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STUDIES FR0I.;1 THE PSYCHOLOGICAL LABOR.\TORY 
 OF THE 
 UKIVERSITY OF CALIFORIIIA 
 
 REPRINTED FROM 
 THE' PSYCHOLOGICAL REVIEW 
 

 LIBRARY 
 
 EDUC. 
 
 PSYCH. 
 
 LIBRARY 
 
 Ss^ 
 
CONTENTS 
 
 Study 
 
 I. St rat ton, George ¥, 
 
 A new determination of the mirjimiim 
 visible and its bearing on locali- 
 zation and binocular depth. 
 
 TI. 
 
 Dunlap, Knight 
 
 The effect of imperceptible shadows 
 on, the judgment of. distance. 
 
 III. Stratton, George ¥, 
 
 Visible motion and the space thres- 
 hold. 
 
 IV. Stratton, George M. 
 
 The method of serial groups. 
 
 V, Nelson, I:abel Lorena. 
 
 The effect of subdivisions on the 
 visual estimate of time. 
 
 VI. Robe i-t son, Alice. 
 
 * Geometric -Optical' illusions in 
 touch. 
 
 VII. 
 
 Brand, Joseph E. 
 
 The effect of verbal suf^gesti 
 upon the estimation of linear 
 magnitudes. 
 
 ons 
 
 Manchester, Genevieve Savage. 
 
 Experiments on the unreflective 
 ideas of men and women. 
 
 M 3584 
 
-CONTEOTS 
 
 Study 
 
 IX, Nelson, Mabel Lorena. 
 
 The difference between men and women 
 in the recognition of color and the 
 perception of sound. 
 
 X. Dunlap, Knight. 
 
 Extensity and pitclu 
 
 XI. Jones, Grace Mildred. 
 
 Experiments on the reproduction of 
 distance as influenced by suggestions 
 of ability and inability. 
 
 XII. Strong, E. K. 
 
 The effect of various types of sugges- 
 tion upon muscular activity. 
 
 XIII. Stratton, George M, 
 
 The localization of diasclerotic light. 
 
 XIV. Brewer, John M. 
 
 The psychology of change: On some phases 
 of ^minimal time by sight. 
 
 XV. Stratton, George M 
 
 The psychology of change: • How is the 
 percept; ion of movement related to that 
 of succession? 
 
 XVI. Brown, V\famer. 
 
 Temporal and accentual rhythm. 
 
 XVII. Stockton, M. I. 
 
 Soitie preferences by boys and girls as 
 shown in their choice of words. 
 
REPRINTED FROM 
 
 VOL VII. No. 5. September, 1900. 
 
 THE 
 
 Psychological Review 
 
 EDITED BY 
 J. McKEEN CATTELL J. MARK BALDWIN 
 
 AND 
 
 Columbia University Princeton Lnivbrsity 
 
 ivith the co-operation of 
 
 ALFRED BINET, ficoLE des Hautes-£tudes, Paris; JOHN DEWEY, H. H. DONALD- 
 SON, University of Chicago; G. S. FULLERTON, University of Pennsylvania; 
 G. H. HOWISON, University of California; JOSEPH JASTROW, Uni- 
 versity OF Wisconsin; G. T. LADD, Yale University; HUGO 
 MUNSTERBERG, Harvard University; M. ALLEN STARR, 
 College of Physicians and Surgeons, New York: CARL 
 STUMPF, University, Berun; JAMES SULLY, 
 University College, Ixindon. 
 
 STUDIES FROM THE PSYCHOLOGICAL LABORATORY 
 OF THE UNIVERSITY OF CALIFORNIA. 
 
 I. A New Determination of the Minimum Visibile and its Bearing 
 ON Localization and Binocular Depth. 
 
 BY PROFESSOR GEORGE M. STRATTON, 
 
 II. The Effect of Imperceptible Shadows ox the Judgment 
 
 OF Distance. 
 
 BY KNIGHT DUNLAP. 
 
 PUBLISHBO BI- monthly BY 
 
 THE MACMILLAN COMPANY, 
 
 41 N. QUEEN ST., LANCASTER, PA. 
 66 FIFTH AVENUE, NEW YORK. 
 
[Reprinted from The Psychological Review, Vol. VII., No. S, Sept., 1900.] 
 
 STUDIES FROM THE PSYCHOLOGICAL LABORA- 
 TORY OF THE UNIVERSITY OF CALIFORNIA. 
 
 I. A New Determination of the Minimum Visible and 
 ITS Bearing on Localization and Bin- 
 ocular Depth. 
 
 BY professor GEORGE M. STRATTON. 
 
 The smallest lateral difference of place that is visible has 
 until recently been given as about 5o''-6o'' angular measure. 
 The method employed by Helmholtz and others ^ in reaching 
 this result was the well-known one of bringing two parallel 
 lines together until they finally are just distinguished as two — 
 on the same general principle by which Weber determined the 
 tactile space-threshold, by finding the distance between two 
 compass-points that just cease to merge into one. 
 
 But by a different method it is now evident that a lateral 
 difference ^ of place of about 7" of arc can be directly perceived. 
 
 Instead of using lines or points side-by-side, the experi- 
 ments which give this result were made with lines end-to-end, 
 so arranged that the upper of two perpendiculars could be 
 moved at will to the right or left while still remaining exactly 
 parallel to the lower line, as shown in Fig. i. The observer 
 had simply to judge whether the upper line was continuous 
 with the lower, or to which side it had been displaced. In the 
 initial trials the lines were narrow slits of light surrounded by 
 
 'See Helmholtz : Phystologische Optik, 2d ed., pp. 256 et seq. 
 *In contrast with a difference in depth or a difference not of itself percep- 
 tible, but evident merelj' by reason of stereoscopic effect. 
 
 Psjfchoiogical Laboratof). 
 
ni'^, .'':'./' ':: ..i:'-^'?^ 
 
 GEORGE M. STRATTON. 
 
 a black ground — each line not more than half a millimeter 
 wide and some lo cm. long, and observed in a half-darkened 
 
 room from a distance of i8 meters. 
 But the surprising fineness of discrim- 
 ination made it impossible to work 
 with accuracy from so short a distance ; 
 so that finally the observer was placed 
 120 meters away, and the lines were 
 changed to narrow white strips, part 
 of the time lo mm., part of the time 
 8 mm., wide, each 50 cm. long, on a 
 dull-black ground. Each line with 
 its ground was mounted on the face 
 of a plate of glass, the two glasses 
 placed edge to edge in a frame ; and, 
 Fig. I. by sliding the upper plate upon the 
 
 lower, lateral shifts were made by steps 
 of I mm. At first the ordinary procedure of ' minimal changes ' 
 was adopted, but it soon became clear that suggestion was play- 
 ing too large a role, and resort was had to a compromise be- 
 tween this method and that of ' right-and-wrong cases,' which 
 might be called a method of serial groups, to be described more 
 fully at another time. Taking as the threshold the point where 
 8ofo, or more, of correct judgments occurred, the following re- 
 sults were obtained : 
 
 Subject A. (187 judgments). 
 
 Thresholds for Displacements to the 
 Right. Left. 
 
 2. mm. 
 4- " 
 3- '■ 
 Aver. 3. mm. 
 
 General average 4.1 mm. 
 
 5. mm. 
 
 6. " 
 
 5- " 
 Aver. 5.3 mm. 
 
 Subject D. (277 judgments). 
 
 Thresholds for Displacements to the 
 Right Left. 
 
 4. mm. 
 
 6. mm 
 
 3- " 
 
 2. " 
 
 5. " 
 5- " 
 
 ver. 3.2 " Aver. 
 General average 4.2 mm 
 
 5- " 
 5.2 " 
 
CALIFORNIA PSYCHOLOGICAL LABORATORY. 43 1 
 
 Taking i mm. as equivalent, approximately, to 1.7 seconds 
 of arc, where the radius is 120 m., we get a fraction over 7 sec- 
 onds as the threshold of space-distinction under these conditions. 
 
 The experiments were begun with some doubt whether there 
 was a direct perception of a spatial difference here ; whether, 
 for instance, some purely intensive change — some apparent 
 dimming or strengthening of the impression from the adjacent 
 ends of the lines where the displacement occurred — might not 
 serve to suggest indirectly a spatial inequality. But anyone 
 making the observation is soon convinced that what he sees is 
 not of this character, but that the two lines seem to form a 
 single line no longer straight. He seems to compare the posi- 
 tion of one of the lines with an imaginary extension of the 
 other, and to notice that the two, in this way, do not coincide. 
 As a check, however, the observers throughout the experiments 
 were kept in ignorance of the actual direction of the displace- 
 ments, and the threshold was not considered as reached until the 
 direction could be told by them ; so that if their judgments had 
 been based on anything other than the perceptible position of the 
 lines, the fact of a break or shift in general might perhaps have 
 been inferred, from some intensive difference in the light, but it 
 is difficult to see how, from that alone, the subjects would have 
 been able to tell correctly to which side the line had been moved. 
 There seems, moreover, to be nothing inherently suspicious in 
 the striking disparity between these results and those obtained 
 by the older method. In the threshold obtained in Helmholtz's 
 way these finer measurements are not reached simply because 
 the diffusion of the stimulus from the two lines side-by-side 
 makes a fairly uniform blur on the retina between them, and 
 within the limits of the blur two separate objects can no longer 
 be [distinguished. But when the lines are arranged as in the 
 present experiment, any such interference by mere diffusion is 
 greatly lessened, and the localities can be clearly and correctly 
 distinguished. 
 
 The result thus obtained is interesting in several ways. In 
 the first place, it^probably removes the grounds for inferring, 
 as yet, that stereoscopic depth at its minimum is a subconscious 
 result of the spatial conflict of the two images. M.y own ex- 
 
432 GEORGE M. STRATTON. 
 
 periments with the pseudoscope * had shown that an angular 
 difference of 24 seconds between the two impressions was suffi- 
 cient to give a binocular relief. Still later, Bourdon,^ experi- 
 menting with needles at short range, found that a difference 
 amounting to but five seconds produces a perceptible depth- 
 effect. As long as the conscious lateral threshold was counted 
 as above 60 seconds, one would be tempted from these results 
 to believe either that stereoscopic depth was not due primaril}^ 
 to a lateral space-discrimination of the two images, or else that 
 the plastic effect must depend on a subconscious action, since 
 the disparities in the image were smaller than could be con- 
 sciously noted. The present reduction of the conscious lateral 
 threshold to about 7 seconds leaves but a small margin upon 
 which to base such conclusions, particularly when one takes 
 into account the wide contrasts in the (non-essential) conditions 
 of the experiments. Bourdon would seem entirely justified, 
 however, in concluding that binocular depth cannot be due to 
 our detecting double images, if by double images we are to 
 understand outlines that are distinguishable side-hy-side. But 
 the depth-effect may still be due to the presence of double im- 
 ages in the sense of outlines that are felt not to be coincident 
 when positions are compared end-to-end. There certainl}'- is a 
 difficulty in that ordinary stereoscopic vision seems hardly to 
 provide the conditions for comparing outlines in this way. It 
 is barely possible, however, that the curious phenomenon of 
 retinal rivalry may be useful just herein, that by the successive 
 emerging and disappearance of parts of the outlines in the two 
 projected fields of view something comparable to the condi- 
 tions of the present experiment is brought about, and an ex- 
 ceedingly fine perception of lateral incongruity results. 
 
 But perhaps a more important bearing of the experiment is 
 on the general problem of visual localization. It seems highly 
 improbable that so minute a displacement is discerned by no- 
 ting some muscular jog or unevenness in running our eyes up 
 and down the line, when one recalls that the fovea itself is some 
 
 1 A Mirror Pseudoscope and the Limit of Visible Depth, Psychological 
 Review, Vol. V., p. 632. 
 
 ^L'acuite stereoscopique, Revue P/tilosophique, ]?in\.\3.ry, 1900. 
 
CALIFORNIA PSYCHOLOGICAL LABORATORY. 433 
 
 300 times broader than the retinal image of the space-inequality 
 here perceptible. In view of this relatively wide expanse of 
 the fovea, it seems highly questionable whether the eye, in run- 
 ning up and down such a pair of lines would regularly take 
 one course when the lines exactly met and a perceptibly different 
 course when one line was displaced ^" . The eye naturally 
 moves by twitches and jerks, even when following a straight 
 line ; the breadth of the fovea is such as to permit considerable 
 roving without ' losing ' the line. So that so small a disloca- 
 tion in the objective line would probably be no incentive to an 
 exactly corresponding change in the movement of the eye. 
 And even supposing that a dislocation of *]" in one of the lines 
 did regularly tend to draw the eye by so much out of its course ; 
 how should we be able accurately to interpret so slight a varia- 
 tion of muscular action, as clearly due to an objective spatial 
 inequality, when much greater movements — likewise involun- 
 tary, are constantly occurring without our interpreting them as 
 due to a spatial variation in the object we are observing? 
 
 If, on the other hand, we pass from the muscular apparatus 
 and look to the minute elements in the retina to explain such 
 discriminations, even these seem much too gross to account for 
 the marvellous fineness of our judgment. Rows of cones in 
 the mosaic of the fovea lie apart a distance corresponding to at 
 least an angular measurement of 3o'^ To explain our power 
 to detect a spatial difference one-fourth of this, it will be neces- 
 sary to assume either that the rods and cones are not the ulti- 
 mate spatial elements in the retina, or else that the miinmum 
 visible may be considerably less than the distance between the 
 center of the adjacent sensory elements. 
 
 And, after all, it is not difficult to see how this latter might 
 well be the case. We must, however, first give up the notion 
 that the light, even when it falls upon a single cone, or row of 
 cones, affects only those elements upon which it directly falls. 
 In every case the stimulation is probably diffused in all direc- 
 tions ; a responsive wave runs through the neighboring elements, 
 as is evidenced, for instance, by the fact of simultaneous con- 
 trast. Now if C and O be adjacent elements, and b the boun- 
 dary between them, then it seems not improbable that if a ray 
 
434 
 
 GEORGE M. STRATTON. 
 
 c 
 
 Fig. 2. 
 
 fall somewhere within the limits of C its effect upon O will be 
 different according as its point of incidence is nearer or farther 
 from d. It would probably excite O more intensely the nearer 
 it fell to the limits of this cone ; and, on the other hand, its 
 
 effect upon O', a neighbor on the 
 opposite side of C, would cor- 
 respondingly decline. In such 
 an event there would be a differ- 
 ence of nervous result with every 
 change, however small, of the 
 point of incidence, instead of a 
 change occurring only in case the 
 stimulus passed to an entirely dif- 
 ferent cone. There would then 
 be a difference of intensity of the 
 diffusive effect upon neighboring elements, a different degree of 
 whatever kind of reaction may be characteristic of each, and con- 
 sequently a change of ' local sign ' even when the difference of 
 place of the excitation is considerably less than the diameter of a 
 single element. The local signs in the retina alone, quite apart 
 from the muscular mechanism, would thus form an absolutely 
 continuous series, and would furnish the data for any degree of 
 spatial discrimination we may discover. The retinal sign of posi- 
 tion is thus conceived, not often the analogy of our electric signal 
 boxes, when one unalterable mark is given (a falling numeral, 
 for example) whenever the same terminal is affected ; but we 
 should have to symbolize it rather by some more complicated 
 contrivance : where nothing less than several neighboring num- 
 bers dropped on each occasion, but each of these appeared with 
 differing clearness according as its particular terminal was near 
 or far from the immediate origin of the disturbance. The rela- 
 tion of the various intensities could in this case be a sign both 
 of direction and of distance ; and the exact seat of the exciting 
 cause be determined with a degree of accuracy depending on 
 the fineness of discrimination for intensive differences and for 
 catching their interrelation, rather than upon the number and 
 distance apart of the several terminals ; in other words, the 
 threshold would not depend on the purely anatomical meas- 
 
CALIFORNIA PSYCHOLOGICAL LABORATORY. 435 
 
 urements, if we may drop the figure and return to the retinal 
 fact. 
 
 The present experiment, then, tempts one to believe that the 
 local signs are of this exceedingly complicated character. The 
 mental process of localization, or of space-distinction, cannot 
 be justly described (it would seem) as an association merely 
 between a particular quality of sensation and a particular place. 
 Nor is it entirely sufficient to amend this and say that the mind 
 must also take account of the various intensities of the quality 
 which is spatially significant. The complication seems to go 
 still a degree higher, so that the interrelation of numberless in- 
 tensities of different retinal sensations would seem to be the 
 intricate process involved in even the simplest visual perception 
 of space. When we bear in mind that the fully organized per- 
 ception without doubt includes also extra-retinal data, it is evi- 
 dent how complex an activity our spatial consciousness is. 
 
 II. The Effect of Imperceptible Shadows on the 
 Judgment of Distance. 
 
 BY KNIGHT DUNLAP. 
 
 The conscious effect of stimulation of such low intensity 
 as to be imperceptible presents an attractive and almost unex- 
 ploited field for experimental work. The experiments of Jas- 
 trow and Pierce on small differences of sensation,^ and some 
 previous work of my own, suggested the possibility of obtain- 
 ing important results from an experiment planned to show 
 directly the effects of the presence or absence of an impercep- 
 tible stimulation. 
 
 The Miiller-Lyer figure was selected as the foundation for 
 such an experiment. If we have the segments of the principal 
 line in the illusion-figure distinctly marked, but the angular 
 lines of an intensity just below the threshold of perception, we 
 have the simple materials for determining whether or not these 
 imperceptible lines will produce in any degree the ordinary 
 illusion-effect. If such an effect is produced, then we have 
 
 1 Memoirs of the National Academy of Sciences, Vol. III., p. 76. 
 
436 
 
 KNIGHT DUN LAP. 
 
 evidence for the belief that under certain conditions things of 
 which we are not, and can not become, conscious have their im- 
 mediate effects upon consciousness. 
 
 The apparatus used in the first investigations under these 
 conditions was very simple, and not altogether satisfactory in 
 its operation, but as the experiments were of the nature of a 
 preliminary survey of the ground, it was not deemed advisable 
 to make a complicated arrangement of apparatus. 
 
 Fic 
 
 Fig. 2. 
 
 The screen upon which the illusion-figure vv^as to be shown 
 was a sheet of white bristol-board, fifty-eight centimeters by 
 seventy-two centimeters, fastened upon a frame. A black line 
 one millimeter in width (see Fig. i) was drawn across the mid- 
 dle of the screen horizontally, and divided in the center by a 
 perpendicular line three-fourths of a millimeter in width, and 
 extending eight millimeters on each side. On the sides of the 
 frame holding the screen, and on a level with the horizontal 
 line were fixed guides, in which slid small steel rods passing 
 along the line and hidden against it. Small strips of black 
 paper two millimeters wide and ten millimeters long were fas- 
 tened to the inner ends of these rods in positions parallel to the 
 central vertical line and extending equally above and below the 
 horizontal line, and these with the central vertical line marked 
 off two segments of the horizontal line. The lengths of these 
 segments could be varied at will by sliding the rods along the 
 horizontal line. 
 
 Fastened to each of these rods carrying strips, and parallel to 
 them, was another exactly similar rod passing behind the screen 
 and bearing on its inner extremity an angle of ninety degrees, 
 cut from black bristol-board, with legs five millimeters wide and 
 
CALIFORNIA PSYCHOLOGICAL LABORATORY. 437 
 
 forty-five millimeters long. These angles, together with a simi- 
 lar one fastened in the center, showed upon the front of the 
 screen as shadows when light was transmitted through from the 
 back, and transformed the segments of the line into the typical 
 Miiller-Lyer figure. The arrangement of this part of the 
 apparatus maybe understoood from Figs, i and 2, which show 
 respectively the front and back of the screen. It will be ob- 
 served that by interchanging the pairs of rods and reversing the 
 central angle the direction of the illusion could be reversed. 
 
 The screen was illuminated from the front by two hooded 
 incandescent lights placed one at each side so as not to obstruct 
 the view, and at equal distances from the screen. Behind the 
 screen w^as a single hooded incandescent light, so shielded with 
 tissue paper as to diffuse the light as evenly as possible over the 
 back of the screen. The intensity of this light, and therefore 
 the intensity of the shadows on the front of the screen, was con- 
 trolled by means of a rheostat, the front lights remaining un- 
 changed. As the current for the three lights vv^as taken from 
 the same circuit, variation in the potential affected them all in 
 approximately the same ratio, and hence the relative intensit}* 
 of the light coming through the screen to the light falling upon 
 the face of it, as determined b}^ the adjustment of the rheostat, 
 might be supposed to remain fairly constant. 
 
 The method of operation was very simple. One of two fig- 
 ures, a double square and a circle, was placed against the back 
 of the screen to test the intensity of the light, and the intensity 
 of the rear light w^as reduced until the subject was unable to de- 
 tect the shadows caused by the figure. Upon reaching a point 
 at which it was certain that the subject could not tell whether 
 the figure was circular or square, it w^as removed and the an- 
 gles of the Miiller-Lyer figure placed in position. It was de- 
 termined by the toss of a coin whether the angles should be set 
 in the ' short ' or ' long ' position,^ and the left cross-line was 
 fixed at twenty-five centimeters from the center. The right 
 
 iThe direction of the angles which tends to shorten the left or standard seg- 
 ment of the line, thus <:^ — ^ < , will, throughout, be spoken of as ' illu- 
 sion short.' The opposite direction of the angles, which tends to lengthen the 
 left segment, will be spoken of as ' illvision long.' 
 
43S KNIGHT DUN LAP. 
 
 cross-line was started from a point sufficiently greater or less 
 than twenty-five centimeters from the center to be distinctly per- 
 ceived as farther or nearer than the left one, and moved at reg- 
 ularly timed intervals^ by steps of one millimeter towards and 
 past the equality point, the judgment of the subject as to the 
 length of the right segment of the line as compared with the 
 left segment being recorded at every step in the series. 
 Whether the cross-line should move inward from a point be- 
 yond the equality point, or outward from a point inside, was 
 determined by lot, correction being made toward the close, 
 however, so as to have on the whole as many series of one kind 
 as of the other in order to offset the effect of mere direction of 
 motion. It is evident from the details given above that the angle 
 behind the right cross-line moved with it, so that the relations 
 of the Miiller-Lyer figure were constantly preserved. 
 
 Series of this kind alone would of course not be sufficient to 
 determine whether or not the illusion figure is effective. As 
 will be seen later, there is a tendency to judge the equal seg- 
 ments of a line as different even apart from any influence of the 
 angles of the Miiller-Lyer figure. Hence it was necessary for 
 purposes of comparison with these to take also series in which 
 there could be no possible illusion, since the light behind the 
 screen was entirely cut off. If there should be any effect pro- 
 duced by the shadows under the conditions previously stated, 
 a comparison of the series with those taken when the shadows 
 of the angles were present but imperceptible might show it. 
 
 The series were consequently taken in pairs or sets, each 
 pair being composed of one series with the shadows, and one 
 without, taken in immediate succession, in the same direction, 
 and from the same point. The order in which the two were 
 taken was determined for each pair by lot, as was also the direc- 
 tion of the illusion as mentioned above. The subject being ig- 
 norant of the results of the lots, there was a double check upon 
 the possibility of any influence arising from his knowledge of 
 how the illusion might be expected to affect his judgments. 
 Any general difference between the two classes of series could 
 
 iThe interval was nine seconds in length from the completion of a judgment 
 until the command to look again at the screen. 
 
CALIFORNIA PSYCHOLOGICAL LABORATORY. 
 
 439 
 
 therefore only be due to the effect of the angles behind the 
 screen. 
 
 In general, each series proceeding outward resulted in first 
 a number of judgments of ' shorter,' then one or more of 
 ' equal ' or ' doubtful,' and finally, a number of ' longer.' 
 In the series proceeding inward the order was reversed. The 
 middle point of the region of doubt and equality was taken as 
 the mean equality point of each series, and this was compared 
 with the mean equality point of the other member of the pair. 
 The region of doubt and equality was determined by fixed rules, 
 and, in order to secure absolute impartiality the point was de- 
 termined without the experimenter himself knowing to which 
 class the series belonged. For this purpose a number of the 
 records were allowed to accumulate, were shuffled, and their 
 distinctive marks concealed until their mean equality points 
 were determined and recorded. 
 
 Three subjects were employed, and the results of the work 
 with them are summed up in Table I. A set was counted ' for ' 
 or ' against ' the illusion according as the difference between 
 the mean equality points of the two series composing it was or 
 was not in the direction which would correspond to the possible 
 effect of the illusion-figure. 
 
 Table I. 
 
 Subject. 
 
 Total Pairs. 
 
 For Illusion. 
 
 Against. 
 
 Neutral. 
 
 A. 
 
 R. 
 
 S. 
 
 23 
 
 II 
 
 13 
 
 14 
 9 
 
 8 
 
 8 
 
 2 
 
 5 
 
 I 
 
 
 
 We see from this table that 60 per cent, of the sets for sub- 
 ject A. fall on the side of the illusion, 81.8 per cent, for R., 
 and 61.5 per cent, for S. The figures are rather meager, but 
 as far as they go are strongly suggestive. As the experiments 
 were designed only as preparatory to the investigation proper, 
 to point to possible results and expose the difficulties in the way, 
 the results were counted sufficient, and preparations were made 
 for more careful experiments along the same line. 
 
 The apparatus used in the later work differed materially 
 from that which was described above in the account of the pre- 
 
440 
 
 KNIGHT DUN LAP. 
 
 liminary investigation. It was desired that there should be 
 some means of measuring the relative intensities of the shadows, 
 and as this was practically impossible when they were cast by 
 light transmitted through the screen, it was decided to try the 
 effect of casting the shadows directly upon the front of the 
 screen. This of course necessitated the removal of the angles 
 used in casting the shadows to some distance from the screen, 
 in order that they might not be in the subject's line of vision, 
 and this in turn demanded the use of light radiating from a 
 very small area, that the shadows might be sharply defined. 
 The best form of illumination available for this purpose was 
 the electric arc, and as it is not possible to maintain the intensities 
 of two arc lights at anything like a constant ratio, it was nec- 
 essary to cast the shadows from the same source of light which 
 furnished the general illumination of the screen. This was 
 effected by the aid of mirrors, which diverted in opposite direc- 
 tions the light coming from the lamp, and combined it again 
 upon the screen. An automatic adjustment lamp was first tried ; 
 
 0V 
 
 Fig. 3. 
 
 but as it proved too unsteady, a hand adjustment lamp, with 
 carbons at right angles to each other, was constructed in the 
 laboratory and found more satisfactory. The arrangement of 
 the lamp with the other parts of the apparatus is shown by the 
 diagram in Fig. 3. The lamp was placed in a box having a 
 blackened interior and suitable apertures for the emission of 
 light from the front, and for ventilation. The light reflected 
 by mirrors N and M fell upon the screen P without interven- 
 
CALIFORNIA PSYCHOLOGICAL LABORATORY. 441 
 
 tion, but that reflected by N' and M' was intercepted by the 
 episkotister E^ by which any desired proportion of the light 
 was cut out. This light passed through the frame F, in which 
 were suspended on silk fibers angles measuring sixty degrees 
 (these being more favorable to the illusion effect than those of 
 ninety degrees used in the preliminary work), and cast their 
 shadows on the screen P. This screen was the one used in the 
 preliminary work, with the exxeption of the angles at the back, 
 which were superfluous in the present arrangement, and were 
 therefore removed. It was placed in a position perpendicular 
 to the line of vision of the subject at S^ who was seated at one 
 side, out of the path of the light, and hence the distribution of 
 the light on the face of the screen was slightly unsymmetrical. 
 This was unavoidable, however, on account of the dimensions 
 of the room which was selected as best adapted to the purposes of 
 the experiment. The walls, floor and ceiling of the room were 
 black, preventing any great reflection of light back to the screen. 
 
 Some difficulty was experienced with the mirrors, and those 
 of carefully selected plate-glass used in the experiment were 
 not thoroughly satisfactory. Better results could probably have 
 been obtained by the use of lenses and totally reflecting prisms. 
 
 The fibers by which the angle casting the right-hand shadow 
 was suspended were attached to slides working in the frame F^ 
 so that the angle could be moved along as the right-hand cross- 
 line was moved on the screen, thus keeping the vertex of the 
 shadow approximately on the cross-line on the screen P. The 
 principal remaining pieces of apparatus were screens, one at 
 R to prevent the subject seeing the figure at P except at the 
 proper time ; and one at T to conceal the angles in the frame 
 F 2X all times. The distance from the subject to the figure was 
 about two and a quarter meters. 
 
 It will be observed that since the two pencils of light were 
 taken from practically the same side of the glowing carbon, the 
 effective area of which was only a few millimeters in extent, 
 variations in the intensity of the light affected them both ap- 
 proximately equally as regards their initial intensities, and 
 hence did not change the relative intensities as established by 
 the episkotister. Since therefore the intensity of the light did 
 
442 KNIGHT DUN LAP. 
 
 not vary greatly, the perceptibility of the shadows should have 
 remained constant according to the general statement of 
 Weber's law. 
 
 What has been said concerning methods in the preliminar}- 
 work will, with some important exceptions, apply to the main 
 work also. The proper intensity of the shadows was deter- 
 mined for each subject by careful tests, and these were fre- 
 quently repeated during^the course of the experiment to insure 
 the correctness of the mtensity adopted. It was found that 
 subjects A., R. and W. could not detect any shadows when the 
 total angular opening in the episkotister was seven degrees. 
 For the sake of safety six degrees was used in the actual work 
 with these subjects. S. at one time seemed to perceive the 
 shadows with an aperture of seven degrees, and therefore five 
 degrees was fixed upon as entirely safe for him. These pro- 
 portions are rather large as compared with the figures usually 
 given for the difference-threshold of light, but it should be re- 
 membered that the shadows were not perfectly distinct, on ac- 
 count of the effect of the fringe of luminosity surrounding the 
 effective portion of the positive carbon, and also on account of 
 multiple reflection in the mirrors. 
 
 As it took some time to change the direction of the angles in 
 the frame, they were placed at the beginning of each experi- 
 ment-period in the direction determined by lot, and continued 
 in the same direction during the whole period (three-quarters of 
 an hour), unless (as happened some few times) the subject ac- 
 cidentally became aware of the direction of the angles. In 
 such a case a coin was tossed to determine whether or not the 
 angles should be reversed, the subject being ignorant of the 
 outcome of the lot, and so not knowing whether the shadows 
 were continued in the position in which he saw them, or were 
 reversed, or were entirely removed and a shadowless series 
 commenced. Towards the end of the work the angles were 
 arbitrarily placed so as to have an equal number of series for 
 each of the two directions of the illusion. To economize time, 
 the angle which cast the right shadow was not moved each time 
 the corresponding cross-line was moved, but only every fifth 
 time, the width of the shadow allowing that amount of move- 
 ment without complete disconnection. 
 
CALIFORNIA PSYCHOLOGICAL LABORATORY. 
 
 443 
 
 No attempt was made to run series in both directions, as it 
 was not indispensable for the comparison of the series, and 
 there were enough complications without this additional factor. 
 All the series were run outward from a point nearer to the cen- 
 ter than the standard length of twenty-five centimeters. 
 
 When the shadows were removed, in the shadowless series, 
 by cutting off the light normally reflected by mirrors M' and N' , 
 the episkotister was kept running, and the angle was moved in 
 the frame at the usual times in these series as in the others, so 
 that the subject had no clue as to whether or not the shadows 
 were present in any series. 
 
 For fear lest the imperfections in the mirrors might produce 
 irregular distribution of the light on the screen in such a way 
 as to affect the results of the series, the two mirrors on one side 
 were interchanged from time to time with those on the other 
 side, and an equal number of series taken in each of the two 
 positions. There were thus three conditions to be equalized, 
 viz : (i) Position of the mirrors ; (2) Direction of the illusion ; 
 (3) Order of series in the set, /. ^., whether the series with the 
 shadows was given first, immediately succeeded by the series 
 without the shadows, or vice versa; in the scheme which fol- 
 lows the first class are called ' shadows first ' and the second 
 ' shadows last.' 
 
 This classification broke the sets of series up into eight 
 groups, which were kept equal in the long run (with one ex- 
 ception, to be mentioned later), although the sets into which 
 the series fell were determined by lot from day to day as far as 
 possible. These groups are given schematically in the follow- 
 ing table : 
 
 1st position of mirrors. 
 
 2d position of mirrors. 
 
 Illusion long. 
 
 Illusion short. 
 
 Illusion long. 
 
 Illusion short. 
 
 Shadows first. 
 Shadows last. 
 Shadows first. 
 Shadows last. 
 Shadows first. 
 Shadows last. 
 Shadows first. 
 Shadows last. 
 
444 KNIGHT DUN LAP. 
 
 On account of the complication of the apparatus and the 
 difficuhies of its operation, the progress of the experiment was 
 necessarily slow. No attempt was made to have the subject 
 judge at regularly timed intervals. An endeavor was made, 
 however, to give all series with the same approximate rapidity, 
 and the rate of ten minutes to a set was pretty constantly main- 
 tained. This allowed the taking of three sets or pairs in a 
 period of forty-five minutes, if all worked smoothly, the rest 
 of the time being consumed in the necessary adjustments of the 
 apparatus. Very frequently, however, troublesome delays oc- 
 curred, which reduced the number of sets to two or one. 
 
 Each subject was instructed to preserve a fixed method of 
 bringing his eyes upon the line. One preferred to bring his 
 eyes upward from the floor to the middle of the line after remov- 
 ing the swinging screen, while the others preferred to gaze at 
 the swinging screen, in the direction of the center of the line, 
 and then displace it. This regularity was insisted upon because 
 it was found by actual trial that the direction in which the eyes 
 were brought upon the screen influenced the proportional esti- 
 mate of the segments of the line. Therefore a difference in this 
 respect between the different series might introduce a difference 
 in the results which would confuse the interpretation. 
 
 The subject was not however compelled to maintain his gaze 
 fixed upon the central point, but moved his eyes over the line 
 as he pleased in forming his judgment. In the extreme cases 
 the disparity of the segments of the line was perceived by 
 glancing at the center, but where the difference was very slight 
 the subject gazed at one segment until he had its length well 
 in mind and then transferred his regard to the other segment in 
 order to make comparison. 
 
 It is probable, however, that the steady fixation of the seg- 
 ments was on the whole a bad practice, as it rendered possible 
 the formation of an after-image of the first segment by which 
 the second segment might be judged by mere superposition, which 
 would be in a large measure destructive of the effect of the il- 
 lusion, if there were any such effect. The difficulties of judg- 
 ing were however so great that it was not deemed advisable to 
 place any additional restrictions on the subject. 
 
CALIFORNIA PSYCHOLOGICAL LABORATORY. 445 
 
 The experiment would naturally have been much simplified 
 if the shadowless series had been omitted, and the sets of two 
 made to consist of one with the illusion short and one with it 
 long. This would have reduced the number of groups to four, 
 and would perhaps have nearly doubled the difference between 
 the series on each set, but it was deemed inadvisable for several 
 reasons. First, the changing of the direction of the angles for 
 each series would have consumed so much time that the gain by 
 omitting the shadowless series would have been largely offset. 
 Second, the data for the judgments of the segments of the line 
 with the influence of the illusion excluded are important in 
 themselves. And third, it was considered possible that under 
 the conditions, the illusion, if effective at all, might be more 
 effective in one position or direction than in the other ; a state 
 of affairs of which the proposed method would offer no evi- 
 dence, should it actually exist. The results as set forth later 
 justif}^ the procedure actually adopted, although additional ex- 
 periments ought to be made in the proposed manner to supple- 
 ment the results of these. 
 
 One more point as to the methods, and then we may pass on 
 to the next division of the subject. The series were always 
 commenced far enough inside of the actual equality-point to 
 give a distinct impression of shortness to the right segment of 
 the line. They were not however commenced uniformly at the 
 same point, but were varied irregularly^ in this respect from set 
 to set, and the subject was given to understand that they were 
 irregular, lest the distribution of his judgments in one series 
 should influence him in the next. Both of the two series of 
 each set were of course commenced at the same point, so that 
 any possible effect of the length of the series, or the strength 
 of the contrast with which the series began, might affect them 
 both alike ; but this was not mentioned to the subject, who con- 
 sequently never knew whether a given series began at the same 
 point as the preceding. It is interesting to note that the gen- 
 eral region of commencing the series was necessarily varied 
 from day to day and even from set to set on account of the 
 varying relative estimation of the segments of the line. Thus 
 a point which one day was well within the range of judgments 
 
446 
 
 KNIGHT DUN LAP. 
 
 of ' short ' might be the next day within the range of judgments 
 of ' equal.' This will be further exemplified later in the 
 discussion. 
 
 Four subjects were employed, three of whom, S., R. and A., 
 had taken part in the preliminary work. In the cases of S. and 
 R. eighty series (forty sets) were taken from each, evenly dis- 
 tributed according to the scheme of the eight classes of sets al- 
 ready specified ; but in the case of A. only sixty-four series 
 (thirty-two sets) evenly distributed, and in the case of the other 
 subject, W., seventy-two series (thirty-six sets, twenty under 
 the class 'long' and sixteen under the class ' short') were ob- 
 tained. 
 
 The most obvious method of comparison of the series was 
 by sets, taken in the same manner as that in which the series 
 in the preliminary work were compared. The same precautions 
 for impartiality in computation were observed here also. The 
 results of this comparison as given in Table II. are far more 
 striking than the results for the preliminary work. 
 
 Table II. 
 
 Subject. 
 
 Total Sets. 
 
 For. 
 
 Against. 
 
 Neutral. 
 
 S. 
 
 40 
 
 23 
 
 15 
 
 2 
 
 W. 
 
 36 
 
 19 
 
 II 
 
 6 
 
 R. 
 
 40 
 
 25 
 
 9 
 
 6 
 
 A. 
 
 32 
 
 23 
 
 7 
 
 3 
 
 Expressed in percentages this table becomes Table III., as 
 
 follows : 
 
 Table III. 
 
 Subject. 
 
 f» for. 
 
 f against. 
 
 f neutral. 
 
 s. 
 
 57-5 
 
 37-5 
 
 5-0 
 
 w. 
 
 52.8 
 
 30.5 
 
 16.7 
 
 R. 
 
 62.5 
 
 22.5 
 
 15.0 
 
 A. 
 
 68.8 
 
 21.9 
 
 9-3 
 
 This shows a preponderance for the illusion ; twenty per 
 cent, for S., over thirty-two per cent, for W., forty per cent, 
 for R. and over forty-six per cent, for A. Or, if we leave out 
 of account the neutral cases and give directly the ratio of favor- 
 able to unfavorable cases, we find the following values : S., 1.5. 
 
CALIFORNIA PSYCHOLOGICAL LABORATORY. 447 
 
 W., 1.7; R., 2.8, and A., 3.1, which are certainl}^ too large 
 and agree too well to be set down as the result of mere chance. 
 A second comparison naturally suggested would be between 
 the average of the mean equality-points for the shadowless series 
 and the averages for the series with the illusion-figure in both 
 positions. An examination of the series, however, showed that 
 the average for all of the shadowless series could not be fairly 
 compared with the averages for each of the other two classes, 
 since the series for the two latter occurred in groups irregularly 
 distributed throughout the time the experiment was continued, 
 and the general position of the mean equality-point varied 
 greatly during the progress of the work. 
 
 XN / 
 
 / s 10 is zo zs 30 3s; 
 
 Fig. 4. 
 
 This is illustrated by Fig. 4, which gives the position of the 
 mean apparent equality-points for each of the shadowless series 
 of experiments with subject W. In this diagram the values of 
 the abscissa represent the order of the series in the course of the 
 experiment, while the ordinates give the difference in millimeters 
 between the standard line and that length of the variable which 
 seemed equal to it. Positive ordinates, therefore, show that the 
 apparently equal variable was actually longer than the standard, 
 while negative ordinates indicate that it was shorter. 
 
 All of the graphs thus obtained were ver}' irregular, and those 
 for subjects W., R. and A. show a decided upward tendency 
 from first to last, indicating that while early in the experiment 
 the right segment was proportionately overestimated, later it 
 
+fS 
 
 KNIGHT DUNLAP. 
 
 was underestimated. Subject S., with a single exception, over- 
 estimated the right segment throughout the experiment, rather 
 more toward the last than the rirst. 
 
 The graphs must not be understood as analogous to the filling 
 in of the points of a probable curve between known points, as in 
 this case the points represent discrete series and there are no 
 possible points which might be computed between them. Only 
 the known points are significant therefore, the lines joining 
 them having been added to distinguish the trend of the series 
 and make it more easily comprehended by the eye. 
 
 The ordinates for the series with shadows would correspond 
 pretty closely with the ordinates for the shadowless series with 
 which they belong ; but, as previously noted, the two classes of 
 series with shadows were not distributed regularly over the in- 
 terval covered by the shadowless series. In the case of one of 
 the subjects, for example, the fall of the lots was such that most 
 of the series with illusion ' long ' occurred at the upper position 
 of the graph for the shadowless series, and those with illusion 
 ' short ' at the lower positions. 
 
 It would, therefore, be manifestly incorrect to compare series 
 corresponding to the upper part of the graph with series corre- 
 sponding to both upper and lower parts, as this would bring in 
 a difference due merely to the progress of the experiment. 
 
 Table IV. 
 
 AVERAGE MEAN EQUALITY POINTS. 
 
 Subject. 
 
 S. 
 W. 
 R. 
 A. 
 
 Illusion Long. 
 
 Diflf. 
 
 Shadowless. 
 
 Shadow. 
 
 — 6.42 
 
 +2-37 
 —3-57 
 —0.37 
 
 -5-8 
 
 +2.77 
 
 —3-40 
 +0.46 
 
 + .62 
 + •40 
 
 + ■17 
 + .83 
 
 Illusion Short. 
 
 Shadowless. 
 
 —5-. 57 
 +2.65 
 — 2.40 
 +1.06 
 
 Shadow. 
 
 —5-75 
 + 1-75 
 —3-45 
 +0.78 
 
 Diflf. 
 
 - .18 
 
 - .10 
 -1.05 
 
 Hence in computing the averages, those for the shadowless 
 series which were taken at the same time as the series with the 
 illusion ' long ' were kept separate from the averages for the 
 shadowless series taken at the same time as the series in which 
 the illusion was ' short.' In other words, the averages for the 
 two classes of pairs, as distinguished by the direction of the 
 
CALIFORNIA PSYCHOLOGICAL LABORATORY. 
 
 449 
 
 illusion, were taken independently. The results for this opera- 
 tion are given in Table IV. 
 
 The figures in the first, second, fourth and fifth columns of 
 this table represent the distance in millimeters from the actual 
 
 Fig. 7. 
 
 Fig. 8. 
 
 equality point to the average mean equality point for each group 
 of series as indicated by the column headings. Negative dis- 
 tances are measured from the actual equality point towards the 
 center of the line in the illusion-figure, and positive distances in 
 
45 o KNIGHT DUNLAP. 
 
 the opposite direction. The figures in the third and sixth col- 
 umns give the differences of the averages, and hence directly 
 the average change in length of the right segment when the 
 imperceptible shadows were present. 
 
 It will be seen from Table IV. that in every case the average 
 mean equality point for the series with shadows is farther out 
 than that for the shadowless series when the illusion is ' long,' 
 and just the reverse when the illusion is ' short ' ; which is ex- 
 actly what might be expected if the illusion were really opera- 
 tive. This unanimity is certainly strongly in favor of the theory 
 that the imperceptible shadows actually affect the judgment. 
 The difference here, as in the other comparisons, is slight, but 
 we should hardly expect to get more than a slight effect from 
 the shadows under the circumstances. 
 
 This method of comparison by means of equality points nec- 
 essarily leaves out of account certain scattering judgments which 
 are bound to occur from time to time, and which are ignored by 
 the fixed rules under which the mean equality point was deter- 
 mined in each- series. We must, therefore, have some other 
 method of comparison which shall take these into account, al- 
 though their importance is not so great as is that of the more 
 regularly occurring judgments. The sporadic judgment, contra- 
 dicted by those which immediately precede and follow it, is of 
 course largely due to a sudden subjective change in the obser- 
 ver, but its significance lies in the fact that the objective condi- 
 tions might allow these subjective conditions to be more effec- 
 tive in one case than in another. 
 
 The method adopted for doing justice to these scattering 
 judgments was the comparison of the total number of judgments 
 of each kind {i. e., ' longer,' ' shorter,' and ' equal ' or ' doubt- 
 ful ') for each value of the variable lines on the screen, for each 
 of the two classes of series with the illusion shadows, with the 
 corresponding classes without the shadows. Thus, for example, 
 the totals of the different kinds of judgments when the variable 
 was 23.5 cm. (the standard being 25 cm.), when the illusion 
 was ' long,' were compared with the totals for the same point 
 in the corresponding shadowless series ; and so for all of the 
 other lengths of the variable which were used in the experiment. 
 
CALIFORNIA PSYCHOLOGICAL LABORATORY. 
 
 451 
 
 Here as before, the precaution was taken to compare each of 
 the two classes of series in which the shadows were present 
 only with the shadowless series taken in the same sets. 
 
 There being three kinds of judgments, viz., 'longer,' 
 
 Fig. II. 
 
 Fig. 12. 
 
 ' shorter ' and ' equal ' or ' doubtful,' there were then for each 
 class three totals for each point in the scale. As each of these 
 totals is significant only in so far as account is taken of the dis- 
 tribution of the remaining judgments between the two remain- 
 
452 KNIGHT DUN LAP. 
 
 ing totals, no direct comparison of the total judgments ' longer,' 
 e. g., in the shadowless series, with similar judgments in the 
 opposite series could be made with advantage. Accordingly 
 the judgments of ' short ' were taken as negative, the judg- 
 ments of ' long ' as positive, and the judgments of * equal ' or 
 ' doubtful ' as zero. The algebraic sum of these judgments 
 then, at a single point on the scale when the shadows were 
 present, or, on the other hand, when they were absent, fairly 
 represents the character of the total of the judgments at that 
 point. As the series were always begvm well wathin the region 
 of apparent ' shortness ' and ended well outside of the region of 
 equality, it was assumed that it was possible to supply judg- 
 ments at either end of those series that did not reach the limits 
 of the extent of the scale taken for comparison, thus keeping 
 equal the total number of judgments throughout the scale. 
 
 Figs. 5 to 12 give in a graphic form the results of this com- 
 parison. The abscissas represent the different lengths of the 
 variable line expressed as distances in millimeters from the 
 point where standard and variable were equal ; negative values, 
 of course, representing a variable shorter than the standard, 
 and positive a longer. Hence the values here given, plus 
 twenty-five centimeters, show the actual length of the variable. 
 The ordinates represent the algebraic sum of positive, negative 
 and zero judgments. The continuous line gives the value for 
 shadowless series, the dotted line that for series with shadows — 
 in Figs. 5 to 8 so placed as to give the illusion ' short' ; in Figs. 
 9 to 12 ' long.' 
 
 When treated in this way the results are less striking than in 
 the case of the tables of general averages. If an effect of im- 
 perceptible shadows were to appear in the graphs, it would in 
 Figs. 5 to 8 be evidenced by the fact that the ordinates of 
 points on the dotted lines would incline more toward positive 
 values than the corresponding ordinates of the continuous lines ; 
 and more toward negative values in Figs. 8 to 12. This would 
 bring the dotted line to the left of the continuous line in the 
 first group of figures, and to the right in the second group. In 
 some of the actual curves, however, the dotted line shows no de- 
 cided tendency either way (Figs. 5, 8 and 9). In Figs. 6, 10 and 
 
CALIFORNIA PSYCHOLOGICAL LABORATORY. 453 
 
 II the relation is faintly in accord with what we should expect 
 if the shadows were effective ; while in 7 and 12 the agreement 
 is quite striking. If this accord were a mere matter of chance, 
 several of the curves ought to be not simply neutral, but posi- 
 tively opposed to this course. None of the graphs, however, 
 has this character. So that, on the whole, this third mode of 
 treating the results also is favorable to the view that the shadows 
 were operative in determining the judgment. 
 
 We may now sum up the results of our investigation. We 
 have found three main points. First, when we compare the 
 series set by set as they were taken, we find that for each sub- 
 ject the large majority of the sets compare as they should if 
 the illusion were operative. Second, we find that the averages 
 of the sets compare without exception as they should under the 
 foregoing hypothesis, a result which does not necessarily follow 
 from the foregoing result. Third, we find that the totals of 
 the judgments at the various points on the scale are, to a re- 
 markable extent, in conformity with the same hypothesis. 
 These three methods of comparison cover every relation of the 
 series which can fairly demand attention, and hence may be 
 taken as exhaustive of the results of the present experiment. 
 
 A question of such importance as that with which the present 
 discussion deals requires, however, the maximum of careful in- 
 vestigation before we dare call it settled. The results detailed 
 above strongly suggest that the imperceptible illusion-figure is ac- 
 tive in producing psychical results, but for the sake of conclusive- 
 ness additional experiments should be carried out so as to permit 
 the comparison of series in which the shadows are in one posi- 
 tion directly with other series in which the shadows are in the 
 opposite position, using a modification of the method of right 
 and wrong cases, consisting in plotting the error curve for the 
 progressive intensities of the shadows by the method of Least 
 Squares, and then comparing this with the empirical results 
 obtained by the actual trial of the different intensities. This 
 method of procedure is not absolutely necessary, but is advis- 
 able on account of the added satisfaction derived from ap- 
 proaching the same problem by diverse methods. 
 
 'Hio^ejoqin |i!3!!o|oi)3^ 
 
 B|Ujoji|ea JO \spm 
 
V 
 
REPPvINTED FROM 
 
 VOL IX. No. 5. September, 1902. 
 
 THE 
 
 Psychological Review 
 
 EDITED BY 
 
 J. McKEEN CATTELL J. MARK BALDWIN 
 
 Columbia Universitt Princeton University 
 
 with the co-operation of 
 ALFRED BINET, ficoLE DES HAOTES-fiTUDES, Paris; JOHN DEWEY, H. H. DONALD- 
 SON, University of Chicago; G. S. FULLERTON, University of Pennsylvania; 
 G. H. HOWISON, University of California; JOSEPH JASTROW, Uni- 
 versity OF Wisconsin; G. T. LADD, Yale University; HUGO 
 MONSTERBERG, Harvard University; M. ALLEN STARR, 
 College OF Physicians AND Surgeons, New York; CARL 
 STUMPF, University, Berun; JAMES SULLY, 
 University College, London. 
 
 H. C. WARREN, Princeton University, Associate Editor and Business Manager. 
 
 STUDIES FROM THE PSYCHOLOGICAL LABORATORY 
 OF THE UNIVERSITY OF CALIFORNIA. 
 
 COMMUNICATED BY PROFESSOR GEORGE M. STRATTON. 
 
 III. Visible Motion and the Space Threshold. 
 BY PROFESSOR GEORGE M. STRATTON. 
 
 V. The Effect of Subdivisions on the Visual Estimate of Time. 
 BY MABEL LORENA NELSON. 
 
 PUBHSHRD BI-MONTHLY BY 
 
 THE MACMILLAN COMPANY, 
 
 41 N. QUEEN ST., LANCASTER, PA. 
 
 66 FIFTH AVENUE, NEW YORK. 
 
 Agent: G. E. STECHERT, London (2 Star Yard, Carey St., W. C) 
 
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[Reprinted from The Psychological Review, Vol. IX., No. 5, Sept., 1902.] 
 
 STUDIES FROM THE PSYCHOLOGICAL LABORA^ 
 
 TORY OF THE UNIVERSITY OF 
 
 CALIFORNIA. 
 
 COMMUNICATED BY PROFESSOR GEORGE M. STRATTON. 
 
 III. Visible Motion and the Space Threshold. 
 
 BY PROFESSOR GEORGE M. STRATTON. 
 
 For some time it has been argued that the perception of 
 motion has no immediate connection with the discrimination of 
 positions in space. It is held that the two processes are psy- 
 chologically independent, and that we become aware of motion 
 by a direct and simple sense of the motion itself, and not by 
 appreciating that the object occupies distinct localities. 
 
 This paradox is supported in part by the fact that a move- 
 ment in the out-lying portions of the visual field can be readily 
 seen when the movement has a far less extent than is required 
 to give to two motionless objects a perceptible difference of posi- 
 tion, — a fact apparently first observed by Exner. To state the 
 matter in the words of Professor James : " One's fingers when 
 cast upon the peripheral portions of the retina cannot be 
 counted — that is to say, the five retinal tracts which they occupy 
 are not distinctly apprehended by the mind as five separate 
 positions in space — and yet the slightest movement of the fingers 
 is most vividly perceived as movement and nothing else. It is 
 thus certain that our sense of movement, being so much more 
 delicate than our sense of position, cannot possibly be derived 
 from it. * * * Movement is a primitive form of sensibility."^ 
 
 1 ' Principles of Psychology,' II., 172. 
 
 433 
 
 Onhefsit) of California 
 
 Psyctiological Laboratoni. 
 
434 GEORGE M. STRATTON. 
 
 One may rightly have some antecedent hesitancy, I believe, 
 in regard to James' interpretation. Even admitting the facts he 
 offers, one need by no means draw his conclusion. For the 
 alleged sense of motion, if it really is a sense of motion^ brings 
 in a spatial report. The changes of which it makes us aware 
 are preceptibly different from alterations merely of intensity or 
 of color. Even though we may be unable to tell the direction 
 of the motion, the motion itself is a change of position, and is 
 dimly appreciated as such. Instead of saying, then, that the 
 experiments cited are evidence that the sense of movement is so 
 much more delicate than the sense of position, it would be more 
 exact to say that they show that the discrimination of positions 
 during movement is much finer than the discrimination of posi- 
 tions at rest. It is not really an antithesis between ' motion ' 
 and ' differences of position,' but between differences of position 
 under two contrasting sets of conditions, motion being but a 
 special mode of testing our power of local discrimination. The 
 truth seems to be that there are various ways of measuring this 
 power — among others, by the simultaneous presentation of two 
 lights in different places, by their successive presentation, or by 
 a continuous movement of a single light from one position to 
 another. We have no right to assume (as Professor James 
 seems to do) that the first of these methods is the only one that 
 gives the true space-threshold, and that the results of the third, 
 if finer, are indications of a process different in kind. The 
 second method also gives finer results than the first, and yet no 
 one, so far as I know, has thought that the finer space results ob- 
 tained by successive stimulation implied some special and primi- 
 tive form of sensibility different from that which is involved in 
 discriminating simultaneous impressions. Why, then, should 
 we jump to this conclusion when the conditions of space-per- 
 ception are only slightly altered farther, making the successive 
 stimulation spatially continuous instead of discrete? 
 
 Admitting the facts adduced, then it by no means follows that 
 we have a primitive sense of movement, independent of spatial 
 discrimination. But at least so far as space is concerned, the 
 facts themselves are not unquestionable. Some experiments 
 
VISIBLE MOTION AND SPACE THRESHOLD. 435 
 
 by Stern, reported in 1894/ already raised a doubt here. Stern 
 found that when retinal irradiation was decidedly reduced, the 
 shortest perceptible movement was not appreciably less than the 
 space-threshold as determined without movement. He conse- 
 quently inferred that there was no ground for assuming a 
 specific and unique sense of movement. But the test of motion- 
 less space-discrimination used by Stern is itself perhaps not 
 fully convincing. He departed from the method employed by 
 Helmholtz and others — the method by parallel lines brought 
 closer and closer together until they almost fused — and, 
 instead, took as the threshold that width of a single dark 
 line that was just doubtfully perceptible against a light back- 
 ground. The assumption here seems to be that the line is a gap 
 or interruption of the white surface, and implies a local dis- 
 crimination of the two borders of white against the line which 
 divides them. But if we regard black as a positive impression, 
 as it would seem we must, there would appear to be no reason 
 why a consistent development of this method would not require 
 us to accept the apparent diameter of a just perceptible fixed 
 star as a still more accurate measure of local discrimination. 
 The width of the dark line in Stern's experiments is probably 
 of importance only in a secondary way, by affecting the inten- 
 sity of the impression of black. This suspicion is strengthened 
 by the fact that with some slight improvements in the conditions 
 of observation in our laboratory, while still remaining true to 
 the general principle of Stern's method, the threshold takes an 
 astonishing drop. One of my students, Mr. Gilbertson, finds 
 that the width of the black line visible against white, instead of 
 being 15" angular measure, as Stern found under his condi- 
 tions, may be even less than 2.5". 
 
 For this reason it seemed well to try some experiments in 
 which the threshold of motion and that of local discrimination 
 might be compared without so much doubt as to the really 
 spatial character of this local discrimination. The experi- 
 ments here reported fall into two groups, the first with indirect, 
 the second with foveal vision. 
 
 ^Die Wahrnehmung von Bewegungen vermittelst des Auges, Zeitsch. f. 
 Psychol, u. Physiol, d. Sinnesorg., VII., 321. 
 
43^ GEORGE M. STRATTON. 
 
 t f 
 
 Fig. I. 
 
 I. Experiments with Indirect Vision. — The observer, in 
 Fig. I, sat in a half-darkened room and judged the character of 
 the light-stimulus seen through a narrow vertical slit / about ^ 
 mm. wide in a screen ^S" before him. The fixation pointy was 
 5° to the right of the slit in one set of experiments and 30° to 
 the right in the other, the distance from the observer to the 
 screen being in these two cases 2 m. and i m., respectively. 
 When the aim was to determine the threshold of motion, a 
 bright point of light moved from a fixed position upward or 
 downward in the slit, while the local discrimination was tested 
 by two separate motionless points of light which appeared the 
 one above the other and in immediate succession. The extent 
 of movement, in the one case, and of spatial separation in the 
 other, were of course accurately varied to determine the 
 threshold. 
 
 This variation, along with a constancy of those conditions 
 that should remain constant, was brought about by an arrange- 
 ment behind the screen, consistmg chiefly of a pendulum Z' carry- 
 ing a smaller slitted screen S' ^ which in swinging past the slit 
 / allowed light to pass to the observer from a white surface w 
 evenly illuminated by an electric lamp, L. The pendulum was 
 so controlled by the electromagnets e and e' as to give a single 
 swing from a fixed point 10° from the vertical and be caught at 
 the end of its course on the other side. The back-swing in 
 preparation for the next experiment was concealed from the 
 observer. The length of the pendulum was regulated to give 
 a single oscillation in one second. 
 
 In Fig. 2 there is represented in diagram the screen S' that 
 was carried by the pendulum when the aim was to give the 
 observer a moving point of light. The main feature of this 
 
VISIBLE MOTION AND SPACE THRESHOLD. 
 
 437 
 
 screen was a movable circular disc Z>, from whose center, c^ 
 there passed to the periphery a slit c^, ^ mm. in width, forming 
 an arc of the circle whose radius was the distance from C to 
 the point of suspension of the pendulum (70 cm.). When the 
 
 Fig. 2. 
 
 disc was so set that the center of this arc coincided with the 
 point of suspension of the pendulum, the point of light which 
 came to the observer as this arc-slit swung past the vertical slit 
 / in the stationary screen S in Fig. i had no apparent motion 
 whatever. A change of the disc's position, however, so that 
 the slit took the position r^', would cause an apparent upward 
 motion of the point of light, the extent of which in angular 
 measure, from the point of view of the observer, could readily 
 be calculated. A scale in terms of such angular measurement 
 was placed along the circumference of the disc so that this 
 could be set for any extent of motion desired. But since it 
 seemed best to keep the duration of the movement exactly the 
 same as the duration of the stimulus in the corresponding set of 
 experiments with motionless points, this constancy, in spite of 
 the varying positions of the disc, was maintained by the fact 
 that the screen S' was continuous behind the disc D with the 
 exception of an opening klmn, whose boundaries kl and 7nn 
 were radii of the circle mentioned above, the center of which 
 was the point of suspension of the pendulum. It need only be 
 added that, this screen was wide enough to conceal the surface 
 w in Fig. I, when the pendulum was at either limit of its ex- 
 cursion. 
 
43S 
 
 GEORGE M. STRATTON. 
 
 For the experiments on the discrimination of position with- 
 out movement, a different screen was substituted upon the 
 pendulum, yet with a similar arc-slit similarly centered. But 
 in this case, instead of revolving the slit about a central point, 
 one half of the slit could be shifted slightly up or down, along 
 the radius of the circle of which the arc was a portion, as in 
 
 S' 
 
 Fig. 3. 
 
 Fig. 3. As the pendulum made its single swing, there thus 
 appeared to the observer in immediate succession two separate 
 points of light, the amount of whose separation could be accu- 
 rately varied by the experimenter. 
 
 In the preliminary experiments, the well-known method of 
 * minimal changes ' was employed, but the observers soon 
 showed themselves so much influenced by expectation that no 
 reliable determination of the thresholds seemed possible by this 
 means. The method of ' serial groups,' hereinafter described, 
 was found more satisfactory. The adoption of successive 
 stimuli to measure the local discrimination without movement, 
 was for the purpose of avoiding some of the worst difficulties 
 from irradiation. Two points of light when presented simul- 
 taneously will often produce a blur that is perceptibly extended 
 (and consequently spatial), and yet two separate nuclei of light 
 are not distinguished within this vague extent. According to 
 the usual method of interpreting the results, we should here be 
 below the space-threshold, although, of course, we are not. 
 What Tawney has already justly insisted on with regard to 
 
VISIBLE MOTION AND SPACE THRESHOLD. 
 
 439 
 
 tactual impressions/ that the perception of two points is not a 
 true measure of the threshold, might consequently be repeated 
 with respect to vision. The fusion of the two points is largely 
 obviated by the use of successive stimuli so that the intensity of 
 the first impression is perceptibly lessened by the time the 
 second is at its height. 
 
 But the substitution of successive for simultaneous impres- 
 sions brings what some might consider a vitiation of the results. 
 The two points of light, even when well separated, give the 
 psychological impression of continuous motion ; the light seems 
 to leap from the position of the first point to that of the second. 
 At the beginning it was thought possible to separate those 
 judgments in which an apparent motion entered, and treat them 
 as a questionable group by themselves. But when once the 
 suggestion of motion becomes fairly lodged in the observer's 
 mind, it occurs so persistently and over such a range that this 
 attempt was renounced. Since there is no objective movement 
 here, however, and the whole thing is really a matter of sug- 
 gestion pure and simple, and seems to me to imply an underly- 
 ing space-discrimination as the basis of the suggestion itself 
 (as I have urged at the beginning of this paper), the judgments 
 with subjective motion have been freely employed in computing 
 the thresholds. Those to whom these reasons do not seem suf- 
 ficient may have no such scruples over the second group of ex- 
 periments on foveal vision ; not even suggested movement there 
 enters into the judgment. 
 
 The results of the experiments with indirect vision were as 
 follows : 
 
 observer. 
 
 Angle of 
 Observation. 
 
 Number of 
 Determinations. 
 
 Discrim. of Position. 
 
 Perception of Motion. 
 
 
 Threshold. 
 
 M. v. 
 
 Threshold. 
 
 M. V. 
 
 A 
 
 Bd 
 
 Bl 
 D 
 
 5° 
 30° 
 
 5° 
 
 K 
 
 5° 
 30° 
 
 6 
 
 5 
 6 
 
 3 
 3 
 4 
 
 9.2'' 
 29.O'' 
 
 7.9' 
 18.3' 
 
 7-5' 
 63.7' 
 
 1.6' 
 
 5.2' 
 
 ■r 
 
 2.2' 
 
 3.3' 
 8.7' 
 
 10.4'' 
 29.O'' 
 
 8.3' 
 21.7' 
 
 6.6' 
 70.0' 
 
 1.4' 
 3.2' 
 1.9' 
 
 5-6' 
 
 2.2' 
 
 lo.o' 
 
 I'The Perception of Two Points Not the Space Threshold,' Psychoi,. 
 Review, II., 585. 
 
44° GEORGE M. STRATTON. 
 
 The table indicates that where the conditions are practically 
 equal, the perception of movement has no advantage over the 
 discrimination of position without objective movement. So far 
 as indirect vision is concerned, the theory that the two processes 
 are psychologically independent here finds no support. 
 
 II. Experiments with Direct Vision. — The second group 
 of experiments dealt with the same problem as the preceding, 
 ■with a change merely in the method of investigation and with a 
 different portion of the retina^the foveal instead of the excen- 
 tfic tegion of sight. On account of the extraordinary nicety of 
 our space discrimination under these conditions, the observer 
 was placed in a distant building where there was an unobstructed 
 view of one of the laboratory windows, the distance of his station 
 from the object to be observed amounting by accurate survey to 
 I20 m. The observer faced the north, and the portion of the 
 laboratory towards which he looked sent back no direct glare 
 from the sun ; preliminary experiments showed the need of 
 regarding these things. The distance of the observer's station, 
 it is true, was inconvenient in many ways, but this was more 
 than offset by the greater ease of observation. The naked eye 
 could now be employed, and all the difficulty was avoided that 
 comes from the use of a reducing lens, such as Stern found 
 necessary. The fact that the threshold of movement easily ran 
 dowh to about one half of what he reports shows the advantage 
 of these conditions. For the perception of motion a strip of 
 white bristol-board, 8 mm. wide by 50 cm. long, was mounted 
 vertically on a dead-black frame which could be moved hori- 
 zontally before a larger dead-black background. From the 
 observer's station the frame itself was invisible, aud all that one 
 saw was the white line on the large black field. The move- 
 ment of the line was controlled by runners and guides and 
 adjustable stops on the frame, so that the motion was kept hori- 
 zontal and its excursion varied by steps of i mm. The experi- 
 menter moved the frame by hand, and during any single obser- 
 vation kept the extent of the movement constant, and continued 
 the oscillations from the moment just before the exposure of the line 
 until the observer had signalled his judgment. In order to insure 
 full justice to this side of the investigation, the rate of movement 
 
VISIBLE MOTION AND SPACE THRESHOLD. 
 
 441 
 
 had, also, of course, to be taken into account; otherwise some 
 velocity might be selected that would not be the most favorable 
 to perception. For this reason the experiments on motion were 
 subdivided into five groups, with a rhythm, respectively, of 60, 
 100, 180, 300, and 450 single swings to the minute. The rates 
 were maintained with reasonable accuracy by the aid of an 
 adjustable pendulum invisible to the subject of the experiment. 
 
 For the corresponding set of experiments on the discrimi- 
 nation of position without movement the conditions were in all 
 respects the same, except that for the moving frame with its 
 single vertical line two vertical lines end-to-end against the 
 dark background were substituted. Of these two lines the lower 
 was fixed, while the upper was capable of being shifted from 
 continuity with the lower line to any position to the right or left, 
 remaining throughout parallel, however, to its original position. 
 The actual settings varied by steps of i mm., and the observer 
 had simply to judge whether the two lines at any given setting 
 Were continuous, or in what respect they spatially differed.^ 
 
 The results of the two sets of experiments under these con- 
 ditions were as follows ; 
 
 Discrimination of Position Without Movement. 
 Thresholds in mm. 
 
 Observer S. 1 
 
 Obierrer Y. 
 
 Left. 
 
 Right. 
 
 Left. 
 
 Right. 
 
 4 
 
 7 
 3 
 7 
 3 
 4 
 
 4 
 
 5 
 
 5 
 
 5 
 
 3 : 
 
 6 
 
 6 
 
 4 
 5 
 6 
 
 7 
 
 3 
 6 
 6 
 6 
 
 4 
 
 AV. 4-3 
 
 4-3 
 
 5.6 
 
 5-0 
 
 The thresholds for the discrimination of position without 
 
 movement are slightly higher than those obtained in my 
 
 previous study already referred to, but the difference is not 
 
 such as to call for any special comment. The thresholds for 
 
 the perception of movement, as affected by the rate of move- 
 
 1 For a more detailed account of this method, see my ' New Determination 
 of the Minimum Visibile and its Bearing on Localization and Binocular Depth,' 
 Psychol. Review, VII., 429. 
 
442 
 
 GEORGE M. STRATTON. 
 
 Perception of Movement. 
 Thresholds in mm. 
 
 single Oscillations per Minute. 
 
 Observer S. 
 
 Av. 
 
 II 
 
 i6 
 
 14 
 
 8 
 
 5-5 
 
 450 
 
 4-75 
 
 
 25 
 
 14 
 
 7 
 
 4 
 
 7 
 
 Observer Y. 
 
 15 
 
 14 
 
 5 
 
 6 
 
 7 
 
 
 18 
 
 8 
 
 6 
 
 6 
 
 6 
 
 
 16 
 
 12 
 
 6 
 
 5 
 
 6 
 
 Av. 
 
 18.5 
 
 12 
 
 6 
 
 5-2 
 
 6.5 
 
 ment, take a somewhat different course from those reported by 
 Stern. ^ This investigator worked with rhythms of 144, 84 and 
 72 vibrations to the second, and found merkTuilrdigerweise (as he 
 says) that the slowest movement was the one most distinctly per- 
 ceived. In my own results, it will be seen that the lower rates, 
 those of 60 and 100, are markedly unfavorable to perception, 
 with a decided improvement as we pass to 180 and 300, the 
 threshold again rising slightly as the rate is still farther in- 
 creased. Virtue here seems again to lie in the mean. The 
 lower rates require a considerable excursion before they can be 
 distinguished from rest, while the most rapid oscillations tend to 
 produce a mere indistinctness rather than a perceptible swaying 
 of the object. I am quite at a loss to account for our divergent 
 results here, unless it be that by the word ^ Schjvingtmgen,'' 
 which Professor Stern uses without modification, he means 
 ^double vibrations.' In this event his lowest rate would be 
 about midway between my 100 and 180, and he would have 
 caught only the dip of the threshold as it comes out of the region 
 where the rapidity of the impressions produces blur, without his 
 rates becoming slow enough to show the upward trend of the 
 threshold again farther on. My own subjects, like his, never 
 knew beforehand the rate that was being used, so the dis- 
 crepancy cannot be explained in this way. Possibly the differ- 
 ence is in some way connected with the fact that his observers 
 had to look through the lens of a microscope. 
 
 ^ Zeitschrift fur Psychologic u. Physiol, d. Sinnesorg ., VII., 347. 
 
VISIBLE MOTION AND SPACE THRESHOLD. 443 
 
 For observer 6*, the most favorable rates of motion give a 
 threshold of 4 mm. (about 6.8" angular measure) as against 
 4.3 mm. (about 7.3") for the discrimination of place — a net 
 advantage, for motion, of .3 mm. or .5" of arc, on the average. 
 If, however, we were to disregard averages and look at the in- 
 dividual determinations, it would appear that the space dis- 
 crimination occurred as low as 3 mm. (5.1" of arc) ; while in 
 no case does motion become perceptible below 4 mm. For ob- 
 server T^ the mean threshold for position without movement is 
 5.3 mm. (9") ; while the most favorable rate of motion gives 
 5.2 mm. (8.8") on the average. Here again the minimum 
 thresholds for position are below the smallest for movement. 
 Thus, from one point of view, motion has a slight advantage 
 over discrimination without movement, which advantage, how- 
 ever, is reversed when the numbers are differently regarded. 
 But in either case the difference is too slight to serve as a suf- 
 ficient basis for entirely differentiating the psychological pro- 
 cesses involved. 
 
 The results here, then, are in substantial agreement with 
 those obtained in indirect vision by an independent method. 
 The doctrine that visual motion is a primitive form of sensibility 
 independent of local discrimination finds no experimental war- 
 rant. The perception of motion seems to be nothing more nor 
 less than the perception that a sensation is changing its space 
 relations, the motion itself furnishing a decidedly favorable, 
 but by no means unique, set of conditions for appreciating such 
 differences of space relationship. This does not imply that the 
 detection of movement always involves a deliberate comparison 
 of positions ; for the discrimination often undoubtedly occurs 
 at a single psychic stroke. But even this apparently simple 
 stroke is really a complex act. It implies a relational activity 
 of the mind which interprets and gives character (crude and 
 confused though it be) to the incoming sensations, so that they 
 are no longer blank impressions, but are impressions which 
 mean for us movement. The experiments thus go to support 
 the view that a fact of space can never be conveyed to the mind 
 in the form of a pure sensation divested of all relationship. 
 
444 GEORGE M. STRATTON. 
 
 IV. The Method of Serial Groups. 
 
 BY PROFESSOR GEORGE M. STRATTON. 
 
 In the practical conduct of the laboratory one frequently 
 feels the shortcomings of the method of ' minimal changes.' 
 It is undoubtedly the best all-around mode of procedure yet de- 
 vised, but in certain cases where the conditions are exceptional 
 it may leave one quite itn Stick. This is especially true when 
 one is dealing with minimal impressions, where suggestion is 
 apt to find such free play ; the observer may continue to notice 
 a sensation when the stimulus has become suspiciously weak — 
 in fact when no stimulus at all is applied. Thus, with certain 
 excellent though suggestible subjects, I have found it impos- 
 sible to determine by the method of minimal changes, pure and 
 simple, the least extent of visible motion that could be per- 
 ceived as motion. The subjects persisted in seeing the light 
 move on every occasion, whether there was any actual 
 movement or not. The control of the answers, by requiring 
 that the observer shall tell correctly some additional feature of 
 the impression — tell, say, the direction of the movement, or, if 
 the experiments be on the least perceptible change of pressure, 
 tell whether the pressure becomes heavier or lighter — may in 
 some instances be helpful. But often this check will hide the 
 very facts that one wishes to ascertain — the point at which the 
 subject perceives motion and yet is uncertain of the direction, 
 or notice change of pressure without being able to say whether 
 the weight has grown greater or less. 
 
 The usual resort in this event is either to a so-called ' catch 
 experiment ' the Vextrversuch, where no stimulus at all is given, 
 or to the method of right and wrong cases. The latter, 
 making use as it does of the law of probability, not only re- 
 quires an extremely large number of observations, but there is 
 usually needed considerable preliminary and irregular experi- 
 mentation in order to discover the conditions that will give a 
 suitable proportion of right and wrong answers. The Vexir- 
 versuch^ on the other hand, has never been systematized, and 
 as it is usually introduced in an irregular fashion within the 
 
METHOD OF SERIAL GROUPS. 
 
 445 
 
 method of minimal changes, it is apt to disturb the even tenor 
 of the research, and disconcert the observer whenever he gets 
 a hint of what is being done. 
 
 In the method of serial groups here proposed, the attempt is 
 made to legitimate the ' catch ' experiment, to introduce it as a 
 continuous and regular element of the procedure, while secur- 
 ing certain advantages both of the method of minimal changes 
 and of the method of right and wrong cases. To give a con- 
 crete illustration, suppose the following groups of experiments 
 be carried out to determine the just perceptible extent of move- 
 ment by sight, under the conditions described in the second 
 part of the preceding paper : 
 
 Group I. 
 
 Group Ji. 
 
 Exp. No. 
 
 Amount of 
 Motion. 
 
 Judgment. 
 
 Exp. No. 
 
 Amount of 
 Motion. 
 
 Judgment. 
 
 I 
 2 
 
 3 
 4 
 5 
 6 
 
 7 
 8 
 
 9 
 
 ID 
 
 O 
 
 7 mm. 
 
 7 mm. 
 
 7 mm. 
 
 o 
 
 o 
 
 7 mm. 
 
 o 
 
 o 
 
 7 mm. 
 
 no motion, 
 motion. 
 
 no motion X. 
 
 <( (< 
 
 (i (( 
 
 motion, 
 no motion. 
 
 motion. 
 
 II 
 12 
 
 13 
 14 
 15 
 i6 
 
 17 
 
 i8 
 
 19 
 20 
 
 
 
 
 
 6 mm. 
 
 6 mm. 
 
 
 
 6 mm. 
 
 
 
 6 mm. 
 
 
 
 6 mm. 
 
 no motion, 
 motion. 
 
 no motion. 
 
 motion, 
 no motion. 
 
 motion, 
 slight motion X. 
 
 motion. 
 
 
 Group III. 
 
 
 Group IV. 
 
 Exp. No. 
 
 Amount of 
 Motion. 
 
 Judgment. 
 
 Exp. No. 
 
 Amount of 
 Motion. 
 
 Judgment. 
 
 21 
 
 5 mm. 
 
 no motion X. 
 
 31 
 
 4 mm. 
 
 very slight motion. 
 
 22 
 
 
 
 " " 
 
 32 
 
 
 
 no motion. 
 
 23 
 
 5 mm. 
 
 motion. 
 
 33 
 
 
 
 " «' 
 
 24 
 
 
 
 no motion. 
 
 34 
 
 
 
 very slight motion X. 
 
 25 
 
 5 mm. 
 
 " X. 
 
 35 
 
 4 mm. 
 
 no motion X. 
 
 26 
 
 
 
 IC <( 
 
 36 
 
 
 
 (1 i( 
 
 27 
 
 5 mm. 
 
 motion. 
 
 I 37 
 
 4 mm. 
 
 motion. 
 
 28 
 
 
 
 no motion. 
 
 38 
 
 4 mm. 
 
 '< 
 
 29 
 
 
 
 (< (< 
 
 39 
 
 
 
 no motion. 
 
 30 
 
 5 mm. 
 
 motion. 
 
 40 
 
 4 mm. 
 
 X. 
 
 THe X shows the errors in an)'- group, and from these the 
 threshold may be determined according to any proportion of 
 correct and incorrect answers that may be chosen. In my own 
 computations that group has been taken as giving the threshold 
 beyond which less than eight out of the ten judgments are 
 right. But a detail like this, as well as the exact number of 
 
446 GEORGE M. STRATTON. 
 
 experiments that may best form a ' group,' might well be con- 
 sidered as subject to revision in the light of farther experience, 
 and not as an essential part of the method. The essence of the 
 matter is simply that there should be groups of experiments ar- 
 ranged in a regular series, the amount of positive stimulus, as 
 one passes from group to group, being graduated according to 
 the principle of the method of minimal changes ; while within 
 the limits of any one group a constant stimulus is irregularly 
 alternated with cases where the stimulus is zero, thus uniting in 
 the single group the basal principle of the method of right and 
 wrong cases and that of the Vcxirversuch. This may seem 
 provokingly eclectic, but it is not exactly that ; the different 
 elements make an organic union, and not a mere patchwork. 
 There is simply an attempt to make systematic what experi- 
 menters have frequently found themselves compelled to do in a 
 casual and uncritical way. 
 
 One may perhaps repeat that this method is not proposed as 
 a general substitute for the classic ones in use. It is well, how- 
 ever, to multiply our tools so that the best may be selected for 
 the special work in hand. And this one has been found good 
 for certain purposes, especially where suggestion plays a prom- 
 inent role. The observer may here know from the very begin- 
 ning the general method of procedure ; he may know that zero- 
 cases are to be irregularly alternated with those of positive 
 stimulation, and his expectation is therefore less * set ' and influ- 
 ential. The zero-cases no longer come in as a kind of indig- 
 nity upon the observer, as if his word were being questioned. 
 The check here, because of its constancy, ceases to excite any 
 feeling. The procedure, moreover, has the virtue of the method 
 of minimal changes, in that the threshold is ascertained empir- 
 ically, by actually crossing it. And while the principle of right 
 and wrong cases is employed, with the powerful control which 
 that always brings, yet there is no introduction of the intricate 
 calculus of probability and a certain darkness that always shad- 
 ows its results. It is true that the application of the method of 
 serial groups is in a certain sense cumbersome, as compared 
 with the method of minimal changes, since in a given time 
 fewer determinations of the threshold can be obtained. But 
 
VISUAL ESTIMATE OF TIME. 447 
 
 with suitable rests between the ' groups,' there is no need of 
 there being greater fatigue to the observer in the one case than 
 in the other ; and while the determinations ma}^ be fewer for the 
 time expended, yet in most cases I have found that they more 
 than make up in weight what they lack in number. 
 
 V. The Effect of Subdivisions on the Visual Esti- 
 mate OF Time. 
 
 BY MABEIv LORENA NELSON. 
 
 It has been found by Dr. Ernst Meumann and others that the 
 estimate of small time-intervals is influenced by the number of 
 stimuli that fall within the interval. In the space illusion 
 of sight, a single division of the standard will cause it to be 
 underestimated, while more divisions will cause an overestima- 
 tion ; in touch, the effect of subdivisions depends on the abso- 
 lute length of the standard.^ 
 
 My object, in the following experiments, was to determine 
 the effect of single and multiple divisions of the standard on 
 times of longer duration than those investigated by Dr. Meu- 
 mann, and to discover if there existed a temporal illusion com- 
 parable to the space illusions of sight and touch. 
 
 In Dr. Meumann's investigation of time intervals, he com- 
 pares an ' empty ' time — one bounded by two impressions — 
 with times ' filled ' with either three, five, six, nine or twelve 
 impressions, inclusive of the terminal stimuli. His results ^ are, 
 that for times from one tenth of a second to about four seconds, 
 when the filled time comes first, the error in estimating is con- 
 stantly positive — while for longer times the error is negative. 
 
 This seems to indicate that the effect of the filling is posi- 
 tive for the short times, and negative for the longer. The error 
 found by Dr. Meumann is, however, not due to the filling 
 alone, but is the result of two factors. It is generally conceded 
 that even when two empty times are compared, there is a simi- 
 lar constant error, positive for short times, negative for longer. 
 
 'See the paper by Miss Alice Robertson, on '" Geometric- Optical ' Illu- 
 sions in Touch ' " to be published subsequently. 
 
 2 ' Beitrage zur Psychologie des Zeitbewusstseins,' Phil. Studien, XII. , p. 1 27. 
 
448 MABEL LORENA NELSON. 
 
 That there is a difference other than this constant error which 
 must be attributed to the filling, Dr. Meumann shows — for, in 
 those cases where the order is reversed, the empty time coming 
 first, the sign of the error is also reversed — but the quantity of 
 the error due to the filling alone he does not show, as these 
 two factors are not quantitatively separated. 
 
 The longest period chosen by Dr. Meumann was nine 
 seconds. The following experiments were taken to determine 
 what effect the filling would have on longer periods, durations 
 of several minutes. 
 
 The intervals chosen were one half, one, two, four, six and 
 ten minutes ; the filling, sensations of light. 
 
 Under each interval two sets of estimates were taken. The 
 first, where the standard and compared times were both empty 
 (marked E-E in the tables) was taken to determine the constant 
 error due to the mere sequence of the two intervals. In the 
 second set one of the times was always empty and the other 
 filled {E-F-AXidi F-E in the tables). Any difference found be- 
 tween the estimates of the two sets, for a given interval, must 
 be due to the filling. 
 
 The results as given in the tables are computed from five 
 estimates under each interval for the empty time, and five for 
 the filled. The average of the estimates is given ; the differ- 
 ence between this and the standard interval, expressed as a per 
 cent, of the standard ; and the mean variation from the average 
 estimate, expressed as a per cent, of the average. A second basis 
 of comparison is the median of the five estimates and its differ- 
 ence, as a percentage, from the standard interval. 
 
 The effect due to the filling for each interval is found by 
 subtracting the constant error, when both standard and compared 
 times are empty, from the error in estimating when one of the 
 times is filled. When the difference due to the filling in Tables 
 I. and II. has a positive sign, it must be taken to mean that the 
 filled time seemed shorter than an empty one of the same length. 
 In Tables III., IV. and V., however, the order is reversed, the 
 filled time being taken as the standard — a positive error here 
 would indicate that the filled time seemed longer than the 
 empty. 
 
VISUAL ESTIMATE OF TIME. 
 
 449 
 
 The method of taking the experiments was as follows : The 
 subject sat in a darkened room before a screen and saw through 
 an aperture in the screen, 5 mm. wide by 10 mm. in height, 
 flashes of light through a noiseless pendulum behind. A flash 
 of light marked the beginning of an empty time, a second flash 
 its end. During the filled time the subject saw a flash of light 
 every half second. There was in every experiment a pause of 
 two seconds between the closing flash of the standard and the 
 first flash of the compared time. The end of the compared time 
 was marked off by a word from the subject when a time had 
 elapsed which seemed to him equal to the standard. 
 
 In the first group of experiments the standard time was al- 
 ways empty. Two subjects were taken, D and 7?; the results 
 are found in Tables I. and II. The great difficulty my subjects 
 found, in the long intervals, in keeping their attention on the 
 length of the standard, made it necessary to give them some idea 
 of the interval to be used. Accordingly they were told whether 
 the interval would be short (one half and one minute were called 
 short), moderate (two and four minutes), or long (six and ten 
 minutes), and whether the compared time would be filled or 
 empty. This was, of course, in some respects a disadvantage, 
 as it perhaps affected the lengths of the estimates, but as my ob- 
 ject was to compare the estimates of a filled and an empty in- 
 terval of time, the results are not invalidated by this guidance, 
 as it was given alike in both sets. 
 
 In order that there might be no constant effect due to con- 
 trast, the order of using the different lengths as standards was 
 not fixed, but was determined by chance. The time occupied 
 by my work was never more than one hour at a time. 
 
 Table I. 
 Subject D. E-E. 
 
 Interval. 
 
 Av. Estimate. 
 
 D i, 
 
 M.V.ff 
 
 Median. 
 
 D5« 
 
 M.V.St 
 
 Yz min. 
 
 1 " 
 
 2 " 
 
 4 " 
 
 6 " 
 
 10 " 
 
 28.2 sees. 
 
 45.4 " 
 
 1 min. 40.6 " 
 
 2 " 58.2 " 
 4 " 56.8 " 
 7 " 21.4 " 
 
 — 6 
 
 — 24-3 
 
 — 16 
 
 — 25.7 
 
 — 17 
 
 — 26.4 
 
 27.5 
 10.7 
 12.6 
 
 30.2 
 14.7 
 31 
 
 34 sees. 
 
 44 " 
 
 1 min. 40 " 
 
 2 " 26 " 
 
 4 " 43 " 
 7 " 22 " 
 
 + 13 
 
 — 26.6 
 
 — 16.6 
 
 — 39-1 
 
 — 26.9 
 
 — 26.6 
 
 19.4 
 10.4 
 12.6 
 
 33.7 
 14.4 
 
 34-2 
 
450 
 
 MABEL LORENA NELSON. 
 
 E-F. 
 
 Yz min. 
 
 
 53.4 sees. 
 
 + 78 
 
 40.1 
 
 
 43 sees. 
 
 + 43-3 
 
 35-3 
 
 I " 
 
 I min. 
 
 18.6 " 
 
 + 31 
 
 15-4 
 
 I mm. 
 
 17 " 
 
 + 28.3 
 
 23-4 
 
 2 " 
 
 2 " 
 
 6.6 " 
 
 + 5-5 
 
 30-4 
 
 I " 
 
 55 " 
 
 — 4.1 
 
 35-1 
 
 4 " 
 
 4 " 
 
 6.8 " 
 
 + 2.8 
 
 27.1 
 
 4 " 
 
 20 " 
 
 + 8.3 
 
 27.7 
 
 6 " 
 
 6 " 
 
 7-4 " 
 
 + 2 
 
 33-5 
 
 6 " 
 
 53 " 
 
 + 14-7 
 
 27-5 
 
 IO " 
 
 7 " 
 
 1.8 " 
 
 — 29.7 
 
 18.4 
 
 7 " 
 
 26 " 
 
 -25.6 
 
 16.3 
 
 Difference due to Filling. 
 
 % min. 
 
 1 " 
 
 2 " 
 
 4 " 
 
 6 " 
 
 10 " 
 
 Average. 
 
 + 84 per cent. 
 
 + 55-3 
 
 + 21.5 
 
 + 28.5 " 
 
 + 19 
 
 - 3-3 " 
 
 Median. 
 
 + 30 per cent. 
 + 54-9 " 
 + 12.5 " 
 
 + 47-4 
 
 + 41.6 " 
 
 + I 
 
 The results as given in Table I. show that when the average 
 is taken as the basis of comparison, the effect of the filling on 
 the estimates in the case of D is very constant. In the interval 
 •of a half minute, a filled time 84 per cent, greater than the empty 
 is taken to be its equal. The effect of the filling seems to de- 
 crease as the length of the interval increases, until at ten minutes 
 it is but little or nothing. 
 
 Table II. 
 Subject R. E-E. 
 
 Interval. 
 
 Av. Estimate. 
 
 D?J 
 
 M.V. 5« 
 
 Median. 
 
 D?f 
 
 M.V. 5« 
 
 Yi min. 
 
 34.4 sees. 
 
 + 14.6 
 
 26.2 
 
 34 sees. 
 
 + 13 
 
 259 
 
 I " 
 
 I min. 12.2 " 
 
 + 20.6 
 
 23.1 
 
 I min. 13 " 
 
 + 21.6 
 
 23-5 
 
 2 " 
 
 I " 37-8 " 
 
 -18.5 
 
 12.8 
 
 I '« 39 " 
 
 — 17.5 
 
 17.4 
 
 4 " 
 
 3 " 12.8 " 
 
 — 19.6 
 
 16.3 
 
 3 " 17 " 
 
 — 17.9 
 
 14-5 
 
 6 " 
 
 3 " 50.2 " 
 
 -36 
 
 18.3 
 
 3 " II " 
 
 — 46.9 
 
 29.1 
 
 10 " 
 
 5 " 35-1 " 
 
 — 44 
 
 18 
 
 4 " 55 " 
 
 — 50.8 
 
 I5-I 
 
 E-F. 
 
 Y2 min. 
 
 
 36.2 sees. 
 
 + 20.6 
 
 33-5 
 
 
 40 sees. 
 
 + 33-3 
 
 28.5 
 
 I " 
 
 
 57.4 " 
 
 — 4-5 
 
 27-3 
 
 
 54 " 
 
 — 10 
 
 27.4 
 
 2 " 
 
 I mm. 
 
 47-4 " 
 
 — 10.5 
 
 29.8 
 
 I min. 
 
 39 " 
 
 — 17-5 
 
 30-7 
 
 4 " 
 
 2 " 
 
 56.2 " 
 
 -26.5 
 
 36.4 
 
 3 " 
 
 7 " 
 
 — 22 
 
 33-1 
 
 6 " 
 
 3 " 
 
 45 
 
 — 37-5 
 
 15-4 
 
 3 " 
 
 33 " 
 
 — 40.8 
 
 17-3 
 
 10 " 
 
 5 " 
 
 33 
 
 — 44-5 
 
 8.4 
 
 5 " 
 
 48 " 
 
 — 42 
 
 7-5 
 
 Difference due to Filling. 
 
 
 Average. 
 
 Median. 
 
 Yz min. 
 
 1 " 
 
 2 " 
 
 4 " 
 
 6 " 
 
 10 " 
 
 + 6 per cent. 
 —25.1 
 
 + 8.5 " 
 
 — 6.9 " 
 
 — 1-5 
 
 — -5 
 
 +20.3 per cent. 
 -31.6 
 
 " 
 
 — 4-1 
 + 6.1 
 + 8.8 
 
VISUAL ESTIMATE OF TIME. 
 
 451 
 
 With jR, Table II., the filled time seems shorter than the 
 empty in the intervals of one half and two minutes, but for all 
 the other times it seems longer, taking the average as the basis 
 of comparison. The error in the longest intervals is very small 
 and its sign is changed when the median is taken instead of the 
 average. 
 
 In continuing the experiments I introduced the filling into 
 the first or standard time, the compared time being always 
 empty. We should, therefore, expect a reversal of sign in the 
 effect due to the filling. I found that after the former practice 
 the subjects were able to hold their attention to the standard 
 time without any foreknowledge as to its length. In this second 
 group of experiments they were consequently ignorant of the 
 character of the interval to be used. In all other respects the 
 work was conducted exactly as before. 
 
 Table III. 
 Subject D. E-E. 
 
 Interval. 
 
 Av. Estimate. 
 
 D?^ 
 
 M.V. 5^ 
 
 Median. 
 
 m 
 
 M .v. i 
 
 Yz min. 
 
 30.8 sees. 
 
 + 2.6 
 
 21.3 
 
 28 sees. 
 
 — 6.6 
 
 21.4 
 
 I " 
 
 I min. 10.2 " 
 
 + 17 
 
 29.6 
 
 53 " 
 
 -11.6 
 
 33-3 
 
 2 " 
 
 2 " 25 " 
 
 + 20.8 
 
 16.6 
 
 2 mins. 10 " 
 
 + 8.3 
 
 10 
 
 4 •• 
 
 3 " 31.6 " 
 
 — II.4 
 
 21.2 
 
 2 " 47 " 
 
 — 34.1 
 
 18.9 
 
 6 " 
 
 4 " 58.9 " 
 
 — 16.9 
 
 17.6 
 
 4 " 50 " 
 
 — 19.4 
 
 13-4 
 
 10 " 
 
 9 " 31.4 " 
 
 — 4.7 
 
 23.8 
 
 10 " 40 " 
 
 + 6.6 
 
 22.2 
 
 F-E. 
 
 Yz min. 
 
 35.1 sees. 
 
 + 17 
 
 15.8 
 
 
 33 sees. 
 
 + 10 
 
 13.6 
 
 I " 
 
 55.4 " 
 
 - 7-6 
 
 29 
 
 
 46 " 
 
 — 26.6 
 
 26.5 
 
 2 " 
 
 I min. 26.6 " 
 
 -27.8 
 
 26.7 
 
 I mm. 
 
 14 " 
 
 -38.3 
 
 22.1 
 
 4 " 
 
 3 " 53 
 
 — 2.9 
 
 18.9 
 
 4 " 
 
 19 " 
 
 + 7.9 
 
 15.9 
 
 6 " 
 
 4 " 43.6 " 
 
 — 18.4 
 
 20.1 
 
 4 " 
 
 22 " 
 
 — 27.2 
 
 18.2 
 
 10 " 
 
 9 " 28.2 " 
 
 — 5-3 
 
 21.7 
 
 10 " 
 
 I " 
 
 
 
 19-5 
 
 Difference due to Filling. 
 
 
 Average. 
 
 Median. 
 
 Yz tnin. 
 
 1 " 
 
 2 " 
 
 4 " 
 
 6 " 
 
 10 " 
 
 + 14.4 per cent. 
 
 — 24.6 " 
 
 — 48.6 
 + 8.5 
 
 — 1-5 
 
 — .6 
 
 + 16.6 per cent. 
 
 -15 
 
 — 46.6 
 
 + 42 
 
 — 7.8 " 
 
 — 6.6 
 
 The results for Z>, Table III., show that with two exceptions 
 (one half and four minutes) the difference due to the filling has 
 
45» 
 
 MABEL LORBNA NELSON. 
 
 a negative sign, where in Table I. it was positive, indicating 
 that in general the filled time seemed shorter than the empty. 
 
 Table IV. 
 Subject R. E-E. 
 
 Interval. 
 
 Av. Estimate. 
 
 •ai 
 
 M.V.95 
 
 Median. 
 
 Tif 
 
 VL.V.i 
 
 yi min. 
 
 28.2 sees. 
 
 — 6 
 
 27.7 
 
 23.5 sees. 
 
 — 21.6 
 
 29-3 
 
 I " 
 
 I min. 10.8 " 
 
 + 18 
 
 23-4 
 
 I min. " 
 
 
 
 24.1 
 
 2 " 
 
 I " 33-2 " 
 
 — 25-5 
 
 243 
 
 I " 28 
 
 — 26.6 
 
 245 
 
 4 " 
 
 2 " 20.5 " 
 
 -41.5 
 
 25 
 
 2 " 14 " 
 
 — 44-1 
 
 ib.5 
 
 6 " 
 
 3 " 41-4 " 
 
 -38.5 
 
 19.2 
 
 3 " 56 " 
 
 — 34-4 
 
 I6.7 
 
 lO " 
 
 6 " 32.9 " 
 
 — 34-5 
 
 25-7 
 
 5 " 54-5 " 
 
 — 40.9 
 
 23.1 
 
 F-E. 
 
 Yz min. 
 
 
 31.4 sees. 
 
 + 4.6 
 
 30.3 
 
 
 37 sees. 
 
 + 23.3 
 
 22.7 
 
 I " 
 
 I mm. 
 
 4-7 " 
 
 + 7.8 
 
 7.4 
 
 I mm. 
 
 2 •' 
 
 + 1.6 
 
 6.9 
 
 2 " 
 
 2 " 
 
 19.4 " 
 
 + 16. 1 
 
 29.2 
 
 2 " 
 
 20 " 
 
 + 1.6 
 
 21.8 
 
 4 " 
 
 2 " 
 
 57.6 ". 
 
 — 26 
 
 28.2 
 
 2 " 
 
 34 " 
 
 -30.5 
 
 29-3 
 
 6 " 
 
 5 " 
 
 52 
 
 — 3-3 
 
 11.6 
 
 6 " 
 
 I " 
 
 + 
 
 10.7 
 
 10 " 
 
 6 " 
 
 15-4 " 
 
 — 34-1 
 
 19.4 
 
 5 " 
 
 49 " 
 
 — 41.8 
 
 19-3 
 
 Difference due to Filling. 
 
 Median. 
 
 + 44.9 per cent. 
 
 + 1.6 
 + 28.2 
 + 13-5 
 4-34-4 
 - -9 
 
 Subject R, in Table IV., shows a positive difference, with 
 the exception of the interval of one minute, where the median 
 and average give conflicting results, and of the interval of ten 
 minutes, where there is practically no effect. 
 
 We have in the tables four sets of figures that represent the 
 effect of the filling on the estimates of D and of R. These 
 figures are based on the average and the median of each of the 
 two groups of experiments. I think we may safely infer that 
 when the average and the median for any given interval of the 
 same group have opposite signs, there is no clear effect due to 
 the filling. The common result for these four modes of com- 
 parison would then be that the effect of the filling was to make 
 the time seem shorter to D during the intervals of one, two, six 
 and ten minutes. The two groups give conflicting results for 
 the intervals of one half and four minutes, so that the position 
 
VISUAL ESTIMATE OF TIME. 
 
 453 
 
 of the filling — whether it came in the first or second of the in- 
 tervals — was the more important factor. All four modes of 
 comparison agree that to R the filled time seemed longer dur- 
 ing all intervals except one half and one minute. In these two 
 intervals the position of the filling is again the chief factor. In 
 the case of the third subject, 6", we have but one group of ex- 
 periments. Here the filled time seemed longer at one minute 
 but shorter at two, six and ten minutes. At one half and four 
 minutes there seems to be no clear effect due to the filling. 
 
 It is evident from these results that the filling does not affect 
 all three subjects alike. In general, the filled time seemed 
 shorter than the empty to D and S^ but longer to 7?, though 
 there are exceptions in all three cases. 
 
 Table V. 
 Subject 5. E-E. 
 
 Interval. 
 
 Av. Estimate. 
 
 ■Di 
 
 M.V.S« 
 
 Median. 
 
 DS< 
 
 M.V.5( 
 
 yi min. 
 
 43.6 sees. 
 
 + 43-6 
 
 20.4 
 
 40.5 sees. 
 
 + 35 
 
 25.4 
 
 I " 
 
 I min. 6 " 
 
 + 10 
 
 15-7 
 
 I min. 2 " 
 
 + 3-3 
 
 27.7 
 
 2 " 
 
 2 " 26.4 " 
 
 + 22 
 
 27.7 
 
 2 " 47 " 
 
 + 39-1 
 
 21.9 
 
 4 " 
 
 3 " 39-9 " 
 
 - 8.3 
 
 17.2 
 
 3 " 47 
 
 — 5-4 
 
 16. 1 
 
 6 " 
 
 5 " 48.5 " 
 
 — 3-1 
 
 26.6 
 
 6 " 2 " 
 
 + 3.3 
 
 24.8 
 
 lO " 
 
 10 " 10.6 " 
 
 + 1-7 15-4 1 
 
 II " 5 
 
 + 10.8 
 
 5.9 
 
 F-E. 
 
 Vz 
 
 I 
 
 2 
 
 4 
 
 6 
 
 10 
 
 I min. 
 I " 
 
 3 " 
 
 4 " 
 
 44.2 sees. 
 
 + 47.3 
 
 21.3 
 
 40.9 " 
 
 + 68.1 
 
 15-3 
 
 56 " 
 
 — 3-3 
 
 15.8 
 
 50.4 " 
 
 — 4 
 
 15-4 
 
 42.2 " 
 
 — 18.8 
 
 10.8 
 
 59-1 " 
 
 — 10. 1 
 
 311 
 
 I min. 
 I " 
 
 3 " 
 
 4 " 
 9 " 
 
 39 
 
 44 
 
 55 
 
 33-5 
 
 22 
 
 3-5 
 
 ecs. 
 
 + 30 
 + 76.6 
 
 — 4.1 
 
 
 — 11.2 
 
 
 — 27.2 
 
 - 9-4 
 
 21.5 
 16 
 
 15.9 
 15 
 
 9-4 
 II. 2 
 
 Difference due to Filling. 
 
 
 Average. 
 
 Median. 
 
 yi min. 
 
 + 3.7 per eent. 
 
 — 5 
 
 per 
 
 eent. 
 
 I " 
 
 + 58.1 
 
 + 73-3 
 
 
 
 2 " 
 
 — 25.3 
 
 — 43-2 
 
 
 
 4 '• 
 
 + 4.3 " 
 
 - 5.8 
 
 
 
 6 " 
 
 — 15.7 
 
 — 30.5 
 
 
 
 10 " 
 
 — 11.8 
 
 — 20.2 
 
 
 
 The estimates of empty times as compared with empty times, 
 of the three subjects, as shown in Tables III., IV. and V., are 
 in all respects comparable. If we consider only those intervals 
 
454 MABEL LOR EN A NELSON. 
 
 where the average and the median are of the same sign, as de- 
 cisive, we have for D no apparent error at one half or one 
 minute, a positive error at two minutes, a negative error at four 
 and six minutes, and no error at ten minutes. 
 
 The results do not show a constant negative error, such as 
 was found by Michael Ejner for intervals of one half, one, two, 
 three and four minutes marked off by sound. I found in taking 
 the estimates that when a short interval followed a longer one it 
 was in general lengthened. This fact may in part account for 
 the overestimation of the shorter intervals. 
 
 When we compare the estimates of empty times of D and 
 R with those of the first group. Tables I. and II., we find that 
 D has lengthened his estimates in this second group (compare 
 Tables I. and II.). This change was not, I think, due to prac- 
 tice so much as to the increased strain of attention demanded 
 by the lack of knowledge of the probable length of the stand- 
 ard. R has decreased the estimate of one half minute, and, in 
 general, made the estimates of Table IV. smaller than those of 
 Table II. 
 
 For all intervals longer than one or two minutes my subjects 
 expressed a dissatisfaction with their estimates and felt that they 
 made little, if any, difference between the longer intervals — all 
 times seeming very long and very much alike. R^ at times, 
 could not consciously note any difference between standards of 
 two and six minutes, or between those of four and ten minutes, 
 even when they followed each other in close succession, though 
 her results show a constant and decided difference. D had 
 a better idea ; for, when asked how long he thought an inter- 
 val had been, his verbal answer more nearly approximated the 
 duration he had just marked off as ' equal ' in the experiment. 
 S entered the experiments with a general knowledge of the 
 lengths of time that were to be used as standards, though igno- 
 rant during the experiments as to what particular one was being 
 given him — but beyond two minutes could not with any constancy 
 identify them and tell whether the standards had been four, six 
 or ten minutes. 
 
 During the longer periods it was impossible to keep the 
 attention so closely fixed as during the intervals of one half and 
 
VISUAL ESTIMATE OF TIME. 455 
 
 one, or at most two minutes. It is at about this point that the 
 change of sign occurs in the estimates. The general feeling 
 of weariness seemed to be the chief criterion in the longer in- 
 tervals. 
 
 The difference due to the filling was, I think, merely a dif- 
 ference in the direction of attention, the monotonous regularity 
 of the lights being, in general, a means of holding the attention 
 and preventing the mind from wandering. From this point of 
 view the filled time was psychologically the more empty or 
 barren of the two — the time being filled with monotonous sensa- 
 tions of light, but empty of vivid or interesting trains of thought. 
 In looking back over it, then, there would be fewer changes in 
 consciousness to remember, and hence the time would seem 
 shorter. This would be in keeping with the fact that the in- 
 creased mental activity produced by certain narcotic drugs 
 makes time seem long ; the person, on recovery, remembering 
 the vast number of his experiences, overestimates the time. 
 
 What is the result of these experiments as compared with 
 Dr. Meumann's, and with the space illusions of sight and touch? 
 "We find that in sight a space is overestimated when it is filled ; 
 an interrupted line will seem longer than a continuous one, a 
 line divided into more than two parts longer than an undivided 
 one of the same length. In touch, while an interrupted line 
 of lo mm. is underestimated, yet a longer one, lo cm., will be 
 overestimated when it is interrupted.* Whether the effect of 
 the filling in these time intervals corresponds to that in the 
 space illusions would depend on which of the two times we con- 
 sider to be the filled ; for, in these long intervals the sensations 
 of light have but an indirect influence, and are not the only fill- 
 ing, nor the chief factor in the appreciation of time. Taking 
 it, however, as ordinarily understood, we do not find here a 
 constant negative error such as Dr. Meumann found in his long- 
 est times, although to two of the subjects, D and S, the filled 
 time in general seemed shorter. 
 
 The results of the third subject, 7?, are more in accord with 
 the space illusion of sight, and of touch when the standard is 
 one of lo cm. — the filling making the stretch seem longer. 
 
 ^ See the accompanying paper by Miss Robertson, already referred to. 
 
456 
 
 MABEL LOR EN A NELSON. 
 
 To test the question as to the effect of single and multiple 
 divisions of time, and to determine whether in the temporal esti- 
 mate there was anything like the space error in vision, where 
 halving produces a negative error and more divisions a positive 
 one, visual intervals of 3, 6, 12, 18, 30 and 60 seconds were, by 
 the same method as that described above, divided into halves, 
 thirds and fourths. 
 
 Under each interval ten estimates were taken for an empty 
 time, and ten for each character of filling, on each of two sub- 
 jects. A pause of two seconds was made between the standard 
 and the compared time, the compared time being here always 
 empty. In order that the subjects might know when the end 
 of the standard had arrived, the word 'now' was spoken im- 
 mediately after the last flash of the standard. A stop-watch 
 measuring two tenth seconds was used by the experimenter to 
 mark off the estimate. Although there was a reaction error 
 here, yet it was common to both sets of experiments alike, and 
 •so might be neglected in comparing them. 
 
 Table VI. 
 Subject R. 
 
 Interval. 
 
 No. of Lights. 
 
 Average. 
 
 M. V.i 
 
 Median. 
 
 M. v. i 
 
 3 sees. 
 
 2 
 
 3-94 
 
 10 
 
 4 
 
 9 
 
 
 3 
 
 4.24 
 
 24 
 
 4 
 
 25 
 
 
 4 
 
 4.71 
 
 15 
 
 4.7 
 
 14 
 
 6 " 
 
 2 
 
 6.28 
 
 16 
 
 6 
 
 16 
 
 
 3 
 
 6.88 
 
 20 
 
 6.5 
 
 20 
 
 
 4 
 
 8.82 
 
 16 
 
 8.4 
 
 16 
 
 
 5 
 
 8.80 
 
 15 
 
 9.2 
 
 14 
 
 12 " 
 
 2 
 
 10.62 
 
 17 
 
 9.8 
 
 17 
 
 
 3 
 
 10.96 
 
 13 
 
 10.4 
 
 10 
 
 
 4 
 
 12.88 
 
 9 
 
 12.2 
 
 9 
 
 
 5 
 
 13.38 
 
 8 
 
 13-8 
 
 7 
 
 18 " 
 
 2 
 
 13-24 
 
 16 
 
 13 
 
 15 
 
 
 3 
 
 13.46 
 
 22 
 
 13.3 
 
 21 
 
 
 4 
 
 16.44 
 
 13 
 
 17-3 
 
 12 
 
 
 5 
 
 14.10 
 
 9 
 
 13-6 
 
 8 
 
 30 " 
 
 2 
 
 20.04 
 
 16 
 
 19. 1 
 
 17 
 
 
 3 
 
 20.22 
 
 23 
 
 19 
 
 20 
 
 
 4 
 
 19.66 
 
 20 
 
 16.6 
 
 29 
 
 
 5 
 
 24.58 
 
 26 
 
 23.9 
 
 22 
 
 60 " 
 
 2 
 
 32.84 
 
 26 
 
 28.7 
 
 26 
 
 
 3 
 
 35.90 
 
 35 
 
 30.9 
 
 37 
 
 
 4 
 
 39-76 
 
 19 
 
 40.1 
 
 19 
 
 
 5 
 
 35-56 
 
 19 
 
 32.7 
 
 16 
 
VISUAL ESTIMATE OF TIME. 
 
 Table VII. 
 Subject Rd. 
 
 457 
 
 Interval. 
 
 No. of Lights. 
 
 Average. 
 
 M. V. 5f 
 
 Median. 
 
 M. V.f, 
 
 3 sees. 
 
 2 
 
 3-74 
 
 19 
 
 3-8 
 
 18 
 
 
 3 
 
 4-56 
 
 13 
 
 4.5 
 
 13 
 
 
 4 
 
 4.28 
 
 10 
 
 4.4 
 
 10 
 
 6 " 
 
 2 
 
 4.80 
 
 8 
 
 4.8 
 
 6 
 
 
 3 
 
 6.68 
 
 17 
 
 6.9 
 
 16 
 
 
 4 
 
 7-44 
 
 16 
 
 7-1 
 
 15 
 
 
 5 
 
 8.36 
 
 12 
 
 8.7 
 
 12 
 
 12 " 
 
 2 
 
 10.07 
 
 14 
 
 10 
 
 14 
 
 
 3 
 
 10.34 
 
 19 
 
 9-3 
 
 20 
 
 
 4 
 
 II. II 
 
 22 
 
 9-9 
 
 22 
 
 
 5 
 
 11.48 
 
 16 
 
 11.6 
 
 16 
 
 i8 " 
 
 2 
 
 11.05 
 
 12 
 
 10.3 
 
 14 
 
 
 3 
 
 13-83 
 
 II 
 
 14-35 
 
 9 
 
 
 4 
 
 12.76 
 
 14 
 
 13-8 
 
 II 
 
 
 5 
 
 15-35 
 
 12 
 
 15-3 
 
 10 
 
 30 '« 
 
 2 
 
 17.41 
 
 14 
 
 16.3 
 
 14 
 
 
 3 
 
 18.17 
 
 13 
 
 17-75 
 
 13 
 
 
 4 
 
 17.99 
 
 18 
 
 16.35 
 
 16 
 
 
 5 
 
 18.63 
 
 II 
 
 19.4 
 
 16 
 
 60 " 
 
 2 
 
 30.64 
 
 12 
 
 30.4 
 
 II 
 
 
 3 
 
 34-56 
 
 16 
 
 34.3 
 
 17 
 
 
 4 
 
 30.71 
 
 II 
 
 29.9 
 
 II 
 
 
 5 
 
 33-54 
 
 17 
 
 34.2 
 
 16 
 
 The result we find (see Tables VI. and VII.) is that whether 
 the average or the median be taken as the basis for comparison, 
 the empty time seemed shorter than the filled, and, in general, 
 the time seemed longer as the number of impressions was in- 
 creased. For the three longer periods — eighteen, thirty and 
 sixty seconds — the standard when divided into halves seemed 
 longer than when divided into thirds to Rd ; while to R the 
 standard when divided into thirds seemed longer than when 
 divided into fourths, during the intervals of eighteen and sixty 
 seconds. 
 
 It is probable that in these longer periods the attention is not 
 held closely to the sensations of light, so that other factors play 
 a greater part in determining the estimate. In the shorter in- 
 tervals, however, the mind can be kept relatively empty, so 
 that the sensuous filling is the chief measure of duration. As 
 long as the attention could be concentrated on the sensations, 
 the number of lights would, I think, affect the estimate. Cases 
 where in the present experiments the standard was subdivided 
 
45^ MABEL LORENA NELSON. 
 
 into thirds could always be consciously distinguished from those 
 divided into halves, but many times where the standard was 
 divided into fourths it could not be distinguished from thirds ; 
 more than fourths, I feel sure, could not have been appre- 
 hended without counting. 
 
 From these results we would say that in relatively short 
 times as well as in spaces, the estimate is influenced by the 
 number of impressions that fall within the stretch. There is no 
 evidence whatever of a shortening up of the estimate due to the 
 division of the standard into halves, such as is found in vision. 
 
 With Rd the division of the standard into fourths always 
 gives a greater estimate than the division into thirds, but the 
 estimate of thirds is often less than that of halves. 7?, with 
 but three exceptions, increases the estimate as the number of 
 divisions increases. 
 
 We find a great similarity in the absolute durations given in 
 the estimate of the two subjects. Practice on longer intervals 
 does not enable R to judge these shorter intervals any more 
 accurately than Rd^ who had no former practice, nor does it 
 tend to reduce the variation ; this being as large as in the 
 former experiments and somewhat larger than that of Rd. 
 
 The position of the indifference point — where there is no 
 absolute over- or underestimation — lies with both R and Rd 
 between six and twelve seconds. The overestimation of three 
 and six seconds may be due to assimilation with longer inter- 
 vals. This would correspond with the results of Estel,^ who 
 found that an interval of three seconds, when it followed one of 
 two seconds, seemed shorter than when it followed one of four 
 seconds. This would also explain the shortening up of the esti- 
 mates of empty intervals of thirty and sixty seconds in the case 
 of subject R as compared with her former estimates given in 
 Tables II. and IV. 
 
 As a final result of these experiments we find, in intervals 
 of time ranging from three to sixty seconds, evidence of a tem- 
 poral illusion very similar to the space illusion of sight. Both 
 in time and in visual space, when there is more than a single 
 division, the filled stretch is overestimated. We do not find, 
 
 ^ Philosophische Studien, II., p. 55. 
 
VISUAL ESTIMATE OF TIME. 459 
 
 however, that a single division shortens up the temporal estimate. 
 This is in keeping with the space illusion of touch when the 
 standard is lo cm., but opposed to Dr. Meumann's results, as 
 he finds intervals from four to nine seconds are underestimated 
 when a single division is used. 
 
 As we increase the length of the standard interval to min- 
 utes, we do not get a direct reversal of the effect of the filling 
 such as is found in touch ; but we find the illusion either de- 
 creases or is entirely lost. 
 
 linWtj of California 
 
 i^liolaglcal Laboratoiy. 
 
4 
 
REPRINTED FROM 
 
 VOL IX. No. 6. November, 1902. 
 
 THE 
 
 Psychological Review 
 
 EDITED BY 
 J. McKEEN CATTELL J. MARK BALDWIN 
 
 Columbia University Princeton University 
 
 WITH THE CO-OPERATION OF 
 ALFRED BINET, Ecole des Hautes-Studes, Paris; JOHN DEWEY, H. H. DONALD- 
 SON, University of Chicago ; G. S. FULLERTON, University of Pennsylvania ; 
 G. H. HOWISON, University of California; JOSEPH JASTROW, Uni- 
 versity OF Wisconsin; G. T. LADD, Yale University; HUGO 
 MONSTERBERG, Harvard University; M. ALLEN STARR, 
 College of Physicians and Surgeons, New York ; CARL 
 STUMPF, University, Berlin ; JAMES SULLY, 
 University College, London. 
 
 H. C. WARREN, Princeton University, Associate Editor and Business Manager. 
 
 STUDIES FROM THE PSYCHOLOGICAL LABORATORY 
 OF THE UNIVERSITY OF CALIFORNIA. 
 
 COMMUNICATED! BY PROFESSOR GEORGE M. STRATTON. 
 
 VI. ' Geometric-Optical' Illlusions in Touch. 
 
 BY DR. ALICE ROBERTSON. 
 
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[Reprinted from The Psychological Review, Vol. IX., No. 6, Nov., 1902.] 
 
 STUDIES FROM THE PSYCHOLOGICAL LABORA- 
 TORY OF THE UNIVERSITY OF CALIFORNIA. 
 
 COMMUNICATED BY PROFESSOR GEORGE M. STRATTON. 
 
 VI. 'Geometric-Optical' Illusions in Touch. 
 
 BY DR. ALICE ROBERTSON. 
 
 The interest which attaches to experiments upon the so- 
 called 'geometric-optical' illusions, viz., the investigation of 
 our perception of space, is not lessened when the investigation 
 is carried into the tactual field. The experiments recorded in 
 the following pages constitute an attempt to investigate, by 
 touch alone, certain geometrical figures which present well- 
 known optical illusions. Since sight and touch are so closely 
 related, and since our theories of space perception are based in 
 the main upon optical phenomena, the following observations 
 may serve to test some of these theories. For example, from his 
 study of reversible perspective, Thiery^ arrives at the conclu- 
 sion that all optical illusion is due to the perspective in any 
 given figure, whether consciously or unconsciously perceived. 
 According to this observer, the convergence or divergence of 
 lines produces in us an effect of depth, or of foreshortening, so 
 that small angles are only larger ones interpreted perspectively, 
 and an object seen near the apex of an angle seems larger than 
 one at its opening, because it appears to be further away, and 
 we connect distance with larger size. It is obvious that the 
 tactual perception of plane figures, the mere contact of the fin- 
 gers or of the hand upon any part of a flat surface, can produce 
 no effect of perspective. When, however, it is found that illu- 
 sion remains, serious doubt is cast upon the importance of per- 
 spective, even in the sight illusion. 
 
 In considering what figures are suitable for experimentation 
 in the tactual field, it is clear that not all figures which pro- 
 
 ^ Phil. Stud., XI., pp. 307 and 603, XIL, p. 67. 
 
 549 
 
 Mmii] of U\\m 
 
 Psyfiiioiogical Laboratoni. 
 
55° ALICE ROBERTSON. 
 
 duce an effect upon sight can be used. Simple figures, those 
 containing but few lines, are best adapted to this purpose. If 
 the figure is composed of many lines, a blur of sensations is 
 received, and, as would be said in microscopy, it is difficult to 
 get a sharp definition. The apparatus which was used in the 
 following experiments consisted of black cardboard in which 
 the figures were pricked with a fine cambric needle, the 
 prickings being placed so close together that they could not 
 tactually be distinguished as separate points. Or, in a few 
 cases, the shape of the figure to be experimented with was made 
 by pasting narrow strips upon a larger piece of cardboard, and 
 this outline was either explored by the tips of the fingers, or the 
 hand as a whole was passed over the figure. 
 
 Throughout these experiments, active touch has been em- 
 ployed. The rapidity of movement, the amount of pressure ex- 
 erted, and the portion of the hand which received the sensation, 
 make marked differences in some cases in the amount of illu- 
 sion. Sometimes an illusion which existed in a very marked 
 degree when the hand as a whole was passed over the figure, 
 became almost inappreciable if the finger-tips were freely used 
 to explore the contour. In other cases the illusion remained 
 whichever method was adopted. As a rule, the hand has been 
 passed rather lightly and somewhat rapidly over the figure, and 
 the judgment has been recorded either in words or in a drawing 
 of the object as it was perceived by the tactual sense. 
 
 The agreement or divergence between the illusions of touch 
 and of sight afford a wide basis of classification for the experi- 
 ments here described. In very few cases only can the tactual 
 illusion be said to be merely in the same, or in a reverse direc- 
 tion from that which is found in sight. Other phenomena of 
 illusion also appear, e. g.^ illusions of curvature where lines are 
 straight, or illusions of greater length or height where no dif- 
 ference exists in reality. Generally speaking, however, the 
 whole set of experiments is divisible into two classes. The 
 first includes those figures in which the illusion follows the 
 same direction as that of sight. The second includes those fig- 
 ures which afford an illusion in the opposite direction. Other 
 phenomena connected with these figures will be noticed in the 
 description. 
 
GEOMETRIC-OPTICAL ILLUSIONS IN TOUCH. 55 1 
 
 Class I. 
 
 The experiments which fall under the first class consist of a 
 miscellaneous group of minor illusions which are common and 
 well known in the field of sight. The purpose has not been to 
 make a complete investigation of the phenomena revealed here, 
 but merely to find out whether illusion exists, and, if so, to what 
 extent it resembles the visual phenomena. These figures were 
 presented from time to time to several subjects, no attempt being 
 made, except in one or two cases, to vary the conditions. 
 
 I. Milller-Lyer Illusion. — In this well-known figure a 
 marked tactual illusion exists. For purposes of experiment the 
 oblique lines at the extremities of the horizontals were not joined 
 close to the latter. Space enough was left so that the ends of 
 the horizontals could be distinctly felt. In every case illusion 
 
 / 
 
 
 / 
 
 A 
 
 \ 
 
 X 
 
 \ 
 
 B 
 
 Fig. I. Fig. 2. Fig. 3. 
 
 in regard to the length of the line was very apparent. It was in 
 the same direction as that found in sight, but greatly intensified. 
 That is, when compared by the sense of touch alone, A (Fig. 
 i) seemed not only longer than B, but the difference in length 
 between them seemed much greater than appears to sight. 
 
 2. Illusion of Convergent Lines. — Experimentation upon a 
 suitable figure of the pattern represented in the drawing gave 
 perfectly definite and unvarying results. When the hand is 
 passed over the figure and the sizes of the two circles are com- 
 pared, that one {A) which is in the apex of the angle seems the 
 larger — a result similar to that which is found in sight. 
 The result in question seems to be due to a blending, to a cer- 
 tain degree, of the sides of the angle with the periphery of the 
 circle and an interpretation of this as meaning that the circle A 
 is larger than B^ B being relatively uninfluenced by the lines 
 
552 ALICE ROBERTSON. 
 
 near it. If this be true, then the apparent size of A relative 
 to B should change with a change in its position relative to the 
 apex of the angle. This supposition seems to be confirmed by 
 a few experiments conducted for the purpose of testing it. 
 
 3. Perception of Angles. — In the optical illusion presented 
 by Fig. 3, the circle seems to be flattened somewhat where it 
 touches the corners of the square, while the sides of the latter 
 are very slightly bent inward. The same phenomena greatly 
 accentuated appear also in the tactual illusion. In experiment- 
 ing with this figure, subjects were requested not to explore the 
 contour with the figure-tips. A record of the impression received 
 by passing the hand back and forth over the figure as a whole, 
 was made in drawing by each subject, and samples of the data 
 obtained from two subjects, S and TV", are given below (Figs. 
 4 ''ind 5). 
 
 Fig. 4 represents the impression which subject S received 
 
 Fig. 4. Fig. 5. Fig. 6. 
 
 when the hand was passed over the figures as a whole in any 
 direction. The sides of the square curved inward, and the 
 periphery of the circle seemed to be divided into distinct seg- 
 ments, which flattened very much as their extremities ap- 
 proached the corners of the square. 
 
 Fig. 5 represents the impression received by subject iV^ of 
 the same figure. In this case the hand was passed from right 
 to left or vice vcisa across the figure as a whole, at which time 
 the square lengthened horizontally, the shorter sides only seem- 
 ing to curve slightly inward. The circle seemed to be an 
 ellipse somewhat flattened at the corners of the inner rectangle. 
 When the figure was turned through 45°, and the hand was 
 moved as before from right to left and back again, then the 
 square became a flattened diamond shape, and the circle an 
 ellipse somewhat flattened at the corners of the inclosed figure 
 
GEOMETRIC-OPTICAL ILLUSIONS IN TOUCH. 
 
 553 
 
 (Fig. 6.) To this subject, ' horizontal ' distances, that is, dis- 
 tances right and left, seem distinctly longer than equal vertical 
 ones. Also, the upper part of a figure which is felt by the hand 
 as a whole, usually seems higher and more distinct than the 
 lower part of a symmetrical figure. Thus, in the two positions 
 recorded above (Figs. 5 and 6) the curve of the ellipse is higher 
 above than below, as is also the point of the diamond in Fig. 6. 
 4. Illusions of Contour. — A tactual illusion similar to that 
 
 Fig. 7. 
 
 Fig. 8. 
 
 which is found in sight appears also when the hand is passed 
 over two semicircles, the one closed and the other open, as 
 represented in the drawing (Fig. 7). In this case the arc of 
 the open semicircle seems to flatten out and to become the arc 
 of a larger circle. Besides this illusion in contour another one 
 appears in A which is not observed in sight. When the con- 
 tour of A is perceived by the hand as a whole, the first impres- 
 sion is that of a figure composed of two curves, one of which is 
 flatter than the other (Fig. 8). The curve of the arc of the 
 circle seems to impress itself upon the chord and it appears to 
 bulge slightly. 
 
 Similarly, if the two squares A and B (Fig. 9) are compared 
 in the manner above described for the semicircles, the open 
 figure B will seem the larger. In some cases A is felt as a 
 square, ^ as a rectangle whose longer sides are horizontal. 
 In other cases both A and B seem to be lengthened rectangles, 
 B seeming the longer of the two. In the comparison of the 
 semicircles and of the squares, the illusion in each case corre- 
 sponds to what we find in sight, and probably for a similar rea- 
 son, viz., the inclusion within the figure of some of the outside 
 free space. 
 
554 
 
 ALICE ROBERTSON. 
 
 5. Ring Segments. — When the two segments (Fig. 10), 
 which are objectively equal, are compared by touch, an illusion 
 similar in direction to that of sight is very evident. Not only is 
 a tactual illusion apparent when the segments are objectively 
 equal, but also when the upper segment is actually larger than 
 the lower, and when to sight no illusion whatever exists. That 
 is, it is found by experimentation that, if two segments are com- 
 pared in which the inner curve of the upper segment is equal to 
 the upper curve of the lower (Fig. 11), a tactual illusion is 
 apparent in a larger number of cases. In Fig. 10, 80^ of the 
 judgments obtained from five persons were in accord with the 
 ordinary visual illusion, that is, A seemed smaller than B. At 
 the same time, in the other 20^ of the judgments, A was con- 
 
 A 
 
 B 
 
 Fig. 9. 
 
 sidered either larger or equal to B, or the subject was in doubt. 
 The evidence for illusion in this figure is by no means so conclu- 
 sive, so unvarying in its effect on the tactual sense, as it is in 
 vision. On the other hand, it is remarkable that in the unequal 
 segments represented in Fig. 11, so large a percentage of judg- 
 ments should give evidence of a tactual illusion. The larger 
 size of A in Fig. 11 is very evident to the eye, yet when the 
 comparison is made by touch, in 42^ of the judgments A is 
 considered smaller or equal in size to B. If the cards are 
 turned at right angles, and the segments are compared in this 
 position, the errors in judgment are increased. In the case of 
 Fig. 10, the increase is not large, 81^ of the judgments are in 
 favor of the smaller size of A, while for Fig. 11, 56^ of the 
 judgments are that A is either smaller than B or equal to it. 
 The error in these figures seems to indicate that the tactual 
 comparison of the two segments becomes a comparison of the 
 lengths of the two more closely approximated curves, rather 
 
GEOMETRIC-OPTICAL ILLUSIONS IN TOUCH. 
 
 555 
 
 than a comparison of the size of the segments as a whole. 
 This is thought to be the reason why an increase of errors 
 occurs when the cards, and consequently the segments, are 
 turned at right angles to the positions represented in Figs. lO 
 and II. In this position the oblique sides of the segments are 
 brought directly under the fingers, and hence come into more 
 prominent notice. The tips of the fingers naturally follow the 
 slanted edge of the upper or right-hand segment, and thus they 
 are brought some distance within the slanted edge of the lower, 
 or left-hand segment, and the former is considered the smaller. 
 
 A 
 
 In each of the preceding figures certain tactual illusions oc- 
 cur which are in the same direction as those which appear to 
 the eye and which seem analogous to the optical illusions. As 
 has been said, these optical phenomena have been ascribed to 
 perspective as the primary cause ; but in the experiments here 
 presented perspective cannot enter, and yet the results are the 
 same. While it does not necessarily follow that the phenomena 
 of sight and touch should be referred to the same cause, yet the 
 results here obtained are thought to diminish the force of per- 
 spective as a fundamental cause of illusion even in sight. 
 
556 ALICE ROBERTSON. 
 
 Class II. 
 
 I. A ^lantitative Comfai-ison of Lines of a Varying Num- 
 ber of Interruptions with an Uninterrupted Line of Standard 
 Length. — The experiment here described is intended to investi- 
 gate the phenomena which appear when lines variously inter- 
 rupted are compared, by the sense of touch alone, with an unin- 
 terrupted line. The results show a reversal of the illusion which 
 appears in the visual field, and instead of an overestimation of 
 the interrupted extents such as takes place in vision, there is 
 underestimation, i. e., the interrupted lines seem shorter than 
 they actually are. 
 
 The apparatus which was used consisted of a number of 
 cards, made of black cardboard, 27 cm. long by 13 cm. wide, 
 in the center of which the lines were pricked. Four kinds of 
 lines were used. First, a plain, uninterrupted, smoothly pricked 
 
 line ( ). Secondly, a line similar to the preceding 
 
 but having its extremities defined by a short line at right angles 
 
 ( I I ). Thirdly, a line defined at each extremity by 
 
 cross lines and also divided in the middle ( | 1 1 ) ; 
 
 and fourthly, a line divided in a similar manner into sixths 
 ( I— I— i— I— I— I— I )• The cards thus fall into four groups, each 
 group consisting of a series of lines varying in length from 7 
 cm. to 15 cm. The lines varied by steps of 5 mm. throughout 
 that portion of the series where the difference was actually 
 found to be difficult to perceive. The lengths of the lines com- 
 posing a series, then, were as follows: 7, 8, 9, 9.5, 10, 10.5, 
 II, II. 5, 12, 12.5, 13, 14, 15 centimeters. The standard line 
 with which all comparisons were made, was a plain unbroken 
 line ( ) ten centimeters in length. 
 
 In conducting the experiment the subject was seated with 
 closed eyes before a table of convenient height, upon which his 
 whole arm rested comfortably. The standard card was first 
 presented to him, and then the other cards of any particular set, 
 one after the other, were laid below it for his comparison. He 
 was permitted to pass the hand back and forth from the card to 
 be compared to the standard, and vice versa, as often as he 
 pleased before he gave his judgment. The right hand was 
 always used, and no restrictions were placed upon him as to 
 
GEOMETRIC-OPTICAL ILLUSIONS IN TOUCH. 
 
 557 
 
 what part of the hand should receive the 
 stimulation. Sometimes the tips of the 
 fingers alone were used, again the por- 
 tion of the hand just below the finger- 
 tips. In giving a judgment the subject 
 was asked to state whether the line 
 seemed longer or shorter than the stand" 
 ard or equal to it. A series consisted of 
 an ascending and descending portion, 
 and an equal number of each began 
 with the shortest line and proceeded 
 gradually to the longest, and vice versa. 
 
 Ten such double series were obtained 
 from each of three subjects, B^ S and 
 JY, the results of which are shown in 
 Table I. As a matter of fact, series 
 were obtained from many more persons* 
 and the results in many cases were much 
 more striking than those which are here 
 presented. The experiments here re- 
 corded are, however, in every way the 
 most systematic and trustworthy. In 
 the table each value for the upper (U. T.) 
 and lower (L. T.) threshold is an aver- 
 age of twenty single determinations, and 
 the equality point (E. P.) and mean vari- 
 ation (M. V.) are an average of forty de- 
 terminations. 
 
 Examination of the table of thres- 
 holds shows much individual variation 
 in the ability to estimate the differences 
 between the various lines. All show un- 
 derestimation, that is, the line which is 
 compared, when really equal to a stand- 
 ard, seems shorter than the standard, 
 even in Group I. There seems to be 
 much difficulty for all subjects to discrim- 
 inate in the case of this group. In the 
 
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55 S ALICE ROBERTSON. 
 
 cases here reported one subject, S, shows an underestima- 
 tion amounting to i cm., the other two subjects each aver- 
 age about one half a centimeter of error. The amount of 
 error in the case of subject S is always large, but increases 
 at an even rate with the number of interruptions, so that the 
 line with the greatest number of interruptions seems in his 
 case to be the shortest. For subject B the amount of un- 
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 the same even pace, and a line much divided seems shorter 
 than one objectively equal but undivided. The case is some- 
 what different for N. For this subject the effect of the limit- 
 ing lines at the extremities in Group II. is marked by a sudden 
 increase in the amount of underestimation. The compared line 
 in Group II. seems to be shortest of all, while the compared 
 lines in Groups III. and IV. relatively lengthen. But even 
 with this subject the line containing the greater number of in- 
 terruptions is equal to the uninterrupted line and not longer, as 
 is the case in sight. 
 
 From the data furnished by these experiments, we may con- 
 clude that when a line ten centimeters in length, definitely 
 marked at its extremities, and with or without interruptions in 
 its length, is compared with a plain unbroken line objectively 
 equal to it, it appears shorter to the tactual sense, or is un- 
 derestimated. In general, this result agrees with the conclu- 
 sion at which Professor Parrish ^ arrived in his investigation of 
 similar phenomena with passive touch. He used lines 64 mm. 
 long, all being marked at their extremities and variously inter- 
 rupted in their extents. He considers that the results which he 
 obtained clearly point to a reversal of the optical phenomena. 
 Dr. Dresslar,^ on the other hand, concludes from experiments 
 which he conducted with both active and passive touch, that the 
 tactual illusion follows the same direction as the illusion of 
 sight. A study of the data of the latter's experiments, how- 
 ever, given in Tables I. and II., pp. 334, 335, of his article, 
 suggests that perhaps a transition-point from under- to overesti- 
 mation may be found in them, between the long and the short 
 
 ^ Amer. Jotir. of Psy., VI., p. 514. 
 ^ Amer. Jour, of Psy., VI., p. 314. 
 
GEOMETRIC-OPTICAL ILLUSIONS IN TOUCH. 559 
 
 interrupted intervals. Certainly in Table II., in which the judg- 
 ments are given upon longer lines (5 to 16 cm.), there is a de- 
 cided falling off of the relative number of judgments in favor 
 of the greater length of the filled space. Indeed, the writer 
 himself remarks on page 337, that ' when the spaces to be com- 
 pared are more than 10 cm. in length, the illusion does not hold 
 so steadily.' In fact, from about 10 cm. on, the illusion tends 
 to take the opposite direction from that which appeared below 
 that length and from that which appears in the visual field. 
 
 From the results of a few tentative experiments upon short 
 interrupted intervals, an analogy between our sensations of 
 touch and our perception of time is suggested. It is well 
 known that time of a given length, but interrupted at regular 
 intervals, seems within certain limits to be shorter than an equal 
 unbroken period. It has been found, however, that for very 
 short intervals the illusion changes in character, and such peri- 
 ods when interrupted at regular intervals appear to be longer 
 than an equal unbroken time.^ 
 
 For the purpose of investigating this matter experimentally 
 a number of cards were prepared, on each of which there was 
 marked off a short space defined by limiting lines. The spaces 
 formed a series and were respectively 8,9, 10, 11 and 12 mm. 
 wide, defined at each extremity by a pricked line one centi- 
 meter in length. The standard for comparison consisted of a 
 space 10 mm. wide which was broken at regular intervals by 
 five lines (Mill). Thirty series (150 judgments) were ob- 
 tained from each of the three subjects, B^ S and N. The 
 method of right and wrong cases was adopted. The cards to 
 be compared were presented in no regular order, but were 
 shuffled at intervals. A parallel experiment, thirty series for 
 each person, was also carried out, the standard in this ex- 
 periment being an unbroken space of 10 mm. long ( | | ). 
 
 The results of the two experiments are given in Table II. 
 The data for both experiments from each subject are placed one 
 below the other so that their comparison may be more easily 
 made. The upper line of the table gives the widths of the 
 unbroken spaces, or the variables which were compared with 
 
 ^Meumann, Phil. Stud., IX., p. 264, and XII., p. 127. 
 
560 
 
 ALICE ROBERTSON. 
 
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GEOMETRIC-OPTICAL ILLUSIONS IN TOUCH. 56 1 
 
 the two standards. The letters L, S, E, E or S, and D in the 
 second line, stand respectively for the judgments longer, shorter, 
 equal, equal or shorter, and doubtful. The number of judg- 
 ments of each kind is arranged in two lines for each subject, 
 the upper line giving the judgment of comparison with the 
 broken standard (Mill), the lower line, those with the un- 
 broken one (I I ). Thus, taking the first two lines which 
 represent the judgments given by the subject B^ we see that an 
 unbroken interval of 8 and 9 mm., when compared with the 
 standard, is thought to be shorter each time. The comparison 
 of an unbroken interval 10 mm. in length with an equal 
 broken interval gives 28 judgments of shorter, and the un- 
 broken spaces of II and 12 mm. give a predominance of the 
 judgments of shorter and equal. Contrasting these results 
 with those obtained from comparison with the unbroken stand- 
 ard, it will be seen that for this subject there is ample evidence 
 for an overestimation of intervals where the standard is 10 
 mm. in length. In these sets the 10 mm. and 11 mm. inter- 
 vals are the most instructive. Considering those for subject 
 TV, the 10 mm. unbroken interval is considered shorter than an 
 equal broken interval 17 times, and equal only 4 times; while 
 the II mm. interval is thought to be longer 18 times, and either 
 shorter or equal 12 times. When the same two intervals are 
 compared with the unbroken standard, the judgments of shorter 
 for the 10 mm. interval diminish, while those for 11 mm. show 
 almost no illusion. 
 
 In the case of subject S, the results are not so conclusive. 
 Unlike the first two subjects, he knew the purpose of the ex- 
 periment and felt, himself, that this knowledge was a difficulty 
 in the way of giving a ready judgment. When the unbroken 
 standard was used for comparison, there is a slight decrease in 
 the judgments of ' shorter ' and an increase of ' doubtful ' and 
 * equal ' for the 10 mm. interval; while for 11 mm. there is a 
 decided increase of judgments of 'longer' and 'equal' with 
 a decrease of ' shorter.' These results, when considered by 
 themselves, may be said to indicate a tendency toward the over- 
 estimation of interrupted intervals. Taken in connection with 
 those given by the two other subjects, there is a strong indica- 
 
562 ALICE ROBERTSON. 
 
 tion that in the tactual field a general law holds true, viz., that 
 long interrupted extents are underestimated, short ones overes- 
 timated.^ 
 
 The underestimation of interrupted extents by the tactual 
 
 Fig. 12. 
 
 sense is also shown in the comparison of squares which are 
 composed of either horizontal or vertical lines. When squares 
 similar to A and B (Fig. 12), whose sides are 10 cm. long, are 
 pricked in cardboard and are felt by running the hand as a whole 
 over them from right to left, or vice versa, then an illusion ap- 
 pears in the reverse direction from that perceived by sight. A 
 
 Fig. 13. 
 
 seems to lengthen so that it appears to be a rectangle whose 
 horizontal sides are longer and whose vertical sides are shorter. 
 On the other hand, B seems to shorten horizontally and to 
 lengthen vertically. Similarphenomenaoccurinthe figure which 
 
 1 This is in accord with the results of Professor Rieber, to be published in 
 the forthcoming volume of Harvard Studies. Dr. Rieber has very kindly 
 placed his results in outline at our disposal for comparison. 
 
GEOMETRIC-OPTICAL ILLUSIONS IN TOUCH. 
 
 563 
 
 represents alternate quadrants of interrupted and uninterrupted 
 extents (Fig. 13). When the hand is passed over such a figure, 
 the open or uninterrupted quadrant seems decidedly the larger. 
 While this may be taken as added proof that interrupted extents 
 are underestimated, yet the apparently very large size of the 
 open quadrant is probably due in 
 part to the inclusion by the hand of 
 much of the surrounding free space. 
 The arc through which the hand 
 sweeps in passing over the open 
 quadrant, not being well defined, 
 seems greater and may in reality be 
 greater than that through which it 
 passes when feeling the quadrant 
 filled with radiating lines. The 
 tactual illusion in this case is ana- 
 logous to that which is found in 
 sight, although in an opposite direc- 
 tion. For, while in sight the un- 
 interrupted quadrant seems smaller 
 than the filled one, this is doubtless 
 partly due to the fact that we com- 
 pare the arc of the ' filled ' quadrant, 
 i. e., the ends of the radiating lines, 
 with the chord of the arc of the ad- 
 joining open quadrant. The optical 
 illusion, then, is partly due to the 
 leaving out of some of the space 
 which belongs to the open quadrant. The tactual illusion, on 
 the other hand, is heightened by the taking in of additional 
 space. 
 
 2. Poggendorff Figure. — The Poggendorff figure has long 
 been a favorite subject for investigation as an optical illusion. 
 Many theories center about it and the closely related Zollner 
 figure, but so far as I know no attempt has been made to inves- 
 tigate the tactual phenomena connected with it. A few tenta- 
 tive experiments gave very constant and somewhat surprising 
 results. For whether the subject was or was not already ac- 
 quainted with the optical illusion which appears in this figure, 
 
 /, 
 
 Fig. 14. 
 
564 ALICE ROBERTSON. 
 
 whether he had or had not previously seen the figure which was 
 presented to him, the illusion was very apparent, but in a reverse 
 direction from that which appears to the eye. In the optical 
 illusion which this figure presents, the lower left half of the 
 oblique line appears to be too low, and not directly continuous 
 with the upper right half (Fig. 14). In the tactual illusion, on 
 the contrary, the lower left half of the oblique seems too high 
 to be considered a continuation of the upper right half of the 
 same line.^ Moreover, the amount of displacement in the tactual 
 illusion seems to be much greater than in the visual. It was, 
 therefore, thought worth while to conduct a set of experiments 
 for the purpose of making some quantitative determinations. A 
 figure was constructed having one part of the oblique line mov- 
 able, so that the amount of displacement could be easily meas- 
 ured. The verticals were placed 30 mm. apart, and the oblique 
 crossed them at an angle of 40°. At no time was the subject 
 permitted to see the figure. The sheet of cardboard upon which 
 it was constructed was placed before the subject so that his arm 
 was 2lX right angles to the transverse line over which his hand 
 should pass. It was found that if this line were slowly and 
 carefully traced with the finger-tips, the illusion either did not 
 appear or was very faint. In all cases it was required to judge 
 of the direct continuation of the two parts of the oblique line by 
 passing the flat of the hand over it, either alternately up and 
 down, or in one direction only, as the subject desired. As a 
 matter of fact, most persons settled into the one method of pass- 
 ing the hand from right to left downward over the line. 
 
 The experiment was conducted with four persons, B, S, D 
 and A. From each of these, five double series were obtained. 
 A descending series began with the transverse lines really con- 
 tinuous, although in no case did they seem so to the subject. 
 
 ' Professor Dresslar proposes an explanation for an illusion of displacement 
 of crossed lines which he considers may explain the optical illusion in the Pog- 
 gendorff figure, and which by implication, at least, seems to be intended as an 
 explanation of the tactual illusion in this figure. In my own experiments with 
 the Poggendorflf figure, the tactual illusion is shown to be in an opposite direc- 
 tion from that which appears in sight, and this fact would seem not only to 
 render Dr. Dresslar's proposed explanation inadequate for the illusion in touch 
 but also to throw doubt upon that offered for sight. See Amer. Jour, of Psy., 
 VI., p. 275. 
 
GEOMETRIC-OPTICAL ILLUSIONS IN TOUCH. 
 
 565 
 
 The movable side was then moved downward by steps of 2 or 
 2.5 mm. to the point where the two halves of the transverse line 
 seemed to the subject to be continuous, and then below that 
 
 Table III. 
 
 Average Thresholds and Mean Variation. 
 
 Subject. 
 
 Upper Ave. Thr. 
 
 Lower Ave. Thr. 
 
 General Average. 
 
 Mean Variation. 
 
 B 
 S 
 D 
 A 
 
 — 15.2 mm. 
 
 — 27.2 
 
 — 24.0 
 
 — 45-0 
 
 — 24.1 
 -30.1 
 
 — 30.1 
 
 — 50.3 
 
 — 19.6 
 
 — 28.6 
 
 — 27.1 
 
 — 47.7 
 
 4.6 
 I8.3 
 4.5 
 9.0 
 
 Aver. 
 
 — 27.8 
 
 — 33-6 
 
 — 30.7 
 
 6.6 
 
 point until the left side was clearly too low. An ascending 
 series retraced these steps to zero. Every such series, of course, 
 gave two thresholds. In tabulating the data a calculated equality 
 point was found of all the upper thres- 
 holds for the upper Hmit of continuity, 
 or upper threshold. In a similar way 
 the lower limit of continuity was found. 
 Table III. gives the results which were 
 obtained from each of the subjects 
 according to this method. In the table 
 the minus sign signifies the distance 
 of displacement downward, measured 
 along the line ab in Fig. 14. 
 
 It will be seen that the mean upper 
 threshold for all four subjects is — 27.8 
 mm., the mean lower —33-6 mm., 
 thus giving a general average of about 
 — 31 mm. That is, the lower left- 
 hand portion of the transverse line 
 must be moved downward 31 mm. on 
 an average before the two halves seem 
 to be continuous. If we contrast this 
 number with that which was obtained 
 by Burmester ^ in his investigation of 
 the optical illusion in the Poggendorff figure, we find a very 
 
 '^ Zeitschrift fur Psychologic, XII., p. 369. 
 
566 
 
 ALICE ROBERTSON. 
 
 wide difference in the amount of displacement which the two 
 senses of sight and touch reveal. With a breadth of 30 mm. 
 between the verticals and an angle of 40°, this investigator 
 found an average of —5.09 mm. as the amount of displace- 
 ment which was required to make the lines look continuous 
 when the figure was in a vertical position. 
 
 With some persons the two halves of the oblique line felt as 
 if they were parts of parallels, but the lower left-hand portion 
 seemed to be at a higher level than the upper right-hand por- 
 tion. It seemed to be the unanimous opinion of those who 
 experienced this illusion that the feeling of ' too high ' was due 
 in large part to the vertical parallels. These lines, it was 
 thought, guided the hand downward, below the point where it 
 should cross the space between the verticals, and in order to 
 reach the lower portion of the transverse line an actual upward 
 effort was necessary. In order to test the influence of the verti- 
 cals upon the illusion a second figure was made, omitting the 
 vertical lines altogether (Fig. 15). This, like Fig. 14, was 
 made with one side movable, so that the amount of displace- 
 ment could be measured. Five double series were obtained 
 from each of three subjects, B^ S and D, and the upper and 
 lower limits noted as before. The data are tabulated in Table 
 IV., and some very interesting results appear. Thus, in the 
 
 Table IV. 
 
 Tabids of Average Thresholds and Meax Variation When 
 Verticals are Omitted. 
 
 Subj. 
 
 Aver. Upper Thr. 
 
 Aver. Lower Thr. 
 
 General Average. 
 
 Mean Variation. 
 
 B 
 S 
 D 
 
 + 5-3 
 — 7.2 
 
 + .7 
 
 + 2.6 
 -8.3 
 -3-7 
 
 + 4.0 
 
 -7-7 
 — 1.5 
 
 3.95 
 3-49 
 
 2-5 
 
 case of B the direction of illusion changes, and the lines seem 
 continuous at some point above where they really are so. The 
 judgments given by subject D vacillate above and below the 
 zero point, and if we take the average of the two thresholds 
 to be the point where the two lines would seem continuous to 
 this subject, we find it to be — 1.5 mm. In this case, then, the 
 illusion is practically nothing. With subject S the threshold 
 
GEOMETRIC-OPTICAL ILLUSIONS IN TOUCH. 567 
 
 always falls below zero, on an average — 7.7 mm. From the 
 data it seems clear that in the absence of the verticals the 
 tactual illusion is very greatly weakened and almost nil. In 
 experimenting with a similar figure, Burmester found that the 
 optical illusion was much weakened and took an opposite 
 direction. This experimenter was at the same time his own 
 subject, so that it is possible that if he had operated with other 
 persons, individual differences would have appeared as they do 
 here. 
 
 An attempt was made to counteract the influence of the ver- 
 ticals by filling in the space between the end of the oblique lines 
 with lines running horizontally. The vertical parallels are of 
 course suggested by the ends of the horizontals, but since the 
 lines in the transverse direction are the more prominent, it was 
 thought that they would exert the greater influence and weaken 
 the illusion, or perhaps reverse its direction. Several figures 
 were made, in all of which the inclination of the oblique line 
 remained constant, 30°, but in which both the lengths of the 
 horizontal lines and their distance apart varied. The results of 
 experimentation indicated a decided weakening of the illusion, 
 but in no case was reversal obtained. 
 
 In whatever position the Poggendorff figure in its normal 
 form was laid, illusion was apparent. The amount of pressure 
 exerted, and the rapidity of movement, seem to have an effect 
 upon the amount of apparent displacement. Thus, in the case 
 of a figure in which the oblique lines were fixed, it was found 
 that, with hard pressure and rapid movement, the lower left- 
 hand line seemed too high ; whereas, with the same pressure 
 approximately, and slow movement, the two halves of the 
 oblique line seemed to be continuous. 
 
 Various theories suggest themselves as a partial explanation of 
 the tactual illusion which is exhibited by the Poggendorff figure. 
 That the verticals in some way influence the amount and direc- 
 tion of illusion in both sight and touch is obvious enough. To 
 some persons they seemed to exert a mechanical influence in 
 actually leading the hand astray, so that in passing downward 
 from the upper right-hand oblique to the lower left, an upward 
 effort is necessary in order to find the lower part of the line, 
 
56S ALICE ROBERTSON. 
 
 leading the subject to consider that that portion of the line is on 
 a higher level. An attempt was made to get tracings of the 
 path which the hand described in passing from one portion of 
 the oblique to the other. This was done by placing strips of 
 smoked paper in the path of a wire which was attached to the 
 hand. Thus, in one instance when the lower oblique was moved 
 downward 10 mm., in passing the hand from above downward 
 the two halves seemed continuous, while in passing from below 
 upward the lower left part of the oblique seemed too high ; 
 in these two instances, however, no difference can be detected 
 in the two tracings. That part of the curve which represents 
 the path of the hand between the verticals is almost a straight 
 line in both cases, and each is the normal and regular continua- 
 tion of the first part of the tracing. In another instance, the 
 two obliques were separated by a vertical distance of 18 mm. 
 To the subject the lines seemed continuous with both the upward 
 and downward movement, and the smoked paper tracings were 
 two perfectly even and smooth, almost parallel lines. In a third 
 instance the obliques were separated by a vertical distance of 
 23 mm. At this point they seemed continuous to the subject, 
 while the tracing shows many irregularities. These, however, 
 occur, not only in the space between the verticals, but through- 
 out the lines, and may be ascribed to natural tremors of the hand. 
 There is no evidence that there is an actual upward movement 
 of the hand corresponding to the effort which some subjects be- 
 lieved they felt. 
 
 Data obtained from figures similar to those used in these ex- 
 periments have afforded a basis for opposing theories of space 
 perception. The perspective theory of Thiery has already 
 been mentioned. He sees in the Poggendorff figure also a 
 definite perspective effect which is the cause of the apparent 
 shifting of the two halves of the oblique line. Professor 
 Wundt^ considers that the cause of the optical illusion in this 
 figure is the overestimation of the acute angles. The perspec- 
 tive effect, he maintains, appears only when one fixates a point 
 monocularly, at which time the displacement of the oblique 
 
 ^ ' Die geometrisch-optischeii Tiiuschungen,' Abhandl. d. konigl. sacks. 
 Gesellsch. d. JVissensc/i., XLII. 
 
GEOMETRIC-OPTICAL ILLUSIONS IN TOUCH. 569 
 
 lines disappears entirely. The ' asthetisch-mechanische ' theory 
 of Lipps/ offered first as an explanation of spatial form, has 
 later been applied to geometrical optical illusions. Among 
 other figures, this writer discusses the Poggendorff figure. He 
 applies to it his theory of the interaction of opposing forces, and 
 considers that it suggests the action of the two forces of gravity 
 and vertical extension. The oblique line represents a force ap- 
 proaching, but not attaining, verticality. In the struggle this 
 force is regarded as the primary activity, and as primary ac- 
 tivity is overestimated. 
 
 We have, then, at least three explanations of the phenomena 
 of the Poggendorff figure. It is here shown how the same 
 figure may give very different sensations to the skin. How are 
 the facts to be reconciled? If the optical phenomena of this 
 figure are due to the overestimation of the bending of the ob- 
 liques away from the vertical, according to Lipps, or if they are 
 due to an overestimation of the small angles, according to 
 Wundt, why should not these causes operate in the field of 
 touch, and, if they do, why should opposite effects be produced 
 upon the tactual sense? Likewise, no explanation for the op- 
 tical illusion in the ring segments satisfies the touch phenomena 
 in the same figures. Here again, perspective effects and the 
 overestimation of small angles are offered in explanation. But 
 the illusion persists in touch, when none is apparent to sight, 
 and when all perspective and almost all angle effect is lost com- 
 pletely. The data which are afforded by experiments in the 
 tactual field suggest a revision of the theories so far offered for 
 spatial illusions in general. These theories are in the main 
 founded upon optical phenomena. From what appears in the 
 tactual field it is reasonable to suppose that further study may 
 assist in elucidating this very complex and difficult problem. 
 
 ' ' Raumasthetik und geometrisch-optische Tauschuugen,' Schriften de? 
 Gesell.fiirpsy. Forschung, Vol. II., p. 295. 
 
 Ilfllrcfsity of Cailfflfoia 
 
 PsjKiiioioglcal Laborxtory, 
 
REPRINTED FROM 
 
 Vol. XII. No. 1. January, 1905. 
 
 THE 
 
 Psychological Review 
 
 EDITED BY 
 J. MARK BALDWIN HOWARD C. WARREN 
 
 Johns Hopkins University ^^° Princeton University 
 
 CHARLES IL JUDD, Yale University {Editor of the Monograph Series). 
 
 WITH THE CO-OPERATION FOR THIS SECTION OF 
 
 A. C. ARMSTRONG, Wesleyan University ; ALFRED BINET, Ecole des Hautes- 
 ^tudes, Paris ; W. L. BRYAN, Indiana University ; WILLIAM CALDWELL, Mc- 
 GiLL University; MARY W. CALKINS, Wellesley College; JOHN DEWEY, 
 Columbia University ; J. R. ANGELL, University op Chicago; C. LADD FRANKLIN, 
 Baltimore; H. N. GARDINER, Smith College; G. H. HOWISON, University of 
 California) P, JANET, College de France ; JOSEPH JASTROW, University of Wis- 
 consin; ADOLF MEYER, N. Y. Pathol. Institute; C. LLOYD MORGAN, University 
 College, Bristol; HUGO MONSTERBERG, Harvard University; E. A. PACE, 
 Catholic University, Washington ; G. T. W. PATRICK, University of Iowa; CARL 
 STUMFF, University, Bkulin; R. W. WENLEY, University of Michigan. 
 
 FROM THE UNIVERSITY OF CALIFORNIA PSYCHO- 
 LOGICAL LABORATORY 
 
 communicated by g. m. stratton 
 
 The Effect of "Verbal Suggestion upon the Estimation 
 OF Linear Magnitudes 
 
 By JOSEPH E. J5RAND 
 
 Late Assistant in the California l^syclioloiical Laborat.iry. 
 
 THE MACMILLAN COMPANY, 
 
 41 NORTH QUEEN ST., LANCASTER, PA. 
 66 FIFTH AVENUE, NEW YORK 
 
 Agent: G. E. STECHERT, London (2 Star Yard, Carey St., W. C, 
 Leipzig (Hospital St., 10); PariS (76rus de Reunea). 
 
 Ps^iihoiO'f'nsi !s^'' 
 
42 JOSEPH E. BRAND. 
 
 the lower one being 2.2 cm. in width, and the upper one i cm. 
 in width, having behind them backgrounds of the same black- 
 ness as the screens. Through the lower slot and against this 
 background were exposed the printed slips bearing the mottoes, 
 resting on a wooden ledge fastened to the back of the screen 
 just below the edge of the slot. On a similar ledge behind the 
 upper slot were exposed two white pegs .8 cm. in diameter and 
 long enough to have their ends hidden by the screen. These 
 pegs could be moved along the ledge, and hence adjusted for 
 various intervals between them. On the near side of the nearer 
 screen and just below the top, was a ledge on which the subject 
 moved little pegs similar to those just described, and thus repro- 
 duced his estimation of the standard interval. 
 
 Over the front of the farther screen was made to slide a 
 movable screen having a single horizontal slot through which 
 either of the two slots in the stationary screen could be exposed, 
 but not both together. Thus the subject saw either the motto 
 in the lower slot, or else the standard distance marked off by 
 the two white pegs appearing as rectangles i x .8 cm. in the 
 upper slot, or else both slots were altogether hidden. The dis- 
 tance from the subject's eye to the nearer screen was 40 cm., 
 and from the nearer screen to the farther was 80 cm. 
 
 The mode of operating the apparatus was sufficiently sim- 
 ple. The proper motto being in the lower slot, and the pegs 
 having been properly spaced in the upper, and both slots being 
 hidden by the movable screen, the operator, after due warning 
 to the subject, raised the screen one notch and exposed the 
 motto for two seconds ; then raised it a second notch and exposed 
 the standard interval for two seconds ; then dropped it one notch 
 and left the motto again exposed. The subject immediately so 
 placed his pegs on the ledge as to mark off his estimate of the 
 space interval, and the operator recorded the length so marked, 
 reading it from a scale hidden from the subject's vision by a 
 narrow strip of black paper projecting above the ledge. 
 
 I. First Set of Experiments. 
 In this first work only two subjects were engaged and a variety 
 of suggestion mottoes were used, viz., ^ Make short enough^ 
 
EFFECT OF VERBAL SUGGESTION. 43 
 
 * Make long enough,,' ' Don't make too long,' ' Don't make too 
 shorty' ' Make shorty' ' Make long,' a nonsense motto ' Zwffjvic 
 bgzx asye,' and a meaningless sentence ' Ltfe is real where.'' 
 These mottoes were printed in black capitals 1.2 cm. high on 
 white cardboard. 
 
 In groups A, B and C four standard lengths for estimatio 
 were used, 16, 22, 28 and 34 cm. In group D standards 
 of 24, 26, 30 and 32 cm. for subject C. and 12, 14, 18 and 20 
 cm. for subject Y. Long standards were used for subject C. in 
 this group because from examination of results in the preceding 
 groups it seemed that the long standards would give more defi- 
 nite results ; and since standards for this subject were changed, 
 it was thought advisable to change standards for the other sub- 
 ject also. Thus any possible difficulty from too long use of the 
 same standards was obviated. The four standards employed in 
 any group were given in succession with each motto, in an order 
 determined by lot, the order of succession of the mottoes being 
 changed for each day. A ' nonsense motto ' was used in order 
 that the tests without suggestion might be under conditions as 
 like as possible to the others, except for the suggestion itself. 
 
 Tables I. and II. give in detail the results of this investiga- 
 tion. Instead of finding the average lengths reproduced with 
 different mottoes it was deemed simpler to interpret the data by 
 aggregation. The number tabulated under a given motto for a 
 given day is therefore the sum of all the judgments taken that 
 day for that motto. As remarked above, the series in both tables 
 are arranged in four groups, which differ amongst themselves 
 in regard to the mottoes and standards used, and also in that a 
 month's interval elapsed between the work of group C and that 
 of group D. For convenience in examining the tables, totals 
 are given under each group for such columns as it is desirable 
 to compare. As all the mottoes are not used on all the davs, 
 only such days are included in forming the totals as make the 
 totals in the same horizontal line properly comparable. 
 
 An examination of these tables leads to some interesting 
 conclusions. First, we find by comparison of daily totals and 
 general totals, that the suggestion produces a definite, though 
 slight, effect. The results for ' Make short enough ' are in both 
 
44 
 
 JOSEPH E. BRAND. 
 
 Table I. 
 Based on 650 Judgments ; Subject, Miss C. 
 
 
 I 
 
 2 
 
 3 14 5 6 
 
 7 
 
 8 Vi 
 
 9 
 
 10 
 
 XI 
 
 
 6. 
 
 s 
 
 2 
 
 
 "0 
 >. 
 
 cd 
 
 Q 
 
 of 
 
 S 3 
 
 a 6 
 
 K - 
 
 tn u 
 
 Ai S. 
 
 H 
 
 V 3 
 M 
 
 5 bo 
 
 It 
 
 i2 a 
 
 V 
 
 
 n 
 
 Group A 
 
 ( Eight different 
 standards, 11-30 
 cm. long, were 
 used in this 
 group) 
 
 I 
 
 2 
 
 3 
 4 
 5 
 6 
 
 9 
 
 8 
 10 
 10 
 10 
 15 
 
 189 
 
 167 
 202 
 202 
 202 
 320 
 
 199 
 
 179 
 
 221.5 
 
 218 
 
 343-6 
 
 
 227 
 
 224.5 
 220 
 
 212.7 
 
 225 
 
 214 
 221.5 
 
 341.5 
 
 180.7 
 
 223.5 
 
 220 
 
 216 
 
 224 
 223 
 
 221 
 
 342.9 
 
 
 
 Sumof days3,4,5 
 
 3. 4, 5, 6... 
 
 3. 4, 6... 
 
 
 30 
 45 
 35 
 
 606 
 926 
 724 
 
 783.1 
 
 
 
 671-5 
 
 660.5 
 1,002 
 780.5 
 
 659-5 
 
 668 
 1,010.9 
 789.9 
 
 
 
 Group B 
 (Standards, 16, 
 22, 28, 34 cm.).. 
 
 2 
 3 
 4 
 
 II 
 16 
 
 24 
 24 
 
 248 
 322 
 
 5b8 
 660 
 
 
 
 
 
 
 
 259.2 
 302.5 
 584 
 650.7 
 
 258.3 
 305.2 
 597-6 
 680.3 
 
 Sum 
 
 
 75 
 
 1,818 
 
 
 
 
 
 
 
 1,796.4 
 
 1,841.4 
 
 Group C 
 (Standards. 16, 
 22, 28, 34 cm.)... 
 
 I 
 2 
 3 
 
 8 
 9 
 9 
 
 200 
 210 
 204 
 
 216.6 
 196.2 
 200.5 
 
 205 
 
 202.1 
 
 198.2 
 
 
 210.2 
 196-3 
 194.3 
 
 
 211.7 
 205.4 
 202.1 
 
 
 
 Sum 
 
 
 26 
 
 614 
 
 613-3 
 
 605.3 
 
 
 600.8 
 
 
 619.2 
 
 
 
 Group D 
 (Standards, 24, 
 26, 30, 32 cm.)... 
 
 I 
 
 2 
 
 3 
 4 
 
 6 
 10 
 
 7 
 6 
 
 170 
 276 
 206 
 162 
 
 279.1 
 
 209 
 
 165.6 
 
 279.1 
 
 2II.6 
 
 157-3 
 
 
 183.2 
 284.6 
 221.7 
 165.2 
 
 
 175-3 
 280.5 
 213.6 
 156.2 
 
 172 
 
 279 
 203.3 
 
 164.5 
 
 185.5 
 279.6 
 212.5 
 170 
 
 S. of days i, 2,3,4 
 2, 3, 4... 
 
 
 29 
 23 
 
 814 
 644 
 
 653-7 
 
 648 
 
 
 854-7 
 671-5 
 
 
 825.6 
 650.3 
 
 818.8 
 646.8 
 
 847-6 
 662.1 
 
 Total, (r&Z>( ex- 
 cept day i) 
 
 Total, A (except 
 daysi,2)C&Z? 
 
 Total, i9&Z> 
 
 
 49 
 
 100 
 104 
 
 1,258 
 
 2,354 
 2,632 
 
 1,267 
 
 1,253.3 
 
 
 1,272.3 
 2,457.5 
 
 — 
 
 1,269.5 
 2,455-7 
 
 2,615.2 2,689 
 
 cases greater than those for ' Make long enough ' ; the results 
 for ' Make long ' are greater than those for ' Make short ' for 
 subject C, and also greater for subject Y. in group Z), although 
 less in group B for this subject. Similarly, results for ' Don't 
 make too long ' are pretty uniformly greater than those for ' Don't 
 make too short' for subject Y., and also for subject C. in group 
 Z), but not for this observer in groups A and C. 
 
EFFECT OF VERBAL SUGGESTION. 
 
 45 
 
 Table 1 1. 
 Based on 598 Judgments ; Subject, Mr. Y. 
 
 
 I 
 
 2 
 
 3 1 4 
 
 S 
 
 6 
 
 7 
 
 8 
 
 9 
 
 10 
 
 II 
 
 
 0. 
 
 I 
 
 "o 
 
 
 3 ed - 
 
 Standard 
 (Sum). 
 
 Nonsense 
 Motto. 
 
 "3 
 
 V- 
 10 u 
 
 •'" I) 
 MA 
 
 1^ 
 
 -•a 
 
 1^ 
 
 ba 
 
 % 
 
 V 
 
 2 
 
 - tn 
 
 
 Group A 
 
 (Eight standards 
 11-30 cm. long). 
 
 I 
 
 2 
 
 3 
 4 
 
 9 
 10 
 10 
 15 
 
 189 
 202 
 202 
 320 
 
 176 
 188 
 186.5 
 297.6 
 
 
 197 
 191 
 289 
 
 176.5 
 188 
 190 
 293.8 
 
 179.7 
 192-5 
 194-5 
 
 190.5! 
 186.5 
 289.2 
 
 
 Sumofdavs, 2,3, 4 
 2, 3... 
 
 
 35 
 20 
 
 724 
 
 404 
 
 672.1 
 
 374-5 
 
 
 388 
 
 671.81 — 
 
 378 1387 
 
 666.2: 
 
 377 ' 
 
 
 Group B 
 (Standards 16, 22, 
 28. ^4) 
 
 I 
 2 
 3 
 4 
 
 21 
 22 
 
 19 
 20 
 
 534 
 538 
 514 
 
 524 
 
 
 
 
 
 
 
 503-3 
 499-9 
 499.8 
 487.2 
 
 487.8 
 491 
 500.9 
 488.5 
 
 
 
 Sum 
 
 
 82 
 
 2,110 
 
 
 
 
 
 
 
 1.QQ0.2 
 
 1,968.2 
 
 
 1 
 
 1 -^ " 
 
 
 Group C 
 (Standards 16, 22, 
 28, ^4) 
 
 I 
 2 
 
 3 
 
 II 
 II 
 9 
 
 320 
 278 
 198 
 
 283.9 
 252.5 
 176.5 
 
 276.8 
 248.8 
 178. 1 
 
 
 285.1 
 258-5 
 
 I75-I 
 
 287.8 
 255-6 
 172.2 
 
 
 
 
 
 Sum 
 
 
 31 
 
 7q6 
 
 712. Q 
 
 703-7 
 
 
 718.7I 
 
 715-6 
 
 
 i 
 
 
 
 
 Group D 
 (Standards 12, 14, 
 18 20") 
 
 I 
 
 2 
 3 
 
 6 
 6 
 6 
 
 98 94.7 
 
 90 86.6 
 102 94.9 
 
 91.7 
 86.3 
 
 94-3 
 
 
 i 
 92 1 
 
 89.8 
 94-31 
 
 94-3 
 88.1 
 91 
 
 92.2 
 85.6 
 
 Ql.d 
 
 92.8 
 i 92-4 
 
 
 
 Sum 
 
 
 18 
 
 290 276.2 
 
 272.3 
 
 1 
 
 276.1 
 
 273.4' 269.2' 280.2 
 
 Total, Cand D 
 
 Total, A (except 
 
 day I) CD 
 
 Total, B and D 
 
 1 
 
 49 
 
 84 
 100 
 
 1,086 
 
 1,810 
 2,400 
 
 1 989.1 
 
 976 
 
 
 994.8 
 1,666.6 
 
 
 989 j - ; - 
 
 1,655-2 — — 
 
 2,259.42,248.4 
 
 Since group B followed group A and group C followed 
 group B without gap, but a month elapsed between groups C 
 and Z?, and since the difference in the presumable effects of 
 the same mottoes occurs only between group D and the other 
 groups, we must conclude that the uniformity is too great to 
 admit of an explanation except by potency of the suggestion 
 from the mottoes. 
 
 Second, this suggestion-effect varies both according to the 
 individual to whom the suggestion is made, and also according 
 to circumstances. The disagreements just referred to as existing 
 between group D and the preceding groups is evidence upon the 
 
46 
 
 JOSEPH E. BRAND. 
 
 latter of these points. The data within these groups are reason- 
 ably self-consistent, showing that on almost every separate day 
 the same effect was produced, but that during the month's inter- 
 val the subject had gotten over into a condition such that the 
 difference between the effects produced upon him by two oppos- 
 ing formal suggestions was of opposite sign to what it was 
 earlier. 
 
 Third, the mere words ' long ' and ' short,' regardless of 
 their content, seem to affect the estimation under certain cir- 
 cumstances. This is illustrated by Table III., which gives the 
 sums for the mottoes containing the word ' short ' and the sums 
 for those containing the word ' long ' from group D of both 
 tables. 
 
 Table III. 
 
 Subject. 
 
 No. of Judgments. 
 
 Standard. 
 
 Mottoes Containing the Word 
 
 "Long. • 
 
 "Short." 
 
 c. 
 
 Y. 
 
 58 
 36 
 
 1628 
 
 580 
 
 1702.3 
 556.3 
 
 1644.4 
 542.6 
 
 From this table it will be seen that the total for mottoes con- 
 taining the word ' short ' is less in both cases than that for 
 mottoes containing the word ' long.' Similar totals from group 
 A give exactly opposite results for Table I., and neutral results 
 for Table II. (/. e., in the latter case the totals are about equal). 
 
 Now these results, taken as they are merely from the group 
 totals, may either be the result of chance, or they may be due 
 to the existence of a different attitude towards positive and nega- 
 tive suggestions, causing the subject at any given time to incline 
 to act in accordance with one and in opposition to the other ; or 
 they may be due to a tendency to be influenced by the mere 
 words ' short ' and ' long,' as said above. The likelihood of this 
 latter explanation led to the group of experiments which follow 
 under section 2. 
 
 Fourth, a motto which has interest for a subject seems to 
 give greater lengths in the reproduction than an uninteresting 
 one. The nonsense mottoes in group A (except for a single 
 day for subject Y.) give smaller totals than do the other mottoes, 
 which in this part of the experiment were not yet so familiar as 
 
EFFECT OF VERBAL SUGGESTION. 47 
 
 to lack interest ; while in groups C and D the motto ' Life is 
 real where,' which the subjects declared was much more empty 
 and uninteresting than the ' nonsense ' motto, and hence should 
 be taken as the criterion in these groups, gives smaller totals 
 than the averages for the suggestion mottoes, as show in Table 
 IV. 
 
 Table IV. 
 
 
 Mottoes with content. 
 
 
 
 (Average of columns 
 
 Mottoes without content, 
 
 Subject. 
 
 \^ and 9 of groups C 
 
 (Total of column 5 of 
 
 
 D, omitting row 
 
 same days.) 
 
 
 I of A Table I.) 
 
 
 C. (Table I.) 
 
 1270.8 
 
 1253-3 
 
 Y. (Table II.) 
 
 991.9 
 
 976.0 
 
 The indication of this comparison is of course very unsatis- 
 factory, but seems at least to warrant a special investigation on 
 this point. 
 
 2. Second Set of Experiments. 
 
 The apparent effect of the mere words ' long ' and ' short ' in 
 the first set of experiments led to the second set, in which the 
 mottoes used were only three in number, viz. : ' long,' ' short,' 
 and ' XXXX.' The apparatus differed from that described 
 above only in the substitution, for the pegs, of white paper 
 squares on a black screen, one square of the pair being on a 
 strip of black paper running in grooves behind a slot in the 
 screen, so that the adjustments, i. e., the various distances of 
 separation of the squares, were obtained by simply sliding the 
 strip along. Three standard distances were used, viz. : 17, 18 
 and 19 cm., being given in such order that each was preceded 
 by each of the others about an equal number of times, and each 
 of the three used an equal number of times on the same day. 
 Each of the mottoes was given an equal number of times with 
 each of the standards, in order determined by lot. The letters 
 of the mottoes were so spaced as to cover the same extent in 
 every case and so exclude the possibility of a difference due 
 to mere space contrast or assimilation. 
 
 Four subjects were employed, and the results were not very 
 uniform, two of the subjects showing no decided tendency 
 towards anything resembling a constant effect, while the other 
 
48 
 
 JOSEPH E. BRAND. 
 
 two subjects, showed a clear general constancy of considerable 
 difference throughout. The results for these two are given in 
 Tables V. and VI. 
 
 Table V. 
 Subject K. 
 
 Date. 
 
 Standard. 
 
 Times 
 Used. 
 
 Sum for 
 Standard. 
 
 Sum for 
 "I<ong." 
 
 Sum for 
 "Short." 
 
 Sum for 
 "XXXX." 
 
 Sept. i8. 
 
 17 
 18 
 
 19 
 
 3 
 3 
 3 
 
 51 
 54 
 57 
 
 47.8 
 53.6 
 
 54-8 
 
 48.4 
 52.4 
 56.2 
 
 48.3 
 53-9 
 58.0 
 
 
 162 
 
 156.2 
 
 157.0 
 
 160.2 
 
 Sept. 24. 
 
 17 
 iS 
 
 19 
 
 5 
 5 
 5 
 
 85 
 90 
 
 95 
 
 79-9 
 
 84.4 
 93.5 
 
 79.2 
 84-3 
 95-5 
 
 81.5 
 85.1 
 94-3 
 
 
 270 
 
 257.8 
 
 259.0 
 
 260.9 
 
 Sept. 25. 
 
 17 
 18 
 
 19 
 
 6 
 6 
 6 
 
 102 
 108 
 114 
 
 94-6 
 104.9 
 107.5 
 
 98.6 
 104.4 
 113.6 
 
 98.3 
 103.0 
 III. 7 
 
 
 324 
 
 307.0 
 
 316.6 
 
 3130 
 
 Sept. 26. 
 
 17 
 18 
 
 19 
 
 6 
 6 
 6 
 
 102 
 108 
 114 
 
 92.7 
 106.6 
 1 10.4 
 
 96.8 
 107.2 
 112.1 
 
 95-1 
 105.0 
 112. 9 
 
 
 324 
 
 309.7 
 
 316.1 
 
 313.0 
 
 Oct. 2. 
 
 17 
 18 
 
 19 
 
 6 
 6 
 6 
 
 102 
 108 
 114 
 
 94.1 
 101.8 
 III. 4 
 
 95.5 
 104.5 
 114.8 
 
 92.7 
 103.8 
 II3-7 
 
 
 324 
 
 307.3 
 
 314.8 
 
 310.2 
 
 Oct. 4. 
 
 17 
 18 
 
 19 
 
 4 
 4 
 4 
 
 68 
 72 
 76 
 
 58.1 
 67.2 
 
 72.7 
 
 62.3 
 65.7 
 73-4 
 
 60.6 
 68.6 
 73.2 
 
 
 216 
 
 198.0 
 
 201.4 
 
 202.4 
 
 Grand Total. 
 
 90 
 
 1620 
 
 1536.0 
 
 1564.9 
 
 1559.7 
 
 By examining Tables V. and VI. it will be seen that for 
 Subject K. the figures for the motto ' short ' are with two 
 exceptions greater than the figures for the motto ' long,' and 
 for subject M. the reverse is true, again with two exceptions. 
 In the daily totals, however, there are no exceptions. In spite 
 of the fact that the other two subjects gave neutral results, the 
 hypothesis that the words ' long ' and « short ' of themselves are 
 capable of influencing the estimation of distances seems well 
 
EFFECT OF VERBAL SUGGESTION. 
 
 Table VI. 
 
 Subject M. 
 
 49 
 
 Date. Standard. 
 
 Times 
 Used. 
 
 Sum for 
 Standard. 
 
 Sum for 
 "Long." 
 
 Sum for 
 "Short." 
 
 Sum for 
 "XXXX." 
 
 Sept. 5- 
 
 iS 
 19 
 
 6 
 6 
 
 108 
 114 
 
 108.3 
 123.2 
 
 103.2 
 II7.0 
 
 108.8 
 I16.8 
 
 
 222 
 
 231-5 
 
 220.2 
 
 225.6 
 
 Sept. 6. 
 
 17 
 18 
 
 7 
 5 
 
 119 
 90 
 
 II8.2 
 92.8 
 
 113.0 
 91.3 
 
 I18.5 
 
 86.1 
 
 
 209 
 
 211. 
 
 204.3 
 
 204.6 
 
 Sept. II. 
 
 18 
 19 
 
 8 
 6 
 
 144 
 114 
 
 144.6 
 I16.O 
 
 140.5 
 II7.8 
 
 141.7 
 112. 1 
 
 
 258 
 
 260.6 
 
 258.3 
 
 253.8 
 
 Sept. 13. 
 
 17 
 18 
 
 8 
 8 
 
 136 
 
 144 
 
 139.8 
 148.3 
 
 134.6 
 145-5 
 
 137.8 
 146.6 
 
 
 280 
 
 288.1 
 
 280.1 
 
 284.4 
 
 Oct. 7. 
 
 17 
 19 
 
 7 
 7 
 
 119 
 133 
 
 II7.3 
 130.2 
 
 116.0 
 134.3 
 
 119.0 
 
 134.7 
 
 
 252 
 
 247-5 
 
 250.3 
 
 253.7 
 
 Oct. II. 
 
 17 
 19 
 
 7 
 7 
 
 119 
 
 133 
 
 121. 
 136.7 
 
 115.0 
 132.5 
 
 117.4 
 138.0 
 
 
 252 
 
 257-7 
 
 247.5 
 
 2554 
 
 Oct. 14. 
 
 17 
 18 
 
 19 
 
 I 
 3 
 4 
 
 17 
 
 54 
 76 
 
 17.1 
 
 50.3 
 76.2 
 
 16.0 
 48.9 
 72.7 
 
 17.0 
 52.9 
 75.1 
 
 
 
 
 M7 
 
 143.6 
 
 137.6 
 
 145.0 
 
 Grand Total. 
 
 90 
 
 1620 
 
 1640.0 
 
 1598.3 
 
 1622.5 
 
 grounded, for in view of the discussion of the first group of 
 experiments we might expect that the suggestion effect would 
 be contrary in certain different subjects, and lacking in others. 
 Thus the influence of purely formal and arbitrary suggestion 
 seems even more clearly evidenced by this second group of 
 experiments than by the first. 
 
 Onlifcrsitf of California 
 
 Psyotiological laboratoni. 
 
?^ 
 
 REPRINTED FROM 
 
 Vol. XII. No. 1. January, 1905. 
 
 THE 
 
 Psychological Review 
 
 EDITED BY 
 J. MARK BALDWIN HOWARD C. WARREN 
 
 Johns Hopkins University ^^^ Princeton University 
 
 CHARLES H. JUDD, Yale University [Editor of the Monograph Series). 
 
 WITH THE CO-OPERATION FOR THIS SECTION OF 
 
 A. C. ARMSTRONG, Wesleyan University ; ALFRED BINET, £cole des Hautes- 
 6tudes, Paris ; W. L. BRYAN, Indiana University ; WILLIAM CALDWELL, Mc- 
 GiLL University; MARY W. CALKINS, Wellesley College; JOHN DEWEY, 
 Columbia University ; J. R. ANGELL, University op Chicago ; C. LADD FRANKLIN, 
 Baltimore; H. N. GARDINER, Smith College; G. H. HOWISON, University of 
 California ; P. JANET, College de France ; JOSEPH JASTROW, University of Wis- 
 consin; ADOLF MEYER, N. Y. Pathol. Institute; C. LLOYD MORGAN, University 
 College, Bristol; HUGO Mt^NSTERBERG, Harvard University; E. A. PACE, 
 Catholic University, Washington; G. T. W. PATRICK, University of Iowa; CARL 
 STUMPF, University, Berlin; R. W. WENLEY, University of Michigan. 
 
 FROM THE UNIVERSITY OF CALIFORNIA PSYCHO- 
 LOGICAL LABORATORY 
 
 communicated by g. m. stratton 
 
 Experiments on the Unreflective Ideas of Men 
 AND Women 
 
 By GENEVIEVE SAVAGE MANCHESTER 
 
 THE MACMILLAN COMPANY. 
 
 41 NORTH QUEEN ST., LANCASTER, PA. 
 66 FIFTH AVENUE, NEW YORK 
 
 Agbnt: G. E. STECHERT, London (2 Star Yard, Carey St., W. C); 
 Lbipzig (Hospital St., 10): Paris (76 rue de Rennes). 
 
 lirkrsitj si Caiifornii! 
 
[Reprinted from The Psychological Review, Vol. XII., No. i, Jan., 1905.] 
 
 VIII. Experiments on the Unreflective Ideas of Men 
 
 AND Women. 
 
 BY GENEVIEVE SAVAGE MANCHESTER. 
 
 In 1891, Professor Jastrow made a study ^ of the mental dif- 
 ferences of men and women, using as material, lists of one 
 hundred words each, written by men and women students in 
 his classes. These lists were written as rapidly as possible in 
 order that they should be natural and unreflective. From a 
 comparison of twenty-five men's lists, with an equal number of 
 the women's lists, he concluded that the feminine traits of mind 
 revealed by the study are : ' An attention to immediate sur- 
 roundings, to the finished product, to the ornamental, the indi- 
 vidual, and the concrete, while the masculine preference is for 
 the more remote, the constructive, the useful, the general, and 
 the abstract.' A few years later, a similar experiment was 
 made at Wellesley College. Miss Nevers,^ who made the 
 study, found that her results were strikingly different from 
 those obtained by Dr. Jastrow. Later, however, it was discov- 
 ered that for the most part, this difference in results was due to 
 a deviation in method, the instruction to write the lists as rap- 
 idly as possible, having been omitted by Miss Nevers. A repe- 
 tition of the experiment conforming closely to Professor Jas- 
 trow's procedure produced results which supported some of his 
 conclusions, but not all.^ 
 
 1 New Review, Vol., V, 1891, pp. 559 to 569. 
 
 2 Psychological Rbjvibw, 1895, pp. 361 to 367. 
 
 ^ Other experiments on the mental diflferences of men and women have 
 been carried on, though not along the lines suggested by Professor Jastrow. 
 Helen Bradford Thompson, in a study of the mental differences of men and 
 women came to the following conclusions {Psychological Norms in Men and 
 Women, Univ. Chic. Press, 1903, page 171) : " Women are decidedly superior 
 to men in memory, and possibly more rapid in associative thinking. Men are 
 probably superior in ingenuity. In general information and intellectual inter- 
 ests there is no difference characteristic of sex." For other references and 
 results V. Havelock Ellis' Man and Woman (Contemp. Science Series). 
 
 50 
 
 Onlverslty of California 
 
 Psyiiliological Laboratoi). 
 
51 GENEVIEVE SAVAGE MANCHESTER. 
 
 Preliminary to a further study of the mental differences of the 
 sexes, I have repeated Dr. Jastrow's experiment at the Univer- 
 sity of California. To get the required lists, all the men and 
 women in several classes in general psychology were given 
 blank sheets of paper on which were spaces for lOO words, the 
 writer's name, sex and the time required to write the list. The 
 only instructions given were to write at top speed and to avoid 
 writing words in sentences. From the large number of papers 
 received, three sets were selected, each set containing twenty-- 
 five men's lists and twenty-five women's. In selecting the lists, 
 the only requirements were that the lists should seem natural 
 and unreflective and that the same word should not appear 
 more than once in the same list ; that is, that each list should 
 furnish lOO different words. It is possible that this last require- 
 ment may have been a deviation from Professor Jastrow's 
 method. Upon inquiring, he wrote me that he was not certain 
 whether the Wisconsin lists had been kept free from repetitions 
 or not. With a very few exceptions, the same word does not 
 appear twice in any one paper in the California lists. Having 
 selected the lists, the words of each set were then separately 
 tabulated under the following twenty-five heads, the words 
 written by the men and women being kept apart in each set : 
 (i) animal kingdom, (2) verbs, (3) proper names, (4) adjec- 
 tives, (5) implements and utensils, (6) abstract terms, (7) wear- 
 ing apparel and fabrics, (8) vegetable kingdom, (9) building 
 and building materials, (10) parts of the body, (11) geograph- 
 ical and landscape features, (12) other parts of speech, (13) 
 miscellaneous, (14) interior furnishings, (15) meteorological and 
 astronomical, (16) mineral kingdom, (17) occupations and call- 
 ings, (18) conveyances, (19) stationery, (20) foods, (21) educa- 
 tional, (22) arts, (23) amusements, (24) mercantile terms, (25) 
 kinship. 
 
 After classifying each of the three sets separately, they 
 were then combined and the set thus obtained consisting of 
 seventy-five men's lists and seventy-five women's lists, was clas- 
 sified as the smaller sets had been. 
 
 The division of the words under the above twenty-five heads 
 follows the classification of Dr. Jastrow in order that the Cali- 
 
UNREFLECTIVE IDEAS OF MEN AND WOMEN. 52 
 
 fornia results might be comparable with those of Wisconsin, 
 although certain objections to the division might be urged. For 
 example it might be pointed out that the procedure of Dr. Jas- 
 trow does not admit of exact repetition, though this is essential 
 to a correct testing of results. No two experiments would 
 tabulate the words in the case of the twenty-five classes under 
 exactly the same heads. This difficulty arises from the fact 
 that some of the classes are vague. An illustration of this lack 
 of clear definition may be drawn from the class * interior fur- 
 nishings.' Many of the household articles that women use, are 
 of course, 'implements and utensils ' and just what household 
 articles should be classed as ' interior furnishings ' and what as 
 * implements and utensils ' is not clear. In case most of the 
 implements women use about their work are classed as ' interior 
 furnishings,' the preponderance of the men in the implement 
 group loses all its significance. The class ' foods ' is not clearly 
 to be distinguished from the ' animal,' ' vegetable ' and ' mineral 
 kingdom ' groups, since all foods can be classed under these 
 three heads. Here again there is a chance for words to stray. 
 The class ' educational ' is also exceedingly vague. Each per- 
 son who uses this system of classification will probably classify 
 under this group somewhat differently. The personal factor 
 will come in to an appreciable extent in each repetition of the 
 experiment and absolute uniformity of method will not be 
 secured. 
 
 These defects are easier to see than to remedy. If a classi- 
 fication free from them is possible, it must probably be made 
 along more strictly logical lines. The words would need to be 
 classified several times instead of once, selecting in each classi- 
 fication some one principle of division. 
 
 In two cases, I have made slight changes in Dr. Jasrrow's 
 terminology. For his term ' unique words,' unrepealed zvords 
 has been substituted, and for the term ' different words,' vocab- 
 ulary has been used. 
 
 In Table A the results of the California experiments are 
 given, together with those previously reported, arranged in 
 the order in which the experiments were performed. 
 
 To aid in comparing the results, they have been represented 
 
53 
 
 GENEVIEVE SAVAGE MANCHESTER. 
 
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UNREFLECTIVE IDEAS OF MEN AND WOMEN. 
 
 54 
 
 graphically by a system of vertical lines, the lengths of which 
 are proportionate to the numbers given in Table I. The con- 
 tinuous lines represent the number of words in each class used 
 by the men, the broken lines, the number of words written by 
 the women. 
 
 The order of arrangement of the classes in the diagram is, 
 of course, arbitrary. For convenience, the classes are arranged 
 in the order of their size, as obtained in the results of Professor 
 Jastrow's men. The series begins with the class ' animal king- 
 
 'S«6 
 
 £40 
 
 TABLE I. 
 
 University of Wisconsin. 
 
 Continuous lines Men. 
 
 SroJfcn lines Women. 
 
 u 
 
 U—k. 
 
 fn 
 
 It 
 
 I i 1^1 lit 3 
 
 ^ .? 
 
 fs: ^ 
 
 
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 ^ ^ 
 
 dom,'to which the men of the Universit}' of Wisconsin contrib- 
 uted the largest number of words, and ends with ' kinship,' the 
 class to which they gave the smallest number of words. This 
 order is kept for the women of the Wisconsin lists and for all 
 the subsequent lists. 
 
 Turning now to Table I. to review the com; arison of the 
 Wisconsin men and women, it is seen at a glance that the women 
 greatly preponderate over the men in the class of ' wearing ap- 
 parel and fabrics,' ' interior furnishings ' and ' foods ' ; to a less 
 degree in the classes ' educational,' ' arts ' and ' amusements.' In 
 
55 
 
 GENEVIEVE SAVAGE MANCHESTER. 
 
 mentioning terms denoting objects in the ' animal kingdom,' ' ad- 
 jectives,' 'abstract terms' and 'implements and utensils,' the 
 men exceed the women. Numerous other variations are shown, 
 but these are the most striking. 
 
 A comparison of these results with those obtained by the Cali- 
 fornia experiments discloses the fact that, while there is general 
 agreement in several interesting particulars, there is nothing 
 that can be called complete corroboration of the conclusions 
 Professor Jastrow drew. ^ A prominent characteristic to be 
 
 180- 
 
 TABLE II 
 Uninrsity of California , stt 1. 
 
 ConHnuous lines /Hm. 
 
 , Broken linet Women. 
 
 I 
 
 •It 
 
 Is 
 
 •^1 
 
 ? >^ 
 
 
 
 <•' W 
 
 
 J t* 
 
 «i 
 
 f5 1 1 ^ 
 
 
 
 
 ^ 
 
 .? ^ ?. '^ 
 
 
 tj ij k 
 
 
 noted in the California experiments is the absence of the marked 
 disparity between the men and women which the Wisconsin 
 record shows. In the class * wearing apparel and fabrics,' the 
 California women clearly exceed the California men but in a 
 less degree than the Wisconsin women exceed the Wisconsin 
 men. (Compare Tables II., III., IV. and V. with Table I.) 
 
 The same relation holds for the class ' interior furnishings ' ; 
 but in the case of ' foods,' one of the three classes in which the 
 
 ^The fact that there are no men's lists in the Wellesley material is an 
 obvious drawback in comparing them with Wisconsin and California lists and 
 for that reason they will, for the time, be left out of account. 
 
UNREFLECTIVE IDEAS OF MEN AND WOMEN. 
 
 56 
 
 Wisconsin women markedly exceeded the Wisconsin men, the 
 result differs from that obtained by Professor Jastrow. In one 
 of the California sets, the women exceed the men slightly (see 
 Table II.), while in the other two sets, the men are slightly 
 in advance of the women. 
 
 The California lists agree with the Wisconsin lists in that the 
 women exceed the men in the classes ' educational,' ' arts,' and 
 ' amusements ' ; but as before, the California men and women 
 differ less from each other than the Wisconsin men and women. 
 
 3S0T 
 
 300 
 
 240 
 
 l»0- 
 
 ISO 
 
 60- 
 
 TABLE m. 
 Unhersity of California, Sei S. 
 
 Continuous iines Men. 
 
 Broken lines Women. 
 
 % 
 
 ^ 
 
 5 ., J 
 
 "S 5 V) 
 
 —.VIA 
 
 :s: f>, ^ 
 
 «< «s 3; 
 
 
 1!| 
 
 •Si?.*? 
 
 i_ii 
 
 I! il 
 
 * !■ 1. 
 
 
 -u. 
 
 5 ,0 
 
 $$i=i ^^e^k 
 
 
 ? < ^ 
 
 .^ 
 •$ 
 
 
 The notable ratios in which the Wisconsin men exceeded their 
 women classmates in terms belonging to the classes ' animal 
 kingdom,' ' proper names ' and ' adjectives ' do not hold for the 
 California lists. The California sets all agree with the Wis- 
 consin lists in that the men lead the women in every case in 
 mention of 'verbs' and 'implements and utensils.' A general 
 agreement of both Wisconsin and California results is to be 
 found in the fact that both men and women drew the larger part 
 of their words from the classes arranged on the left half of the 
 tables, while the classes to the right, such as ' educational,' 
 
SI 
 
 GENEVIEVE SAVAGE MANCHESTER. 
 
 * amusements,' ' mercantile terms ' and especially ' kinship ' fur- 
 nish comparatively few of the surface ideas. 
 
 In the Wisconsin lists, Dr. Jastrow found that the vocabulary 
 of the men was greater than that of the women. The same re- 
 sult was obtained in all three of the California sets. In Table 
 VI. the results of this part of the experiment are tabulated, the 
 results of the Wisconsin and Wellesley experiments being 
 included. ^ 
 
 lao 
 
 \1 
 
 il 
 
 TABLE IV, 
 University of CatiforniaSdi^. 
 
 Continuous lines . 
 3rokeft 7ir:ss. . . 
 
 . . . Men. 
 Women. 
 
 I I 
 I 
 
 I I 
 
 J ' 
 
 I I 
 
 \l \ ' It 
 
 55 
 
 5 
 
 i. ft. «^ 
 
 I I 
 
 I- * 
 
 i:'*^ 3^'5 r^^ ? 
 
 •f'^' § 
 
 5 
 ,,5 
 
 i ^ ttj 
 
 
 J5 «2 
 
 
 ^1 
 
 
 §• ^ -5 
 
 
 -6 -5 
 
 ^ ^ Q <0 "o k 
 
 •4 S 
 §1 
 
 
 
 1^ 
 
 .5. 
 
 A study of this table shows that in each of the five sets, the 
 men have used a larger percentage of different words than the 
 women of the same set. In set II. of the California series, how- 
 ever, the women exceed the men of set I. in vocabulary. It is 
 to be remarked that the women in all three of the California sets 
 and also in the Wellesley set, exceed the Wisconsin men in 
 vocabulary. It is also to be noted that the difference between 
 the vocabularies of the Wisconsin men and women is considera- 
 bly greater than that between the California men and women. 
 
 ' The column headed ' percentages ' indicates the ratio of the vocabulary to 
 the total number of words written. 
 
UNREFLECTIVE IDEAS OF MEN AND WOMEN. 
 
 5S 
 
 The vocabulary of the Wisconsin men is lO per cent, larger 
 than that of their women classmates, while, in no case, does the 
 vocabulary of the California men exceed that of the California 
 
 90» 
 
 726- 
 
 itO 
 
 I i 
 
 I 
 
 1 
 
 lJjl. 
 
 TABLE V. 
 
 Oft/versify of Csfifornia, Canbined Sets. 
 
 Cmtinusui H.^es Men. 
 
 Braken liaai . Wame.t. 
 
 !« e 
 
 ' M V* h 
 
 I \ 
 
 I il 
 
 IJi. 
 
 
 •^ ii' K 
 
 
 St V ^o -^-r 4^ 
 
 pi 
 
 
 
 ^ js> ■•■> 
 
 
 ^ ^ 
 
 i^ U s:^ ^^ < 
 
 .sj' 
 
 "5 
 
 
 $ ^ 
 
 k 1^ 
 
 women more than 4 per cent. In every set, both the men and 
 women in the California experiment use larger vocabularies 
 than either the men or women of Wisconsin. It would, of 
 
 Table VI. 
 
 
 Unrepeat 
 Men. 
 
 ed Words. 
 Women. 
 
 Vocabulary. 
 
 Percentages. 
 
 
 Men. 
 
 Women. 
 
 Men. 
 
 Women. 
 
 Wisconsin 
 
 746 
 1000 
 117a 
 1079 
 1975 
 
 520 
 
 949 
 
 1079 
 
 978 
 
 1950 
 868 
 
 1376 
 1471 
 1583 
 1489 
 
 3119 
 
 II23 
 1397 
 1509 
 1407 
 3C48 
 1306 
 
 55 
 
 58 
 
 63-32 
 
 59-56 
 
 41.58 
 
 44-9 
 
 55-9 
 
 60.36 
 
 56.28 
 
 40.64 
 
 52.25 
 
 California Set I 
 
 California Set II 
 
 California Set. Ill 
 
 Combined Calif. Set. 
 Wellesley 
 
 course, be unwarranted to conclude from these results (though 
 the thought is at least suggested) that the men and women of 
 California have more diversified interests that those of Wiscon- 
 
59 GENEVIEVE SAVAGE MANCHESTER. 
 
 sin, and that the men and women of California differ from each 
 other less than the men and women of Wisconsin. Only one 
 set of lists is given here for the University of Wisconsin, and 
 additional sets might change the proportions materially. The 
 matter of the treatment of plurals may account in great part for 
 the larger vocabularies obtained in the California experiments. 
 I have in all cases counted the singular and plural of the same 
 idea as two different words. The justification for this is to be 
 found along psychological rather than etymological lines. 
 Etymologically, the words horse and horses are practically the 
 same, but the mental picture, or idea, corresponding to each is 
 different. If Professor Jastrovv did not make this distinction, 
 but counted the singular and plural forms of an idea as the same 
 word, the vocabularies in the Wisconsin study would be corres- 
 pondingly low. 
 
 That the men exceed the women in vocabulary in each of the 
 five sett?, is significant, even if the superiority on the part of the 
 men is slight. It should be remembered that in the combined 
 California set, the total number of words was three times as 
 large as in the other sets. It is to be noted, further, that not only 
 the percentage of difference, but the absolute difference between 
 the vocabularies of the men and women is greater in the 2,500- 
 words sets than in the 7,500-word set. In the smaller sets, the 
 difference varies from two per cent, to a little more than three 
 per cent, while in the large set, the difference is leveled to one 
 per cent. It seems likely that if the number of lists were in- 
 definitely increased, the difference in vocabulary between the 
 men and women would diminish regularly as the limits of the 
 language were approached. 
 
 Leaving now any further comparison of the California re- 
 sults with those obtained by other experiments, a more profita- 
 ble field for study lies in the examination of the cumulative re- 
 sults of the experiments at Wisconsin and California, in order 
 to discover in what features, if any, all of the results agree. If 
 this study is to disclose any real differences between the unre- 
 flective ideas of the sexes, such differences should be evident in 
 all of the sets of lists, or at least in a pronounced majority of 
 them. The most significant differences, then, revealed by these 
 
UNREFLECTIVE IDEAS OF MEN AND WOMEN. 
 
 60 
 
 experiments, will be those which appear in every one of the 
 four sets. 
 
 To indicate the agreement or disagreement of the different 
 sets as regards the classes of words used Table VII. was 
 prepared. 
 
 Table VII. 
 + Me;n Lead. — Women Lead. 
 
 Calif. Comb. 
 
 Animal kingdom 
 
 Verbs 
 
 Proper names 
 
 Adjectives 
 
 Implements and utensils 
 
 Abstract terms 
 
 Wearing apparel, fabrics 
 
 Vegetable kingdom 
 
 Buildings, building materials 
 
 Parts of body 
 
 Geographical, landscape 
 
 Other parts of speech 
 
 Miscellaneous 
 
 Interior furnishings 
 
 Meteorological, astronomical 
 
 Mineral kingdom 
 
 Occupations , 
 
 Convey ances 
 
 Stationery 
 
 Foods 
 
 Educational 
 
 Arts, sciences 
 
 Amusements 
 
 Mercantile terms 
 
 Kinship 
 
 Wis. 
 
 Calif. I. 
 
 Calif. II. 
 
 Calif. III. 
 
 + 
 
 — 
 
 + 
 
 + 
 
 + 
 
 + 
 
 + 
 
 -L. 
 
 + 
 
 — 
 
 — 
 
 + 
 
 + 
 
 — 
 
 — 
 
 
 
 + 
 
 + 
 
 + 
 
 + 
 
 _L 
 
 + 
 
 + 
 
 
 
 + 
 
 — 
 
 + 
 
 — 
 
 
 
 + 
 
 + 
 
 + 
 
 + 
 
 + 
 
 — 
 
 
 
 + 
 
 — 
 
 + 
 
 + 
 
 
 
 -4- 
 
 + 
 
 + 
 
 + 
 
 + 
 
 + 
 
 
 
 
 
 + 
 
 + 
 
 + 
 
 + 
 
 + 
 
 + 
 
 + 
 
 + 
 
 — 
 
 — 
 
 
 
 
 
 + 
 
 + 
 
 — 
 
 — 
 
 — 
 
 + 
 
 + 
 
 + 
 
 — 
 
 
 + 
 
 
 + 
 
 — 
 
 — 
 
 + 
 + 
 
 + 
 + 
 
 + 
 
 + 
 + 
 
 + 
 + 
 
 + 
 
 In this table, the classes in which the men excelled the 
 women in the number of words written are marked by a plus 
 sign, while the classes in which the women led are indicated by 
 a minus sign. 
 
 A review of the results of the classification into the twenty- 
 five groups, shows a rather remarkable agreement in the five 
 sets tabulated in Table VII. Of the twenty-five classes, eigh- 
 teen show an agreement, either in all five cases or in four cases 
 out of five. In the three classes in which the men lead most 
 pronouncedly, namely, in ' verbs,' ' implements and utensils ' and 
 * occupations,' the notion of action is prominent. In the 
 classes in which the women lead, such as ' adjectives,' ' wear- 
 ing apparel and fabrics,' 'interior furnishings' and 'buildings 
 
6l GENEVIEVE SAVAGE MANCHESTER. 
 
 and parts of buildings,' no such notion is evident. On the con- 
 trary, these show a preference for things at rest. 
 
 Running through all, or nearly all, of these agreements in 
 results, there appears, beside the notion of action as contrasted 
 with inaction, another element. In the cases in which the men 
 lead, time is an essential factor ; in the cases in which the 
 women lead, space is the more prominent consideration. While 
 the time and space conceptions are closely allied to the notions 
 of action and inaction, they seem, nevertheless, to be not alto- 
 gether identical. A further inference may be drawn from the 
 cases in which there is agreement in all five sets. The fact 
 that the men throughout draw a large percentage of their words 
 from such classes as 'implements and utensils,' 'occupations,' 
 and ' verbs ' than the women do, and from the fact that the 
 women lead throughout in the classes ' wearing apparel and 
 fabrics,' ' buildings and building materials,' and ' interior fur- 
 nishings,' it may be inferred that the unreflective ideas of both 
 men and women concern the objects with which they are famil- 
 iar and in which they have considerable interest. That the 
 classes ' implements and utensils ' and ' occupations ' are of 
 special masculine interest, will probably not be questioned, but 
 such an interpretation of the verb class needs justification. This 
 justification is found in the character of the verbs used. In a 
 ver}^ large percentage of the cases in which men use verbs, 
 these verbs are suggestive of action in the field of men's es- 
 pecial interest. 
 
 To make this clear, two lists of verbs are submitted, one se- 
 cured from three men's papers and the other from three women's, 
 the lists being taken at random in both cases. Such words as 
 ' address ' and ' telegraph,' classed here as verbs, may also be 
 nouns. In such cases the context was taken as a guide in de- 
 termining the sense in which the writer used the word. The 
 lists follow : 
 
 A. (i) address, (2) telegraph, (3) fall, (4) rise, (5) call, (6) 
 forget, (7) ride, (8) play, (9) ringing, (10) reading, (11) study- 
 ing, (12) work, (13) play, (14) tick. 
 
 B. (i) shoot, (2) tick, (3) twitch, (4) cure, (5) hit, (6) miss, 
 (7) aim, (8) blow, (9) shoot, (10) sail, (11) hoist, (12) lift, (13) 
 pump, (14) rush, (15) study, (16) judge. 
 
UNREFLECTIVE IDEAS OF MEN AND WOMEN. 62 
 
 The first series of verbs was taken from women's lists, the 
 second from men's. The masculine character of the second 
 series is unmistakable and was so judged by several persons to 
 whom the lists were read without disclosing the actual source of 
 each group. 
 
 With this further knowledge of the verbs used, it seems safe 
 to say that the evidence justifies the statement that the un- 
 reflective ideas of men are controlled by the familiar and inter- 
 esting acts and objects of their lives. Similiarly, the classes 
 ' wearing apparel and fabrics,' and ' interior furnishings,' are 
 recognized categories of peculiar feminine interest. It might 
 be suggested, however, that buildings and building materials 
 are not distinctly familiar and interesting to women. The ob- 
 jection falls when the character of the words drawn from this 
 class is known. The words used were names of particular 
 buildings and parts of houses, such as court house, church, 
 gate, door, floor, fence, steps, marble. There is scant men- 
 tion by the women of such distinctive building materials as 
 bricks, mortar, cement and stone. 
 
 Just why women should exceed men in the classes ' arts,' 
 and ' educational ' is not evident, but taking the cue from the 
 former cases, it seems that it might be because these classes of 
 objects are more familiar to women than to men and of rela- 
 tively more importance to them. Though men are the chief 
 creators of art, women are more familiar with the ordinary art 
 products, such as pictures and musical compositions. Simi- 
 larly in educational matters, the women were probably more 
 impressed with the parts of the educational system, such as lec- 
 tures, texts and examinations, owing, perhaps to the fact that 
 many of them were preparing to become teachers. 
 
 That the women lead in the category of amusements, is 
 probably due to the fact that women, as a class, have more 
 leisure than men. With the time to enjoy amusements of vari- 
 ous kinds, women indulge more in them. Hence these things 
 are more familiar to women than to men and come more read- 
 ily to mind when there is a call for a rapid gathering of ideas. 
 
 Leaving now the cases where there is an agreement 
 throughout all five sets, the agreements which appear in four 
 
63 GENEVIEVE SAVAGE MANCHESTER. 
 
 sets out of five deserve a word. In the classes ' animal king- 
 dom,' ' abstract terms,' ' parts of the body,' ' miscellaneous,' 
 ' mineral kingdom ' and ' other parts of speech,' the men exceed 
 the women in four sets out of five. The mention of objects be- 
 longing to the ' animal kingdom ' is plentiful in the lists of both 
 men and women, the difference between the number of times 
 such words are written by men and women being, on the whole, 
 not very large, but the fact is notable that in all cases, but one, 
 the sex naturally most familiar with the various members of the 
 ' animal kingdom ' is the one which leads in this class. In the 
 class ' abstract terms,' a similar condition prevails. While the 
 total numerical lead of the men over the women is not great, it 
 is, nevertheless, to be found in four cases out of five. That 
 men have more interest and training in mathematical, physical 
 and philosophical abstractions, might account for this difference. 
 The significance of the men's lead in mention of ' other parts of 
 speech ' is not clear. In the classification used, this term em- 
 braces conjunctions, prepositions, interjections, pronouns and 
 adverbs. Since the class was not subdivided, it is impossible 
 to tell in which of the four parts of speech the men markedly 
 excel. As they lead in verbs, it might be expected that they 
 would lead in adverbs. So too, it might be expected that men 
 would lead in prepositions and conjunctions since these deal 
 with abstract relations. 
 
 Men also lead the women four times out of five in mention 
 of ' parts of the body.' Just what, if anything, this implies, I 
 have not determined, though it may be that the greater impor- 
 tance of the parts of a man's body, as tools for his daily use, 
 keeps the conceptions of them more constantly in his mind. 
 
 That men lead in the class ' miscellaneous ' may mean any 
 one of several things. If the other groups in the classification 
 happened to be more adapted to catch the surface ideas of women 
 than those of men, the ' miscellaneous ' class would be corre- 
 spondingly large for the men. Another explanation of the 
 men's superiority here might lie in the fact that men are inter- 
 ested in a greater number of objects and activities. 
 
 The lead of the men in the ' mineral kingdom ' is probably 
 due to the fact that they carve and chisel, mine and build, while 
 women ordinarilv do not. 
 
UNREFLECTIVE IDEAS OF MEN AND WOMEN. 64 
 
 ' Conveyances ' might have been discussed under the head of 
 * amusements,' as most of the words in this class seemed to be 
 of that general character. 
 
 That the women in all of the California sets lead in the men- 
 tion of adjectives seems significant. It has been found in the 
 classes discussed before that the surface ideas of men concern 
 action, the tools used in the performing acts, and the differentia- 
 tions of particular acts into occupations; that is, their ideas are 
 related to construction. The women, on the other hand, excel 
 the men in the mention of articles of dress, house fittings, parts 
 of houses, particular buildings and art products. There seems 
 to be a real principle of difference herein the general character 
 of the words written by the men and those written by the women. 
 Men speak of the process of creating, women of the thing 
 created. This is the same conclusion reached by Dr. Jastrow. 
 
 In view, then, of this tendency of the feminine mind toward 
 things, rather than the doing of things, it seems natural that 
 women should be more familiar with the qualities of things than 
 men are. This preponderance of adjectives in the women's 
 lists seems to bear out this supposition. 
 
 In the mention of terms of kinship, it is of interest to note 
 that both the men and the women draw very sparingly from this 
 class. This fact seems rather in opposition to the hypothesis be- 
 fore advanced that the surface ideas are of things familiar and 
 interesting, for of course one's kindred are usually the persons 
 seen oftenest and considered of greatest importance. It is 
 probable that unconscious or even conscious selection played a 
 part here. It is very likely that the persons writing the lists 
 considered this work a sort of official act since the papers were 
 to be returned to an instructor, and they would naturally refrain 
 to a certain extent, from speaking of parents and other relatives. 
 The very attitude the mind took in performing the task would 
 inhibit ideas drawn from the family life. 
 
 In the classes which have not yet been discussed, ' proper 
 names,' ' meteorological and astronomical terms,' 'stationery,' 
 ' foods ' and ' mercantile terms,' there is not enough regularity 
 to warrant the drawing of any conclusions. In the class ' proper 
 names,' it would be expected that the women would lead con- 
 
65 
 
 GENEVIEVE SAVAGE MANCHESTER. 
 
 siderabl}', since they show a preference for the concrete, rather 
 than the abstract, but in two sets out of five, the men are ahead. 
 Again, the natural expectation would be that men would write 
 many more astronomical and meteorological terms than women, 
 but in this class the men lead in only three cases out of five. 
 Oddly enough, the men on the whole, in the California sets, 
 lead slightly in foods, and the women in mercantile terms, very 
 different results from those obtained by Dr. Jastrow. 
 
 Coming now to the last feature to be examined, namely, the 
 time required to write the lists, it is seen from Table VIII. that 
 the average time for the women of California is 5 minutes and 
 39 seconds. The average time for the men of California is 5 
 minutes and 47 seconds. 
 
 Table VIII. 
 
 
 Average for Men. 
 
 Average for Women. 
 
 Average for Men 
 and Women. 
 
 
 6 min. 2 sec. 
 6 min. 17 sec. 
 5 min. 2j^ sec. 
 
 5 min. 47 sec. 
 
 6 min. 
 
 5 min. 55 sec. 
 
 5 min. 2 sec. 
 
 5 min. 
 
 5 min. 39 sec. 
 
 5 min. 8 sec. 
 
 6 min. i sec. 
 
 California I 
 
 California II 
 
 California III 
 
 Wellesley 
 
 6 min. 6 sec. 
 5 min. 2 sec. 
 
 Combined Calif. ... 
 
 
 As Professor Jastrow does not give the average time for each 
 sex separatel}'", and as there are no men in the Wellesley list, 
 these sets are not available for this comparison. 
 
 In each of the California sets, the time the women required 
 to write the lists is slightly less than that of the men. This 
 may mean, either that the women associate more quickly, or 
 that they write more rapidly. That each student kept his own 
 time renders these results less trustworthy than they would 
 otherwise have been. 
 
 Having now presented the evidence at hand, it only remains 
 to review the differences in the unreflective ideas of the sexes 
 as suggested by these experiments. 
 
 From the results of the classification into the twenty-five 
 groups, the following general statements in regard to the surface 
 ideas of men and women may be made : 
 
 I. The surface ideas of both men and women pertain to ob- 
 jects which are familiar and interesting. 
 
UNREFLECTIVE IDEAS OF MEN AND WOMEN. 66 
 
 2. The dynamic aspect of objects is more attractive to men, 
 while the static or completed aspect appeals more to women. 
 
 3. Time as a factor enters more largely into the surface 
 ideas of men ; space is more often a prominent feature of the 
 surface ideas of women. 
 
 4. Men make a greater use of abstract terms, while women 
 show a preference for the concrete and for descriptive words. 
 
 From the tabulation of the words used into unrepeated words 
 and vocabulary, it is found that the range of the surface ideas 
 of men, as a group, is slightly greater than that of women. 
 
 From the examination into the average time required for 
 writing the lists, it is found that women are able to write one 
 hundred associated surface ideas in somewhat less time than 
 men. 
 
 All of the specific tendencies above mentioned seem to give 
 concurrence to a general principle of difference between the 
 sexes. The surface ideas of men are extensive rather than 
 intensive, while the opposite is true of women. This conclusion 
 is supported, not only by the fact that men show a preference 
 for abstract terms, for action and for the time idea, while women 
 prefer the concrete, the completed object and space relations, 
 but also by the facts that men have a greater range of surface 
 ideas than women, and to a certain extent by the fact that 
 women have their reflective ideas more at hand, as shown by 
 their shorter list-time. Men are interested in far-reaching rela- 
 tions existing between things ; women give more attention to the 
 minute analysis of things themselves.' 
 
 ^ The M3S. of these Studies were received October 17, 1904. — Ed. 
 
 OnlYersit) of California 
 
 Psycliolopal Laboratory. 
 
REPRINTED FROM 
 
 VOL. XII. No, 5. September, 1905. 
 
 THE 
 
 Psychological Review 
 
 EDITED BY 
 J. MARK BALDWIN HOWARD C. WARREN 
 
 Johns Hopkins University '^^^ Princeton University 
 
 CHARLES H. JUDD, Yale University [Editor of the Monograph Series). 
 
 WITH THE CO-OPERATION FOR THIS SECTION OF 
 
 A. C. ARMSTRONG, Wesleyan University ; A1,FRED BINET, Ecole des Hautes- 
 fiTUDES, Paris; W. L. BRYAN, Indiana University; WILLIAM CALDWELL, Mc- 
 GiLL University; MARY W. CALKINS, Wellesley College; JOHN DEWEY, 
 Columbia University ; J. R. ANGELL, University of Chicago; C. LADD FRANKLIN, 
 Baltimore; H. N. GARDINER, Smith College; G. H. HOWISON, University of 
 California ; P. JANET, College de France ; JOSEPH JASTROW, University of Wis- 
 consin; ADOLF MEYER, N. Y. Pathol. Institute ; C. LLOYD MORGAN, University 
 College, Bristol; HUGO MONSTERBERG, Harvard University; E. A. PACE, 
 Catholic University, Washington ; G. T. W. PATRICK, University of Iow^a ; CARL 
 STUMPF, University, Berlin; R, W. WENLEY, University of Michigan. 
 
 v\^> 
 
 THE DIFFERENCE BETWEEN MEN AND WOMEN IN 
 
 THE RECOGNITION OF COLOR AND THE 
 
 PERCEPTION OF SOUND 
 
 BY MABEL LORENA NELSON, 
 
 University of California. 
 
 THE MACMILLAN COMPANY, 
 
 41 NORTH QUEEN ST., LANCASTER, PA. 
 
 66 FIFTH AVENUE, NEW YORK. 
 
 Agent: G. E. STECHERT, London (2 otar Yard, Carey St. W. C); 
 Lbipzig (Hospital St., :o; Paris (76 rue de Renaes). 
 
 P?90^iciog:in3i ^dWMv\, 
 
[Reprinted from The Psychological Rbvikw, Vol. XII., No. 5, Sept., 1905.] 
 
 THE DIFFERENCE BETWEEN MEN AND WOMEN IN 
 
 THE RECOGNITION OF COLOR AND THE 
 
 PERCEPTION OF SOUND. 
 
 BY MABEL LORENA NELSON, 
 University of California. 
 
 (Communicated by Professor Howison.) 
 
 I. The Recognition of Color. 
 
 In testing the sensitivity of the eye to colors, Dr. Nichols 
 found that men where more sensitive to red, ^'■ellow and green, 
 while the women excelled in blue. He mixed a white powder 
 with colored pigments. A series of mixtures, varying from 
 white to clearly colored mixtures, were presented to the sub- 
 jects (31 men and 23 women), who sorted them according to 
 shade and hue. When once the women recognized the color of 
 the compound, they were more accurate in detecting the degree 
 of saturation of the various mixtures ; yet with the exception of 
 blue the women required more parts of the pigment mixed with 
 the white before the tint of the compound was recognized. 
 
 Miss Thompson, on the other hand, finds that women are 
 the more sensitive to colors. She tested 20 men and 20 woman 
 with five colors, and found that the women could recognize 
 squares of colored paper (red, green and blue) at a greater dis- 
 tance than could the men. The squares were pasted on cards, 
 one black and one white. The tests were conducted in a dark 
 room, the cards being illuminated by a Welsbach burner. Her 
 conclusion is that men's eyes are surely less keen in the recog- 
 
 1 Edward L. Nichols, ' On the Sensitiveness of the Eye to Colors of a Low 
 Degree of Saturation,' Am. four, of Science^ Series 3, Vol. 30 (18S5), p. 37. 
 
 271 
 
 Onlwfsltjj of California 
 
 logical Labofafof], 
 
272 MABEL L. NELSON. 
 
 nition of the color of an object. "Yellow is the only color for 
 which the men's record is better than the women's." ^ 
 
 By a different method than either of the two mentioned 
 above, I attempted to discover the difference between men and 
 women in the recognition of color. In the following experi- 
 ments a Glan spectrophotometer was used; the source of light 
 was a Welsbach burner placed .43 meters from the instrument. 
 
 Before beginning my work, August, 1903, I selected five 
 bands of color in the spectrum, which appeared to me to be char- 
 acteristic of red, yellow, green, blue and violet. The wave- 
 lengths of the middle of the five bands were approximately, 
 A, 6575, X5800, X. 5250, X4700 and X4450, respectively. The 
 five bands were spacially equal in width, and measured about 
 one twentieth of the length of the visible spectrum. During 
 the tests all the spectrum was cut off except the band which 
 stood for one of these five colors. The subject then looked into 
 the eye-piece of the spectrophotometer, and was asked to observe 
 and name the color, while the intensity of light was raised from 
 0° to a maximum, by slowly revolving the Nicol prism of the 
 apparatus through an angle of 90°. The figures in tables I., 
 II., and III., represent the readings in this angular scale, and. 
 not the absolute intensity of the light. The intensity of the 
 light at any time varies approximately as the sin^«; a being the 
 reading on the scale. 
 
 Yet even at 0° there is some illumination of the spectrum 
 (due to dispersion of light by the prism), so that at 0° every 
 subject was able to see a band of light, which in general appeared 
 white or gray. A few subjects could confidently recognize the 
 color of the band at 0°. The violet end of the spectrum is of 
 such low intensity that a blue-violet was chosen. The yellow 
 strip selected includes all the yellow in the spectrum with a 
 narrow band of yellow-green on one side, and a narrow band of 
 orange on the other. A strip narrow enough to have included 
 only pure yellow would have been too narrow to be used with 
 the other colors, without being recognized by its lessened width, 
 and, on the other hand, the width of the other colors could not 
 
 • Helen Bradford Thompson, Psychological Norms in Men and Wometi, 
 University of Chicago Press (1903), p- 87. 
 
DIFFERENCES BETWEEN MEN AND WOMEN. 273 
 
 well be reduced without making their area so small as to be 
 recognized with difficulty by untrained observers. 
 
 Three separate hours were given to the experiment by each 
 of the 40 subjects. During the first hour the subject was tested 
 with Holmgren's worsteds for color-blindness. This took from 
 30 to 40 minutes. The room was then darkened, and the 
 remainder of the hour was spent in practice upon observation of 
 strips of the spectrum. The second hour the subject rested his 
 eyes for 20 minutes in the darkened room before looking into 
 the photometer. One determination was then made for each of 
 the 5 colors, but with one eye only. The third hour was a 
 repetition of the second, except that the other eye was used. 
 
 All conditions were kept as uniform as possible ; the pres- 
 sure of the gas was regulated by an automatic machanism and 
 constantly noted ; and the intensity of the color was increased 
 at a constant rate of 1° per second. At the end of every 10 
 seconds, the subject looked away and rested his eye. Ten men 
 and ten women used the right eye first, and an equal number 
 of men and women used the left first. The order in which the 
 colors were presented was varied ; a given order was presented 
 to but one man and one woman. The subjects were not told 
 what colors would be shown them, nor that the same color would 
 be seen for a second time. They were asked to look into the 
 instrument, to report as soon as they saw any color, and to name 
 the color as soon as they could recognize it. 
 
 There is a disadvantage in depending entirely on the name 
 given to the color seen, but this was minimized as far as possible, 
 for any peculiarity in naming the colors was noted when the 
 subjects sorted the Holmgren worsteds ; and when there was any 
 doubt in my mind, or in the mind of the subject, the worsteds were 
 brought out again and correction was made for any peculiarity 
 in nomenclature. At times I could decide on no threshold (as 
 in a case when the subject saw no green at all, but at the maxi- 
 mum intensity called that color yellow). It therefore happens 
 that the average and median are at times calculated on less than 
 20 cases. I did not assume that the threshold for such subjects, 
 as the one just mentioned, was greater than 90, for at 90 the 
 strip was distinctly visible to him, and any increase in intensity 
 
274 
 
 MABEL L. NELSON. 
 
 would only serve to make it more yellow. Even when green 
 was suggested to him, he refused to accept it as a proper name 
 for the color. 
 
 The results of these tests, according to one method of com- 
 putation, appear in Table I. Using the average as the basis of 
 our deductions, it would appear that the right eye of men is 
 better than the right eye of women for all colors but violet ; and 
 
 Table I. 
 
 Threshoi^ds For the; Recognition of C01.0R (in Angles of Nicol's 
 
 Prism). 
 
 Women. 
 
 
 Right Eye. 
 
 Left Eye. 
 
 
 •6 
 
 i 
 
 
 "3 
 
 a 
 
 ID 
 
 3 
 
 2 
 
 "3 
 
 
 1 
 
 d 
 
 V 
 
 3 
 
 5 
 
 ■3 
 
 
 
 > 
 
 
 
 
 > 
 
 
 >- 
 
 
 
 
 > 
 
 Average. . . . 
 
 II.6 
 
 13.8 
 
 II-3 
 
 25.02 
 
 24-3^ 
 
 8.8 
 
 7-9 
 
 8.0 
 
 28.82 
 
 26.4 
 
 M. V. from Av. 
 
 S.4 
 
 9-5 
 
 5.1 
 
 11. 2 
 
 8.0 
 
 3-7 
 
 5.6 
 
 2.5 
 
 15-3 
 
 9-7 
 
 Median . . . 
 
 7-5 
 
 1 0.0 
 
 1 0.0 
 
 20.02 
 
 20.0 
 
 lO.O 
 
 7.0 
 
 8.0 
 
 24.02 
 
 25-5 
 
 Men. 
 
 Average. . . . 
 M. V. from Av. 
 
 Median . . . 
 
 8.9 
 3-6 
 S.o 
 
 6.7 
 8.0^ 
 
 8.0^ 
 
 2.0 
 
 lo.o' 
 
 16.9^ 
 
 7-3 
 
 28.43 
 25.03 
 
 7.6 13.7 
 5-1 8.3 
 6.S 1 0.0 
 
 7-3' 
 2.4 
 7.0' 
 
 17.4' 
 10.8 
 
 26.6« 
 10.4 
 
 /p.o2 
 
 Table II. 
 
 Women. 
 
 
 Right Eye. 
 
 Left Eye. 
 
 
 
 1 
 
 a 
 
 u 
 u 
 
 
 
 43 
 
 3 
 
 B 
 
 (U 
 
 > 
 
 ■d 
 
 1 
 
 "53 
 > 
 
 Green. 
 
 a3 
 
 3 
 
 s 
 
 "o 
 
 > 
 
 Average. . . . 
 
 8.4 
 
 5-8 
 
 9-9 
 
 17-5 
 
 22.4 
 
 7-5 
 
 4.8 
 
 7-2 
 
 18.8 
 
 25-1 
 
 M. V. from Av. 
 
 6.4 
 
 3-7 
 
 3-2 
 
 6.6 
 
 5-9 
 
 2.1 
 
 3.8 
 
 2.9 
 
 9.0 
 
 8.8 
 
 Median . . . 
 
 7.0 
 
 4-5 
 
 lO.O 
 
 18.0 
 
 20.0 
 
 7-5 
 
 4.0 
 
 8.0 
 
 18.0 
 
 25-5 
 
 Men. 
 
 Average.. . . 
 M. V. from Av. 
 Median . . . 
 
 7-7 
 
 8.2 
 
 9.4' 
 
 /5.02 
 
 27.63 
 
 6.3 
 
 7.0 
 
 12.0 
 
 14-3' 
 
 4.6 
 
 34 
 
 3-2 
 
 7.0 
 
 II.O 
 
 4.6 
 
 3-6 
 
 8.5 
 
 2.5 
 
 7.0 
 
 7.5 
 
 9.02 
 
 14.6^ 
 
 23.03 
 
 5-0 
 
 9.0 
 
 7-5 
 
 14.0^ 
 
 23-3' 
 
 6.8 
 
 ^0.53 
 
 1 An italic numeral in tables I., II., and III., indicates that it is less than the 
 corresponding numeral for the other sex. 
 
 2 19 subjects. 
 2 17 subjects. 
 
DIFFERENCES BETWEEN MEN AND WOMEN. 
 
 275 
 
 Table III. 
 Women, 
 
 
 
 ] 
 
 Right Eye. 
 
 
 
 
 I.eft Eye. 
 
 
 
 •6 
 
 i 
 
 
 
 a 
 u 
 
 OJ 
 
 u 
 
 
 
 
 > 
 
 •6 
 
 
 Green. 
 
 6 
 
 3 
 
 s 
 
 
 > 
 
 Average. . . . 
 
 5-1 
 
 .?•«? 
 
 7-0 
 
 12.0 
 
 17.0 
 
 5-9 
 
 .?-^ 
 
 6.4 
 
 14.6 
 
 21. 1 
 
 M. V. from A v. 
 
 4-1 
 
 34 
 
 3-5 
 
 7.2 
 
 «.3 
 
 34 
 
 3-2 
 
 2.8 
 
 8.1 
 
 9.2 
 
 Median . . . 
 
 3-5 
 
 4.0 
 
 7.0 
 
 13.0 
 
 19.0 
 
 5-0 
 
 3-0 
 
 5-0 
 
 14.0 
 
 23.0 
 
 Men. 
 
 Average. . . . 
 M. V. from Av. 
 Median . . . 
 
 6.5 
 5.0 
 6.0 
 
 4.6 
 3-7 
 4.5 
 
 7-5 
 3-7 
 8.0 
 
 10.4 
 3.9 
 
 lO.O 
 
 14-7 
 
 9-1 
 
 17.0 
 
 4-9\ 
 4.8 
 
 2-5 
 
 3-6 
 3-3 
 3.0 
 
 6.8 
 3-3 
 
 7-5 
 
 9-5 
 
 4.8 
 
 lO.O 
 
 13.8 
 
 8.7 
 
 /7-5 
 
 that the left eye of men is better than the left eye of women for 
 red, green and blue; equal for violet, and worse for yellow. 
 The norm would lead to the same conclusion, but if the median 
 is used in place of the average, a somewhat different result is 
 obtained. When we consider the large variation, we are prob- 
 ably not justified in saying more than that women are in general 
 less keen in the recognition of colors. Yellow and violet are 
 the only colors in which they seem to excel, and in these they 
 excel with but one eye. 
 
 Yellow was the color most difficult to name at a low intensity, 
 for the traces of green and orange on the edges of the strip 
 selected confused the subjects. Only a few saw a uniform 
 color. More men than women detected the presence of green 
 and orange. The large threshold of both men and women is 
 probably due to the inability to find an appropriate name for this 
 complex, rather than to a low sensitivity to the color itself. The 
 larger threshold of the men may possibly be due to their greater 
 sensitivity to the green and orange, and consequently their 
 greater confusion. 
 
 The women's failure to name the colors correctly at a low 
 intensity cannot be due to their ignorance of the proper name, 
 since at the maximum intensity they named the colors as accu- 
 rately as did the men. Table IV. gives the different names 
 applied to the colors as they appeared at the maximum intensity, 
 with the number of men and women using each name. The 
 parenthesis indicates that the subjects added those words after 
 
276 
 
 MABEL L. NELSON. 
 
 being pressed for a closer description, and in many cases only- 
 after other colors had been suggested to them. In some cases 
 the subjects gave two and even three names to the strip of color 
 shown them. As the strips were practically uniform, with the 
 one exception of 3'ellow, it is probable that the knowledge that a 
 
 Table IV. 
 
 Names Given to the Standard Colors. 
 
 Red. 
 
 Red 
 
 Red (towards orange) 
 Red (towards purple) 
 
 Orange-red 
 
 Red-orange 
 
 Right Eye. . 
 
 Men. 
 
 14 
 
 4 
 
 12 
 
 4 
 2 
 
 I 
 I 
 
 Left Eye 
 
 17 
 
 I 
 2 
 
 II 
 
 3 
 2 
 
 4 
 
 Yellow. 
 
 Red, yellow and green . 
 Orange-red and yellow 
 Red and orange . . . . 
 
 Orange 
 
 Orange-yellow . . . . 
 Yellow 
 
 Green, 
 
 Green 
 
 Green (towards yellow) . 
 
 Yellow-green 
 
 Yellow and green .... 
 Yellow, green and blue . 
 Orange and yellow-green 
 
 Yellow 
 
 Green- yellow 
 
 8 
 3 
 
 7 
 
 5 
 4 
 6 
 
 3 
 
 6 
 
 10 
 
 I 
 
 2 
 
 
 I 
 
 2 
 
 I 
 
 I 
 
 Blue. 
 
 Blue 
 
 Violet-blue 
 
 Green-blue 
 
 Violet, green and blue 
 
 Blue-green 
 
 Blue-violet 
 
 Blue and violet . . . 
 
 786 
 4 5 
 
 6 3 5 
 
 633 
 I 
 
 III 
 
 Violet. 
 
 Violet 
 
 Violet (towards blue) 
 Violet (towards red) 
 
 Blue-violet 
 
 Violet-blue 
 
 Blue 
 
 Blue (towards green) 
 
 12 
 
 14 
 
 14 
 
 6 
 
 2 
 
 6 
 
 2 
 
 I 
 2 
 
 I 
 
 
DIFFERENCES BETWEEN MEN AND WOMEN. 
 
 377 
 
 spectrum was being used helped to suggest the neighboring 
 colors, though no doubt some subjects did actually discern a 
 difference in the two edges of the band. 
 
 At the close of the tests, 10 men and an equal number of 
 women were shown the whole spectrum, and asked to select the 
 5 portions which they called the best and purest bands of red, 
 yellow, green, blue and violet. The results are given in 
 Table V. The numbers represent the centers of the narrow 
 
 Table V. 
 
 Readings in Case of Free Selection of Colors. 
 
 Women. 
 
 
 Right Eye. 
 
 Left Eye. 
 
 
 
 i- 
 
 
 
 _j 
 
 
 i 
 
 
 
 _J 
 
 
 ■o 
 
 
 
 
 
 
 "O 
 
 
 
 
 
 
 
 
 
 
 s 
 
 "3 
 !> 
 
 11 
 
 "3 
 
 
 
 s 
 
 
 
 > 
 
 Average .... 
 
 8.42 
 
 10.57 
 
 12.99 
 
 15.96 
 
 17-93 
 
 8.53 
 
 10.84 
 
 13.13 
 
 16.18 17.92 
 
 M. V. from Av . 
 
 •17 
 
 .19 
 
 •45 
 
 •27 
 
 .28 
 
 .18 
 
 •31 
 
 .34 
 
 .25 .24 
 
 Median .... 
 
 8.45 
 
 10.48 
 
 12.75 
 
 15.82 
 
 18.01 
 
 8.52 
 
 10.83 
 
 13.25 
 
 16.20 17.92 
 
 Men. 
 
 Average .... 
 
 M. V. from Av . 
 
 Median .... 
 
 Readings actu- 
 ally used for 
 standard colors 
 
 8.47 
 
 .09 
 
 8.48 
 
 8.50 
 
 10.83 
 
 .21 
 
 10.80 
 
 10.50 
 
 12.57 
 
 •43 
 
 12.88 
 
 12.50 
 
 16.13 
 
 .60 
 
 15.94 
 
 16.00 
 
 18.23 
 
 .40 
 
 18.24 
 
 18.00 
 
 '.52 
 .14 
 '.51 
 
 10.74 
 
 .38 
 
 10.75 
 
 12.89 
 
 .41 
 
 12.90 
 
 15.99 
 
 .25 
 
 16.03 
 
 18.34 
 
 .55 
 
 18.30 
 
 band chosen, the visible spectrum running from about 7 to 22 
 — beyond 23 for some of the subjects. The standard colors 
 used in the preceding tests are represented by the numbers 8.5, 
 10.5, 12.5, 16 and 18. The colors selected by the subjects are 
 close to those used in the tests. The wave-lengths are approxi- 
 mately the same except for yellow and green. A 5700 was 
 chosen for yellow by the left eye of women, and by the right 
 eye of men ; and A 5150 was chosen for green by the left eye 
 of women. This is consistent with the fact that so large a num- 
 ber called the standard green a yellow-green (see Table IV.). 
 From the names given to the standard violet we might expect 
 the subjects to choose a violet farther away from the blue. It 
 is true that the men did, yet the difference between 18 and 18.34 
 is not perceptible. In endeavoring to choose the colors on dif- 
 
zyS MABEL L. NELSON. 
 
 ferent days, I find in my own case that the variation from the 
 average is between i per cent, and 1.5 per cent, for red, yellow, 
 green and violet, and a little over 2 per cent, for blue, being 
 but little less than the variation from the average of the 10 
 women. 
 
 Instead of waiting until the subject could name the color 
 with certainty, we might take, as the more probable threshold 
 of recognition, the reading where the color was first correctly 
 named, even though it was named with doubt and reservation, 
 and also the reading where the subjects gave a name so near 
 the standard as to make it probable that they recognized the 
 standard color, but had not secured the most appropriate name. 
 For comparison I have calculated this probable threshold and 
 in so doing I have allowed myself some freedom. I have not 
 taken the lowest reading when my knowledge of the subject 
 and the evidence of later reports made it certain that the first 
 correct report was merely a lucky guess. 
 
 Comparing these results, given in Table II., with those given 
 in Table I., we see that woman's record with the right eye is 
 here lower than man's for yellow as well as for violet ; her 
 record with the left eye is still lower for yellow, and in addition 
 is probably lower for green. These results, differing as they 
 do from those obtained from Table I., may simply mean that 
 the men were more cautious, that they did not venture a name 
 until they were fairly sure it would fit ; while the women would 
 speak as soon as they discovered the region to which the color 
 belonged, afterwards locating it more exactly. 
 
 Going over the original data for a third time, I calculated the 
 thresholds in still another way. The threshold is now taken to 
 be the reading where some closely kindred color or some com- 
 ponent of the color, as it appeared to the subject at the maximum 
 intensity, was named. For example, if at the maximum a color 
 appeared green-blue to a certain subject, then we may assume 
 that at the first mention of either blue or green, the color was 
 really perceived by that subject. Table III. shows the thres- 
 holds calculated in this way. Orange was accepted as a cor- 
 rect answer for either red or yellow ; if the green seemed a 
 yellow-green, then either yellow or green was accepted for 
 
DIFFERENCES BETWEEN MEN AND WOMEN. 279 
 
 green. Ample allowance is thus made for individual dif- 
 ferences of nomenclature ; and we have a threshold of recog- 
 nition of something, which is a close approach to the standard, 
 if it is not the standard itself. Woman's right eye is superior to 
 man's right in this kind of recognition when the standards are 
 red, yellow and green : her left is superior to man's left when 
 the standards are yellow and green. The superiority of men 
 in blue and violet is, on the whole, more marked than is the 
 superiority of women in yellow and green. 
 
 When we compare Tables I., II. and III., we find that in 
 spite of some discrepancies, there is a certain uniformity. In 
 every instance the men have a lower threshold for blue. For 
 the left eye they have a practically equal or lower threshold for 
 violet ; for the right eye a greater for violet, except when blue 
 or violet-blue is accepted as a correct answer. It seems certain 
 that the men could distinguish blue and the blue factor in the 
 violet at a lower intensity than could the women. In the blue 
 of the 3 tables there is at no time more than 4 men who fail to 
 excel the average woman with the left eye ; and never more 
 than 7 men who fail to excel the right eye of the average 
 woman. With the exception of the right eye in Table I., and 
 possibly the left in Table III., women have the lower threshold 
 for yellow ; yet there are always from 6 to 10 women who fail 
 to excel the average man. Women excelled in red when 
 orange was accepted as a correct answer. The instances when 
 they excelled in green are those in which yellow and green- 
 yellow are accepted as correct answers. 
 
 Taking into account all 3 methods of calculating the thres- 
 holds, the general conclusion would be, that men are clearly 
 superior in the recognition of blue ; and women are possibly 
 superior in the recognition of yellow. These results do not 
 agree at all with those of Miss Thompson, who found that men 
 excelled in yellow alone. The difference between my results 
 and those of Miss Thompson may be due to the fact that 14 out 
 of the 25 men she tested fell into the two classes, which she 
 designates as ' color-blind ' and ' poor in color discrimination ' ; 
 while none of her women were ' color-blind,' and only 4 were 
 'poor.'^ No color-blind person is included in my report, 
 
 ^Psychological Norms, page 88. 
 
28o , MABEL L. NELSON. 
 
 although 5 men and 3 women might be called poor in color dis- 
 crimination. Their mistakes consisted in mixing some of the 
 blues and greens, and in failing to detect anything but a pale 
 tint of red in our laboratory sample of Holmgren's purple. In 
 naming the spectrum colors, however, these subjects appear to 
 be as good as the average subject tested. 
 
 Miss Thompson finds that the left eye of woman excels her 
 right in all but 3^ellow. In my tables her left eye seems superior 
 in yellow and green ; yet when the number of individuals are 
 counted up, there are but 11 whose left eye excels the right in 
 yellow, and 14 in green ; for the other three colors there is no 
 difference between the two eyes. Miss Thompson finds man's 
 left eye has a better record in yellow alone. I find that in 
 yellow there are 12 men who have a better right eye, against 6 
 who have a better left ; yellow is the only color in which his 
 right eye excels. In red and green I find no difference, but in 
 blue and violet the left eye excels ; in blue 5 men have a better 
 right eye, 8 a better left ; in violet 9 have a better left, 3 a better 
 right. 
 
 Each of the subjects was asked which eye he preferred to use. 
 Most of them had no preference. Of the 20 women, 5 prefered 
 to use the left eye. Each gave, independently, the same reason ; 
 in looking into the instrument with one eye they alway kept the 
 other closed, and could with less effort keep the right eye closed. 
 One, a left-handed woman, prefered to use her right for the 
 same reason, that is, she found it easier to keep her left eye 
 closed. Only 2 men expressed a preference ; both preferred to 
 use the right, they were in the habit of looking into instruments 
 and were accustomed to using the right eye. In the results of 
 these subjects I can find no consistent advantage of the preferred 
 eye over the other. 
 
 II. The Perception of Sound. 
 The following experiments were undertaken with the object 
 of finding any difference that may exist between men and women 
 with regard to the absolute threshold for hearing. The individ- 
 uals tested, 20 men and 20 women, were all students in the 
 University of California. 
 
DIFFERENCES BETWEEN MEN AND WOMEN. 281 
 
 An electric tuning-fork of 100 double vibrations was used in 
 these tests. The noise which attends the sparking of the elec- 
 tric contact was avoided by connecting up the fork in series 
 with a second fork of 100 vibrations in a distant room ; this 
 second fork interrupted the current in the first and permitted its 
 use with continuous closed contact, and thus a noiseless pure 
 tone was obtained. By means of a galvanometer and resistance 
 the current was kept constant ; and by the constant use of com- 
 mutators any permanent alteration in the magnet of the tuning- 
 fork was prevented. The subject sat in an ordinary research 
 room, behind a screen in which was an aperture large enough 
 to receive the ear. During the tests the subject sat with his 
 head pressed against the screen, his ear within the aperture. 
 The intensity of the sound was altered by varying the distance 
 of the tuning-fork from the screen. 
 
 For each of the subjects, a first rough estimate of the greatest 
 distance at which the sound could be heard was made. Then 
 beginning somewhat within this distance, tests were made at 
 intervals of 2.5 centimeters. At each interval a group of 10 
 tests were made, 5 with the tuning-fork going and 5 with it 
 stopped. The order in which the two kinds of tests were taken 
 was constantly varied. All the series of groups were run from 
 above to below the threshold. The subject was given a warn- 
 ing ; he then placed his ear at the aperture and reported whether 
 he heard, or did not hear the sound. When the subject was 
 doubtful the test was repeated. Between the groups the subject 
 relaxed his position and rested. The greatest distance at which 
 80 per cent, of the answers were correct was recorded as the 
 threshold, though groups of tests were also made beyond this 
 point to make sure that the falling off of correct answers was 
 not accidental nor momentary. The thresholds are recorded 
 in Table I. ; the figures represent the number of centimeters 
 from the screen. The average and also the median of the 
 20 subjects are given. One man's threshold was more than 
 twice as great as that of any other one of the 40 subjects. I 
 have therefore also given the average of 19 men, excluding 
 this one. Among the women there was none that seemed ex- 
 ceptional. 
 
28 2 MABEL L. NELSON. 
 
 Table I. 
 
 Threshold for Hearing in Centimeters. Series I. 
 
 20 Women. 20 Men. 
 
 Right ear. Left ear. Right ear. Left ear. 
 
 Average 44.75 38.00 70.25 53.50 
 
 Median 42-50 35-oo 53.75 4S.75 
 
 19 Men. 
 Average . . . 54.50 4S.50 
 
 Variation from the Average. 
 
 20 Women. 20 Men. 
 
 Right ear. Left ear. Right ear. Left ear. 
 
 9.8 9.1 21.0 12.8 
 
 19 Men. 
 8.7 7.7 
 
 The average women of the 20 could hear 17 per cent, far- 
 ther with the right ear than with the left. The average man of 
 the 20 could hear 31 per cent, farther with the right than with 
 his left. The average man of the 19 could hear 12 per cent, 
 farther with his right than with his left. 
 
 The average man of the 20 could hear 19 per cent, farther 
 with his left ear than the average woman could hear with her 
 right ear. The average man of the 19 could hear 8 per cent, 
 farther with the left ear than the average of the 20 women could 
 hear with her right. 
 
 The results show that both the women and the men could 
 hear farther with the right ear than with the left. The men 
 hear much better than the women. There was but one woman 
 who excelled the average man ; and, on the other hand, only 3 
 men fall below the average women. Eight women fall below 
 the lowest man. The men not only could hear further than the 
 women, but the poorer ear of the men was much keener than 
 the better ear of the women. 
 
 A second set of experiments was then undertaken, this time 
 with a tuning-fork of 500 double vibrations. The same subjects, 
 with the exception of 2 men and 2 women were used in these 
 tests. More precautions against external noises were taken. 
 The subject sat in a silent room, from which all noises were ex- 
 cluded by specially constructed walls and doors. One end of 
 a lead pipe has its termination in this silent room, while the 
 
DIFFERENCES BETWEEN MEN AND WOMEN. 283 
 
 Other end terminates in a research room in another wing of the 
 laboratory. The screen used in the first series of tests was set 
 up in the silent room, 1.675 meters from the end of the lead 
 pipe. The tuning-fork of 500 vibrations was set at varying 
 distances from the other end of the pipe in the distant room 
 where the experimenter was. The appearance of a light in the 
 dark room served to warn the subject, who then, as before, 
 placed his ear at the aperture in the screen. Here and in the 
 earlier series of experiments, half of the men and half of the 
 women used the right ear first, the other half used the left first. 
 The subject communicated his answers by means of a telegraphic 
 key. After a first rough estimate of the threshold was made, 
 10 tests were made at regular intervals of i centimeter. The 
 method used was the same as the first group of tests. The fig- 
 ures in Table II. are in centimeters, and represent the distance 
 of the tuning-fork from the end of the tube. 
 
 Table II. 
 Thr:eshoi<d for Hearing in Centimeters. Series II. 
 18 Women, 18 Men. 
 
 Right Ear. Left Ear. Right Ear. Left Ear. 
 
 Average 6.88 5.66 8.61 7.77 
 
 Median 7.00 5.50 8.50 6.00 
 
 Variation from the Average. 
 20 Women. 20 Men. 
 
 Right Ear. Left Ear. Right Ear. Left Ear. 
 
 3.50 3.16 5.00 4.80 
 
 The average woman could hear 21 per cent, farther with 
 her right ear than with her left ear. The average man could 
 hear 10 per cent, farther with his right than with his left ear. 
 
 The average man could hear 1 1 per cent, farther with his 
 left ear than the average woman could hear with her right ear. 
 
 The results are as before : the men hear farther than the 
 women ; the right ear of both men and women is keener than 
 the left. The changed conditions and the difference in the note 
 has not changed the general result, though it affected the rela- 
 tive positions of individuals within the groups of subjects. The 
 two men, whose records were the highest in the tests with the 
 tuning-fork of 100 vibrations, fell below the average of the men 
 
284 MABEL L. NELSON. 
 
 when the fork of 500 vibrations was used. The two women 
 who stood highest in the first series of tests also stood highest 
 in the second series ; but in general it is not true that the women 
 who heard farthest in the first series, also heard farthest in 
 the second series. Fully 50 per cent, of the men whose records 
 were higher than the median in the first series, fell below the 
 median in the second series ; the same is true of the women, 
 although the women do not make such a decided change. 
 They change from a short distance on one side of the median 
 to a short distance on the other. The superiority of the men is 
 not so marked. With the left ear, 7 women excel the average 
 man; with the right ear, 4 women excel the average man. 
 Eight men fall below the average woman with both the right 
 and left ear. 
 
 The superiority of the right ear over the left is as marked in 
 this second series as it was in the first. Not only was the right 
 ear of the average man and average woman better than the left, 
 but the right ear of almost every individual subject was either 
 better than, or equal to, the left (see Table III.). Of the 40 
 
 Series i. 
 
 Number of women with a better right ear 16 
 
 Number of men with a better right ear 14 
 
 Number of women with a better left ear i 
 
 Number of men with a better left ear 2 
 
 Number of women with the right and left ear equal 3 
 
 Number of men with the right and left ear equal 4 
 
 Series ii. 
 
 Number of women with a better right ear 12 
 
 Number of men with a better right ear 14 
 
 Number of women with a better left ear 3 
 
 Number of men with a better left ear 3 
 
 Number of women with the right and left ear equal 3 
 
 Number of men with the right and left ear equal i 
 
 subjects, but one man was found whose left ear was better than 
 his right in both series. Of the remaining 5 subjects whose left 
 proved better than the right in second series, the right and left 
 of two had been equal, the right of 3 had been slightly better 
 than the left in the first series. 
 
 None of the 40 subjects knew of any defect in their hearing. 
 They were asked if they knew of any difference between the 
 
DIFFERENCES BETWEEN MEN AND WOMEN. 2S5 
 
 right and the left ear. Seven (2 woman and 5 men) thought 
 the right was better ; 5 (3 women and 2 men) thought the left 
 better. None of these gave, or pretended to give, any good 
 reason for their opinion ; and in every case their opinion, when 
 they thought better of the left, was not in accord with the results 
 of the tests. The one man whose left ear proved to be better, 
 knew of no difference. 
 
 The results indicating more acute hearing in the men can- 
 not be due to a greater recklessness in answering. If this were 
 true, we would expect the men to make more errors than the 
 women when the fork was silent. On the whole they made 
 fewer such errors. Many subjects made no errors of this kind. 
 In the first series, 9 men made a total number of 46 errors, 20 
 with the left ear and 26 with the right ; 9 women made 42 
 errors, 9 with the left and 33 with the right. In the second 
 series the men were more cautious; 6 men made a total of 21 
 errors, 9 with the right, 12 with the left; 13 women made 68 
 errors, 29 with the right, and 39 with the left. 
 
 Many in this second series did not use the signal ' doubtful ' 
 at all. The number of such answers is given in Table IV. In 
 this second series the left ear of both men and women was not 
 only less acute, but more doubt was expressed and more errors 
 made when it was used ; the variation from the average is also 
 slightly greater. 
 
 Table IV. 
 
 Series II. 
 Right ear, fork sounding. 
 45 ' doubtful ' answers were made by 14 women. 
 95 " " " " " 16 men. 
 
 Right ear, fork silent. 
 6 ' doubtful ' answers were made by 4 women. 
 2 " " " " " 2 men. 
 
 Left ear, fork sounding. 
 53 ' doubtful ' answers were made by 13 women. 
 116 " " " " " 16 men. 
 
 Left ear, fork silent. 
 No ' doubtful ' answers made. 
 
 Fechner ^ found the left ear to be better than the right. His 
 
 ' In Poggendorfs Aiinalen der Physik und chemie, vierte Reihe, Band iii. 
 S. 500. 
 
386 MABEL L. NELSON. 
 
 method was to place a watch directly before the subject, who 
 after closing with the forefinger first one ear then the other, 
 stated in which ear the watch seemed louder. Such a method 
 records only the subject's opinion. I found that results obtained 
 by a test similar to Fechner's were not in accord with the results 
 obtained by the tests with the tuning-fork. The subjects were 
 the same i8 men and i8 women used in the second series of 
 tests with the tuning-fork. A watch was held in front of the 
 subject, who, after turning the head slowly from side to side, 
 stated in which ear the watch seemed louder. Eight (4 men 
 and 4 women) said the watch seemed louder in the left ear. 
 The former tests seemed to show that the left ear of but one man 
 was better ; the right ear of the remaining 7 had been shown to 
 be better. Five (i man and 4 women) said the watch seemed 
 louder in the right ; the remainder of the subjects could tell of 
 no difference. Again, I brought the watch from a point beyond 
 to a point within the range of hearing, and asked the subjects 
 with which ear they first heard the sound. The 8 subjects 
 mentioned in the first test with the watch, answered that they 
 heard it first with the left ear; and the same 5, who before 
 seemed to hear it louder with the right, now said they heard it 
 first with the right ; the remainder of the subjects could tell no 
 difference. There thus seems to be a slight tendency to think 
 better of the left ear, even when that ear is the poorer. It is of 
 course possible that if a tuning-fork had been used instead of a 
 watch a different result would have been obtained.^ 
 
 2The MS. of this article was received March. 11, 1905. — Ed. 
 
 Onlwrsltj of California 
 
 Psyottoiogjcal laboratonf. 
 
REPRINTED FROM 
 
 VOL XII. No. 5. September, 1905. 
 
 THE 
 
 Psychological Review 
 
 EDITED BY 
 J. MARK BALDWIN HOWARD C. WARREN 
 
 Johns Hopkins University ^^^ Princeton University 
 
 CHARLES H. JUDD, Yale University [Editor of the Monograph Series). 
 
 WITH THE CO-OPERATION FOR THIS SECTION OF 
 
 A. C. ARMSTRONG, Wesleyan University ; ALFRED BINET, Ecole des Hautes- 
 feTUDES, Paris; W. L. BRYAN, Indiana University; WILLIAM CALDWELL, Mc- 
 GiLL University; MARY W. CALKINS, Wellesley College; JOHN DEWEY, 
 Columbia University ; J. R. ANGELL, University of Chicago ; C. LADD FRANKLIN, 
 Baltimore; H. N. GARDINER, Smith College; G. H. HOWISON, University of 
 California ; P. JANET, College de France ; JOSEPH JASTROW, University of Wis- 
 consin; ADOLF MEYER, N. Y. Pathol. Institute; C. LLOYD MORGAN, University 
 College, Bristol; HUGO MONSTERBERG, Harvard University; E. A. PACE, 
 Catholic University, Washington; G. T. W. PATRICK, University of Iowa; CARL 
 STUMPF, University, Berlin; R. W. WENLEY, University of Michigan. 
 
 ^V% 
 
 EXTENSITY AND PITCH 
 
 BY DR. KNIGHT DUNLAP, 
 University of California. 
 
 THE MACMILLAN COMPANY, 
 
 41 NORTH QUEEN ST., LANCASTER, PA. 
 
 66 FIFTH AVENUE, NEW YORK. 
 
 Agent: G. E. STECHERT, London (2 Gtar Yard, Carey St. W. C); 
 
 Leipzig (Hospital St„ 10; Paris (76 rue de Renaes). 
 
 Psyatioiogieai bl3nfS(;^n 
 
[Reprinted from The Psychological Review, Vol. XII., No. 5, Sept., 1905.] 
 
 EXTENSITY AND PITCH. 
 
 BY DR. KNIGHT DUNLAP, 
 University of California. 
 
 Psychologists in general agree that ' sensation ' has the four 
 characters of quality, intensity, duration (or protensity), and 
 feeling-tone. To these some would add volume (or extensity), 
 and others would add vividness. There seems to be no reason 
 why the list should not be somewhat further extended by add- 
 ing local significance, which may with advantage be distin- 
 guished from quality ; and meaning, or symbolic value, which 
 is at least as important as an}^ of the other characters. Even 
 with these additions there is question whether the list is com- 
 plete, but it is sufficiently so for present purposes. 
 
 These characters of simple sense objects are not parallel in 
 their functions, but differ in their relation to the existence of 
 these sense objects, and in their modes of variation. The first 
 three which we have named seem to be essential ; we can not 
 conceive of the existence of a ' sensation 'which has no duration, 
 or which has no intensity, or which has no quality; i. e., which 
 is no particular kind of 'sensation.' Whether the same holds 
 true for extensity is perhaps less certain, but there is strong 
 evidence that way, as we shall see later. Vividness, feeling 
 tone, local significance, and meaning, seem to be less essential. 
 There conceivably may be sense objects present to conscious- 
 ness which yet are of zero vividness ; that is, they are either in 
 the realm of so-called subconsciousness, or else they are ne- 
 glected in their immediate nature, and their meaning alone taken 
 into account. Local significance, again, may possibly be lack- 
 ing ; olfactory objects, in particular, never seem to have in 
 themselves any local signs, although of course they are local- 
 ized by the help of tactual and muscular experiences ; some- 
 thing of the same kind seems to be true of auditory sensations 
 also. It may be that local signs exist only in touch and sight ; 
 
 287 
 
 ilDlYSfsitji of Galiforola 
 
 PsyeliQiogioal Laboratofy. 
 
2S8 DR. KNIGHl DUN LAP. 
 
 or on the other hand it may be that there is a system of local 
 signs present in hearing which is represented by the system of 
 pitches ; but at least we can conceive of ' sensations ' which 
 should be entirely devoid of this character. Suppose, for in- 
 stance, two nerve endings which should when stimulated produce 
 sensual processes corresponding to the same sensuous quality ; 
 there might be in these processes nothing which would enable 
 us to distinguish one from the other, and yet both would be real. 
 
 Sense objects may be neutral in feeling-tone, which is 
 equivalent to their having no feeling tone. Some psychologists 
 insist on calling neutrality a definite feeling-tone, thereby mak- 
 ing feeling-tone an essential character ; but this seems an un- 
 called for complication, since feeling-tone signifies the character 
 by which states of consciousness differ as regards pleasantness 
 (or unpleasantness, whichever you chose) and when this factor 
 is reduced to zero there is no better excuse for saying that it 
 still exists than there is for saying that zero intensity and zero 
 duration are still existent intensity and duration. 
 
 Meaning, likewise, is not necessarily present. A sense ob- 
 ject may conceivably be taken for just what it is, without refer- 
 ence to anything else. Of course, the more experience we 
 have, the more nearly impossible this becomes ; but even so we 
 may hold that the absence of meaning does not imply the non- 
 existence of * sensation.' 
 
 These various characters of simple sense objects show also 
 diverse types of behavior in the analysis of psychical com- 
 pounds. The mere quality of a compound involves nothing 
 which is not in the qualities of its components. So the intensity 
 and duration are direct functions of the intensities and durations 
 of its elements. Or, if the more accurate form of statement is 
 preferred, we may say that the qualities, intensities, and dura- 
 tions, of the elements into which the complex state is analyzed 
 will include all qualities, intensities, and durations found in the 
 complex, and no other ; there is neither surplusage nor deficit 
 resulting from the analysis. The complex as a whole has no 
 quality which cannot be reduced to the qualities of the elements ; 
 no intensity which cannot be reduced to a summation of ele- 
 mentary intensities ; and no duration which is different from the 
 duration of a definite number of its elements. 
 
EXTENSITY AND PITCH. 289 
 
 Extensity falls in with duration. But in both these charac- 
 ters we must be prepared for an apparent surplusage resulting 
 from analysis, which apparent surplusage is due to the phenom- 
 ena of superposition; /. d*., simultaneity in time or collocation 
 in space. When we take these factors into account the appa- 
 rent post-analytical redundancy disappears. 
 
 With regard to the other characters of elementary sense ob- 
 jects, this simple analytic relation does not hold. There are 
 factors in the feeling-tone of a complex that are not assignable 
 to any of the sensuous elements into which the complex maybe 
 resolved, but which seem to belong to the complex as such, or 
 perhaps to intellectual elements. The meaning of a complex 
 is far different from the total meanings of its elements. Vivid- 
 ness is scarce amenable to analysis at all, for to a certain extent 
 the vividness of the complex as a whole is inversely proportional 
 to the vividness of its elements. Local significance may be- 
 come entirely lost in a complex, especially when the complex 
 involves the cooperation of two or more senses, and it appears 
 in these cases only by the analysis of the complex into its 
 elements. 
 
 With regard to their analytic behaviour therefore, as well as 
 their essentiality, the feeling-tone, meaning, vividness, and 
 local significance characters differ radically from quality, inten- 
 sity, duration, and extensity. 
 
 There is however one way in which quality differs funda- 
 mentally from intensity, duration, and extensity, and that is in 
 its method of variation. The variations in these last three are 
 continuous from zero to the highest possible value, without any 
 points of special value, /. e., determining points, in the contin- 
 uum ; while the variations of quality pass through definite 
 special or determining points with transition regions between. 
 This difference is formulated in another way in the statement 
 that variation in quality is variation in kind, while variations in 
 intensity, duration, and extensity are not in themselves varia- 
 tions in kind. 
 
 As regards the physiological concomitants of at least five of 
 these characters of simple sense objects, we can speak with 
 confidence. Quality is essentially correlated with the kind 
 
290 DR. KNIGHT DUNLAP. 
 
 of end organ stimulated (or perhaps with the kind of process 
 which is aroused in the end organ and brain cell). Intensity is 
 correlated with the intensity of the process aroused. Duration 
 is identical with the duration of the process, presumably in the 
 central cell. Local significance is the correlate of the particular 
 end organs stimulated ; we may suppose each end organ to have 
 its particular local sign. Extensity has in this respect its full 
 title proven, since it is obviously the correspondent of the num- 
 ber of contiguous end organs stimulated. 
 
 The physiological conditions of the other characters — feel- 
 ing-tone, meaning and vividness — are much more complex, 
 and hence, though we assume that they are - perfectly definite, 
 are not readily assignable. 
 
 This scheme, of four essential characters, and four which 
 may be called accidental.^ is satisfactory until we come to the 
 consideration of sound sensations, at which point it seems at 
 first unsatisfactory. Have we any character with which ^itch 
 can be identified? Duration, intensitjs vividness, feeling-tone 
 and meaning are of course excluded from the possibility, since 
 they all apply to sounds over and above pitch ; so quality, ex- 
 tensity and local significance are left to be considered. Quality, 
 however, is soon put out of the running, since we have shown 
 that in the other senses it varies through various determining 
 points which are few in number for each sense ; whereas pitch 
 varies in a continuum without internal orientation, exactly as do 
 intensity, duration, extensity and vividness. Local significance 
 is the character which we should urge in this connection, if 
 we held to the Helmholtz theory of audition, but since the 
 present disposition is to look upon that theory as mechan- 
 ically untenable, we should be obliged to look for further 
 reasons for our choice, and such reasons, apart from the neces- 
 sity of finding some character with which the identification may 
 possibly be made, are not forthcoming. On the contrary, it 
 seems impossible that pitch can rest upon local signs, since local 
 signs do not in general vary between two extremes, but rather 
 include a manifold of differences which do not admit of easy 
 schematization. The same fact is expressed when we say that 
 intensity, duration, extensity, and likewise pitch, admit of quan- 
 titative comparison, while local signs do not. 
 
EXTENSITY AND PITCH. 29 1 
 
 Extensity, however, furnishes conditions which correspond 
 in every particular to the properties of pitch. It varies con- 
 tinuously between extremes, admits of quantitative estimation 
 more or less exactly, and moreover is directly connected with 
 pitch in introspective analysis. The so-called ' high' notes are 
 sinall. The ' low ' notes are large or voluminous. Differences 
 in pitch, in other words, are directly comparable to differences 
 in planar or linear extent, and the physiological condition of 
 difference in pitch accordingly is probably difference in number 
 of nerve-endings stimulated.^ 
 
 This theory of pitch is much more in accordance with the 
 known facts of tone perception than is the Helmholtz theory. 
 Let us consider first the discrimination of overtones. Accord- 
 ing to the local sign theory there ought to be very little difficulty 
 in recognizing the octave when sounded with the fundamental, 
 for the two components are dependent on the stimulation of two 
 nerve endings or groups of nerve endings which must be rela- 
 tively a considerable distance apart in the series and hence as 
 easily discriminable as two points of light on the retina. On the 
 extensity theory, however, the nerve endings which the higher 
 note stimulates are all stimulated by the lower note ; that is, the 
 higher note is contained in the lower note both psychologically 
 and physiologically, just as if a short streak of light were su- 
 perposed on a long one ; so that the discrimination where the 
 notes harmonize {i. e., where there are no beats), and where the 
 lower (or larger) note is not much less intense than the higher 
 (or smaller), should be rather difficult, which is actually the 
 case. 
 
 Moreover, if differences in pitch depended on differences in 
 
 individual nerve endings stimulated, there would be no reason 
 
 for expecting the lower note in a complex to dominate, t. e.^ to 
 
 give its pitch to the complex. But if the difference in pitch is 
 
 really a difference in volume, we might well expect the larger 
 
 to determine the size of the total complex, as really is the case 
 
 when the lower note is not too weak. 
 
 1 Subsequent to the construction of this theory on purely psychological 
 grounds, I found that Ter Kuile had constructed a physiological theory with 
 which it practically agrees. See Pfliiger's Archiv, 1900, Vol. 79, pp. 146-157 
 and 484-509. 
 
292 DR. KNIGHT DUN LAP. 
 
 In the third place, as regards a changing pitch, we have on 
 either theory something analogous to a perception of motion ; 
 but on the local sign theory the analogous motion would be that 
 of a point generating a line in the field of vision or of touch ; 
 while on the extensity theory the proper analogy would be aline 
 increasing or decreasing in length ; /. e., there is a certain part 
 of the object which remains unchanged by the variation. This 
 is a point on which introspection may differ in different cases, 
 and on which it is hardly trustworthy on account of the sophis- 
 tication of our auditory sense ; in my own observation, however, 
 the shrinking or expanding in linear extension in the field of 
 vision or touch is a perfect analogue of the shifting pitch, and 
 the moving point is not at all applicable. 
 
 Finally, the peculiarities of the complex sound we call ' noise , 
 fit in perfectly with the proposed theory. The analytic char- 
 acteristics of a ' noise ' are : (i) excessive complexity, which is 
 the essential feature, and may be the only one except for the 
 beats to which it gives rise ; (2) progressive variation in the in- 
 tensity and pitch of the components, which is an accidental 
 feature, but which adds greatly to the ' noisiness ' ; and (3) in- 
 definiteness in pitch of the complex determined by the first two 
 characteristics. 
 
 The reason for this indefinitness of pitch becomes clear as 
 soon as we consider the analogy to light sensations. Suppose 
 we superpose many streaks of light of various lengths, making 
 one end of each streak coincident with the corresponding ends 
 of all the others. The result will be a streak of light relatively 
 very intense at one end and fading off at the other, so that the 
 length of the total illuminated area is indefinite. This is just 
 what happens in the case of a noise ; the superposition of the 
 variety of tones makes the exact limits of the complex difficult of 
 determination, although there is a general ^lich. distinguishable. 
 
 The designation of pitch as the form which extensity takes 
 in auditory sensation seems to be the most satisfactory clearing 
 up of the field of sensation characters. Not onl}'^ does it dis- 
 pose of the vexed question of pitch, but it also helps to confirm 
 the right of extensity to be considered an essential character of 
 sensation, instead of an accidental character. 
 
 * The MS. of this article was received February 2, '05. — Ed. 
 
 llnlvefsitj of Umm 
 
 Psycbological Laborstor). 
 
[Reprinted from the Psychological Review. Vol. XVII., No. 4, Julj, 1910.] 
 
 FROM THE UNIVERSITY OF CALIFORNIA 
 PSYCHOLOGICAL LABORATORY. 
 
 XL Experiments on the Reproduction of Distance as 
 Influenced by Suggestions of Ability and Inability. 
 
 BY GRACE MILDRED JONES, M.h- 
 
 Up to the present time the several experiments to determine 
 the effect of suggestion have been made with some important 
 differences in the method of investigation. In the earlier experi- 
 ments the observer was given no instructions to resist any in- 
 fluence by suggestion ; as, for example, in Small's ^ test, where 
 a visual illusion was employed and the children given no warning 
 of such ; so in Binet's^ experiment where the subjects were mis- 
 informed as to the true length of the lines in their relation to 
 one another. The experiments of Pearce,^ and of Smith and 
 Sowton * were made under practically these same conditions. 
 
 With Brand ^ a radically new method was adopted. The 
 subjects were aware of the purpose of the experiment and while 
 the content of the suggestion was to be given place in the mind 
 the observers were warned against any voluntary response to it. 
 Furthermore, the reactions depended not alone upon visual 
 perception but primarily upon the power to reproduce. Bell's ^ 
 experiment in these essential conditions was identical with 
 Brand's. It differed chiefly in this : that a visual type of sug- 
 gestion was used in addition to the vocal. 
 
 In the present investigation, the method in general remained 
 
 ^ Small, 'The Suggestibility of Children,' Pedagog. Sent., 1896, IV., pp. 
 176-220. 
 
 * Binet, La suggestibilite, Annee Psych. V., pp. 82-152. 
 
 ^ H. J. Pearce, 'Normal Motor Suggestibility,' Psych. Rev., 1902, IX., pp. 
 329-356. 
 
 * W. J. Smith and S. C. M. Sowton, 'Observations on Spatial Contrast and 
 Confluence in Visual Perception,' Brit. J. Psych. ^ '^'^'^li H-) PP- 196-219. 
 
 ^J. E. Brand, 'The Effect of Verbal Suggestion on the Estimation of Linear 
 Magnitudes,' Psych. Rev., 1905, XII., pp. 41-49. 
 
 ^ J. C. Bell, 'The Effect of Suggestion upon the Reproduction of Triangles 
 and Point Distances,' American Journal of Psychology, 1908, XIX., pp. 504-518. 
 
 369 
 
 llnlverslty of California 
 
270 GRACE MILDRED JONES. 
 
 the same as with Brand. The nature of the suggestions was 
 changed and instead of being given in the form of a command 
 they conveyed ideas of ability and inability. The chief differ- 
 ence lay in the fact that three types of suggestion were used, 
 the vocal, the visual, and the 'auto,'^ and that a special investi- 
 gation was made of the relative effect of these various types. 
 
 Method of Experiment. 
 
 The apparatus employed in the present experiment was 
 almost identical with that used by Brand. At a distance of 80 
 centimeters from the subject two white pegs were set up show- 
 ing through a narrow slit in a black screen ; below this slit was 
 another, somewhat wider, in which were exposed the visual 
 suggestions. It was so arranged that the slits might be covered 
 and uncovered conveniently to meet the needs of the experi- 
 ment. At a distance of 40 centimeters from the observer was 
 another black screen low enough so that the subject was able to 
 see the horizontal slits in the farther screen where the pegs 
 fixing the standard distance were exposed. On the nearer 
 screen was a ledge where the subject was to adjust correspond- 
 ing pegs in making his ' reproduction.' Both screens were 
 built upon a table at a convenient level ; the background was 
 black and the room but dimly lighted. The pegs themselves 
 were made clearly visible by screened lights. 
 
 The observer responded to six varieties of suggestion and 
 to one signal where no suggestion was offered. Three types of 
 suggestion were used — the visual, made by means of the printed 
 mottoes "You are now able" and "You are now unable"; 
 the vocal, made by the experimenter to the observer in the same 
 words ; and the ' auto,' made by the subject to himself in the 
 words, " I am now able " ; "I am now unable." The sugges- 
 tions were given in irregular order ; after each an interval of a 
 second and a half was allowed before the exposure of the pegs, 
 to give the subject time to concentrate his attention on the idea. 
 The pegs were then exposed for a second and a half, the slide 
 was replaced so as to conceal them, and the observer immediately 
 
 ^ ' Auto ' is the name given to the type in which the observer responded to 
 his own suggestion of ability or inability. 
 
THE REPRODUCTION OF DISTANCE. 27 1 
 
 placed his pegs upon the ledge and adjusted them in accordance 
 with his estimate of the distance between the exposed pegs. 
 This distance, or space interval, was kept constant throughout 
 the experiment ; but of this the subjects were unaware, as their 
 assertions prove. Each of the subjects took it for granted, 
 when the absolute position of the pegs was changed, which 
 occurred after every sixth judgment, that the space interval 
 was changed also. 
 
 The experiment covered a period of five months, from 
 October, 1908, to March, 1909; during this time the subjects 
 were experimented upon at regular intervals and were required 
 to give approximately the same number of judgments at each 
 sitting. Three observers, experienced in psychological methods, 
 were engaged. Five hundred twenty-five estimates were made 
 by each of the three subjects ; that is, seventy-five estimates 
 for each variety of suggestion and seventy-five with no sugges- 
 tion. The subject was instructed to allow each suggestion a 
 place in his mind, to hold the idea it offered, but not to allow 
 it consciously or intentionally to affect his estimate. Toward 
 the close of the experiment each observer reported that he felt 
 certain he was not being influenced in the least degree by any 
 of the types of suggestion. According to their statements no 
 feelings of ability or inability were aroused within them, nor 
 was the experimenter able to observe any outward effect, such 
 as hesitation or the like. 
 
 Results. 
 In that portion of Table I. which presents the averages for 
 the combined seventy-five estimates the results are seen to be 
 uniform for all the three subjects in these respects, that in all 
 twenty-four ' groups'^ where the affirmative of any type is com- 
 pared with the negative of the same type, both the constant 
 
 ' 'Group' is used here and throughout the account to mean a pair of averages, 
 namely the affirmative and negative of any single type of suggestion or of the 
 combined types — and this, either as regards average reproduction (or the con- 
 stant error) or variability. For example, in Table I., in the first series of 
 twenty-five judgments, 30.88 and 30.34 constitute a 'group' for subject X; 1.52 
 and 1.58 another group for the same subject. Thus for each series of twenty- 
 five judgments there are eight groups for each subject, making twenty-four for 
 the three subjects for that series. 
 
272 
 
 GRACE MILDRED JONES. 
 
 error ^ and the variability ^ are appreciably less with the affirma- 
 tive suggestions than with the corresponding negative sugges- 
 tions. And again, in the averages obtained from judgments 
 made with no suggestion there is always less constant error and 
 usually less variability than in any of the averages of estimates 
 with suggestion. 
 
 Table I. 
 The Average Reproduction of the Standard Distance (30 cm. ) 
 
 TOGETHER WITH THE VARIABII^ITY. 
 (The latter given in each case immediately below the average reproduction.) 
 
 
 Averages for First 
 
 Averages lor Second 
 
 Averages for Third 
 
 Averages for Com- 
 
 
 25 Judgments. 
 
 25 Judgments. 
 
 25 Judgments. 
 
 bined 75 Judgments. 
 
 Type of Suggestion. 
 
 Subject 
 
 Subject 
 
 Subject 
 
 Subject 
 
 
 X. 
 30.88 
 
 Y. 
 
 Z. 
 
 X. 
 
 Y. 
 
 z. 
 
 X. 
 
 Y. 
 
 z. 
 
 X. 
 
 Y. 
 
 Z. 
 
 Visual — affirma- 
 
 30-4 
 
 33-64 
 
 28.66 
 
 30-50 
 
 30.38 
 
 27.12 
 
 30.70 
 
 30.86 
 
 28.886 
 
 30.533 
 
 31.626 
 
 tive 
 
 1-52 
 
 1.64 
 
 3-68 
 
 1.74 
 
 .86 
 
 1.04 
 
 2.88 
 
 -94 
 
 1.42 
 
 2.046 
 
 1. 146 
 
 2.046 
 
 Visual — negative 
 
 30-34 
 
 30.08 
 
 33-56 
 
 28.30 
 
 31-04 
 
 30.48 
 
 26.82 
 
 30.S4 
 
 31.08 
 
 28.486 
 
 30.653l3i.706 
 
 
 1.58 
 
 2.04 
 
 3-72 
 
 1-9 
 
 1.48 
 
 1.36 
 
 3-18 
 
 1.08 
 
 1.56 
 
 2.22 
 
 1-533 
 
 2.213 
 
 Vocal — affirma- 
 
 30-94 
 
 30.06 
 
 33-18 
 
 29.16 
 
 30.64 
 
 30.06 
 
 27-75 
 
 30.68 
 
 31.06 
 
 29.28 
 
 30.46 
 
 31-433 
 
 tive 
 
 1-34 
 
 1.34 
 
 3-3 
 
 1.36 
 
 1. 12 
 
 1. 10 
 
 2.32 
 
 1.08 
 
 1-54 
 
 1.673 
 
 1. 18 
 
 1.98 
 
 Vocal — negative 
 
 31.10 
 
 30.58 
 
 33-40 
 
 28.382 
 
 30-90 
 
 30.50 
 
 23.74 
 
 31.02 
 
 31.46 
 
 27-78 
 
 30.83331.786 
 
 
 1-9 
 
 1.66 
 
 3-64 
 
 1-7 
 
 I.I 
 
 1.54 
 
 2.26 
 
 1.38 
 
 1.62 
 
 1-953 
 
 1.38 2.266 
 
 Auto. — affirmative 
 
 30.72 
 
 30.06 
 
 32.96 
 
 28.46 
 
 30.48 
 
 30.16 
 
 27.74 
 
 30.88 
 
 31-76 
 
 28.973 
 
 30.47331.626 
 
 
 1.76 
 
 1.02 
 
 3.28 
 
 1.66 
 
 .84 
 
 .88 
 
 2.3 
 
 1. 12 
 
 1.76 
 
 1.906 
 
 -993! 1-973 
 
 Auto. — negative 
 
 30.88 
 
 30.28 
 
 32.8S 
 
 28.54 
 
 30.50 
 
 30.70 
 
 27.40 
 
 30.74 
 
 31.48 
 
 28.94 
 
 30.50631.686 
 
 
 1.6 
 
 1.6 
 
 3.12 
 
 1.62 
 
 1.54 
 
 1.50 
 
 2.6 
 
 1. 14 
 
 1.96 
 
 1-94 
 
 1.426^ 2.193 
 
 No suggestion 
 
 31.24 
 
 29.76 
 
 32.66 
 
 29.32 
 
 30.52 
 
 30.24 
 
 28.16 
 
 30.72 
 
 31.28 
 
 29-573 
 
 30-333; 3 1. 393 
 
 
 1.72 
 
 1.72 
 
 2.74 
 
 1.24 
 
 .92 
 
 1.64 
 
 2.04 
 
 1.0 
 
 1.52 
 
 1.666 
 
 1. 213 1.966 
 
 ^All types of sug- 
 
 30.81 
 
 30.243 
 
 33-27 
 
 28.583 
 
 30.676 
 
 30.38 
 
 26.761 
 
 30.81 
 
 31-283 
 
 28.724 
 
 30.57631.643 
 
 gestion combined 
 
 1.616 
 
 1-55 
 
 3-456 
 
 1.663 
 
 1. 156 
 
 1.236 
 
 2.59 
 
 1.123 
 
 1.643 
 
 1-956 
 
 1.276 
 
 2. 112 
 
 Affirmative sug- 
 
 30.846 
 
 30.173 
 
 33-26 
 
 28.76 
 
 30.533 
 
 30.20 
 
 27.54 
 
 30.753 
 
 31.226 
 
 29.048 
 
 30.488 
 
 31-561 
 
 gestions combined 
 
 1.54 
 
 1-333 
 
 3-42 
 
 1-56 
 
 -94 
 
 I.O 
 
 ^•5„ 
 
 1.046 
 
 T.57 
 
 1-875 
 
 1. 106 
 
 2.0 
 
 Negative sugges- 
 
 30.773 
 
 30.313 
 
 33-28 
 
 28.406 
 
 30.813 
 
 30.56 
 
 25.98 
 
 30.866 
 
 31-34 
 
 28.388 
 
 30.664 
 
 31.726 
 
 tions combined 
 
 1.693 
 
 1.766 
 
 3-49 
 
 1-74 
 
 1-373 
 
 1.46 
 
 2.68 
 
 1.2 
 
 1.71 
 
 2.037 
 
 1.446 
 
 2.224 
 
 Visual suggestions 
 
 30.61 
 
 30.24 
 
 33-60 
 
 28.48 
 
 30-77 
 
 30.43 
 
 26.96 
 
 30.77 
 
 30.97 
 
 28.686 
 
 30.593 
 
 31-66 
 
 combined 
 
 1-55 
 
 1.84 
 
 3-70 
 
 1.82 
 
 1.17 
 
 1.2 
 
 3-03 
 
 I.OI 
 
 1.49 
 
 2.133 
 
 1.34 
 
 2.13 
 
 Vocal suggestions 
 
 31.02 
 
 30.32 
 
 33-29 
 
 28.77 
 
 30-77 
 
 30.28 
 
 25-75 
 
 30.85 
 
 31-26 
 
 28.513 
 
 30.646 
 
 31.61 
 
 combined 
 
 1.62 
 
 1.5 
 
 3-47 
 
 1-53 
 
 I. II 
 
 1.32 
 
 2.29 
 
 1.23 
 
 1.58 
 
 1.813 
 
 1.28 
 
 2.12 
 
 Auto, suggestions 
 
 30.80 
 
 30.17 
 
 32.92 
 
 28.50 
 
 30.49 
 
 30.43 
 
 27-57 
 
 30.81 
 
 31.62 
 
 28.956 
 
 30.49 
 
 31-65 
 
 combined 
 
 1.68 
 
 I-3I 
 
 3.20 
 
 1.64 
 
 1. 18 
 
 1. 19 
 
 2.45 
 
 I-I3 
 
 1.86 
 
 1.923 
 
 1. 21 
 
 2.083 
 
 ^The 'constant error' is the difference between the standard distance (30 
 cm. ) and the ' average reproduction ' — the latter being the average of the actual 
 estimates made. Thus the ' average reproduction ' for the three estimates 33, 
 28 and 31 would be 30.67 ; the ' constant error ' 0.67. 
 
 ^'Variability' (^the 'crude variable error') was obtained by adding the 
 amount of variation from the standard (30 cm.), regardless of its sign, and divid- 
 ing by the number of cases considered ; thus the ' variability ' for the three 
 judgments 33, 28 and 31 would be 2. 
 
 3 " All types of suggestion combined " excludes throughout estimates with 
 no suggestion. 
 
THE REPRODUCTION OF DISTANCE. 
 
 273 
 
 Table II. 
 
 As Regards the Average Reproductions. 
 I. Average Reproductions Compared with the Actual Distance Exposed. 
 
 Subject. 
 
 X 
 
 V 
 
 First 25 Judg- 
 ments. 
 
 Reprod. Dist. > 
 
 " > 
 
 (except ' no sug- 
 gestion ') 
 Reprod. Dist. > 
 
 Second 25 Judg- 
 ments. 
 
 Reprod. Dist. < 
 
 > 
 
 Third 25 Judg- 
 ments. 
 
 Reprod. Dist. < 
 " > 
 
 > 
 
 Entire 75 Judg- 
 ments. 
 
 Reprod. Dist. < 
 
 " > 
 
 2. Average Reproductions with no Suggestion Compared with Average Re- 
 productions with Suggestion of any Kind. 
 
 X 
 
 no sug. > 
 
 no sug. ■< 
 
 no sug. ■< 
 
 no sug. < 
 
 V 
 
 " " <^ 
 
 " " < 
 
 " " < 
 
 " " < 
 
 
 (except 3 affirm. 
 
 (except visual -f 
 
 (except visual -|- 
 
 
 
 cases and visual — ) 
 
 and auto. -j- and — ) 
 
 and vocal + ) 
 
 
 z 
 
 no sug. < 
 
 no sug. < 
 
 (except vocal + 
 
 auto. + ) 
 
 no sug. •< 
 
 (except visual -)- 
 
 vocal + ) 
 
 " " < 
 
 3. Ave7'age Reproductions with Affirmative Suggestion Compared with 
 Average Reproduction with Negative Sztggestion. 
 
 X 
 
 Y 
 
 vis. + > vis. — 
 voc. + <C voc — 
 auto. -f- <^ auto. - 
 
 vis. + > vis. — 
 voc. + <; voc. — 
 auto . + <^ auto. — 
 
 vis. -f > vis. — 
 voc. + <^ voc. — 
 auto. -f> auto. — 
 
 vis. + < vis. — 
 voc. + <^ voc. — 
 auto. +> auto.— 
 
 vis. + < vis. — 
 voc. + <^ voc. — 
 auto. -|-<; auto. - 
 
 vis. + << vis. — 
 voc. -\- < voc. — 
 auto. + < auto. - 
 
 vis. + < vis. — 
 voc. 4- < voc. — 
 auto. -|-<C auto.— 
 
 vis. + <^ vis. — 
 voc . + <C voc. — 
 auto. + <; auto.— 
 
 vis. + < vis. — 
 voc. + <; voc. — 
 auto. + > auto. - 
 
 vis. + < vis. — 
 voc. + <C voc. — 
 auto. -|-<Cauto.— 
 
 vis. + <C vis. — 
 voc. -f <^ voc. — 
 auto. + < auto. - 
 
 vis. -f- <C vis. — 
 voc. + <^ voc. — 
 auto. + < auto. - 
 
 As Regards Variability. 
 
 4. Variability when there was no Suggestion Compared with that when there 
 was Suggestion of any kind. 
 
 Subject. 
 
 X 
 
 First 25 Judg- 
 ments. 
 
 no sug. > (ex- 
 cept vocal — 
 and auto.+ ) 
 
 no sug. > 
 
 Second 25 Judg- 
 ments. 
 
 no sug. < 
 
 no sug. < (ex- 
 cept visual + 
 and auto, -f) 
 
 no sug. > 
 
 Third 25 Judg- 
 ments. 
 
 no sug. < 
 
 no sug. < (ex- 
 cept visual -|-) 
 
 no sug. < (ex- 
 cept visual +) 
 
 Entire 75 Judg- 
 ments. 
 
 no sug. < 
 
 no sug. < (ex- 
 cept visual +, 
 vocal +, auto 
 
 + ) 
 no sug. < 
 
274 
 
 GRA CE MILDRED JONES. 
 
 Table II. Continued. 
 
 Vanability when there was Affirmative Suggestion Compared with that 
 when there was Negative Suggestion. 
 
 X 
 
 Y 
 
 vis. + < vis. — 
 voc. + < voc- 
 auto. + >auto. 
 
 vis. + <vis.— 
 voc. -j- < voc. - 
 auto.+ < auto. 
 
 vis. + < vis. — 
 voc.-j- < voc. — 
 auto.-|-< auto. 
 
 vis. + < vis.^ 
 voc. + < voc. — 
 auto. + > auto.— 
 
 vis. + < vis. — 
 VOC.4- < voc. — 
 auto. -}-< auto.— 
 
 vis. + < vis. — 
 voc. + < voc. — 
 auto. +< auto. — 
 
 vis. +< vis. — 
 voc. + >'voc. — 
 auto, -j- < auto.- 
 
 vis. + < vis. — 
 voc. + < voc. — 
 auto. +< auto.- 
 
 vis. + < vis. — 
 voc. + < voc. — 
 auto, -f < auto.- 
 
 vis. + < vis. — 
 voc. + < voc. - 
 auto. -|-< auto. 
 
 vis. + < vis. — 
 voc. -f- < voc- 
 auto. 4-<auto.- 
 
 vis. + < vis. — 
 voc. + < voc. - 
 auto. -t- <auto.- 
 
 In the portion of Table I. which presents the averages for 
 the three successive series of twenty-five judgments, as we might 
 expect, this general contrast in the effect of affirmative and 
 negative suggestions appears somewhat less regularly ; yet the 
 general result of combining the entire 75 judgments under any 
 one type of suggestion is seen to be fairly well distributed over 
 these smaller series. 
 
 Thus in the averages for the first series of twenty-five esti- 
 mates seven out of the twenty-four groups showed a reversed 
 effect for the affirmative and negative suggestions, that is, the 
 negative had less average error or variability than the affirma- 
 tive ; five of these irregularities were as regards the error, the 
 other two as regards the variability. In the second series of 
 twenty-five estimates three of the twenty-four groups were irreg- 
 ular, one in respect to the error, the other two in respect to the 
 variability. In the third series of twenty-five estimates, three 
 irregularities out of the twenty-four groups again occurred, two 
 as regards the error and one as regards the variability. 
 
 Accordingly, out of the sevent3^-two groups, when the judg- 
 ments were considered in series of twenty-five, there were thir- 
 teen irregular groups. Of these thirteen irregularities seven 
 were with the ' auto ' type of suggestion, three were with the 
 visual, two with the vocal, and one appeared in the comparison 
 of * affirmative suggestions combined ' and ' negative sugges- 
 tions combined,' in the first twenty-five estimates. 
 
 As regards the smaller constant error in the estimates made 
 with no suggestion than with those where there was suggestion, 
 
THE REPRODUCTION OF DISTANCE. 275 
 
 the results apparent in the combined seventy-five judgments 
 appear also in each of the series of twenty-five judgments, save 
 for subject X in the first series. As regards the smaller varia- 
 bility with no suggestion, exceptions occur in both the first and 
 second series of twenty-five judgments, but none in the third 
 series. 
 
 In view of the fact that the judgments made under sugges- 
 tion whether affirmative or negative show so frequently an 
 increase in variability and error beyond that in the judgments 
 made without suggestion, we may infer that suggestion does in 
 itself, and apart from the actual * contents ' of the suggestion, 
 effect some change in the reproduction of distance. 
 
 But it is also significant that the suggestion acts to a consid- 
 erable extent in a direction corresponding to the actual ' con- 
 tents ' of the suggestion given; /. e., the error and variability 
 under suggestions of ability were almost always less than when 
 suggestions of inability were made. 
 
 Previous experimenters found that one subject differed from 
 another radically in the degree and nature of the change which 
 suggestion produced. This is true only within somewhat narrow 
 limits, in the present experiments. The three subjects showed 
 the same significant tendencies in responding to suggestion ; that 
 is, with each, the suggestions of ability produced generally less 
 error and less variability than did the suggestions of inability ; 
 and estimates with no suggestion were in each case still nearer 
 the standard. The only difference lay in the fact that with two 
 of the subjects there was a constant tendency to lengthen, with 
 the other subject to shorten, the reproductions of the standard 
 interval of 30 cm. And this constant error, whatever its direction, 
 was increased by suggestions, especially by those of ' inability.' 
 It would be unjustifiable to say that one observer showed more 
 susceptibility to suggestion than another merely upon the ground 
 of a different direction or a different absolute amount in his 
 departure from the standard. Rather the subjects should be 
 compared upon a basis of the change in the amount or direction 
 of the errors or variability according as suggestions were present 
 or absent, or according as one form of suggestion or another 
 was employed. Upon this basis (see Table III.) there appears 
 some difference between the three subjects. 
 
276 GRACE MILDRED JONES. 
 
 Table III. 
 
 Order of the Effectiveness of Suggestion. 
 
 Based upon seventy-five judgments for each type of suggestion. 
 
 /. As 3feasured by the Change in the Average Reproductioti. 
 
 (The types of suggestion decrease in effectiveness from left to right.) 
 
 Subject. 
 
 X Voc. — Vis. — Vis. + Auto. — Auto. + Voc. + No suggestion 
 
 Y Voc. — Vis. — Vis. + Auto. — Auto. + Voc. + No suggestion 
 Z Voc. — Vis. — Auto. — Auto. + Vis. + Voc. + No suggestion 
 
 //. As Pleasured by the Change in Variability. 
 
 (The types of suggestion decrease in effectiveness from left to right.) 
 Subject. 
 
 X Vis. — Vis. + Voc. — Auto. — Auto. + Voc. + No suggestion 
 
 Y Vis. — Auto. — Voc. — No sug. Voc. + Vis. + Auto. + 
 
 Z Voc. — Vis. — Auto. — Vis, + Voc. + Auto. + No suggestion 
 
 Bell in his experiment notes that the effect of suggestion 
 decreased with repetition. This seems to be only partly, if at 
 all, true here. If the fact that suggestions of ability produce 
 less error, and suggestions of inability greater error in the re- 
 production of distance attests anything as to the power of sug- 
 gestion this experiment shows that the susceptibility more 
 regularly occurs with repetition, since as the experiment pro- 
 ceeds there occur fewer groups where this effect is reversed. 
 Table I. shows seven irregularities in this respect in the first 
 series of twenty-five estimates, and three each in the second and 
 the third series of twenty-five estimates. Apart from irregu- 
 larity, the absolute amount of the difference between ' affirma- 
 tive suggestions combined' and ' negative suggestions combined ' 
 shows in the case of Subject X a uniform increase in the suc- 
 cessive series of twenty-five judgments ; and the same is true 
 of the difference between ' no' suggestion ' and ' all types of 
 suggestion combined.' With the other subjects there is neither 
 a uniform increase nor decrease. 
 
 The purpose of the experiment was only in part to investigate 
 the effect of suggestion in general ; to determine the relative 
 influence of the different tyfes of suggestion was equally the 
 purpose. 
 
 In Tables III. and IV. is set forth the relative strength or 
 effectiveness of these different types of suggestion. It there 
 appears that for each of the subjects the negative suggestions 
 
THE REPRODUCTION OF DISTANCE. 
 
 Table IV. 
 
 277 
 
 Type of Suggestions. 
 
 Ratios of Reproductions with Sug- 
 gestion to Reproductions With- 
 out. Based upon the Constant 
 Error in Reproduction and also 
 upon the Variability ; I,atter in 
 Parentheses. 
 
 Subject 
 
 Ratios of Reproductions 
 with Suggestion to 
 the Actual Standard 
 (30cm.). Based upon 
 the Error in Repro- 
 duction. 
 
 Subject 
 
 
 X. 
 
 y- 
 
 z. 
 
 X. 
 
 K. 
 
 Z. 
 
 All types of suggestion com- 
 bined. (450 reproductions) 
 
 Affirmative suggestions com- 
 bined. (225 reproductions) 
 
 Negative suggestions com- 
 bined. (225 reproductions) 
 
 Visual suggestions com- 
 bined. (150 reproductions) 
 
 Vocal suggestions combined. 
 (150 reproductions) 
 
 Auto, suggestions combined. 
 (150 reproductions) 
 
 .971 
 
 (I-I74) 
 .982 
 
 (i^i25) 
 
 •959 
 
 (1.222) 
 
 -970 
 (1.280) 
 
 .964 
 (1.088) 
 
 •979 
 (i^i54) 
 
 1.008 
 
 (1-051) 
 1.005 
 
 (•911) 
 
 l.OIO 
 
 (1.192) 
 
 1.008 
 
 (1. 104) 
 
 l.OIO 
 
 (1-055) 
 1.005 
 
 (-997) 
 
 1.007 
 (1.074) 
 
 1.005 
 (I. 017) 
 
 l.OIO 
 
 (1-131) 
 
 1.008 
 
 (r-083) 
 
 I.C06 
 
 (1.078) 
 
 I.ooS 
 (1-059) 
 
 -957 
 .968 
 .946 
 .956 
 •950 
 •965 
 
 1. 019 
 1. 016 
 1.022 
 1. 019 
 1. 021 
 1. 016 
 
 1-054 
 1.052 
 
 1-057 
 1-055 
 1-053 
 1^055 
 
 (suggestions of inability) were about twice as effective as were 
 the positive suggestions (suggestions of ability). Moreover for 
 each subject the vocal negative suggestions were the most effec- 
 tive of all as measured by the constant change in the average 
 reproduction. As measured by the variability, the visual nega- 
 tive suggestions were stronger. With all the subjects the vocal 
 positive suggestions, on the other hand, had the least influence 
 upon the average reproduction ; while upon the variability the 
 * auto ' positive type was among those having the weakest 
 influence. 
 
 As suggestions of ability and inability appeared to bring 
 about an increase in the constant error and in the variability the 
 question was raised as to whether the results were due merely to 
 the distraction which the suggestions produced, and not at all 
 to their inherent ' content ' or ideas. It hardly seemed that 
 such a theory could be fully justified, for it would not account 
 for the fact that different types of suggestion had regularly 
 produced different effects — effects consistent with the ' content' 
 of the suggestion. However, seventy-five additional tests were 
 made on each of the three subjects, in which the pegs were ex- 
 posed and the reproductions made while the observer counted 
 aloud the strokes of a metronome, swinging at five different 
 rates, in order that the counting might more likely act as a dis- 
 
278 
 
 GRACE MILDRED JONES. 
 
 traction and not become a merely mechanical operation. The 
 other conditions were identical with those in the tests made for 
 suggestibility. 
 
 Table V. 
 Results for Estimates made under Distraction. 
 
 
 Average Reproductions of the Standard Distance together with the Variability. 
 
 Subject. 
 
 Averages for First 
 
 Averages for Second 
 
 Averages for Third 
 
 Averages for Com- 
 
 
 25 Judgments. 
 
 25 Judgments. 
 
 25 Judgments. 
 
 bined 75 Judgments. 
 
 X 
 
 28.48 
 
 28.32 
 
 28.12 
 
 28.31 
 
 1.68 
 
 1.64 
 
 1.88 
 
 1-73 
 
 V 
 
 29.86 
 
 29.38 
 
 29-15 
 
 29.48 
 
 ■94 
 
 .86 
 
 •93 
 
 .89 
 
 z 
 
 29. tS 
 
 29.14 
 
 31-65 
 
 29.92 
 
 1.02 
 
 1-54 
 
 1.88 
 
 1.46 
 
 The variability is thus seen to be, on the average, less than 
 when suggestions were offered, and for the most of the subjects 
 less even than in the cases where no suggestion was made. As 
 for the average reproductions, the two subjects whose esti- 
 mate of the distance had been constantly greater than the 
 standard in the previous experiment now had a tendency to make 
 it less than the standard. The other subject whose tendency 
 had been to underestimate the standard interval now had a ten- 
 dency to make it still shorter. 
 
 The fact that the results with distraction differed in these 
 respects from the results with different types of suggestion indi- 
 cates that at least with two of the three subjects the peculiar 
 effect of these suggestions is not due solely nor even pre- 
 dominately to any distraction which may have inhered in them. 
 
 Onl»ersitf of California 
 
 PsynliiilojKal aoratoi). 
 

 l^ 
 
 THE EFFECT OF VARIOUS TYPES OF SUGGESTION 
 UPON MUSCULAR ACTIVITY 
 
 BY EDW. K. STRONG, Jr., M.S. 
 
 Reprinted from the Psychoi^ogical Review, July, 1910, 
 Vol. XVII, pp. 229-259. 
 
 Oolvefsify of Oaiifeiii- 
 
 
[Reprinted from The Psychological Review, Vol. XVII., No. 4, July, 191 0.] 
 
 XII. The Effect of Various Types of Suggestion 
 UPON Muscular Activity. 
 
 BY EDW. K. STRONG, Jr., M.S. 
 
 The purpose of the experiment here reported was to discover 
 how far and in what manner maximum muscular activity may- 
 be affected by suggestions of various types. In all these the 
 subject was instructed not to oppose any resistance to the sug- 
 gestion nor on the other hand consciously to endeavor to carry 
 out the suggestions, but his attention and conscious effort 
 throughout was to be expended in exerting each time his maxi- 
 mum grip. Yet he was requested to maintain the suggestion in 
 consciousness until after his muscular effort. 
 
 Historical Review. 
 
 There is scarcely any literature which bears directly upon 
 the question under discussion in this paper. A number of 
 articles ^ which have appeared lately indicate that some atten- 
 tion is being given the subject, but neither their methods nor 
 their results have any direct relation to those of the present 
 investigation. As far as I am aware Brand is the pioneer in 
 this field of investigation. His experiment^ was performed in 
 this laboratory, and his purpose, as he states it, was " to find 
 out how far and in what direction the visual estimation of a 
 linear magnitude could be affected by suggestion of certain pos- 
 sible errors in such estimation, the subject knowing that the 
 
 ^Triplet, ' Dynamogenic Factors ia Pace-making and Competition,' Amer- 
 four. of Psych. y IX., 507-533. Small, 'The Suggestibility of Children,' Ped. 
 Sent., IV., 182. Binet, 'La suggestibility,' L'antiee psych., V., 99. Pearce, 
 'Normal Motor Suggestibility,' Psych. Rev., IX., 348. Smith and Sowton, 
 ' Observations on Spatial Contrast and Confluence in Visual Perception,' Brit. 
 Jour. Psych., II., J96-219. A very full discussion of all but the first accom- 
 panies the article of Bell (' The Effect of Suggestion upon the Reproduction of 
 Triangles and of Point Distances') in the Avier. Jour, of Psych., XIX., 504. 
 
 2 'The Effect of Verbal Suggestion upon the Estimation of Linear Magni- 
 tudes,' Psych. Rev., XII., 1905, 41-49.3 
 
 279 
 
 OnlvffsiH' ^f California 
 
 Psyotiologicai liboratoi). 
 
28o EBJV. K. STRONG. 
 
 suggestions were purely arbitrary, /. e.^ that they had no refer- 
 ence to any foreseen tendency to err in any direction." ^ 
 
 The eight different suggestions used by Brand in his experi- 
 ment were printed upon white cardboard in letters 1.2 cm, high. 
 The conductor presented them to the subject by displaying the 
 cardboard for a moment. After the suggestion had been pre- 
 sented the conductor displayed two small objects upon his frame 
 and then called upon the subject to respond by setting up his two 
 similar objects upon his own frame at a distance from each other 
 approximating as nearly as possible that of the original objects. 
 
 I have reduced the results as given in his tables to per- 
 centages of the respective standards. 
 
 The following table gives the total results of Subject 'C,' 
 
 eliminating the first group of experiments, since their variation 
 
 is more than ten per cent, from the standard, due probably to 
 
 lack of practice. 
 
 Table I. 
 
 Suggestion. No. of Sum of Result in 
 
 Judgments. Standards. per cent. 
 
 Zwp fjvic bgzx asye 49 1,258 100.5 
 
 L,ife is real where 49 1.258 99.5 
 
 Don't make too long 49 1,258 loi.o 
 
 Don't make too short 49 1,258 loi.o 
 
 Make short 104 2,632 99.5 
 
 Makelong 104 2,632 102.0 
 
 And the following table gives the total results for Subject 
 ' Y,' the first group of data having been likewise eliminated. 
 
 Table II. 
 
 Suggestion. No. of Sum of Result in 
 
 Judgments. Standards. per cent. 
 
 Zwp fjvic bgzx asye 49 1,086 91.0 
 
 Life is real where 49 1,086 90.0 
 
 Don't make too long 84 1,810 92.0 
 
 Don't make too short 84 1,810 92.5 
 
 Make short 100 2,400 94.0 
 
 Makelong 100 2,400 94.0 
 
 1 It is just at this point that suggestions as experimented upon in Bell's 
 (see page 5) and Brand's work and in my own differ from the others. As Bell 
 puts it ; " The most potent factor without doubt in cases of suggestion is the 
 arousal of an attitude of general expectancy." This factor has been utilized in 
 the experiments of others, but is so far as possible eliminated in these three, for 
 here the subject was particularly instructed that he was not to respond con- 
 sciously to the suggestion but to endeavor consciously to exert his maximum 
 
 grip- 
 
EFFECT OF SUGGESTION UPON MUSCULAR ACTIVITY. 281 
 
 From these tables I do not feel that any clear-cut deductions 
 can be made, with the possible exception that the two brief sug- 
 gestions ' Make short ' and ' Make long ' tend more than the 
 other suggestions to make the reproduced distance greater in 
 magnitude, and the two suggestions ' Don't make too long ' and 
 * Don't make too short ' tend to a less degree to have the same 
 effect. 
 
 In Table III. Brand has brought together from group D (or 
 the last group of experiments with both subjects) the totals for 
 all the suggestions containing the word ' long' in one column 
 and all those containing the word ' short' in another column, for 
 comparison. The percentages as given below were inserted by 
 myself. 
 
 Table III. 
 
 c„K-„„(. No. of Sum of <T^.,^> Per < ct,«..f > Per 
 
 Subject. Judgments. Standards. ^"'^e- cent. ^hort.' ^^^^ 
 
 'C 58 1,628 1.702.3 104.5 1)644.4 loi.o 
 
 *Y' 36 5S0 556.3 95.5 542.6 93.5 
 
 If compiled from all four of the groups instead of group D 
 alone we have the following. 
 
 Table IV. 
 
 e,,K;^„» No. of Sum of «t«^^> Per <ct,^..t' Per 
 
 Subject. Judgments. Standards. ^°'^e- cent. ^^o'^*- cent. 
 
 'C 207 4,932 5,095-8 103.0 5.052.2 102.5 
 
 •Y' 189 4,294 4,008.2 93.8 4.013-2 93.9 
 
 Here we have no superiority of the ' long ' mottoes over the 
 ' short ' mottoes, except with the one subject. 
 
 Let us now turn to the second part of his experiment. Here 
 but three suggestions were used : ' long,' ' short ' and ' XXXX.' 
 The latter was used as a check or neutral. Quoting from him : 
 " Four subjects were employed and the results were not very uni- 
 form, two of the subjects showing no decided tendency towards 
 anything resembling a constant effect, while the other two sub- 
 jects showed a clear general constancy of considerable difference 
 throughout." 
 
 In conclusion it seems to me that one cannot point with any 
 emphasis to any direct effect from the above varied suggestions 
 upon estimation of distance except (i) that ' long ' suggestions 
 may consistently affect one person more than corresponding 
 
282 EDW. K. STRONG. 
 
 * short' ones ; (2) that the reverse effect may be produced upon 
 a second person ; and (3) that there may be no appreciable 
 effect of one or the other upon a third person. 
 
 In Bell's experiment^ two types of suggestion were used — 
 the auditory and the visual. For the former such as ' make high,' 
 
 * make low,' 'make high enough,' etc., or simply 'high' and 
 ' low ' were used, being spoken by the conductor just before the 
 presentation of the object to be reacted upon. For the visual 
 suggestion a diamond-shaped figure 20 cm. long and 4 cm. wide 
 was shown to the subject. When displayed in a vertical posi- 
 tion it was thought that it might serve as a ' high ' suggestion, 
 being much taller than an}^ other figure shown. Likewise when 
 shown in a horizontal position it was called a ' low ' suggestion. 
 (As far as I am aware the subject was not informed what this 
 visual suggestion was intended to suggest. It may not then 
 have had an equal effect upon the different subjects.) 
 
 The forms chosen for reproduction were : (i) triangles of 
 different shapes and heights and (2) vertical point distances as 
 shown by (a) a dot above the center of a base line and {b) a dot 
 above another dot. 
 
 Under the first group (triangles of different shapes and 
 heights) ten triangles were used, of the same base (10 mm.), but 
 of different heights and shapes, and varying from 49 to 100 mm. 
 in altitude. The work was so carried on that nine reproduc- 
 tions of each triangle were made with each kind of suggestion 
 {i. e., auditory and visual). Three of the nine were reproduced 
 with ' high ' suggestions, three with ' low ' suggestions, and three 
 without any suggestion. The altitude of the reproduced triangle 
 was compared wiih the standard, and the difference expressed in 
 millimeters as a positive or negative error. But the weakness 
 of his experiment lies in the small number of observations per 
 subject per triangle per suggestion, /. e., tJwee in number. 
 Averages drawn from so few observations are hardly of greatest 
 weight. 
 
 Bell concludes " that in general the suggestions do affect 
 the reproduction of the triangles ; that the auditory suggestion 
 
 1 ' The Effect of Suggestion upon the Reproduction of Triangles and of 
 Point Distances/ Ainer.Jour. of Psych., XIX., 190S, 504. 
 
EFFECT OF SUGGESTION UPON MUSCULAR ACTIVITY. 283 
 
 is more effective than the visual ; and that in the auditory set 
 the ' low ' suggestion is more effective than the ' high.' " Upon 
 looking at the subjects individually we find they have reacted 
 differently. Subject ' B ' alone showed striking susceptibility to 
 the suggestion in all the cases. Subjects 'A,' 'C and 'D' 
 with the auditory suggestions and Subject ' E ' with the visual 
 suggestions, estimated the apex of the triangles below the stand- 
 ard when given either ' high ' or ' low ' suggestions. Through- 
 out the experiment susceptibility to ' low ' suggestions was more 
 general and more uniform than to ' high ' suggestions. 
 
 Under the second group (vertical point distances) the dot- 
 above-line experiment was completed with auditory suggestions 
 and the dot-above-dot experiment with visual suggestions. Bell 
 in commenting upon his results states that there was little indi- 
 cation that the suggestions had any constant effect: with sub- 
 jects ' C ' and * D ' the ' high ' and ' low ' suggestions are both 
 lower than the standard, the ' low ' the lowest ; while with sub- 
 jects ' E ' and ' F ' the ' high ' and ' low ' suggestions are both 
 higher than the standard. 
 
 Description of the Present Experiment. 
 
 The series of experiments carried on as described below can 
 be divided into two parts, the first part consisting of those ex- 
 periments which were performed during the months from Sep- 
 tember to December, 1908, and the second part consisting of 
 those which were performed during the months from January to 
 April, 1909. 
 
 The general plan of the experiment was to give the subject 
 a suggestion, and then have him respond each time with his 
 maximum grip. Collin's elliptical form of dynamometer was 
 used and from it an expression in kilograms was obtained of his 
 muscular activity. 
 
 The subject was seated in a chair which was provided with 
 two flat arms about two and a half inches wide which extended 
 as far forward as the front edge of the seat. The subject rested 
 his arms from the elbow to the wrist upon these arms of the 
 chair. When actually gripping the dynamometer the palm of 
 his hand was uppermost. In the intervals he was allowed to 
 
284 BDIV. K. STRONG. 
 
 rest his hand as he chose. The conductor sat at a small table. 
 On the edge of this table between the subject and the conductor 
 a large upright black screen was placed in such a manner that 
 the subject could not see anything upon the table ; nor could he 
 see the conductor. 
 
 Once every twenty seconds, until the series with one hand 
 was completed, the subject gripped the dynamometer with his 
 maximum force. The exact procedure was as follows. When 
 the second-hand of the watch indicated the moment of presen- 
 tation, the suggestion was given by the conductor. The 
 dynamometer was then placed in the subject's hand. As soon 
 as the latter had responded with his maximum grip the con- 
 ductor took the instrument from his hand, noted the reading, 
 and then awaited the next moment of presentation. 
 
 In all there w^ere seven suggestions offered. They might be 
 classified as follows : 
 
 I. Atidito7'y Suggestions. 
 
 1. Positive, "Now you can make it stronger than usual." 
 
 2. Negative. " Now you can't make it as strong as usual." 
 These suggestions were presented vocally by the conductor. 
 
 II. Visual Suggestions. 
 
 1. Positive. A plus (-|-) sign 0.4 inches in size displayed 
 upon a piece of cardboard two inches square. 
 
 2. Negative. A minus (— ) sign 0.4 inches in size displayed 
 upon a piece of cardboard two inches square. 
 
 In giving these suggestions the conductor placed the card- 
 board upon the corner of the table in front of the subject. 
 
 At the commencement of the experiment each subject was 
 told that the plus (-|-) sign was meant to suggest to him that he 
 could make his grip stronger than usual and the minus (— ) sign 
 was meant to suggest that he could not make it as strong as 
 usual. These signs were consequently visual suggestions de- 
 pending on previous vocal instruction. 
 
 III. Auto -suoorest ions . Here the conductor announced in 
 the same tone and manner as in presenting the Auditory Sug- 
 gestions "Now you can make a suggestion of your own." The 
 subject understood by this that he was at liberty to suggest to him- 
 self either the positive or negative suggestion and to designate 
 
EFFECT OF SUGGESTION UPON MUSCULAR ACTIVITY. 285 
 
 his choice to the conductor by audibly announcing it. In this 
 case as soon as the subject had announced his suggestion the 
 dynamometer was handed him and the experiments continued 
 as usual. 
 
 1. Positive. (After suggestion by the conductor, as above.) 
 " Now I can make it stronger than usual," spoken by the 
 subject. 
 
 2. Negative. (After suggestion by the conductor, as above.) 
 "Now I can't make it as strong as usual," spoken by the 
 subject. 
 
 IV. Neutral '■Suggestion.'' This consisted of the announce- 
 ment by the conductor of, ' Now, neutral,' and was intended to 
 act merely as a check and guide to what would be the exertion 
 if no suggestion of any sort were given. 
 
 In the earlier experiments a series consisted of fifty-six 
 experiments or readings, twenty-eight with each hand. These 
 twenty-eight in turn consisted of four each of the seven different 
 suggestions. These twenty-eight were presented to the subject 
 in a haphazard arrangement previously determined upon. All 
 subjects were given the same haphazard arrangements and in 
 the same order, so that direct comparisons between them could 
 be made. The right hand in every case was experimented 
 upon first. After four days' work with each subject, ten 
 neutrals instead of four were introduced, thus making a day's 
 work or series consist of thirty-four experiments instead of 
 twenty-eight. Besides these twenty-eight or thirty-four experi- 
 ments there were always two extra neutrals at the start which 
 were for the purpose of practice and were always discarded. 
 
 A day's work with subject * B ' consisted of two series during 
 one hour, — that is to say, of fifty-six experiments with each 
 hand taken in this manner : twenty-eight with the right hand, 
 then twenty-eight with the left hand, then twenty-eight with the 
 right, and finally twenty-eight more with the left. A day's 
 work with subjects *J' and * W' consisted of only one series 
 during one hour. During the second term but one series per 
 day was taken with any one of the three subjects. It should 
 also be stated here that all three subjects were familiar with 
 experimental work. 
 
286 EDW. K. STRONG. 
 
 The procedure during the second term was exactly the same 
 as in the first term except for the following. Instead of seven 
 suggestions nine were employed. The two auto-suggestions 
 were omitted and the following four added. Two auditory sug- 
 gestions consisting of ' Now, plus ' and ' Now, minus ' to corre- 
 spond to the two visual suggestions employed during the first 
 term. Also two visual suggestions consisting of the mottoes : 
 **Now 3''ou can make it stronger than usual " and " Now you 
 can't make it as strong as usual" printed on cards 5.5 x 1.25 
 inches. These visual suggestions were to correspond to the 
 auditory suggestions employed during the first term. More- 
 over the visual suggestions (-f) and (— ) were presented on cards 
 similar to those just described, instead of on cards two inches 
 square. Instead of 28 or 34 experiments on each hand per day 
 there were 42 such experiments. These 42 consisted of four 
 each of the eight suggestions and ten of the neutrals, arranged 
 as before in a haphazard manner. During the second term the 
 right hand was not experimented upon first each da}'', but only 
 in alternation with the left hand. 
 
 The nine suggestions of the second term and the two auto- 
 suggestions of the first term will be referred to in the tables by 
 the following set of symbols. 
 
 I. Auditory Suggestions — in quotation marks. 
 
 ' Can ' means " Now you can make it stronger than usual." 
 * Can't' means *' Now you can't make it as strong as usual." 
 ' + ' means '* Now plus." 
 ' — ' means " Now minus." 
 
 II. Visual Suggestions — in brackets. 
 
 (Can) means the motto, " Now you can make it stronger 
 
 than usual " printed on a card. 
 (Can't) means the motto, "Now you can't make it as 
 
 strong as usual " printed on a card. 
 (-}-) means the symbol ' + ' printed on a card. 
 ( — ) means the symbol ' — ' printed on a card. 
 
 III. Auto-stiggestions. 
 
 4- Auto means " Now I can make it stronger than usual," 
 
 spoken by the subject. 
 — Auto means " Now I can't make it as strong as usual," 
 
 spoken by the subject. 
 
EFFECT OF SUGGESTION UPON MUSCULAR ACTIVITY. 2S7 
 
 IV. Neutral ' Suggestion.'' 
 
 'N' means "Now, neutral." 
 
 The Results. 
 In the following two tables there are presented the averages 
 of 48 experiments for each type of suggestion with either hand 
 of the three subjects, the numbers indicating in kilograms the 
 maximal grip. 
 
 Table V. 
 Results for the First Term. 
 
 The numbers for the first six suggestions under Subjects ' B ' and 'J ' are an 
 average of 48 results, and under Subject ' W ' are an average of 24 results. The 
 neutrals under Subjects 'B ' and 'J' are an average of 96 results while under 
 Subject ' W ' they are an average of 36 results. 
 
 Suggestions. 
 
 Subject 'B.' 
 
 Subject 'J.' 
 
 Subject 'W.' 
 
 Right. 
 
 Left. 
 
 Right. 
 
 Left. 
 
 Right. 
 
 Left. 
 
 'Can' 
 ' Can't ' 
 
 + Auto. 
 — Auto. 
 
 38.8 
 38.4 
 38.9 
 38.6 
 
 39.7 
 39-0 
 
 29.6 
 28.9 
 29.9 
 29-3 
 29-5 
 29.9 
 
 17.2 
 17. 1 
 
 17.7 
 17. 1 
 
 17.5 
 17.I 
 
 I5-0 
 
 15-4 
 I5-0 
 14.8 
 15.2 
 15-3 
 
 33-1 
 33-3 
 33.8 
 33-5 
 33-5 
 33-6 
 
 23-7 
 23-4 
 24.4 
 24.4 
 24.2 
 25.6 
 
 Average 
 Neutral 
 
 38.9 
 39- 
 
 29-5 
 29.4 
 
 17.2 
 16.9 
 
 15- 1 
 I5-0 
 
 33-5 
 33-4 
 
 24-3 
 23-5 
 
 Average of all 
 
 38.9 
 
 29-5 
 
 I7.I 
 
 I5-I 
 
 33-5 
 
 23-9 
 
 Table VI. 
 Results for the Second Term. 
 
 The numbers for the first eight suggestions are an average of 48 trials 
 while those for the neutrals are an average of 120 trials. 
 
 Suggestions. 
 
 Subject 'B.' 
 
 Subject 'J.' 
 
 Subject 'W.' 
 
 Right. 
 
 Left. 
 
 Right. 
 
 Left. 
 
 Right. 
 
 Left. 
 
 'Can' 
 ' Can't ' 
 (Can) 
 (Can't) 
 
 ' + ' 
 < > 
 
 40.3 
 39-7 
 39-4 
 40.1 
 39-6 
 39-4 
 39-3 
 39-6 
 
 31.8 
 31-4 
 31.0 
 
 31-3 
 31.2 
 30.8 
 •31-3 
 31-3 
 
 16.9 
 16.9 
 16.9 
 16.8 
 16.7 
 16.7 
 16.9 
 16.7 
 
 15.9 
 16.3 
 16.4 
 
 15-9 
 16.2 
 • 16. 1 
 16.3 
 16.4 
 
 32.8 
 32.6 
 
 32.9 
 33-2 
 32.2 
 32.1 
 32.4 
 32.8 
 
 25.1 
 25-4 
 25-3 
 25.3 
 24.8 
 
 25-1 
 
 25.3 
 25-9 
 
 Average 
 
 Neutral 
 
 39-7 
 39-4 
 
 31-3 
 
 30.8 
 
 16.8 
 16.7 
 
 16.2 
 16.0 
 
 32.6 
 32.2 
 
 25-3 
 24.9 
 
 Average of all 
 
 39-5 
 
 3I-I 
 
 16.8 
 
 16. 1 
 
 32.5 
 
 25.2 
 
288 
 
 EDW. K. STRONG. 
 
 From these two tables we see very clearly that suggestion 
 as a whole heightens the maxima. In every case, except for the 
 right hand of subject ' B ' during the first term, the average of 
 the neutrals for any of the three subjects with either hand is 
 less than the corresponding average of all the other suggestions. 
 The exception can probably be explained by an introspection of 
 subject ' B ' on March i, when he stated that neutrals dX first 
 had a positive effect, that is to say, he felt that then was a time 
 to make a ' record.' 
 
 In the following two tables we have a statement of the mean 
 variation of the quantities entering into the preceding tables : 
 Table VII stating the mean variation of the quantities in Table 
 V, and Table VIII stating those of Table VI. 
 
 Mean Variation Table VII. (First Term.) 
 
 Suggestions. 
 
 Subject 'B.' 
 
 Subject 'J.' 
 
 Subject 'W.' 
 
 Right. 
 
 IvCft. 
 
 Right. 
 
 Left. 
 
 Right. 
 
 Left. 
 
 'Can' 
 'Can't' 
 ( + ) 
 (-) 
 
 + Auto. 
 — Auto. 
 
 1.88 
 2-34 
 2^59 
 2.29 
 2.21 
 1.74 
 
 2. .00 
 1.70 
 1.89 
 1.84 
 2.32 
 
 1.86 
 
 .86 
 
 •74 
 
 I. II 
 
 1.04 
 
 •93 
 
 •93 
 
 .96 
 
 .87 
 
 1.09 
 
 •83 
 .Si 
 .88 
 
 3-17 
 2.77 
 2.46 
 2.62 
 2.30 
 2.26 
 
 1.68 
 1.48 
 1. 71 
 1.70 
 1. 61 
 1.98 
 
 Average 
 Neutral 
 
 2.17 
 1.94 
 
 1-93 
 1.57 
 
 .93 
 .85 
 
 •91 
 
 .94 
 
 2.59 
 2.99 
 
 1.69 
 2.08 
 
 Average of all 
 
 2.14 
 
 1.88 
 
 .92 
 
 •91 
 
 2.65 
 
 i^75 
 
 Mean Variation Table VIII. (Second Term.) 
 
 Suggestions. 
 
 Subject ' B ' 
 
 Subject 'J' 
 
 Subject ' W ' 
 
 Right. 
 
 Left. 
 
 Right. 
 
 Left. 
 
 Right. 
 
 Left. 
 
 'Can' 
 ' Can't ' 
 (Can) 
 (Can't) 
 
 ' + ' 
 < 1 
 
 ( + ) 
 (-) 
 
 2.58 
 
 2.57 
 2.04 
 1.80 
 1.82 
 2.17 
 2.46 
 1.97 
 
 l^54 
 
 1.88 
 
 .80 
 
 •67 
 .80 
 .80 
 .87 
 •92 
 
 •63 
 -73 
 .76 
 .67 
 •79 
 •77 
 .81 
 .89 
 
 1.03 
 1. 01 
 
 •91 
 1.02 
 1.08 
 
 I-I3 
 1.20 
 
 I- 13 
 
 2.17 
 2.62 
 2.06 
 2.38 
 2.32 
 2.61 
 2. II 
 2.II 
 
 2.32 
 2.31 
 2.19 
 
 2^39 
 2.24 
 1.97 
 2.04 
 2.06 
 
 Average 
 Neutral 
 
 2.18 
 2.05 
 
 1.03 
 1.69 
 
 I. II 
 
 .76 
 .85 
 
 1.06 
 1. 12 
 
 2.29 
 2.37 
 
 2.19 
 2.50 
 
 Average of all 
 
 2.16 
 
 .77 
 
 1.07 
 
 2.31 
 
 2.22 
 
EFFECT OF SUGGESTION UPON MUSCULAR ACTIVITY. 
 
 589 
 
 In Table IX. we have a restatement of Table V., and in 
 Table X. restatement of Table VI. to show the effect respec- 
 tively of positive, negative and neutral suggestions upon the 
 three subjects. 
 
 From these tables it is evident that the negative suggestions 
 tend more than the positive suggestions with subject ' W ' to 
 heighten the maxima, and this is especially true with his left 
 hand. But with the other two subjects the positive suggestions 
 as a general rule are superior to the negative in this respect. 
 However in all three cases the negative auto-suggestions with 
 the left hand are clearly superior to the positive in heightening 
 the maxima. Why this is the case is difficult to say. Possibly, 
 the subject feels that after audibly declaring that he can't make 
 it as strong as usual, he must exert greater effort in order to 
 neutralize the suggestion's effect and actually obtain his maxi- 
 mum. With the right hand, however, this tendency does not 
 appear, perhaps because of the hand's greater use and its con- 
 sequent greater fineness in discrimination. Indeed it appears 
 
 Table IX. 
 Subject 'B.' 
 
 
 With the Right Hand. 
 
 With the Left Hand. 
 
 
 Positive. 
 
 Negative. 
 
 Neutral. 
 
 Positive. 
 
 Negative. 
 
 Neutral. 
 
 Auditory 
 Visual 
 Auto. 
 Neutral 
 
 38.8 
 38.9 
 
 39-7 
 
 38.4 
 38.6 
 
 39- 
 
 39-0 
 
 29.6 
 29.9 
 29-5 
 
 28.9 
 
 29-3 
 29.9 
 
 29.4 
 
 Average 
 
 39-1 
 
 38.7 
 
 39-0 
 
 29.7 
 
 29.4 
 
 29.4 
 
 Subject ' J. 
 
 Auditory 
 
 Visual 
 
 Auto. 
 
 Neutral 
 
 Average 
 
 17.2 
 17.1 
 17-5 
 
 17-3 
 
 17.1 
 17.1 
 17.1 
 
 17.1 
 
 16.9 
 
 16.9 
 
 15.0 
 15-0 
 
 15-2 
 
 15.1 
 
 15.4 
 14.8 
 
 15-3 
 
 15-2 
 
 15.0 
 
 I5-0 
 
 Subject 'w.' 
 
 Auditory 
 Visual 
 Auto. 
 Neutral 
 
 Average 
 
 33.8 
 33-5 
 
 33-5 
 
 33-3 
 33-5 
 33-6 
 
 33-5 
 
 33-4 
 33-4 
 
 237 
 24.4 
 24.2 
 
 24.1 
 
 234 
 24.4 
 25.6 
 
 24-5 
 
 23-5 
 23-5 
 
290 
 
 £DIV. K. STRONG. 
 
 Table X. 
 Subject ' B.' 
 
 
 With the Right Hand. 
 
 With 
 
 the I,eft Hand. 
 
 
 Positive. 
 
 Negative. 
 
 Neutral. 
 
 Positive. 
 
 Negative. 
 
 Neutral.; 
 
 Auditory can-can 't 
 Visual can-can't 
 Auditory + and — 
 Visual + and — 
 Neutral 
 
 40.3 
 39-4 
 39-6 
 39-3 
 
 39-7 
 40.1 
 
 39-4 
 39-6 
 
 39-4 
 
 31.8 
 31.0 
 31.2 
 31-3 
 
 314 
 31-3 
 30.8 
 31-3 
 
 30.8 
 
 Average 
 
 39-7 1 39-7 
 
 39-4 
 
 31-3 
 
 31.2 
 
 30.8 
 
 Subject 'J. ' 
 
 Auditory can-can't 
 Visual cau-cau't 
 Auditory -f and — 
 Visual + and — 
 Neutral 
 
 Average 
 
 16.9 
 16.9 
 16.7 
 16.9 
 
 16.9 
 
 16.9 
 16.S 
 16.7 
 16.7 
 
 16.8 
 
 16.7 
 
 16.7 
 
 15.9 
 16.4 
 16.2 
 16.3 
 
 16.2 
 
 16.3 
 
 15.9 
 16.1 
 16.4 
 
 16.1 
 
 16.0 
 
 16.0 
 
 Subject 'W. 
 
 Auditory can-can't 
 Visual can-can't 
 Auditory + and — 
 Visual + and — 
 Neutral 
 
 Average 
 
 32.8 
 
 32.9 
 32.2 
 
 324 
 
 32.6 
 
 32.6 
 
 33-2 
 32.1 
 32.8 
 
 32.7 
 
 32.2 
 
 25-1 
 
 25-3 
 24.8 
 
 25-3 
 
 254 
 25-3 
 25.1 
 25-9 
 
 32.2 
 
 25-1 
 
 25-5 
 
 24.9 
 
 24.9 
 
 true that the so-called maximum effort in this experiment is not 
 a real maximum exertion each time, but rather is an effort to 
 attain a sort of definite standard. The left hand is thus at a 
 disadvantage in maintaining its maximum, or definite standard, 
 because of its lesser use and inferior discrimination. 
 
 In Tables XI. and XII. we have still a different restatement 
 of Tables V. and VI. for the purpose of showing the effect of 
 particular types of suggestion. In these tables the figure placed 
 opposite each suggestion is the average of that type's positive 
 and negative suggestions taken together ; and the types are 
 arranged according to the magnitudes of the averages. 
 
 We must conclude from these tables that : (i) the auto-sug- 
 gestions tend most strongly of all the types of suggestion to 
 heighten the maxima ; (2) that during the first term the visual 
 suggestions were superior in this respect to the auditory sugges- 
 tions with subjects ' B ' and ' W,' and were inferior with subject 
 
EFFECT OF SUGGESTION UPON MUSCULAR ACTIVITY. 2C)I 
 
 Table XL 
 With the Right Hand. 
 
 Subject ' B.' 
 
 Subject ' J.' 
 
 Subject 'W.' 
 
 Auto. 39-35 
 Neutral 39.0 
 Visual 38.75 
 Auditory 38.6 
 
 Auto. 17.3 
 Auditory 17.15 
 Visual 17. 1 
 Neutral 16,9 
 
 Visual 33.65 
 Auto. 33.55 
 Neutral 33.4 
 Auditory 33.2 
 
 With the; Left Hand. 
 
 Auto. 29.7 
 
 Auto. 15.25 
 
 Auto. 24.9 
 
 Visual 29.6 
 
 Auditory 15.2 
 
 Visual 24.4 
 
 Neutral 29.4 
 
 Neutral 15.0 
 
 Auditory 23.55 
 
 Auditory 29.25 
 
 Visual 14.9 
 
 Neutral 23.5 
 
 Table XII. 
 With the Right Hand. 
 
 Subject ' B.' 
 
 Subject ' J.' 
 
 Subject 'W.' 
 
 Auditory Can-Can't 
 
 40.0 
 
 Auditory Can-Can't 
 
 16.9 
 
 Visual Can-Can't 
 
 33-1 
 
 Visual Can-Can't 
 
 3Q.8 
 
 Visual Can-Can't 
 
 16.9 
 
 Auditory Can-Can't 
 
 32.7 
 
 Auditory + and — 
 
 39-5 
 
 Auditory + and — 
 
 16.8 
 
 Visual -|- and — 
 
 32.6 
 
 Visual + and — 
 
 .39-4 
 
 Visual + and — 
 
 16.8 
 
 Neutral 
 
 32.2 
 
 Neutral 
 
 39-4 
 
 Neutral 
 
 16.7 
 
 Auditory + and — 
 
 32.1 
 
 With the Left Hand. 
 
 Auditory Can-Can't 
 
 31.6 
 
 Visual + and — 
 
 16.4 
 
 Visual + and — 
 
 25.6 
 
 Visual + and — 
 
 31-3 
 
 Visual Can-Can't 
 
 16.2 
 
 Visual Can-Can't 
 
 25.3 
 
 Visual Can-Can't 
 
 31.2 
 
 Auditory + and — 
 
 16.2 
 
 Auditory Can-Can't 
 
 25.2 
 
 Auditory -\- and — 
 
 31.0 
 
 Auditory Can-Can't 
 
 16.1 
 
 Auditory + and — 
 
 25.0 
 
 Neutral 
 
 30.8 
 
 Neutral 
 
 16.0 
 
 Neutral 
 
 24.9 
 
 'J,' while during the second term the visual suggestions were 
 superior with subject ' W ' and the left hand of subject ' J', and 
 were inferior with the right hand of subjects ' B ' and ' J ' ; and 
 (3) that during the second term the motto suggestions (^. g:, 
 " Now you can make it stronger than usual ") were superior 
 to the symbol suggestions (^. ^.j plus sign) in heightening the 
 maxima. 
 
 Before attempting any explanation of these results it should 
 be borne in mind that Miss G. M. Jones, working at the same 
 general problem outlined in this paper, and with two of the same 
 subjects, but upon the reproduction of distance instead of upon 
 maximal exertion, obtains the most accurate reproduction of dis- 
 tance with the neutral ' suggestion,' while the other suggestions, 
 
292 EDW. K. STRONG. 
 
 instead of aiding in the reproduction of distance, apparently 
 disturb the accuracy of such reproduction. (It is notable that 
 all three subjects were affected nearly alike in her experiftient 
 while there were such different effects with different subjects in 
 my own experiment, as well as in Brand's.) 
 
 Suggestion then affects the reproduction of distance by act- 
 ing as a disturbing factor, but aids, as my results show, when 
 applied to maximal muscular effort. From these two experi- 
 ments it seems probable that when accurate work is to be done 
 all suggestions prevent the best work ; but when mere amount 
 of muscular effort is called for, any arousal of the attention to 
 the work acts as a stimulant and enables the person to do better 
 than he would otherwise have done. This effect is also shown 
 by an incident which occurred with subject ' W.' Near the 
 close of the series with his left hand the experiments were in- 
 terrupted by a messenger who notified him that he was awaited 
 elsewhere. The eagerness to be through the experiment caused 
 a rise of approximately five kilograms, or eleven pounds, in his 
 grip for the remaining eight trials. 
 
 I have used the word ' attention ' in this connection because 
 I do not know a better, yet I arp not entirely satisfied that it is a 
 question of the attention, /. e., that it is an intellectual arousal 
 that causes the results described in this paper. That there is an 
 arousal of the whole person is certain ; but whether the 
 heightened maxima, as in the case just cited, are due to the 
 attention directly or to an indirect effect of the general stir, it 
 is difficult to be certain. I do not feel that it is a question of 
 the will primarily, for that factor is supposed to be eliminated 
 from the experiment by the instruction at the commencement 
 of work, when the subject was told to make his maximum 
 effort each time. 
 
 Yet with these misgivings, it seems natural to explain the 
 greater efficacy of the auto-suggestions by a greater concentra- 
 tion of the attention upon the work in hand. An auto-sugges- 
 tion consisted of the statement by the conductor of the experi- 
 ment, "Now you can make a suggestion of your own "; this 
 was followed by the statement of the subject, " Now I can make 
 it stronger than usual" or " Now I can't make it as strong as 
 
EFFECT OF SUGGESTION UPON MUSCULAR ACTIVITY. 293 
 
 usual." The whole process tended to call forth greater con- 
 centration of attention to the next grip of the dynamometer than 
 would result from either the auditory or visual suggestion, where 
 there was only an act on the part of the conductor. 
 
 On the other hand a certain broad arousal perhaps accounts 
 for the marked superiority of the motto suggestions, "Now 
 you can make it stronger than usual " and " Now you can't 
 make it as strong as usual " over the symbol suggestions, ' + ' 
 and ' — .' The latter, especially when spoken ('auditory sug- 
 gestion ') occupied but a moment and did not arouse the subject 
 as did the motto-suggestions, for the latter required a greater 
 length of time to be understood. 
 
 Introspections of all three subjects were in general that the 
 suggestions had little effect upon them. For example at the 
 end of the second term subject ' B ' once stated that the auditory 
 suggestion ' can ' seemed perhaps most powerful and the visual 
 suggestion ( + ) was next, but that it did not seem as if any 
 were strong enough to produce an effect. And about the same 
 time subject 'J' stated her feeling as follows, " When I stop to 
 think the suggestion seems to have little effect, but when not 
 thinking I feel that I obey the suggestion." Throughout the 
 experiment notes were taken of those cases in which the subject 
 expressed himself as satisfied or dissatisfied with the result. A 
 careful analysis of these fails to show any correlation between 
 the actual result and the introspections. 
 
 lli)teit| of Caiifofnia 
 
 Psychological laboratoi). 
 
[Reprinted from The Psychological Review, Vol. XVII., No. 4, July, 1910.] 
 
 XIII. The Localization of Diasclerotic Light. 
 
 BY G. M. STRATTON. 
 
 Sometime agoVeraguth^ announced that the sensation pro- 
 duced by stimulating the retina through the sclerotic coat instead 
 of through the pupil is often localized upon the same side as 
 that upon which the stimulus falls, and that this is particularly 
 true when the stimulus falls upon the temporal side. With 
 some persons, however, he found that under these circumstances 
 there was, in addition to the sensation on the temporal side, a 
 weaker sensation localized upon the nasal side. On the other 
 hand, when the stimulus was applied to the nasal side the sensa- 
 tion was always localized in the normal way, that is, it was 
 referred to the temporal side. When the light was applied to 
 the sclerotic, not in a radial, or diametric, direction, but in a 
 direction approximating that of the tangent at that point, no 
 change was noticed in the place the light seemed to occupy in 
 the visual field. From this fact Veraguth argues against the 
 assumption that the light, when it falls upon the temporal side 
 of the sclerotic, passes through and strikes the retina upon the 
 nasal side and therefore is referred in quite normal fashion to 
 the side opposite to that upon which it really affects the retina. 
 He believes that we have here an indubitable departure from 
 the common cross-localization of visual impressions, and would 
 explain this departure by the biological principle of utility. As 
 regards the need of a correct localization of light penetrating 
 the sclerotic, there is, he feels, a great difference between the 
 temporal side of the eye which is open and exposed, and the 
 inner or nasal side which is screened by the nose. And he 
 maintains that the correct orientation of light coming diasclerot- 
 ically is important only when the light falls on the temporal 
 side ; on the nasal side the light would come not only through 
 the sclerotic coat, but through the pupil, and therefore would 
 
 ^ ' Die Verlegung diaskleral in das menschliche Auge einfallender Licht- 
 reize in den Raum,' Zeitschrift fur Psychologic, Vol. 42, pp. 162 fif. 
 294 
 
 Onlwfsitj of California 
 
 pi iBboratory. 
 
295 G. M. STRATTON. 
 
 be localized correctly according to the well-known law. Pres- 
 sure phosphenes, unlike many of these sensations produced by 
 diasclerotic stimulation, are all projected, he finds, to the oppo- 
 site side of the visual field ; and this to him seems reasonable, 
 because there is no advantage in their being projected other- 
 wise. They therefore follow the general law for the projection 
 of a stimulus which comes through the pupil. 
 
 Veraguth believes that the present phenomena are a stum- 
 bling block in the way of the nativistic theory of vision which 
 supposes that the space value of the impression inheres in the 
 retinal element. For, if this were the case, why should there 
 be a difference between the localization of the sensation re- 
 sulting from the diasclerotic stimulation and that from the dia- 
 pupillary? But the empiristic theory, he argues, can well 
 admit and explain these diverse facts, for it supposes that 
 localization is due to a complex of factors, of which the retinal 
 factor is but one. Now the diasclerotic and the diapupillary 
 stimulation, he holds, may each arouse a different group of 
 factors to determine its localization. Each may well be con- 
 nected, for example, with a different group of muscular re- 
 sponses, and therefore, according to the empiristic view, have 
 a different localization. With some persons it is not improbable 
 that both the complex of factors concerned in diasclerotic locali- 
 zation and the complex concerned in diapupillary localization 
 may come into play simultaneously, and thus there be brought 
 to pass by diasclerotic stimulation a localization at once on both 
 sides of the visual field. Thus he would explain the double 
 projection which was sometimes noticed in his experiments. 
 
 To control Veraguth's data and explanation a number of ex- 
 periments were tried by the present writer, at first by means of a 
 very strong beam of artificial light in a dark-room and brought to 
 a point on the sclerotic coat by means of a system of screens and 
 lenses. Afterwards, a device essentially the same as that em- 
 ployed by Veraguth himself^ was adopted. It consisted of a 
 portable flash-light so covered at the end that the light was emit- 
 ted only from a circular area less than one millimeter in diameter. 
 
 ^Veraguth, " Zur Priifung der lyichtreaction der Pupillen,' Neurologisches 
 Centmlblatt (16 April, 1905), XXIV. Jahrg., 33Si:f. 
 
LOCALIZATION OF DIASCLEROTIC LIGHT. 296 
 
 This small opening lying well forward and beyond the body of 
 the lamp could be brought close to the sclerotic coat of the eye, 
 yet without actual contact. In this way the disturbing sensations, 
 as well as the reflexes so difficult to suppress, were avoided. 
 The observations were made by four persons ; by two of these 
 during frequent repetitions of the experiment over a consider- 
 able stretch of time. In general, these experiments while con- 
 firming much that Veraguth himself reports, yet bring some 
 modification and supplement of his data, and lead, I venture to 
 suggest, to a different conclusion. 
 
 There are regions upon the temporal side where the light is 
 lo'calized in the normal way ; that is, upon the nasal side. 
 There are regions where the light is localized entirely upon the 
 temporal side. There is often found also a zone where there is 
 some kind of localization upon both sides at once. The relation 
 of these zones to one another is as follows : The region where 
 the sensations are localized on the same side begins immediately 
 posterior to the outer edge of the iris and extends backward 
 a distance nearly equal to the distance from the center of the 
 pupil to the outer edge of the iris. The region where the lo- 
 calization is upon the opposite side is still farther back. The 
 region of double localization lies at the junction, or between the 
 borders, of these two zones. 
 
 Upon the nasal side of the eye my own observations confirm, 
 but not entirely, those of Veraguth. The localization is now 
 far more frequently upon the side opposite to that upon which 
 the stimulus falls, than in the case of temporal stimulation 
 through the sclerotic coat. Yet occasionally there are found 
 localities well forward where the sensation is localized upon the 
 same side as the stimulus. 
 
 The localization of pressure phosphenes shows this pecu- 
 liarity : that the phosphenes, so far as I can observe, are obtain- 
 able only upon those regions of the eye where light stimulus, 
 passing through the sclerotic coat, arouses what I should call a 
 more definite, a more figurate or punctiform sensation. In the 
 anterior region where the application of light upon the sclerotic 
 gives a vague sensation of light, local pressure upon the scle- 
 rotic coat produces no phosphenes whatever. The phosphenes. 
 
297 G. M. STRATTON. 
 
 however, when produced, are always localized upon the side 
 opposite to that of the incidence of the stimulus, as Veraguth 
 himself observed. By test experiments in which there was 
 carefully noted the angle in the visual field where the extreme 
 outlying phosphenes are localized, I find them ceasing to appear 
 at about the outmost limit for the perception of light coming 
 through the pupil. This would tend to confirm one in the be- 
 lief that the retinal limit for response to actual light is the same 
 as that for pressure stimulation. 
 
 Veraguth has laid considerable emphasis upon the fact that 
 no change in the localization of the sensation takes place when, 
 instead of having the stimulus come to the outer coat of the eye 
 in a diametric direction, it is introduced in a direction approxi- 
 mately that of the tangent at that point. It does not seem, how- 
 ever, that this fact should be regarded as of great importance. 
 It would be of importance were the outer coats of the eye 
 perfectly transparent ; but the sclerotic, being translucent, 
 would in any event diffuse the light much as would tissue-paper 
 or egg-shell ; that is to say, the light would be transmitted in 
 all directions from the point of incidence more or less indiffer- 
 ently, whether the light itself, in arriving at that point, came in 
 one direction or another. In consequence, we should expect 
 that if the sensation itself were in anywise due to the passage 
 of light into the bulb of the eye, and over to the retina upon the 
 opposite side, it would not be affected by a change from dia- 
 metric to tangential incidence. 
 
 Another fact which must be taken into account in the ex- 
 planation of the experimental data is that there is a retinal zone 
 of considerable width anterior to the 07'a scrrata which contains 
 neither rods nor cones. ^ Yet this is a region where light, falling 
 upon the sclerotic coat, nevertheless produces light sensations. 
 And, furthermore, the present experiments lead me to believe that 
 this is the region especially liable to the production of the dif- 
 fused sensations which are localized upon the temporal side, 
 both by temporal and by nasal stimulation. It would seem, to 
 
 ^See Piersol, Human Anatomy, 1907, pp. 1456, 1467 ; Tolot, Anatomischer 
 Atlas, 1907, p. 892 ; Werner Spalteholtz, Hand Atlas of Human Afiatomy, tr. 
 Barker, III., 772, 780; Huber, Text-book of Histology, tr. Gushing, 1900, p. 
 422. I am indebted to my colleague, Dr. Moody, for assistance upoq,this point. 
 
LOCALIZATION OF DIASCLEROTIC LIGHT. 298 
 
 express it mildly, anomalous to explain the localization of light 
 here as though there were actual light-sensitive elements 
 directly beneath the region of the sclerotic where the stimulus 
 falls. 
 
 There is, one must confess, some difficulty at the present 
 time in giving any explanation of all the facts which appear in 
 this interesting experiment. Yet on the whole there would 
 seem sufficient reason to believe that Veraguth's theory is forced 
 and improbable. 
 
 In the first place, it is hardly in keeping with other well- 
 known facts of retinal behavior to suppose that the stimulation 
 of the very same retinal elements will lead to such different 
 localization by reason of some change in the manner of 
 a^p'oach to those elements. The stimulation of the rods and 
 cones by pressure, for example, — a stimulation which also 
 comes through the sclerotic, and consequently by a course 
 entirely different from that of ordinary photic stimulation — 
 occasions no upset of the normal localization of these elements ; 
 their sensation is referred to exactly the same place as though 
 it were caused by light, and had come through the pupil. 
 
 The facts perhaps are better explained by assuming that the 
 light which penetrates the sclerotic coat posterior to the ora ser- 
 rata and which consequently excites the light-sensitive elements 
 of the retina directly beneath or adjacent produces the definite or 
 figurate sensation which is localized upon the opposite side. 
 This is the region where the localization of phosphenes and that 
 of sensations produced by light stimulus are identical. But 
 where the light falls anterior to the ora serrata it of course can- 
 not reach immediately and upon the same side of the eye light- 
 sensitive elements but can stimulate them only after first being 
 diffused through the interior of the bulb. The character of 
 this diffusion will be such that the light will pass in straight 
 lines from its point of incidence upon the sclerotic, but in lines 
 traversing the interior of the bulb in all directions and not 
 just in the direction which is a continuation of that along which 
 it was travelling before its incidence. The behavior of the 
 light here is such as one would get in a dark room if a beam of 
 light fell upon a plate of ground-glass in an aperture of the 
 
299 ^- ^^- STRATTON. 
 
 wall. There would be a general illumination of the room but 
 naturally more intense upon the side opposite to the illuminated 
 spot, yet diffused and unfigurate upon that side. 
 
 This would account for two facts : namely, that the sensa- 
 tion in the case of such light stimulation as falls very far forward 
 on the sclerotic is exceedingly indefinite, and is localized upon 
 the same side as that upon which the light itself has been intro- 
 duced into the eye. Furthermore, it would account for the 
 fact, already referred. to, that a change in the direction along 
 which the light falls upon the sclerotic does not alter the char- 
 acter of the projection, provided the point of incidence remain 
 unchanged. The position of greatest illumination in our dark- 
 room would not be altered perceptibly by altering the direction 
 along which the light proceeded to the plate of ground-glass. 
 
 The behavior of the sensation produced by light falling on 
 the nasal side one must confess is mildly puzzling. For the 
 most part all stimuli here, no matter how far forward they fall, 
 are referred to the opposite side ; yet we should expect that if 
 we go forward of the ora serraia on this side we should find 
 that the sensations were referred exclusively to the nasal side. 
 The facts here obtained may perhaps be accounted for by the 
 fact that the ora serrata upon this side reaches farther forward ^ 
 than upon the opposite side, in accord with the familiar obser- 
 vation that the field of view upon the temporal side is always 
 wider than upon the nasal. Consequently the stimulus intro- 
 duced diasclerotically upon the nasal side would almost inevi- 
 tably find light-sensitive elements adjacent to, if not directly 
 beneath, the point of incidence; and the sensation thereby pro- 
 duced would by its intensity quite drown any sensation arising from 
 a diffusion inside the eye. It is possible also that this phenome- 
 non of irregular localization is to some extent occasioned by a 
 reflection of light from the surface of the crystalline lens per- 
 haps near its periphery. This surface of the lens might easily 
 reflect the light back to the same side as that upon which it 
 entered the sclerotic, though to a point somewhat farther back. 
 Thus it would reach the sensitive portions of the retina and now 
 quite normally be localized upon the opposite side. 
 
 ^See, e. g., Werner Spalteholtz, op. cit., III., p. 780. 
 
LOCALIZATION OF DIASCLEROTIC LIGHT. 300 
 
 All cases where there is a double localization from a single 
 stimulation, that is to say, a localization at once upon both 
 sides of the visual field, could well be accounted for by sup- 
 posing that the light, after passing through the sclerotic, reaches 
 not solely those light-sensitive elements which lie in the portions 
 of the retina immediately beneath or adjacent, but is also dif- 
 fused to the opposite side of the inner chamber and there falling 
 diffusely upon the retina is referred to the side opposite to that 
 upon which the more definite sensation is localized. We should 
 thus have two spacially disjoined sensations occurring from a 
 single impression because the stimulus actually fell upon dis- 
 joined portions of the retina. 
 
 My own feeling therefore is that nothing appears in these 
 experiments with diasclerotic light which is at all discordant 
 with the law governing the localization of diapupillary impres- 
 sions. Visual localization is based upon the positions which 
 objects normally occupy when stimulating the different points 
 of the retina; and this localization, once established, takes 
 no account whatever of the course by which the stimulus 
 happens actually to arrive. No questions are asked as to 
 whether it has entered by the door or has broken in as a thief 
 and a robber; it is treated in all cases psychically alike. 
 
 llnlYcrsltf of California 
 
 Psychological Laboratory. 
 
FROM THE UNIVERSITY OF CALIFORNIA 
 PSYCHOLOGICAL LABORATORY 
 
 XIV. The Psychology of Change: on Some Phases 
 OF Minimal Time by Sight 
 
 BY JOHN M. BREWER, B.S. 
 
 Repiinted from the Psychoi^ogicai, Review, July, 191 1, 
 Vol. XVIII, No. 4. 
 
 ""'tfsffy «f California 
 

 [Reprinted from The Psychological Review, Vol. XVIII., No. 4, July, 1911.] 
 
 FROM THE UNIVERSITY OF CALIFORNIA 
 PSYCHOLOGICAL LABORATORY 
 
 XIV. The Psychology of Change: on Some Phases 
 OF Minimal Time by Sight 
 
 BY JOHN M. BREWER, B.S. 
 
 The present paper is concerned with the description of an 
 experiment that attempts to bring nearer the answer to the 
 following questions: (i) What is the smallest time-interval 
 between two successive lights when the lights are seen to 
 come not simultaneously but in succession? (2) What is 
 the smallest extent of time that a motion can last, and still 
 be perceived as motion? And the investigation of these two 
 questions, with the hope of bringing out some connection or 
 disconnection of the one group of facts with the other, was 
 confined to a special set of conditions; namely, that in which 
 the two points whose succession or simultaneity Is to be 
 observed, are not in absolute juxtaposition but are appreciably 
 apart, and where the space-interval between them Is varied 
 as we pass from group to group of experiments. For It 
 seemed an open question whether an advantage that might 
 accrue, let us say, to either motion or succession, when one 
 space-interval was involved, would also be maintained with 
 a different Interval of space. 
 
 The subject, in a somewhat darkened room, was placed 
 360 cm. distant from a large screen bearing a narrow vertical 
 slit that could, for the sake of proper fixation, be dimly seen. 
 And In this position he saw either two lights in succession, 
 one directly above the other, or else a moving point of light. 
 These were produced In the following way. Behind the 
 screen and directly in line with the slit was a surface evenly 
 lighted by an electric light; and between screen and lighted 
 surface swung a pendulum, bearing a wide sheet of metal, 
 set Into w^hlch were devices for producing the appearances 
 
 257 
 
25S JOHN M. BREWER 
 
 described above. For giving an appearance of succession 
 two small apertures were cut in separate slides that were in 
 reality circular arcs so arranged that the apertures would 
 pass the slit with a varying intervening time, yet with no 
 varying of their distance from the point of suspension of the 
 pendulum; and consequently for any given set of experiments 
 they presented to the observer always the same angular, or 
 vertical, separation. Yet in the different sets of experiments 
 the amount of their vertical separation differed, being respec- 
 tively 7, 10 and 19.5 mm., or, expressed in angular measure, 
 6.7', 9.5' and 18.6' of arc. 
 
 Instead of the appearance of succession, it was possible 
 to offer an appearance of motion by substituting for the 
 apertures just described a circular card that could be moved 
 at will about its own center. In this circular card there was 
 a narrow slit; and by different settings of the card its slit 
 could be placed at any angle to the slit in the stationary 
 screen immediately before it; and consequently there was 
 presented to the observer the appearance of a point of light 
 moving either up or down. The extent of the motion up 
 and down was carefully limited by opaque surfaces above 
 and below, and made to correspond, in the three parts of the 
 experiment, with the spatial angles above mentioned: 6.7', 
 9.5' and 18.6'. The velocity of the apparent movement, 
 of course, varied step by step with the shifts in the angle of 
 the pendulum slit. The swing of the pendulum was kept 
 constant by the use of magnets, and its speed in the vicinity 
 of the center was carefully calibrated by means of a tuning- 
 fork. 
 
 In determining the thresholds for the different orders of 
 stimulation, the method of serial groups^ was used, 'no- 
 interval' cases being intermixed about equally with the inter- 
 vals whose thresholds were sought. The threshold was 
 crossed after the manner of the method of minimal changes, 
 and for both orders of sequence (viz., upper light first, and 
 lower light first), and of motion (viz., downward and upward). 
 Each value in Tables I.-III. is then an average of four 
 
 1 See ' Studies from the Univ. of Calif. Lab., IV.,' Psychol. Review, IX., 1902, 444. 
 
MINIMAL TIME BY SIGHT 
 
 259 
 
 'determinations' and into each determination there enter 
 forty to fifty experiments. And since it was often the case 
 that an observer could tell that the lights came at different 
 times, but could not tell which came first, or observed motion, 
 though he could not tell its direction, the two kinds of 
 threshold are here recorded separately — the threshold for the 
 
 Table I 
 
 Thresholds, Expressed in ff, for Visual Angle 6.7' 
 
 
 With Discrete Sequence. 
 
 with Motion. 
 
 Observer. 
 
 Judg. of Succes- 
 sion Merely. 
 
 Judg. of Order of 
 Succession. 
 
 Judg. of Motion 
 Merely. 
 
 Judg. of Direction 
 of Motion. 
 
 B 
 
 L 
 
 M 
 
 S 
 
 W 
 
 22 
 22 
 
 54 
 
 20 
 
 33 
 
 29 
 22 
 60 
 
 22 
 
 43 
 
 29 
 21 
 48 
 30 
 
 22 
 
 31 
 21 
 48 
 32 
 30 
 
 Table II 
 
 Thresholds, Expressed in <r, for Visual Angle 9.5' 
 
 
 With Discrete Sequence. 
 
 With Motion. 
 
 Observer. 
 
 Judg. of Succes- 
 sion Merely. 
 
 Judg. of Order of 
 Succession 
 
 Judg. of Motion 
 Merely. 
 
 Judg. of Direction 
 of Motion. 
 
 B 
 
 L 
 
 M 
 
 S 
 
 W 
 
 22 
 32 
 58 
 
 35 
 33 
 
 30 
 32 
 61 
 
 35 
 33 
 
 22 
 
 33 
 28 
 21 
 
 22 
 19 
 
 33 
 32 
 21 
 
 Table III 
 
 
 Thresholds, Expressed in c, for 
 
 Visual Angle 18.6' 
 
 
 With Discrete Sequence. 
 
 With Motion. 
 
 Observer. 
 
 Judg. of Succes- 
 sion Merely. 
 
 Judg. of Order of 
 Succession. 
 
 Judg. of Motion 
 Merely. 
 
 Judg. of Direction 
 of Motion. 
 
 B 
 L 
 
 M 
 
 S 
 
 W 
 
 37 
 28 
 
 S3 
 
 45 
 43 
 
 39 
 30 
 60 
 
 45 
 52 
 
 30 
 20 
 76 
 24 
 20 
 
 30 
 20 
 76 
 
 24 
 20 
 
 bare perception of the succession or motion, and that for the 
 definite order of the succession or for the direction of motion. 
 It should be said that the subjective appearance of motion, 
 which Exner noticed, did not appear to any important 
 
36o 
 
 JOHN M. BREJVER 
 
 extent in making these determinations. Only one subject 
 had this illusion, and he for a very short time only. The 
 results are stated in thousandths of a second. 
 
 There is in many cases, as these tables show, a lower 
 threshold when motion is offered than when there is offered 
 discrete sequence. In the thirty pairs of values that are 
 comparable in this respect, twenty-one show a clear advantage 
 for motion. Yet in none of these pairs is there any such 
 advantage as Exner noted. Moreover, it is evident that the 
 smallest visual angle is for the greater number of the observers 
 the most favorable of the three for the perception of the 
 discrete sequence, whether the judgment passed be of sequence 
 merely or be of the order of the sequence. The separation 
 of the lights would here seem to be sufficient to prevent at 
 least any troublesome degree of overlapping of the irradiation 
 circles upon the retina, and at the same time not so great as 
 to render comparison difficult. At the angle 9.5', such com- 
 parison seems already to have become harder and at 18.6' 
 harder still. For the perception of motion, however, the 
 most favorable space extent for most of the observers was 
 neither the shortest nor yet the longest of the three employed, 
 but the middle distance. Motion through the angle 6.7' 
 seems to have been too short to be most readily seen as 
 motion; while with the angle 18.6' there evidently was again 
 some difficulty, though of a different kind and greater — that 
 again prevented the distance from being optimal. 
 
 Some idea of the comparative advantages of the different 
 angular extents may be gained from the following table where- 
 in the thresholds for the different orders of perception are 
 stated in the form of averages of the time obtained for all 
 five of the observers. 
 
 Table IV 
 
 Average Thresholds, Expressed in <t, for the Three Visual Angles 
 
 
 Visual Angle 6.7'. 
 
 Visual Angle 9.5'. 
 
 Visual Angle 18.6'. 
 
 Character of Change 
 Presented. 
 
 Judg. of 
 Occur- 
 rence 
 
 Merely. 
 
 Judg. of 
 Order or 
 Direction 
 of Occur- 
 rence. 
 
 Judg. of 
 Occur- 
 rence 
 Merely. 
 
 Judg. of 
 Order or 
 Direction 
 of Occur- 
 rence. 
 
 Judg. of 
 Occur- 
 rence 
 
 Merely. 
 
 Judg. of 
 Order or 
 Direction 
 of Occur- 
 recne. 
 
 Discrete sequence 
 Actual motion 
 
 30 
 30 
 
 35 
 
 32 
 
 36 
 
 25 
 
 38 
 26 
 
 41 
 
 34 
 
 45 
 34 
 
PERCEPTION OF MOVEMENT 261 
 
 So far as discrete sequence is concerned, there are, how- 
 ever, exceptional observers, like M, who reveal no great 
 difference as we pass from one visual angle to another; or, 
 like B and W, for whom 6.7' and 9.5' are practically alike, 
 while 18.6' shows a distinct disadvantage. And, again, in 
 the region of motion, the general advantage possessed by the 
 medium extent 9.5' practically disappears with the observer 
 W for whom there is, if anything, a very slight drop in the 
 thresholds as we pass out to the very largest angle, that of 
 18.6'; and with another observer, S, this same tendency is 
 even more clear, and the longest distance, 18.6', is now the 
 most favorable of all. Yet the departure of these observers 
 from the precise relations found with their fellows permits 
 one still to say that there is in general in shorter space-extents 
 a condition favorable to the perception of discrete sequence, 
 and yet unfavorable to the perception of motion. And while 
 the most favorable extent here used for perceiving discrete 
 sequence gives, on the average, a minimal threshold of 300-, 
 the most favorable extent for perceiving motion gives a 
 threshold of 250-; the threshold for the perception of discrete 
 sequence is thus about one fifth higher than that for 
 motion. This, however, shows that at least under the peculiar 
 conditions of the present experiment, there is a considerable 
 departure from the relation which Exner believed to exist, 
 namely, that the time-threshold for the perception of succes- 
 sion is about three times as high as that for the perception of 
 motion. 
 
 Unlwtilt^ of Califsrala 
 
FROM THE UNIVERSITY OF CALIFORNIA 
 PSYCHOLOGICAL LABORATORY 
 
 XV. THE PSYCHOLOGY OF CHANGE: HOW IS THE 
 
 PERCEPTION OF MOVEMENT RELATED TO 
 
 THAT OF SUCCESSION? 
 
 BY G. M. STRATTON 
 
 Repiinted from the Psychological Review, July, 1911, 
 Vol. XVIII, No. 4. 
 
 Mm^ t)^ California 
 
 PsyGtioiogiGal Laboratoi). 
 
XV. THE PSYCHOLOGY OF CHANGE: HOW IS THE 
 
 PERCEPTION OF MOVEMENT RELATED TO 
 
 THAT OF SUCCESSION? 
 
 BY G. M. STRATTON 
 
 Um^ nf ilellfofnia 
 
 Psycbologjcai Laboratory. 
 
[Reprinted from The Psychological Review, Vol. XVIII., No. 4, July, 191 i-l 
 
 XV. The Psychology of Change: How is the Perception 
 OF Movement Related to that of Succession? 
 
 BY G. M. STRATTON 
 
 The experiments to be described deal with a narrow 
 margin of that wide process by which we are conscious of 
 change. For even with all the interest that has in past 
 years been shown in this complex act, one can hardly 
 say that there is as yet any general agreement as to its inner 
 character or as to its outer connections. It has repeatedly 
 been asserted that change is, at its best, caught by us 
 directly and simply; that when we notice some sudden 
 brightening of a light or damping of a sound or increase of 
 pain or shift of place, the change-experience itself is of a 
 unique quality, like the taste of bitter or the sight of blue, 
 and that at such times the process has all the marks of a 
 sensation. The detection of change, it is held, involves at 
 such times no comparison, no overspanning consciousness 
 that now the object is in one state or condition and now in 
 another, but we become aware of the change in a single and 
 simple throb of mind. And all this has been denied. 
 
 In the case of visual movement, to be more specific — for 
 with visual movement alone the present experiments are con- 
 cerned — orthodox belief has been that there is always present 
 a double act of discrimination, at once of instants and of 
 positions; against which is the belief that the retina is directly 
 responsive to rapid movements of light, and that the move- 
 ment is perceived without any such complex dealing at once 
 with space and time. The idea of an absolutely direct and 
 simple sensory appreciation of motion suggested by Czermak^ 
 and to some extent furthered by Vierordt,- found a strong 
 
 1 'Ideen zu einer Lehre von Zeitsinn,' Sitzungsb. d. kaiserl. Akad. d. zviss. Math.- 
 Naturwiss. CI, Vol. 24 (Vienna, 1857), pp. 231-236. 
 
 2 'Der Zeitsinn nachVersuchen,' 1868; cf. especially pp. 114 f., where Vierordt says 
 that in perceiving motion both the time-sense and the space-sense are required, 
 but that the processes involving space and time cease to arise clearly in conscious- 
 ness because they run so smoothly and habit-like, and so the whole takes on a 
 quasi-sensory character. Accordingly, says he, we may as justly use the expression 
 Ceschwindigkehsempfindungen as Zeit- und Raumgrossenempfindungen. 
 263 
 
PERCEPTION OF MOVEMENT 263 
 
 supporter in Exner, whose argument rests upon two kinds 
 of experimental observation, in the region of space and of 
 time respectively. In regard to space, rapid motion can be 
 discerned, he held, within limits too narrow for space-dis- 
 crimination; a small disk of light can be seen to move even 
 when its excursion is considerably less than the distance be- 
 tween two such disks of light that, when stationary, already 
 appear as one. Consequently (we may paraphrase his argu- 
 ment) space-discrimination cannot he an essential part of the 
 process of perceiving motion^ at least when rapid. Further- 
 more, and now passing over into the region of time, motion 
 can be seen as motion even when its duration is far less than 
 the least time that permits us to notice succession. If instead 
 of making the excursion through a shorter and shorter dis- 
 tance, the extent of the excursion remain constant and the 
 movement be made more and more rapid, Exner found that, 
 even when the motion occupied a time so brief that two 
 sparks, the one at the beginning, the other at the end of such 
 duration, seemed absolutely simultaneous, the motion was 
 still perceptibly motion. Consequently (so runs the thought) 
 time-discrimination cannot be an essential part of the process 
 of perceiving motion.^ 
 
 As regards the first part of this argument — the part that 
 deals with space-discrimination — I may perhaps refer to 
 experimental evidence already offered by myself tending 
 strongly (so it seems to me) to show that the facts upon 
 which the argument is based were gathered far too narrowly.^ 
 If, instead of relying on the two-point method of determining 
 the space-threshold, we employ a method involving the ap- 
 parent dislocation or coincidence of two parallel lines placed 
 end to end, the power to detect differences of position is 
 approximately the same as that for the perception of move- 
 ment. And consequently a full half of the ground for believ- 
 ing in the psychic simplicity and independence of movement 
 caves away. 
 
 1 Cf. the argument as set forth in James's Principles of Psychology, II., 172. The 
 refs. to Exner are found below. 
 
 2 'Visible Motion and the Space-threshold,' Psychological Review, IX., 433 flF.; 
 and cf. Bourdon: La perception visuelle de Vespace, pp. 144 f., with the refs. there given. 
 
264 G. M. STRATTON 
 
 I. Previous Experimental Work 
 Exner's experiments upon the time-factor in the percep- 
 tion of visual movement were in substance as follows.^ Using 
 close-neighboring electric-sparks, he found that with eyes at 
 a certain distance from the sparks the most rapid succession 
 that could be discerned was one of 440-. But by more than 
 doubling the distance between eye and sparks and thus pro- 
 portionately diminishing the visual angle between the sparks 
 and at the same time producing an illusion of movement from 
 one to the other, he found this movement still noticeable 
 when the time-interval was shortened by practice to I5<r. 
 Substituting for the electric sparks flashes of light through 
 two apertures in a screen, Exner could tell correctly the order 
 of sequence when the flashes were 45a apart; but when the 
 portion of the screen between the two apertures was cut out 
 and otherwise so arranged as to give a moving light between 
 these two localities, motion could still be perceived when its 
 duration was but 140-. Motion, whether real or apparent, 
 thus had power, it seemed, to reduce the limit below which 
 a visual stretch of brightness appeared as a synchronous and 
 uniform illumination. Exner's data for this conclusion 
 were obtained from foveal vision; with eccentric vision he 
 found it impracticable to exclude the appearance of motion; 
 he was thus unable to compare in this region the times of 
 just-visible motion and of succession apart from movement. 
 Charpentier, who next in any significant way approached 
 the problem, employed a method much the same as the second 
 of Exner's described above, yet with this important difference, 
 — that instead of producing discrete succession by separated, 
 although neighboring spots of light, he arranged a vertical 
 slit, of which he could illuminate independently the upper 
 and the lower half, and thus the sensations whose sequence 
 or simultaneity was to be caught appeared in absolute juxta- 
 position. He found: (i) that if the time-interval between 
 the halves be slight, they seem illuminated simultaneously; 
 
 ^ Exner, 'Experimentelle Untersuchung der einfachster psychischen Processe 
 Pfliiger's Archiv, VII., 6oi ff.; VIII., 526 ff.; XL, 4035.; 'Ueber das Sehen von Be- 
 wegungen und die Theorie des zusammengesetzten Auges,' Sitzungsb. d. kaiserl. Akad, 
 d. Wissens. Math.-Naturw. CI, LXXIL, Ft. in (Vienna, 1875), pp. 156 ff. 
 
PERCEPTION OF MOVEMENT 265 
 
 (2) with increase of this interval the illuminations seem dis- 
 tinct in time, but it is impossible to say which comes first; 
 
 (3) only with still greater increase of the time-interval can 
 one say which is first; and (4) the absolute duration of the 
 illumination of each half seems not to affect this detection 
 of sequence. On the average (and apparently from but a few 
 experiments) he found a noticeable difference when the be- 
 ginnings of the lights differed by 270-.^ With regard to 
 Charpentier's discussion of the error we make in the apprecia- 
 tion of succession — the illusion that successive lights are 
 simultaneous — it was contended by Bloch that this error 
 entirely disappears if the successive s'timulations do not fall 
 upon identical parts of the retina,^ — a surprising criticism, 
 apparently based neither on any right understanding of 
 Charpentier nor upon any reliable experiment of Bloch's own. 
 Charpentier, in reply ,^ after clearing up the matter of method, 
 says briefly and with restraint, that while he cannot deny 
 that the succession may continue to appear to the very end, 
 he is quite unable to notice it himself. Neither Charpentier 
 nor Bloch seem to have made more than a few trials nor to 
 have concerned themselves with obtaining comparable data 
 in the region of movement, and so of clearing up the problem 
 more directly before us. 
 
 This problem was, however, held distinctly in mind by 
 Stern,^ who arrives at a conclusion opposed to that of Exner. 
 But since his own experimental contribution is confined to 
 the spatial rather than to the temporal side of the question,^ 
 it hardly need here be reproduced. 
 
 1 Charpentier, 'Sur I'appreciation du temps par la retine,' Seance et Memoires de 
 la Societe de Biologie, Vol. IV., 8th Series (Paris, 1887), pp. 360-1; 'Nouvelle note sur 
 i'appreciation du temps par la retine,' ibid., pp. 373-5. 
 
 ^ Bloch, 'Note sur les sensations visuelles,' ibid., pp. 391-3. 
 
 3 Charpentier, 'Note sur le synchronisme apparent,' etc., ibid., pp. 447-8. 
 
 4 'Die Wahrnehmung von Bewegungen vermittelst des Auges,' Zeitschrift fur 
 Psychologie, etc., VII. (1894), 321 ff. Stern is in the neighborhood of the time-side of 
 the problem only when he considers the most favorable rhythm of motion if the motion 
 is to be noticed. Cf. my own discussion and opposing results, in 'Visible Motion and 
 the Space Threshold,' Psychological Review, IX., 433 ff. 
 
 'This is true also of the work of Basler, 'Ueber das Sehen von Bewegungen,' 
 Pfliiger's Archiv, 1906, XV., 582, 1908; CXXIV., 313. 
 
266 G. M. STRATTON 
 
 Weyer, experimenting with successive electric sparks, 
 given (it would seem) from a single sparker and consequently 
 appearing at one identical point, brought out some interesting 
 facts concerning the detection of sequence; but his interest 
 was not directly in our problem, and he made no attempt to 
 obtain in the field of movement data with which his results 
 upon succession might be compared. He found, however, 
 that in starting with so brief an interval that the two sparks 
 appeared as one, there were certain definite intermediate 
 stages before this appearance of precise singleness of spark 
 yielded to a clear appearance of succession. The apparently 
 unitary illumination began to drag, or 'persist' when the 
 interval was somewhat increased — to about i2o-, with day- 
 light adaptation. With still greater increase — to an interval 
 of 25(7-300- — there came a slight flicker. Finally, when the 
 interval was increased to 43o'-53cr, the two sparks appeared 
 in clear succession.^ 
 
 With Bourdon there was distinct interest in our particular 
 problem, and he accordingly gathered data both of succession 
 and of movement. He used small areas of white paper at- 
 tached to a revolving drum, so arranged that they produced 
 an appearance now of motion and now of mere sequence of 
 neighboring lights. When the conditions were on the whole 
 most favorable, he found motion recognizable by direct vision 
 at a duration of 270-. With discrete succession instead of 
 motion, he found it impossible to pass judgment when the 
 interval was only i6o-; his right judgments exceeded the 
 wrong when the interval was 200-; when the interval was 
 increased to 480-, he recognized with certainty the order in 
 which the lights disappeared. His conclusion is that the 
 perception of motion has no such preeminence over that of 
 succession as Exner claimed; indeed, the thresholds of these 
 two kinds of perception come to nearly the same measure.^ 
 
 ^ Weyer, ' Zeitschwellen gleichartiger und disparater Sinneseindriicke,' Wundt's 
 Philosop'kische Studien, XIV., 616; XV., 67. 
 
 ' Bourdon, La perception visuelle de Vespace, pp. 187 ff. Marbe {Theorie der kine- 
 matographischen Projectionen, 1910, p. 62) has added still later experiments, but again 
 upon but one of the two sides important for the present question. He finds that when 
 a series of 13 miniature incandescent lights flash in succession at a rate wherein the in- 
 terval between the flashes of adjacent lights is reduced to iiff the impression of move- 
 ment ceases. 
 
PERCEPTION OF MOVEMENT 267 
 
 Only Exner and Bourdon, then, maintained in the two 
 regions that must of necessity here be compared, a single 
 unchanging method applied under inner and outer conditions 
 that also in the main remained unchanged. And their 
 excellent work, I have ventured to think, still leaves room, 
 even apart from a certain conflict of outcome, for some doubt 
 and Inquiry. With Bourdon, for instance, it is clear that 
 exactly the same conditions were not maintained both in his 
 experiments upon succession and in those upon motion. The 
 lines that passed the slit were not alike in the two cases; and 
 this might have affected the apparent intensity of the sensa- 
 tions; the slit through which the stimulus appeared was, in 
 the case of the motion, horizontal and I mm, wide, in the case 
 of succession it was vertical and 0.4 mm. wide; the distance 
 between the observer and the lights was different In the two 
 cases. All these discrepancies should be removed, and the 
 two series to be compared should run on abreast to avoid any 
 possible advantage from the difference of training and prac- 
 tice. In particular It has seemed to me desirable to regard 
 as an open question what the eifect of certain variations of 
 method would be; and farther, just what space relation should 
 subsist between the successive lights, if the conditions were 
 to be most favorable for the detection of succession. Will 
 succession best be observed when the successive spots of light 
 are closer together or farther apart; when they are In juxta- 
 position or when some distance Intervenes.'' We should dis- 
 cover the most favorable conditions for each class of observa- 
 tions before we could finally decide as to their relative 
 superiority. 
 
 It would be idle to claim that the programme finally 
 adopted covers the ground; all that should be said Is that it 
 aims to clear up an obscure point or two. A part of It has 
 been carried out by an able student of mine, Mr. Brewer, — 
 the part dealing with successions that are not only temporally 
 but spatially separate. And his report accompanies and may 
 be regarded as an Intimate part of this discussion.^ His 
 experiments had shown a regular reduction of the time- 
 
 ' Brewer, The Psychology oj Change: On some Phases of Minimal Time by Sight, 
 in the present number of the Psychological Review. 
 
268 G. M. STRATTON 
 
 threshold for succession, as the visual angle was reduced. For 
 myself, I felt tempted to push this reduction to its very limit 
 by making trial, in the region of time, of a slight modification 
 of method that has proved of marked effect in studying 
 movement upon its spatial side. For it will perhaps be 
 remembered by some that a change in the manner of testing 
 the space-threshold, whereby lines were placed end to end, 
 instead of side by side, had reduced the space-threshold at 
 least five-fold and perhaps ten-fold; had reduced it from a 
 visual angle of 30" with stars, or of 60" if we keep to lines, to a 
 visual angle of approximately j" .^ Here in placing the 
 lines end to end, there is perfect proximity of the impressions 
 to be compared, yet without the easy fusion which befalls 
 lines side by side. An analogous procedure in the realm of 
 time would be to have the succession of flashes come, not 
 upon the same points of the retina where persistence of 
 impression would conceal the time-interval, but upon adja- 
 cent points, yet neither with confusion by overlapping cir- 
 cles of irradiation nor with any insistent illusion of movement. 
 This seemed attainable by means of a narrow slit, half of 
 which should be lighted at one instant, and half at another, — 
 the time-interval between these illuminations to be variable 
 and definitely known. The plan, then, involved the method 
 already employed briefly by Charpentier, and at the same time 
 the gathering of exactly comparable data regarding movement. 
 
 II, Experiments with Pendulum Device 
 In the present experiments two different arrangements of 
 apparatus were employed. The first group of experiments 
 was with the pendulum described in Brewer's paper already 
 mentioned;^ but with attachments other than those he used. 
 Imagine a plate of aluminum just above the pendulum's bob, 
 lying in the plane of oscillation. In this plate and at about a 
 distance of i m. from the point of suspension of the pendu- 
 lum there was a vertical radial slit 5 cm. long, with a mean 
 
 1 'A New Determination of the Minimum Visibile,' Psychological Review, VII., 
 249; 'Visible Motion and the Space-Threshold,' Psychological Review, IX., 433 ff. 
 Cf. Bourdon, La perception visuelle de Vespace, pp. 144 ff. 
 
 2 See pp. 25 f. 
 
PERCEPTION OF MOVEMENT 26^ 
 
 width of 4.5 mm. later narrowed to i mm. The pendulum 
 with this radial slit swung behind a stationary screen which 
 also had a vertical slit with parallel sides 2 mm. apart and 
 long enough to expose the full length of the slit behind. 
 Back of both screen and pendulum was ground glass evenly 
 illuminated by six i6-c.p. incandescent lamps. With certain 
 adjustments the observer, at a distance of 2 m., perceived a 
 momentary illumination of the vertical slit in the stationary 
 screen; while with other adjustments the upper and lower 
 half of the radial slit in the pendulum could be mutually so 
 displaced as to present to the observer the two halves of the 
 slit illuminated in quick succession. The exact point in. 
 the front slit where these two halves had their common 
 border was, for the sake of preparatory fixation, indicated 
 by white horizontal arrows, while the time-interval between 
 the illumination of the two halves could be exactly controlled 
 by a scale obtained chronographically. 
 
 The impression of movement, for the companion experi- 
 ments, was obtained by another attachment essentially the 
 same as that described in Brewer's paper.^ It need hardly 
 be said that here the same width of slits and intensity of 
 illumination of background, was maintained as in the experi- 
 ments on succession, and the extent of the motion was 
 identical with the length of the two illuminated halves then 
 used.^ And in all cases the two sets of experiments were so 
 arranged as to exclude any difference of practice or fatigue 
 in the two groups. There were two observers In the present 
 group of experiments, as well as in a second group later 
 to be described. To Dr. Brown, who gave unstintlngly of 
 time and good will In these none-too-interesting tests, I 
 acknowledge my great indebtedness. 
 
 Since the tendency here is to see every impression as 
 motion and indeed as motion in some particular direction, 
 
 iSee p. 258. 
 
 2 Brewer's experiments, It will be seen, showed that the optimal excursion for 
 perceiving motion is, unlike that of succession, by no means near zero. With some 
 it seems to lie at least as far out as a visual angle of 18.6'. The motion in the present 
 experiments was some five times this extent, and in all probability included the optimal 
 excursion for my observers. 
 
270 
 
 G. M. STRATTON 
 
 the 'method of serial groups'^ was used Instead of the more 
 common gradation method. The procedure was ' unzvissent- 
 lich\' and but a single movement, or pair of lights in succes- 
 sion, was oflfered for judgment. At first an attempt was made 
 to distinguish, in each judgment, not only between motion 
 and succession but also between the two orders of succession 
 (upper first; lower first) and the two directions of movement 
 (down; up). But prepossession soon proved too strong, and 
 so wide a range of intervals was needed to catch all phases of 
 these judgments that I finally abandoned the attempt to 
 obtain thresholds for the correct perception of the order of 
 
 Table I 
 
 Observer B 
 
 Thresholds expressed in mm. (l mm. = JT.Jff) 
 
 Order of Presentation 
 
 With Two Successive lyights 
 
 With Moving I,ight 
 
 Above-below 
 
 Below-above 
 
 Downward 
 
 Upward 
 
 With wider slit. 
 
 12 
 II 
 
 18 
 15 
 
 17 
 17 
 IS 
 15 
 
 35 + 
 
 35 
 
 45 
 
 25 
 30 
 
 25 
 
 Average. 
 
 14 
 
 16 
 
 38.3 
 
 26.7 
 
 With narrower slit. 
 
 15 
 20 
 
 20 
 
 22 
 
 40 
 35 
 
 25 
 20 
 
 Average. 
 
 17-5 
 
 21 
 
 37-5 
 
 22.5 
 
 Combined average. 
 
 15.2 
 
 17.7 
 
 38 
 
 25 
 
 Average for the two orders 
 of presentation. 
 
 16.4 
 
 31-5 
 
 succession and for the direction of motion, which are un- 
 questionably distinct from the thresholds for the perception 
 of mere succession and mere motion. I felt content to note 
 the point at which actual succession on the one hand and 
 motion on the other, no longer seemed sheer simultaneity of 
 Illumination. Yet the observers were, through a large part 
 of the present group of experiments, more or less concerned 
 to make out more exactly the nature of whatever departure 
 from simultaneity they noticed, and so their judgments were 
 not quite untrammelled and homogeneous. Yet they should 
 perhaps be entered, since in several ways they are worth 
 
 'See Psychological Review, IX., 444 ff. 
 
PERCEPTION OF MOVEMENT 
 
 271 
 
 comparing with the group to be spoken of some pages hence. 
 Each 'determination' given in the tables accompanying 
 (Tables I. and 11.) represents never less than 50 nor more 
 than 100 separate judgments. In all, there were between 
 1,500 and 1,600 judgments in this group, apart from many 
 preliminary experiments and the half dozen judgments at the 
 opening of each hour for 'warming-up.' 
 
 Table II 
 
 Observer S 
 Thresholds expressed in mm. (i mm. = I.S<t) 
 
 Order of Presentation 
 
 with Two Successive Ivights 
 
 With Moving Light 
 
 Above-below 
 
 Below-above 
 
 Downward 
 
 Upward 
 
 With wider slit. 
 
 9 
 8 
 
 10 
 10 
 
 20 
 20 
 20 
 20 
 
 10 
 
 IS 
 10 
 
 20 
 20 
 15 
 
 Average. 
 
 9.2 
 
 20 
 
 II.7 
 
 18.3 
 
 With narrower slit. 
 
 12 
 13 
 
 13 
 
 23 
 
 8 
 8 
 
 IS 
 
 17 
 
 Average, 
 
 12.S 
 
 18 
 
 8 
 
 16 
 
 Combined average. 
 
 10.3 
 
 19-3 
 
 10.2 
 
 17.4 
 
 Average for the two orders 
 of presentation. 
 
 14.8 
 
 13-8 
 
 The tables show that for Observer B. there was a decided 
 advantage on the side of succession, and for Observer S., no 
 marked advantage either way, although a slight advantage 
 appears on the side of motion. Whatever gain here accrues 
 to 'succession' is not in any wise due to an illusory motion 
 when mere succession was offered. On the contrary, with 
 both observers the presentations, whether of succession or of 
 motion, when just rising above the threshold were perceived 
 as succession far more often than as motion. The usual 
 course of the judgments was this; with the longer times there 
 was a clear discrimination between succession and motion; 
 and then, with briefer times, the presentation was called 
 'successive' or 'different,' meaning that it was not a single 
 simultaneous illumination. Even with actual motion, there- 
 fore, the observer failed to notice the motion, but noticed 
 
272 G. M. STRATTON 
 
 only non-simultaneity. And this lower threshold is entered 
 in the tables even in the case of motion. Where, with B. for 
 example, the thresholds for motion are entered as 300- and 
 350-, this indicates the point at which a departure from simul- 
 taneity was evident; motion was discerned as motion only at 
 400- and 450- respectively; and with S. the detection of motion 
 required a value even higher in its ratio to that of mere 
 succession. 
 
 Furthermore, there is a difference, in some cases quite 
 marked, between the thresholds for the different orders of 
 presentation. Thus for both B. and S. the threshold is 
 lower when, in the case of succession, the upper half of the 
 slit is illuminated before rather than after the lower. And 
 with motion also the direction affects the threshold, although 
 here the two observers do not show a like divergence, since 
 B. best catches motion upward, while with S. motion down- 
 ward has the advantage. But of this phenomenon more will 
 be said in connection with the later experiments. 
 
 III. Experiments with Wheel Apparatus 
 The set of experiments just reported seemed to me incon- 
 clusive because of a growing doubt both of the apparatus and 
 of the method. The puzzling disagreement of results obtained 
 in the different orders of presentation, though the observer 
 did not have to decide which order was given him (to which 
 attention has just been drawn), made me perhaps unwarrant- 
 ably inclined to believe that this inconsistency might be due 
 to some want of rigidity in the instrument. And hesitation 
 arose, too, from the very fact that the values obtained bore, 
 at least in the case of one of the two observers, a relation so 
 decidedly the reverse of that in the classic results. 
 
 Consequently an entirely new apparatus was constructed 
 by a skilful instrument-maker — a pendulum-wheel suggested 
 by a device of Sanford's,^ but departing from it in several 
 respects. From a sheet of aluminum 34 i^i. thick, there was 
 cut a narrow circular rim 20 in. in diameter, having thin poke- 
 like connections with its center. At the center there was a steel 
 axle with ball-bearings resting upon a rigid frame and base, 
 
 'Sanford, American Journal of Psychology, VI., 581 fF. 
 
PERCEPTION OF MOVEMENT 273 
 
 upon which there were levelling screws and a circular spirit 
 level. To the rim of this skeleton wheel was carefully fitted 
 a weight and catches, so that with the weight high upon one 
 side, when one of the catches was released, the wheel revolved 
 until the weight rose high upon the opposite side; and there 
 at its extreme excursion the wheel was caught and the return 
 of the weight prevented. In preparation for the next fall, the 
 rotation of the wheel was completed by hand, and by means 
 of the catch the weight was held high upon the side whence it 
 first fell. 
 
 Upon the axle of the wheel was a screw holding two large 
 black bristol disks, one of which was fixed by additional screws 
 upon the rim, the other being movable and to be set instantly 
 at any position desired. In these disks there were in principle, 
 the same devices for producing succession and movement as 
 with the pendulum before. Thus any order and interval of 
 succession, any direction and speed of movement, could be 
 had at will. Proper scaling in thousandths of a second was 
 provided beforehand by tuning-fork records on the disk, the 
 tuning-fork itself having of course been first carefully cor- 
 rected. 
 
 The method was such as to avoid any extraneous advan- 
 tage accruing, by practice or fatigue, to either of the forms of 
 perception. Experiments upon succession and upon motion 
 were from the first mingled in equal number at every sitting; 
 nor did the observer himself know in any case whether the 
 stimulus to be offered him involved motion or succession 
 merely, nor was he told this after his judgment had been 
 given. But a single movement, a single pair of successive 
 lights, were given for any one judgment. And further it 
 seemed advisable, in view of what had happened in the 
 preceding set of experiments, to simplify the task of the 
 observer and render his judgments more direct and trust- 
 worthy. Hitherto, as already has been indicated, the judg- 
 ments showed some embarrassment before the several possible 
 queries: (i) Was the impression throughout its stretch simul- 
 taneous, or was there some departure from perfect simul- 
 
274 G. M. STRATTON 
 
 tanelty? (2) If there was such a departure, had It the char- 
 acter of a successive illumination of the two halves of the 
 slit; or of a motion? (3) If a succession, did the lower half 
 of the slit flash before or after the upper? (4) If a motion, 
 was this upward, or down? Now the observer is 111 at ease 
 before so many questions, and his nicety of judgment Is apt 
 to be affected by the attempt to keep his mind at once open 
 to so many aspects of the impression, and in the effort to 
 answer secondary questions the answers to primary are often 
 obscured or lost.^ 
 
 Accordingly In this whole group of experiments, even 
 from the start, the observer was asked to confine his attention 
 to the first of the four questions just listed. Additional 
 judgments were occasionally volunteered; and although 
 noted, they were not encouraged. The method again was, 
 at bottom, that of serial groups. Inasmuch as a number of 
 fixed Intervals or durations were selected and repeated; and 
 interspersed with these were frequent cases where the 
 interval or duration was reduced to zero. Yet instead of 
 adhering to a particular interval or duration until its group 
 was complete, and exchanged for a new group and so on until 
 the threshold had been passed, there was no attempt to 
 determine a threshold In the accepted sense, but only by a full 
 display of right and wrong cases, with each interval or dura- 
 tion, to reveal the relative facility of perceiving movement 
 and succession. The following partial series of actual stimuli 
 presented, where the distribution Is quite by chance, will 
 perhaps make clear the procedure just described. 
 0(x motion ( = slmult. Ilium, of entire slit). 
 
 lOo" succession, upper-lower. 
 
 20a- motion, upward. 
 
 300- succession, lower-upper. 
 Oct succession ( = slmult. ilium, of entire slit). 
 
 io<r motion, upward. 
 Oo- succession. 
 
 25or succession, upper-lower. 
 
 ^See the argument offered by Brown ('The Judgment of Difference,' University 
 0/ California Publications in Psychology, I., 28 ff .) for a simple alternative in the question 
 — an argument that has had great weight with me. 
 
PERCEPTION OF MOVEMENT 
 
 275 
 
 
 Table III 
 
 
 (Judgments 
 
 UPON Single Presentations; 
 Observer B 
 
 Discrete Succession 
 
 Direct Vision) 
 
 Interval 1 
 
 Successes 
 
 Failures 
 
 300- 
 
 12 
 
 
 
 2S<r 
 
 12 
 
 
 
 200- 
 
 13 
 
 I 
 
 iS«r 
 
 10 
 
 4 
 
 lo<r 
 
 10 
 
 4 
 
 SO- 
 
 6 
 
 8 
 
 Totals. 
 
 63 
 
 17 
 
 Duration 
 
 Successes 
 
 Failures 
 
 30<r 
 
 8 
 
 4 
 
 25<r 
 
 9 
 
 3 
 
 2O0- 
 
 10 
 
 4 
 
 is<^ ■ 
 
 6 
 
 8 
 
 loo- 
 
 2 
 
 12 
 
 S"- 
 
 Totals. 
 
 6 
 
 41 
 
 8 
 39 
 
 instantaneous 
 
 illums., 50 were judged 'simult. 
 
 Table IV 
 
 ,' 22 'non-simult.' 
 
 (Judgments 
 
 UPON Single Presentations; 
 Observer S 
 Discrete Succession 
 
 Direct Vision) 
 
 Interval 
 
 Successes 
 
 Failures 
 
 30<r 
 
 10 
 
 2 
 
 2S<r 
 
 II 
 
 I 
 
 20(r 
 
 12 
 
 
 
 is<»- 
 
 9 
 
 3 
 
 loo- 
 
 s<»- 
 
 Totals. 
 
 S 
 6 
 
 S3 
 
 Motion 
 
 7 
 
 19 
 
 Duration 
 
 Successes 
 
 Failures 
 
 30(r 
 
 12 
 
 
 
 2S<r 
 
 9 
 
 3 
 
 20<r 
 
 10 
 
 2 
 
 IS"- 
 
 II 
 
 I 
 
 icxr 
 
 5"- 
 
 7 
 _6 
 
 S 
 6 
 
 Totals. 
 
 SS 
 
 17 
 
 Of 72 instantaneous illums., 47 were judged 'simult.,' 26 'non-simult.' 
 
 ^ 'Interval' here and elsewhere means the time between beginning and beginning, 
 or^end and end, of the two successive flashes. 
 
276 
 
 G. M. ST RAT TON 
 
 20a motion upward. 
 
 150- succession, lower-upper. 
 5<T motion, downward. 
 Go- succession. 
 
 300- motion, upward. 
 Go- motion, etc. 
 
 The following tables exhibit the results of these experi- 
 ments. 
 
 Method of Paired Presentations. — Before discussing these 
 results, let me offer also those of another method, used as a 
 check. Here the apparatus and procedure was in all respects 
 as just described, except that there was given, in sequence, 
 two presentations; namely, a zero case — where there was 
 absolute simultaneity of illumination — and a case where there 
 was actual succession or motion. The observer was told that 
 there would be two presentations, one of which would be a 
 simultaneous illumination of the entire slit, the other a 
 departure from such simultaneity; and that his task was 
 simply to tell whether the simultaneous illumination occurred 
 first or second in the pair. The two presentations were then 
 given, with as little time between as could be with the adjust- 
 ment required (about 4 seconds), and no judgment was passed 
 until after the appearance of the second of the pair. The 
 
 
 
 Table V 
 
 
 (Judgment 
 
 BY Pairs; Direct Vis 
 
 sign) 
 
 
 
 Observer B 
 
 
 
 Discrete Succession 
 
 
 Interval 
 
 
 Successes 
 
 Failures 
 
 20<r 
 
 
 II 
 
 I 
 
 I5<^ 
 
 
 10 
 
 2 
 
 lOff 
 
 
 8 
 
 4 
 
 Totals. 
 
 
 _6 
 
 35 
 
 Motion 
 
 6 
 
 13 
 
 Duration 
 
 
 Successes 
 
 Failures 
 
 200- 
 
 
 7 
 
 5 
 
 IS**" 
 
 
 8 
 
 4 
 
 10(r 
 
 
 8 
 
 4 
 
 Totals. 
 
 
 _4 
 27 
 
 8 
 21 
 
PERCEPTION OF MOVEMENT 
 
 277 
 
 
 Table VI 
 
 
 (Judgment by Pairs; Direct 
 
 Vision) 
 
 
 Observer S 
 
 
 
 Discrete Succession 
 
 
 Interval 
 
 Successes 
 
 Failures 
 
 ZO(T 
 
 14 
 
 
 
 IS'' 
 I0<r 
 
 10 
 II 
 
 4 
 3 
 
 S<' 
 Totals. 
 
 II 
 
 46 
 
 Motion 
 
 _3 
 10 
 
 Duration 
 
 Successes 
 
 Failures 
 
 200- 
 
 13 
 
 I 
 
 iS«r 
 loo- 
 Totals. 
 
 13 
 7 
 6 
 
 39 
 
 I 
 
 7 
 
 8 
 
 17 
 
 observer was ignorant of the actual order, and this order itself 
 was irregularly changed. The following tables exhibit the 
 results obtained. 
 
 Examination of the results of these two different pro- 
 cedures discloses that with neither of the observers, nor by 
 either method, is there an advantage for motion over succes- 
 sion. And consequently the new apparatus and simplified 
 task for the observer brings the same general relation of 
 values as were obtained in the first set of experiments with 
 the pendulum. Observer B. now, as before, can more readily 
 detect a departure from simultaneity in the illumination when 
 departure actually is of succession rather than of motion. 
 Observer S. again, for a part of the set — when there were 
 single presentations — shows about equal facility with either 
 kind of stimulus; but with double presentations shows 
 greater ease in dealing with successsion. 
 
 Any one interested in method, and in the psychological 
 indications arising from differences therein, will perhaps feel 
 inclined to compare more closely the outcome by single 
 presentation (Tables III. and IV.) and by double (Tables V. 
 and VI.). It will be seen that Observer B. has, so far as dis- 
 crete succession is concerned, a slightly greater success by 
 the method of double presentation, and with motion he shows 
 
278 
 
 G. M. STRATTON 
 
 a decidedly higher ratio of successes to failures when the pre- 
 sentation is in pairs. Observer S., when discrete sequence 
 is offered, succeeds markedly better with pair-presentations 
 than with single-presentations; when motion is offered, the ad- 
 
 Table VII 
 
 Observer B. Direct Vision 
 With Discrete Succession 
 
 Time Interval 
 
 Judgment by Single Presen- 
 tation 
 
 Judgment by Double Presen- 
 tation 
 
 
 Successes 
 
 Failures 
 
 Successes 
 
 Failures 
 
 20<T 
 
 loo- 
 
 13 
 10 
 10 
 
 6 
 
 I 
 
 4 
 4 
 
 8 
 
 II 
 
 10 
 
 8 
 6 
 
 I 
 
 2 
 
 4 
 6 
 
 Totals 
 
 39 
 
 17 
 
 35 
 
 13 
 
 Ratio of successes to failures 
 
 2.3 : I 
 
 2.7:1 
 
 With Motion 
 
 Duration 
 
 Judgment by Single Presen- 
 tation 
 
 Judgment by Double Presen- 
 tation 
 
 
 Successes 
 
 Failures 
 
 Successes 
 
 Failures 
 
 20cr 
 loo- 
 
 10 
 
 6 
 2 
 6 
 
 4 
 
 8 
 
 12 
 
 8 
 
 7 
 8 
 8 
 4 
 
 s 
 
 4 
 4 
 
 8 
 
 Totals 
 
 24 
 
 32 
 
 27 
 
 21 
 
 Ratio of successes to failures 
 
 0.7s : I 
 
 1.3 :l 
 
 Table VIII 
 
 Observer S. Direct Vision 
 With Discrete Succession 
 
 Interval 
 
 Judgment by Single Presen- 
 tation 
 
 Judgment by Double Presen- 
 tation 
 
 
 Successes 
 
 Failures 
 
 Successes 
 
 Failures 
 
 200- 
 IS<r 
 IOC- 
 
 12 
 
 9 
 
 5 
 6 
 
 
 3 
 7 
 6 
 
 14 
 10 
 II 
 II 
 
 
 4 
 
 3 
 3 
 
 Totals 
 
 32 
 
 16 
 
 46 
 
 10 
 
 Ratio of successes to failures 
 
 2 : I 
 
 4.6 : I 
 
PERCEPTION OF MOVEMENT 
 
 279 
 
 With Motion 
 
 Duration 
 
 Judgment by Single Presen- 
 tation 
 
 Judgment by Double Presen- 
 tation 
 
 
 Successes 
 
 Failures 
 
 Successes 
 
 Failures 
 
 20cr 
 
 loo- 
 
 10 
 II 
 
 7 
 6 
 
 2 
 
 I 
 
 5 
 6 
 
 13 
 
 13 
 
 7 
 
 6 
 
 I 
 I 
 
 7 
 8 
 
 Totals 
 
 34 
 
 14 
 
 39 
 
 17 
 
 Ratio of successes to failures 
 
 2.4:1 
 
 2.3 : I 
 
 vantage for the method in which pairs of presentations occur 
 disappears. The following tables (VII. and VIII.) in which 
 the comparable values are isolated and set side by side and 
 summed, will, I trust, make this more clear. 
 
 In general it would appear that a greater fineness of per- 
 ception is possible by the method of paired presentation than 
 by that of single presentation. And furthermore there is 
 noticeable in the values obtained by the method of paired 
 presentations a somewhat greater regularity; the number of 
 successes or of failures keeps better step with the change in the 
 time-interval, the correlation between the interval employed 
 and the success of perception is closer when this method is 
 employed than when its rival. 
 
 Experiments with Eccentric Vision. — Such was the evi- 
 dence upon the main problem, so far as a foveal vision is 
 concerned. Experiments were tried also with eccentric vision, 
 the observer fixating with both eyes a point 20° to the left 
 of the slit in which the illumination appeared. Tables IX. 
 
 Table IX 
 
 Experiments with Eccentric Vision 
 Observer B 
 
 Time 
 
 Discrete Succession 
 
 Motion 
 
 Successes 
 
 Failures! 
 
 [Successes 
 
 Failures 
 
 300- 
 250- 
 20<r 
 15<r 
 
 11 
 
 8 
 6 
 8 
 
 I 
 
 4 
 6 
 
 4 
 
 10 
 
 10 
 
 6 
 
 8 
 
 2 
 2 
 
 6 
 
 4 
 
 Totals. 
 
 33 
 
 15 
 
 34 
 
 14 
 
28o 
 
 G. M. STRATTON 
 Table X 
 
 Experiments with Eccentric Vision 
 Observer S 
 
 Time 
 
 Discrete Succession 
 
 Motion 
 
 Successes 
 
 Failures 
 
 Successes 
 
 Failures 
 
 30ff 
 25<r 
 20<r 
 
 lOff 
 
 4 
 
 3 
 
 II 
 
 9 
 9 
 9 
 
 O 
 I 
 I 
 
 3 
 3 
 3 
 
 4 
 
 4 
 
 II 
 
 9 
 6 
 
 4 
 
 O 
 O 
 
 I 
 
 3 
 6 
 8 
 
 Totals. 
 
 45 
 
 II 
 
 38 
 
 i8 
 
 and X. show the results of these experiments. The presen- 
 tations were always by- pairs; the procedure was in all other 
 respects as last described. 
 
 Under these conditions it is apparent that, with Observer 
 B., there was almost equal success with either kind of stimulus, 
 although the values indicate in both cases a higher threshold 
 than with direct vision. With Observer S., there is somewhat 
 greater facility in dealing with succession than with motion, 
 although here the values indicate no rise of the threshold. 
 Thus in this region as in others, succession is certainly at no 
 disadvantage as compared with movement. 
 
 Absolute Time in the Results. — As for the absolute time- 
 values obtained in these experiments, they run considerably 
 lower than we have been accustomed to regard as obtaining 
 here. It will be recalled^ that Exner found 150- to be the 
 duration needed for perceiving motion; 450-, for discrete suc- 
 cession. Bourdon recognized motion at 270-; with discrete 
 succession right judgments exceeded wrong at 20o-; the time 
 order of succession was caught with certainty at 480-. Weyer 
 found a slight drag at i2o-, a 'flicker' at 250—300-, clear suc- 
 cession at 43o"-53o-. Charpentier discerned succession at 270-. 
 
 In the portion of the present experiments where the vision 
 was direct and the conditions otherwise were most favorable. 
 Observer S., even with so brief an interval as 50-, distinguished 
 succession from simultaneity 11 times in 14 trials {i. e., 80 per 
 cent, of the judgments were correct; cf. Table VI., p.) 277. B., 
 
 1 See pp. 263 ff. of the present paper. 
 
PERCEPTION OF MOVEMENT 281 
 
 when the interval was lOa, correctly made this distinction in 10 
 of the 14 cases offered him (70 per cent.; cf. Table III., p. 275, 
 and Table V., p. 276, where two thirds of B.'s answers were cor- 
 rect, with I0(t). And, again, with indirect vision, an interval of 
 but 50- still permitted Observer S. to give correct judgments 
 regarding discrete succession in 9 cases out of 12 (75 per cent.; 
 cf. Table X., above. 
 
 Such a lowering of the time-threshold to about one third 
 of what usually has been considered its lowest value (to 50-, 
 as against 150-), if motion be regarded as offering the finest 
 measure of the time-threshold; or to about one ninth of its 
 accepted value (to 50-, as against 450-) if succession be taken 
 as criterion, — this lowering is to be ascribed to a combination 
 of causes: perhaps (i) to the method of presentation, inas- 
 much as examples both of simultaneity and of non-simul- 
 taneity, it was known, would be offered, and the observer had 
 simply to affirm which was which; and (2) to the instru- 
 mental arrangement, — whereby there was given an immediate 
 juxtaposition of successive lights, yet without fusion — an 
 arrangement analogous to the successful 'vernier-method' in 
 experiments with space; and (3) to practice, since with each 
 subject a far greater number of experiments was completed 
 than has been usual in this field. 
 
 Some might feel tempted to say that the lowering of the 
 values arose from the fact that the judgments here given 
 were not due in the first instance to time-perception at all; 
 that they were time-judgments, but derived from an appear- 
 ance not primarily temporal — derived perhaps from intensive 
 differences in the light at the point of junction of the two 
 halves of the slit. I have myself tried impartially to enter- 
 tain a supposition of this kind, but after serving long as an 
 observer in the experiment the phenomenon has seemed too 
 me clearly a time-phenomenon; has seemed to be the con- 
 scious presence or absence of precise and punctual synchro- 
 nousness in the luminous slit. There appeared to me no 
 intensive difference between a pair of lights that were exactly 
 simultaneous and a pair in which succession was just dis- 
 cernible; nor is it probable, although still conceivable, that 
 such a difference was there. 
 
282 
 
 G. M. STRATTON 
 
 Optimal Orders or Directions. — To one other aspect of the 
 observers' judgments attention might be called, — namely to 
 an occasional partiality which the observers had for a par- 
 ticular order of succession, a particular direction of movement. 
 If we segregate the judgments passed upon a succession 
 actually 'above-below,' and again the judgments passed upon 
 a succession actually 'below-above'; and likewise with motion 
 downward and motion upward, we obtain the values set 
 forth in Tables XI. and XII. 
 
 Table XI 
 
 Observer B 
 Segregation of Different Orders and Directions 
 
 
 Succession 
 
 Motion 
 
 
 Time 
 
 Above-below 
 
 Below-above 
 
 Downward 
 
 Upward 
 
 
 
 Suc- 
 cesses 
 
 Fail- 
 ures 
 
 Suc- 
 cesses 
 
 Fail- 
 ures 
 
 Suc- 
 cesses 
 
 Fail- 
 ures 
 
 Suc- 
 cesses 
 
 Fail- 
 ures 
 
 
 300- 
 2S<r 
 20<r 
 
 IOC- 
 
 6 
 6 
 7 
 4 
 6 
 
 3 
 
 
 
 
 
 3 
 
 I 
 
 4 
 
 6 
 6 
 6 
 6 
 4 
 3 
 
 
 
 I 
 
 I 
 3 
 4 
 
 4 
 
 5 
 5 
 4 
 
 2 
 
 2 
 I 
 
 2 
 
 3 
 S 
 5 
 
 4 
 4 
 5 
 2 
 
 
 4 
 
 2 
 2 
 2 
 5 
 
 7 
 3 
 
 CO 
 
 ■ 1"? 
 
 B 
 
 Total. 
 
 32 
 
 8 
 
 31 
 
 9 
 
 22 
 
 18 
 
 19 
 
 21 
 
 
 zoo- 
 ISO- 
 IOC- 
 
 6 
 S 
 4 
 3 
 
 
 I 
 
 2 
 3 
 
 5 
 5 
 4 
 3 
 
 I 
 I 
 2 
 3 
 
 2 
 5 
 4 
 
 
 4 
 I 
 
 2 
 6 
 
 5 
 3 
 4 
 4 
 
 I 
 
 3 
 2 
 2 
 
 Presenta- 
 tion in 
 pairs— di- 
 rect vis- 
 ion. 
 
 Total. 
 
 18 
 
 6 
 
 17 
 
 7 
 
 II 
 
 13 
 
 16 
 
 8 
 
 
 300- 
 2S(r 
 
 ZOiT 
 
 5 
 4 
 3 
 4 
 
 I 
 
 2 
 
 3 
 2 
 
 6 
 4 
 3 
 4 
 
 
 
 2 
 
 3 
 
 2 
 
 5 
 5 
 2 
 2 
 
 I 
 
 I 
 4 
 4 
 
 5 
 5 
 4 
 6 
 
 I 
 
 I 
 2 
 
 
 Presenta- 
 tion in 
 pairs— in- 
 direct vis- 
 ion. 
 
 Total. 
 
 16 
 
 8 
 
 17 
 
 7 
 
 14 
 
 10 
 
 20 
 
 4 
 
 
 Grand total. 
 
 66 
 
 22 
 
 65 
 
 23 
 
 47 
 
 41 
 
 55 
 
 33 
 
 
 In Table XII. (Observer S.) it will be noticed that with 
 succession, when the order is above-below the total number of 
 successes is 81, as against 63, when the order is reversed 
 (below-above); and likewise with motion, when direction is 
 downward the successes are 74, as against 58 when the direc- 
 tion is reversed. And this relation that appears in the grand 
 
PERCEPTION OF MOVEMENT 
 
 Table XII 
 
 Observer S 
 Segregation of Different Orders and Directions 
 
 283 
 
 
 Succession 
 
 Motion 
 
 
 Time 
 
 Above-below 
 
 Below-above 
 
 Downward 
 
 Upward 
 
 
 
 Suc- 
 cesses 
 
 Fail- 
 ures 
 
 Suc- 
 cesses 
 
 Fail- 
 ures 
 
 Suc- 
 cesses 
 
 Fail- 
 ures 
 
 Suc- 
 cesses 
 
 Fail- 
 ures 
 
 
 300- 
 250- 
 200- 
 
 I5<T 
 I Off 
 
 5 
 6 
 6 
 6 
 5 
 4 
 
 I 
 
 
 
 
 I 
 
 2 
 
 5 
 5 
 6 
 
 3 
 
 
 2 
 
 I 
 I 
 
 
 3 
 6 
 
 4 
 
 6 
 
 5 
 6 
 6 
 4 
 3 
 
 
 I 
 
 
 
 
 2 
 
 3 
 
 6 
 4 
 4 
 
 5 
 3 
 3 
 
 
 
 2 
 2 
 I 
 
 3 
 3 
 
 CO 
 
 5-1 S 
 3 ' n 
 
 • a.0 
 
 Total. 
 
 32 
 
 4 
 
 21 
 
 IS 
 
 30 
 
 6 
 
 25 
 
 II 
 
 
 20ff 
 
 lOcr 
 5*^ 
 
 7 
 6 
 6 
 6 
 
 
 I 
 
 I 
 I 
 
 7 
 4 
 
 5 
 5 
 
 
 
 3 
 2 
 2 
 
 6 
 7 
 5 
 4 
 
 I 
 
 
 
 2 
 3 
 
 7 
 6 
 
 2 
 2 
 
 
 
 I 
 5 
 5 
 
 Presenta- 
 tion by 
 pairs— di- 
 rect vis- 
 ion. 
 
 Total. 
 
 25 
 
 3 
 
 21 
 
 7 
 
 22 
 
 6 
 
 17 
 
 II 
 
 
 3 Off 
 2Sff 
 20ff 
 
 I Off 
 
 5<^ 
 
 2 
 2 
 5 
 4 
 6 
 
 5 
 
 
 
 
 I 
 2 
 
 
 I 
 
 2 
 I 
 6 
 S 
 3 
 4 
 
 
 
 I 
 
 
 I 
 
 3 
 2 
 
 2 
 2 
 6 
 
 S 
 5 
 2 
 
 
 
 
 I 
 
 I 
 4 
 
 2 
 2 
 
 5 
 4 
 
 I 
 2 
 
 
 
 I 
 
 2 
 5 
 4 
 
 i?- £ 
 
 0*0 3 
 
 •■J -1 !!i 
 
 O-I.B 
 B 3 
 
 Total. 
 
 24 
 
 4 
 
 21 
 
 7 
 
 22 
 
 6 
 
 16 
 
 12 
 
 
 Grand total. 
 
 81 
 
 II 
 
 63 
 
 29 
 
 74 
 
 18 
 
 58 
 
 34 
 
 
 totals also appears In the sub-totals obtained by each separate 
 method and region of the retina; there is invariably greater 
 success with the order 'above-below,' invariably greater 
 success with the direction downward. 
 
 In Table XL (Observer B.), the partiality is exceedingly 
 faint, if not entirely absent; certainly absent when succession 
 is being offered, for here the total number of right judgments 
 when the order is 'above-below' is almost exactly the same 
 as with the reverse order (66 as against 65) ,and the sub-totals 
 show a like approximation. But with motion there is perhaps 
 a slight partiality for the upward direction (55 successes as 
 against 47 with motion downward), — a partiality, however, 
 so phlegmatic that a mere change of method from double to 
 single presentation is sufficient to reverse it. 
 
2S4 
 
 G. M. ST R ATT ON 
 
 Nor is the partiality confined to diflFerences in vertical 
 direction; it appears in experiments with the horizontal direc- 
 tion as well. With Observer S., in whom the difference in 
 result for the different orders of appearance was most pro- 
 nounced, supplemental experiments were tried in which the 
 stationary slit {i. <?., the slit upon the front screen) lay in a 
 horizontal instead of a vertical position, and with the rest 
 of the apparatus so adjusted as to give illuminations of the 
 two halves of the slit in the order 'left-right,' as well as in 
 the order 'right-left.' And also (to answer the question 
 whether the advantage might in any way be due to the fact 
 that the stationary slit was a parallelogram and so permitted 
 the half of the illumination that came from that portion of 
 the radial slit lying nearer the center of the wheel to appear 
 an almost infinitesimally longer period than the illumination 
 from the more distant portion), experiments were performed 
 with two different characters of stationary slit, — in the one 
 case, as hitherto, with sides exactly parallel; in the other case, 
 with sides slightly departing from this arrangement, so that, 
 
 Table XIII 
 
 Observer S. Direct Vision, Pair Presentation, Horizontal Direction 
 
 Succession 
 
 Time 
 
 I,eft-right 
 
 Right-left 
 
 
 Successes 
 
 Failures 
 
 Successes 
 
 Failures 
 
 
 \0<T 
 
 5<^ 
 
 II 
 
 6 
 
 I 
 18 
 
 12 
 19 
 
 
 
 5 
 
 With paral- 
 lelogram slit. 
 
 
 17 
 
 19 
 
 31 
 
 5 
 
 
 IOC- 
 
 9 
 6 
 
 3 
 6 
 
 12 
 
 12 
 
 
 
 
 With radial 
 slit. 
 
 
 IS 
 
 9 
 
 24 
 
 
 
 
 Total. 
 
 32 
 
 28 
 
 55 
 
 5 
 
 
 had they been extended, they would have met at the center 
 of the wheel (t. e., a radial slit instead of a narrow parallel- 
 ogram). Thus both halves of the slit gave absolutely equal 
 durations of illumination. In all other respects the pro- 
 cedure was unchanged. Table XIII. shows the outcome of 
 these experiments. 
 
PERCEPTION OF MOVEMENT 
 
 285 
 
 The advantage, which with the vertical slit was for the 
 order 'above-below,' here reappears strong, and for the order 
 * right-left.' Out of 60 trials with this particular order, but 
 5 errors were made; whereas for a like number of trials with 
 the opposite order 28 errors were made. 
 
 These partialities had already been noticed, as I have said, 
 in the earlier experiments, with the pendulum; and in Table 
 XIV. they are set forth in conjunction with those found in 
 the later experiments. 
 
 Table XIV 
 
 Unconscious Partialities for Particular Orders and Directions 
 
 (/. I?., the order or direction in which there was heightened facility, or lowered 
 threshold.) 
 
 
 I In Case of Succession 
 
 In Case of Motion 
 
 Observer 
 
 Earlier Experi- 
 ments (Pendulum) 
 
 I,ater Experi- 
 ments (Wheel) 
 
 Earlier Experi- 
 ments (Pendulum) 
 
 I,ater Experi- 
 ments (Wheel) 
 
 B 
 
 S 
 
 above-below 
 
 (slight) 
 above-below 
 
 no preference 
 
 above-below 
 right-left 
 
 upward 
 downward 
 
 upward (slight) 
 downward 
 
 The suspicion with which I closed the earlier set of experi- 
 ments, that such partiality was a mere appearance due to 
 some aberration in the apparatus^ was thus evidently un- 
 warranted. The unequal facility of dealing with the rival 
 orders and rival directions reappears in the later experiments 
 and in the same general sense: the preference for upward 
 motion in the earlier experiments in answered by a preference 
 for the upward motion in the later; the preference for the 
 succession 'above-below' is answered by a preference for 
 this same succession. Only in B., in whom the tendency 
 is weak at best, the partiality grows less in the later experi- 
 ments, passing away entirely in the case of succession. It 
 is thus an individual matter; for the different observers do 
 not agree in their partialities; and of course it is not to be 
 regarded as a conscious liking. No observer expressed any 
 preference for an order or a direction. By 'partiality' is 
 meant, then, no emotional difference, but merely a greater 
 
 ^See p. 272. 
 
2S6 G. M. STRATTON 
 
 ability of perception or of discrimination. It seems to have 
 some similarity (though I can hardly believe that there is 
 any causal connection between the two) to the greater 
 aptitude for detecting a departure from linear continuity 
 when the departure was upon the right, racher than upon the 
 left, of the standard vertical;^ or to the personal differences 
 in dealing with successive shocks and successive clicks which 
 others have found, ^ In explanation of the partialities appear- 
 ing in the present experiments, I feel tempted to believe that 
 they may be due to certain obscure habits or tricks of atten- 
 tion. It is probable that, other things equal, some persons 
 are slightly more ready to attend to an object in the upper 
 half of the visual field than in the lower; while with the others 
 the reverse may be true. One whose attention had any such 
 inclination would seem to have the foundation for a partiality 
 like that of the present experiment. It is significant, in this 
 connection, that with S., the advantage which a particular 
 order of succession holds is shared by the corresponding 
 direction of motion. With B., however, this is not true, 
 at the very time when succession in the order 'above-below* 
 had an advantage, the advantage in the region of motion 
 lay with the direction opposed to this, lay namely with motion 
 upward. 
 
 V. The Precise Relation between Succession and 
 
 Motion 
 Turning now to the main question, which serves as a title 
 to this paper, I believe we shall be more likely to succeed in 
 answering it if we divide and attend to each division sepa- 
 rately, (i) Is the consciousness of rapid motion (such as 
 we have had in these experiments) intimately bound up with 
 the consciousness of succession; or are they distinct and even 
 independent mental processes.? (2) Are these mental proc- 
 esses, whatever their relation may be, rightly designated as 
 sensations? These are separate questions, although the an- 
 
 ^See 'A New Determination of the Minimum Visibile,' etc., Psychological 
 Review, VII., 429; and 'Visible Motion and the Space Threshold,' Psychological 
 Review, IX., 433. 
 
 ^Hamlin,/On the Least Observable Interval,' etc., Amer. Journ. of Psychol., VI. 
 564 ff. Drew, 'Attention,' Amer. Journ. of Psychol., VII., 533 ff. 
 
PERCEPTION OF MOVEMENT ^S*/ 
 
 swer to one may involve or determine the answer to the other. 
 
 In answer to the preceding of these questions, one may 
 speak first in negatives. I am inclined to believe that the 
 facts brought out by the present experiments, in conjunction 
 with what has been done before, very nearly annul the sup- 
 posed evidence for the independence of succession and motion; 
 at least so far as the claim for the priority of motion is con- 
 cerned. For it is now apparent that the detection of motion 
 is nicer than that of discrete succession neither on the spatial 
 side nor yet upon the temporal. Motion cannot be discerned 
 within space-limits too small for discriminating positions; 
 nor within time-limits too narrow to permit the conscious 
 distinction of instants.^ 
 
 On the other hand, a certain claim might now be set up 
 for the priority of discrete sequence. For upon the whole, 
 the threshold when 'succession' was employed was lower than 
 when there was motion. Moreover this meant not simply 
 that an external and objective succession broke up the appear- 
 ance of simultaneity more readily than did motion, but that 
 the observers were inclined, under the conditions here ar- 
 ranged, and with continued practice, to give their judgment 
 of such non-simultaneity in the form 'sequence' long before 
 they were ready to declare it to be 'motion.' And, indeed, 
 this seems to me in keeping with what we know from a wide 
 variety of experiments: in keeping with the greater ease in 
 deciding the vaguer — the more abstract — feature of an im- 
 pression; for the decision as to the more definite, the more 
 concrete, characteristics comes later and with more difficulty. 
 Since, in contradiction to Berkeley's principle, we can tell 
 that a pressure has changed, far more readily than we can 
 decide whether it has become heavier or lighter;^ and since 
 
 ^Nor, it might be added, can motion be noticed at an intensity too weak for 
 the detection of a motionless light. Contrary to a certain prejudice aroused by the 
 attention which moving objects so readily command, a moving light, when attention 
 is full upon it, cannot be seen at so low an intensity of stimulus, as can a stationary 
 light. Here again the supposed sensory-advantage of motion proves ill-claimed. See 
 'Some Experiments on the Perception of the Movement, Color, and Direction of 
 Lights,' etc., in the Johns Hopkins Studies in Philosophy and Psychology, No. 2, pp. 88 f. 
 
 2 See 'Ueber die Wahrnehmung von Druckanderungen,' etc., in Wundt's Philos. 
 Studien, XII., 534 ff., 539. 
 
288 G. M. STRATTON 
 
 we show a like tendency in many other fields; it would not 
 be surprising if, at bottom, it were easier to decide that 
 simultaneity had in some general way been violated, — that 
 the impression was in some vague form successive, — perhaps 
 even without being of a succession distinctly discrete — than to 
 decide whether it was succession plus those special and par- 
 ticular marks of continuity both in space and time that char- 
 acterize motion. Succession means merely change; discrete 
 succession means change with some temporal interim or 
 cessation of the process, motion means that the change has 
 no such temporal interim, and furthermore that there is 
 perfect continuity, along with shift, in the space involved. 
 But such an account implies some weakening of the claim to 
 priority on the part of discrete succession; for this is almost, 
 though not quite, as advanced a specification of succession 
 as motion is. 
 
 The positive side of the answer to the question as to the 
 relation of sequence and motion would therefore seem to me 
 to be this: that motion involves as a constituent element 
 sequence although not discrete sequence; the rather it in- 
 volves sequence particularized in a way soon to be described; 
 but in any event, that motion is the more special and ad- 
 vanced form of the sequence-consciousness. Yet it is the 
 one to which the mind rushes headlong. For just as in our 
 perception we hasten to fill out the lacunae of impression, 
 even at the risk of illusion; just as it is, in one sense, far 
 easier to see as a man the form and color which a human being 
 offers to the eye and color; and yet this interpretation, while 
 most difficult to suppress, is an advance and addition to the 
 consciousness of mere form and color — so with motion. The 
 rapid sensory sequences which nature offers us in any one 
 region of space are predominantly continuous sequences — 
 continuous in both space and time; the flutter of leaves and 
 of grass, the darting of birds and of insects, the quick action 
 of eyes and lips and fingers in men about us. And so the 
 mind becomes accustomed to this manner of interpreting all 
 rapid change; it interprets it instinctively as motion. But 
 
PERCEPTION OF MOVEMENT 289 
 
 this precipitancy of nterpretation should deceive the psy- 
 chological analyst no more in the one case than in the other. As 
 little as we should now be inclined to say that the perception 
 of a cow is independent of the consciousness of extensity, 
 although most of us see cows in a field more readily than red- 
 extensities there; so little in the end will we be inclined to 
 regard motion, for all its greater readiness to arise in the 
 mind, as independent of sequence or succession. Motion is 
 different from sequence, whether discrete or continuous, but 
 only inasmuch as it Is sequence made specific, made more 
 concrete by giving it a peculiar spatial character. The rela- 
 tion of those processes, so far as complexity and dependence 
 is concerned, might be illustrated by the accompanying 
 diagram. 
 
 Some Temporal Connection 
 
 Simultaneity Sequence 
 
 Discrete Succession j Continuous Succession 
 
 Unbroken change other Unbroken change of place 
 
 than that of place (motion) 
 
 When the mind is not on its guard, it rushes, on the slightest 
 excuse, through all the intermediate stages to a conviction 
 of movement. In that sense, the motion-interpretation Is 
 simpler; It Is more natural, it is the course in which experience 
 has drilled us. But the mind needs a more intense stimula- 
 tion, it requires an Impression whose diiferential marks are 
 more pronounced, if the mind is to be, not merely more 
 confident, but actually more accurate in detecting the real 
 character of the change presented to it. Practiced observers 
 therefore when confronted with faint changes such as occurred 
 in these experiments unwittingly fall back, sooner or later, 
 on the less commital form of judgment — that of 'succession' 
 merely; passing on to the farther specification, — the judg- 
 ment that the succession Is actually of 'motion' — only when 
 the Impression has become more clear. They have become 
 schooled out of their impulsive readiness to take all rapid 
 
290 G. M. STRATTON 
 
 visual change (unless there are unmistakable signs to the 
 contrary) as movement.^ 
 
 But the fact that, on the whole, my observers reserved 
 the judgment 'movement' for the more pronounced and 
 definite stimulations, and usually formed only the vaguer 
 judgment 'sequence' or 'succession' or 'some departure from 
 simultaneity,' when the impression was approaching its 
 liminal value, — this does not touch the farther question as 
 to what form of stimulus will best furnish the definiteness of 
 impression that permits even the vaguer judgment to be 
 passed reliably. It would seem from the present experiments 
 that with trained observers discrete succession customarily 
 gives a much greater shock, a less mistakable violation of 
 simultaneity, than does continuous succession (motion). A 
 less time suffices to make discrete succession seem non- 
 simultaneous, than is required to make motion distinct from 
 simultaneity. At times this is not so; the just-perceptible 
 violation of simultaneity comes equally well from either 
 source. But the other relation is perhaps the rule. Indeed, 
 this would seem in keeping with the general intensification 
 and shock and start which interruptions give, and the greater 
 ease and smoothness of continuous change. 
 
 To sum up then the answer to the first of our questions. 
 Whether the consciousness of rapid motion is intimately 
 bound up with the consciousness of succession, or is inde- 
 pendent; it is this: that the two are intimately conjoined^ the 
 judgment of motion being a farther specification {more complex^ 
 and yet easier) of the judgment of sequence. The judgment of 
 motion has a certain priority, in the sense that it is both more 
 complex and also more readily performed, much as the move- 
 ment of four fingers of a hand is easier, though more complex, 
 than the movement of one finger alone. The judgment of 
 succession, however, has its own priority, inasmuch as it is the 
 simpler, and requires a less lasting stimulation to evoke it. 
 
 And the answer to this first question has perhaps already 
 
 ^This naive readiness is well seen in the almost inevitable impression of 'winking' 
 which a rapid intermission of light produces. The twinkling of stars with its sense 
 of motion is, I doubt not, three fourths motion-illusion due to rapid intensive change, 
 the other fourth the actual shift that the light undergoes by changes of refraction. 
 
PERCEPTION OF MOVEMENT 291 
 
 suggested the answer I feel bound to give to the second, — 
 the question whether the consciousness of succession or of 
 movement (even when rapid) is to be designated as sensation. 
 In dealing here with out consciousness of succession and of 
 movement the expression 'judgment' has often been em- 
 ployed; and yet there is hardly any need of warning that 
 the core-substance of succession or of motion, as they here 
 appear, is not a mere judgment, but has a strong admixture 
 of sensation. We see the succession, we see the movement, 
 whatever judgments we may pass upon it. But Inasmuch as 
 the conscious succession, the conscious movement, involves a 
 certain relating and interpreting (as I have attempted to 
 indicate, especially in regard to motion), it would seem prefer- 
 able — if one were to limit himself to the usual alternatives-^ 
 to regard it as a perception, rather than as either a sensation or a 
 judgment. The sensory impression is here grasped in its simple 
 relations of time, it is here interpreted and felt to belong to 
 a certain familiar type of experience. And just as we speak 
 of the perception of a cow, and the sensation of red; so too 
 in principle (though now the span between the bare impression 
 and Its 'form' or 'system' is almost too small for observation) 
 we must distinguish the perception of succession (or the per- 
 ception of motion) from the sensations which are its in- 
 gredients and sign. The term 'sensation,' I take it, desig- 
 nates a sheer abstraction, designates the 'matter' of sensory 
 impressions as distinguished from their 'form.' If then the 
 peculiar meaning of sensation and its distinction from per- 
 ception (as a consciously formed or organized Impression) 
 is to be preserved, it seems best to regard the conscious process 
 with which we have here been so long dealing as a perception 
 or percept, rather than as a sensation. 
 
 Yet perhaps the negative side of the argument — that these 
 processes are not mere sensations — Is perhaps more convincing 
 than the positive side, which urges that they be called 'per- 
 ceptions.' For the term 'perception' covers an Idea that 
 must in time be resurveyed and subdivided. We are sadly in 
 need of a more precise expression here, and were it not for a 
 natural hesitation at new terms, one would feel tempted to 
 
 Onlwtslly (if Callfomla 
 
292 G. M. STRATTON 
 
 propose that (since no external object is here 'received' or 
 'taken' through the sense, or the sensation, — which is a 
 prominent element in at least the earlier idea of perception) 
 we designate these simple organizations of sensory 'matter' 
 where no physical 'thing' is caught, as 'infra-percepts,' 
 or 'aesthamorphs.' For there is here the need of marking a 
 stage where sensation has been organized, yet not organized 
 into a perceptive object or thing. 
 
 Summary 
 
 1. When successive lights are exactly juxtaposed spatially, 
 motion that is just perceived does not occupy a briefer time 
 than mere succession that is just perceived. 
 
 2. On the contrary, practiced observers can usually per- 
 ceive mere succession whose time-limits are less than those of 
 just-noticeable motion. 
 
 3. And the judgment of such observers more readily takes 
 a form affirming mere non-simultaneity rather than motion. 
 
 4. Under the conditions here arranged, a succession of 
 lights but 50- apart could be discerned by the writer in 80 per 
 cent, of the trials, — and the other observer also detected 
 succession considerably below the limits hitherto accepted as 
 obtaining in this region, 
 
 5. For each person, there is usually an optimal direction 
 of succession or of movement. That is, a succession or move- 
 ment in the order above-below (or the reverse) may be noticed 
 at a rate at which the succession or motion in the opposite 
 direction is quite imperceptible. This preferred order is not 
 the same for all persons, and in the same individual the pre- 
 ferred order for succession need not be the preferred order 
 for motion. 
 
 6. The general relations described above appear to obtain 
 in eccentric as well as in foveal vision, although the absolute 
 values in the two regions may differ. 
 
 7. A change of method from that of single presentations 
 to the method of paired presentations generally brings about 
 both a nicer and a more constant recognition of the phenome- 
 non offered. 
 
PERCEPTION OF MOVEMENT 293 
 
 8. The relation between the consciousness of succession 
 and that of motion Is exceedingly Intricate. The conscious- 
 ness of motion is a farther 'specification' of the consciousness 
 of succession, somewhat as the consciousness of Increase or 
 decrease of pressure is a farther specification of the conscious- 
 ness of mere change of pressure. The two orders of percep- 
 tion are certainly distinct, although quite as certainly not 
 independent, since the more specific apprehension always in- 
 volves the less specific, but not vice versa. The seeing of 
 motion Is a more elaborate, and yet at the same time more 
 facile mental act, than the seeing of mere succession. The 
 headlong readiness to interpret all neighboring successions 
 as motions, to which the world has trained the mind, can 
 however be checked by special and cautious observation, and 
 then the essentially simpler judgment or perception, that of 
 mere succession, is the one that more readily arises. 
 
 9. The consciousness of rapid motion or of rapid succession 
 is not a mere sensation, nor Is it a mere judgment, nor again 
 is It a perception In the older historic meaning of the term. 
 It is rather a sensation or group of sensations consciously 
 organized, and yet not organized into anything so concrete 
 as a 'thing' or a substantial object. It therefore lies some- 
 where between sensation and perception, and seems to call 
 for a special designation, — perhaps 'infra-percepts' or 'aestha- 
 morphs.' 
 
STUDIES FROM THE PSYCHOLOGICAL LABOR- 
 ATORY OF THE UNIVERSITY 
 OF CALIFORNIA 
 
 XVI. Temporal and Accentual Rhythm 
 
 BY WARNER BROWN 
 
 Reprinted from the Psychologicai, Review, September, 191 1, 
 Vol. XVIII, No. 5. 
 
[Reprinted from The Psychological Review, Vol. XVIII., No. 5, Sept., 1911.] 
 
 STUDIES FROM THE PSYCHOLOGICAL LABOR- 
 ATORY OF THE UNIVERSITY 
 OF CALIFORNIA 
 
 XVI. Temporal and Accentual Rhythm 
 
 BY WARNER BROWN 
 
 Perhaps the only undisputed characteristic of rhythm is 
 the impression of regularity which it occasions. Some hold 
 that this impression arises from the regular recurrence, in 
 time, of certain features of the rhythmic series; others claim 
 that the regularity resides in the structure of the elements 
 composing the series; but in either case some regularity is 
 admitted. A rhythm lacking regularity in its structure and 
 failing in the regular repetition of its elements would be no 
 rhythm. 
 
 I 
 
 The mere repetition of a single undifferentiated movement 
 or sound does not constitute a rhythmic series, properly speak- 
 ing, and yet such a series offers one of the most satisfactory 
 approaches to the more truly rhythmic forms. Movements 
 either with the voice or by tapping, are easily recorded by 
 the kymograph, and may be measured and studied at leisure. 
 On that account a series of movements can be analyzed to 
 better advantage than a series of sounds. 
 
 L 
 
 ^0ttftt0^f^^^r^m^m0^tm0^0^0^0t0^^^0^*^^^^f*m^^^0^^*^^^»^^^^^*^*^^^*^*^^*^*^^^* ^ ^*^*^'^'^^^'^*^*^^*^^'^*^'^^'^ 
 
 ]}J,cxaJIou\, LclJz^ 
 
 Fig. I. 
 
 Fig. I shows a series of regular taps made by the finger. 
 Here regularity is the dominant characteristic. But regu- 
 larity is seen to be of two distinct sorts. Regularity of 
 
 336 . 
 
337 WARNER BROWN 
 
 recurrence appears in the duration of the taps and the interval 
 between them, and over against this is regularity in the 
 performance itself, which manifests itself in the force of the 
 movement. In the record the duration is measured hori- 
 zontally and the force vertically. The degree of regularity 
 
 Table I 
 
 Regular Taps 
 Showing, for each Subject, the Mean Variation, in per cent., from the average of 
 20 taps; with regard to the Force and Duration of the taps. 
 
 Subject Force Duration 
 
 1. Mr. Bates 6.22 3.42 
 
 2. Mr. Detter 9.02 6.44 
 
 3. Mr. Dignan 5.78 2.66 
 
 4. Miss Fisher 11.79 2.40 
 
 5. Mr. Folte 16.90 4.28 
 
 6. Mr. Ham 5.90 3.12 
 
 7. Miss Hendee 10.80 5.69 
 
 8. Mr. Jackson 8.68 3.81 
 
 9. Miss Noteware 6.78 3.03 
 
 10. Mr. Robinson 5.94 3.37 
 
 11. Miss Replogle 15.50 10.00 
 
 12. Mrs. Stanley 13.60 3.31 
 
 13. Miss Umphred 11.90 3.50 
 
 14. Miss Way 10.95 4.38 
 
 15. Mr. Whisman 5.92 4.99 
 
 Average 9.71 4.36 
 
 is found by computing the mean variation from the average 
 of a number of successive movements.^ Table I. shows the 
 variation in force and duration of a series of twenty taps 
 with the index finger on the rubber head of a drum connected 
 with a recording tambour. The subjects^ were requested to 
 tap as regularly as possible in time and force and at a rate 
 of their own choosing. On the whole, averaging the records 
 of the subjects, these taps vary more than twice as much in 
 force as in time. In other words their duration is more than 
 twice as regular as their structural form. For some persons 
 
 ^ The measurements of the movements themselves are of no importance in the 
 present connection, and for the sake of clearness only the variations from their average 
 are mentioned. Throughout this paper the mean variation is expressed in per cent. 
 of the quantity which varies. 
 
 * I am indebted to fifteen of my students in the University of California summer 
 session of 1910 for the records upon which this report is based. 
 
TEMPORAL AND ACCENTUAL RHYTHM 33^ 
 
 the variation in time is more nearly equal to that in force, 
 but in no case is there less variation in force than in time. 
 
 It is evident that this series tends to conserve a regular 
 succession of its elements rather than regularity in their form. 
 But this sacrifice of form to duration occurs in a series which 
 does not profess to have much form, and the further question 
 arises whether the same thing would hold in a truly rhythmic 
 series. 
 
 II 
 
 Fig. 2 shows a series of taps in rhythm. The subjects 
 were instructed to tap in a natural manner in an iambic 
 rhythm, and the explanation was made that this rhythm has 
 the second beat accented or longer than the first, but no 
 
 tflft^.-^u.^>ut Xa^Ak^ 
 
 Fig. 2. 
 
 indication was given as to the relative importance of the 
 temporal or accentual features. Table II. shows for the 
 fifteen subjects the variation in force and duration of the 
 first (short) and second (long) tap, based on the average of 
 a series of ten pairs of taps. The same table shows the 
 variation in total duration of the rhythmic element (the foot, 
 or sum of two successive taps) and of the total force exerted 
 in the element as measured by the sum of the forces exerted 
 on the two parts of it. This table also gives a measure of 
 the structural constancy of the elements in the series both 
 in force and time. This is shown in the column headed 
 "ratio" by the variation, in the two respects, of the ratio 
 between the two parts of the foot when the long or accented 
 part is divided by the short part.^ 
 
 The more complicated performance demanded by this 
 part of the experiment brings out more individual differences 
 
 1 Again only the variations are considered. Tlie actual ratios will be spoken of 
 later on. 
 
339 WARNER BROWN 
 
 Table II 
 
 Iambic Taps 
 Showing for each Subject the Mean Variation in per cent, from the average of 
 10 pairs of taps, with regard to the Force and Duration of the taps. The variation 
 is given for the first or Short tap, for the second or Long tap, for the Sum of the two 
 taps, and for the Ratio found by dividing the short into the long tap. 
 
 Subject 
 
 Short 
 
 I/Ong 
 
 Sum 
 
 Ratio 
 
 F 
 
 D 
 
 F 
 
 D 
 
 F 
 
 D 
 
 F 
 
 D 
 
 I 
 
 2 
 
 3 
 4 
 5 
 6 
 
 7 
 8 
 9 
 
 ID 
 
 11 
 12 
 
 13 
 14 
 IS 
 
 S-7I 
 
 9.91 
 
 9.17 
 
 12.71 
 
 6.21 
 
 16.32 
 
 15.00 
 
 12.98 
 
 5-28 
 
 7.81 
 
 9-83 
 14.60 
 11.40 
 10.05 
 
 9.14 
 
 5-64 
 
 S-25 
 4-S5 
 S-I7 
 6.22 
 4.48 
 S-24 
 6.32 
 4-59 
 2-39 
 4.02 
 4.44 
 340 
 6.08 
 4.48 
 
 1.76 
 6.64 
 6.02 
 9.02 
 S-83 
 5-49 
 7.81 
 8.92 
 6.18 
 S-42 
 10.56 
 6.54 
 
 7-31 
 6.00 
 4.78 
 
 5-94 
 5-92 
 2.60 
 3.56 
 3-43 
 2.66 
 
 6.24 
 6.54 
 S-70 
 4.90 
 6.14 
 2.19 
 4.18 
 
 3-87 
 4.25 
 
 2.98 
 4.98 
 4.02 
 10.07 
 346 
 6.06 
 
 6-43 
 4.10 
 4.11 
 4.68 
 6.36 
 8.31 
 8.31 
 3-53 
 S-04 
 
 3-31 
 4.19 
 
 2.20 
 3-34 
 4-31 
 2.64 
 
 4-54 
 3-79 
 2.86 
 
 2.35 
 5-32 
 2.72 
 3.20 
 
 4-57 
 
 3.82 
 
 5-32 
 14.16 
 11.44 
 11.83 
 II. 41 
 19. II 
 14.50 
 19.38 
 
 6.91 
 
 10.75 
 16.42 
 12.82 
 10.80 
 14.60 
 10.42 
 
 348 
 8.32 
 
 6-35 
 6.04 
 
 5-97 
 4.62 
 5.82 
 9.92 
 4.68 
 6.74 
 4.69 
 5-17 
 
 7.26 
 4.04 
 
 Average. 
 
 10.41 
 
 4.82 
 
 6.55 
 
 4-54 
 
 5-50 
 
 3-54 
 
 12.66 
 
 S-9I 
 
 between the subjects, but in the long run and with very few 
 exceptions the indications of the regular tap series are borne 
 out by the rhythmic series. Whether we consider the short 
 initial stroke, the long accented stroke, or their sum (the whole 
 foot), there is greater variation in force than in time. It 
 should be noted, however, that except for the initial stroke, 
 there is less difference between time and force than in the 
 case of regular taps. Taking the whole foot as a basis for 
 comparion with the regular taps of the first series it is. seen 
 that the introduction of rhythmic form has tended to steady 
 the movements both in time and force, but has reduced 
 the variation in force more than in time. 
 
 The column headed 'ratio' (Table II.) shows the main- 
 tenance of internal structure in the foot or rhythmic unit. 
 On the whole the temporal structure is maintained twice as 
 well as the accentual structure. In neither respect is the 
 internal structure preserved half as well as the uniformity of 
 the rhythmic unit; the ratios vary twice as much as the feet. 
 
TEMPORAL AND ACCENTUAL RHYTHM 
 
 III 
 
 340 
 
 The third part of the experiment (Fig. 3 and Table III.) 
 reports a series of syllables spoken in iambic tetrameter 
 rhythm and recorded by a tambour in the manner indicated in 
 an earlier paper of the writer's.^ The subjects were instructed 
 to speak, in a natural rhythm, the written line: 
 Ta ta, ta ta, ta ta, ta ta; 
 
 JZ ta' ^tr^ -U ^ U "^ y tl tl ^ 
 
 Fig. 3. 
 
 Table III 
 
 Iambic Syllables 
 
 Showing for each subject the Mean Variation in per cent, from the average of 
 ten pairs of syllables from the first foot of the iambic tetrameter line Ta ta, ta ta, 
 ta ta, ta ta; with regard to Force and Duration. The variation is given for the first 
 two syllables separately, for their Sum, and for the Ratio found by dividing the first 
 into the second. 
 
 
 Ta 
 
 
 ta 
 
 
 Sum 
 
 
 Ratio 
 
 Subject 
 
 
 
 
 
 
 
 
 
 F 
 
 D 
 
 F 
 
 D 
 
 F 
 
 D 
 
 F 
 
 D 
 
 I 
 
 10.63 
 
 4.14 
 
 12.56 
 
 3-82 
 
 II. 18 
 
 2.76 
 
 5-94 
 
 9-05 
 
 2 
 
 9.22 
 
 4.29 
 
 8.84 
 
 5-27 
 
 6.23 
 
 3.80 
 
 9-79 
 
 5-45 
 
 3 
 
 36.00 
 
 8.85 
 
 18.38 
 
 13.80 
 
 23-40 
 
 9.22 
 
 22.00 
 
 8.32 
 
 4 
 
 40.30 
 
 10.37 
 
 20.30 
 
 7.00 
 
 22.45 
 
 6-33 
 
 43.60 
 
 11.22 
 
 5 
 
 15-92 
 
 7-34 
 
 11.48 
 
 2.96 
 
 11.82 
 
 2-44 
 
 15.60 
 
 8.58 
 
 6 
 
 24.70 
 
 4.42 
 
 30.80 
 
 8.08 
 
 23-50 
 
 3-94 
 
 27.40 
 
 12.65 
 
 7 
 
 13.80 
 
 11.68 
 
 9.14 
 
 6.26 
 
 4.67 
 
 7.10 
 
 22.10 
 
 8.13 
 
 8 
 
 13.60 
 
 7.04 
 
 12.50 
 
 5-Si 
 
 11.80 
 
 4.90 
 
 12.63 
 
 5.76 
 
 9 
 
 28.00 
 
 6.55 
 
 19.50 
 
 4-77 
 
 17.00 
 
 4.06 
 
 24.70 
 
 8.^2 
 
 ID 
 
 16.77 
 
 7-23 
 
 15-43 
 
 12.51 
 
 15-25 
 
 8.22 
 
 20.50 
 
 15.18 
 
 II 
 
 15-30 
 
 10.90 
 
 16.40 
 
 8.27 
 
 15-50 
 
 4-39 
 
 9.68 
 
 16.65 
 
 12 
 
 13-55 
 
 5-67 
 
 26.84 
 
 7.00 
 
 17.00 
 
 5-57 
 
 22.10 
 
 5.81 
 
 13 
 
 34-9° 
 
 21.40 
 
 37-20 
 
 11.24 
 
 25-30 
 
 5-39 
 
 43-70 
 
 28.30 
 
 14 
 
 17-93 
 
 11.00 
 
 16.82 
 
 6.81 
 
 14.50 
 
 5-97 
 
 22.40 
 
 8.23 
 
 IS 
 
 25.80 
 
 6.63 
 
 11-53 
 
 4-13 
 
 15-43 
 
 4.41 
 
 23.50 
 
 10.76 
 
 Average. 
 
 21.09 
 
 8.50 
 
 17.81 
 
 7.16 
 
 15-67 
 
 5-23 
 
 21.71 
 
 10.84 
 
 like a line of verse, and then to repeat the same line as another 
 verse and so on until stopped. The first foot of each of ten 
 
 1 'Time in English Verse Rhythm,' Archives of Psychol., No. 10, 1908. 
 
341 WARNER iJROPfN 
 
 verses was measured for the record. The force is the height 
 of the consonant, and the duration Is the time from the begin- 
 ning of one consonant to the beginning of the next. Here all 
 the conditions, rhythmic form, motor performance, and experi- 
 mental conditions for making the record, were more com- 
 plicated than in the case of taps. The difficulty of securing 
 an adequate record of the force of the vocal utterance is a 
 particularly serious source of error,^ and yet when we re- 
 member that the syllables to be measured are all made up 
 of the same letters or sounds the data may be considered 
 sufficiently reliable for our purposes. As compared with the 
 iambic taps there is a very large Increase In variability in all 
 directions, and while the larger variation In force may be 
 attributable to instrumental difficulties, the loss of control 
 in time is beyond question. This greater variability indicates 
 that the greater elaborateness of the rhythm or the change 
 in the motor mechanism, or the experimental embarrassments 
 (which were not grave) singly, or together. Interfered with the 
 rhythm in respect both to internal structure and to the rela- 
 tion of the units to one another. 
 
 Yet apart from greater Irregularity, the spoken iambs do 
 not differ materially from those that were tapped, when we 
 consider that the blame for the relatively greater variability 
 in force can properly be laid to instrumental difficulties. In 
 Table II. the difference between time and force was more 
 noticeable in the ratio column than in any other, but in the 
 present case the ratios differ In force only twice as much as in 
 duration, while in the other columns the force varies nearly 
 three times as much as the duration. This is not to be taken 
 as Improvement in the relative regularity of structure as 
 regards force, but again as a peculiarity of the recording 
 device. This device might well record the relative emphasis, 
 i. <?., the ratio of force, within the foot, while it would not 
 report correctly the emphasis in different feet, or over any 
 considerable length of time. 
 
 ^See 'Time in Eng. Verse Rhythm,' p. 22; and compare Bourdon in Uannee 
 psychologique, IV., 1898, p. 370. 
 
TEMPORAL AND ACCENTUAL RHYTHM 
 
 34* 
 
 IV 
 
 In the fourth part of the experiment the subjects were 
 instructed to recite into the recording apparatus in a natural 
 but forceful manner the nursery verses: 
 
 Pease porridge hot, 
 Pease porridge cold, 
 Pease porridge in the pot nine days old. 
 
 Table IV 
 
 Pease Porridge 
 
 Showing for each Subject the Mean Variation in per cent, from an average of lo 
 measurements of the words Pease porridge cold; with regard to Force and Duration. 
 The Variation is shown for each word separately, for the Sum of the three words, and 
 for the Ratio found by dividing the first word into the second. 
 
 
 Pease 
 
 Porridge 
 
 Cold 
 
 Sum 
 
 Ratio 
 
 Subject 
 
 
 
 
 
 
 
 
 
 
 
 F 
 
 D 
 
 F 
 
 D 
 
 F 
 
 D 
 
 F 
 
 D 
 
 F 
 
 D 
 
 I 
 
 15.28 
 
 6.06 
 
 10.86 
 
 4.02 
 
 14.29 
 
 7-74 
 
 9-75 
 
 3-87 
 
 14.68 
 
 3.08 
 
 2 
 
 23.20 
 
 11-55 
 
 29.60 
 
 7.II 
 
 22.40 
 
 6.01 
 
 21.20 
 
 5-71 
 
 32.80 
 
 14.05 
 
 3 
 4 
 5 
 
 12.40 
 
 1 
 
 8.87 
 1 
 
 13.00 
 
 1 
 
 8.28 
 1 
 
 10.17 
 
 1 
 
 6.80 
 
 1 
 
 8.07 
 1 
 
 3-85 
 1 
 
 22.05 
 1 
 
 14.51 
 
 1 
 
 1 
 
 10.90 
 
 1 
 
 8.30 
 
 1 
 
 6.37 
 
 1 
 
 6.74 
 
 1 
 
 12.77 
 
 6 
 
 25-15 
 
 9-77 
 
 37-10 
 
 4.II 
 
 31-85 
 
 7.76 
 
 22.75 
 
 5-54 
 
 46.70 
 
 8.01 
 
 7 
 
 26.60 
 
 7.46 
 
 15.80 
 
 3.66 
 
 15.80 
 
 3-45 
 
 16.30 
 
 3.16 
 
 22.80 
 
 7-25 
 
 8 
 
 17.15 
 
 13-50 
 
 17.90 
 
 7.26 
 
 18.00 
 
 5-54 
 
 14-53 
 
 4.87 
 
 15.20 
 
 17.70 
 
 9 
 
 16.00 
 
 6.00 
 
 16.60 
 
 3.84 
 
 31.70 
 
 8.00 
 
 17.20 
 
 3-84 
 
 15.40 
 
 4-03 
 
 10 
 
 17.88 
 
 6.50 
 
 16.67 
 
 6.24 
 
 40.20 
 
 8.04 
 
 16.93 
 
 3-56 
 
 25.60 
 
 9.85 
 
 II 
 
 20.20 
 
 8.98 
 
 22.20 
 
 II. 18 
 
 25.80 
 
 3-96 
 
 16.60 
 
 3-36 
 
 23.00 
 
 19.30 
 
 12 
 
 11.90 
 
 4.72 
 
 10.70 
 
 1.98 
 
 32.40 
 
 4.04 
 
 7.71 
 
 1-65 
 
 16.65 
 
 4.66 
 
 13 
 
 25.70 
 
 7-05 
 
 28.00 
 
 5. 61 
 
 32.40 
 
 8.92 
 
 15.40 
 
 4-72 
 
 43.00 
 
 10.60 
 
 H 
 
 9-58 
 
 6.02 
 
 13.40 
 
 6.87 
 
 31.20 
 
 12.40 
 
 II. 15 
 
 6.91 
 
 19-25 
 
 9.64 
 
 IS 
 
 24.80 
 
 6.19 
 
 17.60 
 
 3-44 
 
 25.70 
 
 6.81 
 
 13.00 
 
 4-40 
 
 38.60 
 
 6.78 
 
 Av. 
 
 18.91 
 
 8.11 
 
 19.19 
 
 5.86 
 
 25-54 
 
 6.84 
 
 14.66 
 
 4.44 
 
 25-82 
 
 10.16 
 
 This was repeated a number of times. The record, given 
 in Fig. 4 and Table IV., shows the variation in force (height 
 
 \rv^VN/V 
 
 Fig. 4. 
 
 of the initial consonants p, p and c) in the phrase 'Pease 
 porridge cold,' and in time from the beginning of pease to the 
 
 ^ No legible record. 
 
343 WARNER BROWN 
 
 beginning of porridge, from the beginning of porridge to the 
 beginning of cold, and in the duration of the word cold to 
 the end of the final consonant. It also shows the variations 
 in time and force for the whole phrase of three words and in 
 the ratios for the first and second words of the phrase. The 
 variations are based on the average of ten records except that 
 in three cases there were only eight available records. As 
 elsewhere the variations are expressed in per cent, of the 
 quantities involved. 
 
 With regard to either the time or force, the variations in 
 this series are about as large for the separate parts of the 
 foot as in the iambic syllable (ta ta) series. The variation 
 in force exceeds the variation in time in about the same 
 proportion as in that series. But the variations for the foot 
 as a whole fall below those for the iambic syllables. In dura- 
 tion these feet are about as regular as the regular taps of the 
 first series. The ratios present a different aspect, for while 
 in duration they are slightly more regular than the iambic 
 syllables, they are less regular in force. In comparison with 
 the series of iambic syllables the 'Pease porridge' series is 
 more regular in recurrence in regard to both the time and 
 force of the total foot. The 'Pease porridge' series has also a 
 more regular internal structure (ratio) in regard to time but 
 not in regard to force. Loss of control over the relative force 
 of the movements is very evident in even a superficial inspec- 
 tion of the 'Pease porridge' records. The relative force of 
 the two p's often undergoes a complete reversal from verse to 
 verse. The rhythm of this verse is of course irregular or even 
 amorphic but it is of a very distinctly temporal type, giving, 
 all the disturbing factors being considered, very great regu- 
 larity in the matter of recurrence, together with a relatively 
 high degree of regularity in internal structure so far as the 
 time relations are concerned. 
 
 With these concrete examples from which to start we 
 are now in a position to discuss with more understanding 
 the temporal and accentual features in any rhythm. The first 
 point to be observed is that all recurrence is a temporal 
 
TEMPORAL AND ACCENTUAL RHYTHM 344 
 
 matter. A rhythm is temporal in so far as there is any regular 
 return of similar features. But at the same time such a 
 rhythm will also be accentual since there must always be 
 points of emphasis whose return can be marked. At this stage 
 of the discussion the question to be answered is: Which is 
 fundamental to the rhythm; the uniform time of recurrence, 
 or the uniform character of the thing that recurs.^ Assuming 
 a reliable method of measuring both the thing and its rate of 
 recurrence I propose the variability as a test in this question. 
 If the movements or sounds vary in intensity more than 
 in duration or more than the interval separating them, I 
 submit that the rhythm is primarily temporal. No very 
 extended argument seems to be required in support of this 
 view, for regularity is essential to rhythm, and if the regularity 
 is predominantly in the time relations the rhythm may be 
 presumed to have its seat there also. Accent may be a 
 necessary feature but it is not the distinctive feature in the 
 rhythms examined for this study. 
 
 But we can not stop the discussion on the level of mere 
 recurrence; that would be to stop with the whole feet, ignoring 
 their parts. We can not consider the mere intensity and 
 duration of the item which recurs; we must also consider its 
 individual make-up or structural character. This puts us on 
 the second level, that of the structure of the elements com- 
 posing the rhythm. Here we find again intensities and dura- 
 tions, or to speak more accurately, relations of intensity and 
 duration. May it not be that we shall find in one or the other 
 of these relations something that will present greater regular- 
 ity than the mere recurrence of the elements? If so we may 
 look here for the essence of the rhythm. 
 
 On the surface of the returns the ratios which represent 
 these relations appear to be more variable than the periods 
 of recurrence. But as the writer has stated before,^ this 
 view although probably correct can not be taken as final, 
 because the ratios are apparently incommensurable with the 
 actual durations. But we can face this difficulty fairly, and 
 still say that on this second level of structural form, consider- 
 
 1 'Time in English Verse Rhythm,' p. 67. 
 
345 
 
 WARNER BROWN 
 
 ing the ratios independently, it is in the temporal structure 
 and not in the accentual structure that we find the greater 
 regularity. If the fundamental regularity does reside in the 
 arrangement of the parts within the units rather than in the 
 recurrence of these units, it is still to be sought in the arrange- 
 ment of the parts in time. In any event the predominant 
 regularity on either level is a temporal regularity. 
 
 V 
 
 A somewhat different method of attack leads to the same 
 conclusion. If, in Table V., we consider the actual ratios 
 which represent the structure of the elements, we find that 
 the ratios for force of movement are different from the ratios 
 
 Table V 
 
 Ratios 
 Showing for each Subject the average absolute amount of the Ratio found by 
 dividing the first tap or syllable into the second; with regard to Force and Duration. 
 
 
 Iambic Taps 
 
 Ta la 
 
 Pease porridge 
 
 Subject. 
 
 Cf. Table II 
 
 Cf. Table III 
 
 Cf. Table IV 
 
 
 F 
 
 D 
 
 F 
 
 D 
 
 F 
 
 D 
 
 I 
 
 1.22 
 
 1.78 
 
 1.68 
 
 2.18 
 
 1.09 
 
 1. 10 
 
 2 
 
 1.29 
 
 2-45 
 
 1.23 
 
 1.96 
 
 .86 
 
 1. 14 
 
 3 
 
 1.38 
 
 1.71 
 
 1.89 
 
 2.56 
 
 1. 14 
 
 1^33 
 
 4 
 
 I-S7 
 
 2.52 
 
 2.46 
 
 2.56 
 
 
 
 5 
 
 1.28 
 
 1-73 
 
 2.24 
 
 2.93 
 
 
 1. 14 
 
 6 
 
 1.87 
 
 •95 
 
 I-5S 
 
 I.71 
 
 1.02 
 
 1. 14 
 
 7 
 
 1.87 
 
 1.61 
 
 1.92 
 
 2.64 
 
 •98 
 
 1.09 
 
 8 
 
 1.58 
 
 1. 19 
 
 •94 
 
 I.91 
 
 .98 
 
 1. 12 
 
 9 
 
 1.09 
 
 1.79 
 
 2.44 
 
 3.06 
 
 •99 
 
 1.02 
 
 ID 
 
 1.24 
 
 1.07 
 
 1^53 
 
 2.47 
 
 •55 
 
 •94 
 
 II 
 
 1.62 
 
 2.94 
 
 1.05 
 
 2.13 
 
 •93 
 
 1. 16 
 
 12 
 
 1.27 
 
 2.10 
 
 1. 14 
 
 2.00 
 
 .72 
 
 1.05 
 
 13 
 
 1.64 
 
 1.82 
 
 2.82 
 
 2.84 
 
 1. 16 
 
 1.08 
 
 14 
 
 1. 17 
 
 1.96 
 
 1.77 
 
 
 .67 
 
 I-I3 
 
 IS 
 
 1.52 
 
 2.47 
 
 2. II 
 
 3^3i 
 
 .86 
 
 1.49 
 
 Average. 
 
 1.44 
 
 1.87 
 
 1.78 
 
 2.43 
 
 .92 
 
 1. 14 
 
 for duration of movement. In both of the iambic series the 
 time-ratios are larger than the force-ratios. That is to say, 
 the typical iambic structure with the second part outweighing 
 the first part is more adequately or fully carried out in time 
 than in stress. If the essence of the rhythm is on the second 
 level, in the arrangement of the parts within the rhythmic 
 
TEMPORAL AND ACCENTUAL RHYTHM 34^ 
 
 unit, then again the arrangement in time satisfies the require- 
 ments more fully. 
 
 No inferences can be drawn from the absolute ratios of 
 the 'Pease porridge' records because there is no evidence that 
 this was meant by the speakers to be an iambic ryhthm. It 
 has some of the ear-marks of a trochaic rhythm^ and in that case 
 we do not know whether a larger or smaller ratio stands for 
 the typical rhythm. In fact the absolute ratio fails when 
 applied to verse rhythms because of the fact here illustrated 
 that the time-ratio is determined in such cases by the neces- 
 sary time of uttering the words. The second word in this verse 
 appears to be the second element in a trochaic foot; it sounds 
 so to the ear and its initial consonant shows in the record 
 less stress, on the average, than the initial consonant of the 
 first word; and yet it takes longer to say the longer and more 
 complex second word. In verse there are no typical time- 
 ratios and the force-ratios are not easily measured. With this 
 exception the evidence from the absolute ratio furnishes a 
 valuable check upon the evidence from the relative varia- 
 bilities. 
 
 These results are presented with the hope of arousing 
 interest In what appears to me to be a promising method for 
 the analysis of some of the fundamental questions regarding 
 the basis of rhythmic actions and impressions. The results 
 themselves, so far as they go. Indicate as I think, that the 
 time aspects are fundamental and that the accentual features 
 while necessary are not at the root of the phenomena. 
 
 1 Op. cit., p. 55. 
 
STUDIES FROM THE PSYCHOLOGICAL LABOR- 
 ATORY OF THE UNIVERSITY 
 OF CALIFORNIA 
 
 XVII. Some Preferences by Boys and Girls as Shown 
 IN their Choice of Words 
 
 BY M. I. STOCKTON 
 
 Reprinted from the Psychoi,ogicai. Review, September, 1911, 
 Vol. XVIII, No. 5. 
 
[Reprinted from The Psychological Review, Vol. XVIII., No. s, Sept., ign-l 
 
 XVII. Some Preferences by Boys and Girls as Shown 
 IN THEIR Choice of Words 
 
 BY M. I. STOCKTON 
 
 The broader purpose of the experiments reported in this 
 paper was to obtain light upon possible differences in the 
 affective life of children at different ages, and especially upon 
 any differences between boys and girls. The present experi- 
 ments were limited, however, to a study of the difference 
 between boys and girls as shown in their choice between time 
 and space words; between words expressing activity and 
 those expressing passivity; between words relating to dress 
 and those relating to food; between verbs and adjectives. 
 
 These experiments were suggested by the conclusions 
 stated in Mrs. Manchester's paper on 'Unreflective Ideas of 
 Men and Women. '^ The question in her study was whether 
 there is any difference between college men and women in 
 their unreflective ideas. From the results of her experiment 
 she drew the following general conclusions: 
 
 1. The surface ideas of men and women pertain to ob- 
 jects which are familiar and interesting. 
 
 2. The dynamic aspect of objects is more attractive to 
 men, while the static or completed aspect appeals more to 
 women. 
 
 3. Time as a factor enters more largely into the surface 
 ideas of men; space is more often a prominent feature of the 
 surface ideas of women. 
 
 4. Men make a greater use of abstract terms, while 
 women show a preference for concrete and descriptive 
 words. 
 
 The present experiments were carried out in all the 
 grades, above the low second, of the Bay Grammar School, 
 Oakland, Cal. The accompanying table (Table A) gives the 
 age, number and distribution of the pupils participating. 
 
 1 Psychological Review, Vol. 12 (1905), p. 50. 
 
 347 
 
34« 
 
 M. I. STOCKTON 
 
 Method.— It was thought that if a pair of words of equal 
 difficulty and familiarity were offered, one of which was to be 
 selected, although several motives might affect the choice, 
 yet perhaps there might, after elimination and check, be dis- 
 covered some clue to the attractiveness of the ideas themselves. 
 Four lists of twenty pairs of words were selected. In the first 
 list, each pair was composed of a time word and a space word; 
 in the second list, of a word denoting activity and one denoting 
 passivity; in the third list, of one referring to dress and one 
 referring to food; in the fourth list, of a verb and an adjective. 
 
 Table A 
 
 
 Average Number of Pupils Participating in 
 
 Average Age 
 
 Grade 
 
 the Four Sets of Experiments 
 
 
 
 Boys 
 
 Girls 
 
 Boys 
 
 Girls 
 
 B2 
 
 21 
 
 19 
 
 9-3 
 
 8.6 
 
 A3 
 
 20 
 
 17 
 
 lO.I 
 
 9-3 
 
 B3 
 
 14 
 
 17 
 
 10.9 
 
 9-3 
 
 A4 
 
 21 
 
 17 
 
 10.9 
 
 II 
 
 B4 
 
 9 
 
 8 
 
 12.4 
 
 I1.7 
 
 As 
 
 6 
 
 17 
 
 II-3 
 
 12. 1 
 
 Bs 
 
 II 
 
 IS 
 
 13-9 
 
 12. 1 
 
 A6 
 
 18 
 
 12 
 
 13-3 
 
 12.9 
 
 B6 
 
 4 
 
 8 
 
 13-6 
 
 14 
 
 A? 
 
 14 
 
 13 
 
 13-6 
 
 12.9 
 
 By 
 
 6 
 
 9 
 
 H-S 
 
 14 
 
 A8 
 
 4 
 
 6 
 
 14.6 
 
 14-3 
 
 B8 
 
 2 
 
 4 
 
 15.6 
 
 iS-3 
 
 Each pair of words was written, one directly under the 
 other, on a large card which every pupil could see distinctly 
 when the teacher showed it to the class. The cards were 
 numbered so that the words could be presented in order. 
 The words were so written that if a time word was first on 
 one card, a space word was first on the next following; a time 
 word on the third and so on. In this way, any preference 
 due to the position of the word on the card would be offset. 
 Such an order was carefully followed in each of the four lists, 
 as will be seen by glancing at the words on pages 349 and 350. 
 
 Before the cards were presented, paper was distributed to 
 the pupils. They were told to write only one of the two 
 words that appeared on each card. No further information 
 concerning the work was given. With the exception of the 
 
PREFERENCES IN BOYS AND GIRLS 
 
 349 
 
 third set of papers from the eighth grade, the words were 
 written by the pupils of the twelve different classes at the 
 the same hour on each of the four days. 
 
 The lists containing time and space words and words 
 denoting activity and passivity were given on the first day. 
 These have been designated Set I. Set II. was given five weeks 
 later and contained the list of words pertaining to dress and 
 food and the list of verbs and adjectives. Set III. was com- 
 posed of the words of Set I, but the order of the words of 
 each pair was reversed. In this way, a time word that had 
 been first of a pair in Set I., was second of the same pair in 
 Set III. By this double check — that is by alternating within 
 the set itself the class of word that appeared first on each 
 card of the twenty, and by reversing in Set III. the position 
 of each word in its pair as it appeared in Set I. — any influence 
 which might be due to preference for a word merely because 
 it was first or second in its pair would probably in the long run 
 
 Time 
 
 mile 
 year 
 
 List i 
 and Space Words 
 
 little 
 month 
 
 IvIST 2 
 
 Words Denoting Activity and Passivity 
 run romp 
 sit hush 
 
 always 
 under 
 
 
 soon 
 tall 
 
 rest 
 busy 
 
 calm 
 move 
 
 big 
 
 now 
 
 
 down 
 daily 
 
 swim 
 still 
 
 lively 
 softly 
 
 later 
 small 
 
 
 tomorrow 
 thickness 
 
 sleep 
 work 
 
 silent 
 
 hurry 
 
 where 
 when 
 
 
 width 
 quick 
 
 talking 
 listen 
 
 chatter 
 slumber 
 
 hour 
 high 
 
 
 seldom 
 narrow 
 
 quiet 
 throw 
 
 patient 
 speaking 
 
 inch 
 slow 
 
 
 above 
 fast 
 
 dig 
 wait 
 
 climb 
 float 
 
 early 
 large 
 
 
 yesterday 
 outside 
 
 idle " 
 jump 
 
 grow 
 push 
 
 below 
 today 
 
 
 broad 
 until 
 
 play 
 ride 
 
 day 
 night 
 
 then 
 there 
 
 
 time 
 space 
 
 evening 
 morning 
 
 standing 
 chasing 
 
350 
 
 M. I. STOCKTON 
 
 List 
 
 3 
 
 
 List 4 
 
 
 Words Relating to Dress and Food 
 
 Verbs and Adjectives 
 
 
 dress 
 
 collar 
 
 build 
 
 
 sing 
 
 grapes 
 
 cheese 
 
 little 
 
 
 poor 
 
 nut 
 
 banana 
 
 fresh 
 
 
 old 
 
 cap 
 
 ribbon 
 
 threw 
 
 
 buy- 
 
 hat 
 
 velvet 
 
 give 
 
 
 sailed 
 
 pie 
 
 apple 
 
 hot 
 
 
 happy 
 
 berries 
 
 supper 
 
 large 
 
 
 green 
 
 gloves 
 
 cloak 
 
 grow 
 
 
 lived 
 
 coat 
 
 silk 
 
 tell 
 
 
 sold 
 
 calie 
 
 food 
 
 good 
 
 
 glad 
 
 bread 
 
 beef 
 
 rich 
 
 
 long 
 
 sivirt 
 
 lace 
 
 pick 
 
 
 make 
 
 vest 
 
 tailor 
 
 looked 
 
 
 run 
 
 meat 
 
 turkey 
 
 short 
 
 
 red 
 
 fruit 
 
 pudding 
 
 * sweet 
 
 
 kind 
 
 shoes 
 
 necktie 
 
 think 
 
 
 jump 
 
 stockings 
 
 button 
 
 follow 
 
 
 slept 
 
 potatoes 
 
 carrot 
 
 sunny- 
 
 
 small 
 
 butter 
 
 dinner 
 
 fine 
 
 
 merry 
 
 woolen 
 
 shawl 
 
 eat 
 
 
 break 
 
 be compensated. The third set was presented two weeks after 
 the second set. Set IV. contained the words of Set II. in 
 reverse order and was given three weeks later than Set III. 
 
 The pupils of the A second grade because of insufficient 
 power of writing were unsuited to the experiment; so the B 
 second grade is the youngest class employed, and is referred 
 to simply as the second grade. There were so few pupils in 
 the eighth grade that the results of the two divisions together 
 have been given as the eighth grade. The work of the A 
 fourth grade was interrupted on two mornings, so there is 
 only one set of papers for the list of verbs and adjectives and 
 for the list containing words denoting activity and passivity. 
 
 Many difficulties beset one in preparing the lists of words. 
 There were serious limitations placed upon selection by the 
 difference in ability of the various classes. It was necessary 
 that the two words of a pair, fairly intelligible and within 
 the vocabulary of the pupils, should be of the same length 
 
PREFERENCES IN BOYS AND GIRLS 35 ^ 
 
 and of the same degree of difficulty In writing. Although 
 much time was spent In preparing the lists, It Is Impossible 
 to feel that they are entirely satisfactory or beyond criti- 
 cism. 
 
 The results are arranged In Tables I. to IV. which show 
 the percentage of each class of words selected by the boys 
 and girls respectively In the different grades and also the per- 
 centage of first and second words selected In the same lists. 
 The percentages are given for each set of papers obtained from 
 each of the four lists of words and also the average percentage 
 of the two sets. 
 
 In Table V., the total number of each class of words 
 selected by the twelve grades Is given with the corresponding 
 number of first and second words chosen. The percentage 
 selected Is also shown. The more significant figures are those 
 given as percentages of the different classes of words selected. 
 The total number of words is of less value since the proportion 
 of boys and of girls varies in the different grades. 
 
 Plates A to D inclusive give in different form the same 
 results as are given In Tables I. to IV. The ordlnates repre- 
 sent the percentages of preference; the abscissae represent In 
 order the different school grades. The average value of each 
 curve for all twelve grades is also shown In each table by the 
 horizontal lines; e. g., the horizontal line composed of a dot 
 and a dash in Plate A represents the average selection of 
 time words for the twelve grades for the boys, — having a 
 value of 53.9 per cent. Plate E shows the average percentage 
 of the different classes of words and of first and second words 
 for the twelve grades combined. 
 
 Let us consider, first, what conclusions one Is warranted 
 in drawing with regard to the more limited problem of this ex- 
 periment; and later the relation of these results to the larger 
 field will be of Interest. 
 
 The averages of the two sets In Tables I.-IV. are the signifi- 
 cant figures; for any apparent preference due merely to the 
 order of the words is probably eliminated by the alterna- 
 tion and reversal of words explained on page 348. From 
 Table I. and its graphic presentation In Plates A and E, one 
 
352 
 
 M. I. STOCKTON 
 
 Table I 
 
 Percentage of Words Chosen 
 
 Character of the Word 
 
 Second Grade. 
 
 First set 
 
 Third set. . . . , 
 
 Average 
 
 A Third Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 B Third Grade. 
 
 First set. . . . . 
 
 Third set. . . . 
 
 Average 
 
 A Fourth Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 B Fourth Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 A Fifth Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 B Fifth Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 A Si.xth Grade. 
 
 First set .... 
 
 Third set. . . . 
 
 Average 
 
 3 Sixth Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 A Seventh Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 B Seventh Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 Eighth Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 Boys 
 
 Time Space First Second 
 
 54-2 
 49.6 
 
 51.8 
 
 53-7 
 57-4 
 SS-5 
 
 SS4 
 Si.o 
 
 53-2 
 
 56.2 
 54-6 
 SS-4 
 
 50.0 
 50.2 
 SO. I 
 
 54-2 
 50.7 
 52.5 
 
 49.0 
 56.0 
 52.5 
 
 54-7 
 51-4 
 
 S3-0 
 
 SS-o 
 Si-9 
 
 S6.6 
 58.8 
 57-7 
 
 58.8 
 47-9 
 53-3 
 
 60.8 
 
 Si-3 
 56.0 
 
 45.8 
 
 50.4 
 48.2 
 
 46.3 
 42.6 
 
 44-5 
 
 44-6 
 49.0 
 46.8 
 
 43-8 
 45-4 
 44.6 
 
 50.0 
 49.8 
 49.9 
 
 45-8 
 49-3 
 47-5 
 
 SI.O 
 44.0 
 47-S 
 
 45-3 
 48.6 
 47.3 
 
 SI.2 
 45 -o 
 
 48.1 
 
 43-4 
 41.2 
 
 42.3 
 
 41.2 
 
 52.1 
 46.7 
 
 39-2 
 48.7 
 44.0 
 
 43-9 
 42.9 
 
 43-4 
 
 56.3 
 60.4 
 
 58-4 
 
 37-6 
 69.2 
 53-4 
 
 507 
 58.9 
 54-8 
 
 55-5 
 72-3 
 63-9 
 
 34-2 
 62.1 
 
 48.2 
 
 40.0 
 61.4 
 507 
 
 52.2 
 63-9 
 58.1 
 
 537 
 55-0 
 54-4 
 
 44.6 
 64-3 
 54-5 
 
 43-8 
 68.9 
 
 56.4 
 
 53-3 
 68.8 
 61. 1 
 
 56.1 
 57-1 
 56.6 
 
 437 
 39.6 
 41.6 
 
 62.4 
 30.8 
 46.6 
 
 49-3 
 41. 1 
 
 45.2 
 
 44-5 
 27.7 
 36.1 
 
 65.8 
 
 37-9 
 SI.8 
 
 60.0 
 38.6 
 49-3 
 
 47.8 
 36.1 
 41.9 
 
 46-3 
 45 -o 
 45.6 
 
 55-4 
 357 
 45-5 
 
 56.2 
 3I-I 
 43-6 
 
 46.7 
 31.2 
 
 38.9 
 
 Girls 
 
 Time ' Space First Second 
 
 48.6 
 50.4 
 49-5 
 
 53-1 
 53-3 
 53-2 
 
 52.5 
 SI.O 
 
 517 
 
 53-0 
 43-3 
 48.1 
 
 SI.9 
 
 53-4 
 52.6 
 
 50.9 
 52.8 
 51-8 
 
 557 
 55-4 
 55-5 
 
 53-9 
 51-3 
 
 507 
 50.0 
 
 50-3 
 
 537 
 55-9 
 
 54-8 
 
 557 
 69. s 
 62.6 
 
 57-9 
 49.1 
 
 53-5 
 
 514 
 49.6 
 
 50.5 
 
 46.9 
 46.7 
 46.8 
 
 47-5 
 49.0 
 
 48.3 
 
 47.0 
 567 
 51-9 
 
 48.1 
 46.6 
 47.4 
 
 49.1 
 
 47.2 
 
 44-3 
 44.6 
 
 44-5 
 
 SI.2 
 46.1 
 
 487 
 
 49-3 
 50.0 
 
 497 
 
 46-3 
 44.1 
 
 45-2 
 
 44-3 
 30.5 
 37-4 
 
 42.1 
 50.9 
 46.5 
 
 50.5 
 62.1 
 
 56.3 
 
 62.7 
 64.2 
 634 
 
 37-2 
 69.2 
 53-2 
 
 SI.O 
 53-9 
 
 524 
 
 33-1 
 46.6 
 
 39-8 
 
 42.9 
 47.2 
 SO. I 
 
 44-3 
 59-3 
 SI.8 
 
 51-2 
 
 707 
 60.9 
 
 67.8 
 
 74-3 
 71. 1 
 
 48.9 
 67.2 
 58.1 
 
 52.2 
 587 
 55-5 
 
 36.7 
 80.0 
 
 58.3 
 
 49-5 
 37-9 
 437 
 
 37-3 
 35-8 
 36.6 
 
 62.8 
 30.8 
 46.8 
 
 49.0 
 46.1 
 47.6 
 
 66.9 
 
 534 
 60.2 
 
 57-1 
 42.8 
 
 49-9 
 
 557 
 40.7 
 48.2 
 
 29-3 
 39-1 
 
 32.2 
 
 257 
 28.9 
 
 SI. I 
 32.8 
 41.9 
 
 47.8 
 41.2 
 44-5 
 
 63-3 
 20.0 
 417 
 
PREFERENCES IN BOYS AND GIRLS 
 
 353 
 
 I 
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 *? 
 
 A 
 
 A 
 
 A^ 
 
 7-V- 
 
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 ^oys: -r/Afe 
 
 G/fiUSi T/**» 
 
 
 V 
 
 K 
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 A 
 
 A \ 
 
 IX. 
 
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 <s/yfi^ .' ^s»<tClS 
 
 BOKS: g»>IC4t 
 
 £ AS £3 /4^ .<94» /*r iS5- ^<5 ^<5 >«r XT 3 
 
 Plate A. Choice between time-words and space-words, selected by boys and 
 girls respectively. The ordinates indicate in per cent, the amount of preference 
 shown for each of the two groups of words; the abscissae, the school-grades. (From 
 Table I.) 
 
354 
 
 M. I. STOCKTON 
 
 Table II 
 
 Percentage of Words Chosen 
 
 Character of the Word 
 
 Second Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 A Third Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 B Third Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 A Fourth Grade. 
 
 First set 
 
 B Fourth Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 A Fifth Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 B Fifth Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 A Sixth Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 B Sixth Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 A Seventh Grade 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 B Seventh Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 Eighth Grade. 
 
 First set 
 
 Third set. . . . 
 
 Average 
 
 
 Boys 
 
 
 Girls 
 
 Ac- 
 tivity 
 
 Pass- 
 ivity 
 
 First 
 
 Second 
 
 Ac- 
 tivity 
 
 Pass- 
 ivity 
 
 First 
 
 Second 
 
 49- S 
 46.8 
 48.2 
 
 50.5 
 53-2 
 SI.8 
 
 45-4 
 41.6 
 
 43-5 
 
 54-6 
 
 58.4 
 
 56.5 
 
 53-5 
 53-2 
 53-4 
 
 46-5 
 46.8 
 46.6 
 
 48-5 
 54-8 
 SI.6 
 
 Si-S 
 45-2 
 48-4 
 
 51-6 
 51.8 
 Si-7 
 
 48.4 
 48.2 
 48-3 
 
 60.5 
 
 51-5 
 56.0 
 
 39-5 
 48.5 
 44.0 
 
 50.0 
 50-5 
 
 48.9 
 50.0 
 
 49-5 
 
 57-1 
 63-4 
 60.3 
 
 42-9 
 36.6 
 
 39-7 
 
 54-5 
 41.6 
 48.0 
 
 4S-S 
 58.4 
 52.0 
 
 447 
 63-9 
 54-3 
 
 55-3 
 36.1 
 457 
 
 54-2 
 49.1 
 51-6 
 
 45-8 
 50.9 
 48.4 
 
 45-1 
 
 58.3 
 517 
 
 54-9 
 41.7 
 
 48.3 
 
 50.9 
 
 49.1 
 
 52.9 
 
 47.1 
 
 46.0 
 
 54-0 
 
 SI.O 
 
 49.0 
 
 48.3 
 Si-3 
 49.8 
 
 517 
 48.7 
 50.2 
 
 60.6 
 67.4 
 64.0 
 
 39-4 
 32.6 
 36.0 
 
 43-1 
 36.1 
 
 39-6 
 
 56.9 
 63-9 
 60.4 
 
 39-4 
 57-9 
 48.6 
 
 60.6 
 42.1 
 51-4 
 
 45-4 
 53-9 
 49.6 
 
 54-6 
 46.1 
 
 S0.4 
 
 36.2 
 61.8 
 49.0 
 
 63.8 
 38.2 
 Si.o 
 
 SO. I 
 48-S 
 49-3 
 
 49-9 
 51-S 
 50.7 
 
 51.2 
 51-5 
 Si-4 
 
 48.8 
 48.5 
 48.6 
 
 49-S 
 58.9 
 54-2 
 
 So-S 
 41. 1 
 
 45-8 
 
 46.5 
 50.3 
 48.4 
 
 53-5 
 497 
 51.6 
 
 48.1 
 49.2 
 48.6 
 
 Si-9 
 
 50.8 
 
 51-4 
 
 47-5 
 53-1 
 50.3 
 
 52.5 
 46.9 
 
 49-7 
 
 54-5 
 50.6 
 
 S2-S 
 
 45-S 
 49-4 
 47-S 
 
 47-S 
 70.1 
 58.8 
 
 52.5 
 29.9 
 41.2 
 
 51-2 
 48.8 
 50.0 
 
 48.8 
 
 SI-2 
 50.0 
 
 53-5 
 42.2 
 47.8 
 
 46-5 
 57-8 
 
 52.2 
 
 56.2 
 54-5 
 
 SS-4 
 
 43-8 
 
 4S-S 
 44.6 
 
 71.2 
 
 48.S 
 59-8 
 
 28.8 
 
 51-5 
 40.2 
 
 47.1 
 43-6 
 45-4 
 
 52-9 
 56.4 
 54-6 
 
 72.8 
 73-6 
 
 73-2 
 
 27.2 
 26.4 
 26.8 
 
 517 
 
 57.2 
 
 54-5 
 
 48.3 
 42.8 
 
 45-5 
 
 52.3 
 597 
 56.0 
 
 477 
 40-3 
 44.0 
 
 50-4 
 45-6 
 48.0 
 
 49-6 
 54-4 
 52-0 
 
 56.1 
 56-9 
 56.5 
 
 43-9 
 43-1 
 43-5 
 
 47-5 
 49.1 
 
 48.3 
 
 52.5 
 50.9 
 517 
 
 52.5 
 70.2 
 61.4 
 
 47-S 
 29.8 
 38.6 
 
 44-3 
 43-5 
 43-9 
 
 557 
 56-S 
 56-1 
 
 52-8 
 57-1 
 54-9 
 
 47.2 
 42.9 
 45-1 
 
 52.1 
 46.4 
 49-3 
 
 47-9 
 53-6 
 50.7 
 
 49.6 
 
 737 
 61.6 
 
 50.4 
 26.3 
 38-4 
 
 48.3 
 
 52.2 
 
 50-3 
 
 51-7 
 47-8 
 49-7 
 
 39-2 
 84.1 
 61.6 
 
 60.8 
 15-9 
 
 38.4 
 
PREFERENCES IN BOYS AND GIRLS 
 
 355 
 
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 Si* I • 
 
 V 
 
 ' ; V V/ \ ; \ \ / »' / 
 
 .-*'9/. 
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 \ I 
 
 \ I 
 
 
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 £ /i3 £3 A-9 £-9^ yiS Sff y^(5 JB<S A7 S7 3 
 Plate B. Choice between words denoting activity and passivity by boys and 
 girls respectively. The ordinates indicate in per cent, the preference shown for each 
 of the two groups of words, the abscissae, the school-grades. (From Table II.) 
 
 may conclude that a noticeable predominance of time interest 
 is shown by both boys and girls. There is a slightly greater 
 predominance of time interest among the boys than among 
 the girls. In these same sets of time and space words, there 
 is a predominance of first words in ten grades among the 
 boys and in eleven grades among the girls. 
 
356 
 
 M. I. STOCKTON 
 
 Table III 
 
 Percentage of Words Chosen 
 
 Character of Word Chosen 
 
 Second Grade. 
 
 Second set. . 
 
 Fourth set. . 
 
 Average. . . . 
 A Third Grade. 
 
 Second set. . 
 
 Fourth set. . 
 
 Average. . . . 
 B Third Grade. 
 
 Second set. . 
 
 Fourth set. . 
 
 Average. . . . 
 A Fourth Grade. 
 
 Second set. . 
 
 Fourth set. . 
 
 Average. . . . 
 B Fourth Grade. 
 
 Second set. . 
 
 Fourth set. . 
 
 Average. . . . 
 A Fifth Grade. 
 
 Second set. . 
 
 Fourth set. . 
 
 Average. . . . 
 B Fifth Grade. 
 
 Second set. . 
 
 Fourth set. . 
 
 Average. . . . 
 A Sixth Grade. 
 
 Second set. . 
 
 Fourth set. . 
 
 Average. . . . 
 B Sixth Grade. 
 
 Second set. . 
 
 Fourth set. . 
 
 Average. . . . 
 A Seventh Grade. 
 
 Second set. . 
 
 Fourth set. . 
 
 Average. . . . 
 B Seventh Grade 
 
 Second set. . 
 
 Fourth set. . 
 
 Average. . . . 
 Eighth Grade. 
 
 Second set. . 
 
 Fourth set. . 
 
 Average. . . . 
 
 Boys 
 
 Girls 
 
 Dress 
 
 Food 
 
 First 
 
 Second 
 
 Dress 
 
 Food 
 
 First 
 
 Second 
 
 50.7 
 48.S 
 49.6 
 
 49-3 
 51-5 
 S0.4 
 
 60.3 
 39-6 
 49.9 
 
 397 
 60.4 
 SO. I 
 
 S0.8 
 
 37-3 
 44.1 
 
 49.2 
 62.7 
 55-9 
 
 56.1 
 517 
 53-9 
 
 43-9 
 48.3 
 46.1 
 
 49-9 
 497 
 49.8 
 
 SO. I 
 SO-3 
 
 50.2 
 
 41-3 
 72.6 
 
 56.9 
 
 587 
 27.4 
 
 43-1 
 
 58.1 
 50.8 
 
 54-5 
 
 41.9 
 49.2 
 45-5 
 
 527 
 72.1 
 62.4 
 
 47-3 
 27.9 
 
 37-6 
 
 41. 1 
 
 SS-4 
 48.3 
 
 58.9 
 44.6 
 
 S17 
 
 53-3 
 64.8 
 
 59-1 
 
 46.7 
 35-2 
 40.9 
 
 41. 1 
 
 44-5 
 42.8 
 
 58.9 
 55-5 
 57-2 
 
 53-5 
 57-4 
 
 ss-s 
 
 46.S 
 42.6 
 44-S 
 
 40.0 
 42.9 
 4I-S 
 
 60.0 
 57-1 
 
 58.5 
 
 S9-0 
 57-1 
 S8.i 
 
 41.0 
 
 42.9 
 41.9 
 
 39-6 
 43-1 
 41.4 
 
 60.4 
 
 56.9 
 58.6 
 
 46.4 
 
 57-3 
 51.8 
 
 53-6 
 42.7 
 48.2 
 
 497 
 45-5 
 47.6 
 
 S0.3 
 54-5 
 52.4 
 
 61.3 
 57-1 
 S9-2 
 
 387 
 42.9 
 40.8 
 
 45-0 
 47.6 
 
 46.3 
 
 55-0 
 52.4 
 537 
 
 42.9 
 
 59-5 
 SI.2 
 
 57-1 
 40.S 
 48.8 
 
 42.2 
 41.7 
 41.9 
 
 57.8 
 58.3 
 S8.i 
 
 51-9 
 44.8 
 48.4 
 
 48.1 
 SS.2 
 SI.6 
 
 49.1 
 49-4 
 49-3 
 
 50.9 
 50.6 
 
 507 
 
 52.3 
 57-9 
 55-1 
 
 477 
 42.1 
 
 44-9 
 
 56.4 
 31-5 
 43-9 
 
 43-6 
 68.5 
 56.1 
 
 66.1 
 53-2 
 59-6 
 
 33-9 
 46.8 
 40.4 
 
 44.8 
 44.1 
 44-5 
 
 SS.2 
 55-9 
 55-5 
 
 51-3 
 S8.1 
 
 547 
 
 487 
 41.9 
 
 45-3 
 
 38.S 
 28.9 
 
 337 
 
 61.5 
 71. 1 
 
 66.3 
 
 63.6 
 66.1 
 64.8 
 
 36.4 
 33-9 
 35-2 
 
 SS-9 
 
 52.9 
 54-4 
 
 44.1 
 47.1 
 45.6 
 
 67.9 
 67.1 
 67.5 
 
 32.1 
 32-9 
 32.5 
 
 30.0 
 20.0 
 25.0 
 
 70.0 
 80.0 
 7S-0 
 
 57-5 
 65.0 
 61.3 
 
 42.5 
 35-0 
 387 
 
 44.1 
 45 -o 
 44-5 
 
 55-9 
 5S-0 
 55-5 
 
 77-4 
 67.S 
 72.S 
 
 22.6 
 32.5 
 27-5 
 
 37-6 
 18.6 
 28.1 
 
 62.4 
 81.4 
 71.9 
 
 56.2 
 53-6 
 S4-9 
 
 43-8 
 46.4 
 
 45-1 
 
 377 
 24.1 
 
 30-9 
 
 62.3 
 
 75-9 
 69.1 
 
 45-8 
 55-5 
 50.6 
 
 54-2 
 44-5 
 49-4 
 
 52.5 
 34-2 
 43-4 
 
 47-5 
 65.8 
 56.6 
 
 50.8 
 
 42.S 
 46.6 
 
 49.2 
 57-5 
 53-4 
 
 53-6 
 40.6 
 47.1 
 
 46.4 
 59-4 
 52.9 
 
 50.3 
 57-3 
 53-8 
 
 497 
 427 
 46.2 
 
 4S-8 
 38.8 
 42-3 
 
 54-2 
 61.2 
 577 
 
 57-5 
 71.2 
 64.4 
 
 42.5 
 28.8 
 
 35-6 
 
 47.1 
 45-9 
 46-5 
 
 52-9 
 54-1 
 53-5 
 
 53-8 
 587 
 56.3 
 
 46.2 
 413 
 437 
 
PREFERENCES IN BOYS AND GIRLS 
 
 357 
 
 1 \ 
 
 I \ 
 
 ad 
 
 ( 
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 v 
 
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 <e ^43 ,<a5 w-^ ^^ yfS -3^ ^^ -^-^ A7 /57' S 
 
 Plate C. Choice between words denoting food and dress, by boys and girls 
 respectively. The ordinates indicate in per cent, the amount of preference shown for 
 each of the two groups of words; the abscissae, the school-grades. (From Table III.) 
 
358 
 
 M. I. STOCKTON 
 
 Table IV 
 
 Percentage of Words Chosen 
 
 Character of Word Chosen 
 
 Second Grade. 
 
 Second set. . , 
 
 Fourth set. . , 
 
 Average . . . . , 
 A Third Grade. 
 
 Second set. . 
 
 Fourth set. . 
 
 Average . . . . , 
 B Third Grade. 
 
 Second set. . , 
 
 Fourth set. . , 
 
 Average 
 
 A Fourth Grade. 
 
 Fourth set. . , 
 B Fourth Grade. 
 
 Second set. . 
 
 Fourth set. . 
 
 Average .... 
 A Fifth Grade. 
 
 Second set. . 
 
 Fourth set. . . 
 
 Average .... 
 B Fifth Grade. 
 
 Second set. . 
 
 Fourth set. . 
 
 Average .... 
 A Sixth Grade. 
 
 Second set. . 
 
 Fourth set. . 
 
 Average. ... 
 B Sixth Grade. 
 
 Second set. . 
 
 Fourth set. . 
 
 Average. . . . 
 A Seventh Grade. 
 
 Second set. . 
 
 Fourth set. . 
 
 Average. . . . 
 B Seventh Grade. 
 
 Second set . . 
 
 Fourth set. . 
 
 Average. ... 
 Eighth Grade. 
 
 Second set. . , 
 
 Fourth set. . , 
 
 Average .... 
 
 Boys 
 
 Verbs 
 
 Adjec- 
 tives 
 
 First 
 
 Second 
 
 45-8 
 45-3 
 4S-S 
 
 54.2 
 547 
 S4-S 
 
 587 
 40.8 
 
 497 
 
 41-3 
 59-3 
 S0.3 
 
 43-1 
 45.6 
 
 44-4 
 
 56.9 
 54-4 
 5S-6 
 
 55-4 
 69.7 
 62.5 
 
 44.6 
 30.3 
 37-5 
 
 437 
 46.2 
 44.9 
 
 56.3 
 53-8 
 55-1 
 
 66.9 
 69.6 
 68.3 
 
 33-1 
 30.4 
 317 
 
 447 
 
 55-3 
 
 51.9 
 
 48.1 
 
 44.0 
 43-8 
 43-9 
 
 56.0 
 56.2 
 56.1 
 
 61.0 
 67.2 
 64.1 
 
 39-0 
 32.8 
 
 35-9 
 
 37-2 
 47-3 
 42.3 
 
 62.8 
 527 
 577 
 
 50.0 
 48.4 
 49.2 
 
 50.0 
 51.6 
 50.8 
 
 38.8 
 
 427 
 40.7 
 
 61.2 
 57-3 
 59-3 
 
 62.7 
 50-4 
 56.5 
 
 37-3 
 49.6 
 
 43-5 
 
 46.9 
 42.9 
 44-9 
 
 53-1 
 57-1 
 55-1 
 
 65.2 
 69.6 
 67.4 
 
 34-8 
 
 30.4 
 32.6 
 
 41.9 
 
 40. s 
 
 41.2 
 
 S8.i 
 
 59-5 
 58.8 
 
 67.6 
 50.6 
 59-1 
 
 32.4 
 49-4 
 40.9 
 
 41.9 
 39-8 
 40.8 
 
 58.1 
 60.2 
 59-2 
 
 61. 1 
 
 59-8 
 60.5 
 
 38.9 
 40.2 
 
 39-5 
 
 4S-8 
 49.2 
 
 47-5 
 
 54-2 
 50.8 
 52.5 
 
 67-5 
 44.2 
 
 55-8 
 
 32.5 
 55-8 
 44.2 
 
 35-9 
 43-1 
 
 39-5 
 
 64.1 
 
 56.9 
 60.5 
 
 57-5 
 70.9 
 64.2 
 
 42-5 
 29.1 
 
 35-8 
 
 Girls 
 
 Verbs Adjec- pi^st Second 
 tives 
 
 46.8 
 
 36.4 
 41.6 
 
 43-4 
 46.6 
 
 45 -o 
 
 42.2 
 42.1 
 42.2 
 
 43-3 
 
 42.5 
 38.5 
 40.5 
 
 41.2 
 43-3 
 42-3 
 
 40.7 
 
 36.5 
 38.6 
 
 43-3 
 517 
 47-5 
 
 45-6 
 41.9 
 
 437 
 
 40.7 
 38.9 
 39-8 
 
 48.1 
 41. 1 
 44.6 
 
 41.2 
 
 43-9 
 42.5 
 
 53-2 
 63.6 
 
 58.4 
 
 56.6 
 53-4 
 55-0 
 
 57-8 
 57-9 
 57-8 
 
 567 
 
 57-5 
 61.S 
 59-5 
 
 58.8 
 567 
 577 
 
 59-3 
 63-5 
 61.4 
 
 567 
 48.3 
 52.5 
 
 54-4 
 58.1 
 56.3 
 
 59-3 
 61. 1 
 60.2 
 
 51-9 
 58.9 
 
 SS-4 
 
 58.8 
 56.1 
 
 57-5 
 
 59-5 
 54-4 
 56.9 
 
 62.4 
 80.1 
 71-3 
 
 56.9 
 64.1 
 
 60.5 
 
 56.3 
 
 49.1 
 63.2 
 56.2 
 
 60.8 
 62.4 
 61.6 
 
 577 
 55-6 
 56.6 
 
 58-9 
 57-5 
 58.2 
 
 79-4 
 70.6 
 
 75 -o 
 
 45.6 
 
 54-5 
 50.1 
 
 55-8 
 58.9 
 57-4 
 
 54-3 
 56.7 
 55-5 
 
 40-5 
 45.6 
 
 43-1 
 
 37-6 
 19.9 
 
 28.7 
 
 43-1 
 35-9 
 39-5 
 
 437 
 
 50.9 
 36.8 
 43-8 
 
 39-2 
 37-6 
 38.4 
 
 42.3 
 44.4 
 
 43-4 
 
 41. 1 
 42.5 
 41.8 
 
 20.6 
 29.4 
 
 25.0 
 
 54-4 
 
 45-5 
 49-9 
 
 44.2 
 41. 1 
 42.6 
 
 457 
 43-3 
 44-5 
 
PREFERENCES IN BOYS AND GIRLS 
 
 359 
 
 
 .. A^-^.—--' 
 
 /\ 
 
 /I 
 
 I .soys:^u>s/£cr/k'£ 
 
 A 
 
 iV / 
 
 11 
 
 U 
 
 ••A-''-"-~X 
 
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 A 
 
 
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 f 
 
 .aoxs: i^^eRO 
 
 & y\3 S3 X'5' S0 >W .S^ >»<5 ^tf /\7 ST 3 
 
 Plate D. Choice between verbs and adjectives by boys and girls respectively. 
 The ordinates indicate in per cent, the amount of preference shown for each of the two 
 groups of words; the abscissae, the school-grades. (From Table IV.) 
 
 Table 11. and Plates B and E show a slight preference 
 among the boys for words denoting activity and not quite so 
 great a preference among the girls for words denoting pas- 
 sivity. The preference for first words is shown in nine grades 
 among the boys and in ten grades among the girls. 
 
 Table III. and Plates C and E show a preference for words 
 
36o 
 
 M. I. STOCKTON 
 
 pertaining to food among both boys and girls. The preference 
 is more marked among the boys and is shown for all the 
 grades (Plate C); whereas it is shown in ten of the grades 
 among the girls. The greatest difference in the choice of 
 contrasting words is shown here in the result for the boys 
 of the B6 and Ay grades. There is a predominance here of 
 first words in nine grades among the boys and in all grades 
 among the girls. 
 
 Table V 
 
 Showing the total number and percentage of each class of words chosen and also 
 the total number and percentage of first and second words chosen. 
 
 
 Time 
 
 Space 
 
 First Second 
 
 Activ. 
 
 Passiv. 
 
 First 
 
 Second 
 
 Boys 
 
 Girls 
 
 3206 
 
 53-9 
 3458 
 
 52.8 
 
 2743 
 
 46.1 
 3084 
 
 47.2 
 
 3233 
 
 54-3 
 3562 
 
 54-5 
 
 2716 
 
 457 
 2980 
 
 45-5 
 
 2812 
 
 5I-I 
 3039 
 49.1 
 
 2688 
 
 48.9 
 3153 
 
 50.9 
 
 2976 
 
 54-1 
 3310 
 
 53-5 
 
 2524 
 
 45-9 
 
 2882 
 46.5 
 
 
 Dress 
 
 Food 
 
 First 
 
 Second 
 
 Verb 
 
 Adj. 
 
 First 
 
 Second 
 
 Boys 
 
 Girls 
 
 2467 
 
 41.9 
 2942 
 
 45-4 
 
 3409 
 
 58.1 
 3544 
 
 54-6 
 
 3336 
 
 56.7 
 3666 
 
 56.6 
 
 2540 
 
 43-3 
 2820 
 
 43-4 
 
 2408 
 
 437 
 2584 
 
 42-5 
 
 3100 
 
 56.3 
 3492 
 
 57-5 
 
 3267 
 
 59-3 
 3614 
 
 S9-S 
 
 2241 
 
 40.7 
 2462 
 
 40-5 
 
 Table IV. and Plates D and E show a predominance of 
 adjectives in all the grades among both boys and girls; here 
 the preference is greater among the girls. There is a pre- 
 dominance of first words among the girls in all grades and 
 among the boys in ten grades. 
 
 Although Mrs. Manchester's work was upon men and 
 women, nevertheless a comparison of these results with hers 
 is interesting. The element of time was more noticeable 
 among the ideas of men and that of space among the ideas 
 of women. These boys and girls alike show a preference for 
 time ideas — the preference being slightly greater among the 
 boys. The idea of activity was characteristic of the men's 
 lists while that of inactivity appeared in the women's lists. 
 The boys show, on the average, a preference for words denot- 
 ing activity, although even among them there is in six of the 
 twelve grades a slight predominance of words denoting pas- 
 sivity. Among the girls there is a noticeable preference for 
 words denoting passivity. The men were slightly in advance 
 
PREFERENCES IN BOYS AND GIRLS 
 
 361 
 
 $' 
 
 [l 
 
 IlL 
 
 ii 
 iii! 
 
 VI K ? 
 
 5^ S t^ 
 
 i! i! 
 
 hi 
 
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 I i! 
 
 i! I! 
 il iill 
 
 ILp. 
 HI 
 
 
 Plate E. Choice between the various groups of words, and the choice between 
 first and second words when the several groups were offered. (From Table V.) 
 
 of the women with reference to food; whereas the women 
 exceeded the men in the class referring to wearing apparel. 
 In this experiment, both boys and girls show a marked prefer- 
 ence for words denoting food; the preference is stronger 
 among the boys. The men led in the number of verbs 
 written and the women in the number of adjectives. Both 
 boys and girls show a great preference for adjectives. 
 
362 M. I. STOCKTON 
 
 The larger problem concerning the difference at various 
 ages in the affective life of boys and girls may be considered 
 in two aspects: (i) What may be inferred from the results of 
 this experiment concerning the problem? (2) How are such 
 inferences related to the conclusions of other investigators? 
 
 Considering now the first of these, Plates A to D suggest 
 a tendency toward an increase of preference with age. That 
 this tendency might be more carefully studied, Table VI. was 
 prepared. This table shows in percentages the change of 
 preference based on the different classes of ideas, with age, 
 on the part of the boys and the girls. Table VII. shows the 
 change of preference based on the position of the words, with 
 age, on the part of the boys and the girls. Plate F gives in 
 graphic form the data of Table VI.; and Plate G, the data 
 of Table VII. 
 
 Comparing the two plates (F and G), one sees that the 
 preference based upon the position of the words is more pro- 
 nounced than the preference based upon ideas. This is 
 certainly contrary to the expectations of the writer at the 
 beginning of the experiments. Although one is not surprised 
 to find the pupils in the second and third grades showing a 
 preference for words merely according to their position, one 
 does not look for such purely superficial preference in the 
 upper grades. One's general observation that children grow 
 more thoughtful after nine or ten years of age is upheld by 
 such studies as Mrs. Mary Sheldon Barnes' and Miss Vos- 
 trovsky's. Mrs. Barnes^ has shown that the ability of both 
 boys and girls to make legitimate and critical inferences from 
 an historical incident increases after eight years of age. The 
 increase at first is gradual, then more rapid. Miss Vostrov- 
 sky2 found an increase with age in definite answers to the 
 question, "Why did you select your last book?" She also 
 found an increase of disbelief in superstitions with age.^ 
 
 Comparing Plates F and G more closely, one sees that 
 among the girls there are five grades in which the curve for 
 preference based upon ideas rises above 10 per cent.; in four 
 
 * 'Studies in Historical Method,' Boston, 1896, p. 68. 
 
 * 'Study of Children's Superstitions,' Barnes' 'Studies in Education,' Vol. I, p. 123. 
 
 ''Children's Reading Tastes,' Pedagogical Seminary, Vol. 6, p. 523. 
 
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 Plate F. Varying degree of preference arising from difference of the ideas 
 conveyed by the words offered. The ordinates indicate the relative strength of such 
 preference; the abscissae, the school-grades. (From Table VI.) 
 
PREFERENCES IN BOYS AND GIRLS 
 
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366 
 
 M. I. STOCKTON 
 
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 3<7 . 
 
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 % Ai BS Af af A*^ Be A6 B€ A7 B7 8 
 Plate G. Varying degree of preference arising from mere position of the word 
 in its pair. The ordinates indicate the relative strength of such preference; the ab- 
 scissa, the school-grades. (From Table VII). 
 
PREFERENCES IN BOYS AND GIRLS 3^7 
 
 of these grades the curve for preference based upon the order 
 of words is below lo per cent. There are six grades, in which 
 the curve for preference based upon the order of words is 
 above lo per cent.; in five of these grades the preference 
 based upon ideas is below lo per cent. Among the boys, 
 there are six grades in which the curve for preference based 
 upon ideas rises above lo per cent.; in four of these grades, the 
 curve for preference based upon the order of the words rises 
 above lo per cent. There are eight grades in which the curve 
 for preference based upon the order of the words rises above 
 lo per cent.; in five of these grades, the curve for preference 
 based upon ideas rises above ten per cent. 
 
 Table VIII 
 
 Showing the Degree of Intensity of Preference, in per cent. Computed from 
 Table V which Shows the Average Preference for the Twelve Grades 
 Time and space words. 
 
 boys 7.8 in favor of time. 
 
 girls 5.6 in favor of time. 
 Words denoting activity and passivity. 
 
 boys 2.2 in favor of activity. 
 
 girls 1.8 in favor of passivity. 
 Words relating to dress and to food. 
 
 boys 16.2 in favor of food. 
 
 girls 9.2 in favor of food. 
 Verbs and adjectives. 
 
 boys 12.6 in favor of adjectives. 
 
 girls 15. in favor of adjectives. 
 • Average preference for first words in all classes of words. 
 
 boys 12.2 in favor of first words. 
 
 girls 12.05 ^n favor of first words. 
 
 With the double check in the arrangement of the words, 
 described on page 348, one would expect that where the 
 preference for first words is pronounced, there would be a 
 diminished preference for either class of ideas, and vice versa. 
 And yet, to show that the preference for first words may be 
 most apparent in connection with a preference for the idea 
 conveyed by the word, a copy of two lists of words with actual 
 elections is submitted. The A sixth grade boys' lists for words 
 relating to dress and food are selected because Table III 
 shows a marked preference for words relating to food and 
 also for first words. 
 
368 
 
 M. I. STOCKTON 
 
 As was stated previously, these two sets were written 
 some five weeks apart. The number after each word Indicates 
 the number of boys who wrote that word. First words are 
 selected 215 times in the * second set'; of these, 125 relate 
 to food, 90 relate to dress. In the 'fourth set,' first words are 
 selected 238 times; of these, 157 relate to food, 81 relate to 
 dress. 
 
 Table B 
 
 A-SixTH Grade: 
 
 Boys' Elections of 
 
 Words Relating to Dress 
 
 AND Food 
 
 Second Set 
 
 Fourth Set 
 
 Second Set 
 
 Fourth Set 
 
 dress 
 
 13 
 
 grapes 
 
 16 
 
 collar 
 
 8 
 
 cheese 15 
 
 grapes 
 
 4 
 
 dress 
 
 2 
 
 cheese 
 
 9 
 
 collar 3 
 
 nut 
 
 12 
 
 cap 
 
 II 
 
 banana 
 
 12 
 
 ribbon 6 
 
 cap 
 
 S 
 
 nut 
 
 7 
 
 ribbon 
 
 5 
 
 banana 12 
 
 hat 
 
 II 
 
 pie 
 
 14 
 
 velvet 
 
 7 
 
 apple 17 
 
 pie 
 
 6 
 
 hat 
 
 4 
 
 apple 
 
 10 
 
 velvet I 
 
 berries 
 
 12 
 
 gloves 
 
 10 
 
 supper 
 
 14 
 
 cloak 6 
 
 gloves 
 
 5 
 
 berries 
 
 8 
 
 cloak 
 
 3 
 
 supper 12 
 
 coat 
 
 II 
 
 cake 
 
 16 
 
 silk 
 
 9 
 
 food 14 
 
 cake 
 
 6 
 
 coat 
 
 2 
 
 food 
 
 8 
 
 silk 4 
 
 bread 
 
 12 
 
 skirt 
 
 9 
 
 beef 
 
 12 
 
 lace 7 
 
 skirt 
 
 S 
 
 bread 
 
 9 
 
 iace 
 
 5 
 
 beef 11 
 
 vest 
 
 8 
 
 meat 
 
 16 
 
 tailor 
 
 9 
 
 turkey 17 
 
 meat 
 
 9 
 
 vest 
 
 2 
 
 turkey 
 
 8 
 
 tailor I 
 
 fruit 
 
 II 
 
 shoes 
 
 9 
 
 pudding 14 
 
 necktie 8 
 
 shoes 
 
 S 
 
 fruit 
 
 9 
 
 necktie 
 
 3 
 
 pudding 10 
 
 stockings 
 
 8 
 
 potato 
 
 IS 
 
 button 
 
 7 
 
 carrot 17 
 
 potato 
 
 9 
 
 stockings 
 
 3 
 
 carrot 
 
 10 
 
 button I 
 
 butter 
 
 12 
 
 woolen 
 
 9 
 
 dinner 
 
 14 
 
 shawl 6 
 
 woolen 
 
 5 
 
 butter 
 
 9 
 
 shawl 
 
 3 
 
 dinner 12 
 
 Since other tabulations show the same results as the one 
 submitted, one may conclude that the first word was given 
 the greater preference when it contained the more attractive 
 Idea; when the more attractive idea was second, the preference 
 for the first word either was much reduced or disappeared 
 entirely. Although with the majority of pupils it would ap- 
 pear that the two different kinds of preference — the one based 
 on idea, the other based on mere order of presentation — tended 
 now to reinforce and now to offset each other, yet with certain 
 individuals this is not true; they let themselves be influenced 
 solely by position, writing the first word (or the second word) 
 of the entire list of twenty words. Indeed, several wrote the 
 
PREFERENCES IN BOYS AND GIRLS 
 
 369 
 
 first (or second) word of more than one list. The following 
 tabulation throws some light on the influence of this factor 
 in the different grades. 
 
 Table C 
 
 Showing Selection of Words According to Position Exclusively 
 
 Second Grade. 
 
 First word . . 
 
 Second word 
 A Third Grade. . 
 
 First word . . 
 B Third Grade. . 
 
 First word . . 
 
 Second word 
 A Fourth Grade. 
 
 First word . . 
 
 Second word 
 B Fourth Grade. 
 
 First word . . 
 
 Second word , 
 A Fifth Grade. 
 
 First word . . 
 
 Second word . 
 B Fifth Grade. 
 
 First word . . 
 A Sixth Grade. 
 
 First word . . 
 
 Second word . 
 B Sixth Grade. 
 
 First word . . 
 
 Second word. 
 A Seventh Grade. 
 
 First word . . 
 B Seventh Grade. 
 
 First word . . 
 Eighth Grade. 
 
 First word. . 
 
 Second word . 
 
 Total 
 
 Girls 
 
 S girls 
 S girls 
 
 16 lists 
 8 lists 
 
 7 girls 9 lists 
 
 I girl 
 I girl 
 
 I girl 
 I girl 
 
 1 list 
 
 2 lists 
 
 I list 
 I list 
 
 1 girl I list 
 
 2 girls 2 lists 
 
 I girl 2 lists 
 
 7 girls 10 lists 
 
 S girls 8 lists 
 
 4 girls 13 lists 
 
 I girl 2 lists 
 
 3 girls 6 lists 
 
 6 girls 
 3 girls 
 
 12 lists 
 8 lists 
 
 54 girls 102 Hsts 
 
 Table C attracts one's attention to three points: 
 I. The influence of the factor of the position of the word is 
 more frequent in the lowest two grades, as is to be expected. 
 The excessive breaking out in the A sixth grade is puzzling; 
 yet among the girls, the preference for the first word and for 
 the second word tend to balance. In the eighth grade, one 
 might suspect a conspiracy among the girls, since nine out of 
 ten girls are influenced by the order of presentation. How- 
 ever, it seems improbable that any plan of writing the words 
 
370 M. I. STOCKTON 
 
 could have been prearranged, as the pupils did not know when 
 the words were to be presented. In fact, they were rather 
 led to think that each presentation was the last. 
 
 2. Table C shows that a certain order was followed in 
 one hundred and two lists among the girls and in seventy-nine 
 lists among the boys — giving this factor a greater frequency 
 among the girls in the ratio of lo to 8. This frequency among 
 the girls is still more pronounced, even when one allows for 
 the greater number of girls' papers. There were 648 girls' 
 lists of twenty words and 600 boys' lists of twenty words — 
 or a ratio of about 16 to 15. 
 
 3. This tabulation runs parallel at certain points with the 
 general preference based on the position of the words shown 
 in Table VII. In Table C, in the second grade, the prefer- 
 ences for the first word and for the second word are almost 
 balanced among boys and girls. In Table VII. there is a 
 comparatively small percentage of preference for the position 
 of the word shown in this grade. In the A and B fifth grades, 
 Table C shows little influence of this factor of the position 
 of the word; in Table VII. the percentage of preference is low. 
 In the A sixth grade, one would expect the preference for the 
 first word to more or less balance the preference for the 
 second word among the girls (Table C). But Table VII. 
 shows a marked preference for first words. However, among 
 the boys in that grade the two tables are parallel. The girls 
 of the eighth grade are greatly influenced by this factor of 
 the position of the words (Table C), and there is also a marked 
 preference shown in Table VII. Yet Table VII. gives a high 
 percentage of preference for the position of a word for the 
 boys of the eighth grade while Table C shows almost no 
 influence of this factor. However, the small number of boys 
 in this grade must be considered. 
 
 With reference to the first aspect of the larger problem; 
 namely, what inferences may be drawn from this experiment 
 concerning the differences in the affective life of boys and 
 girls of various ages, the results warrant the statement that 
 there is with age, a general, though very irregular, increase 
 in the preference shown for the various classes of ideas. 
 
PREFERENCES IN BOYS AND GIRLS 
 
 371 
 
 Furthermore, the preference Is more marked among the boys 
 than among the girls. The irregularities of the curves of 
 Plate F may be due to several reasons. At least eight nation- 
 alities are represented in these children, and In some of the 
 homes the parents do not speak English. And with a greater 
 number of children the curve would tend to be more regular; 
 150 boys and 162 girls are the basis for these curves. 
 
 It is also noticeable that In some of the grades the children 
 are over age. Ayers^ gives the following as the normal age: 
 
 Grade 2 3 4 5 6 7 8 
 
 Age 7-9 8-10 9-11 10-12 11-13 12-14 13-IS 
 
 The following (to repeat from Table A, p. 348) are the 
 average ages of the pupils In the present experiment: 
 
 Grade 
 
 2 
 
 A3 
 
 B3 
 
 A4 
 
 B4 
 
 A5 
 
 Age of boys 
 
 Age of girls 
 
 9-3 
 
 8.6 
 
 lO.I 
 
 9-3 
 
 10.9 
 
 9-3 
 
 10.9 
 II. 
 
 12.4 
 II.7 
 
 II-3 
 12. 1 
 
 Grade 
 
 Bs 
 
 A6 
 
 B6 
 
 A7 
 
 B7 
 
 8 
 
 Age of boys 
 
 Age of girls 
 
 13-9 
 12. 1 
 
 13-3 
 12.9 
 
 13-6 
 14. 
 
 13-6 
 12.9 
 
 14.5 
 14. 
 
 14.8 
 
 The table for the normal age Is given for the grade; i. e., 
 for the sixth grade, the normal age is from il to 13. Any 
 pupil in the sixth grade who is over 13 years of age is beyond 
 the normal age. Or, any pupil In the A sixth grade who is 
 over 12 years of age Is beyond the normal age. Glancing at 
 Table A, one finds that the boys in the B3, B4, B5, A6, B6 
 and By grades are beyond the normal age; the girls in the A3, 
 A4, B4, A5, A6 and B6 grades are beyond the normal age. 
 
 After studying the irregularities in the curves In Plate F, 
 one finds that In the grades In which the drops occur the 
 pupils are over age. In the boys' curve, the points are the 
 B3, B4 and By grades; in the girls' curve, the A3, A5 and A6 
 grades. Yet, the boys of the B5, A6 and B6 grades are also 
 above the normal age and at these points the curve is steadily 
 rising. The girls of the A4 and B6 grades are also above the 
 normal age and the curve Is rising at these points. In the 
 B4 grade, in which the girls are beyond the normal age, 
 their curve has reached one of the peaks. 
 
 1 'Laggards in Our Schools,' 1909, p. 38. 
 
372 M. I. STOCKTON 
 
 Considering the second aspect of the larger problem, these 
 curves would have been more comparable with the curves of 
 other studies if the age of the pupils instead of the grades had 
 been used as the basis for the curves. However, some rough 
 comparisons may be of interest. In a 'Study of Children's 
 Reading Tastes' by Miss Vostrovsky,^ curves are given which 
 show the increase, with age, in definiteness of answer to the 
 question "Why did you select your last book.?" The curves 
 show that the boys increase gradually in definiteness with no 
 drops, whereas the girls' increase is not so great nor so steady. 
 There are two drops in the girls' curve — at ten and at fifteen 
 years of age — and a sudden rise from fourteen to fifteen. 
 She infers from the results that boys are more independent 
 in their selection of books than are girls. 
 
 In a 'Study of Children's Superstitions '^ by the same 
 writer, a growth in the critical spirit as children become older 
 is shown. The curves showing the number of superstitions 
 described as untrue by boys and by girls display the same 
 differences between boys and girls as was mentioned in her 
 other study. About the same general difference between boys 
 and girls is shown in Plate F as was shown in Miss Vos- 
 trovsky's studies. 
 
 In Donaldson's^ showing of the variation in brain weight 
 during the first twenty-five years, the curves for both boys and 
 girls are far more regular than in my Plate F, and yet there 
 are some points of similarity. From eleven to thirteen years 
 of age, the boys' curves show a steady rise both in the prefer- 
 ences here studied and also in brain weight; then a drop in 
 both to fourteen and then a rise in both to fifteen. Among the 
 girls, there is a decided rise in both from thirteen to fourteen, 
 then a drop in both. Fourteen years is the highest point in 
 both. There is far less similarity between these curves of 
 Plate F and the two curves which Donaldson* gives of the 
 changes (A) in the length of the head and (B) in the breadth 
 of the head. 
 
 ^Pedagogical Seminary, Vol. 6, p. 523. 
 
 2 In Barnes' 'Studies in Education,' Vol. I, p. 123. 
 
 ''Growth of the Brain,' 1895, p. 105. 
 
 < 'Growth of the Brain,' 1895, p. 112. 
 
PREFERENCES IN BOYS AND GIRLS 373 
 
 Important curves for comparison are those given by Burk 
 in a study on the 'Growth of Children in Height and Weight.'^ 
 Two of these sets of curves give the annual percentage of 
 increase In weight (I. J.) and the annual percentage of increase 
 in height (K. L.) of the average American girl and boy. 
 There are several points of similarity between his curves I. J. 
 and my own F. The girls' curves drop from eight to nine 
 years in both; and twelve years, the highest point in I. J., 
 is one of the three peaks in F. However, there is a steady 
 rise from nine to twelve in I. J,; whereas in F. there is a drop 
 and then a rise before twelve years is reached. The boys' 
 curves I. J. and K. L. are similar from nine to fifteen years. 
 There is a drop from ten to eleven in these, comparable \o 
 that from A3 (10 yrs.) to B3 (11 yrs.) In F. But, in the 
 curves I. J. and K. L., there is a steady rise from eleven to 
 fifteen, the highest point; whereas in F, there is a drop from 
 A4 (11 yrs.) toB4 (12 yrs.) followed by a rise to A7 (13.6 yrs.), 
 the highest point; then another drop and another rise. 
 
 It is thus probable that there is some connection between 
 general physical and mental growth and the development of 
 the affective life, of which preference Is an aspect. 
 
 ^ The American Journal of Psychology, Vol. 9 (1897-98), p. 263. 
 
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