The relationship between right-handed children's assessed and familial handedness and lateral specialization.

Eighty right-handed males (6-12 yr of age) stratified into age x degree of handedness x family history of handedness groups were administered three dichotic (digit, syllable, environmental sound) tests. Older subjects accurately identified more stimuli than the younger subjects across tasks. There were significantly laterality differences for both verbal and nonverbal stimuli between family history of handedness groups regardless of the subjects' age and degree of handedness. Those subjects with familial sinistrality had attenuated right-side advantage for verbal and non-verbal stimuli and decreased nonverbal accuracy scores compared to the familial dextral subjects who evidenced at right-ear (left hemisphere) advantage for verbal stimuli and a left-ear (right hemisphere) advantage for nonverbal.