50 PSYCHOLOGICAL METHODS OF TESTING INTELLIGENCE 



(c) Children of different social strata. Social 

 differences turn out otherwise than do differences 

 of nationality, for they come out more or less con- 

 spicuously in the results of the tests. The task of 

 making comparative investigations by the graded 

 tests of children of different social levels was under- 

 taken in 1910 by Binet (36, p. 187) and by Breslau 

 teachers, simultaneously. 



The incentive that led Binet to undertake this 

 problem arose in certain investigations conducted 

 by Decroly and Mile. Degand in a private school at 

 Brussels (45), the results of which seemed to cast a 

 measure of doubt upon the value of Binet 's tests, 

 since the tests turned out, all of them, to be too easy. 

 To be explicit, of 45 children tested, no one was be- 

 low, 9 were at, and the rest were above the level of 

 their age (13 by one year, 17 by two years, and 9 

 even by three years). 10 Binet now points out, and 

 rightly, that these figures present no argument what- 

 soever against the value of his tests, but merely af- 

 ford a positive contribution to the study of the dif- 

 ferentiation conditioned by social factors. For all 

 these Belgian children were sprung from the circles 

 of the cultured middle class, whereas the Parisian 

 children to whom the tests were ' fitted' belonged 

 to lower classes. Binet, on this basis, reckons the 

 average difference in mental age between children 

 of the higher and lower classes at approximately a 

 year and a half. Of course, this figure can stand 

 only as a rough approximation ; it will vary, partic- 

 ularly at different levels of chronological age a 



10 See the review by Bobertag, Zeits. f. angew. Psych., 5 : p. 205, 



