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The neural basis of lexical tone in bilingual language processing
Poster Session A - Sandbox Series, Thursday, October 24, 10:00 - 11:30 am, Great Hall 3 and 4
This poster is part of the Sandbox Series.
Xindong Zhang1, Judy D. Zhu2, Paul F. Sowman3,4, Xin Wang1; 1Department of Linguistics, Macquarie University, 2School of Psychological Sciences, Macquarie University, 3School of Clinical Sciences, Auckland University of Technology, 4Faculty of Medicine, Health and Human Sciences, Macquarie University
Mandarin-English bilinguals use pitch to disambiguate lexical meanings in one language but not the other. Previous studies show that these bilinguals are more sensitive to pitch information even when it is not used to differentiate lexical meanings, such as in a non-tonal language like English (Ortega-Llebaria et al., 2017; Wang et al., 2020; Wong et al., 2004). Here, we investigate the neural basis of lexical tone processing in Mandarin-English bilinguals when they perform a task exclusively in English. We ask whether they use pitch information when processing interlingual homophones (IHs), i.e. words that overlap in phonology across language but differ in spelling, meaning or grammatical class. Some of the IHs used in the study are superimposed with four different Mandarin tones. In addition, a control group of monolingual English speakers is tested to show the difference in pitch processing. We hypothesize that Mandarin-English bilinguals will exhibit greater sensitivity to the linguistic features of tones than monolingual English speakers. Magnetoencephalography (MEG) was used to record brain signals to compare the brain activities during lexical tone processing between Mandarin-English bilinguals and monolingual English speakers. Both IHs and non-IHs, which were CV (consonant-vowel) monosyllabic English words, were selected to test the IH effect. We employed the oddball paradigm in which an oddball (or deviant) stimulus was presented within a stream of regularly repeated ‘standard’ stimuli. In the auditory word sequences, the standards were the natural English pronunciation of IHs and non-IHs. At the same time, four Mandarin tones were imposed on IHs and non-IHs, forming four deviant types. We followed the tone superimposition technique established in Wang et al (2024) to create speech tokens of good quality. In each word sequence, only one lexical tone was presented (e.g., tea3/ti3/ as the deviant in tea/ti/ sequence). Thus, it is a 2 (monolinguals vs. bilinguals) x 4 (Tone 1 vs. T2 vs. T3 vs. T4) x 2 (IH vs. non-IH) design. Data collection is ongoing. Since lexical tone processing is highly relevant to the left hemisphere (LH), we predict that bilinguals will elicit an enhanced LH activity relative to monolingual English speakers when processing deviant IHs but not non-IHs. This is because the IHs have shared phonological representations between Mandarin and English. In contrast, only one language is relevant for the monolingual English speakers. Multivariate pattern analysis will be used for further analysis. Ortega-Llebaria, M., Nemoga, M., & Presson, N. (2017). Long-term experience with a tonal language shapes the perception of intonation in English words: How Chinese–English bilinguals perceive “Rose?” vs. “Rose.” Bilingualism: Language and Cognition, 20(2), 367–383. Wang, X., Hui, B., & Chen, S. (2020). Language selective or non-selective in bilingual lexical access? It depends on lexical tones! PLOS ONE, 15(3), e0230412. Wang, X., Jheng, J., & McMurray, B. (2024). Tone Superimposition Technique in Speech Sciences: A Tutorial. https://doi.org/10.31219/osf.io/kwh7n. Wong, P. C. M., Parsons, L. M., Martinez, M., & Diehl, R. L. (2004). The Role of the Insular Cortex in Pitch Pattern Perception: The Effect of Linguistic Contexts. The Journal of Neuroscience, 24(41), 9153–9160.
Topic Areas: Speech Perception, Multilingualism