This study advances the design of timing-sensitive, full-body interactive experiences supporting both collaboration and individual agency in children’s group play. We investigate how temporal structuring within an improved version of a full-body interactive system influences behavioral and perceived synchrony among children aged 9–10. Prior research has often focused on dyads, required human facilitation, or neglected relationship between perceived and actual synchrony. Addressing these gaps, we conducted a multi-user study comparing synchronous and asynchronous interaction modes using system-logged behavioral data and self-reports. Results demonstrate the synchronous condition fosters higher user performance, tighter temporal coordination, and stronger perceptions of shared movement. In contrast, the asynchronous mode effectively disrupts unintended coordination, showing how timing design shapes interaction dynamics. Notably, identical movements are perceived as less uniform without temporal alignment. These findings highlight the potential of embodied systems to scaffold or inhibit synchrony through intentional design, supporting richer social engagement and inclusive group play.

This study investigates how interpersonal synchrony (IPS) in full-body interactive Mixed Reality (MR) environments can shape children's prosocial behavior. We introduce DragonIce 2.0, a two-part MR game designed to induce synchronous or asynchronous group activity and assess their impact on prosocial behavior. To examine changes in affiliation (team belonging and peer liking) and collaboration (overt joint actions), we conducted a comparative study with children aged 9-10, using both system logs and self-report measures. The results highlight the importance of context, task structure, and perceived coordination in shaping social outcomes, offering insights into how interaction dynamics shape social engagement in immersive settings. This work contributes a novel approach for studying prosociality in ecologically valid, technology-mediated settings by combining playful, immersive interaction with controlled manipulation of group synchrony. Our findings inform the design of inclusive MR experiences that support social connection, collaboration, and group engagement among children.

Interpersonal Synchrony (IPS), the temporal coordination of actions between individuals, plays a crucial role in fostering social interactions, emotion regulation, and communication.While previous research has explored IPS in dyadic settings, little is known about how it can be supported in multi-user full-body interactive environments, especially for neurodivergent populations.This study presents an iterative design investigation of DragonIce, a full-body interactive experience aimed at promoting IPS among children on the Autism Spectrum (AS).Building on findings from a prior study involving 12 male students with autism, we implemented and tested two targeted interaction design modifications: (1) enhanced visual feedback and (2) the introduction of a hand-held object.The results revealed a significant improvement in behavioral synchrony following refinements and a positive trend in perceived synchrony and user experience, highlighting how specific interaction design elements shape user experience and perceived synchrony in groupbased settings.This work contributes to creating knowledge on how interaction design can be strategically employed to foster IPS, offering new directions for inclusive and socially supportive full-body experiences for neurodivergent children.