Abstract
Interpersonal synchrony (IPS), the temporal alignment of behaviors between individuals, fosters social bonding, cooperation, and sharing in children. These prosocial outcomes make IPS a promising mechanism to support social inclusion and psychological well-being, particularly in therapeutic and educational contexts where strengthening peer interaction is essential. However, most IPS interventions rely on static dyadic tasks that lack playfulness and ecological validity, limiting their generalization to real-world environments. Advances in Mixed Reality (MR) offer new possibilities for designing more natural and embodied IPS experiences. Nevertheless, it remains unclear which specific design elements are most effective in eliciting synchrony that fosters prosocial outcomes in group-based settings. This study introduces The Moving Mandala, a playful Mixed Reality experience designed to foster real-time synchrony among four children (ages 8-10) through audiovisual cues and embodied interaction. In a between-subjects study with 268 children, participants were randomly assigned to one of four conditions: "no prior movement" (Baseline), "asynchronous and non-rhythmic ambient music" (Control), "synchronous and rhythmic music" (Experimental 1), and "synchronous and non-rhythmic ambient music" (Experimental 2). The study tested: (i) whether rhythmic auditory stimuli enhance IPS compared to non-rhythmic ambient sound, and (ii) whether synchronous movements facilitate prosocial behavior and social bonding compared to asynchronous and no prior (baseline) movements. Results showed that rhythmic music significantly improved synchrony performance, confirming its role as a temporal scaffold. However, no significant differences in prosocial behavior or social bonding were found between conditions. Design choices such as limited mutual dependency and high cognitive load may have reduced the salience of interpersonal cues. These findings highlight both the potential and challenges of using MR to promote synchrony-based social outcomes. By identifying key design elements, this work contributes to the development of engaging socially supportive MR interventions for children, with potential applications in therapeutic, educational, and rehabilitative contexts.