“What works, for whom”: Individual differences in presence, embodiment, and engagement, and their impact on Virtual Reality intervention effects

Background. Virtual Reality (VR) is increasingly utilized for interventions aimed at mental health and changing behavior. VR enables users to experience presence in the virtual environment, can generate an illusion of virtual body ownership, and triggers engagement with the task at hand. We examined whether presence, embodiment, and engagement predicted and moderated intervention effects. Moreover, we examined to what extent presence, embodiment, and engagement are stable versus fluctuating individual characteristics. Method. We used data from a randomized controlled trial (n = 106) in which the effectiveness of a VR intervention, “FutureU”, was tested. First, we conducted moderation analyses to study the direct effect and interaction effect of presence, embodiment, and engagement on the intervention outcome, i.e., vividness of the future self. Second, we conducted repeated-measures ANOVAs and bifactor models to analyze presence, embodiment and engagement’s stable versus fluctuating nature. Results. Presence and engagement positively predicted vividness of the future self. Additionally, both higher levels of presence and of engagement were related to stronger increases in vividness of the future self. Moreover, presence, embodiment, and engagement appeared stable over the course of the three intervention sessions. Conclusion. This study underscores the importance of presence and engagement in enhancing intervention effects within VR interventions, and highlights that individual differences in these constructs can explain variations in intervention outcomes. Importantly, the stability of presence, embodiment, and engagement over time indicates that these are stable user-characteristics rather than fluctuating states. Implications for practice are discussed.