Premium
Cognitive profiles of adult developmental dyslexics: theoretical implications
Author(s) -
Reid Agnieszka A.,
Szczerbinski Marcin,
IskierkaKasperek Ewa,
Hansen Peter
Publication year - 2007
Publication title -
dyslexia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.694
H-Index - 51
eISSN - 1099-0909
pISSN - 1076-9242
DOI - 10.1002/dys.321
Subject(s) - dyslexia , biological theories of dyslexia , psychology , cognitive psychology , cognition , phonological awareness , developmental psychology , developmental dyslexia , reading (process) , neuroscience , literacy , linguistics , pedagogy , philosophy
The aim of this study was to establish cognitive profiles of dyslexic adults on tests developed within the three main theories of developmental dyslexia: phonological, visual magnocellular and cerebellar and to investigate which theory can account for these profiles. The sample consisted of 15 Polish university students or alumni with a formal diagnosis of dyslexia, without ADHD and 15 controls matched on education, age, gender, IQ and handedness. The results revealed a striking heterogeneity of profiles. Nine dyslexics exhibited only a phonological deficit; one a phonological and a visual magnocellular deficit; a further three a phonological and a cerebellar deficit; two either a cerebellar or a visual magnocellular deficit. None of the three main theories of dyslexia can account for all the cases studied here. It is suggested that the best account of these data is in terms of different sub‐types of dyslexia with different underlying causes, such as phonological, visual magnocellular and cerebellar, or a combination of these. However, an account in terms of Ramus' (Trends, Neurosci. 2004; 27 (12):720–726) model, according to which the phonological deficit is a core deficit in dyslexia and other deficits (magnocellular and cerebellar), are just co‐morbid markers without a causal relationship to dyslexics' literacy difficulties, cannot currently be ruled out. Copyright © 2006 John Wiley & Sons, Ltd.