Self-Resemblance and Activity-Aware Responsiveness in XR Companions: Effects on Relational Openness and Reflection

As virtual companions increasingly populate extended reality (XR) environments, they are evolving from simple interactive interfaces into socially co-present entities that accompany users during everyday activities. This shift raises broader questions about how users' immediate relational perceptions toward digital agents can emerge in physically situated XR interaction. Prior research in psychology suggests that people may become more willing to disclose personal thoughts and emotions when relational closeness is perceived and when conversational partners demonstrate awareness of their behaviors or experiences. These findings imply that both relational identification and behavioral responsiveness may encourage users to move from simple expression toward more personally open interaction. In XR environments, such relational cues may be conveyed through how companions embody identity-related signals and how they perceive and respond to users' ongoing actions. To address this gap, we introduce a modular XR companion framework that independently manipulates two design dimensions: self-resemblance and activity-aware responsiveness. We evaluate these dimensions within a physical-virtual expressive interaction context using LEGO flower arrangement, where users' affective states are naturally externalized through open-ended physical construction. Our findings show that self-resemblance was associated with higher self-reported disclosure, social intimacy, and social connectedness, while activity-aware responsiveness primarily supported self-reflection and longer interaction. This work reframes XR companion design from enhancing presence to supporting immediate relational openness and provides design insights for identity-reflective and activity-contingent interaction in physical-virtual environments.