Spatial deficit in familial left-handed children.

This study was designed to evaluate the hypothesis that familial left-handed children who presumably have bilateral representation of language ability should show an impairment in spatial ability. Children, whose average age was 8 yr. and of whom 22 were right-handed, 11 familial left-handed, and 11 non-familial left-handed, were tested on verbal subtests of the Wechsler Intelligence Scale for Children--Revised, i.e., Vocabulary and Similarities and on spatial subtests, i.e., Block Design and Object Assembly. The results did not support the hypothesis that the spatial ability of familial left-handed children would be worse than their verbal ability. However, there was modest support for the hypothesis that familial left-handers were worse in spatial ability than right-handers.