Purpose: This study was designed to examine the hypothesis that discourse task types influence language performance in Mandarin Chinese-speaking people and to reveal the discourse task-specific linguistic properties of persons with anomic aphasia compared to neurotypical controls.
Method: Language samples from persons with aphasia (n = 31) and age- and education-matched controls (n = 31) across four discourse tasks (sequential-picture description, single-picture description, story narrative, and procedural discourse) were collected from Mandarin AphasiaBank. Task-specific distributions of parts of speech were analyzed using mosaic plots. The main effects of tasks in each group and the between-group differences within each task for several typical linguistic variables were evaluated, including the mean length of utterance, tokens, moving-average type-token ratio, words per minute, propositional density, noun-verb ratio, noun percentage, and verb percentage.
Results: The results revealed an impact of discourse tasks on most language variables in both groups. In the healthy controls, story narratives yielded the highest total words and lowest verb percentage. In the aphasia group, procedural discourse elicited the fewest total words and densest expressions, whereas their single-picture descriptions had the highest noun-verb ratio. For all tasks, the aphasia group performed worse than the control group in the mean length of utterance, tokens, moving-average type-token ratio, and words per minute. For noun-verb ratio, noun percentage, and verb percentage, only one task (i.e., single-picture description) showed significant between-group differences.
Conclusion: The selection of discourse tasks should be addressed in assessments and interventions for Mandarin Chinese-speaking individuals with aphasia to obtain more accurate and feasible outcomes.