The effects of task variation on the production of grammatical morphology in Broca's aphasia: a multiple case study

Generally task variation is not taken into account in discussions about agrammatism in Broca's aphasia. Both free speech and speech under constrained conditions are classified as "agrammatic speech." In this study, we investigated the effects of task variation on the character of agrammatic speech. We employed three types of task situations, an interview and two picture description tasks, to elicit speech from 16 Dutch and 3 German Broca's aphasics. The two picture description tasks differed in the extent to which they necessitated the production of grammatical morphology. Various task-dependent changes in the character of agrammatic speech were observed. Overall, omission rates of grammatical morphemes went down and substitution rates tended to go up in picture description as compared to free conversation. Results are discussed by contrasting two explanatory concepts, task interaction and strategic variation.