Comprehension of reversible active and passive sentences in agrammatism

Agrammatism is a language disorder characterised by a morphological and/or syntactic deficit in spontaneous speech. Such deficits are usually associat ed with comprehension disorders-though it is said that this is not always t he case-which result in a certain degree of variability in syntactic, lexic al, and morpholexical performance. The purpose of this study is to reconsid er the nature of comprehension disorders in agrammatism, to test whether Gr odzinsky's Trace Deletion Hypothesis (TDH) can be generalised to all agramm atic patients, and to ascertain whether the pattern of impairment observed in agrammatism differs from that present in fluent aphasic patients. Eleven agrammatic patients were tested by means of a sentence comprehension task comprising simple active and passive reversible sentences. The performance of the agrammatic patients was compared to that of 16 fluent aphasic (10 We rnicke's and 6 conduction) and 10 control subjects. The deficits observed in the agrammatic subjects were compatible with the T DH, but there was also impaired processing of pronouns (elements that are a lso subject to movement) and a mild deficit on the processing of simple act ive sentences. The fluent aphasic patients showed a similar pattern of impa irment. A logistic regression analysis was then applied to each single case separately, in order to study the homogeneity of the patients' performance within each aphasic subgroup. Of the 11 agrammatic patients, 3 did not sho w comprehension disorders, 5 had a specific deficit for passive movement, 1 a lexical deficit for pronouns only, and 1 a pattern of impairment compati ble with Linebarger et al.'s trade-off theory. The last patient showed a de ficit for simple active reversible sentences compatible with damage to the mapping of grammatical functions to thematic roles. Similar patterns of imp airment were also found in the fluent aphasic sample. Overall, the results lead to the conclusion that the TDH cannot be generalised to all agrammatic patients, that the mechanism it invokes is not the only source responsible for agrammatic comprehension disorders and also contributes to comprehensi on disorders in fluent aphasic patients.