The perceptual span in dyslexic reading and visual search.

Many studies have attempted to identify the root cause of dyslexia. Different theories of dyslexia have proposed either a phonological, attentional, or visual deficit. While research has used eye-tracking to study dyslexia, only two previous studies have used the moving-window paradigm to explore the perceptual span in dyslexic reading, and none have done so in visual search. The present study analysed the perceptual span using both reading and visual search tasks to identify language-independent attentional impairments in dyslexics. We found equivocal evidence that the perceptual span was impaired in dyslexic reading and no evidence of impairment in visual search. However, dyslexic participants did show deficits in the visual search task, with lower search accuracy and shorter saccades compared with controls. These results lend support for a visual, rather than attentional or phonological, account of dyslexia.