Visuospatial Perception and Reading Problems

Developmental dyslexia probably results from minor disorganisation of the specialisation of the two cerebral hemispheres. The consequences of impairment of the visuomotor and visuospatial functions of the right hemisphere are considered here. Many dyslexics complain that small letters appear to blur and move around, symptoms that are associated in these children with distorted vergence control, unstable binocular fixation, impaired visual direction sense and reduced stereoacuity. All these abnormalities are also characteristic of patients with lesions of the right posterior parietal cortex. Evidence is presented here that dyslexic children with unstable binocular control show specific signs of disordered development of the right posterior parietal region, including a tendency to left neglect, very inaccurate localisation of dots in the left hemifield and marked instability of the left eye during convergent fixation. Hence it is concluded that many dyslexic children suffer disordered development of the visuomotor processing functions of the right hemisphere, and that this causes many of their reading problems. © 1989, Psychological Society of Ireland. All rights reserved.