Audiovisual alignment of co-speech gestures to speech supports word learning in 2-year-olds

Analyses of caregiver-child communication suggest that an adult tends to highlight objects in a child's visual scene by moving them in a manner that is temporally aligned with the adult's speech productions. Here, we used the looking-while-listening paradigm to examine whether 25-month-olds use audiovisual temporal alignment to disambiguate and learn novel word-referent mappings in a difficult word-learning task. Videos of two equally interesting and animated novel objects were simultaneously presented to children, but the movement of only one of the objects was aligned with an accompanying object-labeling audio track. No social cues (e.g., pointing, eye gaze, touch) were available to the children because the speaker was edited out of the videos. Immediately afterward, toddlers were presented with still images of the two objects and asked to look at one or the other. Toddlers looked reliably longer to the labeled object, demonstrating their acquisition of the novel word-referent mapping. A control condition showed that children's performance was not solely due to the single unambiguous labeling that had occurred at experiment onset. We conclude that the temporal link between a speaker's utterances and the motion they imposed on the referent object helps toddlers to deduce a speaker's intended reference in a difficult word-learning scenario. In combination with our previous work, these findings suggest that intersensory redundancy is a source of information used by language users of all ages. That is, intersensory redundancy is not just a word-learning tool used by young infants.