Are acquired dyslexias and dysgraphias language: specific or universal?

The aim of the current paper is to provide a review of the neuropsychology of acquired reading and writing impairments from an orthographic transparency perspective within the dual-route framework. Orthographic transparency refers to the ease with which one can directly predict phonology (sound) from orthography (print) in a given alphabetic writing system. Writing systems with highly predictable mappings between print and sound are said to be transparent (e.g. Turkish, Italian, Spanish) whilst unpredictable mappings between print and sound lead to opaque writing systems (e.g. English, French, Arabic). In addition, in some orthographies (such as Persian) transparent and opaque words coexist in print. The impact of orthographic transparency on normal (and impaired) language processing has led to the development of at least two opposing views, namely the orthographic depth hypothesis and the universal hypothesis. Ultimately the objective here is to demonstrate how neurological damage to the language area in the brain is linked to acquired dyslexia and dysgraphia irrespective of orthographic transparency. That is, neurological damage to the brain yields impairments that are universal in nature but perhaps manifested in a different way depending on the specific characteristics of the language. Evidence from atypically transparent Turkish orthography will be utilised to argue in favour of the universal hypothesis.

Also published in Contemporary Psychology, (ISSN: 0010-7549.) Fall, 2006 Vol 1 no 2. p.18-24.