Speaker variability augments phonological processing in early word learning

Abstract

Infants in the early stages of word learning have difficulty learning lexical neighbors (i.e., word pairs that differ by a single phoneme), despite the ability to discriminate the same contrast in a purely auditory task. While prior work has focused on top-down explanations for this failure (e.g. task demands, lexical competition), none has examined if bottom-up acoustic-phonetic factors play a role. We hypothesized that lexical neighbor learning could be improved by incorporating greater acoustic variability in the words being learned, as this may buttress still developing phonetic categories, and help infants identify the relevant contrastive dimension. Infants were exposed to pictures accompanied by labels spoken by either a single or multiple speakers. At test, infants in the single-speaker condition failed to recognize the difference between the two words, while infants who heard multiple speakers discriminated between them.

Studying individual differences in the social environment to better understand language learning and processing

“…Thus 14-month old infants fail at understanding that the nonsense words, puk and buk, refer to different objects if they were earlier exposed to productions of one of these words by only one speaker. In contrast, if exposed to the same number of tokens of this word, but from 18 different speakers, infants succeed at mapping those words to different objects, indicating that they have acquired the phonemic contrast between /p/ and /b/ (Rost and McMurray 2009). Similar results have also been found with adults acquiring a new phonological variety.…”

The Distribution of Talker Variability Impacts Infants’ Word Learning

“…Recent evidence from Rost and McMurray (2009; indicates that increasing variability in talker's voice during the habituation phase of the Switch procedure leads to more robust differentiation of similar-sounding words (/buk/ and /puk/) at 14 months. Whereas infants fail to differentiate newly learned minimal-pair words when both are spoken by a single talker, they succeed when the words are spoken by 18 different talkers.…”

Contributions of infant word learning to language development

“…Manipulations that enhance 14-month-olds' phonological processing of the words improve performance (e.g. Thiessen 2007;Rost & McMurray 2009), suggesting that children might learn the referents of pairs of similar-sounding words more readily if the words' forms were familiar.…”