Effective collaboration in Virtual Reality depends on users' ability to accurately perceive the affordances of others within a shared space. This paper presents the first empirical investigation of how people judge others' reaching capabilities in Immersive Virtual Environments (IVEs). We examined whether observers can reliably estimate the maximum horizontal reach distance of virtual actors, how different actor representations influence these perceptual judgments, and whether calibration feedback can improve estimation accuracy. Participants (N=35) judged the reachability of objects for virtual actors across three visual fidelity conditions: high-fidelity, low-fidelity, and end-effector-only representations. Results demonstrate that users can successfully estimate others' horizontal reachability in IVEs, though with overestimation. Calibration through action feedback significantly improved estimation accuracy, with overestimation decreasing across trials. Visual fidelity showed no main effect on initial reachability judgments but significantly affected postcalibration performance, with low-fidelity representations demonstrating significantly better calibration outcomes compared to high-fidelity avatars, while end-effector-only representations showed no significant difference from either condition. The findings contribute to the social perception literature in Virtual Reality (VR) and to provide design guidelines for avatar systems in collaborative virtual environments, where spatial coordination and shared action planning are critical.

Direct perception, as part of the ecological approach to perception, defines a relationship between an organism and their environment that is specified by lawful information.Researchers can apply the ecological approach to eXtended Reality (XR) work to obtain a richer understanding of users' perception-action coordination in novel virtual settings.To encourage widespread adoption of this theoretical framework, this methodological paper introduces four major concepts from the ecological approach that are highly relevant to XR applications.We also provide an overview of existing literature to illustrate how those concepts may be used to inform and test their designs.These elements include the study of calibration and attunement, affordances, action based responses, and intrinsic scaling for measurements.The goal of this work is to increase awareness of the value of the ecological approach, and to provide a practical, evidence-based reference for researchers interested in applying these techniques in XR research.

Interpupillary distance (IPD) is the most important parameter for creating a user-specific stereo parallax, which in turn is crucial for correct depth perception. This is why contemporary Head-Mounted Displays (HMDs) offer adjustable lenses to adapt to users’ individual IPDs. However, today’s Video See-Through Augmented Reality (VST AR) HMDs use fixed camera placements to reconstruct the stereoscopic view of a user’s environment. This leads to a potential mismatch between individual IPD settings and the fixed Inter-Camera Distances (ICD), which can lead to perceptual incongruencies, limiting the usability and, potentially, the applicability of VST AR in depth-sensitive use cases. To investigate this incongruency between IPD and ICD, we conducted a 2 × 3 mixed-factor design user study using a near-field, open-loop reaching task comparing distance judgments of Virtual Reality (VR) and VST AR. We also investigated changes in reaching performance via perceptual calibration by incorporating a feedback phase between pre- and post-phase conditions, with a particular focus on the influence of IPD-ICD differences. Our Linear Mixed Model (LMM) analysis showed a significant difference between VR and VST AR, an effect of IPD-ICD mismatch, and a combined effect of both factors. However, subjective measures showed no effect underlining the subconscious nature of the perception of VST AR. This novel insight and its consequences are discussed specifically for depth perception tasks in AR, eXtended Reality (XR), and potential use cases.

Little research has studied how people use Virtual Reality (VR) changes as they experience VR. This article reports the results of an experiment investigating how users’ behavior with two locomotion methods changed over 4 weeks: teleportation and joystick-based locomotion. Twenty novice VR users (with no more than 1 hour prior experience with any form of walking in VR) were recruited. They loaned an Oculus Quest for 4 weeks on their own time, including an activity we provided them with. Results showed that the time required to complete the navigation task decreased faster for joystick-based locomotion. Spatial memory improved with time, particularly when using teleportation (which starts disadvantaged to joystick-based locomotion). In addition, overall cybersickness decreased slightly over time; however, two dimensions of cybersickness (nausea and disorientation) increased notably over time using joystick-based navigation.

This work explored how users’ sensitivity to offsets in their avatars’ virtual hands changes as they gain exposure to virtual reality. We conducted an experiment using a two-alternative forced choice (2-AFC) design over the course of 4 weeks, split into four sessions. The trials in each session had a variety of eight offset distances paired with eight offset directions (across a two-dimensional plane). While we did not find evidence that users became more sensitive to the offsets over time, we did find evidence of behavioral changes. Specifically, participants’ head–hand coordination and completion time varied significantly as the sessions went on. We discuss the implications of both results and how they could influence our understanding of long-term calibration for perception-action coordination in virtual environments.

Redirected walking techniques use rotational gains to guide users away from physical obstacles as they walk in a virtual world, effectively creating the illusion of a larger virtual space than is physically present. Designers often want to keep users unaware of this manipulation, which is made possible by limitations in human perception that render rotational gains imperceptible below a certain threshold. Many aspects of these thresholds have been studied; however, no research has yet considered whether these thresholds may change over time as users gain more experience with them. To study this, we recruited 20 novice VR users (no more than 1 hour of prior experience with an HMD) and provided them with an Oculus Quest to use for 4 weeks on their own time. They were tasked to complete an activity assessing their sensitivity to rotational gain once each week, in addition to whatever other activities they wanted to perform. No feedback was provided to participants about their performance during each activity, minimizing the possibility of learning effects accounting for any observed changes over time. We observed that participants became significantly more sensitive to rotation gains over time, underscoring the importance of considering prior user experience in applications involving rotational gain, as well as how prior user experience may affect other, broader applications of VR.

Prior research in depth perception and perceptuo-motor calibration have primarily focused on participants completing experiments in single sessions and therefore do not empirically evaluate changes over time. Further, these studies do not typically take into account the amount of experience that the participants have in virtual reality (VR) prior to participation, the role of experience during participation, or calibration that may occur throughout the experiment session. In this contribution, we conducted a novel empirical evaluation of how calibration affects perception-action coordination over time. We recruited novice VR users and they completed eight sessions of a depth perception reaching experiment over the course of 12 weeks. During these experiments, we examined how participants' ability to estimate depth in a virtual environment changed as they gradually gained experience. While previous literature has shown that participants tend to underestimate distances, we found that this underestimation diminished over time as they gained experience in the virtual environment. Our study highlights the need for carrying out VR studies over time and the influence that longitudinal calibration can have on spatial perception in long-term VR experiences.