The role of individual difference in determining the nature of comprehension defects in aphasia.

This study was concerned with the relationship between locus of lesion and subtypes of language comprehension defect in aphasia. Previous studies had indicated that performance in sound recognition identified two subtypes of aural comprehension deficit and that performance in pantomime recognition identified two subtypes of reading comprehension defect. Defects in sound recognition and pantomime recognition were found in association with a variety of lesion loci. However, comprehension defective aphasics with normal sound recognition or pantomime recognition had lesions closely similar in location and size to those of aphasics who performed poorly on these tests. Findings suggest that whether an aphasic with a language comprehension defect is impaired in sound recognition or pantomime recognition depends, at least in part, on individually variable predisposing factors. It would appear possible that this phenomenon reflects a separate dimension of hemispheric cerebral dominance.