The development of tone discrimination in infancy: Evidence from a cross-linguistic, multi-lab report.

We report the findings of a multi-language and multi-lab investigation of young infants' ability to discriminate lexical tones as a function of their native language, age and language experience, as well as of tone properties. Given the high prevalence of lexical tones across human languages, understanding lexical tone acquisition is fundamental for comprehensive theories of language learning. While there are some similarities between the developmental course of lexical tone perception and that of vowels and consonants, findings for lexical tones tend to vary greatly across different laboratories. To reconcile these differences and to assess the developmental trajectory of native and non-native perception of tone contrasts, this study employed a single experimental paradigm with the same two pairs of Cantonese tone contrasts (perceptually similar vs. distinct) across 13 laboratories in Asia-Pacific, Europe and North-America testing 5-, 10- and 17-month-old monolingual (tone, pitch-accent, non-tone) and bilingual (tone/non-tone, non-tone/non-tone) infants. Across the age range and language backgrounds, infants who were not exposed to Cantonese showed robust discrimination of the two non-native lexical tone contrasts. Contrary to this overall finding, the statistical model assessing native discrimination by Cantonese-learning infants failed to yield significant effects. These findings indicate that lexical tone sensitivity is maintained from 5 to 17 months in infants acquiring tone and non-tone languages, challenging the generalisability of the existing theoretical accounts of perceptual narrowing in the first months of life. RESEARCH HIGHLIGHTS: This is a multi-language and multi-lab investigation of young infants' ability to discriminate lexical tones. This study included data from 13 laboratories testing 5-, 10-, and 17-month-old monolingual (tone, pitch-accent, non-tone) and bilingual (tone/non-tone, non-tone/non-tone) infants. Overall, infants discriminated a perceptually similar and a distinct non-native tone contrast, although there was no evidence of a native tone-language advantage in discrimination. These results demonstrate maintenance of tone discrimination throughout development.

Tonal interference in word learning? A comparison of Cantonese and French.

Most languages of the world use lexical tones to contrast words. Thus, understanding how individuals process tones when learning new words is fundamental for a better understanding of the mechanisms underlying word learning. The current study asked how tonal information is integrated during word learning. We investigated whether variability in tonal information during learning can interfere with the learning of new words and whether this is language and age dependent. Cantonese- and French-learning 30-month-olds (N = 97) and Cantonese- and French-speaking adults (N = 50) were tested with an eye-tracking task on their ability to learn phonetically different pairs of novel words in two learning conditions: a 1-tone condition in which each object was named with a single label and a 3-tone condition in which each object was named with three different labels varying in tone. We predicted learning in all groups in the 1-tone condition. For the 3-tone condition, because tones are part of the phonological system of Cantonese but not of French, we expected the Cantonese groups to either fail (toddlers) or show lower performance than in the 1-tone condition (adults), whereas the French groups might show less sensitivity to this manipulation. The results show that all participants learned in the 1-tone condition and were sensitive to tone variation to some extent. Learning in the 3-tone condition was impeded in both groups of toddlers. We argue that tonal interference in word learning likely comes from the phonological level in the Cantonese groups and from the acoustic level in the French groups.