Spatial lateralization: the relationship among sex, handedness and familial sinistrality.

Spatial lateralization was examined in 80 subjects by use of a strictly balanced design contrasting sex, handedness and familial sinistrality (absent and present). A modified version of Witelson's dichaptic stimulation task (verbal and nonverbal) was employed. The verbal task showed a significant main effect for the right-hand score. On the nonverbal task only two groups displayed a significant difference between hand scores: left-handed males with familial sinistrality and right-handed females with no familial sinistrality. Results are discussed in relation to previously reported data.