Ever decreasing circles: speech production in semantic dementia

Meteyard, L., Quain, E. and Patterson, K. (2014) Ever decreasing circles: speech production in semantic dementia. Cortex, 55. pp. 17-29. ISSN 0010-9452 doi: 10.1016/j.cortex.2013.02.013

Abstract/Summary

We explored the impact of a degraded semantic system on lexical, morphological and syntactic complexity in language production. We analysed transcripts from connected speech samples from eight patients with semantic dementia (SD) and eight age-matched healthy speakers. The frequency distributions of nouns and verbs were compared for hand-scored data and data extracted using text-analysis software. Lexical measures showed the predicted pattern for nouns and verbs in hand-scored data, and for nouns in software-extracted data, with fewer low frequency items in the speech of the patients relative to controls. The distribution of complex morpho-syntactic forms for the SD group showed a reduced range, with fewer constructions that required multiple auxiliaries and inflections. Finally, the distribution of syntactic constructions also differed between groups, with a pattern that reflects the patients’ characteristic anomia and constraints on morpho-syntactic complexity. The data are in line with previous findings of an absence of gross syntactic errors or violations in SD speech. Alterations in the distributions of morphology and syntax, however, support constraint satisfaction models of speech production in which there is no hard boundary between lexical retrieval and grammatical encoding.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/31376
Identification Number/DOI	10.1016/j.cortex.2013.02.013
Refereed	Yes
Divisions	Life Sciences > School of Psychology and Clinical Language Sciences > Department of Clinical Language Sciences
Uncontrolled Keywords	semantic dementia, speech production, frequency, morphology, syntax
Publisher	Elsevier
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