Cybersickness Abatement from Repeated Exposure to VR with Reduced Discomfort.

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.

Field of View Restriction and Snap Turning as Cybersickness Mitigation Tools.

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.

Distance Perception in Virtual Reality: A Meta-Analysis of the Effect of Head-Mounted Display Characteristics.

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.

Individual differences in teleporting through virtual environments.

Virtual reality (VR) allows users to walk to explore the virtual environment (VE), but this capability is constrained by real obstacles. Teleporting interfaces overcome this constraint by allowing users to select a position, and sometimes orientation, in the VE before being instantly transported without self-motion cues. This study investigated whether individual differences in navigation performance when teleporting correspond to characteristics of the individual, including spatial ability. Participants performed triangle completion (traverse two outbound path legs, then point to the path origin) within VEs differing in visual landmarks. Locomotion was accomplished using three interfaces: walking, partially concordant teleporting (teleport to change position, rotate the body to change orientation), and discordant teleporting (teleport to change position and orientation). A latent profile analysis identified three profiles of individuals: those who performed well overall and improved with landmarks, those who performed poorly without landmarks but improved when available, and those who performed poorly even with landmarks. Characteristics of individuals differed across profiles, including gender, self-reported spatial ability, mental rotation, and perspective-taking; but only perspective-taking significantly distinguished all three profiles. This work elucidates spatial cognitive correlates of navigation and provides a framework for identifying susceptibility to disorientation in VR. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Remote research on locomotion interfaces for virtual reality: Replication of a lab-based study on teleporting interfaces.

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 effect of water immersion on vection in virtual reality.

Research about vection (illusory self-motion) has investigated a wide range of sensory cues and employed various methods and equipment, including use of virtual reality (VR). However, there is currently no research in the field of vection on the impact of floating in water while experiencing VR. Aquatic immersion presents a new and interesting method to potentially enhance vection by reducing conflicting sensory information that is usually experienced when standing or sitting on a stable surface. This study compares vection, visually induced motion sickness, and presence among participants experiencing VR while standing on the ground or floating in water. Results show that vection was significantly enhanced for the participants in the Water condition, whose judgments of self-displacement were larger than those of participants in the Ground condition. No differences in visually induced motion sickness or presence were found between conditions. We discuss the implication of this new type of VR experience for the fields of VR and vection while also discussing future research questions that emerge from our findings.

Teleporting through virtual environments: Effects of path scale and environment scale on spatial updating.

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.

Spatial cognitive implications of teleporting through virtual environments.

Teleporting is a popular interface to allow virtual reality users to explore environments that are larger than the available walking space. When teleporting, the user positions a marker in the virtual environment and is instantly transported without any self-motion cues. Five experiments were designed to evaluate the spatial cognitive consequences of teleporting and to identify environmental cues that could mitigate those costs. Participants performed a triangle completion task by traversing 2 outbound path legs before pointing to the unmarked path origin. Locomotion was accomplished via walking or 2 common implementations of the teleporting interface distinguished by the concordance between movement of the body and movement through the virtual environment. In the partially concordant teleporting interface, participants teleported to translate (change position) but turned the body to rotate. In the discordant teleporting interface, participants teleported to translate and rotate. Across all 5 experiments, discordant teleporting produced larger errors than partially concordant teleporting which produced larger errors than walking, reflecting the importance of translational and rotational self-motion cues. Furthermore, geometric boundaries (room walls or a fence) were necessary to mitigate the spatial cognitive costs associated with teleporting, and landmarks were helpful only in the context of a geometric boundary. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Crowdsourcing image analysis for plant phenomics to generate ground truth data for machine learning.

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.

Selection of macroreference frames in spatial memory.

Spatial memories are often hierarchically organized with different regions of space represented in unique clusters within the hierarchy. Each cluster is thought to be organized around its own microreference frame selected during learning, whereas relationships between clusters are organized by a macroreference frame. Two experiments were conducted in order to better understand important characteristics of macroreference frames. Participants learned overlapping spatial layouts of objects within a room-sized environment before performing a perspective-taking task from memory. Of critical importance were between-layout judgments thought to reflect the macroreference frame. The results indicate that (1) macroreference frames characterize overlapping spatial layouts, (2) macroreference frames are used even when microreference frames are aligned with one another, and (3) macroreference frame selection depends on an interaction between the global macroaxis (defined by characteristics of the layout of all learned objects), the relational macroaxis (defined by characteristics of the two layouts being related on a perspective-taking trial), and the learning view. These results refine the current understanding of macroreference frames and document their broad role in spatial memory.

Social effects on reference frame selection.

The presence of another person in a spatial scene has been shown to induce spontaneous perspective taking. This investigation presents two experiments exploring whether the presence of another person affects reference frame selection when representing object locations in memory. Participants studied objects from one view and later performed judgments of relative direction, which tested retrieval of the remembered layout from several imagined perspectives. Without another person in the scene during learning, participants selected a reference frame aligned with the studied view. The mere presence of the experimenter at a different perspective during learning did not affect reference frame selection. Requiring participants to process object locations from the experimenter's view during learning led to the selection of a reference frame aligned with the experimenter. However, the same effect also occurred when participants processed object locations from the perspective of a wooden box. In sum, the presence of another person during learning did not affect reference frame selection, and participants adopted a nonegocentric reference frame whether the nonegocentric perspective was occupied by a person or an object.

Reference frames in spatial updating when body-based cues are absent.

The current study investigated the reference frame used in spatial updating when idiothetic cues to self-motion were minimized (desktop virtual reality). In Experiment 1, participants learned a layout of eight objects from a single perspective (learning heading) in a virtual environment. After learning, they were placed in the same virtual environment and used a keyboard to navigate to two of the learned objects (visible) before pointing to a third object (invisible). We manipulated participants' starting orientation (initial heading) and final orientation (final heading) before pointing, to examine the reference frame used in this task. We found that participants used the initial heading and the learning heading to establish reference directions. In Experiment 2, the procedure was almost the same as in Experiment 1 except that participants pointed to objects relative to an imagined heading that differed from their final heading in the virtual environment. In this case, pointing performance was only affected by alignment with the learning heading. We concluded that the initial heading played an important role in spatial updating without idiothetic cues, but the representation established at this heading was transient and affected by the interruption of spatial updating; the learning heading, on the other hand, corresponded to an enduring representation which was used consistently.

Optimal combination of environmental cues and path integration during navigation.

Navigation is influenced by body-based self-motion cues that are integrated over time, in a process known as path integration, as well as by environmental cues such as landmarks and room shape. In two experiments we explored whether humans combine path integration and environmental cues (Exp. 1: room shape; Exp. 2: room shape, single landmark, and multiple landmarks) to reduce response variability when returning to a previously visited location. Participants walked an outbound path in an immersive virtual environment before attempting to return to the path origin. Path integration and an environmental cue were both available during the outbound path, but experimental manipulations created single- and dual-cue conditions during the return path. The response variance when returning to the path origin was reduced when both cues were available, consistent with optimal integration predicted on the basis of Bayesian principles. The findings indicate that humans optimally integrate multiple spatial cues during navigation. Additionally, a large (but not a small) cue conflict caused participants to assign a higher weight to path integration than to environmental cues, despite the relatively greater precision afforded by the environmental cues.

Rescaling of perceived space transfers across virtual environments.

Research over the past 20 years has consistently shown that egocentric distance is underperceived in virtual environments (VEs) compared with real environments. In 2 experiments, judgments of object distance (Experiment 1) and object size (Experiment 2) improved after a brief period of walking through the VE with continuous visual feedback. Whereas improvement of blind-walking distance judgments could be attributable to recalibration of walking, improvement in perceived size is considered evidence for rescaling of perceived space, whereby perceived size and distance increased after walking interaction. Furthermore, improvements in judged distance and size transferred to a new VE. Distance judgments, but not size judgments, continued to improve after additional walking interaction in the new VE. These results have theoretical implications regarding the effects of walking interaction on perceived space, and practical implications regarding methods of improving perceived distance in VEs. (PsycINFO Database Record

Cue combination in human spatial navigation.

This project investigated the ways in which visual cues and bodily cues from self-motion are combined in spatial navigation. Participants completed a homing task in an immersive virtual environment. In Experiments 1A and 1B, the reliability of visual cues and self-motion cues was manipulated independently and within-participants. Results showed that participants weighted visual cues and self-motion cues based on their relative reliability and integrated these two cue types optimally or near-optimally according to Bayesian principles under most conditions. In Experiment 2, the stability of visual cues was manipulated across trials. Results indicated that cue instability affected cue weights indirectly by influencing cue reliability. Experiment 3 was designed to mislead participants about cue reliability by providing distorted feedback on the accuracy of their performance. Participants received feedback that their performance with visual cues was better and that their performance with self-motion cues was worse than it actually was or received the inverse feedback. Positive feedback on the accuracy of performance with a given cue improved the relative precision of performance with that cue. Bayesian principles still held for the most part. Experiment 4 examined the relations among the variability of performance, rated confidence in performance, cue weights, and spatial abilities. Participants took part in the homing task over two days and rated confidence in their performance after every trial. Cue relative confidence and cue relative reliability had unique contributions to observed cue weights. The variability of performance was less stable than rated confidence over time. Participants with higher mental rotation scores performed relatively better with self-motion cues than visual cues. Across all four experiments, consistent correlations were found between observed weights assigned to cues and relative reliability of cues, demonstrating that the cue-weighting process followed Bayesian principles. Results also pointed to the important role of subjective evaluation of performance in the cue-weighting process and led to a new conceptualization of cue reliability in human spatial navigation.

Walking through a virtual environment improves perceived size within and beyond the walked space.

Distances tend to be underperceived in virtual environments (VEs) by up to 50%, whereas distances tend to be perceived accurately in the real world. Previous work has shown that allowing participants to interact with the VE while receiving continual visual feedback can reduce this underperception. Judgments of virtual object size have been used to measure whether this improvement is due to the rescaling of perceived space, but there is disagreement within the literature as to whether judgments of object size benefit from interaction with feedback. This study contributes to that discussion by employing a more natural measure of object size. We also examined whether any improvement in virtual distance perception was limited to the space used for interaction (1-5 m) or extended beyond (7-11 m). The results indicated that object size judgments do benefit from interaction with the VE, and that this benefit extends to distances beyond the explored space.

Frontal extents in virtual environments are not immune to underperception.

Distance is commonly underperceived by up to 50 % in virtual environments (VEs), in contrast to relatively accurate real world judgments. Experiments reported by Geuss, Stefanucci, Creem-Regehr, and Thompson (Journal of Experimental Psychology: Human Perception and Performance, 38, 1242-1253, 2012) indicate that the exocentric distance separating two objects in a VE is underperceived when the objects are oriented in the sagittal plane (depth extents), but veridically perceived when oriented in a frontoparallel plane (frontal extents). The authors conclude that "distance underestimation in the [VE] generalizes to intervals in the depth plane, but not to intervals in the frontal plane." The current experiment evaluated an alternative hypothesis that the accurate judgments of frontal extents reported by Geuss et al. were due to a fortunate balance of underperception caused by the VE and overperception of frontal relative to depth extents. Participants judged frontal and depth extents in the classroom VE used by Geuss et al. and in a sparser VE containing only a grass-covered ground plane. Judgments in the classroom VE replicated findings by Geuss et al., but judgments in the grass VE show underperception of both depth and frontal extents, indicating that frontal extents are not immune to underperception in VEs.

Bias in Human Path Integration Is Predicted by Properties of Grid Cells.

Accurate wayfinding is essential to the survival of many animal species and requires the ability to maintain spatial orientation during locomotion. One of the ways that humans and other animals stay spatially oriented is through path integration, which operates by integrating self-motion cues over time, providing information about total displacement from a starting point. The neural substrate of path integration in mammals may exist in grid cells, which are found in dorsomedial entorhinal cortex and presubiculum and parasubiculum in rats. Grid cells have also been found in mice, bats, and monkeys, and signatures of grid cell activity have been observed in humans. We demonstrate that distance estimation by humans during path integration is sensitive to geometric deformations of a familiar environment and show that patterns of path integration error are predicted qualitatively by a model in which locations in the environment are represented in the brain as phases of arrays of grid cells with unique periods and decoded by the inverse mapping from phases to locations. The periods of these grid networks are assumed to expand and contract in response to expansions and contractions of a familiar environment. Biases in distance estimation occur when the periods of the encoding and decoding grids differ. Our findings explicate the way in which grid cells could function in human path integration.

Retrieval enhances route knowledge acquisition, but only when movement errors are prevented.

Studies of the testing effect have shown that retrieval significantly improves learning. However, most of these studies have been restricted to simple types of declarative verbal knowledge. Five experiments were designed to explore whether testing improves acquisition of route knowledge, which has a procedural component consisting of actions to be performed at decision points (Golledge, 1991). Participants learned a route through a series of connected rooms in a virtual building. Each room contained multiple doors, only one of which led to the next room. During encoding, participants were shown the correct sequence of doors in a manner similar to global positioning system (GPS) navigation guidance. During subsequent exposures to the route, participants were either shown the correct sequence again or had to recall the sequence from memory. Participants later completed a final test in which they traversed the route without guidance or feedback. Testing improved route memory compared to studying, but only when participants were given feedback about the correct door prior to moving through the room. When feedback occurred after moving to an incorrect door, testing resulted in worse performance compared to studying. These findings parallel work on errorless learning, in which procedural skills are acquired more quickly when errors are minimized during learning.

Recalibration of perceived distance in virtual environments occurs rapidly and transfers asymmetrically across scale.

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.