ERPs to orthographic, phonological, and semantic tasks in dyslexic children with auditory processing impairment

Abstract

Event‐related potentials were recorded in 25 dyslexic children with auditory processing deficits and 25 normal children, 7 to 12 years old. Three tasks were run: orthographic, phonological, and semantic classification tasks. N2 and P3 latencies and P3 amplitude (P3amp) and reaction times (RT) to targets were measured. No significant RT differences were found between the groups although a group, age, and task interaction was seen. P3 latencies decreased with age across tasks, and N2 latencies decreased with the semantic and phonological tasks. P3 latencies were significantly longer in dyslexic than control children in the phonological and semantic tasks; for the latter task, dyslexics also had longer N2 latencies. In the phonological task, latencies decreased with age only for the control children; the dyslexic children showed no maturational changes. Across tasks, there were significant distributional group differences in the P3, due to a more posteriorly located P3, and marked frontal negativity in the dyslexics. These data are consistent with a model of an underlying processing deficit. However, in this group of dyslexic children with auditory dysfunction, the most marked impairment was seen in the phonological task.