Native ‘um’s elicit prediction of low-frequency referents, but non-native ‘um’s do not

• Disfluencies in speech may guide listeners’ predictive strategies.
• Native disfluencies elicited prediction of low-frequency referents.
• Non-native disfluencies did not guide prediction of low-frequency referents.
• Listeners draw inferences about the possible source of disfluency.
• Listeners adapt their predictive strategies when listening to non-native speech.

Speech comprehension involves extensive use of prediction. Linguistic prediction may be guided by the semantics or syntax, but also by the performance characteristics of the speech signal, such as disfluency. Previous studies have shown that listeners, when presented with the filler uh, exhibit a disfluency bias for discourse-new or unknown referents, drawing inferences about the source of the disfluency. The goal of the present study is to study the contrast between native and non-native disfluencies in speech comprehension. Experiment 1 presented listeners with pictures of high-frequency (e.g., a hand) and low-frequency objects (e.g., a sewing machine) and with fluent and disfluent instructions. Listeners were found to anticipate reference to low-frequency objects when encountering disfluency, thus attributing disfluency to speaker trouble in lexical retrieval. Experiment 2 showed that, when participants listened to disfluent non-native speech, no anticipation of low-frequency referents was observed. We conclude that listeners can adapt their predictive strategies to the (non-native) speaker at hand, extending our understanding of the role of speaker identity in speech comprehension.