Word-centred neglect dyslexia: Evidence from a new case

Neglect dyslexia resulting from damage to word-centred representations is e xtremely rare. We report on a new case. A left-handed subject, SVE, present ed with aphasia and neglect dyslexia/dysgraphia following a right hemispher e stroke. In tachistoscopic reading tasks, some of his errors resulted from retina-centred neglect, as he responded more accurately to words flashed i n the left visual field than to words flashed in the right visual field. Ho wever, the critical aspects of his reading performance indicated word-centr ed neglect. SVE incorrectly produced the initial elements of four-letter wo rds, regardless of stimulus location (to the left and to the right of fixat ion, or at fixation), and orientation (horizontal and vertical presentation ). A similar distribution of errors was demonstrated in writing (very inacc urate performance on initial letters). This pattern of performance suggests damage to an abstract letter string representation defined by spatial coor dinates, rather than to an ordering mechanism. It is most naturally accommo dated by models of word recognition which assume a word-centred level of re presentation, and cannot be explained by models which do not include such a representational level. Consideration of our subject in the light of other similar reports prompts hypotheses on the neural mechanisms involved in co mputing word-centred representations.