Page:Mind (Old Series) Volume 9.djvu/120

 108 G. STANLEY HALL AND E. M. HAKTWELL. exposed to the noise of a falling ball with warning, and five quickest reactions, by pressing the key, were made alternately with the right and with the left hand. From fifty to eighty reactions could thus be made without fatigue at one sitting, the records of which were read from the dials of the Hipp-chronoscope, and recorded and averaged. As a result of many hundred records, it was found that, for three of the four persons tested, the reaction- time 011 the stronger or preferred side was greater than that made by the non-preferred hand. This difference, though slight, was uniform and constant. The fourth student, right-handed, but not extremely so, made the quicker reactions, scarcely less uniformly and constantly, with the right hand. Should the rule which holds for the other three turn out to be a general one, we may have to reflect how the current view, that regards the left of the body and the right of the brain as predominantly passive, and the right side of the body and the left hemisphere as mediating more than half the motor functions, can be made to comport with Wundt's identification of apperception with the generation of the motor impulse. How, we should have to ask, upon his hypothesis, can the latter process be more rapid on the non-preferred side ? E. A dynamometer was designed, consisting of a stiff spring with two long inflexible arms, one of which carried a pencil and the other a broad metallic table for a piece of stiff paper, upon which the pencil recorded the degree of approximation of the two arms made by the hand of the experimenter. After each record the plate was slipped along a few millimetres for a new record by an assistant, who marked each line r. or 1., according to the hand used. The power put forth by the hand in clenching the spring is thus represented inversely by the recorded distance between the arms. This simple instrument, though by no means free from objection, we found sufficiently accurate in a long series of com- parative movements for our purposes. Our results upon the above four persons were as follows. I. The preferred hand can always exert the more force, showing that its pre-eminence is not in skill alone. This is the case in every series, averaged from eight or ten maximal clenches alternately with the right and left hand. There is sometimes, however, a sudden excess of power in the non- preferred hand. There is also, subordinate to the general effects of fatigue, very speedily and strongly manifest here, a change in the maximal power of both hands together, now slow, now abrupt. II. A maximal clenching movement with one hand is weakened if a like maximal movement be made at the same time with the other hand. This, which is the opposite of the result recorded by Quetelet, who found the power of each hand in- creased if the other was making the same effort at the same time, was uniform with the four individuals we tested. The pre- ferred hand had more power to interfere with and weaken or