Durations of recognition for single letters, with and without visual masking, by dyslexics and normal readers.

Two sets of letters, i.e., those subject to reversal/rotation such as b, d, p, and q, and others, e, i, u, w, x, and o, were tachistoscopically presented singly to 15 normal readers (aged 6 to 14 yr.) and 29 dyslexic children (aged 7 to 13 yr.). Half the presentations were subject to masking by visual noise. Contrary to a prediction based on temporal-sequencing deficiency, the dyslexics required a significantly longer time than normals for recognition. This occurred under both the masked and non-masked conditions. Reversible/rotational letters gave more difficulty than other letters only when masked, for both normals and dyslexics. This supports the hypothesis that these letters have no special relation to dyslexia. The view that dyslexia is a developmental anomaly was supported by the finding of a significant correlation between recognition-speed and age for the normal readers only.