Lateral asymmetry in subgroups of dyslexic children

It has been proposed that in examining hemispheric dominance in dyslexics, investigators must make a distinction between subtypes of the disorder. Using the Denver Reading and Spelling Test, 72 dyslexics were divided into three groups: dysphonetics, dyseidetics, and nonspecifics. Three measures of hemispheric dominance were administered: a dichotic listening test, a hemiretinal test with linguistic stimuli, and a hemiretinal test with spatial stimuli. Results indicated that the three subgroups of dyslexics did not differ from one another on measures of hemispheric dominance. Dyslexics, taken as a group, tended to show an exaggerated right ear advantage on the dichotic listening test, in comparison with that of controls. It was proposed that the dichotic listening test may be confounded by attentional deficits in the dyslexics.