What are you sinking about? Experience with unfamiliar accent produces both inhibition and facilitation during lexical processing

Speech produced with an unfamiliar accent may pose a challenge for listeners, resulting in delayed processing and/or decreased intelligibility. Such costs may be due to a mismatch between listeners’ experience with how a given sound category is phonetically realized, and how it is implemented by an unfamiliar speaker. Phonetic mismatches can increase processing time, but listeners could avoid them by adjusting their expectations for a given speaker or speech variety. This study investigates how changes in phonetic category structure may facilitate (or inhibit) processing of novel words produced with either the same or a phonetically similar accent, asking whether such adaptation is driven by a targeted shift or expansion of phonetic category boundaries. An artificial accent was created by morphing voiceless fricatives /θ/ and /s/ to create phonetically ambiguous [θ/s], which was presented in disambiguating /θ/ word frames (e.g., hypo[θ/s]etical). To examine the effect of phonetic learning on word processing, listeners were divided into three groups and asked to complete an exposure task where they heard either (1) accented critical /θ/ words, (2) natural (unaccented) /θ/ words, or (3) no /θ/ words. All listeners then completed a cross-modal priming task where, across two experiments, they were tested on their processing of words produced with the same artificial accent or three related accents differing in their phonetic match to the training accent. Overall, results show that while there was no effect of prior exposure on processing of novel words produced with the exposure accent, listeners with prior accent exposure showed a distinct pattern of facilitation and inhibition when processing words produced with the novel accents, compared to listeners with no prior accent exposure. Interestingly, listeners with prior exposure to unaccented /θ/ words tended to pattern with the accented /θ/ exposure group, rather than with controls. The role of acoustic/perceptual similarity and prior experience are discussed, along with implications of these results for a category expansion mechanism of phonetic learning.

All data, stimuli, and code for this study are freely available on OSF via https://osf.io/xw5k3/.