SEX, BRAINS, HANDS, AND SPATIAL COGNITION

The literature that investigates the joint effects of sex, handedness, familial handedness, and spatial experience on the performance of spa tial tasks shows numerous significant interactions, but the results ar e difficult to interpret. Casey has proposed a model that incorporates the biological notion of a ''genetic right-shift factor'' and partici pation in visual-spatial activities to produce systematic differences in spatial performance. This model has many strengths including the sp ecific nature of its predictions that have been supported empirically across several different studies and the melding of biological propens ities and experience. However, many of the basic assumptions rest on s haky ground, and there is a body of contradictory evidence that still remains to be explained. (C) 1996 Academic Press, Inc.