Feature-processing deficits following brain injury. II. Classification learning, categorical decision making, and feature production

The claim that overselectivity in feature processing underlies the disorders that aphasics display in processing both visual and verbal material was directly tested by exploring the relationships between the behavior of brain-injured subjects on three experimental tasks: classification learning, categorical decision making, and feature production. From each of these tests a score selected as being indicative of overselective responding was entered into a principal components analysis, together with measures of visual recognition and memory, visual reasoning, naming skills, and severity of aphasia. This analysis supported the assumption that feature-processing disability is a specific and separable deficit, although related both to naming ability and to severity of aphasia. The relevance of the overselectivity hypothesis to naming difficulties following brain injury is discussed.