关键词: 汉语发展性阅读障碍, 视觉同时性加工技能, 视觉注意理论, 知觉加工速度, 选择性空间注意分布

Abstract:

Chinese children with developmental dyslexia (DD) have been found to show a deficit in processing multi-elements in a variety of visual tasks parallelly. Nevertheless, the potential mechanisms of this visual simultaneous processing deficit and its relation to the reading ability still remain unclear. The ability of simultaneously processes multi-character strings is restricted by different cognitive components, including perceptual processing speed, visual short-term memory capacity, selective spatial attention distribution pattern, and the ability to inhibit distractors. Therefore, this article attempted to explore the potential mechanisms underlying the visual simultaneous processing in Chinese children with DD in the framework of the theory of visual attention (TVA). Two experiments are conducted to investigate the fundamental cognitive components regarding the visual simultaneous processing skill, with further examining the relationship between these components and the Chinese reading ability from developmental perspective.
43 Chinese children with DD and 46 chronological-age matched children with normal reading ability are recruited, and the two groups respectively include students from high and low grades in primary schools for the purpose of probing into the developmental changes in these TVA-based components of the visual simultaneous processing. The two experiments separately utilize high-frequency Chinese characters as verbal materials and the symbols as nonverbal materials. A modified combined theory of visual attention (CombiTVA) paradigm is employed to collect participants’ performances during the multi-element processing. Based on the response accuracy in each level of CombiTVA task, the four parameters including processing speed (C), visual short-term memory storage (K), attentional weight (ω), and irrelevant inhibition (α) are estimated through TVA model.
We first compare the four TVA parameters between groups and grades, and then conduct hierarchical regression analyses to examine the contributions of possible impaired TVA parameters of reading difficulty. The results of the two experiments illustrate that the DDs from high and low grades both exhibit reduced perceptual processing speed comparing to the controls during processing multiple elements in parallel, with a trend of developmental decrease in this component deficit. Moreover, significant differences in the selective spatial attention distribution pattern between dyslexic and normal readers are only present in Experiment 1 with Chinese characters as the stimuli rather than in Experiment 2 with the nonverbal symbols as the stimuli. In details, during multi-processing of Chinese characters, a balanced pattern in attentional distribution is observed in DDs from both two grade groups; while the attentional weight of normal readers develops from right-lateralized to balanced patterns. Further hierarchical regression analyses reveals that the impaired components of visual simultaneous processing are separately associated with different levels of Chinese reading, the component of perceptual processing speed independently and effectively accounts for the variance of the sentence reading performance regardless of material properties, while the component of selective spatial attention distribution pattern is related to the single-character reading speed. These findings unfold the modulation of language specificity of Chinese to the cognitive deficits of DDs to some extent.
This research is helpful to deepen our understanding of the internal mechanism of the visual simultaneous processing deficit in Chinese dyslexic children, and contribute to designing relevant intervention targeting visual simultaneous processing skills to improve reading efficiency in the dyslexics.

Key words: Chinese developmental dyslexia, visual simultaneous processing skill, theory of visual attention, perceptual processing speed, selective spatial attention distribution pattern