Locomotion is central to human navigation and spatial learning, with natural walking offering the most effective movement in immersive virtual environments (IVEs) due to its rich proprioceptive and vestibular feedback. However, space constraints often limit natural walking in IVEs, prompting the use of omnidirectional treadmills. The Cyberith Virtualizer Elite 2 enables users to walk in place by sliding their feet on a low-friction, tiltable platform while secured in a harness. It allows control over both tilt angle and walking speed, offering researchers flexibility in adjusting sensorimotor cues. In this study, we examined how tilt angle, speed, and training duration affect distance perception and cybersickness. In Experiment 1, we tested three tilt angles (0°, ~8.5°, ~17°) and three speeds (0.8×, 1.0×, 1.2× treadmill speed) during blind walking. A slower speed (0.8×) aligned best with natural walking and minimized cybersickness; users preferred the ~8.5° tilt. Additional analysis identified ~0.7× speed with ~8.5° tilt as preferred. In Experiment 2, we varied training durations (3, 6, or 9 minutes) and found that, with the preferred setup, treadmill distance judgments were comparable to natural walking. At least 6 minutes of training was sufficient for adaptation. These findings offer practical guidance for configuring treadmill locomotion in virtual reality research.

Multi-user virtual reality (VR) systems support multiple locomotion methods, but coordination may be challenging when partners use different methods. We studied dyads navigating a shared virtual maze using symmetric (same) or asymmetric (different) locomotion methods-specifically, steering (continuous movement with physical turning) and teleportation (point-and-teleport within 30 meters with physical turning)-and assessed survey knowledge using direction and straightline distance estimates between objects. We found that (1) dyads acquired better survey knowledge than individuals across locomotion conditions; (2) teleportation showed no significant difference from steering in distance error and yielded significantly lower angular error; (3) asymmetric locomotion methods did not significantly increase cybersickness compared to symmetric locomotion methods; and (4) symmetric and asymmetric dyads showed no significant differences in distance or angular errors. Overall, these results suggest that collaborative navigation improves spatial learning and that asymmetric locomotion can improve accessibility without significantly increasing cybersickness in multi-user VR applications.

Maintaining physical distance is a crucial aspect of social interactions in the real world. This paper investigates how people embodied in self-avatars, manage such spacing in immersive virtual environments. Specifically, we measured how interpersonal distance (IPD) and peripersonal space (PPS) were affected by a surrounding virtual crowd. We designed three crowd density conditions - no crowd, a medium crowd, and a dense crowd - where participants interacted with a virtual human. Additionally, based on the results of a questionnaire, participants were grouped into one of three groups depending on their self-reported comfort level with crowds: some found crowds relaxing, some were indifferent, and some found crowds stressful. Our findings revealed that IPD decreased as crowd density increased, regardless of the participants' groupings. However, PPS exhibited a more nuanced response, with those stressed by a crowd showing heightened sensitivity to crowd density, reflected by larger PPS boundaries, faster reaction times, and less confidence when estimating their PPS boundary. The study also identified significant interactions between crowd density and participants' comfort levels, particularly among the group stressed by a crowd, where heightened stress led to expanded personal space. These results show the critical role of social and environmental factors in shaping spatial perception and behavior in virtual environments.

Most modern head-mounted displays (HMDs) do not support the full range of adult inter-pupillary distances (IPDs) (i.e., 45 – 80 mm) due to technological limitations. Prior work indicates that the mismatch between a user’s actual IPD and the IPD set in the HMD (“IPD mismatch”) can affect distance and size judgments in near space (0 – 2 m). Therefore, users with IPDs outside of the supported HMD IPD range may not perceive virtual environments (VEs) accurately. Across three experiments, we investigated whether IPD mismatch significantly affects peoples’ distance judgments at longer distances (4 – 7 m). In two of the experiments, we recruited participants with IPDs smaller than the minimum supported IPD of the HTC Vive Pro HMD. They estimated distances in action space using verbal estimation (Experiment 1) and blind walking (Experiment 2) measures in indoor VEs. We found that: (i) distances were underestimated in action space, and (ii) IPD mismatch had minimal to no effect on their distance judgments. In a third experiment, we investigated whether we could generalize our findings to participants with an IPD within the supported HMD IPD range. We were able to replicate our previous findings. Overall, our findings suggest that IPD mismatch in an HMD may not be a major factor in distance underestimation in action space in VEs.

Omnidirectional treadmills provide one solution for locomoting through large virtual environments in confined physical spaces. Through two experiments, this paper evaluated locomotion on an omnidirectional treadmill (Cyberith Virtualizer Elite 2) by comparing it to natural walking in an open physical space. In Experiment 1, participants judged distances and completed a path integration task using the treadmill and natural walking. Participants walked further on the treadmill but had larger angular errors during path integration, potentially due to increased cybersickness. Experiment 2 varied path lengths during path integration and found that longer paths led to higher cybersickness scores but did not affect performance. The paper offers interpretations and suggestions for using omnidirectional treadmills in virtual reality.

In this paper, we examine how embodiment and manipulation of a self-avatar's dimensions - specifically the arm length - affect users' judgments of the personal space around them in an immersive virtual environment. In the real world, personal space is the immediate space around the body in which physical interactions are possible. Personal space is increasingly studied in virtual environments because of its importance to social interactions. Here, we specifically look at two components of personal space, interpersonal and peripersonal space, and how they are affected by embodiment and the sizing of a self-avatar. We manipulated embodiment, hypothesizing that higher levels of embodiment will result in larger measures of interpersonal space and smaller measures of peripersonal space. Likewise, we manipulated the arm length of a self-avatar, hypothesizing that while interpersonal space would change with changing arm length, peripersonal space would not. We found that the representation of both interpersonal and peripersonal space change when the user experiences differing levels of embodiment in accordance with our hypotheses, and that only interpersonal space was sensitive to changes in the dimensions of a self-avatar's arms. These findings provide increased understanding of the role of embodiment and self-avatars in the regulation of personal space, and provide foundations for improved design of social interaction in virtual environments.