Reduced perceptual processing speed and atypical attentional weight at the cores of visual simultaneous processing deficits in Chinese children with developmental dyslexia: a parameter-based assessment of visual attention

Abstract

Individuals with developmental dyslexia usually exhibit a problem in simultaneous processing of multiple visual elements. However, the relationship between impaired visual simultaneous processing (VSP) and reading difficulty is still debated. These inconsistencies may be associated with a wide range of participants’ age, variation in orthographic depth of background languages, and complex subcomponents underlying VSP. The present study thus examined the VSP capacity of children with dyslexia in the language context of Chinese (i.e., a logographic writing system with deep orthography) through the developmental trajectories method in which participants’ age was considered as a continuous variable. This visual multiple-element processing skill was fractionated into four parameters (processing speed, visual short-term memory storage, attentional weight, and irrelevant inhibition) within the framework of the theory of visual attention (TVA). Forty-seven children with dyslexia and fifty-three age-matched normal readers from primary schools were recruited to take a combined TVA test using symbols as non-verbal stimuli. Results showed that the developmental trajectories of children with dyslexia exhibited a delayed pattern in perceptual processing speed and an atypical pattern in attentional weight compared to the controls. Further mediation analyses showed the triangular relationship of “TVA subcomponent-linguistic awareness-reading,” revealing the possible roles of these subcomponents regarding VSP in Chinese reading. The current findings suggested that the VSP deficit of Chinese children with dyslexia may stem from impairments in perceptual processing speed and attentional weight, revealing the possible modulation of language specificity (i.e., Chinese) on cognitive deficits of dyslexia, which may have implications for the diagnosis and remediation of dyslexia.