Binocular advantage and visual processing in dyslexic and control children as measured by visual evoked potentials.

The role of visual processing in dyslexia continues to stir controversy. Previous research using early components of visual evoked potentials (VEP's) has revealed differences in visual processing between dyslexics and controls. VEP's have successfully indexed binocular advantage. Intrasensory functioning could conceivably be deficient in dyslexics. This study recorded VEP's in response to contrast-reversing checkerboards binocularly and monocularly from dyslexic and control children. The overall monocular and binocular amplitudes of the major positive peaks (P100) were greater for controls than dyslexics; however, contrary to the original hypothesis, the magnitude of binocular advantage was higher for dyslexics than for the control children. Stimulus factors had an effect, but did not interact with reading ability.