Treatment of thematic mapping in sentence comprehension: implications for normal processing

Abstract

The inability of some aphasic patients to interpret semantically reversible sentences has been hypothesised to arise from failure to link the grammatical roles of nouns (e.g. subject, object) to their corresponding thematic roles (e.g. agent, patient). Several previous attempts to improve patients' thematic mapping abilities have demonstrated a range of treatment effects of considerable relevance to the development of cognitive models of sentence processing. This study reports a new treatment approach to thematic mapping impairment; it succeeded in improving auditory sentence comprehension in a chronic aphasic patient with a long-standing comprehension deficit. Generalisation of improvement to auditory comprehension of sentences with untreated verbs, to comprehension of written sentences, and to tests using pictorial and videotaped materials not used in treatment, place constraints on the range of possible interpretations of the functional locus of treatment effects. Two areas that did not show significant improvement following treatment included auditory comprehension of sentences lengthened with modifiers, and spoken production of active and passive sentences that express correct thematic roles. These null effects are also interpreted as providing information relevant to models of sentence processing, including the role of working memory in sentence comprehension and the nature of thematic mapping procedures in comprehension and production.