Popular Science Monthly/Volume 56/March 1900/Cross-Education
DIRECTOR OF THE PSYCHOLOGICAL LABORATORY, YALE UNIVERSITY.
SOME years ago I made the following simple experiment: I arranged a rubber bulb, like that used for releasing a photographer's shutter, to connect with a bottle, from which rose a long, vertical glass tube. The bottle contained mercury, and the long tube reached nearly to the bottom. Every part was air-tight, so that when anybody squeezed the bulb the mercury was forced up the vertical tube. It was what is known as a mercury-dynamometer.
During experiments with this dynamometer, what was more natural than to think of trying what would happen if one hand were practiced daily in squeezing the bulb? So one of our graduate students. Miss E. M. Brown, was set to work in the following manner: On the first day she squeezed the bulb as hard as possible with the left hand, while an assistant noted the height of the mercury; this was repeated ten times, and the results were averaged. Immediately thereafter she took ten records with the right hand. Then, on the following days, with some intermissions, she practiced the right hand by squeezing ten times on each occasion. On the last day she again tested the left hand, which had not been practiced in the meantime. The records ran as follows:
|Left hand||29·6||. . . .||. . . .||. . . .||. . . .||. . . .||. . . .||. . . .||42·3|
Thus the left hand had gained about fifty per cent in strength through practice of the right hand. This peculiar phenomenon of transference of the effects of practice from one side to the other I have ventured to call "cross-education."
The phenomenon was curious enough to suggest other experiments. Another student. Miss T. L. Smith, was set to trying to insert the point of a needle at the end of a rod into a small hole in a drill-gauge without touching the sides. The first experiment consisted of twenty trials with the left hand, with a success of fifty per cent. Immediately thereafter twenty trials were made with the right hand, with a success of sixty per cent. On the following day and on each succeeding day two hundred experiments were made with the right hand, with successes of 61, 64, 65, 75, 74, 75, 82, 79, 78, and 88 per cent. On the last day the left hand, which had not been practiced in the meantime, was again tried, with a success of seventy-six per cent.
These last experiments remind us of certain familiar phenomena. It has frequently been noticed that persons taught to write with the right hand become able to write backward, but not forward, with the left hand. This is the so-called "mirror writing," which appears correct if seen in a mirror. The first published observation of this fact exists in a letter from H. F. Weber to Fechner, the founder of experimental psychology. Fechner, moreover, noticed that with the left hand he could make the figure 9 backward better than in the regular way.
Curiously enough, the principle of cross-education has been put to practical use. A letter (with permission to publish) has been received from Oscar Raif, Professor of Music i-n the Berlin Hochschule:
"In the spring of 1898 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 = 116 ( = 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 ; after two weeks, 126 ; three weeks, 132 , etc. After two months the right hand yielded 176 . Then I had them try the left hand, which averaged 152 , whereas in November the average was only 112 . In two months' time, absolutely without practice, the left hand had risen from 112  to 152 I 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.
"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 should 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 Fingerfertigkeit is the center of our nervous system—the brain."
These facts, however, require further investigation, for it is evident that we must begin with the fact of cross-education and proceed to more complicated cases. Indeed, cross-education has shown itself to be one step of a ladder up which we must climb even if there were no other motive except that of curiosity as to what we could find at the top. If practice of one hand educates the other hand, will it not also educate the foot? Again, if practice of one hand in squeezing a dynamometer develops the strength of the other members of the body, will it not also develop their dexterity or their advance? Again, if the development of voluntary power—let us say, frankly, "will power"—in one direction brings about a development in other directions, why should we limit the transference to muscular activity? Why can we not expect that the development should be extended to the higher forms of will power that go to make up character? The outlook begins to be stirring on account of its vastness. If the last principle be admitted, there seems no argument against the claim that some forms of manual training, such as lathe work and forge work, are just the things to develop moral character. By the same reasoning we would be obliged to admit the often-made argument that training in Latin, Greek, and mathematics furnishes a means of general mental development. If we admit the principle, we find ourselves at once involved in important educational controversies. However we may think in respect to these questions, it is plain that it is worth while to climb a ladder which has such an outlook at the top. Let us begin.
In the first place, the fact of cross-education is established. Let us ask in what this education consists. On this point some curious observations have been made by Prof. W. W. Davis, now of Iowa College. The subject of the experiment began by raising a five-pound dumb-bell by flexing the arm at the elbow; this called into play chiefly the biceps muscle for lifting and the forearm muscles for grasping. This was done as many times as possible with the right arm, and then, after a rest, with the left arm. The subject then entered upon a practice extending from two to four weeks; this consisted in lifting the weight with the right arm only. At the end both arms were tested as at the start.
The results were strange enough. The unpracticed left arm gained in power as we expected, but it also gained in size. Careful measurements were made by Dr. J. W. Seaver, of the Yale Gymnasium, on the girths of both upper arm and forearm. Let us compare the gains in girth with the gains in power:
|Subject.||GAINS IN GIRTH.||GAINS IN POWER.|
|Right biceps.||Left biceps.||Right arm.||Left arm.|
|G||5 mm||—5 mm||820 flexions||200 flexions|
We have arrived at the second step of the ladder, which is: The gain by practice which shows itself in cross-education consists in a development of higher nerve centers connected with the two sides
of the body. We must next ask: Is this effect of practice confined to the symmetrical organ, or does it extend to other organs? This question was answered by a peculiar experiment.
The experiment consisted in testing the effect of educating one of the feet to tap as rapidly as possible on a telegraph key. The apparatus is shown in Fig. 1. The clocklike instrument is really a piece of clockwork actuated by a magnet, so that it counts up one point every time the electric circuit is closed. The electric circuit is comprised of a battery and two keys. Any form of battery will do; the one in the figure is a "lamp battery"—that is, an arrangement of lamps in series and in shunt, such that the ordinary high-voltage city current is conveniently transformed into a low voltage current. The key to the left is the experimenter's key, and that to the right the subject's key. When the subject is set to tapping on the latter key the counter will register whenever the experimenter keeps his key closed.
For the actual experiments by Professor Davis the subject's key was removed to a distant room. Here there were three keys of this kind, any one of which would register. One key each was arranged for tapping with the big toes; the third key could be tapped by either right or left index finger.
On the first day all four digits—right and left index fingers and right and left large toes—were carefully tested in tapping as rapidly as possible. Thereafter the right large toe was practiced daily in tapping for several weeks, the other digits being left unpracticed. At the end all four digits were again tested. Four of the six persons experimented upon showed a gain for the right large toe—that is, for the digit practiced; the other two showed a slight loss, due unquestionably to "over-practice," or "over-training."
All of those who gained for the right large toe gained for the other digits also. Their average gains were: Right foot, thirty-three per cent; left foot, thirty-one per cent; right hand, twenty-one per cent; left hand, thirty-one per cent. Even both of the "over-trained" men gained for the left foot and one of them gained for the left hand. Thus we have reached the third step—the effects of practice are extended to various parts of the body.
Beyond the third step the experimental investigations have not yet advanced, but I believe that sooner or later we shall be able to establish the fact that development of those forms of the will involved in simple muscular activities does also develop the more complicated forms that express themselves in acts of a mental nature.
It has long been claimed that sports, games, and manual occupations are among the best developers of character. Football develops solidarity of feeling and action; running rapids or cross-country hunting develop coolness in danger and promptness and firmness of judgment; wood-turning requires boldness and foresight; forge work requires regulation and reserve of power, and so on. This is no place for an account of the psychology of sports and occupations, but if the reader has ever tried any of these things and failed he will easily recognize the lacking mental quality.
Yet there has never been but one attempt, as far as I can learn, to organize a system of manual occupations on the basis of this principle. The success of the attempt furnishes, I believe, the still-lacking laboratory proof of the principle itself. I refer to the remarkable experiment of Mr. Z. R. Brockway, Superintendent of the Elmira Reformatory.
Most of the young felons sent to the Elmira Reformatory are set to learning trades, by which they can support themselves on leaving. Those, however, who are too stupid to even learn the simplest trade are put into a manual-training school, in the hope that their brains can be sufficiently developed to enable them to keep out of the prison or the asylum. Those who are so stupid that they have difficulty in learning the alphabet or in counting their fingers are put into a kindergarten, where they practice on letter blocks and sticks and straws.
Those who are too stupid to learn a trade are the ones of interest here. Three main lines of defect are recognized in Superintendent Brockway's classification of them. Those who are intellectually weak, but of fair power of self-control, are classed as Group I; those who are reasonably bright, but are unable to get along because they can not control their impulses, are classed as Group II; those who fail on both sides are classed as Group III.
Group II is composed of those who are for the most part devoid of moral sense—those who fight, swear, assault officers, are licentious, and generally unresponsive to the usual reformatory measures. To this class belong some of the most intellectual inmates of the reformatory, but this intellectuality runs riot on account of weakness of character. How are their characters to be built up? They are required to devote most of their waking hours to athletics and calisthenics, wood-turning, making wooden patterns for castings, mechanical drawing, sloyd, clay modeling, and chipping and filing metal. These exercises have been selected on account of their character-building qualities.
The work is a great success. Nearly all inmates subjected to this building-up process finally graduate with sufficient self-control from the manual-training department into the trades school. A concrete example will give an idea of the change produced in the pupil. The record of No. 6,361 is instructive. The account is taken from a report by the manual-training instructor, R. C. Bates:
"The pupil, previous to his assignment to manual training, had earned for himself the sobriquet of 'dangerous man' among the officers and inmates. His offenses have been mostly threatening language, lying, contraband articles, talking, fooling, assaulting officers, and institutional crimes of that nature.
"We begin his record in September, 1895, when he was reduced to the second grade for fighting. October and November he lost three marks each for lying and threatening language, and, by the influence of September markings, caused his reduction to the third grade, or incorrigibles, a closely defined group. He was in the third grade two months and three days, when he was placed in the foundry, where, amid blinding smoke, stifling air, and the task system, it was thought he would tone down, upon the theory that the muscular demands of such a place on a 124-pound body would vitiate sufficiently to weaken the will and curb the disposition to riotous acts.
"From January 15th to February 15th he was on modified treatment. On February 18th he was unconditionally restored to the second grade. February and March he did fairly well, losing one mark each month, but in April his period of passably well-doing was checked by his committing an assault, along with assumption of authority, and on the 27th of April he was returned to the third grade for the second time, remaining in the same two months and three days, when he was again placed on modified treatment, and did well for three months, when he fell again, this time for fighting, losing six marks in October. In November he made a perfect month, securing promotion to second grade.
"On December 15, 1896, he was assigned to manual training, Group II; object, development of self-control, with subjects as follows: Athletics, drawing, sloyd, woodwork, chipping and filing, molding. Each subject one hour and a half per day, five days per week. The influence of the new environment sustained the effort made in November to improve, and, by securing a perfect month in December, all his past was blotted out and he was restored to the lower first grade again, through 'amnesty,' on December 25, 1896.
"Thus, on December 25, 1896, he was where he was institutionally classed at the time of his admittance two years and three months ago—viz., lower first grade, from which all who are committed begin the reformatory course of treatment, additionally thereto in the manual-training department. His development now begins. In January, 1897, he lost two marks as a result of school failures, but in February he secured a perfect demeanor record; in March he lost two marks; April and May were perfect months in all respects, and he was graduated from manual training in May, returned to institutional life, and assigned to the exercise squad in the morning and stone masonry in the afternoon. Later his daily assignment was changed, placing him in the molding class of the technological department to complete trade. His development was complete and permanent. He was returned to the manual training as assistant instructor in the molding class, and is now doing well in all departments, having been promoted to the upper first grade in August and ranking as sergeant in 'I' company."
This record is only one example of many.
When manual-training schools organize their courses on the principle of adapting the exercise to the ability to be developed, we shall have abundance of similar proof. When these facts have been incontestably established, there will be a means of satisfying the complaints of those who are constantly attacking our schools
- Studies from the Yale Psychological Laboratory, vol. vi.