650 POPULAR SCIENCE MONTHLY. 



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 indi- 

 cates a well-balanced and hence a well-nourished brain, which in 

 turn is the essential requisite for well-balanced thinking and feel- 

 ing. 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, con- 

 nected thought, and give rise to more or less abnormal feelings. 

 It follows from these proj^ositions that the character of an indi- 

 vidual's movements is an index to his brain condition, and indi- 

 rectly 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 

 X^ierception through every sense are dulled, memory becomes halt- 

 ing 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 con- 

 trol of the body as a whole, and of the different parts, as the 

 hand, the tongue, etc.f He has also tested the elementary in- 

 tellectual processes according to methods devised by Dr. Joseph 

 Jastrow, wherein the ability to perceive and judge of form 



* For detailed results of some of the most important of these researches, together with 

 careful and complete descriptions in many cases of the methods of study employed, see the 

 following : Cowles, Neurasthenia and its Mental Symptoms ; Mercier, The Nervous Sys- 

 tem and the Mind; Donaldson, Growth of the Brain, pp. 27*7-323; Francis Galton, Jour- 

 nal of the Anthropological Institute, 1888, p. 153 ; Warner, Mental Faculty, p. 76 ; Dressier, 

 Fatigue, Pedagogical Seminary, June, 1896 ; Kraeplin, A Measure of Mental Capacity, Popu- 

 lar Science Monthly, vol. xlix, p. 756 ; Sinclair, Schoolroom Fatigue, Educational Founda- 

 tions, May and June, 1896 ; Bryan, The Development of Voluntary Motor Ability; Gilbert, 

 Studies upon School Children in New Haven, in Studies from the Yale Psychological 

 Laboratory, vol. ii. 



f It will not be possible here to give a description of the apparatus employed, with illus- 

 trations and details respecting methods of use, but the reader, if interested, can obtain com- 

 plete information relating to most of the apparatus by referring to Scripture, op. cit., as 

 follows: For the apparatus used in testing rapidity of thought and action, see pp. 27-37; 

 also pp. 43, 46, and 58. For the apparatus employed in testing the keenness of the senses, 

 see pp. 101-112; also pp. 124, 135, 139, 141, and 170-173. For that employed in deter- 

 mining physical control, see pp. 67-74, 79, 80, 86, 87. 



