Visual,Auditory And Cross-modal Temporal Sensitivity Of Chinese Children With Developmental Dyslexia And Their Effects On Reading Abilities

Temporal sensitivity refers to the ability of individuals to perceive the time of stimulus presentation.Visual,auditory unimodal and audiovisual cross-modal processing are important components of the cognitive processing of reading.The temporal processing deficits theories about developmental dyslexia(DD),such as rapid auditory processing theory,magnocellular theory,and audiovisual integration theory believed that DD was the results from temporal sensitivity deficits in visual,auditory unimodal and audiovisual cross-modal.There is the different cognitive processing of reading between the alphabetic language and Chinese language.However,it remains a lot of unknowns on the visual,auditory unimodal and audiovisual cross-modal temporal sensitivity of the Chinese children with DD.The purpose of the study is to explore the developmental characteristic of the visual,auditory unimodal and audiovisual cross-modal temporal sensitivity in Chinese children with DD and the paths that their effects on the reading fluency and Chinese character recognition.It will help provide theoretical and practical basis for the intervention of children with DD.53 children with DD in grade 3 to 5 and 53 age-matched typically developing(TD)children participated in this study.This study consists of three parts.The purpose of the first part(Study 1)was to investigate whether the children with DD have temporal sensitivity defects in visual and auditory unimodal.Study 1 involved two sub-studies,Experiment 1 and Experiment 2,which visual and auditory temporal order judgment(TOJ)tasks were used respectively to compare the difference in visual and auditory temporal sensitivity between children with DD and TD.Through comparing the accuracy rate and reaction times of both modality TOJ tasks of the two groups of children,the hypothesis that the children with DD have deficits in visual and auditory temporal sensitivity were verified.The purpose of second part(Study 2)was to investigate whether children with DD have defects in audiovisual cross-modal temporal sensitivity,whether children with DD and TD have the same developmental order in visual and auditory unimodal and cross-modal time sensitivity,and whether the degree of cognitive processing will affect children’s audiovisual cross-modal temporal sensitivity.Study 2 includes three sub-studies,Experiment 3,Experiment 4 and Experiment 5.In Experiment 3,the audiovisual TOJ task was used to examine the difference in audiovisual cross-modal temporal sensitivity between DD and TD children.The results show that children with DD have deficits in audiovisual cross-modal temporal sensitivity.Under the condition that visual stimuli are presented before auditory stimuli(VA order),the audiovisual cross-modal temporal sensitivity of children with DD lags significantly behind TD children.In Experiment 4,an audiovisual synchrony judgment(SJ)task was used to examine whether the cross-modal temporal sensitivity of children with DD still lags behind TD children,and whether there are significant differences in the simultaneity time windows of the two groups of children under the condition of further reducing the extra cognitive processing.The results show that in the audiovisual SJ task,the audiovisual temporal sensitivity of children with DD still lags behind that of TD.Similarly,under the VA order,the audiovisual time window of children with DD is significantly greater than that of TD children.Further validated the hypothesis that DD children have deficits in audiovisual cross-modal temporal sensitivity under the VA order.Experiment 5 is a comparative study of temporal sensitivity of different modes.It consists of two parts.In the first part,the performance in visual and auditory unimodal and cross-modal TOJ tasks of children with DD and TD were compared in order to investigate the development sequence of children’s different modal temporal sensitivity.The results show that children’s unimodal temporal sensitivity is better than cross-modal temporal sensitivity;auditory temporal sensitivity is better than visual temporal sensitivity,and children with DD and TD have a consistent developmental sequence.In the second part of this experiment,the performance of children with DD and TD on the audiovisual cross-modal TOJ task and the audiovisual SJ task are compared.The results showed that the two groups of children performed better on the temporal order judgment task,indicating that extra cognitive processing can affect children’s audiovisual cross-modal temporal sensitivity.The purpose of the third part(Study 3)is to investigate the cognitive processing pathways that the visual,auditory unimodal and audiovisual cross-modal temporal sensitivity affects reading fluency and Chinese character recognition.Study 3 is consisted of two sub-studies.Sub-study 1 is a correlation study of visual,auditory unimodal and audiovisual cross-modal temporal sensitivity,reading cognitive skills,reading fluency and Chinese character recognition.In the sub-study,the differences in the three reading cognitive skills including phonetic awareness,orthographic processing,and rapid naming were compared between the children with DD an TD first.Subsequently,the correlation between visual,auditory unimodal and cross-modal temporal sensitivity,reading cognitive skills and reading fluency and Chinese character recognition was investigated.The research results show that children with DD lag behind TD in phonetic awareness and rapid naming skills.There is a significant correlation between visual,auditory unimodal and cross-modal temporal sensitivity,reading cognitive skills,reading fluency and Chinese character recognition.In Sub-study 2,path models were proposed and examined,in which visual,auditory unimodal and audiovisual cross-modal temporal sensitivity affect reading fluency and Chinese character recognition through the mediating role of reading cognitive skills.The results show that visual,auditory unimodal and cross-modal temporal sensitivity can directly or indirectly predict reading fluency and Chinese character recognition through the mediating role of rapid naming.Cross-modal temporal sensitivity and rapid color naming play a multi-mediating role between visual temporal sensitivity and reading fluency,as well as visual temporal sensitivity and Chinese character recognition.However,the mediating effects of phonetic awareness and orthography processing are not significant.The results suggest that the visual,auditory unimodal and cross-modal temporal sensitivity could affect the reading fluency and Chinese character recognition by affecting the speed of grapheme–phoneme mapping.Innovation of this study: this study systematically investigated and revealed the development characteristics of visual,auditory unimodal and cross-modal temporal sensitivity of children with DD and the developmental order of the temporal sensitivity of three modals,found the relationship between visual,auditory unimodal and cross-modal temporal sensitivity,as well as their relationship with reading cognitive skills,reading fluency and Chinese character recognition.In addition,this study proposed and examined the path models that visual,auditory unimodal and audiovisual cross-modal temporal sensitivity effect reading fluency and Chinese character recognition through the mediating roles of reading cognitive skills.It provided Chinese language evidences support for the theory of temporal processing deficits in DD,and also provided theoretical and practical basis for the intervention of Chinese children with DD based on visual,auditory and audiovisual temporal processing training.The limitation of this study is that it does not examine the visual,auditory unimodal and cross-modal temporal sensitivity of children at the linguistic level.In addition,it is the lack of intervention studies on temporal sensitivity of children with DD in this study.