Sub-types of Dyslexia in different orthographies

The purpose of this project is to compare the underlying mechanisms involved in students with reading difficulties in alphabetic and logographic writing systems. Based on the dual-route model of reading, readers may use either the lexical (words are recognized as wholes) or sub-lexical (words are recognized through grapheme-phoneme correspondence) procedure to read. Castles & Coltheart (1993) and Jimenez (2000) provided evidence for the existence of these two mechanisms in English reading and Spanish reading respectively. They suggested that deficits in one and/or the other mechanism would lead to different patterns of reading disability. Surface dyslexia results from impairment of the lexical procedure with an intact phonological route to reading. Phonological dyslexia results from a highly selective deficit in the grapheme-phoneme transformation mechanism. It was found that surface and phonological dyslexic reading patterns were also found in the Chinese dyslexic readers. The ratio of surface to phonological dyslexia in Chinese orthography was similar to that of Spanish. A higher percentage of surface dyslexia was observed.