THE MENTAL DIFFERENCES 
BETWEEN INDIVIDUALS. 
ADDRESS TO SECTION J (PSYCHOLOGY) BY 
Dr. CYRIL BURT, M.A., 
PRESIDENT OF THE SECTION. 
Tur most remarkable advances made by psychology during recent years 
consist in the rapid development of what threatens to become a new and 
separate branch of science, the study of individual differences in mind. 
Down to the close of the nineteenth century psychologists were all 
pure psychologists. They confined themselves, with an air of chaste 
aloofness, to the discussion of mind in general; they wrote and 
experimented solely on the abstract functions of consciousness as such. 
The varying eccentricities of minds in the concrete, how one man’s con- 
sciousness might be unlike another’s, were problems beneath their 
interest or beyond their ken. If, in some laboratory research, different 
persons gave dissimilar results, either in the sharpness of their senses 
or the speed of their reactions, the divergencies were treated as no more 
than unavoidable disturbances of measurement, vexatious errors to be 
eliminated by the method of averaging, not facts of special value to be 
éxamined in and for themselves. For the rest, the chief method of the 
psychologist was still introspection; and his chief subject, himself. 
Accordingly, although in this way he laid the necessary foundations of 
a sound terminology and a safe technique, he nevertheless exposed him- 
self to the taunts of his literary colleagues, who knew that it takes all 
sorts to make a world. ‘ Les philosophes ’ (laughs an early and un- 
orthodox observer) ‘ sont toujours trop oceupés a eux-mémes pour avoir 
le loisir de pénétrer ou de discerner les autres.’ 
Of late, however, a body of workers has arisen who have turned 
their attention more especially to the peculiarities of particular minds. 
The variations have attracted them more than the averages; and the 
-mental disparities between childhood and age, between race and race, 
_ between one sex and the other, and between each unique individual and 
the rest, have formed their chosen topic. As a result of their labours, 
there has grown up, step by step, a vast and miscellaneous accumulation 
of data which urgently demands to be sifted and systematised. The 
practical needs of applied psychology, in each of its fresh spheres—the 
psychology of war, of education, of industry, of mental disorder, defi- 
ciency and crime—all depend for their solution upon a sound doctrine of 
st individual differences; and their study in its turn has already contri- 
buted much welcome information to the parent science. I propose, within 
1 La Bruyére, Les Caractéres (1687). 
