Chinese morphological processing : an event-related potential study on developmental dyslexia using homophone verification task

Abstract

Children with dyslexia show persistent difficulties in reading. Contribution of morphological awareness to reading was widely examined in Chinese. Behavioral studies showed that children with dyslexia have poor morphological processing, but the underlying neurobiological contribution remains unclear. The present study aimed to understand the deviant morphological neural pattern and investigate the relationship of homophone sensitivity and reading. Event-related potential was used to compare homophone sensitivity under semantic congruency and orthographic similarity conditions among 14 dyslexic and 14 typically developing native Chinese Grade 4 children in a homophone verification task. Results showed a greater P200 under orthographically dissimilar condition in dyslexic group. Different topography and congruency difference pattern were observed in dyslexic and control group. At N400, both greater overall activation and orthographic similarity effect were observed in dyslexic group. Lateralization pattern observed in control was absent in dyslexic group. Furthermore, P200 and N400 components measuring homophone sensitivity of semantic congruency and orthographic similarity contributed significant variance in predicting reading ability. The present study suggested children with dyslexia show homophone processing deficits due to poor written form to meaning mapping and semantic integration. Morphological processing at behavioral and neural level may serve as a satisfactory tool in identifying poor readers.