Autistic individuals benefit from gestures during degraded speech comprehension

Meaningful gestures enhance degraded speech comprehension in neurotypical adults, but it is unknown whether this is the case for neurodivergent populations, such as autistic individuals. Previous research demonstrated atypical multisensory and speech-gesture integration in autistic individuals, suggesting that integrating speech and gestures may be more challenging and less beneficial for speech comprehension in adverse listening conditions in comparison to neurotypicals. Conversely, autistic individuals could also benefit from additional cues to comprehend speech in noise, as they encounter difficulties in filtering relevant information from noise. We here investigated whether gestural enhancement of degraded speech comprehension differs for neurotypical ( n = 40, mean age = 24.1) compared to autistic (n = 40, mean age = 26.8) adults. Participants watched videos of an actress uttering a Dutch action verb in clear or degraded speech accompanied with or without a gesture, and completed a free-recall task. Gestural enhancement was observed for both autistic and neurotypical individuals, and did not differ between groups. In contrast to previous literature, our results demonstrate that autistic individuals do benefit from gestures during degraded speech comprehension, similar to neurotypicals. These findings provide relevant insights to improve communication practices with autistic individuals and to develop new interventions for 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.