| Developmental dyslexia(DD)is generally regarded as a specific reading difficulty across different languages.While there are no obvious brain damage,mental disorder or visual impairments,dyslexics showed lower reading level when comparing to their chronological age controls despite normal intelligence level and access to normal school education.Studies have shown that dyslexics performed worse in RAN(rapid automatized naming)tasks than controls,indicating a RAN deficit in dyslexics.There are two hypothesis accounting for the reason why dyslexics showed RAN deficits:some researchers thought dyslexics showed reduced parafoveal preview benefits,while others thought dyslexics showed increased parafoveal load costs than normal controls.Silva et al.(2016)used a modified RAN paradigm in adult dyslexics and controls,by manipulating parafoveal preview and load independently they got parafoveal preview benefits and parafoveal load costs directly,by contrast between groups,the results was in support of the hypothesis that dyslexics showed reduced parafoveal preview benefits than controls.Based on this new paradigm,the current study went further to understand the role parafoveal processing played in dyslexics who showed RAN deficits.There are two experiments in this study.In experiment 1,we investigated characteristics and differences of parafoveal processing in Chinese children with developmental dyslexia(DD),chronological age control(CA)and reading level control(RL).Participants were screened from 3-5th grade in two primary schools in Tianjin,we had 12 children in each group.We adopted a 3(subject group:DD,RL,CA)× 2(parafoveal preview:preview,no preview)×2(parafoveal load:load,no load)mixed experiment design.Following the modified RAN matrices used in Silva et al.(2016)but instead using simple Chinese characters,we used Eyelink 2000 to record eye movements when children named RAN matrices.The results showed that(1)parafoveal preview benefits and load costs were found in all children in three groups finally,(2)we found significant preview benefits only in CA group,which indicated that children in DD and RL group showed less parafoveal preview benefits than CA group,(3)all three groups showed significant parafoveal load costs while there is no difference between DD and CA group.So our results in experiment 1 were in support of the first assumption about parafoveal processing in developmental dyslexia:Children with DD got less parafoveal benefits than CA group.In experiment 2,we took further to study which type of information children in three groups acquired from parafoveal preview.And 11 DD children,11 CA children and 12 RL children participated in experiment 2.We adopted a 3(subject group:DD,RL,CA)X 4(preview type:identical preview,visually similar preview,phonologically similar preview,unrelated control preview)mixed experiment design.In experiment 2,we consistently used a RAN task,while adopted the one-row type.We also adopted the classical boundary paradigm widely used in eye movements,and manipulated four types of preview information:identical preview,visually similar preview,phonologically similar preview,unrelated control preview.As in experiment 1,all three groups completed the naming task and their eye movements were recorded.Finally we found(1)for first fixation duration(FFD),only control groups(CA and RL)acquired visual preview benefits,while DD group showed no preview benefits.However,for gaze duration(GD)and total reading time,all three groups acquired visual preview benefits,(2)none of three groups showed phonological preview benefits in our study.In summary,we got following conclusions in our study:(1)Parafoveal preview benefits in children with developmental dyslexia turned to be less than CA group,while for parafoveal load costs there was no significant difference between groups.(2)For first fixation duration(FFD),only control groups(CA and RL)acquired visual preview benefits,while DD group showed no preview benefits.However,for gaze duration(GD)and total reading time,all three groups acquired visual preview benefits.But none of three groups showed phonological preview benefits in our study.(3)We got evidence in favor of the assumption that DD group acquired less parafoveal preview benefits than controls.Meanwhile,we also found that compared to control groups,DD group showed relatively delay in utilizing and integration of parafoveal information. |
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