Computer Science

We report an ex periment where participants observed an attack on their virtual body as ex perienced in an immersive virtual reality (IVR) system. Participants sat by a table with their right hand resting upon it. In IVR they saw a virtual table that was registered with the real one, and they had a virtual body that substituted their real body seen from a first person perspective. The virtual right hand was collocated with their real right hand. Event-related brain potentials (ERPs) were recorded in two conditions, one where the participant's virtual hand was attacked with a knife and a control condition where the knife only struck the virtual table. Significantly greater P450 potentials were obtained in the attack condition confirming our ex pectations that participants had a strong illusion of the virtual hand being their own, which was also strongly supported by questionnaire responses. Higher levels of subjective virtual hand ownership correlate with larger P450 amplitudes. Mu-rhythm Event Related Desynchronization (ERD) in the motor cortex , and Readiness Potential (C3-C4) negativity were clearly observed when the virtual hand was threatened-as would be ex pected if the real hand was threatened and the participant tried to avoid harm. Our results support the idea that eventrelated potentials (ERPs) may provide a promising non-subjective measure of virtual embodiment. They also support previous ex periments on pain observation and are placed into contex t of similar ex periments and studies of body-perception and body-ownership within cognitive neuroscience.

Inside virtual reality, users can embody avatars that are collocated from a first-person perspective. When doing so, participants have the feeling that the own body has been substituted by the self-avatar, and that the new body is the source of the sensations. Embodiment is complex as it includes not only body ownership over the avatar, but also agency, co-location, and external appearance. Despite the multiple variables that influence it, the illusion is quite robust, and it can be produced even if the self-avatar is of a different age, size, gender, or race from the participant's own body. Embodiment illusions are therefore the basis for many social VR experiences and a current active research area among the community. Researchers are interested both in the body manipulations that can be accepted, as well as studying how different self-avatars produce different attitudinal, social, perceptual, and behavioral effects. However, findings suggest that despite embodiment being strongly associated with the performance and reactions inside virtual reality, the extent to which the illusion is experienced varies between participants. In this paper, we review the questionnaires used in past experiments and propose a standardized embodiment questionnaire based on 25 questions that are prevalent in the literature. We encourage future virtual reality experiments that include first-person virtual avatars to administer this questionnaire in order to evaluate the degree of embodiment.

Radio frequency ablation is a minimally invasive intervention that introduces-under 2D ultrasound guidance and via a needle-like probe-highfrequency electrical current into non-resectable hepatic tumors. These recur mostly on the periphery, indicating errors in probe placement. Hypothesizing that a contextually correct 3D display will aid targeting and decrease recurrence, we have developed a prototype guidance system based on a head-tracked 3D display and motion-tracked instruments. We describe our reasoning and our experience in selecting components for, designing and constructing the 3D display. Initial candidates were an augmented reality see-through head-mounted display and a virtual reality "fish tank" system. We describe the system requirements and explain how we arrived at the final decision. We show the operational guidance system in use on phantoms and animals.

Implicit social biases play a critical role in shaping our attitudes towards other people. Such biases are thought to arise, in part, from a comparison between features of one's own self-image and those of another agent, a process known as 'bodily resonance'. Recent data have demonstrated that implicit bias can be remarkably plastic, being modulated by brief immersive virtual reality experiences that place participants in a virtual body with features of an out-group member. Here, we provide a mechanistic account of bodily resonance and implicit bias in terms of a putative self-image network that encodes associations between different features of an agent. When subsequently perceiving another agent, the output of this self-image network is proportional to the overlap between their respective features, providing an index of bodily resonance. By combining the self-image network with a drift diffusion model of decision making, we simulate performance on the implicit association test (IAT) and show that the model captures the ubiquitous implicit bias towards in-group members. We subsequently demonstrate that this implicit bias can be modulated by a simulated illusory body ownership experience, consistent with empirical data; and that the magnitude and plasticity of implicit bias correlates with self-esteem. Hence, we provide a simple mechanistic account of bodily resonance and implicit bias which could contribute to the development of interventions for reducing the negative evaluation of social out-groups.

In this special issue of IEEE Transactions on Visualization and Computer Graphics (TVCG), we are pleased to present the journal papers from the 20th IEEE International Symposium on Mixed and Augmented Reality (ISMAR 2021), which will be held as a virtual conference between October 4 and 8, 2021. ISMAR continues the over twenty year long tradition of IWAR, ISMR, and ISAR, and is the premier conference for Mixed and Augmented Reality in the world. There are 24 papers in this special issue, which were selected from 122 submissions, for an acceptance rate of 19.67%. Of these 122 submissions, 3 submissions were desk rejected and 1 submission was quick rejected. These papers were either not anonymized or did not contain enough detail to replicate the work. In total, 118 papers went out for full review. 114 papers received four reviews plus a meta review, and 4 papers received five reviews plus a meta review. Each paper has an overall score calculated as the mean of the reviewers' scores. Reviewers rated each submission on a scale from one to six. The overall mean paper score was 3.08 (SD=.95), 75% of the submissions received a mean score below 3.75, and 84% a mean score of 4.25 and lower. As program chairs we aimed for the highest possible reviewing standards and conducted a decision process that aimed for final decisions in a fair, rigorous, and transparent way. There was a single paper submission category, papers from 4 to 9 pages in length, plus 2 pages of references. All submissions underwent a review process that encompassed two reviewing stages, overseen by a coordinator from the Program Committee (PC), which comprised 40 internationally renowned experts from the Asia-Pacific region, the Americas, and Europe. After PC members had declared their conflicts and provided their preferences, the program chairs assigned coordinators. For every PC member, as well as the program chairs, for every paper where they had a conflict of interest, both the reviewer assignments and reviewer names were hidden. We used a double-blind process to allow for a fairer reviewing process. Thus, the external reviewers were not aware of the identity of the authors. After all reviews were received, authors were permitted, though not required, to submit a rebuttal. During the rebuttal phase reviewers were able to read other reviews. After the rebuttal phase an online discussion phase among the reviewers started, in which the reviewers for each paper came to a consensual initial recommendation for that

Fig. 3. A selection of avatars animated with the MoveBox system. a) Person doing live MoCap from Azure Kinect onto a Microsoft Rocketbox avatar. b) Playback of two avatar animations created to represent a social interaction with MoveBox. c) A crowd of avatars dancing powered by Mocap.

Radio frequency ablation is a minimally invasive intervention that introduces -- under 2D ultrasound guidance and via a needle-like probe -- high-frequency electrical current into non-resectable hepatic tumors. These recur mostly on the periphery, indicating errors in probe placement. Hypothesizing that a contextually correct 3D display will aid targeting and decrease recurrence, we have developed a prototype guidance system based on a head-tracked 3D display and motion-tracked instruments. We describe our reasoning and our experience in selecting components for, designing and constructing the 3D display. Initial candidates were an augmented reality see-through head-mounted display and a virtual reality "fish tank" system. We describe the system requirements and explain how we arrived at the final decision. We show the operational guidance system in use on phantoms and animals.

Virtual reality technology is biased. It excludes approximately 95% the world’s population by being primarily designed for male, western, educated, industrial, rich, and democratic populations. This bias may be due to the lack of diversity in virtual reality researchers, research participants, developers, and end users, fueling a noninclusive research, development, and usability cycle. The objective of this paper is to highlight the minimal virtual reality research involving understudied populations with respect to dimensions of diversity, such as gender, race, culture, ethnicity, age, disability, and neurodivergence. Specifically, we highlight numerous differences in virtual reality usability between underrepresented groups compared to commonly studied populations. These differences illustrate the lack of generalizability of prior virtual reality research. Lastly, we present a call to action with the aim that, over time, will break the cycle and enable virtual reality for everyone....

Although it has been shown that immersive virtual reality (IVR) can be used to induce illusions of ownership over a virtual body (VB), information on whether this changes implicit interpersonal attitudes is meager. Here we demonstrate that embodiment of light-skinned participants in a dark-skinned VB significantly reduced implicit racial bias against darkskinned people, in contrast to embodiment in light-skinned, purple-skinned or with no VB. 60 females participated in this between-groups experiment, with a VB substituting their own, with full-body visuomotor synchrony, reflected also in a virtual mirror. A racial Implicit Association Test (IAT) was administered at least three days prior to the experiment, and immediately after the IVR exposure. The change from pre-to post-experience IAT scores suggests that the dark-skinned embodied condition decreased implicit racial bias more than the other conditions. Thus, embodiment may change negative interpersonal attitudes and thus represent a powerful tool for exploring such fundamental psychological and societal phenomena.

Redirected Free Exploration with Distractors (RFED) is a large-scale real-walking locomotion interface developed to enable people to walk freely in virtual environments that are larger than the tracked space in their facility. This paper describes the RFED system in detail and reports on a user study that evaluated RFED by comparing it to walking-in-place and joystick interfaces. The RFED system is composed of two major components, redirection and distractors. This paper discusses design challenges, implementation details, and lessons learned during the development of two working RFED systems. The evaluation study examined the effect of the locomotion interface on users' cognitive performance on navigation and wayfinding measures. The results suggest that participants using RFED were significantly better at navigating and wayfinding through virtual mazes than participants using walking-in-place and joystick interfaces. Participants traveled shorter distances, made fewer wrong t...

Fig. 1. Viewing a self-avatar in a virtual mirror: In the image on the left the eyes of the avatar are fixed with respect to the head, preventing the participant from moving their head while maintaining eye contact with their avatar's reflection. In the image on the right the avatar's eyes rotate, enabling the participant to maintain eye contact while moving their head.

Immersive Virtual Environments (VEs) enable user controlled interactions within the environment such as head-controlled point-of-view and user-controlled locomotion. In the real world people usually locomote by walking; walking is simple and natural, and enables people not only to move between locations, but also to develop cognitive maps, or mental representations, of environments. People navigate every day in the real world without problem, however users navigating VEs often become disoriented and frustrated, and find it challenging to transfer spatial knowledge acquired in the VE to the real world. In this dissertation I develop and demonstrate the effectiveness of a new locomotion interface, Redirected Free Exploration with Distractors (RFED) that enables people to freely walk in large scale VEs. RFED is the combination of distractors--objects, sounds, or combinations of objects and sounds in the VE that encourage people to turn their heads, and redirection--making the user turn...

Fig. 1. Illustration of two Adobe Mixamo virtual humans captured on the Microsoft HoloLens via its screen capture software. Due to the additive light model employed by this display and most current-state optical see-through displays, the Black person appears more transparent (less opaque) than the White person. This is apparent when observing how the background texture of the door is clearly visible through the Black person but is otherwise not as noticeable through the White person. In practice, this effect is more noticeable than it appears in this figure, as the screen capture software does not factor in effects of environment lighting when generating images.

Fig. 1. Illustration of two Adobe Mixamo virtual humans captured on the Microsoft HoloLens via its screen capture software. Due to the additive light model employed by this display and most current-state optical see-through displays, the Black person appears more transparent (less opaque) than the White person. This is apparent when observing how the background texture of the door is clearly visible through the Black person but is otherwise not as noticeable through the White person. In practice, this effect is more noticeable than it appears in this figure, as the screen capture software does not factor in effects of environment lighting when generating images.