Preserved access to abstract letter identities despite abolished letter naming in a case of pure alexia

In this paper, we discuss the letter processing difficulties of a patient (MS) with pure alexia after left hemisphere stroke who is unable to read any words aloud despite preserved writing and good performance at naming orally spelled words. MS is completely unable to name visually presented letters even though she can name them when they are presented in other modalities. Despite her poor naming, she can distinguish correctly oriented letters from mirror reversals and can perform accurate cross-case matching of visually presented letters. It, therefore, appears that MS is able to access the abstract identity of visually presented letters despite her total inability to name them. This is a more precise form of letter processing impairment than that which has been reported in previous cases of pure alexic patients who are unable to name visually presented letters [Caplan, L.R., & Hedley-White, T. (1974). Cueing and memory function in alexia without agraphia: a case report. Brain, 115, 251-262, Miozzo, M., & Caramazza, A. (1998). Varieties of pure alexia: the case of failure to access graphemic representations. Cognitive Neuropsychology, 15, 203-238; Sevush, S., & Heilman, K.M. (1984). A case of literal alexia. Brain & Language, 22, 92-108]. It suggests that representations of the graphemic identities of letters used in reading are either modality specific or else they are hemisphere specific [Saffran, E.M., & Coslett, H.B. (1998). Implicit vs. letter-by-letter reading in pure alexia: a tale of two systems. Cognitive Neuropsychology, 15, 141-165]. Her letter processing impairment also appears to be different from that observed in a letter-by-letter reader [Perri, R., Bartolomeo, P., & Silveri, M.C. (1996). Letter dyslexia in a letter-by-letter reader. Brain & Language, 53, 390-407] who could name visually presented letters with reasonable degrees of accuracy despite a difficulty in processing their abstract identity. (C) 2001 Elsevier Science Ltd. All rights reserved.