VOL. XXXII 
 
 no. 3 
 
 PSYCHOLOGICAL REVIEW PUBLICATIONS 
 
 WHOLE NO. H 5 
 1923 
 
 Psychological Monographs 
 
 EDITED BY 
 
 JAMES ROWLAND ANGELL, Yale University 
 HOWARD C. WARREN, Princeton University ( Review ) 
 
 JOHN B. WATSON, New York (J. of Exp. Psychol .) 
 
 SHEPHERD I. FRANZ, Govt. Hosp. for Insane {Bulletin) and 
 MADISON BENTLEY, University of Illinois {Index) 
 
 STUDIES FROM THE PSYCHOLOGICAL 
 LABORATORY OF OBERLIN COLLEGE 
 
 EDITED BY 
 
 RAYMOND HERBERT STETSON 
 
 Professor of Psychology 
 
 PSYCHOLOGICAL REVIEW COMPANY 
 PRINCETON, N. J. 
 
 Agents: G. E. STECHERT & CO., London (2 Star Yard, Carey St., W. C.) 
 
 Paris (16, rue de Conde) 
 
Digitized by the Internet Archive 
 in 2019 with funding from 
 Princeton Theological Seminary Library 
 
 https://archive.org/details/studiesfrompsychOOstet 
 
TABLE OF CONTENTS 
 
 I. The Hair Follicle and the Sense of Pressure. 
 
 By R. H. Stetson 
 
 II. Mechanism of the Different Types of Movement. 
 
 By R. H. Stetson, with a preliminary report of 
 experimental data by J. A. McDill 
 
 III. Measurements of Rhythmic Unit-Groups at Different 
 
 Tempos. By R. H. Stetson and T. E. Tuthill 
 
 IV. The Application of the Binet-Simon Tests to Groups 
 
 of White and Colored School Children. 
 
 By G. R. Wells 
 
 PAGE 
 
 I 
 
 18 
 
 4i 
 
 52 
 
THE HAIR FOLLICLE AND THE SENSE OF 
 
 PRESSURE 
 
 BY 
 
 R. H. Stetson 
 
 It has been assumed that the end-organs for pressure are lo¬ 
 cated at separate points, like those of warmth and cold. Careful 
 exploration of the skin by Goldscheider and v. Frey 1 revealed 
 separate spots where the sense of pressure reaches a maximum. 
 The intervening skin is also sensitive to pressure, but that may 
 be the result of the transmission of the stimulus through yielding 
 skin structures to the nearest ‘pressure spots.’ The actual end- 
 organs for warm and cold are in doubt, but it has seemed easy to 
 determine the end-organs for pressure. On hairy areas maximum 
 sensitiveness to pressure occurs at a spot to the ‘windward’ of 
 the hair, and is evidently due to the stimulation of the hair follicle. 
 The follicle lies embedded in the skin at an angle so that the 
 ‘pressure spot’ occurs over the follicle a millimeter or so from 
 the point where the hair emerges. It is easy to see the relation, 
 for stimulation of the ‘pressure spot’ moves the hair shaft. 
 
 The histology of the hair follicle reveals an elaborate innerva¬ 
 tion which might well mediate an important cutaneous quality. 
 A double innervation has been described and is a commonplace 
 in the text books . 2 A detailed account of the innervations of the 
 follicle with references to the original studies and with drawings 
 of the structures is given by Prenant and Bouin . 3 They speak 
 of the neural ring of non-medullated fibres which originate from 
 a nerve entering the follicle at the level of the opening of the 
 
 1 A. Goldscheider, Ges. Abhandl. I, 1898. v. Frey, Vorles. u. Physiol. 1894. 
 v. Frey, Ergebnisse d. Physiol. (Asher u. Spiro) 1913- Bd. 13, S. 96. Physiol, 
 d. Sinnesorgane d. mench. Haut. II, Der Drucksinn. 
 
 2 Stewart, Manual of Physiol., 1910; Howell, Physiol., 1896, p. 260; Bailey, 
 Histol., 1910, p. 365; Ferguson, Hor. Histol., 1905, p. 225; Piersol, Nor. Histol., 
 1910, p. 328. 
 
 3 Prenant et Bouin, Traite d’Histologie, 1911, p. 624 ff. 
 
2 
 
 R. H. STETSON 
 
 sebaceous glands. This neural ring is double and lies well out¬ 
 side the vitreous membrane. On the outside surface of the 
 vitreous membrane at the level of the neural ring and extending 
 below it are a number of enlarged, spatulate endings, possibly de¬ 
 rived from the fibrils of the ring. There is also an innervation 
 of the root proper of the hair, nerve fibres which enter the 
 papilla of the follicle at the lower end of the follicle. Szymono- 
 wicz 4 has made a detailed study of the innervation of the human 
 hair by the methylen blue method, and has been able to reconcile 
 the statements of previous authors. He speaks of the neural ring 
 and the flattened endings on the outside of the vitreous membrane 
 just below the sebaceous glands, and of the nerve entering the 
 papilla of the hair. His detailed drawings give an idea of the 
 form of the nerve endings and of their distribution. The ma¬ 
 terial used was freshly excised from the eyelid and from the 
 lower lip. The studies of the human hair follicle have been con¬ 
 fined to a few localities on the human body. 
 
 The tactile hairs of many mammals are undoubtedly important 
 touch organs, and have been studied. Their innervation is not 
 unlike that of the human hair; this increases the probability that 
 the human hair is an important tactile organ. 5 
 
 Actual experiment shows that the hair itself is an important 
 factor in the pressure sense. Vincent quotes Sherrington: “On 
 9 sq. cm. of skin from which the hairs have been shaved, the 
 liminal stimulus was found to be 36 mgm, whereas, on the same 
 surface before it was shaved, 2 mgm was the liminal stimulus.” 
 And it is well known that the hair itself is more sensitive to pres¬ 
 sure than the ‘pressure spot 1 near the hair. 
 
 Following v. Frey, Thumberg 6 and others speak of the hair 
 acting “as a lever, in that the neural stimulation may be described 
 as a moment of rotation wherein the surface of the skin acts as 
 
 4 L. Szymonowicz, Ub. die Nervenendigungen in d. Haaren d. Menchen, 
 Archiv. f. mikro. Anat. 1909, Bd. 74, S. 622-634. 
 
 5 S. B. Vincent, The tactile hairs cf the white rat, J. Comp. Neurol, v. 23, 
 !9I3> P- 1-38. J. E. Eckert, The innervation of the integument of Chiroptera, 
 J. of Morphol., 1914, v. 25, p. 315-320. 
 
 6 Nagel’s Handb. Ill, 1905, S. 664. 
 
THE HAIR FOLLICLE 
 
 3 
 
 a fulcrum.” This notion of the hair as a lever of the first class 
 in which the epidermis at the point of emergence acts as a fulcrum 
 so that the movement is transmitted to the follicle has been com¬ 
 monly accepted. It is apparent that the skin does act as a ful¬ 
 crum for the tactile hairs of animals when they are moved, and 
 something like that must take place when the human hair is 
 erected by the muscles of the hair follicles. Nevertheless the ob¬ 
 servation is inaccurate when applied to the human hair as a tactile 
 organ. 
 
 Despite this general acceptance of the hair follicle as the pres¬ 
 sure organ in hairy areas, there are certain acts not in accord. 
 It is hard to understand why the scalp and the bearded area of 
 the face should not be far more sensitive, if they are crowded 
 with pressure organs. Moreover the ‘pressure spots’ unlike the 
 warm and cold spots, are but points of maximum sensitiveness, 
 and the skin is everywhere sensitive to pressure. Murray 7 speaks 
 of the difficulty of a precise localization of the ‘pressure spots,’ 
 and of the apparent existence in the intermediate areas of other 
 spots of approximately equal sensitiveness, and of the impos¬ 
 sibility of reproducing the granular sensation by electrical stimu¬ 
 lation of the verified spots. The extreme delicacy of the response 
 when the skin is lightly touched with cotton, etc. makes it doubt¬ 
 ful if there is transmission to such deep-lying structures as the 
 follicles. Merkel 8 hazarded the guess that certain simple end- 
 organs scattered in the skin as well as about the hair follicles were 
 “touch corpuscles.” And certainly Murray’s statement: “The 
 greater efficiency of pressure over the hair bulb in the production 
 of the pressure sensation is probably due to the mechanical effect 
 through the grinding down of the comparatively solid follicle 
 upon the underlying endings” is worth noting. There is good 
 reason to consider his assertion that “the so-called granular pres¬ 
 sure is not in itself an element but is a complex of deeper pressure 
 with contact. . . . ” 9 
 
 7 E. Murray, Qual. Anal, of Tickle, Am. J. Psy. 1908, v. 19 (3), p. 299. 
 
 8 F. R. Merkel, Tastzellen in Tastkorperchen bei d. Hausthieren u. b. Men- 
 chen, Archiv f. mikro Anat. 1876, Bd. 11, S. 647. 
 
 9 Murray, ibid. 
 
4 
 
 R. H. STETSON 
 
 PROBLEM 
 
 It is possible to investigate the function of the hair follicle as 
 an end-organ for the sense of pressure by two methods: 
 
 1) The neural endings of the follicle may be removed, and the 
 effect on the sensitiveness of the hair itself and of the adjacent 
 areas studied; 
 
 2) The pressure sensitivity of areas denuded of follicles may 
 be investigated. 
 
 Before operating the hair follicle, preliminary studies of the 
 movements of the follicle and the resulting sensations were made. 
 The skin, carefully scrubbed and softened, was moistened with a 
 little water and glycerin, and examined with a Zeiss binocular 
 erecting microscope magnifying c.9 times. A strong red light 
 was used for illuminating; unlike the white light the red light 
 is not reflected, rendering the surface opaque, and it penetrates 
 the skin to a slight depth. By this means the hair-shaft of a dark¬ 
 haired subject may be traced about two millimeters into the skin, 
 and the movement of the follicle noted when stimulation is ap¬ 
 plied. 
 
 On moving the hair on back of hand or on forearm, under 
 such conditions, it is easy to see that the description of the hair 
 as a lever of the first class is inaccurate. The lower end of the 
 follicle is far more firmly fixed than the surface where the hair 
 emerges, and the movement affects the lower end little if at all, 
 while the upper part of the follicle and the skin at the point of 
 emergence undergo considerable deformation. The hair is a 
 lever of the second class, with the fulcrum at the lower end of 
 the follicle, rather than a lever of the first class with the fulcrum 
 at the surface where the hair emerges. The hair is like a willow 
 shoot deeply rooted in light sand; when the shoot is moved, the 
 part just below the surface, and the surface layer of the sand 
 itself are stirred, but the root of the willow shoot is not moved. 
 
 For a careful study of the movements of the follicle including 
 the papilla, the hairs of the scrotum were used; the skin is thin 
 and transparent, the follicles large and single, and the papilla 
 clearly defined by a pigmented spot. On the scrotum as else- 
 
THE HAIR FOLLICLE 
 
 5 
 
 where, the movement of the skin about the point where the hair 
 emerges is a most striking item in the stimulation of the hair. 
 The skin may be fixed with collodion, and the lower end of the 
 follicle moved two millimeters without causing sensation. This 
 was verified by repeated observations on several hairs on each 
 of three subjects, two of whom were trained observers. 
 
 When traction is exerted on the hair it is easy to see that the 
 lower part of the follicle is not the significant point; the end of 
 the follicle may be moved back and forth two or three millimeters 
 without the sensation of pulling being noted. On the other hand, 
 if the skin is fixated by putting a blunt point, or a hook partly 
 encircling the hair, into the pit of the hair, a slight traction is 
 quickly perceived; much greater traction must be exerted if the 
 skin is not fixated. This indicates that the pressure sensations 
 are mediated by the upper part of the follicle, and possibly by 
 the skin surface at the point of emergence. These observations 
 were verified on several hairs on each of five subjects, two of 
 whom were trained observers. 
 
 OPERATION ON THE HAIR FOLLICLE 
 
 Removal of the lower part of the Follicle . 10 
 
 The area selected for the operation was the anterior portion of 
 the scrotum near the median line. The surface is fairly sensitive 
 to pressure, and the localization is about as good as on the fore¬ 
 arm. The follicles are easily seen and operated. They are single 
 and widely separated, as in no other part of the body. A strong 
 red light was used, and the work was done under the binocular 
 with a magnification of c. 9 times. To fixate the follicle, a No. 
 14 or 16 needle (f.n. in Fig. 1) in which a minute bend had been 
 made was passed through the skin, under the follicle at right 
 angles, and out on the other side, pinning the follicle in a tiny 
 stitch in the skin (Figs. 1 and 2). The follicle lay in the bend 
 of the needle (Fig. 2). Without local anesthesia, a transverse in- 
 
 10 Mr. C. C. W. Nicol, Assistant in the Oberlin Laboratory 1912-13, assisted 
 in the development of a rather difficult and exacting technic, and did a part 
 of the tedious work of operating and testing the hair follicles. 
 
6 
 
 R. H. STETSON 
 
 Tfg.l 
 
 cision was made just over the needle (i in Figs, i and 3) with 
 a small scalpel ground out of a needle; then the papilla (c, in 
 Fig. 3) with about half a millimeter of the follicle was snipped 
 off (at d in Fig. 3) with scissors ground to fine slim points. The 
 severed portion was removed with fine tweezers. It is unneces¬ 
 sary to snip off the lower part of the follicle; dissecting it loose 
 breaks all connections; but for the sake of certainty the lower part 
 of the follicle was always removed. The operations were done 
 with the usual precautions, without local anesthesia. The tissues 
 are resistent to infection and the wounds heal very rapidly. There 
 
THE HAIR FOLLICLE 
 
 7 
 
 cross-section at b' 
 
8 
 
 K. H. STETSON 
 
 was a slight induration about the scar, but the reaction had dis¬ 
 appeared, and the wounds were practically healed in two days. 
 
 Lower part of the follicle removed, on scrotum: when tested the 
 stimulus was applied to the hair. 
 
 St. 3 follicles operated, tested 48 hrs. later 
 
 
 2 
 
 a 
 
 a 
 
 a 
 
 u 
 
 u 
 
 u 
 
 
 
 L. 
 
 5 
 
 u 
 
 a 
 
 a 
 
 a 
 
 a 
 
 a 
 
 Follicles 
 
 in a group 
 
 
 7 
 
 6 
 
 u 
 
 a 
 
 a 
 
 u 
 
 a 
 
 a 
 
 it 
 
 « a 
 
 N. 
 
 a 
 
 a 
 
 a 
 
 a 
 
 a 
 
 a 
 
 it 
 
 a u 
 
 
 7 
 
 8 
 
 it 
 
 a 
 
 a 
 
 a 
 
 a 
 
 u 
 
 it 
 
 n a 
 
 S. 
 
 u 
 
 a 
 
 a 
 
 n 
 
 a 
 
 a 
 
 it 
 
 a a 
 
 
 1 
 
 a 
 
 a 
 
 a 
 
 a 
 
 a 
 
 a 
 
 it 
 
 a a 
 
 
 Q 
 
 a 
 
 a 
 
 a 
 
 a 
 
 a 
 
 a 
 
 U 
 
 a a 
 
 I 
 
 48 
 
 In every case every hair was sensitive after the operation, and 
 there was no difference in quality or localization whereby the 
 operated hairs could be distinguished from the neighboring nor¬ 
 mal hairs by any of the subjects, two of whom were trained ob¬ 
 servers. Care was taken, of course, in applying the stimulus to 
 the hair shaft, not to touch the skin or other hairs; if necessary 
 the microscope was used in stimulating and observing the hairs. 
 
 When tested with the v. Frey esthesiometer, in all cases the 
 skin about the point of emergence and between the operated hairs 
 was as sensitive as the neighboring normal areas. The sensitive¬ 
 ness was somewhat reduced on the ‘pressure spots’ as they were 
 near slightly indurated scars. (E.g. readings for normal ‘pres¬ 
 sure spots’ 14-15, for intermediate areas 16-18, for indurated 
 scars 20-23.) 
 
 The v.Frey esthesiometer used throughout the tests was fur¬ 
 nished with a ‘hair’ made by reducing a steel hair-spring in a bath 
 of dilute nitric acid. A tip was made by inserting the hair-spring 
 in flame and producing a globule of oxid, or by attaching a globule 
 of hard cement; the oxid or cement is ground down on a fine 
 carborundum hone to the proper dimensions. Such a ‘hair’ does 
 not lose its elasticity, is very uniform throughout its length, and 
 is not affected by moisture. 
 
 As to the precise sensitiveness of the operated hairs, it was the 
 
THE HAIR FOLLICLE 
 
 9 
 
 judgment of both experimenters that the operated hairs were 
 slightly less sensitive than the normal hairs; the subjects could 
 make no such discrimination. It is of course difficult to get any 
 quantitative tests for stimulation of a hair, and nothing could 
 be based on this judgment. A slight reduction of sensitiveness 
 might well be expected from the disturbance and from the slight 
 induration which limited the movement of the follicle and of the 
 skin. 
 
 Whether the papilla is removed, or merely dissected loose, the 
 hair falls out in a week or so; but it remains in place long enough 
 for tests. The time (two days) between operation and test is 
 of course much too short for any regeneration of the nerve 
 fibrils. 
 
 Removal of the Upper Part of the Follicle 
 
 It is agreed that the nerve supplying the elaborate innervation 
 of the upper part of the follicle enters at the level of the opening 
 of the sebaceous glands, and that the neural ring and the flattened 
 endings are just below the glands. The sebaceous glands are 
 easily seen on the scrotum. It is possible to remove the upper 
 part of the follicle so as certainly to eliminate the upper innerva¬ 
 tion of the follicle. 
 
 The follicle was fixated by pinning it transversely into a tiny 
 stitch in the skin (Fig. i) ; the follicle lies in a minute bend of the 
 needle (Fig. 2). A transverse incision (i, Fig. 1 and 3) is made 
 in the skin just above the needle. The upper part of the follicle 
 is carefully dissected from the skin by inserting beneath the skin 
 a spade-shaped blade with rounded end; then with a hook-shaped 
 blade sharp on both inner and outer curves, the upper part of 
 the follicle is freed at the sides and beneath, down to the level 
 of the fixating needle (f. n., Fig. 3). Care is taken not to pierce 
 the skin. With a pair of special tweezers the tough, elastic vit¬ 
 reous membrane is stripped off the hair, beginning at the level 
 of the fixating needle (f.n., Fig. 3) and working under the skin 
 until the follicle has been stripped out to the point of emergence. 
 The hair shaft is left in place. 
 
10 
 
 R. H. STETSON 
 
 The knives were ground from No. 5 needles. The tweezers 
 were made of two “crow-quill” steel pens carefully ground until 
 the points are very slender. The four minute strips of steel were 
 then bent at the tips until slightly hooked and ground sharp at 
 the squared tips. These four prongs encircle the hair and strip 
 away the follicle, but are elastic enough not to tear the hair. 
 
 In this fashion the follicle is cleared away for about one-half 
 its length; care is taken not to disturb the lower end of the follicle. 
 The transverse incision is 1.5-3 mm. from the emergence point 
 and the skin about the hair is intact. The reaction subsides in a 
 day or so and the wound heals in a very short time, leaving the 
 hair uninjured—unlike the first operation. 
 
 Removal of the upper part of the follicle on scrotum; when 
 tested the stimulus was applied to the hair. 
 
 St. I 
 
 follicles; 
 
 tested after 
 
 48 hrs. 
 
 Sensation nearly normal 
 
 I 
 
 u 
 
 a 
 
 a 
 
 48 
 
 a 
 
 a 
 
 decidedly subnormal 
 
 Ni. 3 
 
 u 
 
 a 
 
 a 
 
 12 
 
 a 
 
 a 
 
 normal; after 48 hrs. 
 normal 
 
 St. 4 
 
 u 
 
 a 
 
 a 
 
 12 
 
 a 
 
 a 
 
 normal 
 
 P. 1 
 
 u 
 
 a 
 
 a 
 
 12 
 
 a 
 
 a 
 
 normal 
 
 M. 3 
 
 a 
 
 a 
 
 a 
 
 12 
 
 a 
 
 a 
 
 normal 
 
 1 
 
 a 
 
 << 
 
 a 
 
 12 
 
 a 
 
 a 
 
 decidedly subnormal; after 48 
 hrs. c. normal 
 
 K. 5 
 
 a 
 
 a 
 
 a 
 
 12 
 
 a 
 
 a 
 
 normal; after 48 hrs. nor¬ 
 mal. Follicles in a group. 
 
 Ma. 5 
 
 a 
 
 a 
 
 a 
 
 12 
 
 a 
 
 a 
 
 normal; after 48 hrs. nor¬ 
 mal. Follicles in a group. 
 
 M. 4 
 
 a 
 
 a 
 
 a 
 
 12 
 
 a 
 
 a 
 
 normal 
 
 St. 4 
 
 a 
 
 a 
 
 a 
 
 48 
 
 a 
 
 a 
 
 normal. These hairs were 
 compared with normal 
 hairs which had been 
 scarified without injuring 
 the follicle; no difference 
 found. 
 
 K. 4 
 
 a 
 
 a 
 
 a 
 
 12 
 
 a 
 
 a 
 
 normal; after 4 days, nor¬ 
 mal. 
 
 Ni. 3 
 
 a 
 
 a 
 
 a 
 
 12 
 
 a 
 
 a 
 
 normal 
 
 1 
 
 a 
 
 a 
 
 a 
 
 12 
 
 a 
 
 a 
 
 slightly subnormal 
 
 L. 1 
 
 a 
 
 a 
 
 a 
 
 12 
 
 a 
 
 a 
 
 decidedly subnormal 
 
 1 
 
 a 
 
 a 
 
 a 
 
 12 
 
 a 
 
 a 
 
 slightly subnormal 
 
 Ni. 2 
 
 a 
 
 a 
 
 a 
 
 24 
 
 a 
 
 a 
 
 slightly subnormal 
 
 K. 4 
 
 a 
 
 a 
 
 a 
 
 12 
 
 a 
 
 a 
 
 subnormal; 4 days after, 
 subnormal. 
 
THE HAIR FOLLICLE 
 
 ii 
 
 s. 
 
 1 “ 
 
 it 
 
 tt 
 
 48 
 
 a 
 
 “ normal 
 
 
 1 “ 
 
 tt 
 
 ti 
 
 48 
 
 u 
 
 decidedly abnormal; scar 
 tissue. 
 
 L. 
 
 1 “ 
 
 a 
 
 a 
 
 24 
 
 tt 
 
 “ normal 
 
 
 1 
 
 tt 
 
 tt 
 
 24 
 
 n 
 
 slightly abnormal 
 
 T. 
 
 2 “ 
 
 a 
 
 a 
 
 24 
 
 a 
 
 subnormal; 48 hrs. after, 
 
 normal 
 
 Ma. 
 
 2 “ 
 
 a 
 
 u 
 
 24 
 
 a 
 
 “ normal 
 
 K. 
 
 1 “ 
 
 tt 
 
 a 
 
 24 
 
 a 
 
 decidedly subnormal; 3 days 
 after, slightly subnormal. 
 
 
 1 “ 
 
 a 
 
 n 
 
 72 
 
 n 
 
 “ normal 
 
 S. 
 
 3 
 
 tt 
 
 a 
 
 24 
 
 a 
 
 sensation subnormal; 48 hrs. 
 after, slightly subnormal. 
 
 L. 
 
 1 
 
 tt 
 
 tt 
 
 48 
 
 tt 
 
 “ slightly subnormal 
 
 Ma. 
 
 1 
 
 tt 
 
 tt 
 
 48 
 
 a 
 
 slightly subnormal 
 
 63 hairs operated on eight subjects. 
 
 Of these 63 follicles, 4 proved to be decidedly subnormal, though 
 not insensitive; it is possible that in those cases the nerves of 
 the skin were severed, or the formation of scar tissue involved 
 the fibers supplying the skin about the hair. 
 
 From these results it is easily seen that there is a tendency to 
 reduction of the sensitiveness of the hair when the upper innerva¬ 
 tion of the follicle is removed. In many cases this is not apparent 
 on scrotal areas but it comes out more plainly on other parts of 
 the body. 
 
 The lower arm has been much used for study of skin sensa¬ 
 tions. It is not entirely satisfactory for the present purpose, be¬ 
 cause it is difficult to find single hairs. On nearly all parts of the 
 body the hairs are closely set in threes, one large hair with a small 
 guard-hair on either side. 
 
 Removal of upper half of follicle on lower arm; when tested 
 the stimulus was applied to the hair. 
 
 St. 2 follicles; tested after 24 hrs. Subnormal: 2 days after, subnormal. 
 
 2 “ “ “ 48 “ Subnormal 
 
 Tu. 2 “ “ “ 48 “ Subnormal 
 
 M. 1 “ “ “ 6 days Subnormal 
 
 Removal of the upper half on upper leg, just above patella; 
 when tested the stimulus was applied to the hair. 
 
 St. 2 follicles; tested after 24 hrs. Subnormal; 6 days after nearly normal. 
 
 2 “ “ “ 24 “ Subnormal; 4 days after nearly normal. 
 
12 
 
 R. H. STETSON 
 
 Removal of upper half of follicle on lower leg; when tested 
 the stimulus was applied to the hair. 
 
 L. 4 follicles; tested after 48 hrs. Subnormal 
 
 2 “ “ “ 4 days Subnormal 
 
 M. 3 “ “ “ 48 hrs. Subnormal 
 
 2 “ “ “ 48 “ Subnormal 
 
 The point of the hip, just outside the area of pubic hair is a 
 good locality for testing hair follicles; the hairs are large, sparse, 
 and single. 
 
 Upper half of the follicle removed on point of hip; when tested 
 the stimulus was applied to the hair. 
 
 St. 
 
 6 
 
 follicles: 
 
 tested after 
 
 6 days, 
 
 Subnormal 
 
 M. 
 
 2 
 
 ii 
 
 ii 
 
 a 
 
 4 
 
 ii 
 
 Subnormal 
 
 
 3 
 
 ii 
 
 ii 
 
 a 
 
 2 
 
 ii 
 
 Nearly normal 
 
 Ni. 
 
 3 
 
 ii 
 
 a 
 
 a 
 
 2 
 
 ii 
 
 Subnormal 
 
 
 4 
 
 a 
 
 ii 
 
 a 
 
 4 
 
 ii 
 
 Slightly subnormal 
 
 L. 
 
 2 
 
 a 
 
 a 
 
 a 
 
 4 
 
 ii 
 
 Subnormal 
 
 
 2 
 
 a 
 
 a 
 
 a 
 
 4 
 
 ii 
 
 Nearly normal 
 
 N. 
 
 4 
 
 a 
 
 a 
 
 a 
 
 12 
 
 hrs. 
 
 Subnormal 
 
 Sh. 
 
 5 
 
 a 
 
 a 
 
 a 
 
 11 
 
 days Subnormal 
 
 L. 
 
 1 
 
 ii 
 
 a 
 
 a 
 
 6 
 
 ii 
 
 Subnormal 
 
 M. 
 
 1 
 
 a 
 
 a 
 
 a 
 
 2 
 
 ii 
 
 Subnormal 
 
 
 1 
 
 a 
 
 a 
 
 a 
 
 2 
 
 ii 
 
 Almost normal 
 
 (The interval between operating and testing was lengthened because more 
 time was needed for healing.) 
 
 In all these cases the removal of the upper part of the follicle, 
 the quality of the hair sensation is not changed; the subjects are 
 unable to discriminate between the operated hairs and the neigh¬ 
 boring hairs. It is evident however that there is a decided re¬ 
 duction of the sensitiveness of the hairs operated on other parts 
 than the scrotum. That this does not occur more often on the 
 scrotum is probably due to the greater size and rigidity of the 
 hair, and the greater mobility of the surface, whereby the move¬ 
 ment of the hair-shaft produces a decided deformation of the 
 skin. 
 
 Removal of both Upper and Lozver Innervations of the Follicle 
 
 Although the preliminary experiments, and the removal of the 
 lower end of the follicle indicate that the lower innervation of 
 
THE HAIR FOLLICLE 
 
 13 
 
 the follicle has no influence on the pressure sensation, it is pos¬ 
 sible to argue that the pressure sensation remaining after the re¬ 
 moval of the upper half of the follicle is not due to the deforma¬ 
 tion of the skin about the hair, but to the stimulation of the lower 
 innervation. To test this, a number of hairs were subjected to 
 both operations. The upper part of the follicle was removed, the 
 wound allowed to heal, and then the lower part of the follicle 
 was exsected. The hair was then little more than a bristle set in 
 a mass of scar tissue. 
 
 Removal of upper and lower innervations of follicle on scrotum; 
 when tested the stimulus was applied to the hair. 
 
 M. 2 follicles; tested 24 hrs. after 2d operation. Probably slightly sub¬ 
 normal. 
 
 4 
 
 ii 
 
 ii - . ii ii ii 
 
 a 
 
 Probably slightly sub¬ 
 
 
 
 
 
 normal. 
 
 
 
 3 days “ “ 
 
 a 
 
 Normal 
 
 W. 3 
 
 ii 
 
 “ 24 hrs. “ “ 
 
 a 
 
 Slightly subnormal 
 
 4 
 
 ii 
 
 ii ^ . ii ii ii 
 
 a 
 
 Slightly subnormal 
 
 On stimulating such hairs, the sensation must come of course 
 from the skin at the point of emergence. The scrotal hairs are 
 well isolated, and there is little chance of diffusion of the stimulus 
 to neighboring follicles. The experiments on three subjects show 
 that the removal of both innervations gives the same result as 
 the removal of the upper innervation. There is every reason to 
 assume that the papilla is not a sensory end-organ of any sort. 
 
 Removal of the Entire Follicle 
 
 When the follicles are entirely removed from a hairy surface, 
 any response to light pressure must be due to end-organs in the 
 skin surface. 
 
 Areas were selected on the scrotum where the single follicles 
 are well defined; the skin is transparent and it is possible to 
 locate and extirpate every follicle with certainty. The follicles 
 were removed entire. The wounds were small, there was very 
 little reaction (no local anesthesia was used) and the healing was 
 very rapid. From 10 to 20 follicles were removed from each 
 territory. 
 
14 
 
 R. H. STETSON 
 
 M. An area 2.5 sq. cm. was cleared; tested 24 hrs. after with 
 probe showed some insensitiveness. Three days after, tested 
 carefully with the v. Frey apparatus it was impossible to detect 
 any change of the intermediate areas within the denuded territory. 
 The scars themselves were slightly less sensitive. 
 
 K. 3 sq. cm. Tested three days after clearing. With v. Frey 
 apparatus no difference could be detected save in the scars which 
 were much below normal. 
 
 S. 2 sq. cm. Tested 12 hours after clearing. ‘Pressure 
 spots’ of normal territory show lower threshold (14) than in¬ 
 termediate areas of either denuded or normal territories. Calls 
 stimulation of normal ‘pressure spot’ “hair.” Intermediate areas 
 give the same reading (17) in normal and denuded skin. Tested 
 after six days, the ‘pressure spots’ of normal territory have 
 lowest threshold (15); intermediate areas in both normal and 
 denuded skin give 17. The pressure spots of the normal areas 
 are easily deformed. The scars of denuded area are thickened, 
 and not easily deformed, and give a reading of 19-22. 
 
 L. 3 sq. cm. Tested 8 days after clearing. No difference 
 could be detected between normal and denuded territories, save 
 that the slightly indurated scars were less sensitive. The dilute 
 alcohol used for asepsis had tanned and thickened all the skin 
 slightly. 
 
 Ma. 3 sq. cm. Tested 5 days after clearing. No difference 
 between the normal and denuded territories, save that the scars 
 which do not deform easily, are not as sensitive as other areas. 
 The normal ‘pressure spots’ are no more sensitive than the in¬ 
 termediate areas; they do not deform as easily as in the case of S. 
 
 W. 2 sq. cm. Tested 10 days after clearing. No difference 
 between the normal and denuded territories, and threshold is not 
 lower for the normal ‘pressure spots,’ which do not deform easily. 
 The thickened scars are relatively insensitive and do not deform 
 readily. 
 
 In all these cases, care was taken to test out several localities 
 within and without the denuded territory, and to select places 
 well within the denuded territory, so that there might be no possi- 
 
THE HAIR FOLLICLE 
 
 15 
 
 bility of diffusion of the stimulus to normal end-organs. The 
 tissue of the scrotum is so yielding and flexible that such trans¬ 
 mission is improbable in any case. 
 
 In these cases the power of localization, the threshold for light 
 touch and for tickle all seemed the same in the normal and in 
 the denuded territories. 
 
 In the various operations on the hair follicle it is noteworthy 
 that there are no pain endings found in the follicle. On the 
 scrotum there are no pain endings to be found in the subcutaneous 
 fibres. On the other surfaces, many pain endings are met with 
 in the subcutaneous tissue. The scrotum gives but little pain 
 sensation; the lower arm, lower leg, and point of hip are about 
 equally sensitive; the leg just above patella gives very acute pain 
 sensation and few subjects are able to bear operations there with¬ 
 out local anesthesia. The differences in the sensitiveness to pain 
 of different localities is very striking. 
 
 Examination of Extensive Scars 
 
 A number of large scars where the skin had been destroyed 
 were carefully examined. The area was first searched for traces 
 of follicles, which can easily be detected when the surface is rubbed 
 down, moistened, and examined under a binocular with red light. 
 Nineteen scars on 17 subjects were studied. The scars occurred 
 on various parts of the body but mainly on the lower leg and 
 lower arm. In most cases the threshold for pressure was below 
 that of the bordering area; this varied somewhat with the thick¬ 
 ness of the scar epidermis. Localization did not seem to be 
 affected. Two scars which were heavily indurated and covered 
 with a thickened skin, were quite insensitive, and did not give 
 the results of the other 17. 
 
 An attempt was made to imitate the hair sensation on these 19 
 scar areas. Artificial ‘hairs’ were made 1) by inserting a fine 
 elastic needle into the epidermis, 2) by cementing onto the scar 
 surface a bit of hair-spring or fine wire bent at the base into a 
 tiny foot. A stimulator consisting of a bit of reduced hair-spring 
 tipped with a little ball of collodion was applied with quick taps. 
 
i6 
 
 R. H. STETSON 
 
 In 17 cases, on as many subjects, it was easy to imitate hair 
 sensations, so that the subject could not tell the false ‘hairs’ from 
 the normal hairs of the bordering areas. The confusion was 
 complete. 
 
 Artificial ‘hairs’ were mounted on three trained subjects on the 
 back of the hand between the normal hairs. It was impossible to 
 discriminate the false from the normal hairs. 
 
 Artificial ‘hairs' were mounted on three trained subjects on the 
 hairless palmar area (at ball of thumb on outer edge of hand) 
 near the hairy area, and compared with normal hairs. Subjects 
 were quite unable to distinguish between the false and the normal 
 hairs. 
 
 These experiments with artificial hair sensations on scars and 
 on the hairless areas tend to show that the hair sensation has no 
 peculiar quality, but may be due entirely to the deformation of 
 the skin surface, in the absence of hair follicles. In general the 
 artificial ‘hairs’ seemed to give a less intense sensation; but there 
 was no qualitative difference. In such work the method of ask¬ 
 ing the subject to discriminate between the real and the artificial 
 stimulus gives convincing results; it is capable of extension to 
 other types of skin sensation. 
 
 Conclusions 
 
 The hair as a sensory apparatus is like a willow shoot deeply 
 rooted in loose sand. When the hair-shaft is moved the move¬ 
 ment is greatest at the surface; pressure is exerted on the neural 
 rings, etc., which make up the upper innervation of the follicle; 
 often there is compression of the rings between the hair follicle 
 and the surface; at the same time the surface of the skin at the 
 point where the hair emerges is freely moved. 
 
 It is practically certain that the lower innervation of the 
 papilla of the hair is not a sensory organ. The sensation of the 
 hair, then, results from 1) the compression of the upper innerva¬ 
 tion (b in fig. 3) and 2) from the deformation of the skin 
 surface at the point of emergence (a in Fig. 3). There is no 
 qualitative difference between the two factors. 
 
THE HAIR FOLLICLE 
 
 1 7 
 
 When pressure is applied to the ‘pressure spot/ the resulting 
 stimulus is complex: i) there is stimulation of the skin surface 
 at the point (a in Fig. 3), 2) compression of the upper innerva¬ 
 tion of the follicle (b in Fig. 3), and 3) deformation of the 
 skin at the point of emergence by the pressure transmitted by 
 the hair-shaft (a in Fig. 3). 
 
 Tests of denuded areas and of scars show that hair follicles 
 are not essential to any variety of pressure or touch sensation, 
 and that the threshold for pressure is but slightly lowered by the 
 removal of the follicles. 
 
 In the hairy areas the end-organs for touch, then, are not con¬ 
 fined to the hair follicles, but are found throughout the skin sur¬ 
 face, and they are regenerated in epithelial scar tissue. The in¬ 
 nervation of the hair papilla is not a sensory end-organ. The 
 hair follicle is not furnished with endings for pain. 
 
MECHANISM OF THE DIFFERENT TYPES 
 
 OF MOVEMENT 
 
 R. H. Stetson 
 
 WITH A PRELIMINARY REPORT OF EXPERIMENTAL DATA 
 
 James A. McDill 
 
 The fundamental thing in the process called a movement is 
 the muscular contractions; the extent of actual change of position 
 of the member involved depends on conditions. The movement 
 of the member is the usual purpose of muscular action and move¬ 
 ment is often taken as the index of muscular action. In rapid, 
 repeated movements it is probable that change of position of the 
 moving member is of importance in the cycle of neuro-muscular 
 changes on which innervation and coordination depend. 
 
 In the action of muscles against immovable or slowly moving 
 resistance the individual muscular impulses are difficult to detect 
 and the nature of the reaction is obscured. In the following dis¬ 
 cussion such actions are not considered. Movements are defined 
 as reactions in which the contraction of the muscles affect the 
 position of the moving member. 
 
 Classification of Movements 
 
 1. Fixation; in which groups of opposing muscles are con¬ 
 tracted against each other. This is the movement of 
 holding still. 
 
 2. The slow movement; in which the groups of opposing 
 muscles are contracted but with uneven tension so that 
 change of position of the moving member results. Often 
 called the “controlled movement” because it can be changed 
 at any point in its course. 
 
 3. The rapid movement; which cannot be changed at every 
 point in its course but is usually determined entirely be¬ 
 fore the movement begins. The movement is a matter 
 
 18 
 
MECHANISM OF THE DIFFERENT TYPES 
 
 19 
 
 of preliminary set, “Einstellung.” Two kinds of rapid 
 movement may be distinguished. 
 
 A. Movements in which there is a tension in all the 
 opposing muscle groups throughout the movement. 
 
 B. Movements in which the contraction of the positive 
 muscle group relaxes long before the end of the 
 movement; the termination of the movement may 
 be due to the contraction of the antagonistic muscles. 
 This kind of movement was named by Richer “ball¬ 
 istic'’ because the moving member is actually free 
 from muscular tension in the middle of its course 
 and is carried on by its own momentum. 
 
 I. Fixation—The Movement of Holding Still. 
 
 All the various fixations of joints and members are of this 
 type. Every ordinary distal movement requires a proximal fixa¬ 
 tion. Postures are of course movements of holding still. Re¬ 
 cent work has shown that “muscle tonus’’ is merely a posture 
 reflex. 1 • 
 
 A record of the movement of holding still, as of a hand holding 
 stylus or of a finger tipped with writing point, shows that the 
 member is only approximately at rest. The member describes to- 
 and-fro movements about a center. In a common form of the 
 “steadiness test,” a stylus is held in holes of varying diameter 
 and the extreme amplitude of the movement determined. For 
 the purpose of comparing and relating types of movement the 
 number of tremors per second is more important than the ampli¬ 
 tude. Lueiani notes such a definite tremor in case of an out¬ 
 stretched arm. 2 He quotes Richet as giving 10-11 per sec. as 
 the frequency of tremor. F. B. Dresslar studying rapid volun¬ 
 tary movement determined the tremor of the members involved. 
 Forearm—12.2. per sec. 
 
 Wrist, lateral—12.9 per sec. 3 
 
 1 Sherrington, C. S. Postural activity of muscles and nerves, Brain, 38, ’15, 
 191. Langelaan, J. W. On muscle tonus, ibid., 235. 
 
 2 Human Physiology (’13) ’i 5 > 5 ^ 3 - 
 
 3 Some influences which affect the rapidity of voluntary movements, Am. 
 
 J. Psy. 4 , ’9i-’92, 514- 
 
20 
 
 R. H. STETSON AND JAMES A. MC DILL 
 
 It has been assumed that this muscular tremor denotes the 
 rate of synaptic reflex discharge through the motor nerve into 
 muscles. Luciani quotes Horseley and Schafer, 4 and Sherrington 
 quotes Schafer; 5 but more recent studies have made it clear that 
 this unit of muscular movement cannot be referred directly to 
 the frequency of impulses in the motor nerve. 6 The reflex 
 motor nerve frequency is given as 50-150 per sec. And it is 
 noted that there are 3-4 neural impulses for each muscle twitch. 
 It is true that tetanus occurs in skeletal muscle if the frequency 
 of the sensory stimuli is greater than 15 per sec., 7 but this does 
 not mean that there is a single motor impulse for each sensory 
 stimulus; instead there is a train of motor impulses for each 
 sensory stimulus. 8 
 
 For some time the attention of investigators was centered on 
 this frequency of c.50 per sec. as indicated by the action currents 
 from the muscles. Recently De Meyer has published a series of 
 studies in which he points out that the curves of previous in¬ 
 vestigators show other and lower frequencies superimposed on 
 the c.50 per sec. rate. Laboratory work shows that there are 
 currents of deformation of muscle due to any lengthening or 
 shortening of muscle, as well as action currents due presumably 
 to chemical changes in the myofibrillae. 9 The lower frequencies 
 noted by De Meyer are of the order of 10 per sec., and are prob¬ 
 ably to be identified with tremor. 
 
 One might be inclined to say that the chemical changes which 
 register themselves in action currents did not appear as actual 
 
 4 Ibid., 562. 
 
 5 Integ. Act. N. Sys. 206. 
 
 6 Beritoff, J. S. Zschr. f. Biol., 64, ’14, 161; and Piper, Arch. f. Anant. u. 
 Phys., Ph. Abt., ’14, 345; (Cited Gen. Rev., Psy. Bull., ’16.) 
 
 7 Starling, Prins. of Hum. Physiol., ’12, 228. 
 
 8 Beritoff, Ub. d. Erregungsrhythmik d. Skelettenmuskeln b. refl. Innerva¬ 
 tion, Zschr. f. Biol. 64, ’14, 161. Lucas, Keith, The Conduction of the Nerve 
 Impulse, Lond. ’17. 
 
 9 De Meyer, J. D., Des differents sources de courants electriques des systemes 
 musculaires, p. 44. Sur les courants de deformation des muscles, p. 64. De 
 la dualite d’origine des courants electriques produits par les muscles stries, 
 p. 173. Arch, internat. de physiol. 16, ’21. 
 
MECHANISM OF THE DIFFERENT TYPES 
 
 21 
 
 movements of the gross muscle, but merely as phenomena within 
 the fiber. But the work of Hill using a direct record from the 
 moving muscle (air tambour, hot wire to string galvanometer) 
 shows that the rate of c.50 per sec. does appear in the movement 
 of the member. It is difficult to imagine how the multitude of 
 minute neuro-muscular processes can be kept in phase so that 
 this rate is impressed on the mass movement, but the records are 
 very clear. However, a second and lower frequency to which 
 Hill does not call attention is very obvious in his published curves. 
 There is too little material to make a very definite calculation, 
 but apparently this lower frequency is c.io per sec. and cor¬ 
 responds to the slower frequencies emphasized by De Meyer. 10 
 
 Although nothing can be said as to the nature of this tremor 
 frequency there is good reason for assuming that it marks the 
 period of a unit of movement. Starling has shown that the 
 duration of the cycle of the muscle twitch at the ordinary tem¬ 
 perature is c. 100-180 sig., 6-10 per sec. 11 In fibrillation of the 
 muscle, a study of the continuous series of contractions shows 
 that the rate of the fibrillar cycle is 10-20 per sec. 12 This unit 
 movement appears in the various combinations which make up 
 the types of movements. 
 
 2. Slow or “Controlled” Movements. 
 
 If the movement of holding still be extended in a given direc¬ 
 tion, it is evident that the beginning of the extension will be a 
 tremor. If the attempt be to make a very small movement, the 
 extent of a tremor will determine the extent of the movement 
 which must consist of two or more tremors. The ability to make 
 movements more and more minute is not limited by sensory 
 methods of control, but by this fundamental tremor element of 
 muscular action. 13 
 
 10 Hill, A. V., Tetanic nature of the voluntary contraction in man, J. Phys., 
 
 55 , f 2 i , xiv. 
 
 11 Ibid. 
 
 12 Stevens, H. C., The cause of muscular atrophy following nerve sec. J. 
 Am. Med. Ass. 60, T8, 385. 
 
 13 Work of L. T. Anderegg and J. Merle Scott in the Oberlin laboratory 
 
22 
 
 R. H. STETSON AND JAMES A. MC DILL 
 
 When the movement is not so minute as to be limited by a 
 few tremor lengths it is still apparent that the tremor impulses 
 are present. Luciani states that a record of slow voluntary con¬ 
 traction of any muscle (e.g. the opponens of the thumb) shows 
 undulations which are fairly regular in frequency—though irregu¬ 
 lar in amplitude'—c.10-12 per sec. He quotes Griffiths’ statement 
 that an increase in frequency to 15-18 per sec. results when a 
 load is applied to the moving member. 14 
 
 Like the movement of holding still, a slow movement is due to 
 the contraction of opposing muscles. In its simplest form the 
 progress of the movement results from tremor increments in one 
 of the muscle groups. Since the movement elements occur as 
 frequently as 10 per sec. and since the increment is very slight, 
 developing little or no momentum in the moving member, the 
 movement can be changed at any movement element (tremor). 
 No neuro-muscular provision is made in advance for the control 
 of the movement. The slow movement is probably due to a series 
 of slight increases in the algebraic sum of the number of muscle 
 fibers contracting in the positive muscle group as against the 
 number of fibers contracting in the antagonistic muscle group. 
 This type of slow movement has been described and the essential 
 difference in its mechanism from that of the fast movement has 
 been discussed by Richer. 15 The sharp difference in type between 
 fast and slow movements of the eyeball has been repeatedly 
 noted. 16 
 
 3. Fast Movements. 
 
 As a slow movement is increased in speed, the movement 
 elements will be stretched out; their frequency remains the same 
 but there will be fewer undulations per unit of length. For a 
 
 shows that magnification of the visual field does not improve the delicacy of 
 minute movement. Quite as minute movements can be made without the 
 eyes as with normal vision or with magnification. 
 
 14 Ibid., 562. 
 
 15 D’Arsonval et autres, Traite de physique biologique, ’01, Tome I, 156, 
 
 16 Gertz, H., lib. d. gleitende (langsame) Augenbewegung, Zschr. f. Ps. u. 
 Ph. d. S. Abt. 2, (1 ), 49, T4, 15. Dodge, R., Psy. Rev. 7, ’00, 454. Dodge, R., 
 and Cline, T. S., Psy. Rev. 8, ’01, 155. 
 
MECHANISM OF THE DIFFERENT TYPES 
 
 23 
 
 path of given length a speed should be possible at which the 
 entire movement shall be a single stretched-out movement ele¬ 
 ment. d he movement will now be a smooth curve, a single un¬ 
 dulation. The control of the movement will depend on a single 
 impulse in the one group of muscles which starts the movement 
 and on the intervention of a second impulse in the antagonistic 
 muscle group which stops the movement (if it is a free move¬ 
 ment without obstacle, like beating a baton in the air, writing, 
 rapid shifting of the eyeball, etc.) 
 
 It is now apparent that such a rapid movement cannot be sub¬ 
 ject to control after it is once started; movement elements occur- 
 ing at the rate of 10 per sec. are the units; at most then move¬ 
 ments can be modified not oftener than ten times in a second. A 
 movement occurring at the rate of 10 per sec. and consisting there¬ 
 fore of a single movement element and terminated by the follow¬ 
 ing movement element must be the result of an adjustment pre¬ 
 ceding the entire movement. The movement at maximum rapidity 
 is controlled by a preliminary “set,” “Einstellung.” 
 
 A. Fast Movement under Tension. 
 
 If the fast movement be considered as developed from the 
 position of fixation of the moving member the movement may 
 be due to a sudden excess contraction of one of the groups of 
 muscles making up the complex of muscle groups involved in 
 holding still, followed by an excess contraction in the antagonistic 
 muscle group which stops the movement. A movement of trans¬ 
 lation is thus superimposed on the fixation, and the movement 
 occurs under tension. Not only are the muscles contracted 
 which have to do with guiding the movement (Du Bois Rey- 
 mond’s pseudantagonistic synergie) but the positive muscle group 
 and the antagonistic muscle group also maintain a tension against 
 each other throughout the movement. 
 
 B. The Ballistic Movement. 
 
 The ballistic movement is a common form of the fast move¬ 
 ment; it consists of a single unit contraction of the positive muscle 
 
24 
 
 R. H. STETSON AND JAMES A. MC DILL 
 
 group followed by a unit contraction of the antagonistic muscle 
 group. The moving member is not under tension from both 
 muscle groups; the movement of translation is not superimposed 
 on a fixation. Instead, a single tremor impulse of the positive 
 muscle group starts the movement; the contraction of this im¬ 
 pulse dies out before the second tremor impulse of the antagonistic 
 muscle group appears to check the movement. There is therefore 
 a median part of the movement in which the moving member 
 swings free carried by its own momentum. There may be fix¬ 
 ation of a joint and there is the guiding tension of muscle groups 
 which determine the path of the movement, but there is no op¬ 
 posing tension to the flight of the moving member. 17 
 
 In a to-and-fro movement at maximum speed the unit con¬ 
 traction which checks the one movement becomes the driving im¬ 
 pulse for the reverse movement, relaxing before the positive unit 
 contraction reappears to check the reverse movement and start 
 the moving member on its second flight. Such a to-and-fro move¬ 
 ment ought to approach very close to the tremor rate as indeed 
 it does. F. B. Dresslar’s observation that the maximum rate of 
 tapping is c.10.5 per sec., while the tremor rate for forearm and 
 wrist is 12.2 and 12.9 respectively should have been taken as 
 evidence that the two values are closely related and not that they 
 are due to distinct processes. 18 
 
 T. G. Brown makes the fundamental unitary mechanism to 
 consist of the efferent neurones of two antagonistic muscles. 19 It 
 is possible that the maximum rapidity of a repeated movement 
 is limited by the rate at which excitation and inhibition can be 
 developed in two antagonistic muscle groups. If one assumes 
 that inhibition is due to the combination of trains of excitation 
 in pulses in the motor nerves (K. Lucas, Verworn, etc.) it may 
 well be that the overlapping of the series to produce the con¬ 
 tinuous refractory condition followed by the normal conducting 
 condition has a definite time limit. It is probable that the me- 
 
 17 Richer, P., loc cit. 
 
 18 Some influences which affect the rapidity of voluntary movements, Am. 
 J. Psy. 4, ’91-92, 514. 
 
 19 J. Physiol. 48. 
 
MECHANISM OF THE DIFFERENT TYPES 
 
 25 
 
 chanical change due to movement is an important factor in the 
 coordination. 
 
 The fast movement under tension and the ballistic movement 
 have not always been distinguished. But in many types of skilled 
 movement the distinction is important. In piano playing, in 
 violin playing, and in telegraphy the contrast between the “tight” 
 or “stiff” rapid movement (fast movement under tension) and 
 the “loose” rapid movement (ballistic) has come to be a com¬ 
 monplace. Piano technic has been recognized during the past 
 thirty years on that basis. 
 
 At the highest rate of repetition there can still be variation 
 from movement to movement if not during the flight of any single 
 movement. Although the duration is fixed the extent of such 
 movements is subject to wide variation. This has been noted in 
 several movement studies. 20 The ballistic movement is capable 
 of the most delicate adjustment, in extent as in the case of writ¬ 
 ing and keyboard manipulation, and in force as in case of dynamic 
 shading in violin or piano playing, singing, speech, etc. 
 
 Since the duration of the rapid movement is fixed, there can 
 be but two variables, extent and force. This limits somewhat 
 the problem discussed by Morgan and Goerrig. 21 
 
 Experimental Results. 
 
 Tremors in fixation of finger—movement of holding still. 
 
 The right hand was supported on table in comfortable position. 
 A writing point, the point of a sharp needle, was fastened to the 
 
 20 Stetson, R. H., Theory of rhythm and discrete succession, Psy. Rev. 12, 
 ’05, 261. Isserlin, M., Ub. d. ablauf einfacher, willkiirlicher Bewegungen, Psy. 
 Arb. 6 (1), 1910-14, 86, who states clearly that the total duration of rapid 
 movements remains the same for a given person no matter what the extent 
 of the movement. Freeman, F. N., Anal, of the writing movement, Psy. 
 Mon. Sup. 17, T4, No. 4, 1-46, who confirms Binet and Courtier in statement 
 that in case of rapid writing movements the increase of extent of a single 
 movement, or of the writing as a whole, does not mean an increase in duration 
 of the stroke or strokes, but rather increase in speed; the time of rapid writing 
 is independent of its size. 
 
 21 Morgan, J. B., The speed and accuracy of motor adjustments, J. Xp. Psy. 
 2, T7, 225. Goerrig, M. A., Einfluss d. Zeitdauer auf d. Grossenschatzung v. 
 Armbewegung, Arch. f. d. ges. Psy. 36, T7, 293. 
 
26 
 
 R. H. STETSON AND JAMES A. MC DIED 
 
 nail of the index finger. The other fingers and thumb rested on 
 the table while this index finger was held extended with the writ¬ 
 ing point in contact with a smoked glass slide perpendicular to 
 the table, so that the finger movements were recorded in the 
 vertical plane. A Jacquet chronograph marking fifths of sec. 
 on the slide afforded a record of time intervals. The glass slide 
 was drawn in a groove by a thread winding on a kymograph drum 
 running at rather slow speed. 
 
 The records were measured under a Zeiss binocular micro¬ 
 scope. To avoid errors each change in direction was counted 
 and the result divided by two. The slides were labeled, the 
 smoked record mounted with cover glass and balsam in the usual 
 manner. 
 
 Subject W Record of 9 seconds; average per sec. 
 
 6.8 
 
 Mean variation .8 
 
 13 
 
 8.2 
 
 1. 
 
 7 
 
 8.2 
 
 1.1 
 
 8 
 
 8.1 
 
 1.1 
 
 S 
 
 7-8 
 
 i -3 
 
 10 
 
 7-7 
 
 .7 
 
 10 
 
 7-7 
 
 •9 
 
 *-r 
 
 ✓ 
 
 7-3 
 
 .8 
 
 8 
 
 6-5 
 
 •9 
 
 11 
 
 7-3 
 
 •5 
 
 4 
 
 7 - 
 
 •9 
 
 Subject A 5 
 
 74 
 
 •9 
 
 Subject N 7 
 
 8. 
 
 1.5 
 
 Subject D 5 
 
 6.9 
 
 •3 
 
 These records show a fairly definite frequency which varies 
 somewhat from sitting to sitting and from subject to subject. 
 The mode is c.7.5 per sec. which is somewhat lower than other 
 results but not significantly so. 
 
 Tremor-undulations in various types of movement at various 
 speeds: 
 
 Short, straight lines of 3-4 mm. were drawn with the ordinary 
 writing movement of fingers and hand at speeds varying from 
 14-160 per minute. 
 
 Longer lines of 440 mm. were drawn with pencil by movements 
 of the forearm and upper arm, at speeds varying from 14-160 
 per minute. 
 
MECHANISM OF THE DIFFERENT TYPES 
 
 27 
 
 The short lines of 3-4 mm. were drawn on smoked glass slides, 
 the click of a metronome indicating the beginning and end of 
 the parallel lines. There are several sources of possible variation: 
 the speed of the movement may vary, and the movement may 
 not occur within the indicated time interval. As the movements 
 are repeated and rhythmic, these variations are limited and tend 
 to compensate. The lines were measured under the microscope 
 and averaged in groups of 30. 
 
 Subject A 
 
 30 lines, 
 
 14 lines per min. 
 
 4.28 sec. per stroke, 
 
 10.1 undulations per sec. 
 
 m.v. 1.1 
 
 30 
 
 22 
 
 2.72 
 
 12.2 
 
 2.4 
 
 30 
 
 48 
 
 1.25 
 
 15-3 
 
 1.1 
 
 30 
 
 60 
 
 1. 
 
 12.3 
 
 1.6 
 
 30 
 
 70 
 
 .86 
 
 11 -7 
 
 1.4 
 
 30 
 
 80 
 
 75 
 
 11.2 
 
 i-4 
 
 30 
 
 90 
 
 .67 
 
 11.4 
 
 1 -7 
 
 30 
 
 100 
 
 .60 
 
 10.5 
 
 14 
 
 30 
 
 no 
 
 •54 
 
 9.8 
 
 2. 
 
 30 
 
 120 
 
 •50 
 
 9.8 
 
 1.8 
 
 30 
 
 130 
 
 .46 
 
 10.6 
 
 2.1 
 
 30 
 
 140 
 
 .42 
 
 11.1 
 
 2.2 
 
 30 
 
 150 
 
 .40 
 
 II -5 
 
 1-9 
 
 30 
 
 160 
 
 •37 
 
 n-3 
 
 1.8 
 
 Although there is considerable variation, it is clear that the 
 “undulation” marks some definite frequency which remains fairly 
 constant throughout the series. This tremor undulation indicates 
 some fairly constant element in the movement; it is possible that 
 the record is of impulses in the “pseudantagonistic” muscle groups 
 rather than in the driving muscles; but slow movements like that 
 of closing the fingers show that driving muscles also have the 
 same pulses. Although these movements are approximately of 
 the same length, the slowest movement has an average of 43 of 
 these elements, and the fastest movement has an average of 4. 
 
 The longer lines of 440 mm. were drawn between limiting per¬ 
 pendicular lines on smooth cardboard sheets with a hard pencil; 
 the beginning and the end of the line was indicated by metronome 
 click. In studying the lines, the sheets were placed on inclined 
 plane to bring one end nearer the eye; by “squinting” down the 
 fore-shortened line the undulations could be counted. 
 
28 
 
 R. H. STETSON AND JAMES A. MC DILL 
 
 30 lines. 
 
 Subject P 
 
 8.4 lines per min. 4.4 undulations per sec. 
 
 M.v. .9 
 
 30 
 
 14 
 
 5-6 
 
 .8 
 
 30 
 
 22 
 
 6. 
 
 
 30 
 
 42 
 
 6.9 
 
 
 30 
 
 48 
 
 79 
 
 2. 
 
 30 
 
 60 
 
 7.6 
 
 1.7 
 
 30 
 
 70 
 
 8.2 
 
 
 30 
 
 80 
 
 7-7 
 
 
 30 
 
 90 
 
 8. 
 
 
 30 
 
 100 
 
 8.2 
 
 
 30 
 
 no 
 
 8.6 
 
 
 30 
 
 120 
 
 8.3 
 
 
 30 
 
 130 
 
 77 
 
 
 30 
 
 140 
 
 8.1 
 
 
 30 
 
 150 
 
 8.1 
 
 
 30 
 
 160 
 
 8.1 
 
 2.2 
 
 There is more variation 
 
 from rate to rate than 
 
 in the record 
 
 of short lines; the mean variation at a given speed is about the 
 same as for the shorter lines. It is to be expected that the fre¬ 
 quency of the tremor-undulation would be somewhat slower when 
 larger muscles are involved; it is a familiar fact that the maximum 
 rate of larger muscles is slower. 
 
 Certain difficulties are involved in starting and stopping at a 
 limiting line when drawing lines by the above method. To avoid 
 these difficulties a series was made in which the pencil was in 
 motion when passing the limiting lines; a flying start and a flying 
 
 Subject M. 
 
 30 lines. 14 lines per min. 4.2 undulations per sec. M.v. 1.1 
 
 30 22 5.8 
 
 30 48 9-5 
 
 30 60 6. 
 
 30 70 6.2 
 
 30 80 6.8 
 
 30 90 6.8 
 
 30 100 7.8 
 
 30 no 6.9 
 
 30 120 6.2 
 
 30 130 6.8 
 
 30 140 7.3 
 
 30 150 6.8 
 
 30 160 7.2 
 
 2.4 
 
MECHANISM OF THE DIFFERENT TYPES 
 
 29 
 
 stop. A possible source of error may lie in the varying accuracy 
 with which the subject drew the pencil across the limiting lines 
 on the click of the metronome. The length of line measured was 
 300 mm.; the number of undulations was counted as before. 
 
 These records of tremor frequencies agree very well with ma¬ 
 terial previously published. But there are too few subjects for 
 the various types of movement. There are records from only 
 three for the study of tremor in fixation, records from only two 
 for the study of the longer movements, and records from only 
 one subject for the study of small movements. The results al¬ 
 though insufficient are fairly consistent and indicate a single unit 
 frequency in all sorts of movements at varying speeds. This unit 
 frequency is very close to the maximum frequency of voluntary 
 movement for the given groups of muscles. 
 
 The Termination of Skilled Movements. 
 
 The purpose of many skilled movements is achieved at the end 
 of the stroke; there the work is performed, the blow struck. 
 Although the entire path of the movement is important in the case 
 of a few movements like writing, drawing, use of surface-work¬ 
 ing tools and some phases of musical conducting, yet for such 
 movements there is always a definite termination. 
 
 The terminations of movements may be classed as follows: 
 
 1. The moving member swings loose about joint; movement 
 is terminated by ligaments and passive muscles. 
 
 2. The moving member is arrested by the antagonistic mus¬ 
 cle group. 
 
 3. The moving member is arrested by an obstacle, a “block.” 
 
 1. The form of movement in which the moving member is 
 brought to a stop by the ligaments and passive muscles is rather 
 unusual; the movement of the hand in plucking the balalaika 
 and the swing in golf are illustrations. In pitching a baseball 
 the muscles are brought into play enough to hold the arm in 
 position after the delivery but the termination of the movement 
 is due primarily to the passive tissues about the shoulder joint. 
 
 2. The moving member is brought to a stop by the antago- 
 
30 
 
 R. H. STETSON AND JAMES A. MC DILL 
 
 nistic muscle group in the “free” or self-limiting movement. 
 The movements are often executed in the air without any re¬ 
 sistance as are most gestures and the movements of the orchestra 
 conductor. All the movements of the eyeball are self-limiting. 
 Many calisthenic and athletic exercises involve such movements 
 either untrammelled or against a slight resistance. Auxiliary arm 
 movements in walking, running, and dancing are quite free. 
 Club swinging, and wand drills involve movements against a 
 slight resistance. In rowing and swimming the resistance is more 
 pronounced but the end of the movement is determined by the 
 opposing muscles. The movements of writing and drawing 
 meet a slight resistance; surface working tools involve varying 
 degrees of resistance. In speech repeated vowels and liquids re¬ 
 quire self-limiting movements of large muscles. Violin bowing 
 and the manipulation of the slide trombone involve self-limiting 
 movements against a slight resistance. In plucking the harp or 
 guitar string the movement creates a sharp, elastic resistance, re¬ 
 leases it and passes to a limit fixed by the muscles themselves. 
 
 Only a few self-limiting movements are terminated by the 
 contraction of the antagonistic muscle group acting directly 
 against the contraction of the positive muscle group. Slow move¬ 
 ments of the “controlled type,” are stopped by the increased ten¬ 
 sion of the antagonistic muscles and there is little momentum to 
 be taken up. 
 
 Wherever the movement must be delicately gauged as to point 
 in time, degree of force, or exact form of movement a fast, 
 “ballistic” movement is used; the “back stroke” and the pre¬ 
 paration for the movement may be slow and there may be long 
 pauses between “beat strokes,” but the stroke itself is a fast 
 movement. If the ballistic movement comes to rest at its ter¬ 
 mination, there is a fresh contraction of the positive muscle group 
 with other muscles involved in maintaining the position of the 
 member. Repeated movements at maximum speed show no 
 period of standstill; the end of the movement presents a remark¬ 
 ably sharp angle. The flight of the moving member initiated by 
 the positive muscle impulse meets the gradually increasing ten¬ 
 sion of the antagonistic muscle group which reverses it. The 
 
MECHANISM OF THE DIFFERENT TYPES 
 
 3i 
 
 change of direction is almost instantaneous like the rebound of 
 an ivory ball from a hard surface, or of a light weight with an 
 elastic spring. Rieger observed this rebound and referred it to 
 the positive muscle group. 22 Isserlin is right in objecting to this 
 interpretation but wrong in assuming that a pause must intervene. 
 It is quite true that in repeated fast movements there is a definite 
 “relaxation” process in the sense that the momentum of the 
 moving member must be taken up and the contraction of the 
 antagonistic muscle group developed; but in the swifter ballistic 
 movements the moving member is descending and rising without 
 pause during this “relaxation period.” 
 
 3. In a very large group of skilled movements the moving 
 member meets an obstacle, a block which stops the movement 
 without further muscular activity; whereupon in most cases the 
 antagonistic muscles presently contract and return the moving 
 member to the initial position. At medium speeds the block may 
 be said to truncate a complete movement which would swing to 
 a later termination coming to a stop with the contraction of the 
 antagonistic muscle group; instead there is a period of rest at 
 the block during which the antagonistic contraction takes place. 
 As a repeated movement to a block approaches maximum speed, 
 the pause grows less and less; finally the block becomes a mere 
 limit, the angle of reverse becomes sharp and the form of the 
 movement has become of the self-limiting type. Slow movements 
 may rest at the block and perhaps exert some pressure on the 
 block; but for the highest speed there must be no pressure what¬ 
 ever on the block. 
 
 Many of the skilled movements of musical performance are 
 against a block; piano and organ playing, fingering of strings and 
 wood wind and the brass. In piano playing rapid octaves if 
 played properly will actually exert very little pressure on the pad 
 beneath the keys. In typing and adding machine work also keys 
 are pressed down through slight resistance to a definite block. 
 Sometimes the blow is delivered to a resisting surface as in the 
 various movements of locomotion and in many of the consonant 
 
 22 Ub. Muskelzustande, Zschr. f. Ps. un. d. S. 31, 1 . 3 2 > 377 - 
 
32 
 
 R. H. STETSON AND JAMES A. MC DILL 
 
 strokes of speech. Sometimes the external resistance is elastic 
 although powerful enough to check, and even to reverse the 
 movement; leaping from a spring board, dancing on a tight rope, 
 and beating the various drums are terminations of this type. 
 
 Blocked movements, movements with and without resistance, 
 and self-limiting movements frequently occur side by side and 
 are nicely organized as in the work of an orchestra. The delicacy 
 of expression and celerity possible in methods of execution as 
 different as those of the piano, violin, harp, and voice show that 
 there may be a remarkable control of any of these forms of ter¬ 
 mination of the skilled movement. 
 
 Experimental Results. 
 
 It is easy to show that the nature of a movement is not affected 
 by the fact that it meets increased tension during a part of its 
 extent, nor by the fact that it comes up against a complete block. 
 If the increased tension is small as compared with the weight 
 of the moving member, there is no change in the curve repre¬ 
 senting the movement and it sweeps to the end without perceptible 
 change. The muscular contractions for stopping a self-limiting 
 movement and for returning the member if the movement is re¬ 
 peated are adjusted to the external tension; the form of the 
 movement is in nowise affected. 
 
 Figure i shows a movement of the hand and arm making 
 an excursion of 150-250 mm. During the lower 50 mm. of the 
 free excursion the hand strikes a platform of small mass sus¬ 
 pended by elastic bands which give a tension increasing to 150 g. 
 
MECHANISM OF THE DIFFERENT TYPES 
 
 33 
 
 at end of stroke. There is no indication of a change in the move¬ 
 ment when the hand comes in contact with the platform. 
 
 Subject blindfolded. Platform raised and lowered rapidly 
 through 60-70 mm. Tension 350 g. Points at which platform 
 is raised-and-lowered are marked 
 
 Duration of platform movement, sec. .27 
 
 .27 
 
 .22 
 
 .22 
 
 .26 
 
 .22 
 
 .20 
 
 •23 
 
 •23 
 
 •25 
 
 .21 
 
 .19 
 
 .19 
 
 .19 
 
 .20 
 
 .20 
 
 .l8 
 
 .19 
 
 .23 
 
 .24 
 
 .21 
 
 .21 
 
 .21 
 
 .23 
 
 .22 
 
 .21 
 
 .24 
 
 .24 
 
 •17 
 
 .22 
 
 .27 
 
 .28 
 
 .l8 
 
 .26 
 
 30 
 
 •25 
 
 •23 
 
 .26 
 
 Extent of platform movement, mm. 46 
 
 52* 
 
 4i 
 
 41 
 
 51* 
 
 41 
 
 36 
 
 47 
 
 50* 
 
 46 
 
 36 
 
 4i 
 
 44 
 
 41 
 50* 
 
 42 
 34 
 
 43 
 
 49 
 53* 
 40 
 
 36 
 40 
 
 56* 
 
 43 
 
 38 
 
 50 
 50* 
 
 27 
 38 
 
 53 
 
 48* 
 
 28 
 46 
 65* 
 
 38 
 
 29 
 
 37 
 
34 
 
 R. H. STETSON AND JAMES A. MC DILL 
 
 Here the change of level of the platform has been made rapidly 
 enough so that there is no readjustment. The movement dips 
 into the platform tension and goes deeper when the platform is 
 
 Duration of platform movement, sec. .31 Extent of platform movement 55 
 
 .29 
 
 51* 
 
 .27 
 
 42 
 
 .27 
 
 46 
 
 .26 
 
 40 
 
 .26 
 
 40 
 
 .26 
 
 35 
 
 .26 
 
 3i 
 
 .31 
 
 44 
 
 .37 
 
 58* 
 
 .36 
 
 46 
 
 •30 
 
 47 
 
 .22 
 
 32 
 
 .18 
 
 15 
 
 .20 
 
 31 
 
 .27 
 
 43 
 
 •25 
 
 48 
 
 .28 
 
 55* 
 
 .26 
 
 53 
 
 .27 
 
 5i 
 
 .22 
 
 45 
 
 •30 
 
 56 
 
 .27 
 
 55 
 
 .27 
 
 5i* 
 
 .27 
 
 55 
 
 .24 
 
 46 
 
 .23 
 
 49 
 
 .24 
 
 45 
 
 Change of platform level 
 
 no mm. 
 
 23 
 
 40 
 
 .22 
 
 40 
 
 .24 
 
 43 
 
 .24 
 
 45 
 
 •23 
 
 43 
 
 .23 
 
 40 
 
 •25 
 
 51* 
 
 .22 
 
 42 
 
 .23 
 
 39 
 
 .19 
 
 36 
 
 .22 
 
 41 
 
 .25 
 
 43 
 
 •23 
 
 37 
 
MECHANISM OF THE DIFFERENT TYPES 
 
 35 
 
 raised and comes back immediately to the original movement 
 form when the platform is lowered to the normal position. The 
 duration and extent records show that roughly the same speed is 
 maintained throughout. 
 
 Subject blindfolded, makes free strokes which carry down 
 the elastically suspended platform. The level of the platform is 
 raised and lowered slowly; the points where platform is at maxi¬ 
 mum height are marked Change of level 60-70 mm. Ten¬ 
 
 sion 350 g. 
 
 Where the changes of level are made gradually the tendency to 
 readjust is apparent; the movement is adjusted by the preceding 
 movement sensations, not by the sensations from the movement 
 occurring. There are many illustrations of this adjustment in 
 ordinary life: adjusting to the dimensions of the steps as one 
 climbs a staircase; adjusting to the touch of a strange piano or 
 typewriter: adjusting to a novel height of heel in walking, etc. 
 Some eighteen series of records of this sort were taken at various 
 speeds of ballistic movement; they all show the same facts as 
 those given above. The records are from but a single subject, 
 however, and need corroboration. 
 
 When the movement plays against a block, a very common 
 form of rapid stroke, if the movement is slow, the member rests 
 at the block and the curve looks precisely as if a longer self- 
 limiting movement had been truncated by the block. Series 1) 
 if completed would have been 60-70 mm. in length. The momen- 
 
36 
 
 R. H. STETSON AND JAMES A. MC DILL 
 
 turn and possibly some contraction of flexor muscles is expended 
 at this block level and the extensor contraction which is to raise 
 the arm and hand develops during this period of rest. 
 
 If the speed of the movement to the block is increased to 1.4 
 per sec. the form of the movement changes and the pointed end 
 of the movement occurs at the block, Series 2) ; there is no longer 
 a period of rest at the block. Very little energy is expended on 
 the block; the momentum developed in the moving member is 
 quickly neutralized by the extensor muscles and the moving 
 member is thrown lightly back from the block level. 
 
 ^4 7 yr- r y y \r—\r, 
 
 * V v v 1/ yzrx u. 
 
 ^ .... 
 
 Fig. 3. 
 
 If the distance from the normal level of the platform to the 
 block is small, 5-15 mm., e.g., the tendency to rest at the block is 
 more pronounced and the pause at the block is apparent in Fig. 3 
 in 1) .6 per sec., M.M 36, in 2) 1.8 per sec. M.M 108, and in 3) 
 2.1 per sec. M.M 126. But in 4) at the speed of 4 per sec. M.M 
 240 the pause has disappeared and the path of the movement 
 barely touches the block. Cf. 23 
 
 A number of records of this type from the one subject are all 
 consistent but there is need of records from more subjects. 
 
 Bearing on the Type of Movement on the Process of Learning 
 
 1. The “form” of the movement: 
 
 Wherever rapid and repeated movements are important as in 
 musical technic, use of keyboard machines, telegraphy, writing, 
 
 23 Mot. Theory of Rh. and Discrete Sue. Psy. Mon. Sup. 12, ’05, 263. 
 
MECHANISM OF THE DIFFERENT TYPES 
 
 37 
 
 and shorthand, the type of movement has been recognized as very 
 important. Keyboard work has been completely reorganized on 
 the basis of the “loose” movement which is simply a carefully 
 maintained ballistic movement of finger, hand, and forearm with 
 the use of weight of momentum as far as possible. Telegraphic 
 keys have been modified and the technic emphasized because both 
 speed and freedom from occupational neurosis depend on obtain¬ 
 ing the ballistic form. In writing it happens that a remarkable 
 piece of early work was done in the development of the ballistic 
 technic. Spencer not only developed remarkably good cursive 
 forms of the written letter, but he also achieved a technic of the 
 writing movement which gave great speed and endurance with 
 beauty of form. There are careful directions for the “muscular 
 movement,” in which the forearm slides freely and ballistically 
 about on the mass of flexor muscles and tight, cramping movements 
 of the finger and hand are avoided. Chinese and Japanese brush 
 writing and drawing have also achieved the fast, free stroke. 
 The line of Japanese painting is a free hand and free arm drawing 
 with the swift certainty of the skilled ballistic movement. The 
 bad line in drawing is the result of “controlled” movements. In 
 many of these skilled movements, piano playing, telegraphy, 
 Spencerian writing for example, the form of the movement is 
 more or less conscious and the method of training for getting the 
 technic is fairly adequate. But in many skilled processes the 
 ballistic form of the movement is the result of chance or the 
 movement goes on hampered by opposing tensions. 
 
 2. The development of speed; transition from the slow to 
 the ballistic movement; problem of the plateau of the learning 
 curve. 
 
 A few skilled movements like diving or serving at tennis must 
 be practiced at speed from the start, but most of the complicated 
 skilled movements are begun slowly and gradually increased in 
 speed. Mistakes in the precise path of the movement are usually 
 counted lapses in “accuracy.” These are kept to a minimum and 
 constantly corrected while the movement is repeated at higher and 
 higher speed. This is the great feature of the process called 
 
38 
 
 R. H. STETSON AND JAMES A. MC DILL 
 
 training or “development of skill.” It is usually assumed that 
 the movement is being stereotyped, ground in by repetition, and 
 that the increase of speed is merely a matter of gradually in¬ 
 creasing the tempo while the movement remains the same. First 
 get the path of the movement accurately and then gradually speed 
 up until you reach the normal tempo. On the assumption that it 
 is one and the same movement process at the different speeds it 
 has always been something of a puzzle that the learning curve 
 fails to show a regular increase in speed Instead of a gradual 
 and regular increase, the curve shows rather rapid gains at points 
 with long periods of practice between during which there is no 
 apparent gain at all. There are various explanations: periods of 
 assimilation in which recent gains are being consolidated; com¬ 
 pensation between improvement and fatigue, etc. The funda¬ 
 mental fact is that the movement itself changes with the increase 
 in speed; it is not the same movement throughout training. Be¬ 
 ginning as a slow process composed of many movement elements 
 and with frequent pauses, the increasing speed means that fewer 
 movement elements must take the place of the many. The path 
 of the movement has not changed but a process which included 
 twenty movements, and might be stopped at twenty different 
 places and may have paused at many of them, is now reduced to 
 fifteen, to seven, to three. In reality passing from slow to rapid 
 is a matter of substituting a single movement for several move¬ 
 ments over the same path. Nothing else can happen; if about ten 
 movement elements per second is the maximum, a given move¬ 
 ment beginning with ten movement elements must be reduced to 
 less than ten movement elements when the speed exceeds one per 
 second. If the given movement takes place at the rate of two 
 per second the original ten movement elements must be reduced 
 to at most five. When the beginner prints a character at the type¬ 
 writer he first puts his finger on the key, and then presses it down; 
 later the placing and striking must become one stroke. In many 
 cases different groups of muscles are employed for the slow and 
 the rapid movements; the movements are different in every sense, 
 they consist of different numbers of grouped movement elements 
 
MECHANISM OF THE DIFFERENT TYPES 
 
 39 
 
 executed by different muscle groups. And this fact must have an 
 important influence on the learning curve. When the “form” of 
 the movement is stable, when the number and grouping of the 
 movement elements is no longer changing, the increase in speed 
 is very slow indeed but is gradual—as at the end of training 
 when the subject comes very slowly to his maximum efficiency. 
 It is perhaps due to gradual nutrition changes (“development” 
 of muscles) and to the refinement of the cues and adjustments 
 which direct the movement. But during a large part of the ob¬ 
 vious and relatively rapid improvement, the “form” of the move¬ 
 ment, the actual movement-process is subject to change. When 
 a new and more condensed group of movement elements is sub¬ 
 stituted for the more detailed and segmented group there is a 
 very rapid increase in speed. But these new “forms” of move¬ 
 ment, these new combinations of the individual units are blun¬ 
 dered into. During the plateau the subject is repeating the move¬ 
 ment verbatim until chance gives a better way and he falls into 
 a better “form.” “Plunging” at the expense of mistakes has its 
 advantages for thereby the subject comes to new and more rapid 
 “forms” for covering the same movement path. The advantage 
 of ensemble playing for the beginner in music is that it forces 
 him to try things at a speed which compels new combinations, 
 with approximate accuracy in the main movements at least. 
 Mere repetition does not constitute fruitful practice; changes in 
 the type of movement used are essential. 
 
 Summary 
 
 Movements may be classed as i. movement of holding still 
 —fixation, 2. slow movement, 3. fast movements, A. with ten¬ 
 sion, B. Ballistic. The difference between these classes is due 
 to the number of movement elements in each type of movement. 
 The movement elements are equivalent to the tremor undulations. 
 In fixation a number of muscle groups contract against each other 
 and the tremor is the only change of position. In the slow move¬ 
 ment there are a large number of movement elements per unit 
 of length and the movement can apparently be changed at any 
 
40 
 
 R. H. STETSON AND JAMES A. MC DILL 
 
 point in its course; it is “controlled.” In the fast movement there 
 are few elements, only a few changes are possible; at the maximum 
 rate when each stroke consists of but one element, no change 
 during the course of the movement is possible. In the fast move¬ 
 ment under tension the movement of translation is superimposed 
 on a movement of fixation. In the ballistic movement there is 
 a minimum muscle contraction during the flight of the move¬ 
 ment. A single impulse of the positive muscle group starts a 
 very rapid movement; during the earlier course of the movement 
 this impulse ceases and the moving member swings free to the 
 termination of the movement. Such a ballistic movement will 
 have a duration independent of the extent of the stroke; long or 
 short, the movement can be repeated at a maximum rate which 
 approaches the tremor frequency of the groups of muscles in¬ 
 volved. 
 
 There are three common forms for the termination of a move¬ 
 ment: i. the moving member swings loose and is arrested by 
 ligaments and passive muscles, 2. the moving member is ar¬ 
 rested by the contraction of the antagonistic muscle group, 3. the 
 moving member is arrested by an obstacle. The first form is less 
 usual; the second is the common type or “free” or self-limiting 
 movement; the third is very common in all sorts of rapid ma¬ 
 nipulation of mechanical apparatus. When the movement ter¬ 
 minating at an obstacle occurs at maximum speed it tends to be¬ 
 come self-limiting. 
 
 In training the type of the movement changes from slow to 
 ballistic although the path of the movement does not change. 
 Plateaux in the learning curve are due to periods in which the 
 movement is repeated without change of type and therefore at 
 the same speed. Devices in training are important which lead 
 to the development of new “forms” of the movement. 
 
MEASUREMENTS OF RHYTHMIC UNIT-GROUPS AT 
 
 DIFFERENT TEMPOS 
 
 R. H. Stetson and T. E. Tuthill 
 
 The fundamental groups of a rhythmic series consist of ac¬ 
 cented and unaccented beats. In musical notation it has been 
 customary to give these beats a strictly quantitative expression. 
 It is assumed in musical instruction and occasionally in psycho¬ 
 logical theory that the quantitative temporal relations are an 
 essential factor in the unit-group. 
 
 The iamb or “dotted-eighth-sixteenth” figure was chosen as 
 one of the simplest and most obvious unit-groups with a pro¬ 
 nounced difference in the length of the elements and a very 
 definite accent. The question was raised: Is the musical iamb 
 actually played in a fixed temporal form as indicated by the mu¬ 
 sical notation? The commonest form of the iamb was chosen 
 and a half dozen trained musicians were asked to play this 
 rhythm at different tempos; the records were carefully measured. 
 The form that the musicians were asked to play was always a 
 simple phrase: 
 
 The rhythms were tapped on a key which gave a clear sound like 
 that of the Vergil clavier with which all the subjects were fa¬ 
 miliar. The beats were recorded on a carefully controlled kymo¬ 
 graph drum. The subjects were all accustomed to ensemble 
 playing, were considered accurate in rhythm, and were all aware 
 that the “accuracy” of their rhythms was to be tested. They did 
 their best to make the form correct as they conceived it. 
 
 The following tables show a sample of the actual measurements 
 in one case and of the computed averages and mean variations for 
 the series of readings of the records of each of the six subjects. 
 
 Records of doublets and triplets (trochees and dactyls) have 
 been added for comparison. 
 
 41 
 
42 
 
 R. H. STETSON AND T. E. TUTH 1 LL 
 
 TABLE I 
 
 Subject W. 
 
 Iambs 
 
 Readings in tenths of millimeter from kymograph drum. 
 
 Metronome rate 50 
 
 50 
 
 
 80 
 
 
 100 
 
 
 120 
 
 
 
 js 
 
 
 I s 1 
 
 * N 
 
 
 
 
 
 1 
 
 0 * 
 
 e i 
 
 J. J 
 
 S d. 
 
 i 
 
 J' 4 . 
 
 
 173 
 
 561 
 
 315 
 
 840 
 
 137 
 
 410 
 
 170 
 
 706 
 
 168 
 
 526 
 
 285 
 
 755 
 
 125 
 
 370 
 
 167 
 
 683 
 
 
 
 306 
 
 764 
 
 132 
 
 4 i 5 
 
 172 
 
 682 
 
 168 
 
 506 
 
 292 
 
 765 
 
 120 
 
 405 
 
 172 
 
 6 77 
 
 175 
 
 490 
 
 292 
 
 700 
 
 127 
 
 377 
 
 170 
 
 631 
 
 
 
 307 
 
 663 
 
 120 
 
 416 
 
 160 
 
 630 
 
 251 
 
 830 
 
 278 
 
 674 
 
 
 
 148 
 
 681 
 
 262 
 
 830 
 
 280 
 
 666 
 
 147 
 
 460 
 
 158 
 
 690 
 
 242 
 
 796 
 
 234 
 
 570 
 
 148 
 
 442 
 
 170 
 
 665 
 
 
 
 240 
 
 640 
 
 136 
 
 477 
 
 147 
 
 676 
 
 213 
 
 702 
 
 233 
 
 617 
 
 152 
 
 476 
 
 145 
 
 650 
 
 240 
 
 762 
 
 237 
 
 616 
 
 170 
 
 485 
 
 160 
 
 668 
 
 240 
 
 730 
 
 230 
 
 634 
 
 167 
 
 475 
 
 154 
 
 650 
 
 
 
 
 
 160 
 
 496 
 
 152 
 
 640 
 
 
 
 315 
 
 849 
 
 
 
 158 
 
 650 
 
 
 
 313 
 
 810 
 
 175 
 
 450 
 
 160 
 
 663 
 
 
 
 321 
 
 807 
 
 503 
 
 184 
 
 170 
 
 650 
 
 
 
 
 
 182 
 
 488 
 
 
 
 
 
 
 
 196 
 
 503 
 
 
 
 
 
 
 
 170 
 
 5 io 
 
 
 
 of the 
 
 short 
 
 note to 
 
 the long 
 
 note: 
 
 
 
 
 100 
 
 120 
 
 M.M. 50 80 
 
 Theoretical ratio, assuming that the iamb is a quantitative expression 
 
 250 750 
 
 250750 
 
 
 250 750 
 
 
 250750 
 
 
 
 W. 240 760 
 
 mv 30 284716 mv 30 
 
 252 748 1 
 
 mv 10 
 
 190:810 
 
 mv 10 
 
 
 Subject W 
 
 
 
 
 
 
 
 
 M.M. 40 
 
 80 
 
 120 
 
 
 160 
 
 
 180 
 
 
 180 400 
 
 135 400 
 
 160 
 
 400 
 
 145 
 
 280 
 
 140 
 
 235 
 
 180 500 
 
 170 390 
 
 165 
 
 400 
 
 140 
 
 260 
 
 130 
 
 220 
 
 195 5 io 
 
 165 520 
 
 170 
 
 420 
 
 130 
 
 290 
 
 120 
 
 215 
 
 180 470 
 
 200 500 
 
 170 
 
 420 
 
 135 
 
 300 
 
 120 
 
 215 
 
 
 190 510 
 
 
 
 
 
 145 
 
 225 
 
 Averages: 
 
 
 
 
 
 
 
 
 Theoret. 
 
 
 
 
 
 
 
 
 250750 
 
 250750 
 
 250 750 
 
 250750 
 
 250 750 
 
 W. 275 725 mv 
 
 7 268 732 mv 27 
 
 290 
 
 710 mv 6 
 
 323 1677 mv 13 
 
 366 1634 mv 
 
MEASUREMENTS OF RHYTHMIC UNIT-GROUPS 
 
 43 
 
 At the slower tempos M.M. 50 and 80 many of the individual 
 figures are far enough from the theoretical ratio so that the dif¬ 
 ference could easily be detected by the ear. The average values 
 are not far enough from the theoretical ratio so that the difference 
 could be detected by the ear. The average at M.M. 120 is far 
 enough from the theoretical ratio to be at the threshold of dis¬ 
 crimination, 40-66 sigma. It is to be noted that at none of the 
 tempos do the values vary about the theoretical ratio as a norm. 
 
 In the second series from the subject W. it is to be noted that 
 the forms do not agree with other records from the same sub¬ 
 ject, save in having the short note in general longer than the 
 theoretical value. 
 
 TABLE II 
 
 Subject M 
 
 Averages of readings expressed as ratios 
 
 M.M. 40 
 
 M. 346:654 av. 14 rdgs mv 59 
 Theoret. 
 
 250 750 
 
 M.M. 100 
 
 M. 294:706 av. 17 rdgs, mv 12 
 M.M. 140 
 
 M. 285:715 av. 14 rdgs, mv 11 
 
 80 
 
 312:688 av. 11 rdgs, mv 12. 
 
 250 750 
 
 120 
 
 267723 av. 15 rdgs, mv 13 
 180 
 
 326:674 av. 20 rdgs, mv 13. 
 
 TABLE III 
 
 Subject D 
 
 Iamb 
 
 Averages of readings expressed as ratios 
 
 M.M. 40 
 
 
 80 
 
 
 
 D. 331 =669 av. 7 rdgs, 
 
 mv 16 
 
 366 :634 
 
 av. 9 rdgs, mv 
 
 15 
 
 283717 5 
 
 4 
 
 354 =646 
 
 8 
 
 14 
 
 Theoret. 
 
 
 
 
 
 250:750 
 
 
 250 750 
 
 
 
 M.M. 120 
 
 
 160 
 
 
 
 D. 315:685 av. 8 rdgs, 
 
 mv 6 
 
 316 :684 
 
 av. 7 rdgs, mv 
 
 9 
 
 335 :665 5 
 
 
 316 :684 
 
 7 
 
 13 
 
 Theoret. 
 
 
 
 
 
 250 750 
 
 
 250 750 
 
 
 
44 
 
 R. H. STETSON AND T. E. TUTHILL 
 
 In Table II the individual unit-groups show values at all tempos 
 which could easily be discriminated by the ear from the theoretical 
 ratio. In the case of M.M. 40 and 80 the average of the readings 
 is so unlike the theoretical ratio that the difference would be ob¬ 
 vious to the ear. As often, the mean variation shows greater 
 irregularity at the slow tempos. 
 
 The divergencies from the theoretical ratio at the lower tempos 
 as shown in Table III are pronounced and would be obvious to 
 the ear. 
 
 TABLE IV 
 
 Subject H 
 Iamb 
 
 Averages of readings expressed as ratios 
 
 M.M. 40 
 
 
 
 80 
 
 
 H. 400:600 av. 
 
 10 rdgs, mv 
 
 24 
 
 393 :6o 7 av. 8 rdgs, mv 8 
 
 
 3701630 
 
 8 
 
 22 
 
 373:627 10 
 
 26 
 
 3621638 
 
 10 
 
 4 
 
 353:647 8 
 
 14 
 
 Theoret. 
 
 
 
 
 
 250 750 
 
 
 
 250 750 
 
 
 M.M. 120 
 
 
 
 160 
 
 
 H. 364:636 av. 
 
 11 rdgs, mv 47 
 
 366:634 av. 10 rdgs, mv 26 
 
 
 335 :665 
 
 10 
 
 17 
 
 330:670 6 
 
 10 
 
 330:6;o 
 
 7 
 
 16 
 
 354:646 7 
 
 7 
 
 Theoret. 
 
 
 
 
 
 250750 
 
 
 
 250 750 
 
 
 M.M. 200 
 
 
 
 
 
 H. 354:646 av. 
 
 9 rdgs 18 
 
 
 
 
 360:640 av. 
 
 14 rdgs 14 
 
 
 
 
 344:656 av. 
 
 7 rdgs 34 
 
 
 
 
 Theoret. 
 
 250 750 
 
 At all tempos in all three records in Table IV, the short note 
 of the unit-group is much longer than the theoretical value, and 
 as a rule is longer than that given by other subjects. In nearly 
 every case the individual unit-group as played could be discrimi¬ 
 nated by ear from a figure played with the theoretical values. 
 
 The type used by the subject is very definite; there is little 
 variation at any tempo. 
 
MEASUREMENTS OF RHYTHMIC UNIT-GROUPS 
 
 45 
 
 TABLE V 
 
 Subject P 
 
 Iamb 
 
 Averages of readings expressed as ratios 
 
 M.M. 40 
 
 
 80 
 
 
 
 P. 3 2 5 :675 av. 
 
 4 rdgs. mv 13 
 
 318 1682 
 
 av. 8 rdgs, 
 
 mv 9 
 
 3 d 2 :675 
 
 4 10 
 
 240 760 
 
 8 
 
 14 
 
 263 737 
 
 4 8 
 
 251 749 
 
 5 
 
 12 
 
 348 =652 
 
 5 7 
 
 222 778 
 
 3 
 
 0 
 
 Theoret. 
 
 
 
 
 
 250750 
 
 
 250 750 
 
 
 
 M.M. 120 
 
 
 160 
 
 
 
 P. 283 717 av. 
 
 4 rdgs, mv 0 
 
 362 :63s 
 
 av. 4 rdgs, 
 
 mv 33 
 
 303 :697 
 
 6 10 
 
 299:7c1 
 
 6 
 
 18 
 
 308 1692 
 
 5 6 
 
 325 :675 
 
 5 
 
 30 
 
 246 754 
 
 4 0 
 
 276 724 
 
 3 
 
 0 
 
 Theoret. 
 
 
 
 
 
 250 750 
 
 
 250:750 
 
 
 
 The number of readings recorded in Table V is rather small. 
 
 TABLE VI 
 
 Subject S 
 
 Iamb 
 
 Averages of readings expressed as 
 M.M. 40 
 
 S. 262 738 av. 6 rdgs, mv 18 
 Theoret. 
 
 250:750 
 
 M.M. 100 
 
 S. 366:634 av. 10 rdgs, mv 18 
 Theoret. 
 
 250 750 
 
 ratios 
 
 80 
 
 352:648 av. 11 rdgs, mv 10 
 250:750 
 
 120 
 
 325 :675 av. 12 r< fgs, mv 6 
 250 750 
 
 M.M. 140 160 
 
 S 380:620 av. 12 rdgs, mv. 20 400:600 av. 12 rdgs, mv. 24 
 
 Theoret. 
 
 250 750 250 750 
 
 Iamb at tempos which increase by small intervals. Mean 
 variation as usual. 
 
46 
 
 R. H. STETSON AND T. E. TUTHILL 
 
 M.M. 40 
 
 50 
 
 60 
 
 
 72 
 
 
 359:641 av. 10 rdgs 
 
 
 249751 av. 
 
 10 rdgs 
 
 
 
 360 -.640 10 
 
 409:591 av. 10 rdgs 
 
 457:543 
 
 10 
 
 375:625 av. 
 
 10 rdgs 
 
 317:683 10 
 
 348:652 10 
 
 361:639 
 
 10 
 
 409: 59 i 
 
 10 
 
 Theoret. 
 
 
 355 :645 
 
 10 
 
 332:668 
 
 10 
 
 250 750 
 
 250 750 
 
 250 750 
 
 
 250:750 
 
 
 M.M. 84 
 
 96 
 
 108 
 
 
 112 
 
 
 351:649 av. 10 
 
 323:677 av. 10 rdgs 
 
 409,591 av. 
 
 10 rdgs 
 
 364:656 av. 
 
 10 rdgs 
 
 336:664 10 
 
 390:610 10 
 
 376:624 
 
 10 
 
 
 
 Theoret. 
 
 388:612 10 
 
 350 1650 
 
 10 
 
 
 
 250 750 
 
 250 750 
 
 250 750 
 
 
 
 
 M.M. 126 140 
 
 340:660 av. 10 rdgs 348:652 av. 10 rdgs 
 
 250:750 250:750 
 
 In the records of Table VI the short note of the unit-group is 
 longer than the theoretical value; this is in accord with the records 
 of other subjects. In the case of the slower tempos and occasion¬ 
 ally at the higher tempos, the difference is large enough to be 
 easily recognized by the ear. 
 
 It is apparent that the type of iamb may change, not only 
 from subject to subject, but from time to time with the same 
 subject; though the coordination is maintained when once estab¬ 
 lished. For example in Table VI at M.M. 40, the type 260:740 
 is decidedly different from the type 360:640. So also at M.M. 
 60, type 250:750, type 460:540, and type 350:650 are decidedly 
 different. The variation within each of such a series is slight, 
 showing that the averages are not accidental. 
 
 Table VII shows the usual variations. M.M. 40 there are two 
 types of iamb apparent, type 240:760, and type c.340:660. All 
 the other figures £re fairly uniform. With the exception of the 
 single case just mentioned at M.M. 40, the averages show a type 
 in which the short note is longer than the theoretical value. 
 
MEASUREMENTS OF RHYTHMIC UNIT-GROUPS 
 
 47 
 
 TABLE VII 
 
 Subject T 
 
 Iamb 
 
 Average of readings expressed as ratios 
 
 M.M. 40 60 
 
 243 757 av. 11 rdgs, mv. 14 340:660 av. 
 3581642 10 
 
 369:581 10 
 
 3001700 6 
 
 329:671 10 
 
 343:657 7 
 
 313:687 9 
 
 331 :66g 10 
 
 Theoret. 
 
 250 750 
 
 80 
 
 13 rdgs, mv. 27 248:752 av. 13 rdgs, mv. 12 
 
 242 758 10 
 
 299 701 10 
 
 313:687 10 
 
 2 76 724 8 
 
 357:643 9 
 
 250750 
 
 M.M. 100 
 
 120 
 
 
 272728 av. 13 rdgs, mv. 9 
 
 300700 av. 
 
 11 rdgs, mv. 6 
 
 
 283:711 
 
 10 
 
 
 317:683 
 
 10 
 
 
 290:710 
 
 10 
 
 
 284716 
 
 10 
 
 
 287713 
 
 11 
 
 
 320:68o 
 
 10 
 
 Theoret 
 
 309:691 
 
 9 
 
 250 750 
 
 250 750 
 
 
 M.M. 140 
 
 160 
 
 
 342:658 av. 12 rdgs, mv. 27 
 
 294 706 
 
 av. 10 rdgs, mv. 18 
 
 
 314:686 
 
 10 
 
 
 347 :653 
 
 10 
 
 
 352 :648 
 
 10 
 
 
 385: 6 i 5 
 
 10 
 
 
 331 -.669 
 
 10 
 
 Theoret. 
 
 327:673 
 
 10 
 
 250 750 
 
 250 750 
 
 
4 8 
 
 R. H. STETSON AND T. E. TUTHILL 
 
 TABLE 
 
 Subject H 
 
 Trochee doublet ( " 
 
 " 1 ) 
 
 
 1 
 
 # 
 
 j 
 
 0 
 
 
 > 
 
 
 
 MM. 40 
 
 
 80 
 
 513:487 av. 8 rdgs, mv. 15 
 
 525 
 
 518:482 4 
 
 
 502 
 
 Theoret 
 
 
 
 500:500 
 
 
 500 
 
 M.M. 120 
 
 
 160 
 
 509:481 av. 11 
 
 rdgs, mv. 9 
 
 440 
 
 515:485 8 
 
 
 505 
 
 Theoret. 
 
 
 
 500:500 
 
 
 500: 
 
 Subject S 
 
 Trochee, doublet ( 1" 
 
 1 
 
 n> 
 
 
 1 
 
 # 
 
 
 >■ 
 
 
 
 M.M. 80 
 
 
 100 
 
 580:420 av. 16 
 
 rdgs, mv. 17 
 
 540 
 
 Theoret: 
 
 
 
 500:500 
 
 
 500 
 
 M.M. 120 
 
 
 140 
 
 509:491 av. 14 
 
 rdgs 
 
 515 ' 
 
 Theoret 
 
 
 
 500:500 
 
 
 
 Subject W 
 
 Trochee, doublet ( j‘ 
 
 “I) 
 
 
 J 
 
 1 
 
 & 
 
 
 
 
 
 M.M. 40 
 
 
 80 
 
 512:488 av. 5 rdgs, mv 15 
 
 507: 
 
 Theoret. 
 
 
 
 500:500 
 
 
 500: 
 
 M.M. 120 
 
 
 140 
 
 504:496 av. 16 rdgs 
 
 529: 
 
 VIII 
 
 1475 av. 7 rdgs, mv. 19 
 1498 9 
 
 : 5 °° 
 
 200 
 
 :560 av. 10 rdgs 507 1493 av. 10 rdgs 
 :495 9 
 
 1500 500:500 
 
 1460 av. 10 rdgs 
 
 :50O 
 
 1485 av. 14 rdgs 
 500:500 
 
 100 
 
 493, av. 8 rdgs, mv. 20 515:485, av. 14 
 
 500 500:500 
 
 471 av. 20 rdgs 
 
 In all the trochees of Table VIII the accented note is length¬ 
 ened. This lengthening of the accented note has been frequently 
 reported. The doublet does not vary as much from the theoretical 
 
MEASUREMENTS OF RHYTHMIC UNIT-GROUPS 
 
 49 
 
 value as does the iamb. The variation from tempo to tempo and 
 from sitting to sitting is probably due to the amount of accent 
 thrown on the first note of the doublet; it is well known that an 
 increase in the accent increases the length of the accented note. 
 
 TABLE IX 
 
 Subject S 
 
 Dactyl, triplet 
 
 rr 
 
 © © © 
 
 3 
 
 ) 
 
 M.M. 40 
 
 478:262:259 av. 7 rdgs, mv. 15 
 Theoret. 
 
 333 : 333 :333 
 M.M. 100 
 
 343:326:329 av. 7 rdgs, mv. 14 
 
 80 
 
 388:315:296 av. 7 rdgs, mv. 12 
 
 333 : 333 : 333 
 120 
 
 343:328:329 av. 7 rdgs, mv. 16 
 
 Theoret. 
 
 333 : 333 '333 333 1333 :333 
 
 M.M. 140 
 
 345 : 334:321 av. 7 rdgs, mv 8 
 Theoret. 
 
 333 : 333 :333 
 
 Subject W. 
 
 M.M. 40 
 
 374:359:269 av. 4 rdgs, mv. 6 
 Theoret. 
 
 333 - 333 :333 
 M.M. 100 
 
 336:328:335 av. 5 rdgs, mv. n 
 Theoret. 
 
 333 '- 333 :333 
 
 M.M. 140 
 
 352:318:330 av. 4 rdgs, mv. 12 
 Theoret. 
 
 333 : 333 :333 
 
 80 
 
 344 : 335:321 av. 7 rdgs, mv. 5 
 
 333 : 333 :333 
 120 
 
 341:333:326 av. 14 rdgs, mv. 11 
 333 - 333 :333 
 
 Like the trochees, these dactyls of Table IX show the lengthen¬ 
 ing of the accented note. It is much more pronounced in some 
 cases. The type is fairly well maintained in a given trial, as the 
 mean variations show. 
 
50 
 
 R. H. STETSON AND T. E. TUTHILL 
 
 Discussion of Results 
 
 It is rare indeed that the actual temporal relations of a musical 
 iamb of the dotted-eighth-sixteenth form correspond at any 
 tempo to the ‘'theoretical value” of the notation. Not only do 
 the individual unit-groups differ from this theoretical ratio, but 
 the averages do not vary about this ratio as a norm. Only six 
 series, involving sixty-one readings, out of seventy one series, 
 involving one thousand fifty-two readings, show values near the 
 theoretical value. These series whose averages are near the 
 supposed norm are not to be found at any particular tempo, nor 
 with any particular subject; they are infrequent and accidental. 
 
 In general the unaccented note of the iamb is decidedly longer 
 than the theoretical value at all tempos and with all subjects. The 
 type of the unit-group at a given tempo for a given sitting is 
 fairly constant, as the mean variations show; but the type varies 
 widely not only from subject to subject and from tempo to tempo, 
 but also from sitting to sitting at the same tempo with the same 
 subject. 
 
 The records of triplets and doublets show the usual lengthening 
 of the accented note, when compared with the theoretical value. 
 In the case of the iamb however the “lengthening” of the short 
 unaccented note cannot be attributed to accent. 
 
 The results tend to show that the groupings of the fundamental 
 rhythmic unit-groups are not a matter of quantitative time di¬ 
 vision; the sense of rhythm cannot be explained in terms of 
 judgment of time intervals. Professionally trained subjects are 
 unable to achieve the theoretical ratios. The types are much too 
 variable; with these six musicians the records show time divisions 
 for the dotted-eighth-sixteenth unit-group which vary all the way 
 from the theoretical ratio i 13 through 1 :2 to 2 -.3 and there is no 
 preference for some simple ratio. 
 
 On the other hand, the grouping is not the random placing of 
 some short before a long so that “the ‘attention’ subordinates the 
 minor to the major element.” The small variations show a pre¬ 
 cise movement type for each sitting. Some process makes the 
 division fairly exact for each sitting. 
 
MEASUREMENTS OF RHYTHMIC UNIT-GROUPS 
 
 5i 
 
 The conception of a rhythmic unit-group as an organized 
 group of movements whose conditions are muscular comes nearer 
 to fitting the facts. It is quite possible to establish a coordination 
 involving particular muscles and a particular stress on the ac¬ 
 cented beat which shall give precise movements during a single 
 sitting. Since the movements are precise their time intervals are 
 also fixed and regular. Changes of stress and of muscle group 
 alter the type of unit-group. The limits of the variation of short 
 and long in the musical iamb are the limits of the possible co¬ 
 ordinations which give a satisfactory grouping of a light short 
 pulse and a following heavy pulse into a single movement cycle. 
 
THE APPLICATION OF THE BINET-SIMON TESTS TO 
 GROUPS OF WHITE AND COLORED 
 SCHOOL CHILDREN* 
 
 George R. Wells 
 
 It has seemed to the writer that Oberlin offers a very fine op¬ 
 portunity to test the relative mental abilities of white and colored 
 children. There is a fairly large number of colored children in 
 the public schools of Oberlin, large enough to give some signifi¬ 
 cance to a comparative test. The not unimportant part which 
 Oberlin as a community and as a college has historically taken 
 in the emancipation propaganda attracted many colored residents 
 both before and after the war, a species of selection probably 
 operating to choose the more intelligent and energetic members 
 of the race. And the influences which attracted them were more 
 or less effective to make the negroes welcome when they settled 
 here, and to some extent, are still effective in the same way. 
 
 It has come about that at the present time colored residents 
 are less set apart from white people than in most communities. 
 The social environments of the two races are not as different as 
 in practically all southern and most northern towns. The mem¬ 
 bers of both races attend school, church and college on exactly 
 the same terms. Of course this does not mean that the social 
 environment of a colored family is identical with that of the aver¬ 
 age white family. But if the conditions for testing racial mental 
 characteristics are not entirely free from the disturbances of en¬ 
 vironmental variations, they are perhaps as nearly free as we are 
 apt to find anywhere in the country. 
 
 During the spring of 1914 an investigation was made of the 
 relative mentality of the white and colored pupils in the public 
 schools of Oberlin. In this investigation the writer was assisted 
 by a group of his students from the Psychological Laboratory of 
 
 * The above article was written in 1915. 
 
 52 
 
APPLICATION OF THE BINET-SIMON TESTS 
 
 53 
 
 Oberlin College and by three members of the senior class of the 
 Oberlin Kindergarten Training School, to all of whom acknowl¬ 
 edgment is hereby made. 
 
 The tests applied were the ordinary Binet-Simon series. The 
 form of test used was Huey's edition of Goddard’s revision of the 
 1911 scale, as listed in the forms published by Warwick and York. 
 The investigation was officially recognized by Superintendent 
 Rawdon of the Oberlin Public School system. A room was placed 
 at the disposal of the examiners at each of the three schools, and 
 the pupils were sent from their class rooms to these examining- 
 rooms one by one. By this and other means it was possible to make 
 the tests with very little distraction 
 
 Several problems of procedure arose early in the investigation. 
 The period of testing covered several weeks, and, in spite of 
 directions to the contrary, there is reason to believe that there was 
 some little discussion of the tests among the pupils. There are 
 two possible means of lessening, though not of eliminating, the 
 effect of such discussion, assuming that it existed. In the first 
 place, alternative questions could be, and were, used to some ex¬ 
 tent. But the limit of this method was soon reached. More to 
 the point was the carefully carried out practice of having the 
 tests on whites and blacks go on at the same time. White and 
 colored children were examined in haphazard order. So that if 
 any effect was produced by the conversation among the children 
 concerning the tests there is no reason to suppose that it influenced 
 one race more than another. The comparative value of the tests 
 is certainly not affected by this influence. 
 
 Again it was found early in the tests that there was difficulty 
 in the application of the fifteen year old test. For if a child 
 passes the twelve year old test and fails in the fifteen year test 
 there is some room for doubt as to how he should be classified. 
 If there were thirteen or fourteen year tests the child might pass 
 one or both of them. It is evident, I think, that mental age above 
 twelve years can’t be measured by the Binet-Simon scale. The 
 following rules were adhered to in the calculation of the mental 
 age after the tests has been administered. 
 
54 
 
 GEORGE R. WELLS 
 
 1. All tests “over fifteen” were entirely neglected. 
 
 2. When the mental age of any child proved to be above 
 twelve, no matter what his actual age, the card record of that 
 case was discarded, and that record does not enter into the final 
 results. 
 
 3. All cases of over twelve years actual age were likewise 
 neglected unless the child failed in either the twelve year or in 
 the eleven year tests. 
 
 4. If a child over twelve years actual age failed in the eleven 
 or in the twelve year tests, the fifteen year tests were given. If 
 successfully passed these counted as one additional year, or re¬ 
 spective fraction thereof. But if the addition of this year made 
 the mental age over twelve the card was thrown out as above 
 stated. 
 
 5. No children under six years were included in the tests. 
 The calculations of mental age were made by the writer and not 
 in any case by the students engaged in making the tests. 
 
 Practically all white and colored children in the Oberlin Pub¬ 
 lic Schools from six to twelve years of mental age were tested. 
 The numbers actually recorded in the tables below, after eliminat¬ 
 ing all those affected by the rules just mentioned, were 96 negroes 
 and 267 whites, the total number tested must have been half as 
 many again. 
 
 In the following tables the figures represent percentages of the 
 number of individuals involved, rather than actual numbers. 
 This is done so that the difference in number of negroes and 
 whites may be equalized. But for purposes of simplification one 
 negro is counted as one percent of the total number of negroes 
 instead of 1/96 of one percent, which is the strictly accurate 
 figure. Likewise in the case of the whites concerned one case 
 counts for 4/11 of one percent. As there are 267 whites con¬ 
 cerned the absolutely correct figure would be 100/267 of one per 
 cent, a rather unwieldly figure. 
 
 Table No. 1 shows the distribution of advancements and re¬ 
 tardations for from six to twelve years mental age, with some 
 cases running as high as sixteen years of actual age. The table 
 
RETARDED 
 
 TABLE I 
 
ADVANCED RETARDED 
 
 TABLE II 
 
 
 6 
 
 W 
 
 X 
 
 7 
 
 W 
 
 N 
 
 8 
 
 W 
 
 N 
 
 W 
 
 ) 
 
 N 
 
 10 
 
 w 
 
 N 
 
 11 
 
 W 
 
 X.' 
 
 12 
 
 w 
 
 N 
 
 13 
 
 W N 
 
 14 
 
 W X 
 
 15 
 
 W X 
 
 16 
 
 W X 
 
 3 to 4 years 
 
 
 
 Vu 
 
 
 
 
 7j 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2 to 3 years 
 
 
 
 l7ii 
 
 1 
 
 i7« 
 
 
 1% 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 to 2 years 
 
 4 / 
 
 / 11 
 
 3 
 
 4 4 Ai 
 
 2 
 
 sV^ 
 
 1 
 
 67, 
 
 1 
 
 
 «7u 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 to 1 year 
 
 4 
 
 I 
 
 4 
 
 8 
 
 » T Ai 
 
 11 
 
 2 10 / 
 
 11 
 
 1 
 
 47n 
 
 6 
 
 8 
 
 
 7xx 
 
 
 
 
 
 
 
 
 Normal 
 
 «/ 
 
 / 11 
 
 1 
 
 i7» 
 
 1 
 
 Vu 
 
 
 7, 
 
 1 
 
 2 
 
 iVxi 
 
 2 
 
 I7n 
 
 
 l7xx 
 
 
 
 
 
 
 
 
 to 1 year 
 
 
 
 i7n 
 
 4 
 
 * T /ii 
 
 5 
 
 i7, 
 
 1 
 
 2 
 
 »7tx 
 
 4 
 
 27.x 
 
 2 
 
 67 xi 
 
 5 
 
 8 / 
 
 / 11 
 
 
 
 
 
 
 1 to 2 years 
 
 
 
 
 
 Vu 
 
 
 7, 
 
 1 
 
 i 
 
 *7u 
 
 1 
 
 l7xx 
 
 2 
 
 l7xx 
 
 5 
 
 4 
 
 2 
 
 l7xx 
 
 
 
 
 2 to 3 years 
 
 
 
 
 
 
 
 
 
 
 
 
 7xx 
 
 
 7xx 
 
 1 
 
 2 2 / 
 
 2 
 
 8 7 /ii 5 
 
 
 
 
 3 to 4 years 
 
 
 
 
 
 
 
 
 
 
 
 
 7xx 
 
 
 
 
 7xx 
 
 1 
 
 7xx 5 
 
 8 / 
 
 /11 
 
 3 
 
 
 4 to 5 years 
 
 
 
 
 
 
 
 
 
 
 7xx 
 
 
 
 
 
 
 7xx 
 
 
 7xx 
 
 V 
 /11 
 
 3 
 
 8 / 
 
 /11 
 
 5 to 6 years 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 1 
 
 TABLE III 
 
 
 6 
 
 W N 
 
 7 
 
 W N 
 
 5z; 
 
 00 
 
 £ 
 
 1 
 
 w‘ 
 
 X 
 
 10 
 
 W N 
 
 11 
 
 W N 
 
 12 
 
 W N 
 
 13 
 
 W N 
 
 14 
 
 W X 
 
 15 
 
 W X 
 
 16 
 
 W X 
 
 Advanced 
 
 47xi 4 
 
 lO^/xx 11 
 
 97:x 12 
 
 11 V 
 
 u 1 
 
 6>7xx 7 
 
 8 
 
 7xi 
 
 
 
 
 
 Normal 
 
 7ix i 
 
 l7 11 1 
 
 7xx 
 
 7 
 
 LX 2 
 
 i7u 2 
 
 I7xi 
 
 l7xx 
 
 
 
 
 
 Retarded 
 
 
 l7xx 4 
 
 4 5 
 
 27 
 
 x 3 
 
 57xx 5 
 
 47 xx 4 
 
 8 11 
 
 7 7 /xx 5 
 
 57xx 10 
 
 I7xx 7 
 
 8/ 1 
 / 11 1 
 
 TABLE IV 
 
 
 6 
 
 W N 
 
 7 8 
 
 W N : W X 
 
 9 
 
 W 
 
 10 
 
 N W N 
 
 11 
 
 W X 
 
 12 
 
 W X 
 
 13 
 
 W X 
 
 14 
 
 W X 
 
 15 
 
 W X 
 
 16 
 
 W X 
 
 Advancement 
 
 Units 
 
 Retardation 
 
 Units 
 
 13 7(19) 
 
 58 15(41) 45 13(3(5) 
 
 4 4(11) 12 5(14) 
 
 60 1 
 
 9 4 
 
 (3) 25 8(22) 
 
 (11) 26 6(16) 
 
 22 
 
 22 6(16) 
 
 1 
 
 29 18(49) 
 
 51 14(38) 
 
 45 35(96) 
 
 13 33(91) 
 
 10 6(16) 
 
APPLICATION OF THE BINET-SIMON TESTS 
 
 55 
 
 shows advancements and retardations in terms of 1/5 years, after 
 the familiar Binet-Simon method. 
 
 Table No. 2 is inserted for purposes of convenience to pro¬ 
 vide a summary of Table 1. The figures are the same as in the 
 first table except that they are for years, instead of for fifths of 
 years. 
 
 Table No. 3 is a summary of the total percentages retarded, 
 advanced and normal for both races. Inasmuch as only those 
 were counted normal who were exactly at the age level to the 
 fifth of a year, the number seems small. The reckoning of the 
 actual age of the children in fifths of a year was done easily and 
 accurately by consulting the school records of the date of birth. 
 
 A view of the final results is given in Table No. 4, which is 
 so arranged that at a glance one may observe the relative results 
 from the two races, without being confused by the fact that there 
 were about two and a half times as many whites as negroes con¬ 
 cerned in the tests. Also the total amount of retardation is in¬ 
 dicated, as well as the number retarded. These are two different 
 things, for while one race might have more actual cases of re¬ 
 tardation than the other, in the case of the second race the de¬ 
 gree of retardation in the cases of those who were backward 
 might be comparatively very high. Therefore the Table is an 
 arrangement of what may be called “retardation units.” A “re¬ 
 tardation unit” may be considered as one case retarded for one 
 year or for part of one year. Thus the retardation of a child three 
 years behind his age level would be recorded as three units. “Ad¬ 
 vancement units” are reckoned in a similar way. The figures 
 which give the units of retardation and advancement for the 
 negroes are followed by other figures in brackets. These brack¬ 
 eted figures are the numbers of units earned by the negroes mul¬ 
 tiplied by 11/4. The figures thus obtained are directly com¬ 
 parable with the number of units earned by the whites, and en¬ 
 ables the reader easily to compare the performances of the two 
 races. 
 
 If these results are carefully examined it will be seen that the 
 whites make, in the whole, a little the better showing. The great- 
 
56 
 
 GEORGE R. WELLS 
 
 est advancement reckoned in terms of averages is white, and the 
 individuals which were most advanced were white. On the other 
 hand the greatest retardation in point of averages, and the most 
 retarded individuals were negroes. The arrangement in terms 
 of retardation units is still more strongly indicative of an ad¬ 
 vantage on the part of the whites. The total number of retarda¬ 
 tion units on the part of the whites is 221, and on the part of the 
 negroes is 358. The advancement units for the whites number 
 224, and for the blacks 121. In both of these cases the figures 
 given for the negroes is that obtained by the equalization pro¬ 
 cess of multiplying the actual number of negro units by 11/4. 
 Judging by any of these Tables there is a small but not insignifi¬ 
 cant advantage in favor of the whites. 
 
 But far more important than the mere fact of a better showing 
 made by one of the racial groups is the arrangement of the re¬ 
 sults as regards ages. It is very noticeable that the negroes are at 
 least equal to the whites at the ages of six, seven, and eight. Nor 
 are the negroes very markedly inferior to the whites at the ages 
 of nine, ten and eleven. At twelve years there is a marked dif¬ 
 ference, and it becomes progressively more marked from twelve 
 to sixteen, reaching its climax at fourteen and fifteen. Evidently 
 the children start in on equal terms, and maintain that equality 
 for some years. But gradually the negroes lag behind, and at 
 about the age of finishing grammar school or entering high school 
 seem to be definitely inferior to the whites. There are, of course, 
 many exceptions. These results are to be understood as averages 
 of performances of a moderately large number of school children. 
 Their significance must not be mistaken nor exaggerated. But 
 it seems to be beyond doubt that under the conditions mentioned, 
 and using the tests which we used there is no difference in the 
 reactions of white and colored children up to the age of ten or 
 eleven. At the age of twelve a difference is noticeable, which 
 difference becomes very prominent at fourteen, fifteen and sixteen 
 years of age. That the negroes are outstripped seems undeniable. 
 
 It remains to determine the cause of this difference. The 
 simplest explanation and that which comes first to one is that 
 
APPLICATION OF THE BINET-SIMON TESTS 
 
 57 
 
 it is a manifestation of some inherent mental superiority of the 
 white race over the negro. But it seems evident to the writer 
 that such an explanation can not be applied in this specific case. 
 One reason will sufficiently dispose of it, and that is the impossi¬ 
 bility of determining the purity of blood of many negroes. Be¬ 
 yond all doubt most, if not all, of the colored children examined 
 have some mixture of white blood, in proportions impossible to 
 determine. 
 
 The correct explanation will probably be found when the 
 social conditions and limitations of the two races are examined. 
 Mr. Howard L. Rawdon, the Superintendent of the Oberlin 
 School System, has gone into the question of the social differences 
 confronting the two races in a report presented to the Department 
 of Education of Oberlin College and entitled “The Colored 
 Pupil in the Oberlin Public Schools.” He points out that the 
 limitation of possible professions for negroes is so great that 
 there is smaller incentive to continue at school than operates in 
 the case of the white children. He also shows that the economic 
 position of the negroes in Oberlin is not good. The colored peo¬ 
 ple constituted something more than 18% of the population of 
 Oberlin in 1913, but owned no more than 4% of the taxable 
 property. And what is still more significant is the fact that less 
 than 7/10 of one percent of the personal property is owned by 
 negroes. The percapita wealth of the whites is more than five 
 times that of the colored people. Further, records of crime in 
 Oberlin show that the colored people are responsible for far more 
 than their share, calculated on their proportion of population. 
 And this criminal tendency becomes even more marked if serious 
 crimes only be considered, and mere violations of local ordinances 
 be neglected. 
 
 The social and moral conditions so briefly mentioned above 
 may properly be held responsible for the very great irregularity 
 of school attendance and for the large amount of tardiness in 
 the case of negro children in general. Mr. Rawdon states that 
 the school records show that the colored pupils are absent prac¬ 
 tically fifty percent more than the white pupils, and that the boys 
 
58 
 
 GEORGE R. WELLS 
 
 are absent oftener than the girls, the reverse of the case with the 
 whites. It is also very significant that the colored pupils drop 
 out of school much earlier than do the whites. For instance, in 
 the four lower grades 27.4 % of the enrollment is colored; in the 
 four upper grades, 21.8% and in the High School but 10.3 % 
 are colored. No doubt much of this absence and early leaving of 
 school is due to economic pressure driving the children to work, 
 much of it is also due to the generally unpromising outlook for 
 the colored student, even if he does graduate from High School. 
 And to this latter cause and the unambitious attitude it en¬ 
 genders is due the excessive amount of tardiness, which Mr. 
 Rawdon also notes. 
 
 The writer feels that the probability is that the disparity in 
 performance between the groups of white and colored children 
 which he and his assistants tested is due to social and environ¬ 
 mental factors rather than to inherited or racial traits of mental 
 ability. 
 

 
 
 
 
 
 
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