Abstract: The phonological processing deficit is the major cognitive impairment of developmental dyslexia in alphabetic countries. Some researchers have suggested that there are different subtypes in dyslexia, such as surface or delayed dyslexia and dyslexia with rapid naming deficit. Chinese characters belong to ideogram, with one character usually denoting one morpheme; they do not bear a grapheme-phoneme correspondence. An important question for developmental researchers is what the dominating cognitive deficit is in Chinese developmental dyslexia. Researchers in Hong Kong found that the rapid naming deficit and orthographical skills deficit were the primary cognitive deficits, and that there was lower incidence with phonological deficit. However, researchers in Beijing found that Chinese developmental dyslexics mainly possessed morphological awareness deficit. One possible cause of the inconsistency was that the analysis of subtypes in the studies was based on chronological-age controls, which might make the direction of causality unclear between some cognitive deficits and dyslexia because the cognitive skills and reading abilities usually contained interactive relations. In the present study, we intended to further examine the subtypes of Chinese developmental dyslexia, in order to clarify the cognitive deficit profile in Chinese dyslexia.
According to the low achievement definition, we selected 29 dyslexics from 654 children aged 9~12.8 years, and comparison groups with appropriate chronological-age (26) and reading-levels (28). Five reading-related cognitive skills were examined, including phonological awareness, rapid automatic naming, morphological awareness, orthographic skills and homophone choice task. Adopting one standard deviation cutoff criterion for every variable based on scores of reading-level controls, we explored the cognitive deficit profile of 29 Chinese developmental dyslexics. Finally Chinese character recognition test was administered in order to investigate whether the children’s error pattern and regularity and frequency effect were distinct in different subtypes while reading characters.
The main results are as follows.
1. There were different subtypes in Chinese developmental dyslexia, mainly including phonological dyslexia, dyslexia with rapid naming deficit, and dyslexia with double deficits of phonological awareness and rapid naming skills. A small proportion of dyslexics displayed orthographic-skill deficit. Finally, about one quarter of the dyslexics showed no severe cognitive deficits.
2. The dyslexics with phonological deficit exhibited more semantic errors while reading Chinese characters and were less able to detect the partial phonological information of the phonetic-radical in semantic-phonetic compounds.
3. The regularity-frequency effect patterns of children with rapid naming deficit were similar to those of the reading-level controls and revealed a general delay of reading development. They tended to recognize characters by the phonetic-radical.
4. The dyslexics with double or multiple cognitive deficits manifested the most severe reading impairment.
The results indicate that the cognitive deficit profiles of Chinese developmental dyslexia were consistent with the-double-deficit hypothesis of English developmental dyslexia, illustrating a cross-character consistency. Furthermore, the interaction among the reading-related cognitive skills likely determined the severity of dyslexia. The findings have implications for the diagnosis and intervention of Chinese developmental dyslexia. However the origin of phonological and rapid naming deficit needs to be investigated

Key words: developmental dyslexia, subtypes, the phonological deficit, the rapid naming deficit, Chinese character recognition