Tense and agreement in Moroccan Arabic agrammatism: Evidence for task effects

Abstract

ABSTRACT Background Cross-linguistic studies on agrammatism have provided evidence that tense inflection is severely impaired while agreement inflection is relatively preserved (Friedmann & Grodzinsky 1997, Benedet et al., 1998). More recent evidence has suggested that the tense deficit is central, affecting comprehension as well. To account for this pattern of performance, a number of hypotheses have been suggested, making different predictions about the nature of the tense deficit in agrammatism. Objectives The purpose of this study was (1) to examine the centrality of a tense-agreement dissociation in Moroccan Arabic agrammatism, and (2) to determine task effects on agrammatic performance. Methods We presented results from a picture description, two sentence completion and a grammaticality judgement task with five Moroccan Arabic-speaking agrammatic patients and five matched neurologically normal adults. Results Control participants performed at ceiling across all the experimental tasks used. PWAA revealed different patterns of performance. Findings from both picture description and sentence completion tasks indicated a dissociation between tense and agreement production, with tense being more error-prone than agreement. The tense-agreement dissociation found in production extended to the comprehension modality in the sense that patients were less sensitive to tense than to agreement violations. Findings indicated task effects on performance with patients performing differently across different experimental tasks. Conclusions Findings of the present study argue in disfavour of a structural or representational account of the tense deficit in agrammatism. The interaction between task effects and tense accuracy suggests that the deficit can best be characterized in processing terms, particularly being a manifestation of limited working memory capacity.