Semantic anomia without surface dyslexia

Abstract

A computational model of oral reading developed by Plaut et al. (1996) proposes that reading aloud low-frequency exception words (e.g. yacht) relies upon a reading pathway that maps semantic representations directly onto output phonology. One prediction of this model is that, if the semantic reading pathway is damaged following brain damage, a pattern of surface dyslexic reading will be observed, characterized by frequent regularization errors when reading aloud low-frequency exception words (e.g. shoe → ‘show’). We report the oral reading of a semantic anomic patient (B.P.) who makes frequent semantic intrusion errors on confrontation naming tasks as well as semantic errors on word-picture and picture-picture matching tasks. Contrary to the prediction of the Plaut et al. (1996) model, B.P.'s oral reading of exception words, including his oral reading of picture names that are exception words, is intact. An important additional feature of B.P.'s language profile is that his oral reading of non-words is poor, suggesting that there is impairment to a phonological reading pathway. We argue that B.P.'s preserved oral reading reflects the operation of a lexical, non-semantic reading pathway.