Multimodal Synchrony Dynamics of Emotional Contagion During Mother-Child interactions in Autism

<title>Abstract</title> Emotional contagion—the unconscious process of sharing others’ emotions—is foundational to early social development, yet its mechanisms in autistic children remain unclear. Here, we employed a naturalistic mother-child interaction paradigm combined with multimodal measurements (facial expression tracking, heart rate monitoring, and functional near-infrared spectroscopy hyperscanning) to investigate happy and sad emotional contagion in preschool autistic and nonautistic children during interactions with their mothers. The results first showed that autistic children exhibit valence-specific dissociation in emotional contagion. Specifically, during sad emotional contagion, autistic children displayed stronger facial expression intensity but lower imitation precision and facial synchrony compared to their nonautistic peers. They also had lower heart rates, enhanced functional connectivity between the right Primary Somatosensory Cortex (rPSC) and right Premotor Cortex (rPMC), and higher inter-brain synchrony between the maternal inferior parietal lobule (IPL) and the child’s Primary Somatosensory Cortex (PSC). In contrast, during happy emotional contagion, autistic children’s behavioral responses were comparable to those of nonautistic children, but they exhibited distinct neural patterns (e.g., reduced sensorimotor connectivity).Machine learning analyses confirmed that integrating facial, intra-brain, and inter-brain data achieves a classification accuracy of 94.74%, outperforming unimodal measures and highlighting the systemic nature of differences in emotional contagion among autistic children. These findings reveal valence-specific dissociation and multi-level synchrony disruption in autistic children’s emotional contagion, as well as bidirectional neural adaptation in mother-child dyads. Collectively, this study found the unique neurobehavioral signature of core neurointegration differences in emotional contagion, and highlighted the necessity of interactive, multimodal approaches to unravel the complexity of social interaction in autism.