Impaired processing of spatiotemporal visual attention engagement deficits in Chinese children with developmental dyslexia.

Emerging evidence suggests that visuospatial attention plays an important role in reading among Chinese children with dyslexia. Additionally, numerous studies have shown that Chinese children with dyslexia have deficits in their visuospatial attention orienting; however, the visual attention engagement deficits in Chinese children with dyslexia remain unclear. Therefore, we used a visual attention masking (AM) paradigm to characterize the spatiotemporal distribution of visual attention engagement in Chinese children with dyslexia. AM refers to impaired identification of the first (S1) of two rapidly sequentially presented mask objects. In the present study, S1 was always centrally displayed, whereas the spatial position of S2 (left, middle, or right) and the S1-S2 interval were manipulated. The results revealed a specific temporal deficit of visual attentional masking in Chinese children with dyslexia. The mean accuracy rate for developmental dyslexia (DD) in the middle spatial position was significantly lower than that in the left spatial position at a stimulus onset asynchrony (SOA) of 140 ms, compared with chronological age (CA). Moreover, we further observed spatial deficits of visual attentional masking in the three different spatial positions. Specifically, in the middle spatial position, the AM effect of DD was significantly larger for the 140-ms SOA than for the 250-ms and 600-ms SOA compared with CA. Our results suggest that Chinese children with dyslexia are significantly impaired in visual attentional engagement and that spatiotemporal visual attentional engagement may play a special role in Chinese reading.