Here's not looking at you, kid! Unaddressed recipients benefit from co-speech gestures when speech processing suffers

In human face-to-face communication, language comprehension is a multi-modal, situated activity. However, little is known about how we combine information from these different modalities, and how perceived communicative intentions, often signaled through visual signals, such as eye gaze, may influence this processing. We address this question by simulating a triadic communication context in which a speaker alternated her gaze between two different recipients. Participants thus viewed speech-only or speech+gesture object-related utterances when being addressed (direct gaze) or unaddressed (averted gaze). Two object images followed each message and participants’ task was to choose the object that matched the message. Unaddressed recipients responded significantly slower than addressees for speech-only utterances. However, perceiving the same speech accompanied by gestures sped them up to a level identical to that of addressees. That is, when speech processing suffers due to not being addressed, gesture processing remains intact and enhances the comprehension of a speaker’s message.