The search for deep dyslexia in syllabic writing systems

Abstract

Current psycholinguistic models of the acquired dyslexias have largely been based on the ‘alphabetic writing systems’ and are in need of cross verification with data from readers of other kinds of ‘writing systems’. The study of the acquired dyslexias in the two languages of the bilingual/biliterate patient could provide valuable insights into the influence of the script as a factor particularly when the two languages/scripts differ in nature. This paper describes the reading deficits of a bilingual/biliterate patient in his native Hindi and in English. Like most of the other Indian writing systems, Hindi (Devanagiri) is phonologically transparent, nearly always regular, and can therefore be treated sub lexically. Use of the lexical route, although not prohibited, may not occur given that Hindi words, even the complex ones are phonologically transparent and there are very few irregular words. English, on the other hand, is a very irregular ‘alphabetic writing system’ and the lexical route is, consequently, very often required for both reading and writing. A.G., the patient reported here, while presenting with deep dyslexia in English had hardly any reading skills in his native language (Hindi). Given that the neural bases of sub lexical reading are impaired in deep dyslexia, the differential effect of this neural impairment on the processing of the two scripts is of interest for the validation of the psycholinguistic models and our understanding of the neural bases of reading.