Can bilingual children turn one language off? Evidence from perceptual switching

• Can bilingual children interpret tones flexibly based on language cues? 3–5 year-old children were tested on tone sensitivity in English and Mandarin.
• Children were tasked with learning new words in English and Mandarin.
• At 3–4 years, children could not switch interpretation of tone between languages.
• At 4–5 years of age, children benefited from phonotactic cues to language.
• Perceptual switching is dependent on phonological support at 5 years of age.

Bilinguals have the sole option of conversing in one language in spite of knowing two languages. The question of how bilinguals alternate between their two languages, activating and deactivating one language, is not well understood. In the current study, we investigated the development of this process by researching bilingual children’s abilities to selectively integrate lexical tone based on its relevance in the language being used. In particular, the current study sought to determine the effects of global conversation-level cues versus local (within-word phonotactic) cues on children’s tone integration in newly learned words. Words were taught to children via a conversational narrative, and word recognition was investigated using the intermodal preferential-looking paradigm. Children were tested on recognition of words with stimuli that were either matched or mismatched in tone in both English and Mandarin conversations. Results demonstrated that 3- to 4-year-olds did not adapt their interpretation of lexical tone changes to the language being spoken. In contrast, 4- to 5-year-olds were able to do so when supported by informative within-word cues. Results suggest that preschool children are capable of selectively activating a single language given word-internal cues to language.