Interacting sex and familial sinistrality characteristics influence both language lateralization and spatial ability in right handers.

In 1981 McKeever and Hoff found a pattern of sex-familial sinistrality (FS)-visual field interaction on an Object Naming Latency Task. The FS - females and FS + males performed more symmetrically. Also in 1981, Hécaen, DeAgostini, and Monzon-Montes found a substantially lower incidence of aphasia following left hemisphere lesions in FS - females and FS + males. Both findings suggest a less strict left hemisphere dominance in FS - females and FS + males. We report a replication of the McKeever and Hoff findings and also evidence of a pattern of sex-FS interaction in spatial visualization ability wherein FS - females and FS + males perform better than FS + females and FS - males.