December 6, 1895.] 



SCIENCE. 



765 



It is sometimes said that the useful ap- 

 plications of the material sciences have 

 no parallel in the case of the mental sci- 

 ences, but I venture to maintain that psy- 

 chological experiments may have a high 

 degree of practical value. Thus, determi- 

 nations such as those here described are 

 useful in vai-ious ways. 



It would be of value to an individual 

 and to tliose having dealings with him if 

 he could be assigned a definite index of 

 precision. This could be determined early 

 in life, and the effects of environment and 

 methods of education could be determined. 

 It is generally acknowledged that chil- 

 dren should be treated as individuals and 

 not as bits of stone to be shaken together 

 until they became marbles, equally round. 

 We consequently need to study methods 

 which will discover individual differences 

 early in the life of the child. Education 

 may properly be devoted to overcoming de- 

 fects which would interfere with usefulness, 

 but perhaps its more important function is 

 to strengthen qualities which the individual 

 possesses and which may be developed so 

 as to serve his welfare and that of society. 

 From the point of view of science, private 

 benevolence aud State aid should be di- 

 rected less to supplying the ci-ipples with 

 crutches than to supplying the agile with 

 ladders. For this purpose it is evidently 

 important to devise tests which will demon- 

 strate natural aptitudes while the child 

 is very young. 



It is especially desirable to devise some 

 objective method to test the fitness of can- 

 didates for the civil service. Examinations 

 are of great importance in merely securing 

 some method of appointment other than 

 reward for personal or political services 

 rendered. But the form of examination 

 has often only an artificial connection with 

 the duties of the official. The story is 

 told that in answer to the question " what 

 is the distance of the moon from the earth?" 



the candidate replied that he did not 

 know, but that it was not so near that it 

 would interfere with his work in the post 

 office. It is, indeed, a fact that the man 

 who had independently observed (contrary 

 to the testimony of novelists) that the cres- 

 cent moon does not rise in the evening, or 

 (contrary to the testimony of poets) that 

 a baby does not reach for the moon, would 

 discover mental qualities of greater impor- 

 tance for most work than the man who re- 

 membered the number of miles from the 

 earth to the moon. Of course the accuracy 

 of observation would only be one of a num- 

 ber of tests which could be applied. The 

 candidate for post office clerk whose eye- 

 sight is good; who can accurately judge of 

 the weight of a letter; who can make many 

 similar movements in succession without 

 becoming fatigued; whose range of percep- 

 tion is large so that he can perceive at a 

 glance the address on an envelope; whose 

 reaction-time is short, so that he can 

 quickly distribute the letters, etc., would 

 probably be a more efficient public servant 

 than one who passed a slightly better ex- 

 amination in grammar and arithmetic. 

 Stress should be laid on the advantages of 

 obtaining quantitative results. In this case 

 the candidates can be arranged in order 

 without any chance of prejudice or mistake 

 on the part of the examiner. The report 

 would show that A has passed a better ex- 

 amination than B, and that the chances 

 are (say) nine to one that this result is 

 correct. 



As a last example of the usefulness of 

 measurements of the accuracy of observa- 

 tion and memory I maj^ refer to its appli- 

 cation in courts of justice. The probable 

 accuracy of a witness could be measured and 

 his testimony weighted accordingly. A 

 numerical correction could be introduced 

 for lapse of time, average lack of truthful- 

 ness, average effect of personal interest, 

 etc. The testimony could be collected in- 



