O'SHEA — ASPECTS OF MENTAL ECONOMY. 57 



mental application is as a consequence less perfect. Ill-adjust- 

 ment, disperseness, whether found in physical or mental action, 

 are due to the same causative agencies. Mental degeneracy be- 

 gets physical as well as psychical inco-ordination; imbecility is 

 characterized no less by lack of control and balance physically 

 than mentally. It seems as if we are able to say that on the 

 whole those who have the surest motor control have at the same 

 time superior possession of their mental powers. 1 



When it is remembered that fatigue dethrones attention, so to 

 speak, it is not difficult to see why it should so soon beget stu- 

 pidity, since a scattered mind cannot exhibit keenness, readi- 

 ness, or accuracy in any of its operations. We would expect in 

 the first place, that perception would be less discriminating, and 

 this has been demonstrated by extensive investigations upon the 

 several senses. 2 The writer has studied this subject in the 

 schools of Buffalo, H". Y., making use of simple experiments 

 which in a way tested the keenness and accuracy of interpreta- 

 tion of sense stimuli ; and he has found that two and one-half 

 hours' work in school lessens ability on the part of most pupils 

 to discriminate colors, as tested by sorting colored yarns, or 

 sounds as determined by the tone tester, or touch sensations as 

 determined bv the aesthesiometer, which Griesbach claims is the 

 best test for mental fatigue. 3 The data yielded by these studies 

 are in general in accord with those reached by such investigators 



iFor a summary of recent investigation relating to this subject, see Burk, 

 From. Fundamental to Accessory in the development of the Nervous System, 

 Pedagogical Seminary, vol. VI, No. 1, and Reprint. See also Oppenheim, The 

 Development of the Child, chaps. Ill, IV, V; Warner, The Study of Children, 

 chaps. Ill to XIII ; Donaldson, The Growth of the Brain, especially chap. XVIII ; 

 Halleck, Education of the Central Nervous System, chap. XI ; Mercier, The Nerv- 

 ous System and the Mind; Ross, Diseases of the Nervous System; Flechsig, Seele 

 und Gehirn, 1896; Hartwell Add. and Proc. N. E. A., 1893; Ireland, Blot on the 

 Brain, p. 257, et seq. 



2 See for the results of some investigations : Gilbert, Studies upon School 

 Children in New Haven, in Studies from the Yale Psychological Laboratory, vol. 

 II ; Sinclair, 'School-room Fatigue, Educational Foundations, May and June, 1896 ; 

 Dresslar, Fatigue, Journal of the Anthropological Institute, 1888. p. 153 et seq. ; 

 O'Shea, When Character Is Formed, Pop. Sci. Mo., Sept., 1897 ; also, Some Prac- 

 tical Phases of Mental Fatigue, Pop. Sci. Mo., August, 1899. 



3 Too much reliance, however, should not be placed upon the results of the 

 ffisthesiometric test. For myself I never could feel quite sure of my data. See 

 for a critical discussion of this method two articles by Leuba and Germann in 

 Psych. Rev., Nov., 1899. 



