Native language governs interpretation of salient speech sound differences at 18 months

Abstract

One of the first steps infants take in learning their native language is to discover its set of speech-sound categories. This early development is shown when infants begin to lose the ability to differentiate some of the speech sounds their language does not use, while retaining or improving discrimination of language-relevant sounds. However, this aspect of early phonological tuning is not sufficient for language learning. Children must also discover which of the phonetic cues that are used in their language serve to signal lexical distinctions. Phonetic variation that is readily discriminable to all children may indicate two different words in one language but only one word in another. Here, we provide evidence that the language background of 1.5-year-olds affects their interpretation of phonetic variation in word learning, and we show that young children interpret salient phonetic variation in language-specific ways. Three experiments with a total of 104 children compared Dutch-and English-learning 18-month-olds' responses to novel words varying in vowel duration or vowel quality. Dutch learners interpreted vowel duration as lexically contrastive, but English learners did not, in keeping with properties of Dutch and English. Both groups performed equivalently when differentiating words varying in vowel quality. Thus, at one and a half years, children's phonological knowledge already guides their interpretation of salient phonetic variation. We argue that early phonological learning is not just a matter of maintaining the ability to distinguish language-relevant phonetic cues. Learning also requires phonological interpretation at appropriate levels of linguistic analysis.language acquisition ͉ lexical development ͉ phonology ͉ word learning I nfants begin to acquire their native language by learning phonetic categories (1, 2). At birth, infants seem to distinguish most of the phonetic contrasts used by the world's languages. However, over the first year, this ''universal'' capacity shifts to a language-specific pattern in which infants retain or improve categorization of native-language sounds but fail to discriminate many nonnative sounds. Children's failure to discriminate nonnative sound contrasts is actually advantageous for learning language, because it prevents children from misinterpreting within-category phonetic variation as indicating a linguistic distinction.However, whereas infants' phonetic category learning is of clear relevance to language acquisition, discrimination failure is not the only mechanism that is required for developing a native-language phonology that can correctly categorize words (3-5). Many phonetic properties of speech remain discriminable to infants even when the native language does not use these properties to distinguish words. For example, pitch variation is a salient phonetic property of speech but is not used systematically in English for marking different words (in contrast to ''tone'' languages, like Mandarin, in which syllables comprising the same phonetic segments have...

Development of perceptual sensitivity to extrinsic vowel duration in infants learning American English

“…It is also consistent with the recent finding that language-specific phonology influences the development of infants' speech perception (Mugitani et al, 2009). At first blush, our findings appear to contradict Dietrich et al (2007), in which English-learning 18-month-olds failed to link two novel objects with the two stimuli differing only in vowel duration. However, there is good reason to suspect that older infants are less likely to discriminate auditory patterns in a word-learning context than in a pure preference or discrimination task (Stager and Werker, 1997).…”

“…Recently, Dietrich et al (2007) found that Dutch and English learning 18-month-olds treat vowel duration differently in a word learning task. In Dutch, vowel duration is an important cue for differentiating the low vowels [Ä] and [ab], whereas in English, it is only a secondary cue to distinguish a tense from a lax vowel.…”

Semantics guide infants’ vowel learning: Computational and experimental evidence

“…Although it was initially hypothesized that infants learn sounds from contrastive meanings, i.e., minimal pairs (Werker & Tees, 1984), this idea was challenged by the finding that infants are sensitive to language-specific phonetic detail at an age at which they hardly know any words, let alone enough minimal pairs to allow for all contrasts (e.g., Caselli et al, 1995;Dietrich, Swingley, & Werker, 2007). Instead, current theories of first language acquisition argue that perceptual reorganization occurs mainly through bottom-up learning from speech input (e.g., Kuhl et al, 2008;Pierrehumbert, 2003;Werker & Curtin, 2005).…”

Dutch and English listeners’ interpretation of vowel duration

“…Also, Dutch orthography, in contrast to English, clearly marks durational oppositions, as in maan ("moon") and man ("man"), rules that are very familiar to literate Dutch adults. Finally, Dutch unlike English speakers have been reported to be reluctant to exaggerate the duration of short vowels to convey emphasis in child-directed speech (Dietrich et al, 2007). In most dialects of English vowel duration is not considered contrastive, though vowels vary in their "intrinsic" durations (House, 1961;Chomsky and Halle, 1968;Hillenbrand et al, 2000) and duration varies depending on context, as will be discussed in more detail below.…”