Rate of information segregation in developmentally dyslexic children

Slowed processing of sequential perceptual information is related to develo pmental dyslexia. We investigated this unimodally and crossmodally in devel opmentally dyslexic children and controls ages 8-12 years. The participants judged whether two spatially separate trains of brief stimuli, presented a t various stimulus onset asynchronies (SOA) in one or two senses, were sync hronous or not. The stimulus trains consisted of light flashes in vision, c licks in audition, and indentations of the skin in the tactile sense. The d yslexic readers required longer SOAs than controls for successful performan ce in all six comparisons. The crossmodal spatiotemporal resolution of the groups differed more than unimodal performance. The dyslexic readers' segre gation performance was also less differentiated than that of the controls. Our results show that not only sensory hut also polysensory nonverbal infor mation processing is temporally impaired in dyslexic children. (C) 2000 Aca demic Press.