Treatment of semantic verb classes in aphasia: acquisition and generalization effects.

Verb retrieval difficulties are common in aphasia; however, few successful treatments have been documented (e.g. Conroy, P., Sage, K., & Lambon Ralph, M. A. (2006) . Towards theory-driven therapies for aphasic verb impairments: A review of current theory and practice. Aphasiology, 20, 1159-1185). This study investigated the efficacy of a novel verb retrieval treatment in two individuals with aphasia who experience verb retrieval difficulty. It involved training verb classes with large (e.g. cut verbs) and limited (e.g. contact verbs) sets of semantic features. Based on action representation theories, semantically based training of cut verbs was predicted to generalize to retrieval of untrained cut and contact verbs. One participant improved on trained verbs whereas the other participant did not. Neither participant demonstrated within nor across-class generalization to untrained verbs. However, both participants significantly improved in verb naming as measured by An Object and Action Naming Battery, and their predominant error pattern changed from noun to verb substitutions. Therefore, both participants improved in overall verb retrieval strategies despite limited success with verbs trained in this treatment. Implications for the design of future treatments are discussed.