BACKGROUND:Dyslexic children exhibit reading ability unmatched to age,although they possess normal intelligence and are well educated.OBJECTIVE:To examine the performance of dyslexic children in Chinese characters visual recognition tasks and to investigate the relationship between priming effect in character recognition and dyslexia.DESIGN,TIME AND SETTING:A case-control study was performed at the Department of Children and Adolescent Health and Matal Care,School of Public Health,Tongji Medical College,Huazhong University of Science and Technology between March and June 2007.PARTICIPANTS:A total of 75 primary school students in grades 3 and 5 were selected from two primary schools in Wuhan City,Hubei province,China,and were assigned to three groups.(1) Reading disability (RD,n=25);(2) chronological age (CA) group (n=25 normal readers that were intelligence quotient and age-matched to the RD group);(3) reading level (RL) group (n=25 normal readers that were intelligence quotient and RL-matched to the RD group).All children were right-handed and had normal or corrected-to-normal vision.METHODS:Recognition of target characters was performed in each child using a masked prime paradigm.Recognition speed and accuracy of graphic,phonological,and semantic characters were examined.Simultaneously,data,with respect to response time for each target character and error rate,were recorded to calculate facilitation values (unrelated RT-related RT).MAIN OUTCOME MEASURES:Response time,facilitation,and error rate in Chinese character recognition task were calculated.RESULTS:The baseline-adjusted facilitation of graphic,phonological,and semantic priming for dyslexic children was -0.010,-0.010,and 0.001,respectively.Dyslexic children displayed inhibition in graphic and phonological prime conditions.Facilitations under the three prime conditions were 0.026,0.026,and 0.022 for the CA group.In the RL group,results were 0.062,0.058,and 0.031 respectively.The differences of baseline-adjusted facilitation across the three groups were significant [F(2,216)=17.91,P<0.01],whereas the main effect of prime condition [F(2,216)=0.49,P>0.05]and the interaction of group (prime condition [F(4,216)=0.91,P>0.05]were not significant.The error rate under the three prime conditions was 0.066,0.077,and 0.079 for the RD group.As for the CA group,the results were 0.057,0.071,and 0.074 accordingly,and in the RL group,the results were 0.119,0.111,and 0.121,respectively.The difference of error rate across the three groups was significant (F=6.61,P=0.002).The error rate was significantly greater in the RL group,compared with the CA and RD groups,while no significant difference existed between the RD and CA groups.CONCLUSION:Dyslexic children were slower to recognize target characters than normal readers,and did not exhibit significant prime effects in graphic and phonological primer condition.These results suggested that dyslexic children exhibited general deficits in phonological and graphic processing,and presented a different patt in character recognition.These results could be interpreted by parallel-distributed processing models.