1. Abstract Background Virtual reality (VR) technologies that integrate with motion-base simulators (MBS) have the potential to accelerate personnel training and enhance workplace safety. Motion sickness on an MBS is a widespread problem with vast individual differences that are likely related to idiosyncrasies in estimates of head, body, and vehicle motions. When combined with head-mounted VR, we term the emergent symptoms ‘cybersickness’. Methods We conducted two experiments that evaluated cybersickness mitigations in an MBS. In Experiment 1 (N = 8), we tested the effectiveness of a light-touch body harness attached to a mobile-elevated work platform (MEWP) simulator during two nauseogenic VR tasks. In Experiment 2 (N = 14, 7 of whom completed Experiment 1), we tested the effectiveness of a dynamic field-of-view (dFOV) modifier that adaptively restricted the FOV for vehicle rotations in the same VR tasks. We gathered subjective sickness data and qualitative evaluations of the mitigations after the fact. Results We observed a reduced level of sickness in both Experiment 1 and 2 when mitigations were applied. In Experiment 1, the use of a harness led to a mild decrease in total cybersickness of between 3-11%, which was only significant for the nausea dimension. In Experiment 2, the use of dFOV imparted a large benefit to comfort, up to a 45% improvement. Both mitigations primarily improved comfort in a bumpy trench traversal task. Conclusions Cybersickness mitigations can help to deliver VR training for longer, and to more users. The type of content undertaken should be considered when employing new mitigations.

Cybersickness describes the nausea and discomfort that frequently emerges upon exposure to a virtual reality (VR) environment. The extent to which cybersickness leads to temporary constraints in cognitive functioning after VR exposure is a critical aspect of evaluating the risk to human safety where VR tasks are used for workforce training. Here, we examined whether VR exposure results in deteriorated cognitive spatial ability and attention, and if this possible deterioration is related to cybersickness. A standardized cognitive test battery consisting of Corsi blocks task (CBT), Manikin spatial task (MST), and color trails test (CTT-A and -B) was administered before and after participants were exposed to virtual reality (VR group), or engaged in interactive board games (control group). The performance of participants in CBT remained unchanged from pre-test to post-test in both groups, while performance in MST improved in the control and remained stable in VR group. Response times in CTT-A remained stable in the VR group but reduced significantly in the control group. Regarding CTT-B, participants from both groups became significantly faster in post-test. We did not observe any significant sex differences, or effects of past VR experience, across measures of cognitive performance or cybersickness. Crucially, no significant correlations were found between cognitive performance changes and cybersickness scores in any cases. The results provide encouragement for the use of VR in professional settings, suggesting that VR and cybersickness may minimally limit subsequent cognitive processing. However, it will be crucial to further examine the aftereffects in other cognitive functions.

The mechanism underlying cybersickness during virtual reality (VR) exposure is still poorly understood, although research has highlighted a causal role for visual-vestibular sensory conflict. Recently established methods for reducing cybersickness include galvanic vestibular stimulation (GVS) to mimic absent vestibular cues in VR, or vibration of the vestibular organs to add noise to the sensory modality. Here, we examined if applying noise to the vestibular system using noisy-current GVS also affects sickness severity in VR. Participants were exposed to one of two VR games that were classified as either moderate or intense with respect to their nauseogenic effects. The VR content lasted for 50 minutes and was broken down into 3 blocks: 30 minutes of gameplay during exposure to either noisy GVS (±1750 μA) or sham stimulation (0 μA), and 10 minutes of gameplay before and after this block. We characterized the effects of noisy GVS in terms of post-minus-pre-exposure cybersickness scores. For the intense VR content, we found a main effect of noisy vestibular stimulation. Participants reported lower cybersickness scores during and directly after exposure to GVS. However, this difference was quickly extinguished (∼3-6 min) after further exposure to VR, indicating that sensory adaptation did not persist after stimulation was terminated. In contrast, there were no differences between the sham and GVS group for the moderate VR content. The results show the potential for reducing cybersickness with simple non-invasive sensory stimulation. We discuss the prospect that noise-induced sensory re-weighting is responsible for the observed effects, and address other possible mechanisms.

Large-field optic flow generates the illusory percept of self-motion, termed ‘vection’. Smoother visual motion displays generate a more compelling subjective sense of vection and objective postural responses, as well as a greater sense of immersiveness for the user observing the visual display. Research suggests that the function linking frame rate and vection asymptotes at 60 frames per second (FPS), but previous studies have used only moderate frame rates that do not approach the limits of human perception. Here, we measure vection using subjective and objective (mean frequency and path length of postural centre-of-pressure (COP) excursions) responses following the presentation of high-contrast optic flow stimuli at slow and fast speeds and low and ultra-high frame rates. We achieve this using a novel rendering method implemented with a projector capable of sub-millisecond temporal resolution in order to simulate refresh rates ranging from very low (15 FPS) to ultra-high frame rates (480 FPS). The results suggest that subjective vection was experienced most strongly at 60 FPS. Below and above 60 FPS, subjective vection is generally weaker, shorter, and starts later, although this pattern varied slightly according to the speed of stimuli. For objective measures, while the frequency of postural sway was unaffected by frame rate, COP path length was greatest for 480 FPS stimuli. Together, our results support diminishing returns for vection above 60 FPS and provide insight into the use of high frame rate for enhancing the user experience in visual displays.

Immersive technologies, such as virtual and augmented reality, initially failed to live up to expectations, but have improved greatly, with many new head-worn displays and associated applications being released over the past few years. Unfortunately, 'cybersickness' remains as a common user problem that must be overcome if mass adoption is to be realized. This article evaluates the state of research on this problem, identifies challenges that must be addressed, and formulates an updated cybersickness research and development (R&D) agenda. The new agenda recommends prioritizing creation of powerful, lightweight, and untethered head-worn displays, reduction of visual latencies, standardization of symptom and aftereffect measurement, development of improved countermeasures, and improved understanding of the magnitude of the problem and its implications for job performance. Some of these priorities are unresolved problems from the original agenda which should get increased attention now that immersive technologies are proliferating widely. If the resulting R&D agenda is carefully executed, it should render cybersickness a challenge of the past and accelerate mass adoption of immersive technologies to enhance training, performance, and recreation.

Sensory dynamics can be re-shaped by environmental interaction, allowing adaptation to altered or unfamiliar conditions that would otherwise provoke challenges for the central nervous system. One such condition occurs in virtual reality, where sensory conflict is thought to induce cybersickness. Although the sensory re-weighting process is likely to underlie adaptation to cybersickness, evidence of a link between sensory re-weighting dynamics and cybersickness is rare. Here, we characterize the relationship between sensory re-weighting in a balance control task and cybersickness. Participants were exposed to visual oscillation while standing in tandem stance. The sway path length of the center of pressure (COP) was measured and averaged for each level of visual oscillation, and a ratio was computed between high and low oscillation magnitudes to reflect the relative contributions of multiple sensory sources of information concerning balance control. Results showed a significant relationship between the magnitude dependency of sway and common sub-scales of cybersickness: disorientation [r(21) = 0.45, p = 0.028] and oculomotor discomfort [r(21) = 0.45, p = 0.033]. We conclude that participants who reported less cybersickness were better-able to down-weight visual information at high magnitude oscillations, thus demonstrating a lower dependency between sway and visual magnitude. The results confirm the utility of balance control as an indicator of cybersickness, and support the role of multisensory re-weighting in determining an individual's tolerance to VR applications.

Virtual reality (VR) provides a valuable research tool for studying what occurs when sensorimotor feedback loops are manipulated. Here we measured whether exposure to a novel temporal relationship between action and sensory reaction in VR causes recalibration of time perception. We asked 31 participants to perform time perception tasks where the interval of a moving probe was reproduced using continuous or discrete motor methods. These time perception tasks were completed pre- and post-exposure to dynamic VR content in a block-counterbalanced order. One group of participants experienced a standard VR task ("normal-time"), while another group had their real-world movements coupled to the flow of time in the virtual space ("movement contingent time-flow; MCTF"). We expected this novel action-perception relationship to affect continuous motor time perception performance, but not discrete motor time perception. The results indicated duration-dependent recalibration specific to a motor task involving continuous movement such that the probe intervals were under-estimated by approximately 15% following exposure to VR with the MCTF manipulation. Control tasks in VR and non-VR settings produced similar results to those of the normal-time VR group, confirming the specificity of the MCTF manipulation. The findings provide valuable insights into the potential impact of VR on sensorimotor recalibration. Understanding this process will be valuable for the development and implementation of rehabilitation practices.

Depth-ambiguous point-light walkers are most frequently seen as facing-the-viewer (FTV). It has been argued that the FTV bias depends on recognising the stimulus as a person. Accordingly, reducing the social relevance of biological motion by presenting stimuli upside down has been shown to reduce FTV bias. Here, we replicated the experiment that reported this finding and added stick figure walkers to the task in order to assess the effect of explicit shape information on facing bias for inverted figures. We measured the FTV bias for upright and inverted stick figure walkers and point-light walkers presented in different azimuth orientations. Inversion of the stimuli did not reduce facing direction judgements to chance levels. In fact, we observed a significant facing away bias in the inverted stimulus conditions. In addition, we found no difference in the pattern of data between stick figure and point-light walkers. Although the results are broadly consistent with previous findings, we do not conclude that inverting biological motion simply negates the FTV bias; rather, inversion causes stimuli to be seen facing away from the viewer more often than not. The results support the interpretation that primarily low-level visual processes are responsible for the biases produced by both upright and inverted stimuli.

The user base of the virtual reality (VR) medium is growing, and many of these users will experience cybersickness. Accounting for the vast inter-individual variability in cybersickness forms a pivotal step in solving the issue. Most studies of cybersickness focus on a single factor (e.g., balance, sex, vection), while other contributors are overlooked. Here, we characterize the complex relationship between cybersickness and several indices of sensorimotor processing. In a single session, we conducted a battery of tests of balance control, vection responses, and vestibular sensitivity to self-motion. A principal components regression model, primarily composed of balance control measures during vection, significantly predicted 37% of the variability in cybersickness measures. We observed strong, inverse associations between measures of sway and cybersickness. The results reiterate that the relationship between balance control and cybersickness is anything but straightforward. We discuss other factors that may account for the remaining variance in cybersickness.