SURFACE DYSLEXIA AND SURFACE DYSGRAPHIA - TREATMENT STUDIES AND THEIRTHEORETICAL IMPLICATIONS

We report studies of a patient with acquired surface dyslexia and dysg raphia. His reading impairment was treated using the methods previousl y reported to be successful for surface dyslexia by Byng and Coltheart (1986); these methods were also successful with our patient. In addit ion, we observed, as Byng and Coltheart did, that when these methods a re used there is incomplete but significant generalisation to the read ing of untreated words. Connectionist simulations of the effects of da mage to the language-processing system have taken this generalisation effect to be evidence that words are represented in a distributed fash ion in that system; we challenge this inference, on the basis of data from our and Byng and Coltheart's patient. Our patient's spelling impa irment was treated using the methods previously reported to be success ful for surface dysgraphia by Behrmann (1987); these methods were also successful for our patient, and we found in addition, as did Behrmann , that the treatment effects upon spelling did not generalise to the s pelling of untreated words. We consider the implications of our result s for the theoretical issue of whether lexical reading and lexical spe lling depend upon a common orthographic lexicon or upon separate input and output orthographic lexicons. Although our results were not entir ely unequivocal in relaton to this issue, we interpret the evidence fr om our patient, and from analyses we report of data from the surface d yslexic and surface dysgraphic patient described by Behrmann and Bub ( 1992), as favouring the two-lexicon view.