Electrophysiological correlates of visual attention span in Chinese adults with poor reading fluency

Individuals with reading fluency difficulty (RFD) show an impairment in the simultaneous processing of multiple elements, which could be reflected in their visual attention span (VAS) capacity. However, the relationship between VAS impairment and RFD is still controversial. A series of processes underlie VAS, such as the early stage of visual attentional processing and the late stage of allocating and maintaining attentional resources. Therefore, the present study explored the relationships between VAS skills and RFD through the event-related potential (ERP) technique to disentangle the contributing cognitive processes regarding VAS from a temporal perspective. Eighteen Chinese adults with poor reading fluency and 18 age-matched normal readers participated. Their VAS skills were measured by a visual one-back task with symbols as nonverbal stimuli and key pressing as nonverbal responses, while relevant electrophysiological signals were recorded. The results showed that lower d' values and abnormal electrophysiological activities (especially weak amplitudes in the N1 and P3 components) in the VAS task were observed for the nonfluent readers compared with the controls. These findings suggested that the low VAS capacity in adults with poor reading fluency could be reflected by problems both in directing selective attention to visually discriminate stimuli within a multielement string at the early processing stage and in allocating attention to further encode targets at the late processing stage. Alternative explanations were further discussed. The current results provide theoretical explanations of the VAS-RFD relationship from a temporal perspective and provide insights for future remediation of reading fluency difficulty.