Neural recordings of continuous speech reveal robust signatures of prediction in second language learners of English

Abstract

When listening to speech in their native language, speakers use prior context to anticipate upcoming phonemes, words, and concepts, integrating information at the sublexical, lexical, and sentence level. While it has been suggested that late second language learners do not predict to the same extent as native listeners, adequately evaluating this claim requires measurement of predictions at these multiple levels of representation simultaneously in natural speech. We recorded magnetoencephalography (MEG) responses from native Mandarin and Sinhala speakers listening to continuous narrative English speech. We used multivariate temporal response function (mTRF) analysis to investigate whether second language listeners demonstrate the same markers of prediction in neural data as native English speakers listening to the same stimuli. We demonstrate that late second language listeners exhibit strikingly similar responses to native speakers in sensitivity to phoneme surprisal and entropy with respect to sublexical, lexical, and sentence-level context. The few small response differences we observed appear most likely to arise from specific properties of the native languages, rather than general differences between native and second-language listening. These results provide evidence that late second-language listeners indeed leverage prediction in similar ways as native listeners in understanding continuous speech. This suggests that multivariate analyses of neural data from naturalistic listening may be vital in carefully evaluating the differences and similarities in speech prediction across populations. Significance StatementMuch is still unknown about how people listening to a second language predict upcoming words and sounds. Here, we leverage neuroimaging during continuous speech and analyze responses to multiple speech language features in the signal to study the neural encoding of prediction simultaneously at multiple levels of linguistic context. We observe robust encoding of statistical properties tied to prediction at all context levels in second-language learners of English and that responses are strikingly similar between native and second language listeners. Speech language features are encoded similarly in both groups of language learners, with few differences between the native and second language listeners, indicating that second language listeners predict upcoming input similarly to native listeners.