Among the many theories attempting to explain sex differences in spatial ability, one of the most highly researched is the X-linked recessive gene theory. This is a review of the major research done on that theory and shows the conflicting nature of the results. (Author)

In contrast to earlier notions, a systems view of an organism's development sees genes as only one component in a hierarchy of influences that produces finished traits and differentiation. Developmental canalization proceeds from genes, behavior, and environment as well as from the coaction of these factors. (BC)

The monograph reviews federal research activities and progress in biomedical and behavioral/social science research in mental retardation. Activities represent the National Institute of Child Health and Human Development and the Mental Retardation and Developmental Disabilities branch. The following categories are addressed in terms of biomedical…

Noting that beyond the individual variations among humans, there is a body of mental abilities common to every human being, this book examines the debate among researchers about the extent to which humans are "preprogrammed," and suggests a new scientific psychology of human development. By examining experimental data obtained from…