Identified subjects' handedness and family handedness (genetic variables) and college major (environmental variable); and tested subjects on the Vandenberg Mental Rotation Test. Found that right-handed females with non-right-handed relatives and with science or math majors outperformed other females and equaled the performance of males on the…

Notes Halpern's general support for Casey's model. Addresses differences in Casey's and McKeever's findings on familial handedness and females' spatial ability by performing another experiment in which data are analyzed according to two different theoretical assumptions. Addresses the question of the heritability of handedness by noting that what…

Examined ability of individuals biologically predisposed to poor spatial skills to capitalize on opportunities to develop these skills. Found that for girls with brothers, those from all right-handed families had lower mental-rotation scores than did others. Among children participating in mental-rotation-type activities with their brothers,…