Effects of syntactic complexity, semantic reversibility, and explicitness on discourse comprehension in persons with aphasia and in healthy controls.

PURPOSE: Prior studies of discourse comprehension have concluded that the deficits of persons with aphasia (PWA) in syntactically based comprehension of sentences in isolation are not predictive of deficits in comprehension of sentences in discourse (Brookshire & Nicholas, 1984; Caplan & Evans, 1990). However, these studies used semantically constrained sentences in discourse, which do not require syntactic analysis to be understood. A discourse task was developed to assess the effect of syntactic complexity, among other factors, on discourse comprehension in PWA. METHOD: Thirty-eight PWA and 30 neurologically healthy control participants were presented with passages that contained 2-3 semantically reversible sentences that were either syntactically simple or syntactically complex. The passages were presented auditorily, and comprehension was assessed with the auditory and written presentation of 4 multiple-choice questions immediately following each passage. RESULTS: Passages with syntactically simple sentences were better understood than passages with syntactically complex sentences. Moreover, semantically constrained sentences were more likely to be accurately interpreted than semantically reversible sentences. Comprehension accuracy on our test correlated positively with comprehension accuracy on an existing test. CONCLUSION: The presence of semantically reversible, syntactically complex sentences in a passage affects comprehension of the passage in both PWA and neurologically healthy individuals.

Development of a theoretically based treatment for sentence comprehension deficits in individuals with aphasia.

PURPOSE: Two new treatments, 1 based on sentence to picture matching (SPM) and the other on object manipulation (OM), that train participants on the thematic roles of sentences using pictures or by manipulating objects were piloted. METHOD: Using a single-subject multiple-baseline design, sentence comprehension was trained on the affected sentence type in 1 task-related protocol in 15 participants with aphasia. The 2 tasks were SPM and OM; the treatment stimuli were object relatives, object clefts, passives, and unaccusatives, as well as two control structures-object relatives with a complex noun phrase (NP) and active sentences with three NPs. RESULTS: The criteria for efficacious treatment was an increase in the level of performance from the pretreatment probes to the posttreatment probes for the treated structure such that accuracy rose from at or below chance to above chance and either (a) accuracy rose by 33% or (b) the effect size was 2.6. Based on these criteria, the success rate for training the target structure was 2/6 participants in the SPM condition and 4/7 participants in the OM condition. CONCLUSION: The outcome of this study illustrates the utility of this theoretically motivated and efficacious treatment for sentence comprehension deficits in individuals with aphasia.