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Auteur: Zoltán BÁNRÉTI

Co-Auteur(s): Ildikó Hoffmann, Éva Mészáros, Márta Szücs

Recursion in language, theory-of-mind inference, and arithmetical calculations. Lessons drawn from Alzheimer's disease and agrammatic aphasia

Abstract/Résumé: The issue Some researchers claim that the human faculty of recursion is revealed by syntactic-structural embeddings, while some others claim it is due to recursive theory-of-mind (ToM) inferences or to pragmatic abilities. This study investigates how aphasic impairment and Alzheimer’s disease impinge on the human faculty of recursion. Tests and results Photographs were presented to Hungarian agrammatic aphasic subjects and questions were asked about the photographs:‘What might X in the picture be thinking of?’; etc. Broca’s aphasics gave answers containing (1) simple decriptive sentences (e.g., ‘X may be late’), (2) situative sentences (e.g., ‘Christ, I’ll be late!’). The latter expressed relevant ToM inferences. In this way Broca’s aphasics’ avoided using syntactic recursion. We administered the above tests to two Hungarian subjects with moderate Alzheimer’s disease (AD). They produced few and irrelevant simple situative sentences. On the other hand they produced grammatical 'that'-clauses. While syntactic recursion may remain unaffected in moderate AD, ToM inferences seem to be impaired. In the second-order false belief test moderate AD subjects gave the wrong answers. With respect to recursion in arithmetical calculations (cf. Varley at al 2005, Siegal-Varley at al 2006), we found serious limitation in the recursion of arithmetical operations in AD subjects. The agrammatic aphasics applied recursive arithmetical operations correctly. They used numerical symbols and operation signs that they were not necessarily able to verbalise. Conclusion In subjects with a moderate AD, syntactic recursion is unimpaired, as opposed to their limited ability to tackle ToM and arithmetical recursion. In agrammatic aphasics, we found limited syntactic recursion but normal ToM inferences and recursive arithmetical operations. On the basis of such dissociations we will argue for a theoretical model that posits a module of recursive operations in the human mind that is shared by linguistic, theory-of-mind, and arithmetical performance and can be selectively impaired. References Siegal, M. Varley, R., Want, S.C. 2006. Mind Over Grammar. Reasoning in Aphasia and Developmental Contexts . In: Antonietti, A., Liverta-Sempio, O., Marchettio, A. (eds): Theory of mind and language in developmental contexts, Springer, 107- 119 Varley, R. A., Klessinger, N. J. C., Romanowski, Ch. A. J. and Siegal, M. (2005) Agrammatic but numerate. Psychology PNAS Early Edition. The reserach was supported by the Hungarian National Research Fund (OTKA) No. 100804.