Vocal smile is recognized but not embodied in autistic adults.

Autism spectrum disorder (ASD) is frequently characterized by atypical responses to emotional prosody and a lack of response to social smiles. This study examined whether autistic adults show motor resonance to vocal smiles, as reflected in facial muscle activity, when listening to emotional vocal cues. Facial electromyography was recorded while autistic and neurotypical adults listened to sentences spoken with smiling or neutral prosody and judged their emotional content. Both groups accurately recognized smiling prosody, indicating intact perceptual abilities in autism. However, only neurotypical participants showed enhanced zygomaticus activation in response to smiling voices, whereas autistic participants did not modulate facial muscle activity despite correct recognition. This dissociation between identification and motor reactivity suggests that autistic individuals can accurately recognize vocal emotions, but these are not embodied. These findings provide insights into the mechanisms that shape social engagement in ASD and may inform therapeutic approaches targeting emotional embodiment.