Infants Do Not Reliably Track When Bilingual Speakers Switch Languages

It is a widely held belief that bilingual infants benefit from hearing each of their languages spoken by different people, as speakers could serve as a cue for separating the two languages. However, it is not yet known whether infants reliably attend to speaker-specific language use. In four experiments using looking time measures, we asked whether monolingual and bilingual infants in the U.S. could learn pairings between speakers and languages. Infants were first familiarized with two speakers, each using a different language. Then, after infants habituated, the two speakers switched languages, and we measured whether infants showed increased interest in hearing the speakers use a different language. Across all four studies, infants did not show reliable evidence that they detected a change in the language used by individual speakers, suggesting that speaker-language associations may not be a salient source of information for infants.