Can infants, in the very first stages of word learning, use their perceptual sensitivity to the phonetics of speech while learning words? Research to date suggests that infants of 14 months cannot learn two similar sounding words unless there is substantial contextual support. The current experiment advances our understanding of this failure by testing whether the source of infants' difficulty lies in the learning or testing phase. Infants were taught to associate two similar sounding words with two different objects, and tested using a visual choice method rather than the standard Switch task. The results reveal that 14-month-olds are capable of learning and mapping two similar sounding labels; they can apply phonetic detail in new words. The findings are discussed in relation to infants' concurrent failure, and the developmental transition to success, in the Switch task.

The development of native language phonetic representations in bilingual infants was compared to that of monolingual infants. Infants (ages 6–8, 10–12, and 14–20 months) from English–French or English-only environments were tested on their ability to discriminate a French and an English voice onset time distinction. Although 6- to 8-month-olds responded similarly irrespective of language environment, by 10–12 months both groups of infants displayed language-specific perceptual abilities: the monolinguals demonstrated realignment to the native English boundary whereas the bilinguals began discriminating both native boundaries. This suggests that infants exposed to two languages from birth are equipped to phonetically process each as a native language and the development of phonetic representation is neither delayed nor compromised by additional languages.

No abstract

Infant phonetic perception reorganizes in accordance with the native language by 10 months of age. One mechanism that may underlie this perceptual change is distributional learning, a statistical analysis of the distributional frequency of speech sounds. Previous distributional learning studies have tested infants of 6–8 months, an age at which native phonetic categories have not yet developed. Here, three experiments test infants of 10 months to help illuminate perceptual ability following perceptual reorganization. English‐learning infants did not change discrimination in response to nonnative speech sound distributions from either a voicing distinction (Experiment 1) or a place‐of‐articulation distinction (Experiment 2). In Experiment 3, familiarization to the place‐of‐articulation distinction was doubled to increase the amount of exposure, and in this case infants began discriminating the sounds. These results extend the processes of distributional learning to a new phonetic contrast, and reveal that at 10 months of age, distributional phonetic learning remains effective, but is more difficult than before perceptual reorganization.

Infants begin life ready to learn any of the world’s languages, but they quickly become speech-perception experts in their native language. Although this phenomenon has been well described, the mechanisms leading to native-language-listening expertise have not. In this article, we provide an in-depth review of one learning mechanism: distributional learning (DL), which has been shown to be important in phonetic category learning. DL is a domain-general statistical learning mechanism that involves tracking the relative frequency of phonetic tokens in speech input. Although DL is powerful, recent research has identified limitations to it as well. We conclude with a discussion of possible supplementary phonetic-learning mechanisms, which focuses on the surrounding context in which infants hear phonetic tokens and how it can augment DL and highlight important linguistic differences between perceptually similar stimuli.