Dyslexia and attentional shifting.

Dyslexia is a neurocognitive deficit primarily expressed in reading difficulties, but also affecting non-linguistic performance. Several studies report that dyslexics perform differently in the attentional blink paradigm, which indicates an impaired capacity to rapidly shift visual attention. However, attentional shifting can occur at different levels of cognitive processing, and it is unclear whether dyslexic attentional shifting is impaired at all levels, or only at the peripheral levels. We studied performance on a task-switching paradigm by dyslexics and normal readers to test whether the difficulty with attentional shifting occurs at the level of central cognitive processing. We found no specific impairments in task-switching in dyslexics. However, dyslexics performed generally much more slowly across all conditions than normal readers. We conclude that while dyslexics have a problem with attentional switching at a perceptual level, their capacity to rapidly switch between tasks is normal. Our findings add to previous studies indicating that dyslexic problems with shifting visual attention are caused by anomalies in more peripheral neural pathways, such as the magnocellular layers in the lateral geniculate nucleus.