Page:Popular Science Monthly Volume 51.djvu/666

650 determine the effect of brain fatigue upon physical power and control and make inferences therefrom respecting thought and emotion, since there is little doubt that good physical control indicates a well-balanced and hence a well-nourished brain, which in turn is the essential requisite for well-balanced thinking and feeling. On the other hand, a lack of control in the body as a whole or special members thereof is indicative of an impaired state of the brain, and this impairment must interfere with vigorous, connected thought, and give rise to more or less abnormal feelings. It follows from these propositions that the character of an individual's movements is an index to his brain condition, and indirectly to his mental constitution, aptitudes, and possibilities.

As a result of considerable investigation of late, according to these various methods of study, it has been shown that, as might be expected, fatigue interferes in the first place with the keenness and integrity of one's intellectual processes. The power of continuous attention is lessened, the rapidity and accuracy of perception through every sense are dulled, memory becomes halting and uncertain, and reason grows illogical and erratic. The writer has studied during the past year the influence of brain fatigue upon school children in Buffalo by observations made during the regular work of the day, and by simple experiments with apparatus designed to test first, the rapidity of thought and action as determined by the length of reaction time upon stimuli presented to the different senses; second, the keenness and accuracy of sense perception; and, third, the power of control of the body as a whole, and of the different parts, as the hand, the tongue, etc. He has also tested the elementary intellectual processes according to methods devised by Dr. Joseph Jastrow, wherein the ability to perceive and judge of form