Neglect dyslexia and the early stages of visual word recognition

Abstract

Neglect dyslexia is an acquired reading disorder in which one side of words or letter strings is misidentified. Caramazza and Hillis (Cognitive Neuropsychology 1990; 7: 391-445) proposed that the disorder reflects an impairment in the early stages of visual word recognition. Three levels of representation are involved, each with corresponding spatial coordinates. These levels reflect a progression away from the physical stimulus toward a more abstract representation of a word. The errors made by a patient with a level one deficit are relative to the location of a word in the visual field. The errors made by a patient with a level two deficit are relative to the spatial position of a letter(s) within the stimulus. The errors made by a patient with a level three deficit are relative to the ordinal position of a letter(s) within a word. We describe how this model may be used to interpret the differing patterns of performance found in neglect dyslexia and evaluate the model according to 19 published single case studies of neglect dyslexia. It is concluded that the model is well supported by these data and may therefore be viewed as a model of the early stages of reading in intact readers.