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

Abstract

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.

The Use of Pitch Accent in Word–Object Association by Monolingual Japanese Infants

“…For example, Hay and colleagues tested 14‐, 17‐ and 19‐month‐old monolingual English‐learning infants with word–object mappings differing by Mandarin lexical tone contrasts (Hay et al., ). Work within the habituation Switch paradigm revealed that young 14‐month‐old infants succeeded in the task, whereas older, 17‐ and 19‐month‐old infants failed (see also Liu & Kager, , claiming a similar perceptual narrowing process for tone in monolingual Dutch infants). Singh and colleagues employed a visual choice paradigm to address a similar question (Singh et al., ).…”

“…Surprisingly, native tone‐language learners failed to use tones to learn words at around 12–13 months of age (Singh et al., ) although English‐ or Dutch‐learning 14‐month‐old infants, for whom tone distinctions are non‐native, succeeded in the task (Hay et al., ; Liu & Kager, ). What makes non‐native infants at this age outperform native infants?…”

“…In other words, prosodic features may not continue to be robust cues for word recognition through the lifespan. As described above, perceptual narrowing in word learning takes place between 17 and 19 months of age in non‐tone‐language learners (Hay et al., ; Liu & Kager, ). Likewise, English‐learning 2.5‐year‐olds and adults do not respond differently to novel words that contrast in pitch pattern alone (Quam & Swingley, ), and children are less sensitive to pitch mispronunciations of words than adults (Quam & Swingley, ).…”

“…Traditionally, most of the research on early word–object association has focused on how infants learn words using segmental features. However, some recent studies have started to shed light on word learning with regard to suprasegmental features such as stress, accent, and lexical tones (e.g., Burnham, Singh, Mattock, Woo, & Kalashnikova, ; Curtin, , ; Curtin, Campbell, & Hufnagle, ; Graf Estes & Hay, ; Hay, Graf Estes, Wang, & Saffran, ; Liu & Kager, ; Singh, Hui, Chan, & Golinkoff, ; Singh, Poh, & Fu, ; see Singh & Fu, for review). In line with these studies, the present work explores the role of suprasegmental features in early lexical acquisition by testing monolingual Japanese infants’ ability to use Japanese lexical pitch accent in word–object associative learning.…”

“…This fact allows us to home in on the contribution of pitch alone to word learning, and to refine our understanding of the interactions between word learning and suprasegmental features explored in existing research. In addition, most studies involving word–object pairing with lexical tone often focus on non‐native or bilingual listeners (e.g., Graf Estes & Hay, ; Hay et al., ; Liu & Kager, ). Although data have recently accumulated concerning native language listeners as well, the current study will contribute to revealing how infants who must learn lexical pitch distinctions in their native language attend to pitch information during early word learning.…”