Lip reading could be a vital skill for language learners of all ages.

In a new study of monolingual and bilingual infants, Northeastern University professor David Lewkowicz and colleagues found that babies do the same, shifting their gaze to a speaker’s lips when they hear unfamiliar languages. But babies raised in bilingual households spend significantly more time studying the mouth than their monolingual counterparts—which suggests that lip reading could be a vital skill for language learners of all ages.