The selective impairment of phonological processing in speech production

We report the naming performance of a patient (DM) with a fluent progressiv e aphasia who made phonological errors in all language production tasks. Th e pattern of errors in naming was strikingly clear: DM made very many phono logical errors that resulted almost always in nonword responses. The comple te absence of semantic errors and the very low ratio of formal errors relat ive to nonword errors (1.6: 30.3) in DM's performance are discussed in the context of recent claims about the nature of naming deficits in fluent apha sics. We argue that DM's performance makes highly improbable the claim that fluent aphasia results from global lesions affecting all levels of the lex ical access system equally. (C) 2000 Academic Press.