The study sought to use Jensen's two-level theory of mental abilities to predict some hitherto unknown or unnoticed phenomena--facts about which the theory should yield clear-cut predictions and which are not as clearly predictable from other theories, though they may receive ad hoc explanations after the fact. From the two-level theory of mental…

Discussed are the theoretical explanations of the observation that low intelligence quotient (IQ), low socioeconomic status children appear to be brighter in certain ways than low IQ middle class youngsters. The two different theories on IQ as a function of socioeconomic status--environmental or cultural vs. genetically determined biological…