Handedness and visual motion sensitivity in adult dyslexixs

Abstract

Hand preference and sensitivity to coherent motion in random dot patterns were assessed in a large group of adult dyslexics and controls. The aims were to investigate further the hypotheses that dyslexia is associated with (a) anomalous lateralisation, and (b) an impairment of magnocellular visual processing; and in addition, to investigate a possible relationship between anomalous lateralisation and magnocellular function.

Results showed that dyslexia was strongly associated with mixed hand preference, indicative of reduced cerebral lateralisation. Dyslexics also showed reduced visual motion sensitivity, consistent with an impairment of magnocellular visual function. However, independent of dyslexia, nonright-handedness was also associated with poor motion sensitivity, suggesting that there may be a more general relationship between impaired magnocellular function and reduced cerebral lateralisation.