Cybersickness, or sickness caused by virtual reality (VR), represents a significant threat to the usability of VR applications. Repeated exposure to the same VR stimulus causes a reduction in cybersickness, referred to as Cybersickness Abatement from Repeated Exposure (CARE). This study examined whether the benefits of CARE generalize across distinct VR contexts, which was operationalized as three distinct games (a climbing game, a puzzle game, and a stealth survival game). Participants played a VR game for up to 20 minutes. Those in the Repeated Exposure condition played one VR game (either a puzzle game or a climbing game) on three separate days followed by a different VR game (a survival game) on the fourth day. Those in the Single Exposure condition played the survival game once. The three games all differed in several ways, including environment and task, whereas the puzzle and survival games shared a similar joystick locomotion interface that differed from the locomotion interface in the climbing game. Results indicate that cybersickness on Day 4 of the Repeated Exposure condition was significantly lower than that in the Single Exposure condition, regardless of which game was experienced on Days 1-3. The practical implication of this finding is that CARE that occurs in one VR context can generalize to a novel context with a distinct environment, task, and locomotion interface. Results are considered in the context of multiple theoretical explanations for CARE, including sensory rearrangement and habituation. These results support systematic exposure as an approach to reducing cybersickness.

Cybersickness, or sickness induced by virtual reality (VR), negatively impacts the enjoyment and adoption of the technology. One method that has been used to reduce sickness is repeated exposure to VR, herein Cybersickness Abatement from Repeated Exposure (CARE). However, high sickness levels during repeated exposure may discourage some users from returning. Field of view (FOV) restriction reduces cybersickness by minimizing visual motion in the periphery, but also negatively affects the user's visual experience. This study explored whether CARE that occurs with FOV restriction generalizes to a full FOV experience. Participants played a VR game for up to 20 minutes. Those in the Repeated Exposure Condition played the same VR game on four separate days, experiencing FOV restriction during the first three days and no FOV restriction on the fourth day. Results indicated significant CARE with FOV restriction (Days 1--3). Further, cybersickness on Day 4, without FOV restriction, was significantly lower than that of participants in the Single Exposure Condition, who experienced the game without FOV restriction only on one day. The current findings show that significant CARE can occur while experiencing minimal cybersickness. Results are considered in the context of multiple theoretical explanations for CARE, including sensory rearrangement, adaptation, habituation, and postural control.

Multiple tools are available to reduce cybersickness (sickness caused by virtual reality), but past research has not investigated the combined effects of multiple mitigation tools. Field of view (FOV) restriction limits peripheral vision during self-motion, and ample evidence supports its effectiveness for reducing cybersickness. Snap turning involves discrete rotations of the user's perspective without presenting intermediate views, although reports on its effectiveness at reducing cybersickness are limited and equivocal. Both mitigation tools reduce the visual motion that can cause cybersickness. The current study (N = 201) investigated the individual and combined effects of FOV restriction and snap turning on cybersickness when playing a consumer virtual reality game. FOV restriction and snap turning in isolation reduced cybersickness compared to a control condition without mitigation tools. Yet, the combination of FOV restriction and snap turning did not further reduce cybersickness beyond the individual tools in isolation, and in some cases the combination of tools led to cybersickness similar to that in the no mitigation control. These results indicate that caution is warranted when combining multiple cybersickness mitigation tools, which can interact in unexpected ways.

Distances are commonly underperceived in virtual reality (VR), and this finding has been documented repeatedly over more than two decades of research. Yet, there is evidence that perceived distance is more accurate in modern compared to older head-mounted displays (HMDs). This meta-analysis, based on 137 samples from 61 publications, describes egocentric distance perception across 20 HMDs and examines the relationship between perceived distance and technical HMD characteristics. Judged distance was positively associated with HMD field of view (FOV), positively associated with HMD resolution, and negatively associated with HMD weight. The effects of FOV and resolution were more pronounced among heavier HMDs. These findings suggest that future improvements in these technical characteristics may be central to resolving the problem of distance underperception in VR.

The wide availability of consumer-oriented virtual reality (VR) equipment has enabled researchers to recruit existing VR owners to participate remotely using their own equipment. Yet, there are many differences between lab environments and home environments, as well as differences between participant samples recruited for lab studies and remote studies. This paper replicates a lab-based experiment on VR locomotion interfaces using a remote sample. Participants completed a triangle-completion task (travel two path legs, then point to the path origin) using their own VR equipment in a remote, unsupervised setting. Locomotion was accomplished using two versions of the teleporting interface varying in availability of rotational self-motion cues. The size of the traveled path and the size of the surrounding virtual environment were also manipulated. Results from remote participants largely mirrored lab results, with overall better performance when rotational self-motion cues were available. Some differences also occurred, including a tendency for remote participants to rely less on nearby landmarks, perhaps due to increased competence with using the teleporting interface to update self-location. This replication study provides insight for VR researchers on aspects of lab studies that may or may not replicate remotely.

The number of people who own a virtual reality (VR) head-mounted display (HMD) has reached a point where researchers can readily recruit HMD owners to participate remotely using their own equipment. However, HMD owners recruited online may differ from the university community members who typically participate in VR research. HMD owners (n=220) and non-owners (n=282) were recruited through two online work sites-Amazon's Mechanical Turk and Prolific-and an undergraduate participant pool. Participants completed a survey in which they provided demographic information and completed measures of HMD use, video game use, spatial ability, and motion sickness susceptibility. In the context of the populations sampled, the results provide 1) a characterization of HMD owners, 2) a snapshot of the most commonly owned HMDs, 3) a comparison between HMD owners and non-owners, and 4) a comparison among online workers and undergraduates. Significant gender differences were found: men reported lower motion sickness susceptibility and more video game hours than women, and men outperformed women on spatial tasks. Men comprised a greater proportion of HMD owners than non-owners, but after accounting for this imbalance, HMD owners did not differ appreciably from non-owners. Comparing across recruitment platform, male undergraduates outperformed male online workers on spatial tests, and female undergraduates played fewer video game hours than female online workers. The data removal rate was higher from Amazon compared to Prolific, possibly reflecting greater dishonesty. These results provide a description of HMD users that can inform researchers recruiting remote participants through online work sites. These results also signal a need for caution when comparing in-person VR research that primarily enrolls undergraduates to online VR research that enrolls online workers.

Virtual reality systems typically allow users to physically walk and turn, but virtual environments (VEs) often exceed the available walking space. Teleporting has become a common user interface, whereby the user aims a laser pointer to indicate the desired location, and sometimes orientation, in the VE before being transported without self-motion cues. This study evaluated the influence of rotational self-motion cues on spatial updating performance when teleporting, and whether the importance of rotational cues varies across movement scale and environment scale. Participants performed a triangle completion task by teleporting along two outbound path legs before pointing to the unmarked path origin. Rotational self-motion reduced overall errors across all levels of movement scale and environment scale, though it also introduced a slight bias toward under-rotation. The importance of rotational self-motion was exaggerated when navigating large triangles and when the surrounding environment was large. Navigating a large triangle within a small VE brought participants closer to surrounding landmarks and boundaries, which led to greater reliance on piloting (landmark-based navigation) and therefore reduced-but did not eliminate-the impact of rotational self-motion cues. These results indicate that rotational self-motion cues are important when teleporting, and that navigation can be improved by enabling piloting.

Vision in real environments stabilizes balance compared to an eyes-closed condition. For virtual reality to be safe and fully effective in applications such as physical rehabilitation, vision in virtual reality should stabilize balance as much as vision in the real world. Older virtual reality technology was previously found to stabilize balance but by less than half as much as real-world vision. Recent advancements in display technology might allow for vision in virtual reality to be as stabilizing as vision in the real world. This study evaluated whether viewing a virtual environment through the HTC Vive—a new consumer-grade head-mounted display—stabilizes balance, and whether visual stabilization is similar to that provided by real-world vision. Participants viewed the real laboratory or a virtual replica of the laboratory and attempted to maintain an unstable stance with eyes open or closed while standing at one of two viewing distances. Vision was significantly stabilizing in all conditions, but the virtual environment provided less visual stabilization than did the real environment. Regardless of the environment, near viewing led to greater visual stabilization than did far viewing. The smaller stabilizing influence of viewing a virtual compared to real environment might lead to greater risk of falls in virtual reality and smaller gains in physical rehabilitation using virtual reality.

The accuracy of machine learning tasks critically depends on high quality ground truth data. Therefore, in many cases, producing good ground truth data typically involves trained professionals; however, this can be costly in time, effort, and money. Here we explore the use of crowdsourcing to generate a large number of training data of good quality. We explore an image analysis task involving the segmentation of corn tassels from images taken in a field setting. We investigate the accuracy, speed and other quality metrics when this task is performed by students for academic credit, Amazon MTurk workers, and Master Amazon MTurk workers. We conclude that the Amazon MTurk and Master Mturk workers perform significantly better than the for-credit students, but with no significant difference between the two MTurk worker types. Furthermore, the quality of the segmentation produced by Amazon MTurk workers rivals that of an expert worker. We provide best practices to assess the quality of ground truth data, and to compare data quality produced by different sources. We conclude that properly managed crowdsourcing can be used to establish large volumes of viable ground truth data at a low cost and high quality, especially in the context of high throughput plant phenotyping. We also provide several metrics for assessing the quality of the generated datasets.

Distance is commonly underperceived in virtual environments (VEs) compared to real environments. Past work suggests that displaying a replica VE based on the real surrounding environment leads to more accurate judgments of distance, but that work has lacked the necessary control conditions to firmly make this conclusion. Other research indicates that walking through a VE with visual feedback improves judgments of distance and size. This study evaluated and compared those two methods for improving perceived distance in VEs. All participants experienced a replica VE based on the real lab. In one condition, participants visually previewed the real lab prior to experiencing the replica VE, and in another condition they did not. Participants performed blind-walking judgments of distance and also judgments of size in the replica VE before and after walking interaction. Distance judgments were more accurate in the preview compared to no preview condition, but size judgments were unaffected by visual preview. Distance judgments and size judgments increased after walking interaction, and the improvement was larger for distance than for size judgments. After walking interaction, distance judgments did not differ based on visual preview, and walking interaction led to a larger improvement in judged distance than did visual preview. These data suggest that walking interaction may be more effective than visual preview as a method for improving perceived space in a VE.

Underperception of egocentric distance in virtual reality has been a persistent concern for almost 20 years. Modern head-mounted displays (HMDs) appear to have begun to ameliorate underperception. The current study examined several aspects of perceived space in the HTC Vive. Blind-walking distance judgments, verbal distance judgments, and size judgments were measured in two distinct virtual environments (VEs)—a high-quality replica of a real classroom and an empty grass field—as well as the real classroom upon which the classroom VE was modeled. A brief walking interaction was also examined as an intervention for improving anticipated underperception in the VEs. Results from the Vive were compared to existing data using two older HMDs (nVisor SX111 and ST50). Blind-walking judgments were more accurate in the Vive compared to the older displays, and did not differ substantially from the real world nor across VEs. Size judgments were more accurate in the classroom VE than the grass VE and in the Vive compared to the older displays. Verbal judgments were significantly smaller in the classroom VE compared to the real classroom and did not significantly differ across VEs. Blind-walking and size judgments were more accurate after walking interaction, but verbal judgments were unaffected. The results indicate that underperception of distance in the HTC Vive is less than in older displays but has not yet been completely resolved. With more accurate space perception afforded by modern HMDs, alternative methods for improving judgments of perceived space—such as walking interaction—may no longer be necessary.

Selection of moving targets is a common, yet complex task in human-computer interaction (HCI) and virtual reality (VR). Predicting user intention may be beneficial to address the challenges inherent in interaction techniques for moving-target selection. This article extends previous models by integrating relative head-target and hand-target features to predict intended moving targets. The features are calculated in a time window ending at roughly two-thirds of the total target selection time and evaluated using decision trees. With two targets, this model is able to predict user choice with up to ~ 72% accuracy on general moving-target selection tasks and up to ~ 78% by also including task-related target properties.

Distance in immersive virtual reality is commonly underperceived relative to intended distance, causing virtual environments to appear smaller than they actually are. However, a brief period of interaction by walking through the virtual environment with visual feedback can cause dramatic improvement in perceived distance. The goal of the current project was to determine how quickly improvement occurs as a result of walking interaction (Experiment 1) and whether improvement is specific to the distances experienced during interaction, or whether improvement transfers across scales of space (Experiment 2). The results show that five interaction trials resulted in a large improvement in perceived distance, and that subsequent walking interactions showed continued but diminished improvement. Furthermore, interaction with near objects (1-2 m) improved distance perception for near but not far (4-5 m) objects, whereas interaction with far objects broadly improved distance perception for both near and far objects. These results have practical implications for ameliorating distance underperception in immersive virtual reality, as well as theoretical implications for distinguishing between theories of how walking interaction influences perceived distance.

Virtual reality systems commonly include both monocular and binocular depth cues, which have the potential to provide viewers with a realistic impression of spatial properties of the virtual environment. However, when multiple viewers share the same display, only one viewer typically receives the projectively correct images. All other viewers experience the same images despite displacement from the center of projection (CoP). Three experiments evaluated perceptual distortions caused by displacement from the CoP and compared those percepts to predictions of models based on monocular and binocular viewing geometry. Leftward and rightward displacement from the CoP caused virtual angles on the ground plane to be judged as larger and smaller, respectively, compared to judgments from the CoP. Backward and forward displacement caused rectangles on the ground plane to be judged as larger and smaller in depth, respectively, compared to judgments from the CoP. Judgment biases were in the same direction as cue-based model predictions but of smaller magnitude. Displacement from the CoP had asymmetric effects on perceptual judgments, unlike model predictions. Perceptual distortion occurred with monocular cues alone but was exaggerated when binocular cues were added. The results are grounded in terms of practical implications for multiuser virtual environments.

In this paper, we describe an experiment designed to evaluate the effectiveness of three interfaces for surveillance or remote control using live 360-degree video feeds from a person or vehicle in the field. Video feeds are simulated using a game engine. While locating targets within a 3D terrain using a 2D 360-degree interface, participants indicated perceived egocentric directions to targets and later placed targets on an overhead view of the terrain. Interfaces were compared based on target finding and map placement performance. Results suggest 1) non-seamless interfaces with visual boundaries facilitate spatial understanding, 2) correct perception of self-to-object relationships is not correlated with understanding object-to-object relationships within the environment, and 3) increased video game experience corresponds with better spatial understanding of an environment observed in 360-degrees. This work can assist researchers of panoramic video systems in evaluating the optimal interface for observation and teleoperation of remote systems.

This study incorporated a dual-task paradigm, in which participants were asked to perform basic locomotion tasks with one of three interfaces while remembering a sequence of either spatial or verbal items. Interfaces varied in similarity to natural body movements. Stopping performance was compromised when concurrently remembering a spatial, but not verbal, sequence. Also users exhibited lower performance on spatial memory tasks while using more unnatural locomotion interfaces. These results confirm that semi-natural locomotion interfaces require spatial working memory resources and thus locomotion interfaces compete with ongoing spatial tasks, as opposed to those requiring verbal resources or general attention resources.

Stereoscopic depth cues improve depth perception and increase immersion within virtual environments (VEs). However, improper display of these cues can distort perceived distances and directions. Consider a multi-user VE, where all users view identical stereoscopic images regardless of physical location. In this scenario, cues are typically customized for one "leader" equipped with a head-tracking device. This user stands at the center of projection (CoP) and all other users ("followers") view the scene from other locations and receive improper depth cues. This paper examines perceived depth distortion when viewing stereoscopic VEs from follower perspectives and the impact of these distortions on collaborative spatial judgments. Pairs of participants made collaborative depth judgments of virtual shapes viewed from the CoP or after displacement forward or backward. Forward and backward displacement caused perceived depth compression and expansion, respectively, with greater compression than expansion. Furthermore, distortion was less than predicted by a ray-intersection model of stereo geometry. Collaboration times were significantly longer when participants stood at different locations compared to the same location, and increased with greater perceived depth discrepancy between the two viewing locations. These findings advance our understanding of spatial distortions in multi-user VEs, and suggest a strategy for reducing distortion.

The ability to judge heading (direction of travel) has been the focus of much research, but a role for perceived heading in steering has not been firmly established. Subjects steered down a road consisting of straight and curved segments and made heading judgments along the way. Heading judgments while traversing curved road segments were biased in the direction of the curve by up to 5° and position errors on the same curved roads were highly correlated with heading biases. This correlation was revealed by the simultaneous measurement of steering performance and perceived heading.