Further study of the X-linked recessive gene hypothesis for inheritance of spatial abilities.

Two measures of spatial ability were administered to 319 undergraduates, 93 parents, and 62 siblings. Although males outperformed females on both tests, the resulting correlational pattern did not conform to the trait pattern hypothesized on the basis of an X-linked recessive trait. Results from a pedigree analysis, however, were in the expected direction. The inclusion of pedigree analyses is urged in future research.