Phonological or procedural dyslexia: Specific deficit of complex grapheme-to-phoneme conversion

Phonological dyslexia is a written language disorder characterized by poor reading of nonwords when compared with relatively preserved ability in reading real words. There are two main theoretical proposals to explain this deficit: disruption of phonological processing or disruption to the nonlexical reading route affecting the grapheme-to-phoneme conversion rules (GPC). In this study, we report a single-case study of a mild aphasic patient with acquired phonological dyslexia. His ability was unimpaired for reading words, as well as in a wide range of tasks requiring the activation and explicit manipulation of phonological representations. He could also read every nonword with consistent GPC rules, whilst he was impaired for those with context-sensitive conversion rules, a pattern of performance never reported before. The implications of these results for theoretical explanations of phonological dyslexia are discussed, as well as the contribution of the patient’s concomitant executive deficits to his performance in reading.

► We explore the functional origin of phonological dyslexia in a patient with aphasia.
►  The patient showed no phonological impairment.
► He was impaired for nonwords with context-sensitive GPC rules.
► His reading deficit exclusively affects the nonlexical reading route.
►  This pattern of performance directly challenges current theoretical models of reading.