FAMILIAL HANDEDNESS AND LEFT-RIGHT DIFFERENCES IN AUDITORY AND VISUAL PERCEPTION

Dichotic listening and tachistoscopic recognition tasks were administered to 20 right-handers and 20 left-handers. Within the left-handed group, 10 subjects had a familial history of left-handedness and 10 did not. One tachistoscopic procedure was analogous to dichotic listening in that different letters were presented simultaneously, one to each field. A second visual procedure involved the presentation of single letters randomly to the left or right of fixation. Right-handed and non-familial left-handed subjects showed a right-side superiority on all tasks, while the familial left-handers tended to identify material presented to the left side more accurately. Correlations between the tasks indicate a dissociation of laterality effects in auditory and visual modalities. The results suggest that cerebral dominance is indeterminate only in familial left-handers. © 1969.