Finding levels of abstraction in speech production: evidence from sound-production impairment.

A widely held view in linguistics and psycholinguistics is that there are distinct levels of processing for context-independent and context-specific representations of sound structure. Recently, this view has been disputed, in part because of the absence of clear evidence that there are abstract mental representations of discrete sound-structure units. Here, we present novel evidence that separate context-independent and context-specific representations of sound structure are supported by distinct brain mechanisms that can be selectively impaired in individuals with acquired brain deficits. Acoustic data from /s/-deletion errors of 2 aphasic speakers suggest both a phonological level of processing at which sound representations (e.g., /p/) do not specify context-specific detail (e.g., aspirated or unaspirated) and a distinct level at which context-specific information is represented. These data help constrain accounts of sound-structure processing in word production and crucially support the claim that context-independent linguistic information affects language production.