Top-down influence on phonetic categorization of native vs. non-native speech

Speech perception requires integration of multiple sources of information, including bottom-up acoustic information and top-down contextual information, and listeners may adjust their reliance on a given source of information depending on the communicative context. This work tests the hypothesis that listeners increase reliance on contextual, relative to acoustic, information when listening to a talker with a foreign accent, under the assumption that the bottom-up information (non-native pronunciation) may be less reliable. Native English listeners categorized an utterance-final target word, where the initial consonant systematically varied in voice onset time (VOT), as either “goat” or “coat.” Target words were embedded in carrier sentences contextually biased towards one of the words (e.g., “The girl milked the [coat/goat]” vs. “The girl put on her [coat/goat]”). Stimuli were created from productions by two talkers: a native English talker and a native Mandarin/L2 English talker with a discernable foreign accent. As expected, acoustic information (VOT) was the primary cue for categorization, but sentence context also influenced perception in both talker conditions. Furthermore, preliminary results indicate that the semantic context effect is larger in the Accented than in the Native condition, suggesting that listeners do indeed increase reliance on contextual information when listening to foreign-accented speech.