• laterality;
  • dyslexia;
  • genetics

Summary The lateral preferences and L-R skill of 109 male and 20 female dyslexics were as expected if the distribution of lateral asymmetry is shifted less far to the right in dyslexics than in controls. Several aspects of the data were consistent with Annett's hypothesis that some dyslexics lack the left hemisphere speech-organising factor postulated by the right shift theory of handedness and that this would be sufficient to account for the proportion of affected relatives. Some, dyslexics were strongly dextral and these differed from the less dextral cases in several ways which resembled the distinction between backward and retarded readers.