Replacing the Body in Embodiment: The Relationship Between Avatars and Interoception in Virtual Reality

This thesis examines the relationship between an individual's sense of embodiment towards an avatar and the processing and awareness of internal body signals (body awareness) in virtual reality (VR) in the context of mind-body interventions. To do so, I present a systematic literature review, a user experience evaluation of an avatar embodiment system, and a series of five experiments that systematically assess the effects of discrepancy between the user's corporeal body and their avatar. The systematic literature review gives insights into the current landscape of VR mind-body interventions and combines them with a framework for designing and evaluating VR-based intervention modules. This framework forms the basis for the design of my empirical work. The user experience evaluation study presents the technical basis of my research. It maps the general processes for creating photorealistic personalized avatars. Further, it presents an embodiment system to control and animate these avatars in VR and a general experimental procedure before and within VR, ensuring a positive experience. The first two experiments on the sense of embodiment towards an avatar and body awareness examine the relationship between the two variables and the effect of VR in a close-to-reality scenario on both of them. The other three experiments examine the effects of discrepancy between the user's corporeal body and their avatar. They target non-similar avatar appearance, mid-experience perspective changes, avatar visibility, and virtual out-of-body experiences. The empirical studies of my thesis revealed some key findings: 1. Users experienced a reduced sense of embodiment towards their avatar compared to their corporeal body. 2. Embodying an avatar was accompanied by a reduced body awareness. 3. The sense of embodiment was positively related to body awareness on several dimensions. Some of these served as mediators between the effects of VR and avatar discrepancy on body awareness. 4. However, increasing the discrepancy between the avatar and the user's corporeal body did not necessarily have a negative effect on body awareness. Rather, embodying non-personalized avatars and/or changing into an outside perspective increased body awareness compared to embodying a personalized avatar from a first-person perspective. The presented research provides insight into the interplay of avatar presentation, sense of embodiment, and body awareness in the context of VR mind-body interventions. From the results, I draw conclusions about the application in therapeutic and non-therapeutic settings. I discuss these results in the context of psychological embodiment research and the role of the body in mental health. Finally, I present a set of outlines for future work towards integrating body awareness in virtual mind-body interventions.