Varieties of pure alexia: The case of failure to access graphemic representations

We document the case of a patient (GV) w ho, following a left posterior brain lesion, showed a selectiv e and sev ere deficit in naming v isual objects and in read ing letters, words, and numerals. Three sets of findings are critical for the interpretation of the patient’s alexia. First, despite intact visual processin g abilities and preserv ed ability to recognise the shape and orientation of letters, GV could not determ ine whether a pair of letters had the sam e name. Second, she should not access the orthographic stru cture and meaning of v isually presented words, although she could access meaning from orally spelled words and she could access orthograp hic structure from m eaning in w ritten words. Third, GV could access partial sem antic information from pictu res and Arabic num erals. Based on this pattern of resu lts, we conclude that the form of alexia manifested by our patient results from failure to access the grap hemic representations of letters and w ords from normally processed visual input. The findings further suggest that access to letter forms and grap heme rep resentation s are sequen-tially ordered stag es of processing in word recog nition. The resu lts also suggest that gra-phemic processin g may be a distinct property of the left hemisphere