Higher or lower? Interpersonal behavioral and neural synchronization of movement imitation in autistic children

How well autistic children can imitate movements and how their brain activity synchronizes with the person they are imitating have been understudied. The current study adopted functional near‐infrared spectroscopy (fNIRS) hyperscanning and employed a task involving real interactions involving meaningful and meaningless movement imitation to explore the fundamental nature of imitation as a dynamic and interactive process. Experiment 1 explored meaningful and meaningless gesture imitation. The results revealed that autistic children exhibited lower imitation accuracy and behavioral synchrony than non‐autistic children when imitating both meaningful and meaningless gestures. Specifically, compared to non‐autistic children, autistic children displayed significantly higher interpersonal neural synchronization (INS) in the right inferior parietal lobule (r‐IPL) (channel 12) when imitating meaningful gestures but lower INS when imitating meaningless gestures. Experiment 2 further investigated the imitation of four types of meaningless movements (orofacial movements, transitive movements, limb movements, and gestures). The results revealed that across all four movement types, autistic children exhibited significantly lower imitation accuracy, behavioral synchrony, and INS in the r‐IPL (channel 12) than non‐autistic children. This study is the first to identify INS as a biomarker of movement imitation difficulties in autistic individuals. Furthermore, an intra‐ and interindividual imitation mechanism model was proposed to explain the underlying causes of movement imitation difficulties in autistic individuals. Lay Summary This study investigated how well autistic children can imitate movements and how their brain activity synchronizes with the person they are imitating. We found that autistic children have difficulty imitating both meaningful gestures and other meaningless movements. However, when imitating meaningful gestures, they show higher brain synchronization than non‐autistic children. On the other hand, their brain synchronization is lower when imitating meaningless movements, unlike that of non‐autistic children. Understanding these differences in brain synchronization can help us develop specific approaches to help children with autism improve their imitation skills.