Autistic individuals benefit from gestures during degraded speech comprehension.

Lay abstract: Our study explored how meaningful hand gestures, alongside spoken words, can help autistic individuals to understand speech, especially when the speech quality is poor, such as when there is a lot of noise around. Previous research has suggested that meaningful hand gestures might be processed differently in autistic individuals, and we therefore expected that these hand gestures might aid them less in understanding speech in adverse listening conditions than for non-autistic people. To this end, we asked participants to watch and listen to videos of a woman uttering a Dutch action verb. In these videos, she either made a meaningful gesture while speaking, or not, and speech was clear, or noisy. The task for participants was to identify the verb in the videos. Contrary to what we expected, we found that both autistic and non-autistic individuals use meaningful information from hand gestures when understanding unclear speech. This means that gestural information can aid in communication, especially when communicative settings are suboptimal.