Callosal function in developmental dyslexia: Evidence of intact hemispheric sharing

It has been suggested that developmental dyslexia may be associated with a deficit in interhemispheric relations (i.e., corpus callosum). We compared normal and dyslexic children on a visual hemispheric sharing task involving the detection of within-field and across-field letter matches. We predicte d that while normal children would show a bilateral field advantage (BFA) ( i.e., across-field advantage) in letter-matching, dyslexics would show a re duced or absent BFA, reflective of deficient interhemispheric functioning. Both groups, however, exhibited highly significant BFA's, the dyslexic BFA being no smaller than the control BFA. These results suggest that certain i nterhemispheric functions involved in hemispheric sharing are preserved in developmental dyslexics. (C) 1999 Academic Press.