Eyes can tell. Attention to the eyes and the mouth during audiovisual vowel processing in monolingual and bilingual infants

After 6 months of age monolingual infants look more to the mouth of a speaker when there is a mismatch (as opposed to match) between heard and (visually) articulated native consonants. Here, we examined whether monolingual and bilingual infants increase their attention to speakers’ mouth when processing vowels. We compared 4.5- and 8-month-old monolingual and bilingual infants’ attention to the eyes and the mouth while presented with native vowels in audiovisual match and mismatch conditions. We observed that 4.5-month-old monolingual and bilingual infants detect the AV mismatch by increasing their attention to the eyes, not to the mouth – as has been previously observed for consonants. However, by 8 months of age monolingual and bilingual infants’ attention to the eyes and the mouth is not affected by audiovisual disruption. Our findings suggest that audiovisual vowel and consonant processing differ during the first year of life, and that the specific type of linguistic experience does not modulate selective attention to the mouth or the eyes during vowel processing.