[Evaluation of semicircular canal and otolith graviceptive pathway function in patients diagnosed with motion sickness disorder based on the diagnostic criteria of the Bárány society]

Objective: To investigate the altered function of the semicircular canal and otolith graviceptive pathway in patients diagnosed with motion sickness disorder (MSD) based on the diagnostic criteria of the Bárány society, and explore its relevance to the pathogenesis of MSD. Methods: This is a case-control study. Twenty patients with MSD and age-and sex-matched healthy controls without a history of MSD from the Department of Neurology of Aerospace Center Hospital between March and August 2022 were recruited. All subjects completed the motion sickness susceptibility questionnaire-short version (MSSQ-short) and the motion sickness assessment questionnaire (MSAQ). Canal function was evaluated using caloric stimulation test and video head impulse test (vHIT), and subjective visual vertical/horizontal (SVV/SVH) and vestibular evoked myogenic potential (VEMP) were employed to assess otolith graviceptive function. Differences in vestibular function and correlations between the two groups were analyzed. Results: Each group consisted of 20 cases (9 males and 11 females). The mean age of the MSD and control groups was (26.9±3.9) years and (27.0±3.4) years, respectively. The scores of MSSQ-short [27.0 (22.5, 38.8) vs 1.2 (0, 3.2), P<0.001] and MSAQ [70.1 (54.5, 78.1) vs 11.8 (11.1, 13.9), P<0.001] were significantly higher in the MSD group compared with those of the control group. Evaluation of canal function revealed a significantly higher incidence of caloric stimulation intolerance in MSD patients (60.0%, 12/20) compared with that of the control group (20.0%, 4/20) (P=0.010). Evaluation of otolith graviceptive pathway indicated no significant difference in SVV, SVH and cervical VEMP (cVEMP) abnormality rates between the two groups (all P>0.05). The ocular VEMP (oVEMP) abnormality rate was significantly higher in the MSD group (55.0%, 11/20) than that of the control group (10.0%, 2/20) (P=0.002), with a delayed P1-wave latency compared with the control group [(18.4±1.2) ms vs (17.6±0.8) ms, P=0.018]. Further correlation analysis revealed that P1-wave latency in oVEMP was positively correlated with MSSQ-short (r=0.486, P=0.002) and MSAQ (r=0.391, P=0.015) scores, and duration of caloric intolerance symptoms (r=0.377, P=0.004). Conclusion: The presence of hypersensitivity to caloric stimulation and delayed latency of otolith function in patients with MSD suggests a "separation" between semicircular canal and otolithic function, which may be related to sensory conflict.

Investigating cortical activity during cybersickness by fNIRS

This study investigated brain responses during cybersickness in healthy adults using functional near-infrared spectroscopy (fNIRS). Thirty participants wore a head-mounted display and observed a virtual roller coaster scene that induced cybersickness. Cortical activation during the virtual roller coaster task was measured using fNIRS. Cybersickness symptoms were evaluated using a Simulator Sickness Questionnaire (SSQ) administered after the virtual rollercoaster. Pearson correlations were performed for cybersickness symptoms and the beta coefficients of hemodynamic responses. The group analysis of oxyhemoglobin (HbO) and total hemoglobin (HbT) levels revealed deactivation in the bilateral angular gyrus during cybersickness. In the Pearson correlation analyses, the HbO and HbT beta coefficients in the bilateral angular gyrus had a significant positive correlation with the total SSQ and disorientation. These results indicated that the angular gyrus was associated with cybersickness. These findings suggest that the hemodynamic response in the angular gyrus could be a biomarker for evaluating cybersickness symptoms.

The role of vision in sensory integration models for predicting motion perception and sickness

Users of automated vehicles will engage in other activities and take their eyes off the road, making them prone to motion sickness. To resolve this, the current paper validates models predicting sickness in response to motion and visual conditions. We validate published models of vestibular and visual sensory integration that have been used for predicting motion sickness through sensory conflict. We use naturalistic driving data and laboratory motion (and vection) paradigms, such as sinusoidal translation and rotation at different frequencies, Earth-Vertical Axis Rotation, Off-Vertical Axis Rotation, Centrifugation, Somatogravic Illusion, and Pseudo-Coriolis, to evaluate different models for both motion perception and motion sickness. We investigate the effects of visual motion perception in terms of rotational velocity (visual flow) and verticality. According to our findings, the SVCI model, a 6DOF model based on the Subjective Vertical Conflict (SVC) theory, with visual rotational velocity input is effective at estimating motion sickness. However, it does not correctly replicate motion perception in paradigms such as roll-tilt perception during centrifuge, pitch perception during somatogravic illusion, and pitch perception during pseudo-Coriolis motions. On the other hand, the Multi-Sensory Observer Model (MSOM) accurately models motion perception in all considered paradigms, but does not effectively capture the frequency sensitivity of motion sickness, and the effects of vision on sickness. For both models (SVCI and MSOM), the visual perception of rotational velocity strongly affects sickness and perception. Visual verticality perception does not (yet) contribute to sickness prediction, and contributes to perception prediction only for the somatogravic illusion. In conclusion, the SVCI model with visual rotation velocity feedback is the current preferred option to design vehicle control algorithms for motion sickness reduction, while the MSOM best predicts perception. A unified model that jointly captures perception and motion sickness remains to be developed.

Relationship between Car-Sickness Susceptibility and Postural Activity: Could the Re-Weighting Strategy between Signals from Different Body Sensors Be an Underlying Factor?

Postural control characteristics have been proposed as a predictor of Motion Sickness (MS). However, postural adaptation to sensory environment changes may also be critical for MS susceptibility. In order to address this issue, a postural paradigm was used where accurate orientation information from body sensors could be lost and restored, allowing us to infer sensory re-weighting dynamics from postural oscillation spectra in relation to car-sickness susceptibility. Seventy-one participants were standing on a platform (eyes closed) alternating from static phases (proprioceptive and vestibular sensors providing reliable orientation cues) to sway referenced to the ankle-angle phases (proprioceptive sensors providing unreliable orientation cues). The power spectrum density (PSD) on a 10 s sliding window was computed from the antero-posterior displacement of the center of pressure. Energy ratios (ERs) between the high (0.7-1.3 Hz) and low (0.1-0.7 Hz) frequency bands of these PSDs were computed on key time windows. Results showed no difference between MS and non-MS participants following loss of relevant ankle proprioception. However, the reintroduction of reliable ankle signals led, for the non-MS participants, to an increase of the ER originating from a previously up-weighted vestibular information during the sway-referenced situation. This suggests inter-individual differences in re-weighting dynamics in relation to car-sickness susceptibility.

Potential factors contributing to observed sex differences in virtual-reality-induced sickness

Virtual reality (VR) technology has been widely adopted for several professional and recreational applications. Despite rapid innovation in hardware and software, one of the long prevailing issues for end users of VR is the experience of VR sickness. Females experience stronger VR sickness compared to males, and previous research has linked susceptibility to VR sickness to the menstrual cycle (Munafo et al., Exp Brain Res 235(3):889-901). Here we investigated the female versus male experience in VR sickness while playing an immersive VR game, comparing days of the menstrual cycle when hormones peak: day 15 (ovulation-peak estrogen) and day 22 (mid-luteal phase-peak progesterone). We found that immersion duration was greater in the second session than the first, and discomfort was lessened, suggesting a powerful adaptation with repeated exposure. Due to the estrogen levels changing along with the exposure, there was no clear independent impact of that; note, though, that there was a significant difference between self-report and physiological measures implying that GSR is potentially an unreliable measure of motion sickness. Although prior work found a delay over 2 days between session would not allow adaptation and habituation to reduce VR sickness susceptibility, we found that a week delay has potential success.

Differentiating Meniere's Disease and Vestibular Migraine: Insights from Gadolinium-Enhanced Magnetic Resonance Imaging and Clinical Features

OBJECTIVE

To explore the predictive factors between Meniere's disease (MD) and vestibular migraine (VM) by Gadolinium-enhanced Magnetic resonance imaging (MRI) of the inner ear and Clinical Features.

METHODS

Eighty-seven patients (50 MD and 37 VM) underwent intratympanic injection of gadolinium and MRI was performed 24 h later. All patients underwent pure tone audiometry and caloric tests.

RESULTS

In the MD group, 46 (92%) of 50 patients developed endolymphatic hydrops, although only 2 (5.4%) in the vestibular migraine (VM) group had positive results groups (p < 0.001). The incidence of migraine was 14% in the MD group and 67.7% in the VM group (p < 0.001). Multivariate logistic regression of the two groups of patients indicated that the greater the sum of the maximum slow phase velocity (SPV) of the ipsilateral ear, the higher the risk of VM occurrence (p = 0.009). The incidence of carsickness was positively correlated with the incidence of VM (p < 0.001) and asymmetric hearing loss (AHL) was negatively correlated with the diagnosis of VM (p = 0.045).

CONCLUSION

Gadolinium-enhanced MRI of the inner ear is helpful for the differential diagnosis of VM and MD. Carsickness, decreased AHL, and increased Sum of the maximum SPV in the ipsilateral side (SSPVI) may act as diagnostic predictors of VM.

LEVEL OF EVIDENCE

3 Laryngoscope, 134:426-432, 2024.

A Systematic Review of Immersive Virtual Reality for Nontechnical Skills Training in Surgery

OBJECTIVE

Immersive virtual reality (IVR) can be utilized to provide low cost and easily accessible simulation on all aspects of surgical education. In addition to technical skills training in surgery, IVR simulation has been utilized for nontechnical skills training in domains such as clinical decision-making and pre-operative planning. This systematic review examines the current literature on the effectiveness of IVR for nontechnical skill acquisition in surgical education.

DESIGN

A literature search was performed using MEDLINE, EMBASE, and Web of Science for primary studies published between January 1, 1995 and February 9, 2022. Four reviewers screened titles, abstracts, full texts, extracted data, and analyzed included studies to answer 5 key questions: How is IVR being utilized in nontechnical skills surgical education? What is the methodological quality of studies? What technologies are being utilized? What metrics are reported? What are the findings of these studies?

RESULTS

The literature search yielded 2340 citations, with 12 articles included for qualitative synthesis. Of included articles, 33% focused on clinical decision-making and 67% on anatomy/pre-operative planning. Motion sickness was a recorded metric in 25% of studies, with an aggregate incidence of 13% (11/87). An application score was reported in 33% and time to completion in 16.7%. A commercially developed application was utilized in 25%, while 75% employed a noncommercial application. The Oculus Rift was used in 41.7% of studies, HTC Vive in 25%, Samsung Gear in 16.7% of studies, Google Daydream in 8%, and 1 study did not report. The mean Medical Education Research Quality Instrument (MERSQI) score was 10.3 ± 2.3 (out of 18). In all studies researching clinical decision-making, participants preferred IVR to conventional teaching methods and in a nonrandomized control study it was found to be more effective. Averaged across all studies, mean scores were 4.33 for enjoyment, 4.16 for utility, 4.11 for usability, and 3.73 for immersion on a 5-point Likert scale.

CONCLUSIONS

The IVR nontechnical skills applications for surgical education are designed for clinical decision-making or anatomy/pre-operative planning. These applications are primarily noncommercially produced and rely upon a diverse array of HMDs for content delivery, suggesting that development is primarily coming from within academia and still without clarity on optimal utilization of the technology. Excitingly, users find these applications to be immersive, enjoyable, usable, and of utility in learning. Although a few studies suggest that IVR is additive or superior to conventional teaching or imaging methods, the data is mixed and derived from studies with weak design. Motion sickness with IVR remains a complication of IVR use needing further study to determine the cause and means of mitigation.

Using Nonlinear Kinematic Parameters as a Means of Predicting Motion Sickness in Real-Time in Virtual Environments

OBJECTIVE

This article presents two studies (one simulation and one pilot) that assess a custom computer algorithm designed to predict motion sickness in real-time.

BACKGROUND

Virtual reality has a wide range of applications; however, many users experience visually induced motion sickness. Previous research has demonstrated that changes in kinematic (behavioral) parameters are predictive of motion sickness. However, there has not been research demonstrating that these measures can be utilized in real-time applications.

METHOD

Two studies were performed to assess an algorithm designed to predict motion sickness in real-time. Study 1 was a simulation study that used data from Smart et al. (2014). Study 2 employed the algorithm on 28 new participants' motion while exposed to virtual motion.

RESULTS

Study 1 revealed that the algorithm was able to classify motion sick participants with 100% accuracy. Study 2 revealed that the algorithm could predict if a participant would become motion sick with 57% accuracy.

CONCLUSION

The results of the present study suggest that the motion sickness prediction algorithm can predict if an individual will experience motion sickness but needs further refinement to improve performance.

APPLICATION

The algorithm could be used for a wide array of VR devices to predict likelihood of motion sickness with enough time to intervene.

Virtual reality as a countermeasure for astronaut motion sickness during simulated post-flight water landings

Entry motion sickness (EMS) affects crewmembers upon return to Earth following extended adaptation to microgravity. Anticholinergic pharmaceuticals (e.g., Meclizine) are often taken prior to landing; however, they have operationally adverse side effects (e.g., drowsiness). There is a need to develop non-pharmaceutical countermeasures to EMS. We assessed the efficacy of a technological countermeasure providing external visual cues following splashdown, where otherwise only nauseogenic internal cabin visual references are available. Our countermeasure provided motion-congruent visual cues of an Earth-fixed scene in virtual reality, which was compared to a control condition with a head-fixed fixation point in virtual reality in a between-subject design with 15 subjects in each group. We tested the countermeasure's effectiveness at mitigating motion sickness symptoms at the end of a ground-based reentry analog: approximately 1 h of 2Gx centrifugation followed by up to 1 h of wave-like motion. Secondarily, we explored differences in vestibular-mediated balance performance between the two conditions. While Motion Sickness Questionnaire outcomes did not differ detectably between groups, we found significantly better survival rates (with dropout dictated by reporting moderate nausea consecutively over 2 min) in the visual countermeasure group than the control group (79% survival vs. 33%, t(14) = 2.50, p = 0.027). Following the reentry analogs, subjects demonstrated significantly higher sway prior to recovery (p = 0.0004), which did not differ between control and countermeasure groups. These results imply that providing motion-congruent visual cues may be an effective mean for curbing the development of moderate nausea and increasing comfort following future space missions.

Vestibular CCK signaling drives motion sickness-like behavior in mice

Travel can induce motion sickness (MS) in susceptible individuals. MS is an evolutionary conserved mechanism caused by mismatches between motion-related sensory information and past visual and motion memory, triggering a malaise accompanied by hypolocomotion, hypothermia, hypophagia, and nausea. Vestibular nuclei (VN) are critical for the processing of movement input from the inner ear. Motion-induced activation of VN neurons recapitulates MS-related signs. However, the genetic identity of VN neurons mediating MS-related autonomic and aversive responses remains unknown. Here, we identify a central role of cholecystokinin (CCK)-expressing VN neurons in motion-induced malaise. Moreover, we show that CCK VN inputs onto the parabrachial nucleus activate Calca-expressing neurons and are sufficient to establish avoidance to novel food, which is prevented by CCK-A receptor antagonism. These observations provide greater insight into the neurobiological regulation of MS by identifying the neural substrates of MS and providing potential targets for treatment.

Beyond the Eye: Multisensory Contributions to the Sensation of Illusory Self-Motion (Vection)

Vection is typically defined as the embodied illusion of self-motion in the absence of real physical movement through space. Vection can occur in real-life situations (e.g., 'train illusion') and in virtual environments and simulators. The vast majority of vection research focuses on vection caused by visual stimulation. Even though visually induced vection is arguably the most compelling type of vection, the role of nonvisual sensory inputs, such as auditory, biomechanical, tactile, and vestibular cues, have recently gained more attention. Non-visual cues can play an important role in inducing vection in two ways. First, nonvisual cues can affect the occurrence and strength of vection when added to corresponding visual information. Second, nonvisual cues can also elicit vection in the absence of visual information, for instance when observers are blindfolded or tested in darkness. The present paper provides a narrative review of the literature on multimodal contributions to vection. We will discuss both the theoretical and applied relevance of multisensory processing as related to the experience of vection and provide design considerations on how to enhance vection in various contexts.

Video head impulse and suppression head impulse test in vestibular migraine

BACKGROUND

Vestibular Migraine (VM) is a frequent cause of recurrent spontaneous vertigo. While some report a normal Video Head Impulse Test (vHIT) in VM, others observed abnormal results on this test. Whether or not methodological discrepancies could be the cause of these differences is not known. There are 2 vHIT methods: subjects fixating an earth-fixed target (HIMP paradigm) or a head-fixed target, the suppression head impulse test (SHIMP paradigm).

OBJECTIVES

The present study aimed to compare VM patients against healthy controls on both HIMP and SHIMP in order to unravel any differences between them.

METHODS

Forty-eight VM patients and 27 healthy controls tested with both the HIMP and SHIMP paradigm. Results: Our 48 VM patients showed mean VOR normal range gains in both the HIMP and SHIMP paradigms, although there were some VOR impairments in individual semicircular SCCs. VM patients with motion sickness had lower horizontal VOR gain than those without motion sickness, with the HIMP, but not the SHIMP paradigm.

CONCLUSION

VM patients have normal VOR gain with either vHIT paradigm.

SIGNIFICANCE

The clinical significance of this observation is that a definitely abnormal vHIT with either method is unlikely to be due to vestibular migraine and an alternative diagnosis should be sought.

A computational model of motion sickness dynamics during passive self-motion in the dark

Predicting the time course of motion sickness symptoms enables the evaluation of provocative stimuli and the development of countermeasures for reducing symptom severity. In pursuit of this goal, we present an observer-driven model of motion sickness for passive motions in the dark. Constructed in two stages, this model predicts motion sickness symptoms by bridging sensory conflict (i.e., differences between actual and expected sensory signals) arising from the observer model of spatial orientation perception (stage 1) to Oman's model of motion sickness symptom dynamics (stage 2; presented in 1982 and 1990) through a proposed "Normalized innovation squared" statistic. The model outputs the expected temporal development of human motion sickness symptom magnitudes (mapped to the Misery Scale) at a population level, due to arbitrary, 6-degree-of-freedom, self-motion stimuli. We trained model parameters using individual subject responses collected during fore-aft translations and off-vertical axis of rotation motions. Improving on prior efforts, we only used datasets with experimental conditions congruent with the perceptual stage (i.e., adequately provided passive motions without visual cues) to inform the model. We assessed model performance by predicting an unseen validation dataset, producing a Q2 value of 0.86. Demonstrating this model's broad applicability, we formulate predictions for a host of stimuli, including translations, earth-vertical rotations, and altered gravity, and we provide our implementation for other users. Finally, to guide future research efforts, we suggest how to rigorously advance this model (e.g., incorporating visual cues, active motion, responses to motion of different frequency, etc.).

Layperson Physiological Tolerance and Operational Performance in Centrifuge-Simulated Spaceflight

INTRODUCTION: Prior study has indicated that individuals of varied age, medical history, and limited-to-no experience tolerate spaceflight conditions. We sought to expand upon the understanding of layperson response to hypergravity conditions expected in commercial spaceflight by exposing subjects, following minimal training, to centrifuge-simulated, high-fidelity commercial spaceflight profiles. We further explored how these individuals perform in simulated operational activities during and following hypergravity.METHODS: Volunteer subjects participated in up to five centrifuge runs (maximum +4.0 Gz, +4.5 Gx, 6.1 G resultant; onset rate <0.5 Gz · s-1, ≤1 Gx · s-1). Profiles included two winged spacecraft simulations with sequential and combined +Gx/+Gz and two capsule simulations representing nominal +Gx launch and reentry. The final profile simulated a capsule launch abort, with a more dynamic cycling of +Gx exposures and oscillatory multi-axis exposures simulating parachutes and water motion. Touchscreen tablets were used to administer pattern-replication tasks during and after profiles.RESULTS: A total of 46 subjects participated, including 4 diabetics and 9 with cardiac disease. There was increased frequency of motion sickness, subjectively associated with capsule-type profiles, and increased termination of participation compared to prior studies. There was no association between medical history, age, sex, or motion sickness history and tolerance or noncompletion. Tablet test errors were common; accuracy and time to completion were associated with age. There was no association between any time metric or accuracy and sex.DISCUSSION: This study improves understanding of layperson tolerance in commercial spaceflight analog conditions, and the capsular profiles broaden the applicability of the findings. The frequency of task errors highlights the potential for mistakes in operational activities when performed by laypersons.Blue RS, Ong KM, Ray K, Menon A, Mateus J, Auñón-Chancellor S, Shah R, Powers W. Layperson physiological tolerance and operational performance in centrifuge-simulated spaceflight. Aerosp Med Hum Perform. 2023; 94(8):584-595.

Which video technology brings the higher cognitive burden and motion sickness in laparoscopic colorectal surgery: 3D, 2D-4 K or 3D-4 K? a propensity score study

BACKGROUND

Technological development has offered laparoscopic colorectal surgeons new video systems to improve depth perception and perform difficult task in limited space. The aim of this study was to assess the cognitive burden and motion sickness for surgeons during 3D, 2D-4 K or 3D-4 K laparoscopic colorectal procedures and to report post-operative data with the different video systems employed.

METHODS

Patients were assigned to either 3D, 2D-4 K or 3D-4 K video and two questionnaires (Simulator Sickness Questionnaire-SSQ- and NASA Task Load Index -TLX) were used during elective laparoscopic colorectal resections (October 2020-August 2022) from two operating surgeons. Short-term results of the operations performed with the three different video systems were also analyzed.

RESULTS

A total of 113 consecutive patients were included: 41 (36%) in the 3D Group (A), 46 (41%) in the 3D-4 K Group and 26 (23%) in the 2D-4 K Group (C). Weighted and adjusted regression models showed no significant difference in cognitive load amongst the surgeons in the three groups of video systems when using the NASA-TLX. An increased risk for slight/moderate general discomfort and eyestrain in the 3D-4 K group compared with 2D-4 K group (OR = 3.5; p = 0.0057 and OR = 2.8; p = 0.0096, respectively) was observed. Further, slight/moderate difficulty focusing was lower in both 3D and 3D-4 K groups compared with 2D-4 K group (OR = 0.4; p = 0.0124 and OR = 0.5; p = 0.0341, respectively), and higher in the 3D-4 K group compared with 3D group (OR = 2.6; p = 0.0124). Patient population characteristics, operative time, post-operative staging, complication rate and length of stay were similar in the three groups of patients.

CONCLUSIONS

3D and 3D-4 K systems, when compared with 2D-4 K video technology, have a higher risk for slight/moderate general discomfort and eyestrain, but show lower difficulty focusing. Short post-operative outcomes do not differ, whichever imaging system is used.

Subjective Visual Vertical test with the 3D virtual reality system: effective factors and cybersickness

BACKGROUND

3D Virtual Reality (VR) offers new opportunities in vestibular science. It also presents new challenges and problems.

AIMS/OBJECTIVES

The study aimed to evaluate the effective factors in the 3D VR Subjective Visual Vertical (SVV) test and the impact of cybersickness on the test results.

MATERIAL AND METHODS

The effect of the foam surface, head position in the yaw axis, moving background, and arm position holding the controller was tested. Cybersickness was evaluated using the Simulator Sickness Questionnaire (SSQ).

RESULTS

The head position and controller holding style significantly affected the results. The foam surface and the moving background did not have a significant effect. Although 61.4% of the patients fell into the bad category according to the symptoms of the SSQ score, cybersickness did not significantly affect the SVV results.

CONCLUSIONS AND SIGNIFICANCE

In 3D VR SVV, additional factors should be considered: the headset's weight, head position, and how we hold the controller. The A-effect emerged when the head was 45 degrees turned on the yaw axis. A significant shift was detected in the test, with the arm holding the controller at 90 degrees. Most subjects felt cybersickness at a considerable level. Cybersickness should always be taken into account in VR when planning new applications.

A METHOD FOR IMPROVING THE PROFESSIONAL PERFORMANCE AND RELIABILITY OF PERSONS DRIVING HIGH-SPEED VEHICLES

Recently, due to the emergence of a variety of modifications of air, land, water vehicles and an increase in their speed and maneuverability, the number of people with severe manifestations of motion sickness has also increased. The relevance of this problem is dictated by the fact that, despite significant achievements in the field of preventive medicine, a significant number of people prone to motion sickness have been observed to date. Thus, among persons using land modes of transport, the percentage of sick people reaches 15.0%, air modes 20.0%, while using water modes of transport, the number of sick people reaches 30.0%. The significance of this problem is dictated by the fact that the psycho-physiological capabilities of our body do not keep pace with the rapidly increasing speed-maneuvering characteristics of vehicles.

Restricting the distribution of visual attention reduces cybersickness

This study investigated whether increased attention to the central or peripheral visual field can reduce motion sickness in virtual reality (VR). A recent study found that increased attention to the periphery during vection was correlated with lower self-reported motion sickness susceptibility, which suggests that peripheral attention might be beneficial for avoiding cybersickness. We tested this experimentally by manipulating visual attention to central vs. peripheral fields during VR exposure. We also measured attention to the periphery during vection and motion sickness susceptibility to attempt to replicate the previous results. In Experiment 1, task-relevant cues to target locations were provided in the central or peripheral field during navigation in VR, and we found no differences in motion sickness. In Experiment 2, attention to the center or periphery was manipulated with a dot-probe task during passive VR exposure, and we found that motion sickness was greater in the condition that required attention to the periphery. In both experiments, there was no correlation between baseline attentional allocation and self-reported motion sickness susceptibility. Our results demonstrate that restricting attention to the central visual field can decrease cybersickness, which is consistent with previous findings that cybersickness is greater with large FOV.

The Visually Induced Motion Sickness Susceptibility Questionnaire (VIMSSQ): Estimating Individual Susceptibility to Motion Sickness-Like Symptoms When Using Visual Devices

OBJECTIVE

Two studies were conducted to develop and validate a questionnaire to estimate individual susceptibility to visually induced motion sickness (VIMS).

BACKGROUND

VIMS is a common side-effect when watching dynamic visual content from various sources, such as virtual reality, movie theaters, or smartphones. A reliable questionnaire predicting individual susceptibility to VIMS is currently missing. The aim was to fill this gap by introducing the Visually Induced Motion Sickness Susceptibility Questionnaire (VIMSSQ).

METHODS

A survey and an experimental study were conducted. Survey: The VIMSSQ investigated the frequency of nausea, headache, dizziness, fatigue, and eyestrain when using different visual devices. Data were collected from a survey of 322 participants for the VIMSSQ and other related phenomena such as migraine. Experimental study: 23 participants were exposed to a VIMS-inducing visual stimulus. Participants filled out the VIMSSQ together with other questionnaires and rated their level of VIMS using the Simulator Sickness Questionnaire (SSQ).

RESULTS

Survey: The most prominent symptom when using visual devices was eyestrain, and females reported more VIMS than males. A one-factor solution with good scale reliability was found for the VIMSSQ. Experimental study: Regression analyses suggested that the VIMSSQ can be useful in predicting VIMS (R² = .34) as measured by the SSQ, particularly when combined with questions pertaining to the tendency to avoid visual displays and experience syncope (R² = .59).

CONCLUSION

We generated normative data for the VIMSSQ and demonstrated its validity.

APPLICATION

The VIMSSQ can become a valuable tool to estimate one's susceptibility to VIMS based on self-reports.

Learning from Deep Stereoscopic Attention for Simulator Sickness Prediction

Simulator sickness induced by 360° stereoscopic video contents is a prolonged challenging issue in Virtual Reality (VR) system. Current machine learning models for simulator sickness prediction ignore the underlying interdependencies and correlations across multiple visual features which may lead to simulator sickness. We propose a model for sickness prediction by automatic learning and adaptive integrating multi-level mappings from stereoscopic video features to simulator sickness scores. Firstly, saliency, optical flow and disparity features are extracted from videos to reflect the factors causing simulator sickness, including human attention area, motion velocity and depth information. Then, these features are embedded and fed into a 3-dimensional convolutional neural network (3D CNN) to extract the underlying multi-level knowledge which includes low-level and higher-order visual concepts, and global image descriptor. Finally, an attentional mechanism is exploited to adaptively fuse multi-level information with attentional weights for sickness score estimation. The proposed model is trained by an end-to-end approach and validated over a public dataset. Comparison results with state-of-the-art models and ablation studies demonstrated improved performance in terms of Root Mean Square Error (RMSE) and Pearson Linear Correlation Coefficient.

Enhancing Visual Exploration through Augmented Gaze: High Acceptance of Immersive Virtual Biking by Oldest Olds

The diffusion of virtual reality applications dedicated to aging urges us to appraise its acceptance by target populations, especially the oldest olds. We investigated whether immersive virtual biking, and specifically a visuomotor manipulation aimed at improving visual exploration (augmented gaze), was well accepted by elders living in assisted residences. Twenty participants (mean age 89.8 years, five males) performed three 9 min virtual biking sessions pedalling on a cycle ergometer while wearing a Head-Mounted Display which immersed them inside a 360-degree pre-recorded biking video. In the second and third sessions, the relationship between horizontal head rotation and contingent visual shift was experimentally manipulated (augmented gaze), the visual shift being twice (gain = 2.0) or thrice (gain = 3.0) the amount of head rotation. User experience, motion sickness and visual exploration were measured. We found (i) very high user experience ratings, regardless of the gain; (ii) no effect of gain on motion sickness; and (iii) increased visual exploration (slope = +46%) and decreased head rotation (slope = -18%) with augmented gaze. The improvement in visual exploration capacity, coupled with the lack of intolerance signs, suggests that augmented gaze can be a valuable tool to improve the "visual usability" of certain virtual reality applications for elders, including the oldest olds.

The Impact of Physical Motion Cues on Driver Braking Performance: A Clinical Study Using Driving Simulator and Eye Tracker

Driving simulators are increasingly being incorporated by driving schools into a training process for a variety of vehicles. The motion platform is a major component integrated into simulators to enhance the sense of presence and fidelity of the driving simulator. However, less effort has been devoted to assessing the motion cues feedback on trainee performance in simulators. To address this gap, we thoroughly study the impact of motion cues on braking at a target point as an elementary behavior that reflects the overall driver's performance. In this paper, we use an eye-tracking device to evaluate driver behavior in addition to evaluating data from a driving simulator and considering participants' feedback. Furthermore, we compare the effect of different motion levels ("No motion", "Mild motion", and "Full motion") in two road scenarios: with and without the pre-braking warning signs with the speed feedback given by the speedometer. The results showed that a full level of motion cues had a positive effect on braking smoothness and gaze fixation on the track. In particular, the presence of full motion cues helped the participants to gradually decelerate from 5 to 0 ms^-1 in the last 240 m before the stop line in both scenarios, without and with warning signs, compared to the hardest braking from 25 to 0 ms^-1 produced under the no motion cues conditions. Moreover, the results showed that a combination of the mild motion conditions and warning signs led to an underestimation of the actual speed and a greater fixation of the gaze on the speedometer. Questionnaire data revealed that 95% of the participants did not suffer from motion sickness symptoms, yet participants' preferences did not indicate that they were aware of the impact of simulator conditions on their driving behavior.

Design and Implementation of a New Training Flight Simulator System

Aircraft flight simulators have good cost efficiency, high reusability, and high flight safety. All airlines and aircraft manufacturing companies choose it as sophisticated training equipment for ground simulation, effectively reducing pilot training costs, ensuring personnel safety and aircraft wear and tear. The new simulator proposed in this paper combines a digital motion-cueing algorithm, flight software and motion platform to make pilots feel as if they are in the real world. By using EtherCAT technology to drive the motion-cueing platform, it can improve the data transmission speed of the simulator as well as the strong anti-interference ability of communication and the control operation efficiency. Therefore, the simulated flight subjects can perform long-distance and large-angle training. Next, a set of measurement systems was established to provide monitoring items including attitude, velocity and acceleration, which can be displayed on the screen and recorded on the computer in real time and dynamically. Finally, seven training subjects were implemented to demonstrate the feasibility and correctness of the proposed method.

Mitigating motion sickness in automated vehicles with vibration cue system

Motion sickness is very common in road transport. To guarantee ride comfort and user experience, there is an urgent need for effective solutions to motion sickness mitigation in semi- and fully-automated vehicles. Considering both effectiveness and user-friendliness, a vibration cue system is proposed to inform passengers of the upcoming vehicle movement through tactile stimulation. By integrating the motion planning results from automated driving algorithms, the vibration cueing timing and patterns are optimised with the theory of motion anticipation. Using a cushion-based prototype of a vibration cue system, 20 participants were invited to evaluate this solution in two conditions of driving simulator experiments. Results show that the proposed vibration cue system could also help participants to comprehend the cues and to generate motion anticipation. The participants' motion sickness degrees were significantly lowered. This research may serve as one foundation for detailed system development in practical applications. Practitioner Summary: In automated vehicles, passengers engaging in non-driving tasks are apt to severe motion sickness. A vibration cue system and cueing strategy are proposed and optimised to inform passengers of the upcoming vehicle movement. Simulator experiments of 20 participants proved its effectiveness in promoting motion anticipation and reducing motion sickness.

Seasickness among Icelandic seamen

Introduction

The working environment abroad a ship is unique, with constant stimuli such as rolling of the vessel, noise, and vibration. Fishing industry is important for Icelandic economy, still the effect of seasickness-related symptoms on seamen´s health is not fully understood. Thus, the objective of this study is to explore the impact of seasickness-related symptoms, i.e., seasickness, seasickness symptoms and mal de débarquement on seaman´s health, and how their working environment may affect those factors.

Methods

Cross-sectional data was collected from 262 seamen answering questionnaire. Majority of the seamen participated while attending a compulsory course held by the Maritime Safety and Survival Training Centre. The majority of participants were men. A chi-square test was used to detect the difference between variables.

Results

The majority of seamen had experienced seasickness (87.8%) or mal de débarquement (85.8%). Having a history of tension headache (38.1%) and tinnitus (37.9%) was quite common. A total of 30.6% of the participants had been admitted to hospital once or more due to mishaps or accidents on land.

Discussion

Seasickness and seasickness symptoms together with mal de débarquement are common in Icelandic seamen. Working conditions at sea are demanding and seam to affect the seamen´s health both at sea and ashore, making further research needed.

Effect of Visually Induced Motion Sickness from Head-Mounted Display on Cardiac Activity

Head-mounted display (HMD) virtual reality devices can facilitate positive experiences such as co-presence and deep immersion; however, motion sickness (MS) due to these experiences hinders the development of the VR industry. This paper proposes a method for assessing MS caused by watching VR content on an HMD using cardiac features. Twenty-eight undergraduate volunteers participated in the experiment by watching VR content on a 2D screen and HMD for 12 min each, and their electrocardiogram signals were measured. Cardiac features were statistically analyzed using analysis of covariance (ANCOVA). The proposed model for classifying MS was implemented in various classifiers using significant cardiac features. The results of ANCOVA reveal a significant difference between 2D and VR viewing conditions, and the correlation coefficients between the subjective ratings and cardiac features have significant results in the range of -0.377 to -0.711 (for SDNN, pNN50, and ln HF) and 0.653 to 0.677 (for ln VLF and ln VLF/ln HF ratio). Among the MS classification models, the linear support vector machine achieves the highest average accuracy of 91.1% (10-fold cross validation) and has a significant permutation test outcome. The proposed method can contribute to quantifying MS and establishing viewer-friendly VR by determining its qualities.

[The feasibility study of objective evaluation of the severity of motion sickness by quantitative analysis of the facial skin color]

Objective: To explore the feasibility of applying quantitative analysis of the facial skin color to evaluate the severity of motion sickness objectively and to seek objective indicators that can reflect the severity of motion sickness. Methods: Motion sickness was induced in 51 male adult subjects recruited at the Air Force Medical University by Coriolis acceleration stimulation, and facial skin colorimetric values were acquired using a portable spectrophotometer at five time points: before stimulation and at 0 min, 10 min, 20 min and 30 min after the end of stimulation. The Graybiel rating scales were applied to assess the severity of motion sickness in subjects at each time point after stimulation, and the correlation between the magnitude of change in each colorimetric value and the maximum Graybiel's score was analyzed. The ROC curves were used to compare the evaluation performance of colorimetric value indicators which could reflect the severity of motion sickness. Results: Each colorimetric value in the CIE-L^*a^*b^* color system changed significantly after exposure to provocative motion stimuli, and the trend was consistent with the typical sign of pallor in motion sickness. The magnitudes of the increase in the colorimetric value CIE-L^*, the decrease in CIE-a^*, and the increase in CIE-b^* were all significantly and positively correlated with the maximum of Graybiel's scores (r=0.490 0, P=0.000 3; r=0.549 3, P<0.000 1; r=0.540 9, P<0.000 1). Comparing the performance of three colorimetric indicators to assess the severity of motion sickness, CIE-a^* had an area under the ROC curve of 0.875 0, a sensitivity of 85.71%, and a specificity of 87.50%, which was better than CIE-L^* and CIE-b^*. Conclusions: The CIE-L^*a^*b^* colorimeter values can be considered as objective indicators of the severity of motion sickness, among which the colorimetric indicator CIE-a^* has the most diagnostic significance, and the method of quantitative analysis of the facial skin color can provide a new reference for the objective evaluation of the severity of motion sickness.

A Case Study on Vestibular Sensations in Driving Simulators

Motion platforms have been used in simulators of all types for several decades. Since it is impossible to reproduce the accelerations of a vehicle without limitations through a physically limited system (platform), it is common to use washout filters and motion cueing algorithms (MCA) to select which accelerations are reproduced and which are not. Despite the time that has passed since their development, most of these algorithms still use the classical washout algorithm. In the use of these MCAs, there is always information that is lost and, if that information is important for the purpose of the simulator (the training simulators), the result obtained by the users of that simulator will not be satisfactory. This paper shows a case study where a BMW 325Xi AUT fitted with a sensor, recorded the accelerations produced in all degrees of freedom (DOF) during several runs, and data have been introduced in mathematical simulation software (washout + kinematics + actuator simulation) of a 6DOF motion platform. The input to the system has been qualitatively compared with the output, observing that most of the simulation adequately reflects the input to the system. Still, there are three events where the accelerations are lost. These events are considered by experts to be of vital importance for the outcome of a learning process in the simulator to be adequate.

Multi-Criteria Evaluation for Sorting Motion Planner Alternatives

Automated vehicles are expected to push towards the evolution of the mobility environment in the near future by increasing vehicle stability and decreasing commute time and vehicle fuel consumption. One of the main limitations they face is motion sickness (MS), which can put their wide impact at risk, as well as their acceptance by the public. In this direction, this paper presents the application of motion planning in order to minimise motion sickness in automated vehicles. Thus, an optimal control problem is formulated through which we seek the optimum velocity profile for a predefined road path for multiple fixed journey time (JT) solutions. In this way, a Pareto Front will be generated for the conflicting objectives of MS and JT. Despite the importance of optimising both of these, the optimum velocity profile should be selected after taking into consideration additional objectives. Therefore, as the optimal control is focused on the MS minimisation, a sorting algorithm is applied to seek the optimum solution among the pareto alternatives of the fixed time solutions. The aim is that this solution will correspond to the best velocity profile that also ensures the optimum compromise between motion comfort, safety and driving behaviour, energy efficiency, journey time and riding confidence.

EEG-based evaluation of motion sickness and reducing sensory conflict in a simulated autonomous driving environment

Autonomous driving offers significant potential for changes in the automotive industry. However, sensory conflict during autonomous driving can lead to motion sickness. Quantitative evaluation and effective preventions to predict and reduce motion sickness are needed. The goal of this study is to verify the objective indicator of motion sickness level based on encephalography (EEG) that we proposed before and investigate the influence of attenuating sensory conflict on motion sickness. A 6-degree of freedom (DOF) driving simulator platform was used to provide an autonomous driving environment to the subjects, and the subjective motion sickness level (MSL), as well as the EEG signals of 15 healthy subjects, were collected simultaneously during 3 conditions, i) autonomous driving, ii) autonomous driving with eyes blindfolded and iii) active driving. The MSLs were reported by the subjects every two minutes, providing a reference to the recorded EEG signals. The EEG signals were analyzed and compared among different conditions. Average MSLs were higher in autonomous driving than in autonomous driving with eyes blindfolded and active driving, together with the increase of the mean EEG frequency of theta band in the central, parietal and occipital areas (FC5, Cz, CP5, P3, and POz). These findings validated that EEG mean frequency of theta band could be an indicator of motion sickness, besides an attenuated visual input or active control of the vehicle can effectively reduce the generation of motion sickness.

Visual Vestibular Conflict Mitigation in Virtual Reality Using Galvanic Vestibular Stimulation

BACKGROUND: Virtual reality (VR) is an effective technique to reduce cost and increase fidelity in training programs. In VR, visual and vestibular cues are often in conflict, which may result in simulator-induced motion sickness. The purpose of this study is to investigate the integration of Galvanic Vestibular Stimulation (GVS) with a VR flight training simulator by assessing flight performance, secondary task performance, simulator sickness and presence.METHODS: There were 20 participants who performed 2 separate VR flight simulation sessions, with and without GVS (control). Flight performance, secondary task performance, and electrogastrogram were measured during VR flight simulation. The standardized simulator sickness and presence questionnaires were administered.RESULTS: Electrogastrogram measures such as dominant power instability coefficient (DPIC) and percentages of bradygastric waves (%B) were lower in the GVS session than the control session in the flight simulation (DPIC: 0.44 vs. 0.54; %B: 21.2% vs. 30.5%) and postflight (DPIC: 0.38 vs. 0.53; %B: 22.8% vs. 31.4%) periods. Flight performance (#hit-gates) was improved in the GVS session compared to the control (GVS: 17, Control: 15.5). Secondary task performance (%hits) was improved with GVS for the Easy task (GVS: 55.5%, Control: 43.1%).DISCUSSION: This study demonstrates the potential of synchronizing GVS with visual stimuli in VR flight training to reduce visual-vestibular sensory conflict to improve fidelity and performance. These results provide initial evidence, but continued research is warranted to further understand the benefits and applications of GVS in VR simulator training.Pradhan GN, Galvan-Garza RC, Perez AM, Stepanek J, Cevette MJ. Visual vestibular conflict mitigation in virtual reality using galvanic vestibular stimulation. Aerosp Med Hum Perform. 2022; 93(5):406-414.

Studying the Effects of Congruence of Auditory and Visual Stimuli on Virtual Reality Experiences

Studies in virtual reality (VR) have introduced numerous multisensory simulation techniques for more immersive VR experiences. However, although they primarily focus on expanding sensory types or increasing individual sensory quality, they lack consensus in designing appropriate interactions between different sensory stimuli. This paper explores how the congruence between auditory and visual (AV) stimuli, which are the sensory stimuli typically provided by VR devices, affects the cognition and experience of VR users as a critical interaction factor in promoting multisensory integration. We defined the types of (in)congruence between AV stimuli, and then designed 12 virtual spaces with different types or degrees of congruence between AV stimuli. We then evaluated the presence, immersion, motion sickness, and cognition changes in each space. We observed the following key findings: 1) there is a limit to the degree of temporal or spatial incongruence that can be tolerated, with few negative effects on user experience until that point is exceeded; 2) users are tolerant of semantic incongruence; 3) a simulation that considers synesthetic congruence contributes to the user's sense of immersion and presence. Based on these insights, we identified the essential considerations for designing sensory simulations in VR and proposed future research directions.

The perception threshold of the vestibular Coriolis illusion

BACKGROUND

The vestibular Coriolis illusion is a disorienting sensation that results from a transient head rotation about one axis during sustained body rotation about another axis. Although often used in spatial disorientation training for pilots and laboratory studies on motion sickness, little is known about the minimum required rotation rate to produce the illusion.

OBJECTIVE

This study determined the perception threshold associated with the Coriolis illusion.

METHODS

Nineteen participants performed a standardized pitching head movement during continuous whole-body yaw rotation at rates varying between 5 to 50 deg/s. The participants reported their motion sensation in relation to three hypothesized perception thresholds: 1) any sense of motion, 2) a sense of rotation, and 3) a sense of rotation and its direction (i.e., the factual Coriolis illusion). The corresponding thresholds were estimated from curves fitted by a generalized linear model.

RESULTS

On average threshold 1 was significantly lower (8 deg/s) than thresholds 2 and 3. The latter thresholds did not differ from each other and their pooled value was 10 deg/s.

CONCLUSIONS

The Coriolis illusion is perceived at yaw rates exceeding 10 deg/s using a pitching head movement with 40 deg amplitude and 55 deg/s peak velocity. Model analysis shows that this corresponds to an internal rotation vector of 6 deg/s. With this vector the Coriolis perception threshold can be predicted for any other head movement.

A comparison of cybersickness symptoms across 360-degree hazard perception and hazard prediction tests for drivers

Hazard perception assessment may benefit from VR-presentation by removing field-of-view restrictions imposed by single-screen tests. One concern is whether VR-induced 'cybersickness' will offset any benefits. Self-reported cybersickness ratings were recorded from 77 participants viewing two variants of a 360-degree hazard test: hazard perception and hazard prediction. The latter was hypothesised to be particularly susceptible as clips abruptly cut to a probe question at hazard onset. Such sudden occlusions are thought to increase cybersickness. Overall cybersickness levels were low, with only four participants excluded for above-threshold sickness ratings. The remaining participants showed unexpectedly lower symptoms for the hazard prediction test and rated this test format as more comfortable and engaging. These findings mitigate concerns over the use of 360-degree videos in formative hazard assessments, even when clips involve sudden occlusions. Nonetheless, removal of any participants due to cybersickness raises problems for using VR for formal assessments of hazard perception skill.

A comparative study of navigation interfaces in virtual reality environments: A mixed-method approach

Recently, motion-based navigation interfaces have been widely utilized in virtual reality (VR) environments. However, improper navigation interfaces can negatively impact the VR experience, and because different interfaces have different characteristics, the navigation experience may vary. Although comparative studies have been conducted with various interfaces, information obtained by focusing on qualitative evaluation was limited. Thus, this study explores the effects from three navigation interfaces (walking-in-place (WIP), joystick, and teleportation) on user performance, sense of presence, workload, usability, and motion sickness through a mixed-method design. Twenty-one participants were asked to perform a navigation task using selected navigation interfaces. The results indicated different advantages and disadvantages in the navigation interfaces for each evaluation metric. In particular, it was found that more research on user safety is required for the WIP interface. The findings of this study are expected to contribute to the development of guidelines for applying navigation interfaces to specific VR environments.

Improvement of three-dimensional motion sickness using a virtual reality simulator for robot-assisted surgery in undergraduate medical students: A prospective observational study

BACKGROUND

A virtual reality (VR) simulator is utilized as an inexpensive tool for gaining basic technical competence in robotic-assisted surgery (RAS). We evaluated operator 3D motion sickness while using a VR simulator and assessed whether it can be reduced by repeating the training.

METHODS

This prospective observational study was conducted at the Department of Urology, Iwate Medical University, a tertiary training hospital in an urban setting. A total of 30 undergraduate medical students participated in the study. We compared whether the VR simulator improved the students' skills in operating the da Vinci robot. Fifteen students underwent training with a VR simulator for 4 h a day for 5 days. Then, motion sickness was determined using the Visual Analog Scale and Simulator Sickness Questionnaire (SSQ) before and after the training.

RESULTS

Manipulation time significantly improved after training compared to before training (293.9 ± 72.4 versus 143.6 ± 18.4 s; p < 0.001). Although motion sickness worsened after each training session, it gradually improved with continuous practice with the VR simulator. SSQ subscores showed that the VR simulator induced nausea, disorientation, and oculomotor strain, and oculomotor strain was significantly improved with repeated training.

CONCLUSIONS

In undergraduate students, practice with the VR simulator improved RAS skills and operator 3D motion sickness caused by 3D manipulation of the da Vinci robot.

Motion sickness and sense of presence in a virtual reality environment developed for manual wheelchair users, with three different approaches

Visually Induced Motion Sickness (VIMS) is a bothersome and sometimes unsafe experience, frequently experienced in Virtual Reality (VR) environments. In this study, the effect of up to four training sessions to decrease VIMS in the VR environment to a minimal level was tested and verified through explicit declarations of all 14 healthy participants that were recruited in this study. Additionally, the Motion Sickness Assessment Questionnaire (MSAQ) was used at the end of each training session to measure responses to different aspects of VIMS. Total, gastrointestinal, and central motion sickness were shown to decrease significantly by the last training session, compared to the first one. After acclimatizing to motion sickness, participants' sense of presence and the level of their motion sickness in the VR environment were assessed while actuating three novel and sophisticated VR systems. They performed up to four trials of the Illinois agility test in the VR systems and the real world, then completed MSAQ and Igroup Presence Questionnaire (IPQ) at the end of each session. Following acclimatization, the three VR systems generated relatively little motion sickness and high virtual presence scores, with no statistically meaningful difference among them for either MSAQ or IPQ. Also, it was shown that presence has a significant negative correlation with VIMS.

Individual differences in the temporal progression of motion sickness and anxiety: the role of passengers' trait anxiety and motion sickness history

The objective of the study is to show that trait anxiety and motion sickness history are responsible for different temporal progressions of sickness in passengers. The level of inflight anxiety and inflight sickness severity was monitored for 124 passengers in a full-motion cabin simulator during a short-haul flight with four different flight segments. Four groups with different characteristics in trait anxiety and motion sickness susceptibility showed different profiles of inflight sickness development. High trait anxiety was responsible for high inflight anxiety and a constantly high level of motion sickness, while passengers with just a motion sickness history showed an increase in motion sickness severity over time. We suggest that trait anxiety and motion sickness susceptibility interact and have an impact on the temporal progression of inflight sickness severity. The analysis of temporal developments of anxiety and sickness are fruitful for understanding the origins of motion sickness, research and individual treatments. Practitioner summary: In a full-motion cabin simulator study with 124 passengers the level of inflight anxiety and inflight sickness severity was monitored. Trait anxiety and motion sickness history were found to have different impacts on the temporal progression of individual sickness severity. Abbreviations: ANOVA: analysis of variance; AVES: air vehicle simulator; hiA/hiM: group with high anxiety and high motion sickness susceptibility; hiA/loM: group with high anxiety and low motion sickness susceptibility;MSSQ: motion sickness susceptibility scale; loA/hiM: group with low anxiety and high motion sickness susceptibility; loA/loM: group with low anxiety and low motion sickness susceptibility; SPSS: statistical package for the social sciences; SSQ-TS: total score from the simulator sickness questionaire; STAI: state trait anxiety inventory.

Comparing the Differences in Brain Activities and Neural Comodulations Associated With Motion Sickness Between Drivers and Passengers

It is common to believe that passengers are more adversely affected by motion sickness than drivers. However, no study has compared passengers and drivers' neural activities and drivers experiencing motion sickness (MS). Therefore, this study attempts to explore brain dynamics in motion sickness among passengers and drivers. Eighteen volunteers participated in simulating the driving winding road experiment while their subjective motion sickness levels and electroencephalogram (EEG) signals were simultaneously recorded. Independent Component Analysis (ICA) was employed to isolate MS-related independent components (ICs) from EEG. Furthermore, comodulation analysis was applied to decompose spectra of interest ICs, related to MS, to find the specific spectra-related temporally independent modulators (IMs). The results showed that passengers' alpha band (8-12 Hz) power increased in correlation with the MS level in the parietal, occipital midline and left and right motor areas, and drivers' alpha band (8-12 Hz) power showed relatively smaller increases than those in the passenger. Further, the results also indicate that the enhanced activation of alpha IMs in the passenger than the driver is due to a higher degree of motion sickness. In conclusion, compared to the driver, the passenger experience more conflicts among multimodal sensory systems and demand neuro-physiological regulation.

Non-Contact Measurement of Motion Sickness Using Pupillary Rhythms from an Infrared Camera

Both physiological and neurological mechanisms are reflected in pupillary rhythms via neural pathways between the brain and pupil nerves. This study aims to interpret the phenomenon of motion sickness such as fatigue, anxiety, nausea and disorientation using these mechanisms and to develop an advanced non-contact measurement method from an infrared webcam. Twenty-four volunteers (12 females) experienced virtual reality content through both two-dimensional and head-mounted device interpretations. An irregular pattern of the pupillary rhythms, demonstrated by an increasing mean and standard deviation of pupil diameter and decreasing pupillary rhythm coherence ratio, was revealed after the participants experienced motion sickness. The motion sickness was induced while watching the head-mounted device as compared to the two-dimensional virtual reality, with the motion sickness strongly related to the visual information processing load. In addition, the proposed method was verified using a new experimental dataset for 23 participants (11 females), with a classification performance of 89.6% (n = 48) and 80.4% (n = 46) for training and test sets using a support vector machine with a radial basis function kernel, respectively. The proposed method was proven to be capable of quantitatively measuring and monitoring motion sickness in real-time in a simple, economical and contactless manner using an infrared camera.

Mitigating Cybersickness in Virtual Reality Systems through Foveated Depth-of-Field Blur

Cybersickness is one of the major roadblocks in the widespread adoption of mixed reality devices. Prolonged exposure to these devices, especially virtual reality devices, can cause users to feel discomfort and nausea, spoiling the immersive experience. Incorporating spatial blur in stereoscopic 3D stimuli has shown to reduce cybersickness. In this paper, we develop a technique to incorporate spatial blur in VR systems inspired by the human physiological system. The technique makes use of concepts from foveated imaging and depth-of-field. The developed technique can be applied to any eye tracker equipped VR system as a post-processing step to provide an artifact-free scene. We verify the usefulness of the proposed system by conducting a user study on cybersickness evaluation. We used a custom-built rollercoaster VR environment developed in Unity and an HTC Vive Pro Eye headset to interact with the user. A Simulator Sickness Questionnaire was used to measure the induced sickness while gaze and heart rate data were recorded for quantitative analysis. The experimental analysis highlighted the aptness of our foveated depth-of-field effect in reducing cybersickness in virtual environments by reducing the sickness scores by approximately 66%.

Profiling of cybersickness and balance disturbance induced by virtual ship motion immersion combined with galvanic vestibular stimulation

Profile of cybersickness and balance disturbance induced by virtual ship motion alone and in combination with galvanic vestibular stimulation (GVS) remained unclear. Subjects were exposed to a ship deck vision scene under simulated Degree 5 or 3 sea condition using a head-mounted virtual reality display with or without GVS. Virtual ship motion at Degree 5 induced significant cybersickness with symptom profile: nausea syndrome > central (headache and dizziness) > peripheral (cold sweating) > increased salivation. During a single session of virtual ship motion exposure, GVS aggravated balance disturbance but did not affect most cybersickness symptoms except cold sweating. Repeated exposure induced cybersickness habituation which was delayed by GVS, while the temporal change of balance disturbance was unaffected. These results suggested that vestibular inputs play different roles in cybersickness and balance disturbance during virtual reality exposure. GVS might not serve as a potential countermeasure against cybersickness induced by virtual ship motion.

Assessing Postural Instability and Cybersickness Through Linear and Angular Displacement

OBJECTIVE

To examine the hypothesis that constant speed is more comfortable than variable speed profiles and may minimize cybersickness.

BACKGROUND

Current best practices for virtual reality (VR) content creation suggest keeping any form of acceleration as short and infrequent as possible to mitigate cybersickness.

METHODS

In Experiment 1, participants experienced repetitions of simulated linear motion, and in Experiment 2, they experienced repetitions of a circular motion. Three speed profiles were tested in each experiment. Each trial lasted 2 min while standing. Cybersickness was measured using the Simulator Sickness Questionnaire (SSQ) and operationally defined in terms of total severity scores. Postural stability was measured using a Wii Balance Board and operationally defined in terms of center of pressure (COP) path length. Postural measures were decomposed into anterior-posterior and medial-lateral axes and subjected to detrended fluctuation analysis.

RESULTS

For both experiments, no significant differences were observed between the three speed profiles in terms of cybersickness or postural stability, and none of the baseline postural measures could predict SSQ scores for the speed profile conditions. An axis effect was observed in both experiments such that normalized COP movement was significantly greater along the anterior-posterior axis than the medial-lateral axis.

CONCLUSION

Results showed no convincing evidence to support the common belief that constant speed is more comfortable than variable speed profiles for scenarios typical of VR applications.

APPLICATION

The present findings offer guidelines for the design of locomotion techniques involving traversal in VR environments.

Postural precursors of motion sickness in head-mounted displays: drivers and passengers, women and men

Motion sickness is preceded by distinctive patterns of postural activity that differ between the sexes. We asked whether such postural precursors of motion sickness might exist before participants were exposed to a virtual driving game presented via a head-mounted display. Men and women either controlled a virtual vehicle (drivers), or viewed a recording of virtual vehicle motion (passengers). Before exposure to the game, we recorded standing body sway while participants performed simple visual tasks (staring at a blank page vs. counting target letters in a block of text). Following game exposure, participants were classified into Well and Sick groups. In a statistically significant interaction, the multifractality of body sway varied as a function of sex, vehicle control, and motion sickness status. The results confirm that postural precursors of motion sickness differ between the sexes, and extend these to the control of virtual vehicles in head-mounted displays. Practitioner Summary: We asked whether postural sway might predict motion sickness during exposure to a driving game via a head-mounted display. Participants drove a virtual car (drivers), or watched recorded car motion (passengers). Beforehand, we measured standing body sway. Postural precursors of motion sickness differed between the sexes and drivers and passengers. Abbreviations: M: meters; SD: standard deviation; kg: kilograms; COP: centre of pressure; AP: anterior-posterior; ML: mediolateral; cm: centimeters; s: seconds; min: minutes; MF: DFA: multifractal detrended fluctuation analysis; DFA: detrended fluctuation analysis; ANOVA: analysis of variance; CI: confidence interval; Hz: hertz; SE: standard error of the mean.

Knowing What's Coming: Unpredictable Motion Causes More Motion Sickness

OBJECTIVE

This study explores the role of anticipation in motion sickness. We compared three conditions varying in motion predictability and assessed the effect of anticipation on subsequent illness ratings using a within-subjects design.

BACKGROUND

Anticipation is thought to play a role in motion sickness by reducing the discrepancy between sensed and expected sensory information. However, both the exact role and potential magnitude of anticipation on motion sickness are unknown.

METHOD

Participants (N = 17) were exposed to three 15-min conditions consisting of repeated fore-aft motion on a sled on a 40-m rail (1) at constant intervals and consistent motion direction, (2) at constant intervals but varied motion direction, and (3) at varied intervals but consistent motion direction. Conditions were otherwise identical in motion intensity and displacement, as they were composed of the same repetitions of identical blocks of motion. Illness ratings were recorded at 1-min intervals using an 11-point motion sickness scale.

RESULTS

Average illness ratings after exposure were significantly lower for the predictable condition, compared with both the directionally unpredictable condition and the temporally unpredictable condition.

CONCLUSION

Unpredictable motion is significantly more provocative compared with predictable motion. Findings suggest motion sickness results from a discrepancy between sensed and expected motion, rather than from unpreparedness to motion.

APPLICATION

This study underlines the importance of an individual's anticipation to motion in motion sickness. Furthermore, this knowledge could be used in domains such as that of autonomous vehicles to reduce carsickness.

Impact of Different Sensory Stimuli on Presence in Credible Virtual Environments

Multiple factors can affect presence in virtual environments, such as the number of human senses engaged in a given experience or the extent to which the virtual experience is credible. The purpose of the present work is to study how the inclusion of credible multisensory stimuli affects the sense of presence, namely, through the use of wind, passive haptics, vibration, and scent. Our sample consisted of 37 participants (27 men and 10 women) whose ages ranged from 17 to 44 years old and were mostly students. The participants were divided randomly into 3 groups: Control Scenario (visual and auditory - N = 12), Passive Haptic Scenario (visual, auditory, and passive haptic - N = 13) and Multisensory Scenario (visual, auditory, wind, passive haptic, vibration, and scent - N = 12). The results indicated a significant increase in the involvement subscale when all multisensory stimuli were delivered. We found a trend where the use of passive haptics by itself has a positive impact on presence, which should be the subject of further work.

Tolerability of daily intermittent or continuous short-arm centrifugation during 60-day 6o head down bed rest (AGBRESA study)

Artificial gravity through short-arm centrifugation has potential as a multi-system countermeasure for deconditioning and cranial fluid shifts that may underlie ocular issues in microgravity. However, the optimal short-arm centrifugation protocol that is effective whilst remaining tolerable has yet to be determined. Given that exposure to centrifugation is associated with presyncope and syncope and in addition motion sickness an intermittent protocol has been suggested to be more tolerable. Therefore, we assessed cardiovascular loading and subjective tolerability of daily short arm centrifugation with either an intermittent or a continuous protocol during long-term head-down bed rest as model for microgravity exposure in a mixed sex cohort. During the Artificial Gravity Bed Rest with European Space Agency (AGBRESA) 60 day 6° head down tilt bed rest study we compared the tolerability of daily +1 Gz exposure at the center of mass centrifugation, either performed continuously for 30 minutes, or intermittedly (6 x 5 minutes). Heart rate and blood pressure were assessed daily during centrifugation along with post motion sickness scoring and rate of perceived exertion. During bed rest, 16 subjects (6 women, 10 men), underwent 960 centrifuge runs in total. Ten centrifuge runs had to be terminated prematurely, 8 continuous runs and 2 intermittent runs, mostly due to pre-syncopal symptoms and not motion sickness. All subjects were, however, able to resume centrifuge training on subsequent days. We conclude that both continuous and intermittent short-arm centrifugation protocols providing artificial gravity equivalent to +1 Gz at the center of mass is tolerable in terms of cardiovascular loading and motion sickness during long-term head down tilt bed rest. However, intermittent centrifugation appears marginally better tolerated, albeit differences appear minor.

Postural Instability and Seasickness in a Motion-Based Shooting Simulation

BACKGROUND: Motion sickness is a problem for many; however, it is especially pressing for military personnel who need to operate in life and death environments. The current study investigated the underlying cause of motion sickness by testing postural instability theory.METHODS: Subjects experienced realistic motion profiles while performing a virtual reality shooting task and reporting any motion sickness symptoms. Postural instability was manipulated within 20 subjects across 2 conditions. In one condition, subjects could readily adapt their posture to the motion profile by adjusting their feet on the platform (Free), and in the other condition, their feet were fixed in place on the moving platform (Fixed). This Free condition decreased postural instability by allowing adjustment, while the Fixed condition increased postural instability by restricting adjustment. The same subjects completed both conditions to control for individual differences in motion sickness susceptibility.RESULTS: Overall, motion sickness was mild as measured by SSQ (M 14.41, Free; M 18.89, Fixed), and no statistically significant differences were observed between the conditions. Performance on the shooting task was reduced in accuracy by approximately 40%, although this result did not differ between conditions.DISCUSSION: The results do not support postural instability as a contributing factor in motion sickness symptomology. They also demonstrate the importance of accounting for motion when conducting training.Pettijohn KA, Pistone DV, Warner AL, Roush GJ, Biggs AT. Postural instability and seasickness in a motion-based shooting simulation. Aerosp Med Hum Perform. 2020; 91(9):703709.