Response biases in oral reading: an account of the co-occurrence of surface dyslexia and semantic dementia.

This paper reports a case study of a subject (EP) with a progressive impairment of semantic memory and a coincident surface dyslexia. These two disorders frequently occur together, but their association is not readily explained within current models of reading. This study investigated two theories that offer different principled accounts of this association, the "semantic glue hypothesis" (Patterson & Hodges, 1992) and the "summation hypothesis" (Hillis & Caramazza, 1991) and found both hypotheses wanting. Instead it was shown that when vestiges of word meaning remained, a lexical response was preferred, but when meaning was lost entirely, the evidence derived from sublexical processing appeared to bias selection of the response towards the regularized form.