Virtual reality (VR) technology offers highly controlled immersive experiences that can be used to conduct spatial cognition research. However, there are VR-specific perceptual biases that reduce its ability to generalize all findings to real-world scenarios. One specific bias causes observers to perceive objects as closer than intended, a phenomenon called distance compression. Although prior research has focused primarily on visual and technological solutions to distance compression, using other senses as a potential remedy (e.g., hearing) for the bias has not been explored. Here, participants completed both a blind-walking task for distance estimation and a cross-modal perceptual-matching task to evaluate audiovisual spatial displacement. The results showed that real-world sounds spatially displaced both in front of and behind a corresponding visual target increased the accuracy of blind walking relative to vision-only cues, albeit with a small effect. Individual differences measures, including performance on the perceptual-matching task and the relative variability of auditory and visual stimuli, did not account for the individual differences in the effectiveness of spatially displaced sounds. Overall, this study demonstrates the potential for adding multisensory information (specifically the addition of non-virtual sounds) to improve the accuracy of distance perception in VR.

Historically, distances are underestimated in virtual environments, and a mismatch between a participant's inter-pupillary distance (IPD) and the inter-axial distance (IAD) of the head-mounted display (HMD) could contribute to underestimation, but prior work has not examined how this interacts with lens type or target location in the visual field. Prior work testing the effects of IPD mismatch on distance perception in immersive virtual environments (IVEs) shows mixed results for distances within 2-10 meters. One limitation is that this work did not consider the variety of optical lenses employed in different HMDs. The lens type could affect distance perception differently depending on IPD and could affect it even more for targets appearing on the sides of the display rather than in front of the user. We examined whether the HMD type and location of targets in the virtual visual field affect perception when IPD is mismatched and matched. Using a blind walking task, participants judged the distance to targets that were either in front or to the side of the participant. One group viewed targets in the Varjo XR-3 and the other viewed them in the HTC Vive Pro. We found that distances were judged to be farther in the periphery than in front of users for both devices. Only in the HTC Vive Pro did an increase in IPD mismatch result in increased distance estimates for targets presented directly in front of the participant. Directional angular error (error observed in orienting to the target) increased as the target angle increased for both devices. However, in the Varjo XR-3, a higher IPD mismatch resulted in greater angular error when viewing targets to the side. Overall, the findings show that a mismatched IPD can affect depth and orientation judgments depending on target position in the display. However, there are differences in both FOV and resolution that could influence distance and orientation perception. A second experiment was conducted to examine whether these factors contributed to perception. To test for this, we down-sampled the Varjo XR-3 to match the horizontal field of view and resolution of the HTC Vive Pro. We found that orientation error was mostly affected by resolution and FOV as the adjusted Varjo XR-3 yielded similar orientation perception as the HTC Vive Pro. With this knowledge, researchers should consider HMDs, IPD, and viewing area in the display as possible influences on distance and orientation perception in order to make VR accessible and accurate to all users.

How children perceive and interact in immersive virtual environments (IVEs) is an important and emerging topic as virtual reality devices proliferate among this age group. How children understand their opportunities for action in an IVE — the perceived affordances of the space — in comparison to adults has, in particular, been rarely studied. This paper addresses this gap by examining children and adults’ reaching affordances in IVEs. We compared how children and adults judge their ability to reach up and out to targets at different distances in an IVE and how feedback from their actions may influence their accuracy. We found that both children and adults tend to overestimate their reaching capabilities, particularly when reaching out. However, by allowing them to actually reach up or out to the targets (action-outcome feedback), both groups significantly re-calibrated their judgments to align their estimates more closely with their actual capabilities. Notably, children exhibited greater initial overestimation than adults but recalibrated at a similar rate. These findings provide novel insights into how children interact with IVEs and suggest that well-designed feedback mechanisms can enhance their accuracy in action-based tasks. This work has implications for the design of IVEs for children, particularly in educational and training contexts, where ensuring accurate perception of capabilities is critical for learning and safety. By investigating both horizontal and vertical reach, this paper contributes to the understanding of affordance perception across age groups in IVEs, marking an essential step in adapting virtual reality technology to younger users.

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.

Virtual reality (VR) has become widely accessible through the development of more commercially available head-mounted displays (HMDs). This accessibility has particularly increased the use of VR in children. However, much of the previous research on understanding perception and action in virtual reality has only been conducted on adults, leaving many open questions about how children perceive and interact with virtual environments. In this paper, we examine whether there are age-related differences in judging the ability to step over a gap using immersive VR. Affordances are a useful measure for understanding objective perceptions of the actions that can be performed in an immersive virtual environment. Such measures are particularly well suited for children given they can easily respond yes or no as to whether they perceive that they can step over a gap. Further, manipulations of the size of virtual body parts could allow us to ascertain how much children rely on the perceived size of their bodies to make decisions about actions. In Experiment 1, adults and children saw motion-tracked virtual feet that were either larger or smaller than their actual foot size. They had to respond as to whether they could step over gaps that varied in width. They also gave perceptual estimates of the width of the gap in feet or meters. The results showed that adults who experience the smaller virtual feet underestimated their stepping ability more than adults with the larger feet. However, children had the opposite effect, such that seeing smaller virtual feet led to an overestimation of their stepping ability. To test whether this age-related difference in body scaling was due to misperception of foot size, adults and children matched virtual shoes to their actual feet size in Experiment 2. This matching task showed no perceptual differences between the age groups. Across our two experiments, we showed that children scale gap affordance judgments differently than adults and this difference cannot be explained by difference in perceptions of the size of virtual feet. The results suggest that children can effectively make perception and action judgments in virtual reality, but do not always do so in the same manner as adults. Such a finding has implications for the design of virtual reality games, educational tools, and training systems that are becoming increasingly common for children.

Accurate perception of one’s action capabilities, or affordance perception, is essential for successful interaction with both real and virtual environments. Affordance perception can potentially be improved by receiving feedback. It is unknown what specific types of feedback are needed for improvements in affordance perception to occur, particularly in virtual environments where cues may be impoverished. The current work studied perception of horizontal reachability in virtual and augmented reality (VR and AR), specifically whether it would improve with feedback, and if any improvement transferred to the real world. Multiple types of feedback were studied in VR or AR: exploratory behavior, static outcome, and action outcome feedback. Our results indicate that exploratory behavior is sufficient for improvement in perceived reachability in VR, but in AR, outcome feedback is necessary. In both VR and AR, outcome feedback was required for improvement in perceived reachability to transfer to the real world. These findings have practical implications for training in virtual environments. If virtual environments are used for training actions that ultimately need to be performed in the real world, outcome feedback should be provided.

Immersive virtual environments (VEs) are most useful for training and education when viewers perceive and act accurately within them. Judgments of action capabilities within a VE provide a good measure of perceptual fidelity - the notion of how closely perception and action in the VE match that in the real world - and can also assess how perception for action may be calibrated with visual feedback based on one's own actions. In the current study we tested judgments of action capabilities within a VE for two different reaching behaviors: reaching out and reaching up. Our goal was to assess whether feedback from actual reaching improves judgments and if any recalibration due to feedback differed across reaching behaviors. We first measured participants' actual reaching out and reaching up capabilities so that feedback trials could be scaled to their actual abilities. Participants then completed blocks of alternating perceptual adjustment and feedback trials. In adjustment trials, they adjusted a virtual target to a distance perceived to be just reachable. In feedback trials, they viewed targets that were farther or closer than their actual reach, decided whether the target was reachable, and then reached out to the target to receive visual feedback from a hand-held controller. The first feedback block manipulated the target distance to be 30% over or under actual reach and subsequent blocks decreased the deviation to 20%,10% and 5% of actual reach. We found that for both reaching behaviors, reach was initially overestimated, and then perceptual estimations decreased to become more accurate over feedback blocks. Accuracy in the feedback trials themselves showed that targets just beyond reach were more difficult to judge correctly. This study establishes a straightforward methodology that can be used for calibration of actions in VEs and has implications for applications that depend on accurate reaching within VEs.

The Ebbinghaus illusion, also known as Titchner Circles, is a well- known perceptual illusion affecting the perceived size of a disc enclosed by an annulus of either larger or smaller discs. Though many have found highly consistent results with regard to the effect of the illusion on size perception, there have been mixed results when studying its effect on action-based tasks. In this paper, we present a study utilizing a head-worn virtual environment to examine the effect of the Ebbinghaus illusion on depth judgments as measured using a blind-reaching task. We found that participants’ size judgments were symmetrically affected by the classic "large annulus" and "small annulus" configurations, but their distance judgments were asymmetrically affected. Large annulus configurations had no significant effect on distance judgments while small annulus configurations resulted in significant underestimation of target distances. Despite this asymmetry, both configurations resulted in response times of similar magnitude that were significantly longer than those of the non-illusory control condition.

There has long been interest in illusions of self-motion and their perception in virtual environments. Prior work has indicated that an observer's field of view size is an important factor in the perception of self-motion both real and illusory. Restricted fields of view in some virtual reality displays has limited the extent to which this can be studied. In this paper, we discuss a pilot study examining how well observers can discriminate forward motion velocities as viewed through two common, but differing, field of view configurations. We find that observers are quite sensitive to changes in forward motion. The perceived magnitude of this motion is also found to be affected by field of view size with a smaller field of view resulting in slower perceived velocity.

The Depth Light solves the problem of not being able to view the real world, without having to remove the Head Mounted Display, accurately and easily. The Depth Light is activated by a button or trigger press on an HTC Vive controller and consists of a Vive controller, an ultrasonic depth finder, a microcontroller (to send measured distances over serial), a web camera, and a mount for the microcontroller and camera. The device works by finding the distance between the device and the nearest real-world object, taking a sum of these distances, and sending this over serial to a computer as an average. In Unity3D, an object is rendered at the distance sent from the micro controller. This object is then textured with the video feed from the web camera. This object's distance changes in the virtual environment in real time as the Depth Lights micro controller sends new information. As the distance changes the scale of the object also changes, this is to keep the object the same size in the field of vision. The data from the Depth Light is handled by a Unity3D plugin. This plug-in handles all the rendering commands and all of the scaling.