Sluggish engagement and disengagement of non-spatial attention in dyslexic children.

Although the dominant view posits that developmental dyslexia arises from a deficit in phonological processing and memory, efficient phonological decoding requires precise visual selection of graphemes. Therefore, visual engagement and disengagement of non-spatial attention were studied in 13 dyslexic children and 13 chronological age and intelligence quotient (IQ) matched normally reading children by measuring "attentional masking" (AM) and "attentional blink" (AB) effects. AM refers to an impaired identification of the first (T1) of two rapidly sequential targets (i.e., attentional engagement). In contrast, AB refers to an impaired identification of the second target in the sequence (T2; i.e., attentional disengagement). The results revealed a specific temporal deficit of AM as well as of AB in dyslexic children. Our results showed that the abnormality in AM and AB is rather widespread, since 77% and 54% of dyslexic children deviated at least 1 standard deviation (SD) from the mean of the controls, respectively, for the two deficits. We further showed that individual differences in non-spatial attention were specifically related to nonword reading ability. These results suggest that non-spatial attention deficits (possibly related to a parietal cortex dysfunction) may selectively impair the reading development via sub-lexical mechanisms.