Word-centred neglect dyslexia: evidence from a new case

Neglect dyslexia resulting from damage to word-centred representations is extremely rare. We report on a new case. A left-handed subject, SVE, presented with aphasia and neglect dyslexia/dysgraphia following a right hemisphere stroke. In tachistoscopic reading tasks, some of his errors resulted from retina-centred neglect, as he responded more accurately to words flashed in the left visual field than to words flashed in the right visual field. However, the critical aspects of his reading performance indicated word-centred neglect. SVE incorrectly produced the initial elements of four-letter words, regardless of stimulus location (to the left and to the right of fixation, or at fixation), and orientation (horizontal and vertical presentation). A similar distribution of errors was demonstrated in writing (very inaccurate performance on initial letters). This pattern of performance suggests damage to an abstract letter string representation defined by spatial coordinates, rather than to an ordering mechanism. It is most naturally accommodated by models of word recognition which assume a word-centred level of representation, 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 computing word-centred representations.