Orthographic and phonological processing in Chinese dyslexic children: an ERP study on sentence reading.

An event-related potential (ERP) experiment was conducted to explore the differences between Chinese-speaking dyslexic children and normal school children in orthographic and phonological processing during Chinese sentence reading. Participants were visually presented with sentences, word-by-word and were asked to judge whether the sentences were semantically acceptable. The crucial manipulation was on the sentence-final two-character compound words, which were either correct or incorrect. For the incorrect compounds, the second characters of the base words were replaced by homophonic or orthographically similar characters. It was found that, for the normal controls, the orthographic and phonological mismatches elicited more negative ERP responses, relative to the baseline, over a relatively long time course (including the time windows for P200 and N400) at the central-posterior scalp regions. In contrast, the dyslexic children in general showed no differences between experimental conditions for P200 and N400, although the more detailed time course analyses did reveal some weak effects for the N400 component between experimental conditions. In addition, the mean amplitude of N400 in the homophonic condition was less negative-going for the dyslexics than for the controls. These findings suggest that Chinese dyslexic children have deficits in processing orthographic and phonological information conveyed by characters and, compared with normal children, they rely more on phonological information to access lexical semantics in sentence reading.