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Auteur: Vitor ZIMMERER

Co-Auteur(s): Ewa Dąbrowska, Rosemary A. Varley

Accounting for atypical profiles in aphasic agrammatism

Abstract/Résumé: Research into agrammatic comprehension in aphasia has described a pattern of impaired understanding of passives and retained ability on active constructions. The most prominent accounts of this dissociation (such as explanations based on syntactic movement or working memory) predict that patients who are unable to comprehend actives will also be impaired in the comprehension of passives. However, agrammatic profiles show great heterogeneity among patient samples (e.g., Caramazza, Capasso, Capitani, & Miceli, 2005). We report the case of a man with primary progressive aphasia (WR). Similar to a lesioned case reported by Druks and Marshall (1995), WR’s comprehension was at chance on active sentences, but at ceiling on passives. In a series of reversible sentence comprehension tests WR displayed difficulties with active transitives and truncated actives with an auxiliary. In passive sentences, he displayed sensitivity to the agent marker by, as well as the passive morphology of the verb. WR’s profile challenges current theories of agrammatism. We explore two explanations for this pattern of dissociation: 1) Comprehension of English passives relies heavily on processing morphological information, while comprehension of actives relies on configurational (sequential order) processing. Data from artificial grammar learning suggests that WR has difficulties with configurational information (see also Zimmerer, Cowell, & Varley, 2011; Zimmerer, Cowell, & Varley, under review). 2) Actives and passives differ not only in structure, but also in their semantic properties. We argue that loss of semantic control may impair processing of constructions with greater semantic diversity. We suggest that the construction grammar theories (e.g., Goldberg, 2006) can account for the range of agrammatic profiles. The framework describes constructions such as the active and passive as independent statements about surface form and meaning. Caramazza, A., Capasso, R., Capitani, E., & Miceli, G. (2005). Patterns of comprehension performance in agrammatic Broca's aphasia: A test of the Trace Deletion Hypothesis. Brain and Language, 94(1), 43-53. Druks, J., & Marshall, J. C. (1995). When passives are easier than actives: two case studies of aphasic comprehension. Cognition, 55, 311-331. Goldberg, A. E. (2006). Constructions at work: The nature of generalization in language. New York: Oxford University Press. Zimmerer, V., Cowell, P., & Varley, R. (2011). Individual behavior in learning of an artificial grammar. Memory & Cognition, 39(3), 491-501. Zimmerer, V., Cowell, P., & Varley, R. (under review). Artificial grammar learning in individuals with aphasia.