The Different Roles of Expectations in Phonetic and Lexical Processing

The way people speak reflects their demographic background. Listeners exploit this contingent variation and make use of information about speakers’ background to process their speech. Evidence for this comes from both phonetic and lexical tasks, and the two are assumed to tap into the same mechanism and provide equivalent results. Curiously, this assumption has never been tested. Additionally, while it has been established that expectations can influence language processing in general, the role of individual differences in susceptibility to this influence is relatively unexplored. We investigate these two questions in the context of Southern and General American speech varieties in the USA. We show that phonetic and lexical tasks are not equivalent, and furthermore, that the two are driven by mechanisms that are sensitive to different individual variables: while performance at the lexical level is influenced by implicit bias, performance at the phonetic level is influenced by working memory. These results thus change our understanding of how expectations influence processing, and have implications for how to conduct and interpret studies on the topic.