Dyslexia and the centre-of-gravity effect

When human observers are presented with a double target display, a saccadic eye movement is triggered to an intermediate position close to the 'centre -of-gravity' of the configuration. This study examined the saccadic eye mov ements of dyslexic and normal readers in response to displays of single and double targets. Eye movement analyses revealed no differences in the spati al position of saccadic eye movements of dyslexic and normal readers in res ponse to single targets presented at 5 degrees or 10 degrees. However, when presented with two targets simultaneously at 5 degrees AND 10 degrees, in contrast to normal readers who generated saccades to an intermediate positi on between the two targets (towards the 'centre-of gravity'), dyslexics gen erated saccades that landed close to the near target eccentricity. These fi ndings suggest that dyslexia is associated with a deficit in the processing of global spatial information for the control of saccadic eye movements.