The Journal of Educational Psychology

When Yerkes in 1915 published his Point Scale Revision of the Binet Tests, he included among his findings data relating to the social and racial status of children tested. He concludes "that conditions which are in part describable as sociological are correlated with differences in intellectual performance, which may amount to as much as 30 per cent of the total." He says: "In view of this fact, which our results amply demonstrate, it is obviously unfair to judge by the same norm of intelligence two children, the one of whom comes from an excellent home and neighborhood and the other from a medium to poor home and neighborhood." This caution, so definitely stated by Yerkes, has by no means always been followed and the result is that conclusions, in many cases apparently unwarranted, or at least unproven, have been drawn in regard to the levels of intelligence of various social, economic and industrial groups. Even Yerkes himself has accepted the results of the Army Tests as definitely showing the fact that there are clear grades of intelligence among various occupational groups. He places at the top the professional group and at the bottom the unskilled laborer. While it is probable that this classification has some justification, it is evident