One hundred eighty one sets of black twins and 223 sets of white twins provided responses to four 12-item subtests of the Raven's Progressive Matrices Test, Standard Version. The children were in elementary school and their item response patterns were analyzed with the use of revised ordering-theoretic methods to search for best-fitting…

This book is organized in nine parts, as follows. Part I, "Preface," includes an account of how the author went from the rather esoteric research on theoretical problems in serial rote learning to research on the inheritance of mental abilities and its implications for education. Part II, "How Much Can We Boost IQ and Scholastic Achievement?," is…

Swedish longitudinal studies of twins support Scarr-Salapatek's explanation of nature-nurture influences on intelligence. This model predicts more genetic variance in test results for advantaged than disadvantaged groups. Jensen's work, however, suggests equal amounts of variance among different social classes. (Author/CP)