Multisensory Integration of Naturalistic Speech and Gestures in Autistic Adults

Seeing the speaker facilitates auditory speech comprehension through audio-visual integration. This is especially the case in challenging listening conditions, such as in real-life social environments. Autism has been associated with atypicalities in integrating audio-visual information, potentially underlying social difficulties in this population. The present study investigated multisensory integration (MSI) in speech processing among autistic (N=35) and neurotypical (N=35) adults. Participants performed a speech-in-noise task in a realistic multispeaker social scenario with audio-visual, auditory, or visual trials while their brain activity was recorded using EEG. The neurotypical group demonstrated a non-linear audio-visual interaction in alpha suppression, whereas the autistic group showed merely additive processing of these same inputs. Despite these differences in neural correlates, both groups achieved similar behavioural audio-visual facilitation outcomes. These findings suggest that although autistic and neurotypical brains might process multisensory cues differently, they achieve comparable benefits from audio-visual speech. These results contribute to the growing body of literature on MSI atypicalities in autism.