Data are presented from families of monozygotic twin pairs which give evidence of genetic variance on the Block Design Test, a nonverbal measure of intelligence. Analyses of genetic and environmental effects on behavior are possible with this kind of information. (SA)

Areas of agreement and disagreement concerning intellectual developmental and the problems of mental retardation espoused by the author and by Uzgiris are discussed in this paper. The importance of environmental factors, along with the genetic and/or constitutional nature of the organism on which these environmental events impinge, is seen as…

This issue of the IRCD Bulletin is devoted to commentaries on an article by Arthur R. Jensen on the nature-nurture controversy in a recent number of "Harvard Educational Review." Contents of the Bulletin are comprised of the following: "Education, Ethnicity, Genetics and Intelligence; Jensenism: Another Excuse for Failure to…

Much of our thinking about contemporary social problems reflects tacit presuppositions regarding the operation of heredity and environment in human behavior. These beliefs have important implications for practical decisions. Advances in genetics, psychology, anthropology, and other disciplines have contributed much to a clarification of the…