Performance Tests with Defectives

There is no need, in writing for this journal, to emphasise the service which the *Binet-Simon Scale for the Measurement of Intelligence and its many revisions have rendered in the study of mental deficiency. The substitution of objective measurement in diagnosis for mere personal opinion ; the possibility of estimating degrees of defect and of stating them in standardised language; the realisation that a condition of lowered intelligence does not as a rule improve with age; all these but rarely outline its benefits. And yet, perhaps because of the very vital importance of its services, we have at the present time great need to pause and consider lest in our use of the Binet Scale we attribute to it powers which it does not and cannot possess. For in dealing with the individual the apparent ease with which it estimates intelligence may prove our undoing. Mental ages and intelligence quotients may become magical formulae giving a spurious appearance of knowledge and leading to inferences entirely unjustified in fact and disastrous in application.