While, however, right-handedness is no mere acquired habit, but traceable to specific organic structure, the opinion has been already expressed that it is only in a limited number of cases that it is strongly manifested.
The conclusion I am led to, as the result of long observation, is that the preferential use of the right hand is natural and instinctive with some persons; that with a smaller number an equally strong impulse is felt prompting to the use of the left hand; but that with the great majority right-handedness is largely the result of education. If children are watched in the nursery, it will be found that the left hand is offered little less freely than the right. The nurse or mother is constantly transferring the spoon from the left to the right hand, correcting the defective courtesy of the proffered left hand, and in all ways superinducing right-handedness as a habit. But wherever the organic structure is well developed the instinctive preference manifests itself at a very early stage, and in the case either of decided right-handedness or left-handedness, it matures into a determinate law of action, which education may modify but cannot eradicate.
My colleague, Professor James Mark Baldwin, has followed up my own researches by instituting a systematic series of experiments on his infant daughter, extending over nearly the whole of her first year, with a view to ascertaining definitely the time at which the child begins to manifest any marked preference for either hand. As a specialist in the department of psycho-physics, he carried his inductive research beyond the range embraced in the present treatise; dealing with the question of feelings of efferent nervous discharge or innervation, the motor force of memories of effortless movement, and other conceptions of the psychologist which lie outside of the simpler issue under consideration here. Yet they naturally follow from it; for so soon as volition comes into conscious play, and the hand obeys the mind, and becomes an organ of the will, the psychical element is felt to dominate over the physical; including that very force of will which aims at eradicating the exceptional left-handedness, and enforcing an undeviating submission to the law of the majority.
It is unquestionably of first interest to the psychologist to inquire not only why the child, at the early stage in which a choice of hands is manifested, should prefer the right hand for all strong movements; but also, whether previous experiences in the use of both hands leave behind a sense that the nervous discharge which actuated the right hand was stronger than that which actuated the left. But the point aimed at here is to ascertain the originating physical initiative of determinate action, antecedent to all memory; the precursor of any such action stimulated by memory of an efferent current of discharge of nervous force. For that end the following results, derived from a careful series of observations on the voluntary actions of a healthy child throughout its first year, are of practical significance and value.
“(1) No trace of preference for either hand was found so long as there were no violent muscular exertions made (based on 2187 systematic experiments in cases of free movement of hands near the body: i.e. right hand 585 cases, left hand 568 cases: a difference of 17 cases; both hands 1034 cases; the difference of 17 cases being too slight to have meaning).
“(2) Under the same conditions, the tendency to use both hands together was about double the tendency to use either (seen from the number of cases of the use of both hands in the statistics given above), the period covered being from the child’s sixth to her tenth month inclusive.
“(3) A distinct preference for the right hand in violent efforts in reaching became noticeable in the seventh and eighth months. Experiments during the eighth month on this cue gave, in 80 cases, right hand 74 cases, left hand 5 cases, both hands 1 case. In many cases the left hand followed slowly upon the lead of the right. Under the stimulus of bright colours, from 86 cases, 84 were right-hand cases, and 2 left-hand. Right-handedness had accordingly developed under pressure of muscular effort.
“(4) Up to this time the child had not learned to stand or to creep; hence the development of one hand more than the other is not due to differences in weight between the two longitudinal halves of the body. As she had not learned to speak, or to utter articulate sounds with much distinctness, we may say also that right or left-handedness may develop while the motor speech centre is not yet functioning.”[9]
[9] Science, vol. xvi. pp. 247, 248.
But memory of prior experiences, habit confirmed by persistent usage, and the influence of example and education, all come into play at an early stage, and lend confirmation to the natural bias. The potency of such combined influences must largely affect the results in many cases where the difference in force between the two cerebral hemispheres is slight; and the stimulus to preferential action is consequently weak, as in many cases it undoubtedly is, and therefore not calculated to present any insurmountable resistance to counteracting or opposing influences. Under the term education, as a factor developing or counteracting the weak tendency towards either bias, must be included many habits superinduced not only by the example of the majority, but by their constructive appliances. So soon as the child is old enough to be affected by such influences, the fastening of its clothes, the handling of knife and spoon, and of other objects in daily use, help to confirm the habit, until the art of penmanship is mastered, and with this crowning accomplishment—except in cases of strongly marked bias in an opposite direction,—the left hand is relegated to its subordinate place as a supplementary organ, to be called into use when the privileged member finds occasion for its aid.