SHIFTING OF ATTENTION IN SUBTYPED DYSLEXIC-CHILDREN - AN EVENT-RELATED POTENTIAL STUDY

The behavioral and electrophysiological correlates of the ability to shift attention was investigated in 9- to 12-year-old children, 22 L-dyslexic, 21 P-dyslexic, and 25 normal readers. L-dyslexia presumably is associated with premature generation of left-hemispheric reading strategies and P-dyslexia is associated with the perseverant generation of right-hemispheric strategies. Subjects were presented a task developed by Posner et al. that requires the covert shift of attention to a spatial location and a response to an imperative stimulus that appears in the cued or uncued visual field. In agreement with previous findings, valid information (coincidence of cue and stimulus) elicited faster reaction times and fewer errors than invalid information (non-coincidence of cue and stimulus). Contrary to predictions neutral cues elicited the slowest and most accurate responses. No effect of group was found. Cue- and stimulus-related event-related potentials (ERPs) generally were pronounced over the right posterior brain regions, especially when cue and imperative stimulus coincided in the left visual field. This finding indicates the involvement of posterior brain areas in orienting and control of attention. Group differences, dependent on cue-stimulus coincidence, were found in early ERP responses to the imperative stimulus.