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…

Identifies three main strengths of Casey's spatial ability model, but notes that a study by McKeever found different results concerning the relationship between familial handedness and females' mental rotation ability. Considers the use of a familial handedness measure to be a weakness of the model because handedness might not be an inherited…

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…