Left-handed and right-handed aphasics with left hemisphere lesions compared on nonverbal performance measures.

This study examined the performance of 21 left-handed (LH) and 57 right-handed (RH) aphasics with unilateral left hemisphere lesions on standardized measures of nonverbal ability, derived from the WAIS Performance Scale (Wechsler, 1958) and the Parietal Lobe Battery (Goodglass and Kaplan, 1972). The handedness groups were initially compared on a number of demographic, neurological, diagnostic, and language variables and found to be equivalent. When compared on measures of nonverbal ability, LHs were significantly more impaired than RHs particularly on tasks involving visuo-spatial organization and construction. This finding suggests that LH aphasics may have more left hemisphere representation than RH aphasics on some tasks for which the right hemisphere is typically dominant. Finally, this study provides some data to address the issue regarding the percentage of LHs relative to RHs who become aphasic from unilateral lesions. Out of 323 aphasics who were seen at the Aphasia Unit over a ten-year period, 43 (13%) were left-handed. Twenty-four percent of LHs, but only one percent of RHs, were aphasic due to lesions of the right hemisphere.