Open Access

JSON Export

{"created":"2022-01-31T12:57:49.197899+00:00","id":"lit28746","links":{},"metadata":{"alternative":"Studies from the Yale Psychological Laboratory","contributors":[{"name":"Davis, Walter W.","role":"author"}],"detailsRefDisplay":"Studies from the Yale Psychological Laboratory 6: 6-50","fulltext":[{"file":"p0006.txt","language":"en","ocr_en":"RESEARCHES IN CROSS-EDUCATION,\nBY\nWalter W. Davis.\n' I. Historical.\nThe term \u201ccross-education\u201d has been used1 to express the fact that the effects of practice on one side of the body are transferred to the unpracticed side. The fact seems to have been first recorded by H. F. Weber. In a communication to Fechner,2 he reports an observation made on his son. The boy had been taught to write entirely in one system of penmanship, a system that employs a free-arm muscular movement. At the age of thirteen he was able to write reversely with the left hand \u2014in so-called mirror-writing\u2014without having practiced such writing in the least, although the letters were not so regularly made as those made with the right hand. The reverse writing, when viewed in a mirror, or when looked at through the paper as it was held to the light, appeared very similar to the boy\u2019s ordinary hand-writing. Hence Weber concluded that by the training of the right hand in certain methods of penmanship the left hand is also trained, unconsciously, to perform symmetrical movements. He noticed also that others trained by different methods, or by several methods, failed in the test.\nFechner reached a similar conclusion from an experience of his own. In the course of a series of observations in which he wrote the figure p many times, left-handed, he noticed that when he took the pen in his right hand, he would unconsciously write the figure reversed with a movement that was symmetrical to that made with the left hand. A certain method of writing had become so \u201cimpressed upon his mind\u201d that it became natural to write reversely with the hand not used.\n1\tScripture, Smith and Brown, On the education of muscular control and power, Stud. Yale Psych. Lab., 1894 II 115.\n2\tFechner, Beobachtungen, welche zu beweisen scheinen, dass durch die Uebung der Glieder der einen Seite die der andern zugleich mitge\u00fcbt werden, Ber. d. kgl.-s\u00e4ch. Ges. d. Wiss., math.-phys. CI., 1758 X 70.\n6","page":6},{"file":"p0007.txt","language":"en","ocr_en":"Researches in cross-education.\n7\nThe experiments of Volkmann,1 * on the influence of practice upon the power for perceiving small distances, have a bearing on cross-education. By touching a Weber\u2019s compass to the skin on various parts of the body, he obtained records of the ability of the several members to distinguish the two points of the compass at the smallest perceptible spread. For example, the left arm on the dorsal side could distinguish the two points at 10.5 Parisian lines (23.6\"\u201d\"); the right arm at 11.5 lines (26.41,,m). At the end of the practice which was continued for several weeks with the left arm alone, the records were : left, 5 lines (ii.2mm), right, 7 lines (15.7\u201d\u201c\u201c). While the acuteness of sense on the left side was increased through local practice, it was also increased on the right side in portions symmetrical with the parts practiced.\nTo determine whether other than symmetrical parts are thus trained, Volkmann tested the points of the fingers of both hands and also the left arm. By practice of one of the fingers of the left hand, he found an increase in ability in all the fingers, but none in the arm. That is, in the education of certain parts, those parts symmetrical and closely related are educated also.\nMore recently Scripture 2 has made some experiments in muscular control and muscular power which prove quite definitely that practice of one arm in steadiness and strength reacts on the other arm as well. Dr. W. G. Anderson, Associate Director of the Yale Gymnasium, experimenting with the spring dynamometer, has reached practically the same conclusion. Bryan,3 in testing the tapping ability of children of different ages, concludes that the right hand does not outgrow the left, but that, at certain ages, the left even gains on the right.\nThe following experiments were carried on, during the academical year of 1898-99, for the purpose of establishing more definitely the fact of cross-education or transference of practice and, if possible, of finding the causes of such transference.\nII. Rapidity of voluntary effort.\nThe present investigation was begun by experiments in the rapidity of tapping on a telegraph key. The movement in tapping involved only a small amount of muscular strength. The weight of the finger was sufficient\n1 Volkmann, Ueber den Einfluss der Utbung auf das Erkennen r\u00e4umlicher Distanzen, Ber. d. kgl.-s\u00e4chs. Ges. d. Wiss., math.-phys. Ci., 1858 X 38.\n* Scripture, Smith and Brown, On the education of muscular control and power, Stud. Yale Psych. Lab., 1884 II 114.\n3 Bryan, On the development of voluntary motor ability, Amer. Jour. Psych., 1892-93 V 201.","page":7},{"file":"p0008.txt","language":"en","ocr_en":"8\nWalter W. Davis,\nto press down the button of the telegraph key, so that the test was one of motor ability with the factor of muscular power seemingly almost eliminated.\nApparatus.\nThe tapping was done by the subject in a quiet room, while the results were recorded in an adjoining room. The number of taps in a given\ntime was recorded on a tap counter which was connected by electric wires with the key. It consisted of clock-work with hour and minute","page":8},{"file":"p0009.txt","language":"en","ocr_en":"Researches in cross-education.\n9\nhands. At the back (Fig. i) there is a toothed wheel worked by an electro-magnet ( G) and an armature (AT). When a current passes through the magnet, the armature is attracted ; when it ceases, the armature is drawn back again by a wire spring. The upper end of the lever (R), of which the armature is a part, divides into two arms (R>), each of which, one on each side, may press successively into a toothed wheel (A) in such a way that at each make and break of the electric current the wheel is driven forward one cog. This movement arises from the shape of the ends of the arms and of the teeth of the escapement wheel. A friction spring ( C ) hinders any backward movement. This counter has been in use in the laboratory for several years. Its special merit lies in the fact that it will count the most rapid taps that a person can possibly make. The number of taps is recorded on the face of the counter. A key within easy reach makes it possible, while the subject is tapping in the quiet room, for the observer to let the current pass or not, as he chooses.\nIn the quiet room, three keys were so arranged that the subject could, without changing his general position, tap with either hand or either foot. One key served for the hands and was clamped to a board which was held in the lap. With the subject seated in readiness for tapping, the board was supported by the arms of the chair and the elbows rested easily on the board, the hand just reaching the key. The tapping was done with the index finger, the subject being instructed to keep the other fingers, the wrist and the forearm on the board. This position allowed a rapid, easy, isolated movement without the use of cl\u00e0mps or weights that might distract the attention.\nFor the feet a board was so constructed that two keys, four inches apart, could be set into the top, their ends touching at one edge and leaving the buttons only a little more than flush with the surface of the board. The tapping was restricted to the great toe, all movement being confined as much as possible to this member. The chair remained always in the same position and the board could be moved on the floor, forward or backward, to suit the convenience of each subject. When a certain position was adopted for any subject, the conditions remained constant for him through the entire series of experiments.\nFor the purpose of communication the two rooms were connected by a system of signals, by which the observer could direct the subject to start or stop. In all cases the number of taps in five seconds was recorded. With all in readiness, the observer, with watch at hand, signaled the subject to start. At three seconds after the start the switch was closed and the counter began to record. After five seconds the switch key was opened and the subject signaled to stop.","page":9},{"file":"p0010.txt","language":"en","ocr_en":"IO\nWalter W. Davis.\nMethod of experiment.\nIn this series of experiments, the results of which are shown in Table I., tests of tapping-ability were made on six subjects. Of these, A. is-an instructor, and B., C., D. and F. are students in Yale University. E. is the steward of the Psychological Laboratory. Initial tests were taken of the right and left index fingers, and of the right and left great toes. Then for periods varying from ten to twenty days the right great toe was practiced daily, or nearly so. At the end of the practice period final records were taken of each member. The initial and final tests were taken in the following order : for subject A. LF RF LH RH RH LH R F LF; for B. LF RF LH RH LF RF LH RH; forC., D., E. and F., LF RF RH LH LH RH RF LF (RH\u2014right hand, LH\u2014 left hand, RF\u2014right foot, LF\u2014left foot). In this way the liability to differences due to fatigue was guarded against. In each initial and each final test, averages were taken of the two records made by each member. A specimen record is inserted, the first one taken.\nSubject A.\u2014Initial test.\n\tLF\tRF\tLH\tRH\tRH\tLH\tRF\tLF.\n\t13\t17\t24\t26\t28\t24\t19 '\t11\nAverage.\t12\t18\t24\t27\t\t\t\t\nThe initial and final tests were taken at the same time of the day, and, as nearly as possible, under similar conditions. Lombard1 2 and Dresslar have pointed out the differences in voluntary strength and rapidity due to varying conditions. An effort was made to equalize them for all records.\nResults.\nThe results obtained are shown in Table L, which gives the numbers of taps in five seconds for each member at both initial and final tests, also the gain in the number of taps, and the gain as a percentage of the initial number.\nThe effects of practice are not uniform. Not only is there a great difference between the gains made by different individuals, but also between the gains of different members of the same individual. Still, certain fundamental results are clearly shown. In the first four subjects, whose initial and final records are given ini able I., a marked increase in the rapidity of tapping ability has been developed ; and this increase mani-\n1\tLombard, Some of the influences which affect the power of voluntary muscular con-traction, Jour. Physiol., 1892 XIII 2.\n2\tDresslar, Influences affecting the rate of voluntary movement, Amer. Jour. Ps-ych., 1892 IV 514.","page":10},{"file":"p0011.txt","language":"en","ocr_en":"Researches in cross-education.\nil\nfests itself not only in the right foot, which alone was practiced, but in all the other members as well. However, the greatest average gain is-\nTable I.\nNumber of taps in 5 seconds.\nSubject.\t\tInitial test.\tFinal test.\tGain.\tRelative gain.\n\tf LF\t12\t17\t5\t0 41\nA.\t! RF\t\t18\t20\t2\tO.II\n\\ LH\t\t24\t28\t4\t0.17\n\tL RH\t27\t32\t5\t0.18\n\tr lf\t15\t17\t2\t0.13\nB.\tRF\t14\t21\t7\t0.50\n\tLH\t22\t36\tH\t0.64\n\tRH\t22\t34\t12\t0.54\n\tf lf\t20\t26\t6\t0.30\nC.\tRF\t21\t28\t7\t\u00b0-33\n\tLH\t32\t36\t4\t0.13\n\tRH\t37\t42\t5\t0.14\n\tr lf\t17\t25\t8\t0.47\nD.\tRF\t20\t28\t8\t0.40'\n\tJ.H\t26\t34\t8\tc-31\n\tL RH\t27\t29\t2\t0.07\n\tLF\t16\t22\t6\t0.38\nE.\tRF\t21\t20\t\u2014i\t\u20140.04\n\tLI1\t22\t24\t2\t0.09\n\tRH\t\u00b14\t22\t\u20142\t\u2022\u20140.0S\nf lf\t\t16\t17\ti\t0.06\nF-\tRF\t21\t*9\t\u20142\t\u20140.09\n\tLH\t30\t24\t\u20146\t\u20140.20\n1 RH\t\t33\t28\t\u20145\t\u20140.15\n\tLF\t16\t21\tS\t0.31\nAverage.\tRF\t19\t23\t4\t0.21\n\tLH\t26\t3\u00b0\t4\tOI5\n\tRH\t28\t31\t3\t0.08\nAverage:\tLF\t16\t21\t5\t0.31\nA, B,\t!\tRF\t18\t24\t6\t0-33\nC, D.\t'\tLH\t26\t34\t8\t0 31\n\tRH\t28\t34\t6\t0.21\nmade by the member practiced. The gain by RFis slightly greater than that of LF and LH, and considerably greater than that of RH.\nIn neither E. nor F. is there a gain in the member practiced, but rather a slight loss. In only one member not practiced, LF of subject E., is there a marked gain, while in RF, LH, and RH of subject F., are there marked losses.\nIn the second average the records of subjects E. and F. were not used, the object being to give the comparative average results of practiced and unpracticed members in subjects who made a gain in the member practiced.","page":11},{"file":"p0012.txt","language":"en","ocr_en":"12\nWalter IV. Davis,\nFrom certain observations taken during experimentation, as well as from remarks and suggestions made by the subjects themselves, these facts appear to be satisfactorily explained. Subject E. is a colored man, the steward of the laboratory, thirty-four years of age, of a phlegmatic temperament, steady-going rather than quick and active. The two facts of age and temperament are suggested as the reason for his not responding more quickly to practice. In the gymnasium it is illustrated every \u25a0day that after a certain age the boy loses in a great degree the ability to learn new tricks. Moreover boys differ individually in the ability to learn. This difference is not due wholly to lack of strength but to temperament, will-power and previous training as well. Possibly, with longer practice, good results might have been secured from E. Subject A. was of the same age as E\u201e but the practice in his case was continued twenty days and in the case of E. only ten days ; the two subjects differ much in temperament, A. being nervous rather than sluggish.\nTable II.\nInfluence of age ; number of taps in J seconds.\n\t\tAverage gain\tRelative\tDays of\tRelative\nSubjects.\tAge.\tof the four members.\tgain.\tpractice.\tgain per day.\nA. B. C. D.\t34 29 25 27\t4 9 6 6\t0.20 0.44 0.22 0.27\t20 H 10 10\tO.OI 0.031 0.022 0.027\nAge seems to play an important part in the results obtained from practice. Table II. gives the ages of the subjects in connection with the average gain they make for both hands and both feet, the length of practice, and the gain per cent, for each day of practice. To obtain a fair increase in the rapidity of tapping, the practice of A., who is 34 years old, had to be continued for 20 days, and then the gam is less than that of B., C. and D., where the practice was continued for 14, 10.and 10 days respectively, and the ages were 29, 25 and 27 years.\nAn interesting principle was exemplified in the failure of F. to make a gain in rapidity by practice. F. is an academical senior, aged 23, the youngest of the six subjects, and of a nervous motor temperament. He is a trained gymnast of more than moderate skill. One would judge that conditions here were favorable for a rapid gain in tapping ability. Some of his remarks, however, after the daily practice, throw light on the difficulty. \u201c If I try to hurry too much my foot stops almost altogether. \u201d \u201cAt times I am obliged to put forth my entire will power in order to tap at all.\u201d \u201cI feel fatigued all over \u201d ; that is, fatigue did not confine itself","page":12},{"file":"p0013.txt","language":"en","ocr_en":"Researches in cross-education.\t13\nto the muscles involved but was general. It would seem that, in this-subject, temperament and training had combined to form conditions-unfavorable to rapidity of tapping. Naturally of a quick, nervous, active disposition, his training as a gymnast had emphasized these qualities. The proper execution of difficult gymnastic tricks requires a great exertion of strength and also its quick concentration at a particular moment in time. The subject had become so accustomed to sending down strong impulses to action to large muscles, that it was difficult for him to send proper impulses for the action of small muscles like those of the fingers and toes. Subject F.\u2019s great store of energy is illustrated in his long practice records. It seemed impossible to tire him out. In. one experiment he made 900 taps without a slowing in rapidity of taptime. He concentrated more attention at one point than was favorable for rapidity of movement. So great an amount of nervous energy was sent to this point that the delicate muscles could not properly dispose of it for action, and the result was a slowing of movement.\nOn the whole, the subjects were a group not favorable for rapid improvement from practice. Of an average age of 28 years, they had gotten beyond the point in physical development where either muscular or nervous changes would take place rapidly. With younger subjects larger and more rapid gains might reasonably be expected. Nevertheless, the principle of cross-education appears most plainly and decisively.\nSince obtaining the above results, I have received a letter from Herr Oscar Raif, Professor of Music in the Berlin Hochschule, who has done some experimenting similar to mine. I quote a portion of his letter, inserting the number of beats per minute in [\t] .\n\u201cIn the spring of. \u201998, I made an experiment with twenty of my pupils. I began by taking the average speed of each hand with the metronome. The average of the right hand was I = n6 (= four times 116 in the minute) [464 beats] and for the left hand, 112 [448 beats]. I gave them exercises for the right-hand only (finger exercises, scales and broken accords) to develop rapidity. After one week the average of the right hand was 120 [480], after two weeks, 126 [504], three weeks, 132 [528], etc. After two months the right hand yielded 176 [704]. Then-I had them try the left hand which averaged 152 [608], whereas in November the average was only 112 [448]. In two months\u2019 time, absolutely without practice, tha left hand had risen from 112 [448] to 152-[608]. A few of my pupils had some difficulty in playing the scales in parallel motion', but were able to play them in contrary motion.\n\u201c The tenor of my work is that in piano playing the chief requirement is not that each single finger should move rapidly but that each movement","page":13},{"file":"p0014.txt","language":"en","ocr_en":"14\nWalter W. Davis,\nshould come at exactly the right time, and we do not work only to get limber fingers but more than that to get perfect control over each finger. The source of what in German is called \u2018 Fingerfertigkeit \u2019 is the center \u25a0of our nervous system, the brain.\u201d\nFurther explanation of the application of these principles in musical training is promised in a work on \u201cFingerfertigkeit\u201d by Professor Raif. The fact that Herr Raif\u2019s pupils could play the scales in contrary more \u2022easily than in parallel motion, deserves notice as coinciding with the observations made by Weber and Fechner in regard to mirror-writing.\nTable III. gives the relative rapidities of hands and feet, both before and after practice, and their average percentage of gain. The ratio of tapping ability is smaller at the end of the practice than at the beginning ; \u2022the relative gain of the feet being 5.5% greater than that of the hands.\nTable III.\nComparative rapidity of hands and feet.\n\t\tInitial.\tFinal.\tRelative gain.\n1\tf Feet.\tIS\t18\t0.24\nA.\t\\\tHands.\t25\t30\t0.16\n!\t[ Ratio.\t1:1.7\t1:1.6\t\n1\tf Feet.\tH\t18\t0.31\nB.\tHands.\t22\t35\t0.58\n1\t[ Ratio.\t1:1-5\t1:1.8\t\n%\tI\tf Feet.\t20\t27\t'O.32\nc.\t\u2022!\tHands.\t34\t38\t0.12\n1\t[ Ratio.\t1:1.6\t1:1.4\t\n1\tf Feet.\t19\t26\to-39\nD.\t-\tHands.\t27\t31\t0.17\n1\t[ Ratio.\t1:1.4\t1:1.2\t\n1\tf Feet.\til'/s\t22)4\t0.31\nTotal Average\tj\tHands.\t27/s\t23'A\t0.26\n\t[ Ratio.\t1:1.6\t1:1.5\t\nIn the case of D. two facts are noticeable from an examination of the table : ( 1 ) lower ratios between feet and hands both before and after practice; and (2) a greater percentage of gain in the tapping ability of the feet in comparison with the other subjects. During D. \u2019s practice it was observed that he had an almost independent use of his great toe. He \u25a0could flex or extend it, with very little accompanying movement of the remaining toes. D. is a Japanese student and while in Japan wears the ordinary clog shoe which allows free movement of the great toe. A heavy string extending up for an inch from the middle forward part of -the sole divides into two parts which pass back, one on either side of the foot. When the shoe is adjusted to the foot, the string before its division","page":14},{"file":"p0015.txt","language":"en","ocr_en":"Researches in cross-education.\n15\nis grasped between the first and second toes, and the shoe is held in place by this means. The sock also is made in the form of a mitten, the great toe being in a separate compartment from the others. The sock is the only covering of the foot above and to the sides. Hence two prime conditions for development are here present, exercise and room for growth. These facts probably account for the smaller ratio between the rapidity of toes and fingers in the case of D. They also emphasize the fact already pointed out1 * that the feet of Americans are losing, as a result of tight, ill-formed shoes, those powers natural to them. The reason why the feet in the case of D. should make a greater percentage of gain than in the other subjects, although not so clear, is probably due to the same cause.\nInfluences affecting the rapidity of tapping.\nIn the daily practice the right great toe tapped until fatigued. There was, however, no attempt to reduce the muscles to a state of extreme fatigue, since the increase in tapping ability at the final test was the prime object. The records were made in a manner similar to those at the initial and final tests. The signal to start was given ; after three seconds the switch was closed and a record was obtained for five seconds. The result was noted while the subject continued to tap without stopping, and after ten seconds another record was taken. The subject and the observer continued in this manner, the record being taken at every third period of five seconds, until the subject stopped tapping.\nA study of these records and of the remarks dropped by the subjects led to several important observations.\n(a) There are perceptible variations in the rapidity of the tap-time on any given occasion of practice. One subject says : \u201cAt times it is very \u2022easy to tap rapidly ; then it becomes difficult ; then easy again.\u201d Another subject noticed what he termed \u201cwaves,\u201d that is, short periods of \u2022rapidity followed by a slowing of the tap-time. These waves of rhythm have been noticed by Noyes 2 in the knee-jerk ; and- also by Lombard 3 in his work with the ergograph. They seem to be wholly beyond the \u25a0control of the will.\nThis phenomenon is shown in Fig. 2 which gives the curve for a Tecord by A., the twelfth in his series of practice records. X indicates the serial number of the record, and Y the number of taps in five sec-\n1 Ellis, The hutnan foot, Wood\u2019s Medical and Surgical Monographs, April 1890.\n\u2022Noyes, On certain peculiarities of the knee-jerk in sleep, Amer. Jour. Psych., 1892\n3V 343.\n3 Lombard, Alterations in the strength -which occur during fatiguing voluntary muscular work, Jour. Physiol., 1893 XIV 98.","page":15},{"file":"p0016.txt","language":"en","ocr_en":"16\tWalter W. Davis,\nonds. The continual fluctuation between gain and loss in energy is quite striking.\n/6 n /b\n/Z 13 /f IS\nn /3 /4 fi- is\nn /B\nFig. 2.\nX, upper line, serial number of record.\nX, lower line, successive steps in the subject\u2019s practice. Y, number of taps in 5 seconds.\n(h) States of feeling do not appear to have much effect on the rapidity of tapping. Often the subject would remark that he did not feel like making a good record and when the record was taken it would prove excellent. The reverse is true also. One of the subjects remarked before a certain practice that he had partaken of a fine punch the night before, had had a good night\u2019s rest, felt in excellent spirits and expected to make an unusual record. After the experiment the result was compared with the previous ones and the taps were found to be slower than any in the preceding three days. There were many other similar, though less notable, instances of the deceptiveness of the subject\u2019s judgment of his own condition.\n(r) On the other hand, the physical condition of the hand or foot as judged by sensations had a noticeable effect on the tapping ability. On one very cold morning the subjects, without exception, made poor records ;; most of them had complained of cold feet, due to the exposure of the bare foot in the cool air.\nTable IV.\nEffect of exercise.\nDay,............................   I\t234567\t89\nRecord during\tfirst 5 seconds, .. 16\t15 14 19 17 20 23\t17\t23\nRecord during\tsecond 5 seconds, . 24\t20 18 24 24 28 28\t22\t22\n(d) Tapping could be done faster and more easily after a few taps had been made, or as C. expressed it, after the muscles had been \u201cwarmed","page":16},{"file":"p0017.txt","language":"en","ocr_en":"Researches in cross-education.\n17\nup.\u201d Table IV. gives the first two records of each of the practice experiments for D.\nThe results show that either the muscular or the nervous system or both do not do their best work at the start.\n(<?) Pain and fatigue, when they were noticed at all as the result of continued tapping, were generally located in or near the muscles employed in the movement. Rarely indeed was fatigue spoken of as being general.\n(/) The length of time during which the subject kept up his practice was a good indication of his store of energy. There was a tendency to longer practice-records on Mondays and on any day preceded by a day of rest from tapping. Apparently the muscular or nervous energy expended in the performance of one day\u2019s task was not fully restored in one day, the tissues requiring .a day\u2019s rest to regain their normal capacity for work.\n(g') Tapping became much easier after a few days of practice ; the apparent reason was that it did not require so much attention. This points to the probability that lower, automatic centers were being developed for the foot in the specific movement of tapping, leaving less responsibility for the act upon the higher centers of consciousness and attention.\n(\u2019h) Subject A. experienced sensations of pain in his unused left great toe similar to those in the right which was being fatigued by the tapping. He has noticed the same fact in connection with \u201cwriter\u2019s cramp\u201d which has troubled him at various times ; the numb sensation of the right middle finger is sometimes transferred to the left middle finger for periods varying from a few minutes to hours. He does not use the left hand for writing.\nThe loss of the effects of practice.\nTo determine if the effects of practice are retained for a long period of time, A.\u2019s record was obtained six weeks after his final test. Table V. shows the results compared with his initial and final tests.\nTable V.\nEffect of a long interval.\nSubject.\t\tInitial.\tFinal.\tAfter six weeks.\n\tLF\t12\t17\t18\nA\tRF\t18\t19\t16\nA\t*\tLH\t24\t28\t24\n\tKH\t27\t32\t30\nAverage\t\t20\t24\t22\n2","page":17},{"file":"p0018.txt","language":"en","ocr_en":"i8\nWalter W. Davis,\nThere was a general loss after the interval. This loss was more marked in the hands than in the feet ; the average loss for the hands was 3 ; for the feet, 1.\nIII. Strength of voluntary effort.\nIt has already been proved that the development in the strength of one arm is accompanied by an increase in the exertion that can be put forth by the other.1 Is this increased power due to increased nervous activity or to increased muscular tissue ?\nThe following experiments were undertaken primarily to determine if an increase in the size of one arm would result from the exercise of the other in muscular strength and endurance. From previous experiments, referred to in Sec. I., an increase of strength was looked for in both arms. It was not believed that a perceptible increase in the girth of the left arm would result after so short a period of training.\nMethod of experimenting.\nThe experiments were made in the following way : six subjects were chosen, definite girth measurements of both arms were taken, and the number of times ascertained that each arm could raise a weight of 2 % kilos, (s pounds).\nAt the initial test the subject\u2019s clothing was removed from the upper part of his body. His weight was then taken and his strength of forearm, or grip, measured by the usual oval spring dynamometer. The following measurements were then made by Dr. J. W. Seaver, Associate Director of the Yale Gymnasium : right and left upper arm both flexed and extended ; right and left forearm with and without the hand clenched. These measurements were taken at the largest circumferences of the arm above and below the elbow. The weight (a 2 kilo, dumbbell) was then given to the subject, who was instructed to lift it from a position where the arm hangs extended downward and the weight is supported from the shoulder, to one where the arm is flexed and the weight close to the shoulder. In this movement the elbow remains stationary. Hence, to accomplish this act, the biceps is employed almost wholly, though the muscles of the forearm are also used to a lesser extent in gripping the dumbbell. This gripping was intensified toward the end of the test, when the subject became fatigued.\nA metronome was not used, but each subject was allowed to fall into his own rhythm of movement, which varied according to the length of the arm\n1 Scripture, Smith and Brown, On the education of muscular control and pozver, Stud. Yale Psych. Lab., 1894 II 114.","page":18},{"file":"p0019.txt","language":"en","ocr_en":"Researches in cross-education.\n19\nand the man\u2019s temperament. The only instruction he received was not to allow the weight to stop at its highest and lowest points. At the final test it was observed that the rate of motion was unconsciously faster than at the initial test. This was probably due to an increase of energy stored up during the practice.\nFatigue was not carried to an extreme, because such a test would put the arm and the physical system in general into such a condition that good results could not be expected from the succeeding short practice. When the right arm was fatigued, a rest of five minutes was given, after which the left arm went through the same exercise.\nThe subject then entered upon a practice extending from two to four \u2022weeks ; this consisted in simple flexions of the right arm with the weight. The subjects were instructed not to tire the arm but to exercise it fre quently and lightly, rather than heavily and at long intervals.\nAt the final test the same data were obtained in the same way and under the same conditions as at the initial test. Additional data were also obtained, to be spoken of later. The arms were examined by pressure to detect any changes in condition that might have been occasioned by practice.\nCharacteristics of the subjects.\nAs the results indicated that the age, physical condition and mode of life of each subject should be taken into consideration, the following data were collected :\nG.\tAge, 28. Health, fair. Temperament, nervous. Muscles, soft, undeveloped. Exercise, light gymnasium.\nH.\tAge, 26. Health, good. Temperament, phlegmatic. Muscles, soft. Exercise, light.\nB. Age, 29. Health, good. Temperament, nervous. Muscles, soft. Exercise, none. Left-handed in most actions.\nI.\tAge 26. Health, good. Temperament, nervous. Muscles, \"firm, well developed Exercise, regular, in gymnasium.\nJ.\tAge, 26. Health, excellent. Temperament, motor. Muscles, well developed, but soft. Exercise, none.\nK.\tAge, 24. Health, not good, over-worked. Temperament, \"nervous. Muscles, soft and very poorly developed.\nThe subjects were all in a muscular condition favorable to increase in girth measurements, but their average age of 26 years was probably unfavorable for such an increase. They were all members of the Graduate School of Yale University. Those who were taking any physical exercise, were instructed to continue it throughout the practice.","page":19},{"file":"p0020.txt","language":"en","ocr_en":"20\nWalter IV. Davis,\nIncrease in the dimensions of the arms.\nTable VI. shows the girth measurements taken at the initial and final tests and the increase due to the practice. The subject\u2019s age and weight are given as a means of control. The measurements are in millimeters.\nTable VI.\nIncrease in arm girths.\n\t\t\tBiceps.\t\t\t\tForearm.\t\t\t\nSubject. Age.\t\tRight.\t\tLeft.\t\tRight.\t\tLeft.\t\tWt. in kilos.\n\t\tC.\tR.\tC.\tR.\tC.\tR.\tc:\tR.\t\nG\tf Initial.\t283\t228\t274\t226\t259\t255\t256\t246\t56-3.\n28\t] Final.\t288\t232\t269\t226\t260\t255\t254\t246\t56.8\n\t(Gain.\t5\t4\t\u2014s\t0\ti\t0\t\u20142\t0\t0.5\nH. 1\tf Initial.\t270\t238\t265\t237\t252\t247\t250\t248\t66.6\n26 'j\t: Final.\t283\t246\t271\t241\t265\t257\t260\t252\t67.2\n\t[ Gain.\t13\t8\t6\t4\t13\t10\t10\t4\t0.6\nB. I\tf Initial.\t287\t249\t285\t252\t246\t237\t260\t252\t75-7\n29 j\tFinal.\t293\t255\t296\t256\t259\t249\t265\t257\t75-r\n\t[ Gain.\t6\t6\tii\t4\t13\t12\t5\t5\t\u20140.6\ni. I\t' Initial.\t230\t275\t317\t275\t283\t275\t281\t272\t71.6\n26 j\tFinal.\t238\t281\t320\t277\t283\t277\t277\t270\t71.6\n\t. Gain.\t8\t6\t3\t2\t0\t2\t\u20144\t\u20142\t0\nJ. J 26\t1\t\u201d Initial.\t310\t265\t302\t260\t270\t262\t265\t255\t69.3\n\tFinal.\t312\t264\t302\t262\t273\t265\t260\t260\t69-3\n\tGain.\t2\t\u2014i\t0\t2\t3\t3\ti\t5\tO\nK. !\tr Initial.\t276\t235\t260\t220\t252\t240\t243\t232\t56.1\n24 I\tFinal.\t280\t239\t262\t230\t251\t240\t246\t235\t56.1\n\t_ Gain.\t4\t4\t2\t10\t\u2014i\t0\t3\t3\tO\nAv. gain.\t\t6-3\t4-5\t2.8\t3-6\t4.8\t4-1\t2.1\t2-5\t0.1\n\t\tC =\tContracted.\t\t\tR = Relaxed.\t\t\t\t\nThe results showed that the practice had effected an increase in the girth measurements. For example, G. \u2019s initial measurement for the right biceps contracted was 283, relaxed it was 228. His final measurements for the right biceps were, contracted 288, relaxed 232. The gain in the biceps contracted was 5'\u201dmand relaxed 4mm, as the result of his two weeks\u2019 practice.\nThere was no marked gain in the weight of any of the subjects that might account for the increase in girth. The average gain was o. 1 kilo, which is insignificant, while B., who lost weight, made as large gains in girth as any.\nThe gains in girth measurements were greatest in this order ; right biceps, right forearm, left biceps, left forearm. The right arm gained by direct practice but though the right increased twice as much as the","page":20},{"file":"p0021.txt","language":"en","ocr_en":"Researches in cross-education.\n21\nleft, still the left made marked gains, and there seems to be no doubt that there had been a transference of the effects of practice on the one side, to the unpracticed other side. Among the girths of right biceps there is only one loss recorded. This is for J., who made only small gains in all of his girths. For left biceps there is one loss recorded, that of G. This, as well as other irregularities in the case of G., to be mentioned later, may be explained from the fact that he misunderstood the instructions given, and during his practice period, stopped his usual exercise. For the right forearm one small loss is recorded, and for left forearm three losses.\nThe results, though exhibiting variations and exceptions, show very clearly that exercise producing a gain in girth of one arm causes a similar though smaller gain in the other.\nSymmetrical development.\nHere, it would seem, is a provision by nature to prevent a one sided development. If the right side of the body received all the benefit of its excess of exercise over the left, it would tend to outgrow it in much greater proportion than is actually the case.\nThere is really very little difference between the sizes of the right and left arms. This is especially true if the measurements are taken with the muscles relaxed. There is a greater difference when contracted, as if a stronger stimulus to action could be sent to the right than to the left. As a proof of this point the measurements of one hundred Yale Freshmen were averaged, and the following results obtained.\nRight biceps,\tcontracted,......................................296.04\u2122\u201c\nLeft \u201c\t\u201c\t.......................................282.57\nDifference, .................................................. . 13.47\nRight biceps,\trelaxed,.......................................248.95\nLeft \u201c\t\u201c\t.......................................242.41\nDifference,.................................................... 6.54\nThe difference in girth between the right and left biceps, contracted, is I3-47) but when relaxed, the difference is only 6.54. If we subtract the girths with muscles relaxed, from the girths with muscles contracted, we find a difference in the right arm of 47.09, in the left of 40.16, These last figures may represent the contracting power of the muscles, and if so, the ability of the left arm is about 85 \u00b0Jo that of the right.\nThis difference in the extent to which the muscles are contracted is shown very clearly in my own case. This measurements are : right biceps contracted 330\"'\u201c, relaxed 275'\"\"' ; left biceps contracted 317\u201c\u201c\u201c, re-","page":21},{"file":"p0022.txt","language":"en","ocr_en":"22\nWalter W. Davis,\nlaxed 2 75mm. The measurements are the same for the muscles in the relaxed condition, but when contracted the difference is i3mm, in favor of the right. There is a difference also, in the contours and in the lengths of the two biceps. The right is shorter and more clearly defined, an indication that it has greater power of contraction.\nIncrease in endurance.\nIn the initial test the subject raised the weight until forced to stop on account of fatigue or pain, though the test was not carried to the very, extreme of endurance. The number of flexions made is given in Table VII.\nTakle VII.\nNumber of fiections made.\n\tR ,\tL\t\t\tn\tL\nInitial.\t180\t100\t\tf Initial.\t250\t223\nFinal.\t1000\t300\ti. -\tJ Final.\tIOOO\t250\nGain.\t820\t200\t\ti Gain.\t~75\u00b0\t27\nInitial.\t100\t80\t\tf Initial.\t200\t75\nFinal.\t1050\tno\tj- -\tJ Final.\t600\t300\nGain.\t950\t\t\t1 Gain.\t400\t225\nInitial.\t100\t125\t\tC Initial.\t136\t93\nFinal.\t1000\t200\tK. \u25a0\tJ Final.\t860\t607\nGain.\t900\t75\t\t1 Gain.\t724\t\nThis table also gives the number of flexions made in the final test. The weight which in the initial test was heavy enough to reduce either arm to a condition of fatigue after a few minutes\u2019 w'ork, was not able to so effect the right in the final test, though soon fatiguing the left arm. The practice had so inured the right arm to fatigue that with the given weight and time of flexion the work could be kept up almost indefinitely. At one thousand flexions the fatigue was scarcely noticeable, hence the test was not continued.\nIt is clear that the right arm had developed remarkably in endurance. K. who is slight and not of rugged health, at the end of the final test for right arm, said his arm was not tired in the slightest degree, although he was apparently almost overcome by the general effects of fatigue. The left arm also had gained in endurance though not to so great an extent. The average number of flexions for the left arm at the initial test was 119, at the final test, 297, a gain of 178 or 150%. We conclude that while the left had gained very materially, both in size and endurance, from the practice of the right, there was still a lack of that fineness of condition which seems dependent upon actual exercise of the muscle itself.\nThere is an entire lack of correspondence between the increases in","page":22},{"file":"p0023.txt","language":"en","ocr_en":"Researches in cross-education.\n23\ngirth and in power of endurance. In fact the six subjects illustrate two types, differing widely in these respects. G., J. and K. belong to a type showing very little gain in girth, but exhibiting a marked increase in endurance of the left arm. H., B. and I. make large gains in girth for both right and left arms, but little increase in the endurance of the left arm.\nTable VIII.\nComparison between girth measurements and pcnver of endurance.\nG.\tGirth Right biceps. 5\tgains. Left biceps. \u20145\tFlexion gains, Left arm. 200\nJ-\t2\t0\t225\nK.\t4\t2\t5H\nAverage\t3^\t\u2014i\t313\nH.\t13\t6\t3\u00b0\nB.\t6\t11\t75\nI.\t8\t3\t27\nAverage\t9\t6%\t44\nIn Type A (Table VIII. ) there is an average gain of\tin the\ngirth of the right arm and a loss of iram, in that of left ; while the flexions for left arm increase by 313. In Type B the girth gains are large, but the gain in flexions is only 44. The two types are, then, very clearly defined and separated from each other ; while the similarity of the individual results in each type is quite close. For example, G.\u2019s gain in right biceps is less than any in Type B. The same comparison can be made successfully with any individual whatsoever in either type. The facts noted are therefore worthy of the highest consideration.\nWhy such results are produced is not clear. Though it has often been noticed that a larger muscle is not always capable of greater strength and effectiveness than a smaller one, still one would think that there ought to be a correspondence in the same individual at different times between the size of his muscles and their endurance, and that if a marked gain in size occurred for any reason there should be also a marked gain in endurance. In Type A the nutrition has effected such a change in the muscle cells that they have gained endurance, ln Type B the tissue that has been added may be fat, or some other constituent that has not been worked into the life of the muscle cell.\nIncrease in strength.\nThe strength of forearm was taken at both initial and final tests by means of an ordinary oval spring hand-dynamometer. The subject was given two trials with each hand and the highest mark made by each hand","page":23},{"file":"p0024.txt","language":"en","ocr_en":"24\nWalter W. Davis,\nrecorded. No practice was given the subject in gripping the dynamometer, the object being to determine if there was any increase in strength of the right forearm due to general improvement in the nutrition of the arm. This being found, it remained to be determined whether there was a similar increase in the strength of the left. It has already been pointed out that as fatigue came on there was a certain amount of clenching of the hand in holding the dumbbell. One would reason that the muscles of the forearm would be developed and so an increase of strength would result. This is found to be true. Table IX. shows that this increase is\nTable IX. Increase in Strength. Pressure of\nPressure of\n\tdynam.\tin kilos.\t\t\tdynam. :\tin kilos.\n\tR\tL\t\t\tR\tL\nf Initial.\t41.8\t43-6\t\t( Initial.\t54-1\t49.0\nG.\t-j Final.\t45-4\t40.8\tI.\t\u25a0j Final.\t56.8\tS3-1\n( Gain.\t3-6\t\u2014 2.8\t\t( Gain.\t2.7\t4-i\n( Initial.\t46.5\t35-4\t\tf Initial.\t38-6\t38.2\nH.\t\\ Final.\t54-1\t48.9\tJ-\tGain.\t44-5\t41.8\n( Gain.\t7.6\t13-5\t\t( Final.\t5-9\t3-6\n( Initial.\t38.6\t39-5\t\t( Initial.\t46.5\t41.8\nB.\t-j Final.\t54-5\t50.0\tK.\t-j Gain.\t44.2\t45-4\nf Gain.\t15.9\t10.5\t\t( Final.\t\u2014 2.3\t3-6\n\t\t\t\tAverage gain\t5.56\t\t5 41\ntransferred to the left side.\t\tThe\taverage gain of the right arm\t\t\tis 5-56\nkilos., of the left\t5.41 kilos, or\t\tnearly\tas much.\tThis corresponds\t\nclosely with the figures obtained by Dr. Anderson, where the dynamometric pressure itself was practiced. He found, with practice of the right hand alone, a gain in the right of 11.7 pounds, in the left of 13.2, the gain in the left being the greater.\nThere were two failures to make gains in strength of grip. G., who, as we have before pointed out, neglected to follow instructions exactly, made no increase in the left forearm ; and K., who showed no increase in girth of right arm, failed there also to increase in strength.\nIf we compare the gain in girth of forearm' (hand clenched) with the gain in pressure, we find a close correspondence. The six subjects again fall into two types, not so clearly defined, however, as those in Table VIII. In Type C (Table X.) are placed H., B. and J., who show the largest gains in girth and also in the dynamometric pressure. Though there are some partial variations from the type, the averages prove the point very conclusively. The average gains in girth and in pressure in Type C are all large ; in Type D they are all small, zero or minus.","page":24},{"file":"p0025.txt","language":"en","ocr_en":"Researches in crass-education.\n25\nA test of endurance differs materially from one of strength. The -former requires a succession of small impulses for action, extending over a long period of time ; the latter, a strong impulse for action for only a\nTable X.\nComparison between girth measurements ani dynamometric pressure.\n\t\t\tGirth\tgains.\tDynamometer gains.\t\n\t\t\tForearm.\t\t\t\n\t\tR\t\tL\tR\tL\n\tH.\t13\t\tIO\t7.6\t13-5\nType C.\tB.\t13\t\t5\t159\t10.5\n\tJ-\t3\t\tI\t5 9\t3-6\n\tAverage\t9%\t\t5 %\t9.8\t9.2\n\tG.\tI\t\t\t2\t3-6\t\u20142.8\nType D.\tI,\tO\t\t\u20144\t2.7\t4-1\n\tK.\t\t1\t\t3\t\u20142-3\t3-6\n\tAverage\tO\t\t\u2014 I\ti-3\t1.6\n\u25a0moment of time. The\t\ttwo\ttests\tare very unlike, and\t\tmay require\n\u25a0development of entirely different factors.\nThe effect of practice oti the ability to resist fatigue and pain.\nSome important facts were noted from the observations made in respect to fatigue, pain and soreness, due to exercise ; and also in respect to the condition of the muscle, before and after practice. . At the initial test the fatigue was local for both right and left arms, and was limited to pain in the attachments of the biceps muscles at the shoulder and elbow. The biceps itself did not tire. No general feeling of fatigue was experienced. For a few days after the initial test the muscles and tendons \u2022of both arms were very sore, so that practice was quite materially interfered with. No marked difference could be detected, by sight or pressure, between the muscular condition of the right and left arms.\nAt the final test fatigue was more general. K. was completely \u201ctired \u2022out.\u201d Subject I. \u201cached in knees and back,\u201d was very nervous and \u2022could not sleep the first night after the test ; his arms felt numb with a tendency to \u201cgo to sleep.\u201d J. experienced a great thirst during the test. When local pain was felt at all it was generally in the tendons, as at the initial test. Very little soreness either in the right or left arm was experienced as a result of the final test. When the muscles were pressed with the finger a slight difference could be noted between the \u25a0condition of the arms, the right biceps being the firmer. The facts above","page":25},{"file":"p0026.txt","language":"en","ocr_en":"2 6\nWalter W. Davis,\nnoted do not hold for all of the subjects. The data could hardly be exhibited in a table, so they have been summed up in general.\nWe may draw several conclusions from the facts observed in regard to fatigue, pain and soreness, (i) Practice so inured the right arm to its-work that in the final test general fatigue came on before local fatigue. This hardening process was transferred in a striking degree to the unused side. In a work of endurance the tendons seem to weaken before the muscles themselves. (2) By practice the right arm reached such a condition that the after-effects of local soreness from continued exertion were avoided. This was found equally true of the unused side. (3) As far as could be judged from the examination by pressing the muscles with the fingers and from the amount of work done by both arms, the right arm. had attained a fineness of condition not shared in by the left.\nThe immediate effects of exercise on girth measurements.\nIn order to determine if the blood circulation on one side of the body varied with the exercise of the other side, measurements of the biceps, contracted and relaxed, were taken in the order R, L, before the exercise\nTable XI.\nGit \u00eeh measurements before and after exercise.\n\t\tBiceps.\t\tBiceps.\t\tGain\t\tBiceps\t\tGain\t\n\t\t1st Meas.\t\t2d Meas.\t\tover\t1st.\t3d Meas.\t\tover\tist.\n\t\tR\tL\tR\tL\tR\tz\tR\tL\tR\tL\nG.\tC\t288\t269\t293\t268\t5\t\t1\t293\t277\t5\t8\n\tR\t232\t226\t245\t228\t13\t2\t240\t240\t8\tH\nH.\tC\t283\t271\t298\t268\tiS\t\u20143\t290\t273\t7\t2.\n\tR\t246\t241\t256\t239\tIO\t\t2\t261\t246\t5\t5\nB.\tC\t2 93\t296\t3\u00b07\t300\t14\t4\t296\t3\u00b03\t3\t7\n\tR\t255\t256\t267\t255\t12\t\t1\t260\t270\tS\t14\nL\tC\t338\t320\t348\t320\tIO\tO\t347\t33\u00b0\t9\tIO\n\tR\t281\t277\t294\t276\t13\t\t1\t291\t292\tIO\t15\nj-\tC\t312\t302\t318\t3\u00b04\t6\t2\t314\t315\t2\t13\n\tR\t264\t262\t274\t260\tIO\t\t2\t265\t270\tI\t8\nK.\t\u00c7\t280\t262\t290\t261\tIO\t\u2014 I\t277\t270\t\u20143\t8\n\tR\t239\t230\t252\t231\t13\tI\t243\t238\t4\t8\n\t\t\t\t\tAverage C\tIO\t1 *\t\tAverage C 41/\t\t8\n\t\t\t\t\tR 12\t\t\u20143\t\t\tR 5)4 10%.\t\nC\u2014Contracted. R\u2014Relaxed.\nwith the dumbbell ; then in the order R, L, immediately after the test with the right arm; and finally in the order Z, R, immediately after the test with the left arm. The measurements given in Table XI. do not show a corresponding variation in both members.\nIn the second set of the measurements there was an average increase o\u00a3","page":26},{"file":"p0027.txt","language":"en","ocr_en":"Researches in cross-education.\n27\nI.\t0 mm, or 3%, in the girth of the right biceps contracted, and of 12\u2122, or 5%, in the same relaxed. There was no increase in the left arm, but rather a decrease in size. The fact that the increase in right arm was greater in the relaxed condition, may be explained mechanically. The surplus of blood due to exercise was actually squeezed out of the muscle when it was rigidly contracted.\nThe increase in the size of the right arm is probably due to two effects of exercise : ( 1 ) the rush of blood to the muscle, shown by the distention of the superficial veins; and (2) the swelling of the muscle due to the production of heat and waste products. After K. had completed his test, a marked difference in temperature was noted between the biceps and the triceps. The fact was evident even to the sense of touch. The triceps felt cold in the comparison.\nIn the third set of measurements taken immediately after exercising the left arm, this member was found to have increased in girth, while the right, due to its quiescence, had already lost much of its former gain. In\nJ.\tand K., who made the highest number of flexions with the left arm, the former increase made by the right is practically all lost.\nThree facts would seem to show that the circulation of the side not exercised does not tend to vary in accordance with that of the side exercised : ( i ) the negative results in the left arm measurements taken after the exercise of the right ; (2) the rapid decrease in girth of right arm, after its exercise, even though the left was then exercising ; (3) the very manifest difference between the temperature of used and unused muscles in close proximity. The facts would indicate rather a variation of blood circulation in the opposite direction.\nTable XII.\nAmount of Practice.\n\tTotal number\n\tof flexions.\nG.\t4900\nH.\t5500\nB.\t3100\nI.\t3900\nJ-\t1050\nK.\t6300\nAverage\t4125\nDays\tAv. flex\u2019s, per\nof practice.\tday.\n12\t408\n12\t458\n12\t258\n12\t32s\niS\tIIS\n21\t3\u00b0\u00b0\nh1A\t310\nTime\nof exercise. Evening. Evening.\nEve. and mom. Eve. and morn.. Evening. Morning.\nAmount of practice.\nFor the practice experiments the instructions were not to tire or overwork the muscle but to exercise lightly and frequently. To show the","page":27},{"file":"p0028.txt","language":"en","ocr_en":"-28\nWalter W. Davis,\namount of practice done Table XII. was prepared from the subjects\u2019 notes. The duration of practice averaged 14*^ days. The average member of flexions in each day\u2019s practice varied from 115 to 458, the total average being 310. The time of exercise was either early morning or late evening. No correlation could be discovered between the length and time of practice and the girth gains, or the number of flexions and the girth gains. The two subjects, J. and K., who continued the practice over the longest -period of days made the greatest gains at the final test in the number of flexions of the left arm. The average of the periods of practice was 19% \u25a0days and their average gain in flexions, 369. For the other subjects the period of practice was 12 days and their gain in the left arm flexions only 83. This indicates that the transference of the effects of practice is not immediate, but occurs after the effects are noticeable on the side practiced.\nTablf. XIII.\nSubjects. Conditions.\nComparison of results.\nResults.\n\tA\tB\tc\tD\t\t\n\t\t\t\tR\tL\tR\nG.\t28\t12\t408\t5 -\t-5\t\u2022 I\nH.\t26\t12\tGO LT) rj-\t13\t6\t13\nB.\t29\t12\t258\t6\t11\t13\nI.\t26\t12\t325\t8\t3\t0\n\u2022 J-\t26\t18\t115\t2\t0\t3\nK.\t24\t21\t300\t4\t2\t\u2014i\nAverage 20\\\t\t\t310\t\t\u00bb1\t4f\nA,\tsubject\u2019s age.\nB,\tpractice period in days.\n<C, daily average number of flexions.\nD, girth gain of biceps, contracted, in mm.\nF\tF\nL\tR\tL\tR\tL\n\u20142\t820\t200\t3-6\t\u20142.8\n10\t95\u00b0\t30\t7.6\t13-5\n5\t900\t75\t15.9\t10.5\n\u20144\t75\u00b0\t75\t2.7\t4-i\nI\t400\t225\t5-9\t3-6\n3\t724\t5H\t\u20142-3\t3-6\n2i\t757\t1 00 1 \u00a3\u2022\t5-56\t5 41\nE,\tgirth gains of forearm, contracted.\nF,\tgains in number of flexions.\nG,\tgains in dynamometric pressure, in kilos\nSummary.\nTable XIII. is intended to exhibit at a glance the important conditions \u25a0of the dumbbell test and the results obtained in relation to the amount of practice. For example, H., 26 years of age, during a period of 12 days, by lifting a weight of 2^ kilos, with the right arm 458 times each day, increased the girth of the right biceps by 13\u00b0\"\u201c; of left by 6mm. The averages give the results which may be expected with the given conditions. The figures would vary undoubtedly with another set of subjects or should any of the important conditions be changed. The general condition to be emphasized is that by practice of one side of the body","page":28},{"file":"p0029.txt","language":"en","ocr_en":"Researches in cross-education.\n29-\nin muscular power the other side shares in the gain in size, strength and endurance.\nIV. Accuracy of voluntary effort.\nLunging at a target with a fencer\u2019s foil was chosen as a suitable exercise to educate the subjects in accuracy and coordination. It is a complicated movement, involving the simultaneous action of many muscles-and muscle groups. These coordinated muscles are in some cases remote from one another. Accuracy in the movement may be cultivated to considerable fineness. Attention is essential to such accuracy.\nThe lunge used in this work was that taught by the French school of fencing. It is described as follows : ( 1 ) The subject\u2014when lunging right-handed\u2014at the command \u201cReady,\u201d assumes a position with the right side to the target, left foot parallel to the target, right foot in advance a short step and at right angles to the left, knees slightly bent, body perpendicular, left arm bent over the head, right arm with foil in hand supine, right elbow bent and foil pointed at the target. (2) At the command \u201cLunge,\u201d the following movements are executed simultaneously: the whole body is thrown forward toward the target but the trunk is still perpendicular ; the right foot is advanced a long step, but with knee still bent ; the left foot is kept in its place and the left leg extended ; the left arm drops to the back ; the right arm is extended.\nIn this way the foil is advanced at the target. This lunge was taught as rapidly as possible during the practice. It required about a week for the subjects to learn it with any degree of grace and precision. They were allowed to practice the movements, right-handed, in their rooms but no records of accuracy were made except at the regular practice hour, in the presence of the investigator. The practice continued in most cases, for 10 days.\nj=~\nFig. 3.\nApparatus.\n\u25a0 rA tack was soldered to the point of an ordinary fencer\u2019s foil. . (Fig. 3. ) The tack was filed to a sharp point of 3\u201c\u201c length. A rubber cap was adjusted firmly over the end of the foil so that the point of the tack was 1 en. When the foil was thrust against the target, the rubber was compressed so that the tack protruded enough to pierce the paper; the C aStlcitJr \u00b0* '\u25a0he rubber, as the foil was drawn away, preventing any tear-","page":29},{"file":"p0030.txt","language":"en","ocr_en":"3\u00b0\nWalter W. Davis,\ning of the paper that otherwise would have been caused. The target (Fig. 4) was devised by Dr. Scripture. It was composed of two boards 6o0m square, and 2cm and iom thick. The lighter swung on the heavier one by a hinge at the top, thus forming a cover over it. A disc 47\u201c\u201d1 in diameter was cut out of the thin board so that the center of the circle and the center of the boards coincided. At the ends of the perpendicular and horizontal diameters of the circle, four small nails with sharpened tops were inserted into the back board. Thin white wrapping paper was used for targets. To place a target the thin cover-board was raised, the paper was pressed down on the four nail points, the cover was lowered and firmly clamped. The whole target was\nFig. 4.\nsecurely fastened against the wall at the height of 1^ m. To center the target : a stick (Fig. 4) was fitted into two sockets on the cover. A nail with a sharp top was fixed in the middle of the stick, so that it","page":30},{"file":"p0031.txt","language":"en","ocr_en":"Researches i/i cross-education.\n31\n-coincided with the center of the target. When the paper had been adjusted, the stick was placed in the sockets and by pressure on its upper surface the nail on its lower surface was driven through the paper into the center of the target. The stick was then removed, and a black pin i5mm long, with a head 2y2mm in diameter, was inserted into the center to serve as a point to aim at. For each subject a distance from the target was chosen which seemed best adapted for his reach with the foil. This distance remained constant for him during the entire practice.\nCharacteristics of the subjects.\nFour of the subjects were college freshmen, one a graduate student, and one a draughtsman.\nTheir individual characteristics may be indicated in the following manner :\nI. Age, twenty-six. Graduate student. Temperament, nervous. Gymnast and athlete.\nL.\tAge, seventeen. Temperament, nervous. Ambidextrous. General training in athletics.\nM.\tAge, seventeen. Temperament, phlegmatic. \u2019 No gymnastic training.\nN.\tAge, twenty-two. Draughtsman. Temperament, motor. General training and especially in gymnastics. Ambidextrous.\nO.\tAge, eighteen. Temperament, motor. No systematic bodily training.\nR. Age, eighteen. Temperament, nervous. No special training except farm work.\nThe average age of years should be favorable for increase in accuracy and coordination.\nMethod of experiment.\nFor the test the subject was allowed either to dress in a gymnasium suit or to wear his ordinary clothes. In the latter case, however, the coat, collar and tie were removed to allow of free movement in lunging. After the manner of dressing had been chosen, it remained the same for each subject throughout the tests and all the practice exercises.\nNone of the subjects had fenced previously to the experiments. When the subject came into the room for the first time, the lunging movement was described carefully, but briefly, and each was allowed two or three preparatory lunges\u2014right-handed\u2014before a record was taken. Then, at the command \u201cReady,\u201d he assumed the position, and at \u201c Lunge,\u201d he thrust the foil at the target. The observer stood ready with his pencil","page":31},{"file":"p0032.txt","language":"en","ocr_en":"32\nWalter IV. Davis.\nand marked the hole in the paper with a figure r. The lunge was immediately repeated until a record of ten thrusts was obtained. The paper was then removed and a fresh one placed in the target. Any important observations were also noted down. After five minutes the experiment was repeated with the left hand.\nThe subject was practiced for ten days in thrusting with the right hand. Ten thrusts were allowed for each daily practice. At the end of the practice period, the initial test was repeated to compare gains in the right and left arms. Notes were also taken in respect to improvement in form of lunging. The tests were all taken about 3 P. M., and for each subject all the conditions were kept as nearly as possible the same.\nResults.\nThe figures tabulated in Table XIV. are distances in mm. from the center of the target and are the averages for ten thrusts. Subjects L. and N.\nTable XIV. .\nIncrease in accuracy of lunging.\n\t\tInitial.\t\tFinal.\t\tGain\t\tRelative\tgain.\nAge.\t\tR\tL\tR\tZ\tR\tZ\tR\tZ\nI.\t26\t21.8\t46.0\t16.8\t34-5\tS-o\t11.s\t0.22\t0.25\nL.\t17\t36.2\t39-9\t25-4\t27.2\t10.8\t12.7\t0.29\t0.30\nM.\t17\t49.8\t72.8\t25-3\t44.4\t24-5\t28.4\t0.49\t0-39\nN.\t22\t56.2\t50.4\t25.7\t35-4\t30.5\t15.0\t0-54\t0.29\n0.\t18\t80.2\t86.5\t25.5\t32-7\t54-7\t53-8\t0.63\t0.62\nR.\t18\t59-2\t47-9\t27-5\t44-9\t31-8\t3-o\to-53\t0.06\nAverage\t'9'A\t50-5\t57-2\t24-3\t36-5\t26.2\t20; 7\t0.51\t0.36\nare practically ambidextrous, and in right and left initial tests they give average results not very widely separated. R. shows greater accuracy with the left than with the right although he is right-handed. In the final tests the right hand is more accurate in all cases. In three cases the left has made the greater gain in millimeters ; in the other three, the right. Four subjects made greater relative gains with the right arm ; two, with the left arm. The final averages show that the right arm is the more accurate. In the initial tests the average difference between right and left is 6.7mm. In the final tests the difference is i2.2mm. Hence the right has made the greater average gain, the difference being 5.5\"\u201d\u201d in favor of the right.\nTable XV. gives the probable error, expressed in millimeters and also in per cent, of subjects O. and I. The point to be noted especially is","page":32},{"file":"p0033.txt","language":"en","ocr_en":"Researches in cross-education.\n33\nthat the probable error of the left arm has decreased as well as that of the right, though in each case the decrease is greater in the right.\nTable XV.\nDecrease of probable error.\nProbable error.\t\tProbable error in %.\t\t\tProbable error.\tProbable error in %.\t\nR\tZ\tR\tZ\t\tR\tL\tR\tZ\ni\t12 46\t12.02\t15-5\t\u00bb3 9\tO / In-\t31-2\t4-92\t14-3\t16.9\n2 86\t3\t11.2\t11.\tU'\\F.\t1.84\t3.74\t10.9\t10.8\nFigs. 5 and 6 were constructed to illustrate the increase in accuracy\nLeft. Initial\nFig. 5.\nH'ftit, Initial.\ndue to practice in lunging. The cuts exhibit the facts given in Table XIV. The average distances from the center in the initial tests are indicated by the outer circles ; the distances in the final tests by the inner ones.\nThe effect of previous training.\nThe fact that the left does not gain so much as the right is emphasized by the consideration that, since the right arm is. to begin with, more accurate than the left, there is less opportunity for it to make large gains. There is a point beyond which increase in accuracy is extremely slow. The largest gains were made by subject O. whose initial records were the most inaccurate of all. The smallest gains were made by subjects I. and L. whose initial records were the most accurate.\nSubject I., who is a trained man physically through gymnastics and athletics, made the most accurate average initial record. He was able 3","page":33},{"file":"p0034.txt","language":"en","ocr_en":"34\nWalter W. Davis,\nafter 15 days\u2019 practice to lower the record of the right arm by 5\u201c\u201c, and that of the left arm by n.5mm. M. and O., who were very inaccurate at the initial test, had had no special bodily training ; at this particular test of accuracy they made great improvement. The others did not exhibit striking characteristics in the records; they were men of average bodily, training. An exception to the preceding statement is to be made in the case of R., in whose case the left hand was superior to the right in the initial test and made only a small gain.\nFig. 7.\nFig. 8.\nX, upper line, serial number of thrust.\nX,\tlower line, successive steps in subject\u2019s practice.\nY,\tdistance from center of target.\nIt is probable that accuracy, steadiness and coordination, when secured through any' means of training, make their influence felt in any test that requires such qualities for its successful performance.","page":34},{"file":"p0035.txt","language":"en","ocr_en":"Researches in cross-education.\n35\nFig. io.\nX, upper line, serial number of thrust.\nX, lower line, successive steps in the subject\u2019s practice. V, distance from center of target.\nInfluence of practice on average accuracy.\nThe curves in Figs. 7, 8, 9, and 10 were made to illustrate the average accuracy of the successive thrusts in the initial and final tests. X indicates the number of the thrust in the series of ten, and Y the distance in millimeters from the center of the target. The initial and final records of subjects I., M., O. and R. were averaged to form the curves, the records of L. and N. having been cast out because these subjects were ambidextrous.","page":35},{"file":"p0036.txt","language":"en","ocr_en":"36\nWalter W. Davis,\nIn Fig. 7 (initial test for the right hand lunge) the curve is irregular, reaching its greatest inaccuracy at the fourth thrust. At the final test for the right hand lunge (Fig. 8) the curve is more regular, but resembles the initial curve in still being most inaccurate at the fourth thrust. The curve for the initial test for the left hand lunge (Fig. 9) shows an increase in accuracy. The curve for the final test of the left hand lunge (Fig. 10) has been changed very materially by the practice of the right arm. The most important fact shown by the curves is that by the right arm\u2019s practice, both right and left have gained greater steadiness and uniformity. In the final tests each thrust is more nearly an average thrust.\nCoordination of Movement.\nAccuracy and coordination are closely connected. Accuracy depends in great part upon a dedicate coordination of muscle groups and of motor centers. A few facts in respect to the subject\u2019s \u201c form\u201d during his performance of the lunges are here presented; the term \u201cform\u201d is used to mean the grace and precision with which the movement is executed.\nWhen the foil was handed to the subject for the first time, he was instructed how to use it right-handed. After the short rest between right and left tests, he was asked to lunge left-handed, but no additional instructions were given. In most cases there was no confusion resulting from the change of side, though the form was not so good. At the final test the same points were observed, with the following results.\nI. Movements with the left hand were executed correctly and in order, but a certain awkwardness was experienced.\nL.\t(ambidextrous). Form almost perfect with the left hand.\nM.\tWas not able during the practice to learn to dispose of the left hand properly. He always forgot to lower it when executing the lunge. This same trouble was experienced at the final test with both right and left hands. Otherwise the form was good, both right and left.\nN.\t(ambidextrous). He remarked that it was easier to lunge left-handed than right-handed.\nO.\tForm not so good left-handed as right-handed.\nR. Not at ease left-handed. This shows in the records. Very little gain was made for the left arm.\nIn general, the movements necessary to the lunge are learned for the left side by practicing the right. Yet there is a perfection of grace and a fineness of coordination, that are attained only by the actual practice of the member under consideration.","page":36},{"file":"p0037.txt","language":"en","ocr_en":"Researches in cross-education.\n37\nAccuracy of skilled fencers.\nThe records of four experienced fencers, all of whom teach the art, were secured and are shown in Table XVI. Of these F.L., N.L. and G.M. teach with the foil in the right hand and have never fenced left-handed. WA. though right-handed, teaches with the foil in the left hand. For\nTable XVI.\nA comparison of the accuracy of skilled and unskilled fencers.\nAverage accuracy. Average of R and' L.\n\tR\tL\t\nF.L.\t36-3\t63-3\t49.8\nN.L.\t42.6\t58-9\t5\u00b0-7\nG.M.\t4Q-5\tSi-6\t46.0\nAverage\t39-8\t57 9\t4878\nW.A.\t24.9\t23.8\t24-3\nSix subjects of Table XIV. / In'fiab J\tl Final.\tSo. 5 24-3\t57.2 36.5\t53-8 3\u00b0-4\ncomparison with these records, the table gives those of the six subjects of investigation. The experienced fencers who had taught right-handed were not able to equal in accuracy the six subjects who had been practiced for ten days ; in fact they were not greatly better than those subjects at the initial test. W. A. is physically a perfectly trained man, and a teacher of gymnastics. These facts, together with his left-handed teaching, probably account for his accuracy. The inaccurate records of F.L., N.L. and G.M. may be explained in two ways. ( i ) In fencing, accuracy is not cultivated to any great extent,1 but skill in parrying and the ability to get the thrust in at the right moment are considered the essential points. ( 2 ) Much of the accuracy of the six subjects is due to their practice under exactly the same circumstances. Possibly skilled fencers would be enabled to make unusually accurate records by a few days of similar practice.\nRatio of accuracy between right and left arms.\nTable XVII. shows the ratios in accuracy between right and left arms. With one exception, the ratio has increased, as the result of the practice with the right arm. It is significant that the average final ratio of the six subjects is nearly the same as the average ratio of F.L., N.L. and G.M. For W.A. who fences with either the right or the left hand, the right and left sides are practically equally accurate.\n'Scripture, Tests of mental ability as exhibited infenci-g, Stud. Yale Psych. Lab. 1894 II 123.","page":37},{"file":"p0038.txt","language":"en","ocr_en":"3\u00ab\nWalter W. Davis,\nTable XVII. .\nInitial ratio.\tFinal ratio.\n\tR\tL\tR\tL\nI.\t1\t2.il\ti\t2.05\nL.\tI\t1.02\t1\t1.07\nM.\ti\t1.46\ti\ti 75\nN.\ti\t0.89\ti\t1-37\nO.\tI\t1.08\ti\t1.28\nR.\tI\t0.80\ti\ti 63\nAverage\ti\tII3\ti\t1 50\nF.L.\t\t\ti\t1-74\nN.L.\t\t\ti\t1.38\nG.M.\t\t\ti\t1.27\nAverage\t\t\ti\t\u00cf-45\nW:A.\t\t\t\u25a0I\t\u00b0-95\nIn the case of the skilled fencers, very little difference could be detected between the \u201c form \u201d of the right and the left sides. The fencers themselves were surprised to find it so easy to lunge left-handed. Not only was there no apparent awkwardness, but the new movement was executed with a considerable degree of precision and accuracy.\nFatigue.\nThe test was too short to allow the element of fatigue to enter to any extent. In many individual records, however, fatigue, or what produced similar effects, was present. Figs, n, 12 and 13 are curves constructed from individual records. X is the number of the thrust in the series, V, the distance of the thrust from the center of the target. The curve in Fig. 11, a practice record of subject L., shows a tendency to improvement in accuracy which is regular till the eighth thrust. After this, fatigue seems to come in and the accuracy decreases with the tenth. In Fig. 12 the curve of M. shows improvement till the fifth thrust, in which the center is struck. Fatigue appears earlier in this record and there is a general decrease in accuracy to the end of the record. In no case did the subjects complain of fatigue, but the observer could detect a wavering of the foil point toward the end of records like Figs, n and 12. Though the subject was not conscious of it, the fatigue was evident in the decrease of accuracy and in the unsteadiness of the foil.","page":38},{"file":"p0039.txt","language":"en","ocr_en":"Researches in cross-education.\n39\nFig. ii.\nFig. 12,\n_\tFig. 13.\nX, upper line, serial number of thrust.\nX, lower line, successive steps in subject\u2019s practice. V, distance from center of target.\n1*\u00b0*","page":39},{"file":"p0040.txt","language":"en","ocr_en":"40\nWalter W. Davis,\nt IG. 14.\nIn N.\u2019s fourth practice record, shown in Fig. 13, there is no great variation from the first thrust. After each thrust the subject\u2019s nervous equilibrium is reestablished before the next thrust is made.\nThe form of any individual curve is dependent on three factors. (1) The condition of the nervous and muscular systems. The exercise of\nthe nerves and muscles in lunging tends to improve their condition and hence accuracy is increased. If the system is in prime condition, due to other exercise just previous, this factor does not enter in largely. (2) Fatigue. This factor is more likely to affect the latter part of the curve. (3) Recovery. This factor is in opposition to (2). If the system is able to recover itself completely after each thrust the effects of (2) are counterbalanced. In Fig. 9 the average of left initial test, factor (1) is evident. The accuracy increases from the first to the last because the condition of the nervous and muscular systems is being improved by exercise. In Fig. 12, factor (1) is evident in the first part, factor (2) in the last part. In Fig. 13, factor (2) is counterbalanced by (3).\nTypes of grouping.\nWhen the records were measured the position of each thrust point was taken, and also its angle with a horizontal line passing through the center. The subjects were rather inclined to group their records in a particular manner. Fig. 14 il- L lustr\u00e2tes a type of grouping that was generally given by N. It is the same record as that shown in Fig. 13, and is what may be termed an average record. There are 5 minus and 5 plus, 5 right\tFig. 15.\nand 3 left thrusts, and the accuracy is fairly constant.\nFig. 15 illustrates a different kind of grouping. With the exception","page":40},{"file":"p0041.txt","language":"en","ocr_en":"Researches in cross-education.\n41\nof the 5 th, the thrust-points are in a line, extending from R + to L \u2014. Two of the subjects were quite apt to make such groups.\nIn Fig. 16 are represented both right and left records of W.A., who is equally proficient with both hands. The right hand thrust-points are indicated by crosses, the left by dots. Line AB is drawn from R + to L \u2014 a little to the left of the center. All the right hand thrusts, with one exception, are above to the left of AB. All the left hand thrusts, with one exception, are below to the right of this line. A similar arrangement of thrusts was made by the other skilled fencers, though not in so marked a degree.\nThe following facts may be noted from a study of the groups: (1) Most of the groups are similar to. Fig. 16,\u2014right hand thrusts to the\nFig. 16.\nleft of the horizontal line, left hand thrusts to the right. (2) The tendency to make such groups is more marked in skilled fencers. (3) The tendency increased in the six subjects during the practice. (4) The groups are most marked and distinct in the records of W.A., who has fenced with both right and left hands.\nThere is some evidence, then, to conclude that the influence causing the group records is unequal muscular development. The muscles chiefly used in the lunge are emphasized by practice and by their excessive contraction pull the arm to the other side of the body, thus producing a one-sided record. This unequal muscular development is transferred to the symmetrical muscles on the other side. The influence in","page":41},{"file":"p0042.txt","language":"en","ocr_en":"42\nWalter W. Davis,\ngrouping is, therefore, peripheral and not central or mental. The chief influence at work in regulating the accuracy is central or mental.\nV. Diversion of energy.\nThe following experiments were undertaken with the hope that they might help to furnish some explanation of cross-education.\nApparatus.\nThis was the same as that used in the tapping test first described, except that another key was clamped to the lap board, to allow one for each hand.\nMethod of experiment.\nRecords of five seconds of tapping were taken for the right hand, both tapping alone and also in connection with the other members. The records were taken in the following order : (a) direct, ( x ) right hand alone, (2) right and left hands together, (3) both hands and right foot, (4) both hands and both feet; (b) reversed, in the order (4), (3), (2), (1). In all cases only the right hand made a record. For each subject, two series of records were taken on each of four days. On the first and third days the records were taken in the direct order, and on the second and fourth days in the reverse order. When more than the right hand was tapping no attempt was made to have the different members tap with equal rapidity. The subject was instructed to devote as much attention to one member as to another and to tap as fast as possible with each. He did not know that the tapping of the right hand alone was being recorded. The seven subjects were Divinity and Graduate students of Yale University.\nResults.\nTable XVIII. gives the results obtained for the seven subjects. The figures here are made up from two averages. The average of two-tests in the direct order was combined with that of two tests in the reversed order.\nFrom the table it is evident : ( 1 ) that in general the right hand tapped more rapidly alone than in connection with the other members, (2) this difference in rapidity was not so marked on the third and fourth days-as on the first and second. Even so short a practice made a striking-change. In all cases, in the average of the first two days, the right hand was most rapid alone ; except in the cases of H. and V., this difference was marked. In the average for the last two days, in all but two subjects, H. and V., the right alone was still more rapid though the difference in rapidity is small ; on the contrary H. and V. were able to tap most rapidly","page":42},{"file":"p0043.txt","language":"en","ocr_en":"Researches in cross-education.\n45\nwhen all four members were tapping. The facts were generalized in the final averages. In the total average for the right hand alone the record was 36.9 for the first and second days, 36.3 for the third and fourth days, so that no gain in rapidity was made. The right hand\u2019s total average for tapping in connection with all the other members was for the first days,. 29.7 and for the last, 34.7, a gain of 5 taps for 3 seconds, or 16%.\nTable XVIII.\n7he influence of practice on automatic movements.\nist and 2d days.\t3d and 4th days.\n\t\t(i)\t(2)\t(3)\t(4)\t(I)\t(2)\t(3)\t(4>\n\tH.\t35\t36\t34\t33\t36\t37\t38\t39\n\tS.\t27\t28\t21\t18\t35\t32\t32\t33\n\tT.\t45\t46\t41\t39\t44\t41\t41\t42\n\tV.\t38\t35\t33\t36\t33\t34\t35\t3&\n\tX.\t34\t29\t20\t20\t35\t34\t31\t28\n\tY.\t42\t42\t27\t31\t39\t39\t37\t34\n\tZ.\t36\t31\t32\t28\t31\t31\t27\t28\nTotal average . .\t\t36 9\t35-6\t314\t29-7\t3 6-3\t34.2\t34-8\t34-7\nRelative average .\t\t1.00\tO.96\t0.85\t0 80\tI OO\t0.94\t0 95\t0 95\n( I ) Right hand\talone\t\t\t(3)\tRight\thand with l\u00e7ft hand\t\tand right foot.\t\n(2) Right hand\twith left\t\thand\t(4)\tRight\tband with left hand\t\tand both feet.\t\nThe last line of Table XVIII. shows the changes in rapidity that occurred with a practice of four days, giving the proportional\nrapidity of the right hand under the different conditions. In the tests of the first two days the right hand lost 20% of its speed -while tapping with other members, in the last two days, only 5%. Fig. 17 represents the same facts in the form of a curve. X gives the number of members tapping, and Y, the number of taps in 5 seconds; while only the right hand is being recorded. The continuous line is the average of the first two days, the dotted line that of the last two days. There is a sharp descent in the continuous line, while the dotted line is more nearly straight. This indicates that practice has increased the ability of the right hand to tap in connection\nFig. 17.\nX, upper row, number of members used in tapping.\nX, lower row, number of members in addition to right finger.\nV, number of taps in 5 seconds made by-right index finger, the heavy line representing the average for the first two days of practice, the broken line that for the last two days.\nwith the other members.","page":43},{"file":"p0044.txt","language":"en","ocr_en":"44\nWalter W, Davis,\nWith a longer practice the right hand, in multiple tapping, would undoubtedly excel in rapidity its record while tapping alone. This was true in the case of H. and V. who at first gave four records of nearly equal rapidity.\nRegularity of tapping.\nDuring the last tests of the experiment several of the subjects remarked that the multiple tapping had become easier, that they only needed to \u201c set the machinery going and it went itself.\u201d The experimenter, listening to the tap counter, observed that in multiple tapping the right hand was more regular than when tapping alone. A specimen record is given to illustrate this fact.\n\tist.\t2d.\tAverage.\t\n(4)\t39\t36\tzrA\tTapping very regular.\n(3)\t36\t35\t3$A\tt<\t((\tu\n(2)\t35\t34\t34 A\tTapping irregular.\n(O\t33\t34\t33'A\t<<-\tit\nThe complete record was taken in the reverse order, the observations appended being written down between the consecutive 5 second records. The irregularity is probably caused by too great concentration of energy or attention at one point\u2014too much for the muscles to react to or properly dispose of. Hencfe the time was slower. It does not appear that the cultivation of the power to attend to several members at once is responsible for the increased rapidity in multiple tapping, since there was an actual decrease \"of attention in the later tests. For the same reason the increase of stored energy would not account for the fact. Very little energy is required during the short test, and one is able to tap continuously, without decrease in rapidity, for several minutes, while here there was a rest of 15 seconds between each 5 second record and the succeeding one.\nThe experiments of Welch1 give results similar to those described above. She concludes that rhythm of the left hand affects the right hand for the pull of the dynamometer, but that after practice this influence disappears. The explanation of such facts is probably found in the development of lower automatic centers by practice. After this development two acts, each of which at first requires conscious attention, become easy of simultaneous performance because the new automatic centers control the movements independently of the mind.\nFig. 17 exhibits the fact that in the first day\u2019s practice the right hand taps about as rapidly whether tapping alone or in connection with the\n1 Welch, On the measurement of mental activity throtigh muscular activity and the determination of a constant of attention, Amer. Jour. Physiol., 1898 I 283.","page":44},{"file":"p0045.txt","language":"en","ocr_en":"Researches in cross-education.\n45-\nleft hand, while much of its speed is lost while tapping with either one or both feet. This means simply that one arm is in closer nervous connection with the other arm than the upper limbs are with the lower.\nVI. Theoretical.\nAn explanation of cross-education cannot as yet be completely and satisfactorily made. To aid in the explanation of the fact certain experiments of other observers are here brought together.\nExperments in diversion.\nLombard, 1 in his work with Mosso\u2019s ergograph, has shown that the strength of the right and left hands may vary either synchronously or independently. By means of two ergographs he secured records of both hands at the same time. He concludes that the variations are not due to any abatement of will power or attention, or to the fatigue of muscle ; but rather to changes which affect the lower centers of the spinal cord. The variations in strength which occur synchronously are due to changes,, probably circulatory, affecting large parts of the central system ; those-which occur independently are due to local changes.\nBryan\u2019s* 2 experiments in tapping, carried on with children of different ages, prove that the effects of effort, through either extremity, are shared by both ; and that the tapping ability of a joint is affected by the simultaneous exertion of the symmetrical joint on the other side.\nPatrizi3 found that the strength of one hand vari\u00e9s whether it works alone or with the other hand. In his tests with the ergograph he found : (1) that in simultaneous action, the right hand could do 3.67 kgm. of' work, and left, 2.94, total, 6.61 ; in alternative action, right, 3.72, left, 3.58, total, 7.30 (it should be noted that the gain in alternative action is made chiefly by the left hand, as if, in simultaneous action, more attention were paid to the right hand than to the left); (2) that with the left hand in isolated action, its work was 4.63 kgm.; and with the left working alternately with the right, its work was 5.64\u2014a gain of x.oi or 21.8%\u2014showing that the action of the right hand reinforces that of the left.\n'Lombard, Some alterations in the strength which occur during fatiguing voluntary muscular work, Jour, of Physiol., 1893 XIV 113.\n2 Bryan, On the development of voluntary motor ability, Amer. Jour. Psych. 1892-93 V 201.\n\"Patrizi, La simultan\u00e9it\u00e9 et la succession des impulsions voluntaires sym\u00e9triques, Archives Ital. de Biol., 1893 XIX 126, of which an abstract appears in the Ann\u00e9e-Psych., 1894 I 452.","page":45},{"file":"p0046.txt","language":"en","ocr_en":"\u202246\nWalter W. Davis,\nThe experiments of Welch,1 as well as my own already described in the section on Diversion of energy, reinforce these researches in establishing the very close nervous connection existing between the right and left limbs.\nExperiments on fatigue.\nIn Mosso\u2019s2 experiments with the ergograph, results appear to prove that muscular and central fatigue are quite distinct and independent. Fatigue, if considered as decrease in capacity for work,3 is due almost wholly to influences that are central. After complete volitional fatigue, the muscle may be made to do much more work by electrical stimulation \u2022either of the muscle itself or of the nerve leading to it. Lombard,4 and Rossbach and Harteneck5 6 support Mosso in these conclusion's.\nSuch considerations simplify the explanation of transference of practice; for if fatigue is chiefly central it is here that we must look for the most marked changes due to exercise. The effects of practice for the two hands, for example, are brought to an organ that has many things in \u25a0common for both members.\nObservations on attention and will power.\nToulouse 6 has proved the great importance of attention in acts of volition. The ability to pay attention decreases in all mental maladies. By means of the dynamometer he found that persons affected with diseases of the mind can exert only a feeble pressure, and he concludes that this inability is due to their lack of power to concentrate attention.\nStumpf,7 in commenting on the investigations of Fechner and Volk-mann, described above on pages 6 to 7, makes the development of attention of great importance in transference. \u201cThe capability of concentrating attention on a certain point in question, in whatever field it is acquired, will show itself efficacious in all others.\u201d Fechner, too, in this connection emphasizes attention.\n1\tWelch, On the measurement of mental activity through muscular activity and the detei mination of a constant of attention, Amer. Jour. Physiol., 1898 I 283.\n2\tMosso, Ueber die Gesetze der Erm\u00fcdung, Arch. f. Anat. u. Physiol., Physiol. Abth., J890 89.\n3\tScripture, The New Psychology, 228, London 1897.\n4\tLombard, The effect of fatigue on voluntary muscular contractions, Amer. Jour. Psych., 1890 III 24, also \u00c9ffet de la fatigue sur la contraction musculaire voluntaire, Arch. Ital, de Biol., 1890 II 380.\n5\tRossbach and Harteneck, Muskelversuche von Warmbl\u00fctern, Arch. f. d. ges. Physiol. (Pfl\u00fcger), 1881 XV 2.\n6\tToulouse, Notes sur quelques exp\u00e9riences dynamom\u00e8triques chez les ali\u00e9n\u00e9s, Soc. de ;Biol , 1893 V 121.\n7\tStumpf, Tonpsychologie, 1883 I 81.","page":46},{"file":"p0047.txt","language":"en","ocr_en":"Researches in cross-education.\n47\nGilbert and Fracker\u2019s recent investigations1 2 of reaction-time for sound prove that practice in reacting to one form of stimulus shortened the reaction-time for other forms. Like results were found for the ability of discrimination.\nScripture\u2019s2 hypothesis for explaining cross education is \u201cphysiologically speaking, that the development of the center governing a particular member causes at the same time the development of higher centers connected with groups of members. Psychologically speaking, development of will power in connection with any activity is accompanied by a development of will power as a whole. \u2019 \u2019\nObservations on mirror-writing.\nSaltmann,3 4 Piper* and Treitel5 have investigated the subject of mirror-writing, both in normal and abnormal persons and in children and adults. Their results show a greater tendency to reversed writing in the young and in those suffering with nervous disorders or sensory deficiency, notably in the blind, deaf and idiotic.\nGoldscheider,6 in his review of Saltmann\u2019s article, explains mirrorwriting as due to the greater influence in some persons of motor sensations over optical percepts. He considers that two directing factors must be distinguished in the production of writing ; the optical percept of the written sign and the motor sensations involved in the movements. In mirror-writing the motor sensations correspond to those in direct writing, but the written signs do not correspond to the optical percepts. The sequence of innervation occurs in this case under the influence of the motor sensations which appear to be dissolved from the optical percepts. These latter form the principal factor in general and with normal persons ; passing through the series of innervations according to motor sensations, represents a lower, partly mechanical type.\nGoldscheider\u2019s review apparently explains mirror-writing and also the transference of the effects of practice. If in certain persons the\n1 Gilbert AND Fracker, The effect of practice in reaction and discrimination for sound upon the time of reaction and discrimination for other forms of stimuli, Iowa Stud. Psych., 1897 I 62.\n2Scripture, Recent investigations in the Yale Laboratory, Psych. Rev., 1899 VI 165.\n3\tSaltmann, Schrift und Spiegelschrift b. gesunden ti kranken Kindern, Festschr. z. Henoch\u2019s 70. Geburtstag, 432, Berlin 1890.\n4\tPiper, Schriftproben von schwachsinnigen Kindern, Berlin 1893, reviewed in Zt. f.\nPsych, u. Physiol, d. Sinn., 1893 VI 74.\n6 Treitel, Ueber das Schreiben mit der Unken Hand und Schreibstdrungen, Deut, Zt. f. Nervenheilk., 1893 IV 277.\n6Goi.dscheider, Zt. f. Psych, u. Physiol, d. Sinn., 1891 II 414.","page":47},{"file":"p0048.txt","language":"en","ocr_en":"48\nWalter W. Davis,\nmotor sensations have a greater influence than the optical percepts, then by the transferrence of the motor sensations a movement is made on the other side that is symmetrical to the movement practiced. This symmetrical movement produces the writing in the reverse direction.\nReflex action.\nWalton 1 has shown the intimate connection between the centers of motion and sensation and between the motor centers for different groups of muscles. The muscles of a frog under the influence of strychnine may all be put into a condition of tetanus by the stimulation of only one point of the skin.\u2019 In ordinary reflex action the motor center for the muscle of the eyelid must be closely connected with the sensory center for the cornea, as the stimulation of one causes a contraction of the other.\nHofbauer 2 has proved by means of the ergograph that a stimulation of the sense of hearing may excite a muscle to greater action. A pistol shot at just the right moment causes a higher contraction than ordinarily ; but if it occurs a moment too soon or too late the contraction is hindered.\nObservations on the overflow of energy.\nThe researches of Exner 3 in reflex and cortical stimulation in the dog establish several important facts, (i) The two methods of stimulation may reinforce each other. ( i ) A cortical stimulation which concerns only the left foot reinforces the reflex act which, it might appear, concerns only the right foot and its central organ. That is, if the motor area for the left foot is stimulated electrically and at the same time the right foot is stimulated for reflex action, the movement produced in the right foot is greater than if only reflex stimulation is used. It was found, too, that cortical stimulation of the area governing one front foot reinfQrces reflex action in the hind feet, and likewise the reverse.\nUrbantschitsch,1 2 3 4 in his experience with pathological subjects with diseases of the eye and ear, has found true for the sensory nerves what Exner found for the motor nerves. Sensations, as well as motor impulses to action, may affect parts seemingly not immediately concerned.\n1\tWalton, Ueber Reflexbewegung dts Strychninfrosches, Arch. f. Anat. u. Physiol., Physiol. Abth., 1882 46.\n2\tHofbauer, Interferenz zwischen verschiedenen Impulsen im Centralnervensystem, Archiv f. d. ges. Physiol. (Pfl\u00fcger), 1898 LXVIII 546.\n3\tExner, Zur Kenntniss von der Wechselwirkung der Erregungen im Centralnerven-\nsystem, Archiv f. d. ges. Physiol. (Pfl\u00fcger), 1882 XXVIII 487.\t,\n4\tUrbantschitsch, Ueber den Einfluss von Trigeminus-Reizen auf die Sinnesempfindungen, insbesondere auf den Gesichtssinn, Archiv, f. d. ges. Physiol. (Pfl\u00fcger), 1883 XXX 129.","page":48},{"file":"p0049.txt","language":"en","ocr_en":"Researches in cross-education.\n49\nAn hour\u2019s exclusive operation on the right eye showed on the left a relative enhancement of the ability to see. In many patients with chronic catarrh of the middle car the observer was surprised to find that an important pathological influence was transferred from the ear to the sense of sight.\nDamsch1 explains the spreading of nervous impulses to action as due to the close connection of all motor centers. Impulses from the motor centers, tend to spread themselves by their entrance into the great central brain ganglion\u2014where fibers from all motor centers come together and are intimately connected. This spreading of impulses is hindered by a checking, or inhibiting, apparatus which keeps the impulse from going the wrong way. This apparatus is much improved by practice. In the young and in certain nervously disordered persons it is deficient.\nIt was noticed in the tapping experiment that there was a tendency at times for the subject\u2019s left foot to make movements to accompany those made by the right. Damsch\u2019s explanation for such movements is that the impulse sent to the right foot has in part escaped through the checking apparatus and gone the wrong way. In learning an act that involves fine coordination it is very obvious that the pupil executes many movements that are entirely unnecessary. The nervous impulse has flowed out into wrong channels. These observations show how closely related are the motor centers governing symmetrical or associated parts and how an influence sent out from the central nervous system to a peripheral organ, may be felt in other peripheral organs also.\nConclusions.\nThe following conclusions may be drawn from my own experiments and those of other observers.\na.\tThe effects of exercise may be transferred to a greater or less degree from the parts practiced to other parts of the body. This transfer ence is greatest to symmetrical and closely related parts.\nb.\tThere is a close connection between different parts of the muscular system through nervous means. This connection is closer between parts related in function or in position.\nc.\tWill power and attention are educated by physical training. When developed by any special act they are developed for all other acts.\nExplanation of cross-education.\nWith conclusions b and c established the explanation of transference is\n1 Damsch, Ueber Mitbewegungen in symmetrischen Muskeln an nicht-gel\u00e4hmten Gliedern, Zt. f. klin. Med., 1891 XIX 170.\n4","page":49},{"file":"p0050.txt","language":"en","ocr_en":"5\u00b0\nWalter W. Davis.\nprobably reached. There is no doubt that the most important effects of muscular practice are central rather than peripheral. The central effects maybe distinguished as:'(i) those dependent on the development of motor centers, that is, their improvement through exercise; (2) those dependent on the development of psychical factors, notably attention and will power. Of these two effects we would emphasize the first as the more important. In fact, in the tapping tests close attention and a strong will power were hindrances. In tests requiring strong effort these factors are useful.\nWith the improvement by exercise of the motor centers governing the right arm, there is through the close nervous connection an improvement also of the center governing the left arm. Besides this in tests where will power and attention are necessary, these elements are developed by the exercise of the right arm and are efficacious also for the left.\nThe peripheral effects of exercise cannot be ignored altogether. It has been noted before that in the dumbbell test, the left arm did no improve, relatively to the right, to so great a degree as it did in the other tests. It did not gain endurance to an extent comparable to the gain in the right. In purely muscular tests it is necessary not only to develop the center of motor control, but also to develop muscular tissue. The muscles must be put into better condition to gain endurance. It has been seen that the left arm gained in girth and to a varying extent in the power of endurance. This can be explained only by increased muscular nutrition.\nThe measurements to determine if the circulation varied alike in both arms when only one was exercised, gave negative results. That the centers governing the nutrition of the right and left arms are affected alike by the exercise of either arm, suggests itself as a probable reason for the increase in girth in the arm not used.","page":50}],"identifier":"lit28746","issued":"1898","language":"en","pages":"6-50","startpages":"6","title":"Researches in cross-education","type":"Journal Article","volume":"6"},"revision":0,"updated":"2022-01-31T12:57:49.197905+00:00"}