Feature-processing deficits following brain injury. I. Overselectivity in recognition memory for compound stimuli.

A previous experiment (S. Wayland & J.E. Taplin, 1982, Brain and Language, 16, 87-108) demonstrated that aphasic subjects had particular difficulty performing a categorization task, which for normals involves abstraction of a prototype from a set of patterns and sorting of other patterns with reference to this prototype. This study extended the investigation to a recognition memory task similarly organized in categorical structure. The aim was to replicate the previous findings and to delineate the precise nature of aphasics' difficulties with such tasks. Aphasics were again found to be aberrant in performing this task in comparison with normal subjects, nonaphasic brain-injured control subjects also demonstrating a departure from normality. The results suggest that the problem for brain-injured subjects is one of overselectivity in terms of the features of the stimuli to which they respond rather than a difficulty with prototype abstraction itself.