On subtypes of developmental dyslexia: Evidence from processing time and accuracy scores.

Determined the proportion of phonological dyslexics (Ph-DYS) and surface dyslexics (S-DYS) in a population of French dyslexics by applying A. Castles and M. Coltheart's (1993) regression method to 2 diagnostic measures: pseudo-word and irregular-word processing time. 31 dyslexics were matched to 19 average readers of the same age (aged 10 yrs, CA controls) and to 19 younger children of the same reading level (aged 8 yrs, RL controls). Compared to CA controls, there were more Ph-DYS than S-DYS. Compared to RL controls, there were still a high number of Ph-DYS. The reliability of these subtypes across different measures of phonological and orthographic skills was also examined. Compared to RL controls, both groups of dyslexics were found to be impaired only in phonological skills. The moment at which the 2 dissociated profiles emerged in the course of cognitive development was assessed by examining data that was collected when the children were 7 and 8 yrs old. The results show that only the S-DYS's orthographic deficit increased with development. The authors also looked at whether the Ph-DYS and S-DYS profiles were associated with other specific cognitive deficits. Specific deficits in phonemic awareness and in phonological short-term memory were found for both Ph-DYS and S-DYS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)