The Characteristics Of Visual Attention Span In Dyslexic Primary School Students

Developmental dyslexia is one of the most common forms of learning disabilities and has a significant impact on an individual's lifelong development.The causes of dyslexia have always been concerned by researchers.It is now accepted that dyslexia is caused by multiple deficit.Bosse(2007)believe that the visual attention span reflects the visual processing ability of individuals to process distinct visual elements in parallel in a multi-element array,and the reduced visual attention span is a underlying cognitive deficit in dyslexia.To examine this hypothesis,researchers tested the visual attention span skills of dyslexic individuals by the string processing tasks.Nevertheless,some studies found visual attention span deficits in dyslexic individuals,while others found normal visual attention span.Previous studies have shown that the material complexity may be the reason for the discrepancy of the two types of research findings.Therefore,this study used materials of different complexity to measure the visual attention span of dyslexic children and normal children.A total of 15 participants who met the diagnostic criteria for dyslexia were selected from178 children of grade 5 and 6 in a primary school in dalian city,and 15 children with normal reading were selected as the matching group.High frequency Chinese characters that dyslexic children can master were selected as experimental materials.Five characters drawn with 3strokes form a simple character string,and five characters drawn with 9 strokes form a complex character string.Experiment 1 used the array recognition task and experiment 2 used the single-character recognition task respectively to investigate the visual attention span of Chinese dyslexic children.Experiment 1 adopted a mixed experimental design of 2(group: dyslexia group,age matching group)* 2(material complexity: simple,complex),and the dependent variables were the correct rate of response and d' value.The results showed that the main effects of group and complexity were extremely significant.The correct rate and d' value of Chinese character strings were significantly lower in the dyslexic group than those in the age-matched group.At the same time,it is found that the material complexity has a great influence on the visual attention span.In experiment 2,the change detection task of partial recognition condition was adopted to control the possible impact of working memory span damage on the task.The results also showed that there were significant differences between dyslexic group and age-matched group in the accuracy and the d' value of recognition tasks.This study examined the visual attention span of dyslexic children and normal children in processing high-frequency Chinese characters and found that Chinese dyslexic children have visual attention span deficit.It is also found that the complexity of materials affects the recognition process of Chinese readers in the change detection task,but not the visual parallel processing.This study provides a new way for the intervention and training of Chinese developmental dyslexia by increasing visual attention span.