need of the clearest possible vision, I think the above interpretation of the action is probably correct. Secondly, the frog after getting a glimpse of an object orients itself by turning its head towards the object, and then waits for a favorable chance to spring. The aiming is accurate, and as previously stated the animal is persistent in its attempts to seize an object. XII. THE PAIN-SCREAM OF FROGS. While making measurements of the frog's reaction time to electrical stimulation, I noticed that after a few repetitions of a 2-volt, .0001-ampère stimulus an animal would frequently make a very peculiar noise. The sound is a prolonged scream, like that of a child, made by opening the mouth widely. The ordinary croak and grunt are made with closed or but slightly opened mouth. The cry at once reminds one of the sounds made by many animals when they are frightened. The rabbit, for example, screams in much the same way when it is caught, as do also pigs, dogs, rats, mice and many other animals. The question arises, is this scream indicative of pain? While studying reaction time I was able to make some observations on the relation of the scream to the stimulus. First, the scream is not given to weak stimuli, even upon many repetitions. Second, it is given to such strengths of an electrical stimulus as are undoubtedly harmful to the animal. Third, after a frog has been stimulated with a strong current (two volts), until the scream is given with almost every repetition, it will scream in the same way when even a weak stimulus is applied. If, for instance, after a two-volt stimulus has been given a few times, the animal be merely touched with a stick, it will scream. It thus appears as if the strong stimulus increases the irritability of the center for the scream-reflex to such an extent that even weak stimuli are sufficient to cause the reaction. Are we to say that the weak stimulus is painful because of the increased irritability, or may it be concluded that the reflex is in this case, like winking or leg-jerk or the head-lowering and puffing, simply a forced movement, which is to be explained as an hereditary protective action, but not as necessarily indicative of any sort of feeling. Clearly if we take this stand it may at once be said that there is no reason to believe the scream indicative of pain at any time. And it seems not improbable that this is nearer the truth than one who hears the scream for the first time is likely to think. The pain-scream is of interest in this consideration of auditory reactions because it increases the range of sounds which we should expect frogs to hear if we grant the probability of them hearing their own voices. It may be worth while to recall at this point the fact that a whistle from the human lips--the nearest approach to the pain-scream among the sounds which were used as stimuli in the experiments on respiration--caused marked inhibition of respiration. Perhaps this fact may be interpreted in the light of the pain-scream reaction. I may add that I have never seen a frog give a motor reaction to the pain-scream. Thinking it would certainly alarm the animals and cause them to make some movement which would serve for reaction-time measurements, I made repeated trials of its effects, but could never detect anything except respiratory changes. * * * * * STUDIES IN PSYCHOLOGICAL THEORY. * * * * * THE POSITION OF PSYCHOLOGY IN THE SYSTEM OF KNOWLEDGE. BY HUGO MÜNSTERBERG. The modern efforts to bring all sciences into a system or at least to classify them, from Bacon to Spencer, Wundt and Pearson have never, if we abstract here from Hegel, given much attention to those questions of principle which are offered by the science of psychology. Of course the psychological separation of different mental functions has often given the whole scheme for the system, the classification thus being too often more psychological than logical. Psychology itself, moreover, has had for the most part a dignified position in the system; even when it has been fully subordinated to the biological sciences, it was on the other hand placed superior to the totality of mental and moral sciences, which then usually have found their unity under the positivistic heading 'sociology.' And where the independent position of psychology is acknowledged and the mental and moral sciences are fully accredited, as for instance with Wundt, psychology remains the fundamental science of all mental sciences; the objects with which philology, history, economics, politics, jurisprudence, theology deal are the products of the processes with which psychology deals, and philology, history, theology, etc., are thus related to psychology, as astronomy, geology, zoölogy are related to physics. There is thus nowhere a depreciation of psychology, and yet it is not in its right place. Such a position for psychology at the head of all 'Geisteswissenschaften' may furnish a very simple classification for it, but it is one which cannot express the difficult character of psychology and the complex relations of the system of mental sciences. The historical and philological and theological sciences cannot be subordinated to psychology if psychology as science is to be coördinated with physics, that is, if it is a science which describes and explains the psychical objects in the way in which physics describes and explains the physical objects. On the other hand, if it means in this central position of mental sciences a science which does not consider the inner life as an object, but as subjective activity needing to be interpreted and subjectively understood, not as to its elements, but as to its meaning, then we should have two kinds of psychology, one which explains and one which interprets. They would speak of different facts, the one of the inner life as objective content of consciousness, as phenomenon, the other of the inner life as subjective attitude, as purpose. The fact is, that these two sciences exist to-day. There are psychologists who recognize both and keep them separated, others who hold to the one or the other as the only possible view; they are phenomenalists or voluntarists. Mostly both views are combined, either as psychological voluntarism with interposed concessions to phenomenalism or as phenomenalism with the well-known concessions to voluntarism at the deciding points. Further, those who claim that psychology must be phenomenalistic--and that is the opinion of the present writer--do not on that account hold that the propositions of voluntarism are wrong. On the contrary: voluntarism, we say, is right in every respect except in believing itself to be psychology. Voluntarism, we say, is the interpretative account of the real life, of immediate experience, whose reality is understood by understanding its meaning sympathetically, but we add that in this way an objective description can never be reached. Description presupposes objectivation; another aspect, not the natural aspect of life, must be chosen to fulfill the logical purposes of psychology: the voluntaristic inner life must be considered as content of consciousness while consciousness is then no longer an active subject but a passive spectator. Experience has then no longer any meaning in a voluntaristic sense; it is merely a complex of elements. We claim that every voluntaristic system as far as it offers descriptions and explanations has borrowed them from phenomenalistic psychology and is further filled up by fragments of logic, ethics and æsthetics, all of which refer to man in his voluntaristic aspect. We claim, therefore, that such a voluntaristic theory has no right to the name psychology, while we insist that it gives a more direct account of man's real life than psychology can hope to give, and, moreover, that it is the voluntaristic man whose purpose creates knowledge and thus creates the phenomenalistic aspect of man himself. We say that the voluntaristic theory, the interpretation of our real attitudes, in short teleological knowledge, alone can account for the value and right of phenomenalistic psychology and it thus seems unfair to raise the objection of 'double bookkeeping.' These two aspects of inner life are not ultimately independent and exclusive; the subjective purposes of real life necessarily demand the labors of objectivistic psychology. The last word is thus not dualistic but monistic and the two truths supplement each other. But this supplementation must never be misinterpreted as meaning that the two sciences divide inner experience, as if, for instance, the phenomenalistic study dealt with perceptions and ideas, the voluntaristic with feelings and volitions. No, it is really a difference of logical purpose of treatment and thus a difference of points of view only; the whole experience without exception must be possible material for both. There is no feeling and no volition which is not for the phenomenalist a content of consciousness and nothing else. There is, on the other hand, no perception and no idea which is not, or better, ought not to be for the voluntarist a means, an aim, a tool, an end, an ideal. In that real life experience of which the voluntarist is speaking, every object is the object of will and those real objects have not been differentiated into physical things under the abstract categories of mechanics on the one hand, and psychical ideas of them in consciousness on the other; the voluntarist, if he is consistent, knows neither physical nor psychical phenomena. Phenomenalist and voluntarist thus do not see anything under the same aspect, neither the ideas nor the will. This difference is wrongly set forth if the antithesis to voluntarism is called intellectualism. Intellectualism is based on the category of judgment, and judgment too is a ideological attitude. Phenomenalism does not presuppose a subject which knows its contents but a subject which simply _has_ its contents; the consciousness which has the thought as content does not take through that the voluntaristic attitude of knowing it and the psychologist has therefore no reason to prefer the thought to the volition and thus to play the intellectualist. If the psychologist does emphasize the idea and its elements, the sensations, it is not because they are vehicles of thought but because their relations to physical objects make them vehicles of communication. The elements of ideas are negotiable and thus through their reference to the common physical world indirectly describable; as the elements of ideas are alone in this position, the psychologist is obliged to consider all contents of consciousness, ideas and volitions alike, as complexes of sensations. The antithesis is also misinterpreted, or at least wrongly narrowed, if it is called voluntarism _versus_ associationism. Recent discussions have sufficiently shown that the principle of association is not the only possible one for phenomenalistic theories. If associationism is identified with objective psychology, all the well-founded objections to the monopoly of the somewhat sterile principle of association appear as objections to phenomenalism in psychology, and voluntaristic theories, especially those which work with the teleological category of apperception, are put in its place. But without returning to apperceptionism we can overcome the one-sidedness of associationism if full use is made of the means which the world of phenomena offers to theory. The insufficiency of associationism disappears if the content of consciousness is considered as variable not only as to quality and intensity but also as to vividness. This variation of vividness, on the other hand, is no exception from the psychophysical parallelism as soon as the psychical process is considered as dependent not only upon the local and quantitative differences of the sensory process but also upon the motor function of the central physical process. The one-sidedness of the physiological sensory theories has been the hidden reason for the one-sidedness of associationism. The sensory-motor system must be understood as the physical basis of the psychophysical process and the variations in the motor discharge then become conditions of those psychical variations of vividness which explain objectively all those phenomena in whose interest associationism is usually supplemented by apperceptionism. The association theory must thus be given up in favor of an 'action-theory'[1] which combines the consistency of phenomenalistic explanation with a full acknowledgment of the so-called apperceptive processes; it avoids thus the deficiency of associationism and the logical inconsistency of apperceptionism. [1] H. Münsterberg, 'Grundzüge der Psychologie.' Bd. I., Leipzig, 1900, S. 402-562. Only if in this way the sciences of voluntaristic type, including all historical and normative sciences, are fully separated from phenomenalistic psychology, will there appear on the psychological side room for a scientific treatment of the phenomena of social life, that is, for sociology, social psychology, folk-psychology, psychical anthropology and many similar sciences. All of them have been in the usual system either crowded out by the fact that history and the other mental sciences have taken all the room or have been simply identified with the mental sciences themselves. And yet all those sciences exist, and a real system of sciences must do justice to all of them. A modern classification has perhaps no longer the right as in Bacon's time to improve the system by inventing new sciences which have as yet no existence, but it has certainly the duty not to ignore important departments of knowledge and not to throw together different sciences like the descriptive phenomenalistic account of inner life and its interpretative voluntaristic account merely because each sometimes calls itself psychology. A classification of sciences which is to be more than a catalogue fulfills its logical function only by a careful disentanglement of logically different functions which are externally connected. Psychology and the totality of psychological, philosophical and historical sciences offer in that respect far more difficulty than the physical sciences, which have absorbed up to this time the chief interest of the classifier. It is time to follow up the ramifications of knowledge with special interest for these neglected problems. It is clear that in such a system sciences which refer to the same objects may be widely separated, and sciences whose objects are unlike may be grouped together. This is not an objection; it indicates that a system is more than a mere pigeon-holing of scholarly work, that it determines the logical relations; in this way only can it indeed become helpful to the progress of science itself. The most direct way to our end is clearly that of graphic representation wherein the relations are at once apparent. Of course such a map is a symbol and not an argument; it indicates the results of thought without any effort to justify them. I have given my arguments for the fundamental principles of the divisions in my 'Grundzüge der Psychologie' and have repeated a few points more popularly in 'Psychology and Life,' especially in the chapter on 'Psychology and History.' And yet this graphic appendix to the Grundzüge may not be superfluous, as the fulness of a bulky volume cannot bring out clearly enough the fundamental relations; the detail hides the principles. The parallelism of logical movements in the different fields especially becomes more obvious in the graphic form. Above all, the book discussed merely those groups which had direct relation to psychology; a systematic classification must leave no remainder. Of course here too I have not covered the whole field of human sciences, as the more detailed ramification offers for our purpose no logical interest; to subdivide physics or chemistry, the history of nations or of languages, practical jurisprudence or theology, engineering or surgery, would be a useless overburdening of the diagram without throwing new light on the internal relations of knowledge. Without now entering more fully into any arguments, I may indicate in a few words the characteristic features of the graphically presented proposition. At the very outset we must make it clear that phenomena and voluntaristic attitudes are not coördinated, but that the reality of phenomena is logically dependent upon voluntaristic attitudes directed towards the ideal of knowledge. And yet it would be misleading to place the totality of phenomenalistic sciences as a subdivision under the teleological sciences. Possible it would be; we might have under the sciences of logical attitudes not only logic and mathematics but as a subdivision of these, again, the sciences which construct the logical system of a phenomenalistic world--physics being in this sense merely mathematics with the conception of substance added. And yet we must not forget that the teleological attitudes, to become a teleological science, must be also logically reconstructed, as they must be teleologically connected, and thus in this way the totality of purpose-sciences might be, too, logically subordinated to the science of logic. Logic itself would thus become a subdivision of logic. We should thus move in a circle, from which the only way out is to indicate the teleological character of all sciences by starting not with science but with the strictly teleological conception of life--life as a system of purposes, felt in immediate experience, and not as the object of phenomenalistic knowledge. Life as activity divides itself then into different purposes which we discriminate not by knowledge but by immediate feeling; one of them is knowledge, that is, the effort to make life, its attitudes, its means and ends a connected system of overindividual value. In the service of this logical task we connect the real attitudes and thus come to the knowledge of purposes: and we connect the means and ends--by abstracting from our subjective attitudes, considering the objects of will as independent phenomena--and thus come to phenomenalistic knowledge. At this stage the phenomenalistic sciences are no longer dependent upon the teleological ones, but coördinated with them; physics, for instance, is a logical purpose of life, but not a branch of logic: the only branch of logic in question is the philosophy of physics which examines the logical conditions under which physics is possible. One point only may at once be mentioned in this connection. While we have coördinated the knowledge of phenomena with the knowledge of purposes we have subordinated mathematics to the latter. As a matter of course much can be said against such a decision, and the authority of most mathematicians would be opposed to it. They would say that the mathematical objects are independent realities whose properties we study like those of nature, whose relations we 'observe,' whose existence we 'discover' and in which we are interested because they belong to the real world. All that is true, and yet the objects of the mathematician are objects made by the will, by the logical will, only, and thus different from all phenomena into which sensation enters. The mathematician, of course, does not reflect on the purely logical origin of the objects which he studies, but the system of knowledge must give to the study of the mathematical objects its place in the group where the functions and products of logical thought are classified. The arithmetical or geometrical material is a free creation, and a creation not only as to the combination of elements--that would be the case with many laboratory substances of the chemist too--but a creation as to the elements themselves, and the value of the creation, its 'mathematical interest,' is to be judged by ideals of thought, that is, by logical purposes. No doubt this logical purpose is its application in the world of phenomena, and the mathematical concept must thus fit the world so absolutely that it can be conceived as a description of the world after abstracting not only from the will relations, as physics does, but also from the content. Mathematics would then be the phenomenalistic science of the form and order of the world. In this way mathematics has a claim to places in both fields: among the phenomenalistic sciences if we emphasize its applicability to the world, and among the teleological sciences if we emphasize the free creation of its objects by the logical will. It seems to me that a logical system as such has to prefer the latter emphasis; we thus group mathematics beside logic and the theory of knowledge as a science of objects freely created for purposes of thought. All logical knowledge is divided into Theoretical and Practical. The modern classifications have mostly excluded the practical sciences from the system, rightly insisting that no facts are known in the practical sciences which are not in principle covered by the theoretical sciences; it is art which is superadded, but not a new kind of knowledge. This is quite true so far as a classification of objects of knowledge is in question, but as soon as logical tasks as such are to be classified and different aspects count as different sciences, then it becomes desirable to discriminate between the sciences which take the attitude of theoretical interest and those which consider the same facts as related to certain human ends. But we may at first consider the theoretical sciences only. They deal either with the objectified world, with objects of consciousness which are describable and explainable, or with the subjectivistic world of real life in which all reality is experienced as will and as object of will, in which everything is to be understood by interpretation of its meaning. In other words, we deal in one case with phenomena and in the other with purposes. The further subdivision must be the same for both groups--that which is merely individual and that which is 'overindividual'; we prefer the latter term to the word 'general,' to indicate at once that not a numerical but a teleological difference is in question. A phenomenon is given to overindividual consciousness if it is experienced with the understanding that it can be an object for every one whom we acknowledge as subject; and a purpose is given to overindividual will in so far as it is conceived as ultimately belonging to every subject which we acknowledge. The overindividual phenomena are, of course, the physical objects, the individual phenomena the psychical objects, the overindividual purposes are the norms, the individual purposes are the acts which constitute the historical world. We have thus four fundamental groups: the physical, the psychological, the normative and the historical sciences. Whoever denies overindividual reality finds himself in the world of phenomena a solipsist and in the world of purposes a sceptic: there is no objective physical world, everything is my idea, and there is no objective value, no truth, no morality, everything is my individual decision. But to deny truth and morality means to contradict the very denial, because the denial itself as judgment demands acknowledgment of this objective truth and as action demands acknowledgment of the moral duty to speak the truth. And if an overindividual purpose cannot be denied, it follows that there is a community of individual subjects whose phenomena cannot be absolutely different: there must be an objective world of overindividual objects. In each of the four groups of sciences we must consider the facts either with regard to the general relations or with regard to the special material; the abstract general relations refer to every possible material, the concrete facts which fall under them demand sciences of their own. In the world of phenomena the general relations are causal laws--physical or psychical laws; in the world of purposes theories of teleological interrelations--normative or historical; the specific concrete facts are in the world of phenomena objects, physical or psychical objects, in the world of purposes acts of will--specific norms or historical acts. If we turn first to phenomena, the laws thereof are expressed in the physical sciences, by mechanics, physics, chemistry, and we make mechanics the superior as chemistry must become ultimately the mechanics of atoms. In the psychological sciences the science of laws is psychology, with the side-branch of animal psychology, while human psychology refers to individuals and to social groups. Social psychology, as over against individual psychology, is thus a science of general laws, the laws of those psychological phenomena which result from the mutual influence of several individuals. On the other hand, we have as the special concrete products of the laws, the objects themselves, and the most natural grouping of them may be from whole to part. In the physical world it means that we start from the concrete universe, turning then to the earth, then to the objects on the earth, inorganic and organic. There is here no logical difficulty. Each one of these objects can be considered in three aspects, firstly as to its structure, secondly as to its special laws, that is, the special function of the object as related to the general sciences of physics and chemistry, and thirdly as to its natural development. If we apply these three methods of study to the whole universe we have astronomy, astrophysics and cosmology, to the whole earth, geography, geophysics, geology, to animals, zoölogy, physiology, comparative anatomy, and so on. The special phenomena in the framework of the psychological sciences group themselves in the same logical order, from the whole to the part. The psychological totality is empirical mankind, and as we select the earth as the one part of the universe which is the habitat of man, so our scientific interest must move from the whole psychical humanity to those phenomena of human life which are the vehicle of our civilization, from mankind to its most important function, the association of man; and as we moved from earth to the special objects on earth, so we may turn from association to the special phenomena which result from association. If we separated further the inorganic from the organic, we must here separate the products of undifferentiated and of differentiated association. The science of mankind is race psychology, the science of the association of man is sociology, the science of the results of undifferentiated association is Völkerpsychologie, folk psychology. The science of products of differentiated association has no special name; its subject matter is the whole of historical civilization considered as a psychological naturalistic phenomenon. As soon as we follow the ramification still further we have to do with the special kinds of these products, that is, with the volitions, thoughts, appreciations and beliefs. In the undifferentiated associations they give us morals and habits, languages and enjoyments and mythological ideas, while the individually differentiated association gives political, legal and economic life, knowledge, art and religion: all of course merely as causal, not as teleological processes, and thus merely as psychological and not as historical material. Here, as with the physical phenomena, the structure, the special laws and the development must be everywhere separated, giving us three sciences in every case. For instance, the study of mankind deals with the differences of mental structure in psychical anthropology, with the special psychical laws in race psychology and with the development in comparative psychology. The chief point for us is that social psychology, race psychology, sociology, folk psychology, etc., are under this system sharply differentiated sciences and that they do not at all overlap the real historical sciences. There is no historical product of civilization which does not come under their method but it must be conceived as a causal phenomenon, not as related to the purposes of the real man, and thus even the development means merely a growing complication of naturalistic processes and not history in the teleological sense. We turn to the normative sciences. The general theory of the overindividual purposes is metaphysics; the special overindividual acts are those which constitute the normative volitions, connected in the philosophy of morals, the philosophy of state and the philosophy of law, those which constitute the normative thoughts and finally those which constitute the normative appreciations and beliefs, connected in æsthetics and the philosophy of religion. Especial interest belongs to the philosophy of thought. We have discussed the reasons why we group mathematics here and not among the phenomenalistic sciences. We have thus one science which deals critically with the presuppositions of thought, _i.e._ the theory of knowledge or epistemology, which can be divided into the philosophy of physical sciences, the philosophy of psychological sciences, the philosophy of normative sciences and the philosophy of historical sciences. We have secondly the science of the processes of thought dealing with concepts, judgments and reasoning, _i.e._, logic, and we have finally the science of those objects which the thought creates freely for its own purposes and which are independent from the content of the world, _i.e._, mathematics, which leads to the qualitative aspect of general mathematics and the quantitative aspect of concrete mathematics. For our purposes it may be sufficient to separate externally algebra, arithmetic, analysis and geometry. In this way all the philosophical sciences find their natural and necessary place in the system, while it has been their usual lot to form an appendix to the system, incommensurable with the parts of the system itself, even in the case that the other scheme were not preferred, to make ethics, logic, æsthetics, epistemology and metaphysics merely special branches of positivistic sociology and thus ultimately of biology. In the historical sciences the general theory which stands over against the special acts has a special claim on our attention. We may call it the philosophy of history. That is not identical with the philosophy of historical sciences which we mentioned as a part of epistemology. The philosophy of historical sciences deals with the presuppositions by which historical teleological knowledge becomes logically possible. The philosophy of history seeks a theory which connects the special historical acts into a unity. It has two branches. It is either a theory of the personality, creating a theory of real individual life as it enters as ideological factor into history, or it seeks the unity of entire humanity. The theory of personality shows the teleological interrelation of our purposes; the theory of humanity shows the teleological interrelation of all nations. The name philosophy of history has been used mostly for the theory of humanity only, abstracting from the fact that it has been often misused for sociology or for the psychology of history or for the philosophy of historical sciences--but the name belongs also to the theory of personality. This theory of personality is exactly that second kind of 'psychology' which does not describe and does not explain but which interprets the inner teleological connections of the real man. It is 'voluntaristic psychology' or, as others call it who see correctly the relation of this science to history, 'historical psychology.' It is practically 'apperceptionistic psychology.' The special activities of the historical man divide themselves again into volitions, thoughts, appreciations and beliefs, with their realization in the state, law, economical systems, knowledge, art and religion. Each of these special realizations must allow the same manifoldness in treatment which we found with the special physical or psychical objects; we can ask as to structure, relation to the general view and development. But in accordance with the teleological material the study of the structure here means 'interpretation,' the study of the general relations here means study of the relation to civilization, and the study of the development here means the real history. We have, thus, for the state or law or economy or knowledge or art or religion always one science which interprets the historical systems of state, etc., in a systematic and philological way, one science which deals with its function in the historical world and one which studies biographically and nationally the history of state, law, economical life, science, art or religion. In the sphere of the practical sciences the divisions of the theoretical sciences must repeat themselves. We have thus applied physical, applied psychological, applied normative and applied historical sciences, and it is again the antithesis of psychological and of historical sciences which is of utmost importance and yet too often neglected. The application of physical sciences, as in engineering, medicine, etc., or the application of normative knowledge in the sciences of criticism do not offer logical difficulty, but the application of psychological and historical knowledge does. Let us take the case of pedagogy or of penology, merely as illustrations. Is the application of phenomenalistic psychology or the application of teleological voluntarism in question? Considering the child, the criminal, any man, as psychophysical apparatus which must be objectively changed and treated, we have applied psychology; considering him as subject with purposes, as bearer of an historical civilization whose personalities must be interpreted and understood and appreciated, then we need applied historical knowledge. In the first case the science of pedagogy is a psycho-technical discipline which makes education mechanical and deprives the teacher of the teleological attitude of inner understanding; in the second case it is a science of real education far removed from psychology. All the sciences which deal with service in the system of civilization, service as teacher, as judge, as social helper, as artist, as minister, are sciences which apply the teleological historical knowledge, and their meaning is lost if they are considered as psycho-technical sciences only. LIFE (in its immediate reality, felt as a system of telelogical | experiences, involving the acknowledgement of other subjects of | experiences) | |-VOLITION (will aiming towards new experiences). | |-Individual: _Practical Life._ | |-Overindividual: _Mortality._ | |-THOUGHT (will acknowledging the connection of experiences). | |-Individual: _Judgement_ | |-Overindividual: TRUTH | |-THEORETICAL KNOWLEDGE (connection of experiences determined by | | | pure experience). | | | | | |-KNOWLEDGE OF PHENOMENA (connection of experiences after | | | | abstracting their will relations). | | | |-Knowledge of Phenomena Given to Overindividual Consciousness. | | | | |-I. PHYSICAL SCIENCES. | | | | |-A. GENERAL LAWS. | | | | | |-Mechanics. | | | | | |-Physics. | | | | | |-Chemistry. | | | | | | | | | |-B. SPECIAL OBJECTS. | | | | |-1. Universe. | | | | | |-Astronomy _a, b, c_. | | | | | | | | | |-2. Special Parts. | | | | | |-Geography _a, b, c_. | | | | | | | | | |-3. Special Objects on Earth. | | | | |-Inorganic. | | | | | |-Mineralogy _a, b, c_. | | | | | | | | | |-Organic. | | | | |-Plants. | | | | | |-Botany _a, b, c_. | | | | | | | | | |-Animals. | | | | |-Zoology _a, b, c_. | | | | |-Anthropology _a, b, c_. | | | | | | | |-Knowledge of Phenomena given to Indiviual Consciousness. | | | |-II. PSYCHOLOGICAL SCIENCES. | | | |-A. GENERAL LAWS. | | | | |-PHENOMENALISTIC PSYCHOLOGY | | | | |-Animal Psychology. | | | | |-Human psychology. | | | | |-Individual Ps. | | | | |-Normal. | | | | | |-Child. | | | | | |-Adult. | | | | | | | | | |-Abnormal. | | | | | | | |-B. SPECIAL OBJECTS. | | | |-1. Mankind. | | | | |-Race Psychology _a, b, c_. | | | |-2. Special Functions. | | | | |-Association of Men. | | | | |-Sociology _a, b, c_. | | | | | | | |-3. Special Products of Association of Men | | | | (considered as natural phenomena). | | | |-Products of Undiffereniated Association of Men | | | | | (Folk Psychology). | | | | |-Volition. | | | | | |-Morals _a, b, c_. | | | | | |-Habits _a, b, c_. | | | | | | | | | |-Thoughts. | | | | | |-Languages _a, b, c_. | | | | | | | | | |-Appreciation. | | | | | |-Enjoyment _a, b, c_. | | | | | | | | | |-Belief. | | | | |-Mythology _a, b, c_. | | | | | | | |-Products of Individual Differentiation | | | | (casual phenomenalistic sciences of civilization | | | | and its development). | | | |-Volition. | | | | |-State _a, b, c_. | | | | |-Law _a, b, c_. | | | | |-Economy _a, b, c_. | | | | | | | |-Thoughts. | | | | |-Sciences _a, b, c_. | | | | | | | |-Appreciation. | | | | |-Art _a, b, c_. | | | | | | | |-Belief. | | | |-Religion _a, b, c_. | | | | | |-KNOWLEDGE OF PURPOSES (connection of experiences in their | | | telelogical reality). | | | | | |-Knowledge of Purposes of the Overindividual Will. | | | |-III. NORMATIVE SCIENCES | | | |-A. GENERAL THEORY of absolute values. | | | | |-Metaphysics. | | | | | | | |-B. SPECIAL ACTS. | | | |-Volition. | | | | |-Philosophy of Morals (Ethics). | | | | |-Philosophy of Law. | | | | |-Philosophy of State. | | | | | | | |-Thoughts. | | | | |-Presuppositions of Thought. | | | | | |-Theory of Knowledge. | | | | | |-Phil. of Physics. | | | | | |-Phil. of Psych. | | | | | |-Phil. of Normative Sciences. | | | | | |-Phil. of Historical Sciences. | | | | | | | | | |-Processes of Thought. | | | | | |-Logic. | | | | | | | | | |-Objects Created by Thought. | | | | |-Mathematics. | | | | |-Algebra. | | | | |-Arithmetic. | | | | |-Analysis. | | | | |-Geometry. | | | | | | | |-Appreciation. | | | | |-Philosophy of Art (Æsthetics). | | | | | | | |-Belief. | | | |-Philosophy of Religion. | | | | | |-Knowledge of Purposes of the Individual Will. | | |-IV. HISTORICAL SCIENCES. | | |-A. GENERAL THEORY of real life. | | | |-Philosophy of History. | | | |-Theory of Personality. | | | | |-(Theory of selves.) | | | | |-("Historical Psychology.") | | | | |-("VOLUNTARISTIC Psychology.") | | | | |-("Apperceptional Psychology.") | | | |-Theory of Humanity. | | | | | |-B. SPECIAL ACTS (telelogical interpretative sciences of | | | civilization and history.) | | |-Volition. | | | |-Politics, _a, b, c_. | | | |-Law, _a, b, c_. | | | |-Economy, _a, b, c_. | | | | | |-Thoughts. | | | |-Science, _a, b, c_. | | | | | |-Appreciation. | | | |-Art, _a, b, c_. | | | | | |-Belief. | | |-Religion, _a, b, c_. | | | |-PRACTICAL KNOWLEDGE. | |-APPLIED KNOWLEDGE OF PHENOMENA. | | |-V. APPLIED PHYSICAL SCIENCES. | | | |-Technical Sciences. | | | | |-Applied Physics. | | | | |-Applied Chemistry. | | | | |-Applied Biology. | | | | | | | |-Medicine. | | | | | |-VI. APPLIED PSYCHOLOGICAL SCIENCES. | | |-Psychotechnical Sciences. | | | |-Psychological Pedagogy. | | | |-Psychological Penology. | | | | | |-Psychiatry. | | | |-APPLIED KNOWLEDGE OF PURPOSES. | |-VII. APPLIED NORMATIVE SCIENCES. | | |-Volition. | | | |-Politics. | | | | |-Science of Public Service. | | | | | | | |-Law. | | | | |-Science of Legal Service. (Practical Jurisprudence.) | | | | | | | |-Economy. | | | |-Science of Social Service. | | | | | |-Thoughts. | | | |-Science of Teaching. (Education.) | | | | | |-Appreciation. | | | |-Science of Artistic Production. | | | | | |-Belief. | | |-Science of Religious Service. (Practical Theology.) | | | |-VIII. APPLIED HISTORICAL SCIENCES. | |-Volition. | | |-Criticism of State. | | |-Criticism of Law. | | | |-Thoughts. | | |-Criticism of Science. | | | |-Appreciation. | | |-Criticism of Art. | | | |-Belief. | |-Criticism of Religion. | |-APPRECIATION (will resting in isolated experiences). | |-Individual: _Enjoyment._ | |-Overindividual: _Beauty._ | |-BELIEF (will resting in the supplements of experience). |-Individual: _Creed._ |-Overindividual: _Religion. NOTE: The letters _a, b, c_ below the sciences of Special Objects and Special Acts indicate the three subdivisions that results from the threefold aspects;--of structure(_a_), of relation to the general laws or theories(_b_), and of development(_c_). With regards to physical phenomena, for instances, we have astronomy(_a_), astrophysics(_b_), and cosmology(_c_); or geography(_a_), geophysics(_b_), geology(_c_); or botany(_a_), plant physiology(_b_), phylogenetic development of plants(_c_). In the same way for psychical objects; for instance: structural sociology(_a_), functional sociology(_b_), comparative sociology(_c_); or structure (grammar and syntax) of languages(_a_), psychology of languages(_b_), comparative study of languages(_c_). With regard to the telelogical historical sciences the study of structure takes on here the character of intrepretation; the relation to the general view is here the dependence on civilization and the development is here the real history. We have thus, for instance, the intepretation of Roman law(_a_), dependence of Roman law upon civilization(_b_), history of Roman law(_c_).