GENERALISED TREATMENT EFFECTS AFTER REHABILITATION IN PATIENTS WITH NEUROPSYCHOLOGICAL DEFICITS: THE ROLE OF COGNITIVE MODELS. by

An impairment in generating regular relative to irregular past tense verbs has been noted in nonfluent aphasia. Dual mechanism accounts attribute this deficit to an impaired rule-based route responsible for stem affix (‘play’ + ‘ed’) operations, and spared retrieval of past tenses from lexical knowledge. In contrast, single mechanism accounts suggest that the dissociation reflects an impairment in the phonological representation of verb forms. A rehabilitation study was reported, targeted at improving the production of past tense verbs and nonlinear sentences in a nonfluent aphasic patient (DS). The study used a thematic mapping procedure requiring DS first to describe what was happening in a picture with two characters, and then describe the events again but starting with the other character. Two thematic questions followed and DS was asked to produce the linear and non-linear sentences again. Generalised improvements were seen in the production of non-linear sentences and in producing treated and untreated regular past tense verbs. Interestingly, the improvement on treated irregular verbs generalised only to untreated irregulars from the same neighbourhood groups as treated words. The findings support an account positing generalisation based on lexical neighbourhoods.