Lexical constraints on reading accuracy in neglect dyslexia

To elucidate the contribution of attention to reading, a detailed analysis of the performance of a right-brain-damaged patient with neglect dyslexia was conducted. Four-letter words and legal nonwords were presented to the right of ocular fixation for overt naming. More neglect errors occurred with nonwords (60%) than with words (15%). A significant majority of words produced on neglect errors to lexical targets had a higher frequency than the target. Lexical properties of the stimulus affecting neglect error rates were also studied. Examination of a particular source of effect was performed by isolating it from the possible effects of covariates through multidimensional matching. Word frequency had no effect on the rate of neglect errors. However, an increased number of orthographic neighbours that are of a higher frequency than the target and overlap it on their last three letters markedly increased neglect error rates. Neglect errors to words also increased if the first letter of these orthographic neighbours was visually similar to the first letter of the target. Neighbours with a lower frequency than the target had no effect. These results suggest that attention may act on low-level visual mechanisms involved in the encoding of letter shapes. Partial encoding of the letters constituting the target may lead to the activation of lexical representations. This lexical activation tends to be captured by high frequency words compatible with the correctly encoded portion of the stimulus.