Abstract
In face-to-face contexts, discourse is accompanied by various cues, like gestures and mouth movements. Here, we asked whether the presence of gestures and mouth movements benefits discourse comprehension under clear and challenging listening conditions and, if so, whether this multimodal benefit depends on the communicative environment in which interlocutors are situated. In two online experiments, participants watched videoclips of a speaker telling stories, and they answered yes-no questions about the content of each story. The speaker in the videos was spontaneously gesturing (or kept her hands still) and was wearing a surgical mask (or had her lips visible). The experiments differed in the communicative environment. In Experiment 1, the speaker narrated stories in silence, whereas the listener (participants) heard them in clear or degraded speech conditions (analogous to watching the news on TV in a quiet or noisy café). In Experiment 2, the speaker narrated the stories once in silence and once while listening to background noise, and the listener heard them in clear or degraded speech condition, respectively (analogous to listening to a friend in a quiet or noisy café). Across the experiments, we found that cospeech gestures facilitated discourse comprehension regardless of the listening conditions or the presence of a mask. In contrast, mouth movements were primarily helpful in challenging listening conditions. These findings indicate that both cues matter to listeners but to a different extent. Moreover, we found that the multimodal benefit to comprehension was similar regardless of the communicative environment. Thus, this study demonstrates the importance of both cospeech gestures and mouth movements to discourse comprehension, offering insights into the dynamic interplay between these cues under different communicative environments. (PsycInfo Database Record (c) 2025 APA, all rights reserved).