Whole-body synchronization in autistic adults.

INTRODUCTION: A characteristic feature of autistic individuals is deviations in nonverbal behavior during social interactions, evident in altered synchronization. In non-autistic individuals, increased synchronization adversely affects the capacity for emotional self-regulation. Yet, synchronization in autistic individuals has primarily been examined in conversational contexts. METHODS: In this study, 33 autistic and 33 non-autistic adults performed a dyadic movement task. Participants were asked to "have a conversation without words" using only improvised movements. Using an inertial sensor-based motion capture system, we investigated interpersonal synchronization. RESULTS: Our findings indicated greater synchronization in autistic dyads than in non-autistic dyads. Mixed dyads did not differ from either autistic or non-autistic dyad. Across all three dyad types, the task was not associated with reliable observed changes in emotional self-regulation, positive affect, or negative affect, and baseline-adjusted post-task outcomes were not reliably associated with interpersonal synchronization. However, it is important to note our small sample size, which limits the robustness and generalizability of the results. DISCUSSION: We discuss our findings in relation to the task demands. Whole-body synchronization played a crucial role in our study, unlike in previous studies of conversational settings. Consequently, our task relied less on language, familiarity with social interaction tasks, and eye contact, all of which are aspects that autistic individuals often find challenging. Our findings contribute to the ongoing debate on interpersonal synchronization in autism spectrum condition by extending previous studies on conversational contexts to whole-body movement. The data can be combined with future datasets to create larger samples and provide a more nuanced understanding about synchronization in autism spectrum condition.