This research investigates selectivity in word learning for bilingual infants. Previous work demonstrated that bilingual infants show greater openness to non-native language sounds in object labels than monolinguals (Hay et al., 2015; Singh, 2018). It remains unclear whether bilingual openness extends to nonspeech sounds. We presented 14- and 19-month-old bilinguals with object labels consisting of nonspeech tones. Monolinguals recently displayed learning of the same labels at 14 months, but not 19 months (Graf Estes et al., 2018). In contrast, bilinguals failed to learn the labels. We propose that hearing phonological variation across two languages helps bilinguals reject nonspeech word forms.

This experimental study examined bilingual (English and another noun-dominant language) and monolingual (English) preverbal (10.5-month-old) and postverbal (12.5-month-old) infants’ word-action mapping. Sixteen infants in each group were habituated to dynamic video-displays of novel word-action pairings during infant-controlled habituation. They received two words, /wem/ and /bæf/, spoken synchronously with an adult shaking or looming an object, and were tested with switched versus same word-action pairings. Results revealed that for the preverbal bilingual infants, word-action mapping is intensified relative to postverbal bilingual infants. For the postverbal bilingual infants, word-action mapping is attenuated and inversely correlated with noun learning. No such differences were observed in the monolingual infants. These findings illustrate a perceptual protraction prior to word production, and accelerated perceptual narrowing to nouns after word production in bilingual infants learning two noun-dominant languages.