Patterns of verb impairment in aphasia: An analysis of four cases

Aphasic patients often have difficulty producing and/or comprehending verbs. However, there has been relatively little research into what aspects of verbs are difficult for these patients. In this paper, we examine patterns of verb impairment in four aphasic patients who show different patterns of disruption. Of particular interest, one of the four patients shows preserved knowledge of semantic features of verbs and subcategorisation frames, but an inability to map this semantic information onto argument structure. This dissociation poses problems for psycholinguistic theories that would dispose of separate representations for subcategorisation frames and raises the issue of whether intact knowledge about subcategorisation frames is dependent upon intact semantic knowledge. Another patient appears to have a disruption in knowledge of the action specified by certain verbs. Such a disruption is intriguing because verb deficits have generally been assumed to result from the different grammatical role played by verbs relative to nouns. Our results suggest that not all verb deficits derive from the subcategorisation or thematic role complexity of verbs.