Are Americans becoming more or less alike? Trends in race, class, and ability differences in intelligence

Abstract

American students' test scores have been slowly but steadily declining for the past half century. Some recent explanations for this decline have focused on dysgenic trends resulting from low-IQ parents outbreeding high-IQ parents. In this article, the authors examined the evidence for dysgenic trends by considering race-, class-, and ability-related changes in intelligence test scores over time. They concluded that (a) racial differences in intelligence decreased from 1973 to 1988 and have remained fairly constant since, (b) intelligence differences between the upper and lower thirds of social class groups have been decreasing slightly since 1932, and (c) Preliminary Scholastic Assessment Test-score differences between the top and bottom quartiles have been relatively stable since 1961. Thus, the authors found no evidence supporting the dysgenic hypothesis. Rather, the combined evidence points to a growing convergence across racial, socioeconomic, and ability-related segments of American society. Copyright 1997 by the American Psychological Association, Inc.