Marie Luisa Fiedler, M.Sc.

Abstract: This paper presents the first systematic investigation of how congruence in visual self-representation influences self-perception and behavior. We span a continuum from the physical self through avatars with graded self-similarity to clearly dissimilar avatars in virtual reality (VR). In a 1x4 within-user study, participants completed movement and quiz tasks in either physical reality or a digital twin environment in VR, where they embodied one of three avatars: a photorealistic self-similar avatar, a dissimilar same-gender avatar, or a dissimilar opposite-gender avatar. Subjective measures included presence, sense of embodiment, self-identification, and perceived change, and were complemented by an objective movement metric of behavioral change. Compared to physical reality, VR, even with a self-similar avatar, produced lower presence, a weaker sense of embodiment, and reduced self-identification, revealing a persistent gap in visual congruence. Within VR, self-similar avatars enhanced body ownership, self-location, and self-identification relative to dissimilar avatars. Conversely, dissimilar avatars produced measurable behavioral changes compared with self-similar ones. Gender cues, however, had little impact in gender-neutral tasks. Overall, the findings show that photorealistic self-similar avatars reinforce embodiment and self-identification. However, VR still falls short of achieving congruence with physical reality, underscoring key challenges for avatar realism and ecological validity.

Abstract: Integrated Virtual Reality (IVR) systems are central to avatar-mediated use cases in Virtual Reality (VR), reconstructing users' movements on avatars. They differ primarily in their tracking architectures, which determine how completely and accurately users' movements are captured and reconstructed on avatars. Many current IVR systems reduce user-worn hardware, trading reconstruction accuracy against cost and setup complexity, yet their impact on user experience and task performance across use cases remains underexplored. We compared three reduced user-worn IVR systems. Each system has distinct technical approaches: (1) Captury (markerless outside-in optical tracking), (2) Meta Movement SDK (markerless inside-out optical tracking), and (3) Vive Trackers (marker-based outside-in optical tracking with IMUs). In a 3x5 mixed-design, participants performed five tasks, simulating different use cases, to probe distinct aspects of these systems. No system consistently outperformed the others. Meta excelled in hand-based, fast-paced interactions, while Captury and Vive performed better in lower-body tasks and during full-body pose observation. These findings underscore the need to evaluate reduced user-worn IVR systems within the specific use case. We offer practical guidance for system selection based on use-case demands and released our tasks as an open-source, extensible framework to support future evaluations for selecting IVR systems.

Abstract: Body weight issues can manifest in low self-esteem through a negative body image or the feeling of unattractiveness. To explore potential interventions, the pilot study examined whether embodying a photorealistically personalized avatar with enhanced attractiveness affects self-esteem. Participants in the manipulation group adjusted their avatar's body weight to their self-defined ideal, while a control group used unmodified avatars. To confirm the manipulation, we measured the perceived avatars' attractiveness. Results showed that participants found avatars at their ideal weight significantly more attractive, confirming an effective manipulation. Further, the ideal weight group showed a clear trend towards higher self-esteem post-exposure.

Abstract: Body image distortions in anorexia nervosa pose significant therapeutic challenges, requiring innovative interventions. Virtual Reality (VR) and Augmented Reality (AR) technologies offer promising solutions, yet stakeholder preferences, from therapists and patients, remain unexplored. This methodological proposal outlines focus groups to compare VR and AR mirror exposures using personalized and body-weight-modifiable avatars in anorexia nervosa therapy. Therapists will evaluate therapeutic potential, risks, and practicality, while adolescent patients will assess comfort, stress responses, and usability. The findings aim to advance the user-centered integration of VR and AR into anorexia nervosa therapy, addressing critical treatment gaps.

Abstract: This paper investigates if and how self-similarity and having motor control impact sense of embodiment, self-identification, and body weight perception in Augmented Reality (AR). We conducted a 2x2 mixed design experiment involving 60 participants who interacted with either synchronously moving virtual humans or independently moving ones, each with self-similar or generic appearances, across two consecutive AR sessions. Participants evaluated their sense of embodiment, self-identification, and body weight perception of the virtual human. Our results show that self-similarity significantly enhanced sense of embodiment, self-identification, and the accuracy of body weight estimates with the virtual human. However, the effects of having motor control over the virtual human movements were notably weaker in these measures than in similar VR studies. Further analysis indicated that not only the virtual human itself but also the participants' body weight, self-esteem, and body shape concerns predict body weight estimates across all conditions. Our work advances the understanding of virtual human body weight perception in AR systems, emphasizing the importance of factors such as coherence with the real-world environment.

Abstract: Our work investigates the influence of self-related cues in the design of virtual humans on body perception in virtual reality. In a 2x2 mixed design, 64 participants faced photorealistic virtual humans either as a motion-synchronized embodied avatar or as an autonomous moving agent, appearing subsequently with a personalized and generic texture. Our results unveil that self-related cues through embodiment and personalization yield an individual and complemented increase in participants' sense of embodiment and self-identification towards the virtual human. Different body weight modification and estimation tasks further showed an impact of both factors on participants' body weight perception. Additional analyses revealed that the participant's body mass index predicted body weight estimations in all conditions and that participants' self-esteem and body shape concerns correlated with different body weight perception results. Hence, we have demonstrated the occurrence of double standards through induced self-related cues in virtual human perception, especially through embodiment.

Abstract: Our work investigates the impact of virtual human embodiment and personalization on the sense of embodiment (SoE) and self-identification (SI). We introduce preliminary items to query self-similarity (SS) and self-attribution (SA) with virtual humans as dimensions of SI. In our study, 64 participants successively observed personalized and generic-looking virtual humans, either as embodied avatars in a virtual mirror or as agents while performing tasks. They reported significantly higher SoE and SI when facing personalized virtual humans and significantly higher SoE and SA when facing embodied avatars, indicating that both factors have strong separate and complimentary influence on SoE and SI.

Abstract: Mirror self-reflection can help us to develop a deeper understanding and appreciation of our body. Due to technological advancements, holographic augmented reality (AR) mirrors can create realistic visualizations of virtual humans that can represent one's appearance in an altered way while remaining in a familiar environment. Further developing those mirrors opens a new field for use in everyday life. In this work, we outline possible future scenarios where AR mirrors can empower individuals to visualize their emotions, thought patterns, and discrepancies related to their physical body and mental body image. Thus, AR mirrors can encourage their self-reflection, promote a positive and healthy relationship with their bodies, or motivate them to take action to improve their well-being.

Abstract: The embodiment of avatars in virtual reality (VR) is a promising tool for enhancing the user's mental health. A great example is the treatment of body image disturbances, where eliciting a full-body illusion can help identify, visualize, and modulate persisting misperceptions. Augmented reality (AR) could complement recent advances in the field by incorporating real elements, such as the therapist or the user's real body, into therapeutic scenarios. However, research on the use of AR in this context is very sparse. Therefore, we present a holographic AR mirror system based on an optical see-through (OST) device and markerless body tracking, collect valuable qualitative feedback regarding its user experience, and compare quantitative results regarding presence, embodiment, and body weight perception to similar systems using video see-through (VST) AR and VR. For our OST AR system, a total of 27 normal-weight female participants provided predominantly positive feedback on display properties (field of view, luminosity, and transparency of virtual objects), body tracking, and the perception of the avatar’s appearance and movements. In the quantitative comparison to the VST AR and VR systems, participants reported significantly lower feelings of presence, while they estimated the body weight of the generic avatar significantly higher when using our OST AR system. For virtual body ownership and agency, we found only partially significant differences. In summary, our study shows the general applicability of OST AR in the given context offering huge potential in future therapeutic scenarios. However, the comparative evaluation between OST AR, VST AR, and VR also revealed significant differences in relevant measures. Future work is mandatory to corroborate our findings and to classify the significance in a therapeutic context.