Semantic classification in aphasia: a study of basic, superordinate, and function relations.

Nonfluent and fluent aphasics were given classification tasks that required the aphasics to identify three kinds of relations: same basic level category, same superordinate level category, and same function. The subjects received the items in word and picture form. In addition the aphasics were required to name the items they were asked to classify. The results showed that the ability to classify is more disrupted in fluent aphasia than in nonfluent aphasia. Within fluent aphasia, the degree to which classification is disrupted is dependent upon the type of relation being tested. While the overall performance of the fluent aphasics was depressed in comparison to nonfluent aphasics, it was significantly more depressed on function relations. The ability to name an item had a significant effect on the ability to classify only for basic level items.