']6 foiinial of Comparative Neurology and PsyeJiology. 



lines of investigation are necessary, and they should not conflict, but 

 should supplement each other. But as to the problem of the appear- 

 ance of consciousness in the world, we must continue to say : h^^no- 

 rabiinus. J. carleton bell. 



The Measurement of Mental Traits.' 



Those interested in the scientific study of education will welcome 

 this book as a contribution to its methods. Professor Thorndike, fol- 

 lowing the line of Galton's famous researches, undertakes to bring 

 together in a brief space such of the reliable statistical methods as have 

 already proved fruitful or promise fruitful results in the study of men- 

 tal traits, especially of school children and college students. Per- 

 haps the greatest value of the book, as the author himself foresees, 

 will be to bring home to educators, more forcibly than heretofore, the 

 untrustworthy character of the current generalizations on education, and 

 to create a demand for inductive statistical study of the facts, such as 

 those being carried on by Professor Cattell, himself, and others, in our^ 

 own country. 



The implied assumption underlying the whole treatment in this 

 book is that of the possibility of mental measurement This does not 

 mean an attempt to measure that timeless and spaceless, that incom- 

 mensurable, abstraction that often goes by the name of the "mental" 

 in discussions of the mind-matter problem. It means measurement of 

 the behavior of an organism in terms of those reactions which have 

 come to be called mental because of their relations to the so-called 

 higher values in life — but essentially identical in principle with physi- 

 cal or medical measurements. It is in this sense, apparently, that the 

 author seeks "units of mental measurement" (p. 169), comparable to 

 the inch, the ounce, the ohm, the ampere, the calorie, etc., in physical 

 science. The difficulty is a practical one only. There is no inherent 

 theoretical reason why such a unit may not be found and used. The 

 variability of mental traits renders measurements approximate only. 

 But this is true ultimately of all measurements ; they are all anthropic 

 at first. And approximate accuracy is better than the vagaries of cur- 

 rent theory, while "the greater the number of measurements, the closer 

 the approximation will be." 



If education is to become a science, the physical and mental meas- 



' E. L. Thornuike, Educational Psychology (Library of Psychology and 

 Scientihc Methods, edited by J. McKeen Cattei.I,). Neiv York. Lemcke and 

 Biuhner, 1903. 



