Early audiovisual language discrimination: Monolingual and bilingual infants’ differences in language switch detection

Successful language learning in bilinguals requires differentiation of two language systems. Capacity to discriminate rhythmically close languages has been reported in 4-month-olds using auditory-only stimuli. This research offers a novel perspective on early language discrimination using audiovisual material. Monolingual and bilingual infants were first habituated to a face talking in the participants' native language (or the more frequent language in bilingual contexts) and then tested on two successive language switches by the same speaker, with a close and a distant language. Code-switching exposure was indexed from parental questionnaires. Results revealed that while monolinguals could detect both the close- and distant-language switch, bilinguals only reacted to the distant language, regardless of home code-switching experience. In the temporal dimension, the analyses showed that language-switch detection required at least 10 seconds, suggesting that the audiovisual presentation (here the same speaker switching languages) slowed down or even hindered the language-switch detection. These results suggest that detection of a multimodal close-language switch is a challenging task, especially for bilingual infants exposed to phonologically and rhythmically close-languages. The current research sets the ground for further studies exploring the role of indexical cues and selective attention processes on language-switch detection.