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Talk;memory

Thursday stream 3 Session 14.00 - 15.40 Length 25 minutes

An investigation into the effects of Central Executive deficits on word recognition abilities of dyslexic teenagers

Sue Palmer

Centre for Human Communication and Deafness University of Manchester s.palmer@man.ac.uk

Abstract

This study investigated the development of the inhibitory function and the ability to switch retrieval plans in the Central Executive of working memory in relation to word recognition abilities of a group of dyslexic teenagers (mean age 14 years 1 month), their chronological age controls (mean age 14 years 1 month) and their reading age controls (mean age 9 years). Using a picture span methodology which manipulated similarity across phonological and visual dimensions, the group of dyslexic teenagers were found to exhibit both visual and phonological similarity effects, whereas both controls groups showed only effects of phonological similarity. In addition, perseveration errors on a Wisconsin Card Sort Task were found to be significantly higher in the group of dyslexic teenagers than in either control group. Phonological recoding in working memory involves not only accessing the phonological representation of the visual stimuli but also inhibiting any potentially confusing visual representation that may be activated. The fact that visual confusions are still present in children three to five years older than their reading age controls, in whom they are not found, suggests that incomplete development of the inhibitory mechanism, and the capacity to switch retrieval plans in the central executive may constitute a deficit and not just delayed development. Overall the results of this study suggest that one of the causes of dyslexia may be deficient development of certain functions of the central executive, which prevent efficient use of phonological recoding of visual/orthographic stimuli.