L2 difficulties in the perception of Mandarin tones: Phonological universals or domain-general aptitude?

Abstract What makes lexical tones challenging for second language (L2) learners? Several recent studies suggest that two phonological universals, the Obligatory Contour Principle and the Tonal Markedness Scale, may constrain the L2 acquisition of Mandarin lexical tones, regardless of learners’ first language. We assessed the role of these universals in L2 tonal acquisition by learners from a non-tonal background (L1 Portuguese). We implemented a perceptual testing protocol, which contained a number of methodological and analytical improvements relative to previous studies, including the use of Bayesian mixed-effects models to assess evidence for null hypotheses. The results provided evidence for the null effects of both phonological universals. Instead, a clear determinant of tonal identification accuracy was the participants’ pitch acuity, suggesting that domain-general auditory processing underlies the learning of L2 phonological categories. All materials, data and code are publicly available in the OSF repository at https://osf.io/ezadw .