Characteristics of head-mounted displays and their effects on simulator sickness

A Study on Interaction of Gaze Pointer-Based User Interface in Mobile Virtual Reality Environment

This research proposes a gaze pointer-based user interface to provide user-oriented interaction suitable for the virtual reality environment on mobile platforms. For this purpose, a mobile platform-based three-dimensional interactive content is produced to test whether the proposed gaze pointer-based interface increases user satisfaction through the interactions in a virtual reality environment based on mobile platforms. The gaze pointer-based interface—the most common input method for mobile virtual reality content—is designed by considering four types: the visual field range, the feedback system, multi-dimensional information transfer, and background colors. The performance of the proposed gaze pointer-based interface is analyzed by conducting experiments on whether or not it offers motives for user interest, effects of enhanced immersion, provision of new experience, and convenience in operating content. In addition, it is verified whether any negative psychological factors, such as VR sickness, fatigue, difficulty of control, and discomfort in using contents are caused. Finally, through the survey experiment, this study confirmed that it is possible to design different ideal gaze pointer-based interface in mobile VR environment according to presence and convenience.

Assessing balance through the use of a low-cost head-mounted display in older adults: a pilot study

Introduction

As the population ages, the prevention of falls is an increasingly important public health problem. Balance assessment forms an important component of fall-prevention programs for older adults. The recent development of cost-effective and highly responsive virtual reality (VR) systems means new methods of balance assessment are feasible in a clinical setting. This proof-of-concept study made use of the submillimeter tracking built into modern VR head-mounted displays (VRHMDs) to assess balance through the use of visual–vestibular conflict. The objective of this study was to evaluate the validity, acceptability, and reliability of using a VRHMD to assess balance in older adults.

Materials and methods

Validity was assessed by comparing measurements from the VRHMD to measurements of postural sway from a force plate. Acceptability was assessed through the use of the Simulator Sickness Questionnaire pre- and postexposure to assess possible side effects of the visual–vestibular conflict. Reliability was assessed by measuring correlations between repeated measurements 1 week apart. Variables of possible importance that were found to be reliable (r≥0.9) between tests separated by a week were then tested for differences compared to a control group. Assessment was performed as a cross-sectional single-site community center-based study in 13 older adults (≥65 years old, 80.2±7.3 years old, 77% female, five at risk of falls, eight controls). The VR balance assessment consisted of four modules: a baseline module, a reaction module, a balance module, and a seated assessment.

Results

There was a significant difference in the rate at which participants with a risk of falls changed their tilt in the anteroposterior direction compared to the control group. Participants with a risk of falls changed their tilt in the anteroposterior direction at 0.7°/second vs 0.4°/second for those without a history of falls. No significant differences were found between pre/postassessment for oculomotor score or total Simulator Sickness Questionnaire score. Both the force plate and the head-mounted display balance-assessment system were able to detect differences between conditions meant to mask visual and proprioceptive information.

Conclusion

This VRHMD is both affordable and portable, causes minimal simulator sickness, and produces repeatable results that can be used to assess balance in older adults.

Manipulating Bodily Presence Affects Cross-Modal Spatial Attention: A Virtual-Reality-Based ERP Study

Earlier studies have revealed cross-modal visuo-tactile interactions in endogenous spatial attention. The current research used event-related potentials (ERPs) and virtual reality (VR) to identify how the visual cues of the perceiver’s body affect visuo-tactile interaction in endogenous spatial attention and at what point in time the effect takes place. A bimodal oddball task with lateralized tactile and visual stimuli was presented in two VR conditions, one with and one without visible hands, and one VR-free control with hands in view. Participants were required to silently count one type of stimulus and ignore all other stimuli presented in irrelevant modality or location. The presence of hands was found to modulate early and late components of somatosensory and visual evoked potentials. For sensory-perceptual stages, the presence of virtual or real hands was found to amplify attention-related negativity on the somatosensory N140 and cross-modal interaction in somatosensory and visual P200. For postperceptual stages, an amplified N200 component was obtained in somatosensory and visual evoked potentials, indicating increased response inhibition in response to non-target stimuli. The effect of somatosensory, but not visual, N200 enhanced when the virtual hands were present. The findings suggest that bodily presence affects sustained cross-modal spatial attention between vision and touch and that this effect is specifically present in ERPs related to early- and late-sensory processing, as well as response inhibition, but do not affect later attention and memory-related P3 activity. Finally, the experiments provide commeasurable scenarios for the estimation of the signal and noise ratio to quantify effects related to the use of a head mounted display (HMD). However, despite valid a-priori reasons for fearing signal interference due to a HMD, we observed no significant drop in the robustness of our ERP measurements.

Simulator Sickness and the Oculus Rift

The use of a commercial-off-the-shelf (COTS) head-mounted display (HMD) and its effects on simulator sickness (SS) was investigated in this preliminary study. Participants performed a navigation task and an observational task. Both of the tasks allowed participants to freely view the 360 degree dynamic three-dimensional (3D) virtual reality environment (VRE). We hypothesized that SS would increase over time participating in the VRE and that SS would be greater in the observational task as compared to the navigation task. SS ratings did increase over time; however, SS did not differ between the observational and navigation task. These findings suggested that SS is still a relevant factor to consider with COTS 3D HMD use.

Feasibility of a walking virtual reality system for rehabilitation: objective and subjective parameters

BACKGROUND

Even though virtual reality (VR) is increasingly used in rehabilitation, the implementation of walking navigation in VR still poses a technological challenge for current motion tracking systems. Different metaphors simulate locomotion without involving real gait kinematics, which can affect presence, orientation, spatial memory and cognition, and even performance. All these factors can dissuade their use in rehabilitation. We hypothesize that a marker-based head tracking solution would allow walking in VR with high sense of presence and without causing sickness. The objectives of this study were to determine the accuracy, the jitter, and the lag of the tracking system and its elicited sickness and presence in comparison of a CAVE system.

METHODS

The accuracy and the jitter around the working area at three different heights and the lag of the head tracking system were analyzed. In addition, 47 healthy subjects completed a search task that involved navigation in the walking VR system and in the CAVE system. Navigation was enabled by natural locomotion in the walking VR system and through a specific device in the CAVE system. An HMD was used as display in the walking VR system. After interacting with each system, subjects rated their sickness in a seven-point scale and their presence in the Slater-Usoh-Steed Questionnaire and a modified version of the Presence Questionnaire.

RESULTS

Better performance was registered at higher heights, where accuracy was less than 0.6 cm and the jitter was about 6 mm. The lag of the system was 120 ms. Participants reported that both systems caused similar low levels of sickness (about 2.4 over 7). However, ratings showed that the walking VR system elicited higher sense of presence than the CAVE system in both the Slater-Usoh-Steed Questionnaire (17.6 ± 0.3 vs 14.6 ± 0.6 over 21, respectively) and the modified Presence Questionnaire (107.4 ± 2.0 vs 93.5 ± 3.2 over 147, respectively).

CONCLUSIONS

The marker-based solution provided accurate, robust, and fast head tracking to allow navigation in the VR system by walking without causing relevant sickness and promoting higher sense of presence than CAVE systems, thus enabling natural walking in full-scale environments, which can enhance the ecological validity of VR-based rehabilitation applications.

The effect of viewing a virtual environment through a head-mounted display on balance

INTRODUCTION

In the next few years, several head-mounted displays (HMD) will be publicly released making virtual reality more accessible. HMD are expected to be widely popular at home for gaming but also in clinical settings, notably for training and rehabilitation. HMD can be used in both seated and standing positions; however, presently, the impact of HMD on balance remains largely unknown. It is therefore crucial to examine the impact of viewing a virtual environment through a HMD on standing balance.

OBJECTIVES

To compare static and dynamic balance in a virtual environment perceived through a HMD and the physical environment. The visual representation of the virtual environment was based on filmed image of the physical environment and was therefore highly similar.

DESIGN

This is an observational study in healthy adults.

RESULTS

No significant difference was observed between the two environments for static balance. However, dynamic balance was more perturbed in the virtual environment when compared to that of the physical environment.

CONCLUSIONS

HMD should be used with caution because of its detrimental impact on dynamic balance. Sensorimotor conflict possibly explains the impact of HMD on balance.

Reducing Visual Discomfort with HMDs Using Dynamic Depth of Field

Although head-mounted displays (HMDs) are ideal devices for personal viewing of immersive stereoscopic content, exposure to VR applications on them results in significant discomfort for the majority of people, with symptoms including eye fatigue, headaches, nausea, and sweating. A conflict between accommodation and vergence depth cues on stereoscopic displays is a significant cause of visual discomfort. This article describes the results of an evaluation used to judge the effectiveness of dynamic depth-of-field (DoF) blur in an effort to reduce discomfort caused by exposure to stereoscopic content on HMDs. Using a commercial game engine implementation, study participants report a reduction of visual discomfort on a simulator sickness questionnaire when DoF blurring is enabled. The study participants reported a decrease in symptom severity caused by HMD exposure, indicating that dynamic DoF can effectively reduce visual discomfort.

Alleviating simulator sickness with galvanic cutaneous stimulation

OBJECTIVE

In a driving simulation, we investigated the efficacy of galvanic cutaneous stimulation (GCS) provided during curves or intermittently during the whole circuit to mitigate simulator syndrome (SS).

BACKGROUND

The literature on how GCS decreases SS, although scarce, has demonstrated the effectiveness of this technique. Stimulation with this and similar techniques has usually been provided in curves or continuously during the whole circuit but never intermittently. This stimulation method could generate a continued activation of processes related to GCS mitigating SS.

METHOD

Fifteen drivers (8 men; mean age = 25.5 years) participated in this experiment. We compared the total scores of the Simulator Sickness Questionnaire (SSQ) across three stimulation conditions: (a) curve GCS condition, whereby GCS was provided in curves; (b) intermittent GCS condition, whereby GCS was provided intermittently during the whole circuit; and (c) no-stimulation condition, whereby no stimulation was provided (baseline condition).

RESULTS

The experimental outcomes revealed that GCS decreased SS in both the curve and intermittent stimulation conditions.

CONCLUSION

We provide evidence that GCS is an effective countermeasure to decrease SS. It could be applied indifferently in curves or intermittently during the whole circuit.

APPLICATION

For future interventions, we recommend the use of GCS to mitigate SS with similar intermittent stimulation programs. These programs have a crucial advantage as they are easily integrated into the simulator setup without the necessity of generating a complicated experimental design to stimulate during the curves.

Visually induced motion sickness can be alleviated by pleasant odors

Visually induced motion sickness (VIMS) is a common side effect in virtual environments and simulators. Several countermeasures against VIMS exist, but a reliable method to prevent or ease VIMS is unfortunately still missing. In the present study, we tested whether olfactory cues can alleviate VIMS. Sixty-two participants were exposed to a 15-min-long video showing a first-person-view bicycle ride that had successfully induced VIMS in previous studies. Participants were randomly assigned to one of three groups; the first group was exposed to a pleasant odor (rose) while watching the video, the second group was exposed to an unpleasant odor (leather), and the third group was not exposed to any odor. VIMS was measured using a verbal rating scale (0-20) and the Simulator Sickness Questionnaire. Results showed that only half of the participants who were exposed to the odor did notice it (n = 21), whereas the other half failed to detect the odor. However, among those participants who did notice the odor, the rose scent significantly reduced the severity of VIMS compared to the group that did not notice the odor. A moderate positive correlation between odor sensitivity and VIMS showed that participants with higher odor sensitivity also reported stronger VIMS. Our results demonstrate that olfaction can modulate VIMS and that a pleasant odor can potentially reduce VIMS. The relationship between olfactory perception, olfactory sensibility, and VIMS is discussed.

Pleasant music as a countermeasure against visually induced motion sickness

Visually induced motion sickness (VIMS) is a well-known side-effect in virtual environments or simulators. However, effective behavioral countermeasures against VIMS are still sparse. In this study, we tested whether music can reduce the severity of VIMS. Ninety-three volunteers were immersed in an approximately 14-minute-long video taken during a bicycle ride. Participants were randomly assigned to one of four experimental groups, either including relaxing music, neutral music, stressful music, or no music. Sickness scores were collected using the Fast Motion Sickness Scale and the Simulator Sickness Questionnaire. Results showed an overall trend for relaxing music to reduce the severity of VIMS. When factoring in the subjective pleasantness of the music, a significant reduction of VIMS occurred only when the presented music was perceived as pleasant, regardless of the music type. In addition, we found a gender effect with women reporting more sickness than men. We assume that the presentation of pleasant music can be an effective, low-cost, and easy-to-administer method to reduce VIMS.

Simultaneous neural and movement recording in large-scale immersive virtual environments

Virtual reality (VR) allows precise control and manipulation of rich, dynamic stimuli that, when coupled with on-line motion capture and neural monitoring, can provide a powerful means both of understanding brain behavioral relations in the high dimensional world and of assessing and treating a variety of neural disorders. Here we present a system that combines state-of-the-art, fully immersive, 3D, multi-modal VR with temporally aligned electroencephalographic (EEG) recordings. The VR system is dynamic and interactive across visual, auditory, and haptic interactions, providing sight, sound, touch, and force. Crucially, it does so with simultaneous EEG recordings while subjects actively move about a 20 × 20 ft² space. The overall end-to-end latency between real movement and its simulated movement in the VR is approximately 40 ms. Spatial precision of the various devices is on the order of millimeters. The temporal alignment with the neural recordings is accurate to within approximately 1 ms. This powerful combination of systems opens up a new window into brain-behavioral relations and a new means of assessment and rehabilitation of individuals with motor and other disorders.

Using virtual reality to assess user experience

OBJECTIVE

The aim of this article is to discuss how user experience (UX) evaluation can benefit from the use of virtual reality (VR).

BACKGROUND

UX is usually evaluated in laboratory settings. However, considering that UX occurs as a consequence of the interaction between the product, the user, and the context of use, the assessment of UX can benefit from a more ecological test setting. VR provides the means to develop realistic-looking virtual environments with the advantage of allowing greater control of the experimental conditions while granting good ecological validity.

METHOD

The methods used to evaluate UX, as well as their main limitations, are identified.The currentVR equipment and its potential applications (as well as its limitations and drawbacks) to overcome some of the limitations in the assessment of UX are highlighted.

RESULTS

The relevance of VR for UX studies is discussed, and a VR-based framework for evaluating UX is presented.

CONCLUSION

UX research may benefit from a VR-based methodology in the scopes of user research (e.g., assessment of users' expectations derived from their lifestyles) and human-product interaction (e.g., assessment of users' emotions since the first moment of contact with the product and then during the interaction).

APPLICATION

This article provides knowledge to researchers and professionals engaged in the design of technological interfaces about the usefulness of VR in the evaluation of UX.

Artificial horizon effects on motion sickness and performance

HYPOTHESIS

To investigate whether the projection of Earth-referenced scenes during provocative motion can alleviate motion sickness severity and prevent motion sickness-induced degradation of performance.

BACKGROUND

Exposure to unfamiliar motion patterns commonly results in motion sickness and decreased performance.

METHODS

Thirty subjects with moderate-to-severe motion sickness susceptibility were exposed to the recorded motion profile of a missile boat under moderate sea conditions in a 3-degrees-of-freedom ship motion simulator. During a 120-minute simulated voyage, the study participants were repeatedly put through a performance test battery and completed a motion sickness susceptibility questionnaire, while self-referenced and Earth-referenced visual scenes were projected inside the closed simulator cabin.

RESULTS

A significant decrease was found in the maximal motion sickness severity score, from 9.83 ± 9.77 (mean ± standard deviation) to 7.23 ± 7.14 (p < 0.03), when the visual display better approximated the full scale of the roll, pitch, and heave movements of the simulator. Although there was a significant decrease in sickness severity, substantial symptoms still persisted. Decision making, vision, concentration, memory, simple reasoning, and psychomotor skills all deteriorated under the motion conditions. However, no significant differences between the projection conditions could be found in the scores of any of the performance tests.

CONCLUSION

Visual information regarding the vessel's movement provided by an artificial horizon device might decrease motion sickness symptoms. However, although this device might be suitable for passive transportation, the continued deterioration in performance measures indicates that it provides no significant advantage for personnel engaged in the active operation of modern vessels.

The effect of apparent latency on simulator sickness while using a see-through helmet-mounted display: reducing apparent latency with predictive compensation

OBJECTIVE

The aim of this study was to determine the effect of head movement frequency and predictive compensation on (a) latency produced in a monocular see-through helmet-mounted display (HMD) test bed and (b) simulator sickness experienced by users wearing the HMD.

BACKGROUND

There is conflicting research regarding latency as a significant factor in the onset of simulator sickness. Predictive compensation has been shown to mitigate the magnitude of latency, but little is known about the extent of its effect on simulator sickness.

METHOD

A video camera recorded HMD and simulator imagery to accurately measure apparent latency produced at three head movement frequencies. Predictive compensation strategies were manipulated to measure the difference in apparent latency produced by the test bed in various conditions. Similar methodology was employed with human participants to measure simulator sickness experienced by users of this test bed.

RESULTS

In Experiment 1, apparent latency increased significantly as head movement frequency increased. Predictive compensation strategies significantly reduced apparent latency present in the test bed. In Experiment 2, predictive compensation significantly reduced the magnitude of simulator sickness.

CONCLUSION

Predictive compensation can be effectively implemented to reduce apparent latency, resulting in a lower magnitude of simulator sickness.

APPLICATION

Potential applications include HMD use in which head position is tracked and visual imagery is linked to head or body movement, such as in virtual and augmented reality systems, and is thus critical to functionality and performance.

A Study on the Possibility of Applying Subliminal Visual Cue for Guiding Subject’s Attention

This paper presents a new warning method for increasing drivers’ sensitivity for recognizing hazardous factors in the driving environment. The method is based on a subliminal effect. In this study, the presentation of a visual cue at a lower contrast ratio than that of the background scenery was investigated as subliminal visual information instead of flashing information quickly. This method was chosen in consideration of its use in real-world driving situations where changes in ambient brightness are among the biggest visual disturbances experienced by drivers. Accordingly, it is necessary to have amethod that is applicable in the context of dynamic changes in brightness. The results of many experiments performed with a threedimensional head-mounted display show that the response time for detecting a flashing mark tended to decrease when a subliminal mark was shown in advance. A priming effect is observed for subliminal visual information. This paper also proposes a scenario for implementing this method in real vehicles.