Liquan Liu

Bilingual exposure influences infant VOT perception.

Linking the discrimination of voice onset time (VOT) in infancy with infant language background, we examine the perceptual changes of two VOT contrasts (/b/-/p/ and /p(h)/-/p/) by Dutch monolingual and bilingual infants from 8 to 15 months of age. Results showed that language exposure and language dominance had a strong impact on monolingual and bilingual infant VOT perceptual patterns. In addition, perceptual turbulence was found at 8-9 months for bilingual infants, and stabilized perception was presented for all infants from 11 months onwards. We thus report a general input-driven developmental VOT perception in both monolingual and bilingual infants, with perceptual turbulence for bilinguals in the second half of the first year of life.

Perception of tones by bilingual infants learning non-tone languages

This paper examines the ability of bilingual infants who were learning Dutch and another non-tone language to discriminate tonal contrasts. All infants from 5 to 18 months of age succeeded in discriminating a tonal contrast of Mandarin Chinese (Tone 1 versus Tone 4) and showed a U-shaped pattern when facing a less acoustically salient manipulated version (contracted) of the aforementioned contrast. Specifically, infants showed initial sensitivity to the contracted contrast during their early months, followed by a loss of sensitivity at the stage where tonal perceptual reorganization typically occurs, and a sensitivity rebound by the end of the first year after birth. Compared to a previous studying of ours testing monolingual Dutch infants (Liu & Kager, 2014), the discrimination patterns of bilingual infants revealed both similarities and differences. On one hand, as with monolinguals, non-tone-learning bilingual infants’ tonal perception presented plasticity influenced by contrast acoustic salience along the trajectory of perceptual reorganization; as well as a general U-shaped perceptual pattern when discriminating non-native tones. On the other hand, bilingual infants appeared to regain sensitivity to the contracted tonal contrast at an earlier age (11–12 months) in comparison with monolinguals infants (17–18 months). We provide several explanations, stemming from the simultaneous exposure to two languages, to account for the 6-month bilingual perceptual plasticity from linguistic and cognitive perspectives. The overall outcomes of the study offer insights into the infant perceptual reorganization and language development trajectory, expand on the differences between monolingual and bilingual language development, and broaden our understanding of the influence of bilingual exposure to the perception of non-native contrasts in infancy from linguistic and cognitive perspectives.

Perception of a native vowel contrast by Dutch monolingual and bilingual infants: A bilingual perceptual lead

Purpose: Facing previous mixed findings between monolingual and bilingual infants’ phonetic development during perceptual reorganization, the current study aims at examining the perceptual development of a native vowel contrast (/I/-/i/) by Dutch monolingual and bilingual infants. Design: We tested 390 Dutch monolingual and bilingual infants from 5 to 15 months of age through a visual habituation paradigm. Data and analysis: Mixed-effect model analyses were conducted within 320 infants, with infants’ log10 transformed looking time as the dependent variable, age (4-level) and language background (2-level) as the fixed factors, and participant and order (2-level) as the random factors. Conclusions: All infants show weak initial sensitivity to the contrast regardless of language background(s), and sensitivity improves with age. By the second half of the first year, infants discriminate the contrast, indicating the emergence of the relevant vowel categories. In addition, a perceptual lead is observed in bilingual infants, probably due to: 1) a perceptual transfer from the close-category counterpart of the other native language; 2) heightened acoustic sensitivity in bilingual infants given their rich linguistic experience; and 3) a general bilingual cognitive advantage. The influences of contrast salience and bilingualism on language development are discussed. Originality: Overall, these findings constitute an extension of existing work on vowel perception and display a novel acceleration effect for the bilingual infants in phonetic perception. In addition, we propose a novel heightened acoustic sensitivity hypothesis, arguing that bilingual infants may pay more attention to acoustic details in the input than their monolingual peers. Significance: The observed progressive phonetic discrimination pattern of the native contrast contributes to our knowledge in infant language development, and specifically perceptual reorganization patterns, in the first year after birth. The observed acceleration effect, along with its explanations, provides new insights into the influence of bilingualism and potential bilingual advantages in infancy.

Cross-domain correlation in pitch perception, the influence of native language

ABSTRACT The current study explores how language experience may shape the correlation between lexical tone and musical pitch perception. A two domains (music and lexical tone) by two languages (tone, Mandarin Chinese and non-tone, Dutch) design is adopted. Participants were tested on their discrimination of Mandarin Chinese lexical tones, Montreal Battery of Evaluation of Amusia (MBEA), and Musical Ear Test (MET). The Chinese listeners outperformed the Dutch listeners on both MBEA and MET, but had comparable accuracies for the lexical tone discrimination. Importantly, a significant cross-domain correlation was only observed for the Dutch listeners but not for the Chinese listeners. For tone language listeners, once lexical tones have been acquired, native listeners perceive them as phonological categories, and split them from other pitch variations that do not play a phonemic role. Non-tone language listeners, on the other hand, perceive both lexical tones and musical pitch on a psycho-acoustical basis, hence exhibit a unified perception of pitch across the two domains.

Is mommy talking to daddy or to me? Exploring parental estimates of child language exposure using the Multilingual Infant Language Questionnaire

ABSTRACT Language input is a key factor in bi-/multilingual research. It roots in the definition of bi-/multilingualism and influences infant cognitive development since and even before birth. The methods used to assess language exposure among bi-/multilingual infants vary across studies. This paper discusses the parental report patterns of the amount/degree of exposure to their children and provides an algorithm-based Multilingual Infant Language Questionnaire (MILQ) targeting the amount of hours and degree of exposure an infant is exposed to each language. In the MILQ, parental feedback between general language input (languages spoken in the environment an infant resides in) and direct language exposure (languages spoken directly to an infant) are differentiated. Comparing the results drawn from general and direct perspectives, parental estimates of their children’s exposure match the general but not direct language input condition. Implications of these results are discussed.

Monolingual and Bilingual Infants’ Ability to Use Non-native Tone for Word Learning Deteriorates by the Second Year After Birth

Previous studies reported a non-native word learning advantage for bilingual infants at around 18 months. We investigated developmental changes in infant interpretation of sounds that aid in object mapping. Dutch monolingual and bilingual (exposed to Dutch and a second non-tone-language) infants’ word learning ability was examined on two novel label–object pairings using syllables differing in Mandarin tones as labels (flat vs. falling). Infants aged 14–15 months, regardless of language backgrounds, were sensitive to violations in the label–objects pairings when lexical tones were switched compared to when they were the same as habituated. Conversely at 17–18 months, neither monolingual nor bilingual infants demonstrated learning. Linking with existing literature, infants’ ability to associate non-native tones with meanings may be related to tonal acoustic properties and/or perceptual assimilation to native prosodic categories. These findings provide new insights into the relation between infant tone perception, learning, and interpretative narrowing from a developmental perspective.

One Way or Another: Evidence for Perceptual Asymmetry in Pre-attentive Learning of Non-native Contrasts

Research investigating listeners’ neural sensitivity to speech sounds has largely focused on segmental features. We examined Australian English listeners’ perception and learning of a supra-segmental feature, pitch direction in a non-native tonal contrast, using a passive oddball paradigm and electroencephalography. The stimuli were two contours generated from naturally produced high-level and high-falling tones in Mandarin Chinese, differing only in pitch direction (Liu and Kager, 2014). While both contours had similar pitch onsets, the pitch offset of the falling contour was lower than that of the level one. The contrast was presented in two orientations (standard and deviant reversed) and tested in two blocks with the order of block presentation counterbalanced. Mismatch negativity (MMN) responses showed that listeners discriminated the non-native tonal contrast only in the second block, reflecting indications of learning through exposure during the first block. In addition, listeners showed a later MMN peak for their second block of test relative to listeners who did the same block first, suggesting linguistic (as opposed to acoustic) processing or a misapplication of perceptual strategies from the first to the second block. The results also showed a perceptual asymmetry for change in pitch direction: listeners who encountered a falling tone deviant in the first block had larger frontal MMN amplitudes than listeners who encountered a level tone deviant in the first block. The implications of our findings for second language speech and the developmental trajectory for tone perception are discussed.