Allocating less attention to central vision during vection is correlated with less motion sickness

Association between anxiety and skin conductance according to the intensity of shaking of virtual reality images

Introduction

Despite the advantages of virtual reality (VR), cyber sickness makes it difficult to apply VR to those who are already anxious and in distress. Skin conductance (SC) is widely used as a bio-signal reflecting anxiety. It is positively correlated with anxiety. The objective of this study was to determine the association between SC and anxiety in VR.

Methods

Healthy volunteers with moderate-to-high stress defined as a Perceived Stress Scale-10 (PSS-10) score ≥20 were enrolled. STAI-X-1 was used to measure anxiety, and galvanic skin response was used to measure SC. This study used an open, randomized, crossover design. In this study, 360° videos consisted of two types, namely, less dizzying video (G1) and more dizzying video (G2). We randomized subjects into two groups according to video exposure order: G1 after watching G2 (Order 1) and G2 after watching G1 (Order 2). Of 81 subjects, the average age (±SD) was 39.98 ± 10.94 years for the Order 1 group and 36.54 ± 12.44 years for the Order 2 group.

Results

Anxiety was significantly decreased in the Order 2 group (p < 0.035) after watching videos, whereas there was no significant change in anxiety in the Order 1 group. In both groups, SC was significantly increased after exposure to a dizzying video. Mean difference (SD) between the second VR video and baseline SC was 1.61 (1.07) (p < 0.0001) in the Order 1 group and 0.92 (0.90) (p < 0.0001) in the Order 2 group, showing a significant difference between the two groups (p < 0.003). However, there was no significant difference between the two groups (p < 0.077) after baseline correction.

Conclusion

Anxiety was decreased significantly in the Order 2 group. The Order 1 group showed a high rate of change in skin conductivity. It is possible to reduce SC and anxiety by viewing a less dizzying VR video first and then viewing a more dizzying video later.

Vection induced by a pair of patches of synchronized visual motion stimuli covering total field of views as small as 10 square-degrees

Vection (illusion of self-motion) is known to be induced by watching large field-of-view (FOV) moving scenes. In our study, we investigated vection induced by small FOV stimuli. Three experiments were conducted in 45 sessions to analyze vection provoked by moving scenes covering total FOVs as small as 10 square-degrees. Results indicated that 88% of the participants reported vection while watching two small patches of moving dots (1° horizontal by 5° vertical, each) placed on the left and right sides of the observers. This is less than a quarter of the total visual area of two Apple Watches viewed at a distance of 40 cm. Occlusion of the visual field between the two display patches significantly increased the levels of rated vection. Similarly, increasing the speed of the moving dots of the two display patches from about 5 to 25 °/sec increased the levels of rated vection significantly. The location of the two patches in the horizontal visual field did not affect the vection perception significantly. When the two straight stripes of dots were moving in opposite directions, participants perceived circular vection. The observers connected the two stimuli in their minds and perceived them as parts of a single occluded background. The findings of this study are relevant to the design of mobile devices (e.g., smartphones) and wearable technology (e.g., smart watches) with small display areas.

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.

Prior Exposure to Dynamic Visual Displays Reduces Vection Onset Latency

While compelling illusions of self-motion (vection) can be induced purely by visual motion, they are rarely experienced immediately. This vection onset latency is thought to represent the time required to resolve sensory conflicts between the stationary observer's visual and nonvisual information about self-motion. In this study, we investigated whether manipulations designed to increase the weightings assigned to vision (compared to the nonvisual senses) might reduce vection onset latency. We presented two different types of visual priming displays directly before our main vection-inducing displays: (1) 'random motion' priming displays - designed to pre-activate general, as opposed to self-motion-specific, visual motion processing systems; and (2) 'dynamic no-motion' priming displays - designed to stimulate vision, but not generate conscious motion perceptions. Prior exposure to both types of priming displays was found to significantly shorten vection onset latencies for the main self-motion display. These experiments show that vection onset latencies can be reduced by pre-activating the visual system with both types of priming display. Importantly, these visual priming displays did not need to be capable of inducing vection or conscious motion perception in order to produce such benefits.

Alertness and Visual Attention Impact Different Aspects of the Optokinetic Reflex

Purpose

Assessing visual attention and alertness is of great importance in visual and cognitive neuroscience, providing objective measures valuable for both researchers and clinicians. This study investigates how the optokinetic response differs between levels of visual attention in healthy adults while controlling for alertness.

Methods

Twelve healthy subjects (8 men and 4 women; mean age = 33 ± 9.36) with intact gaze-stability, visual acuity, and binocularity were recruited. Subjects viewed a rotating visual scene provoking torsional optokinetic nystagmus (OKN) while wearing a video eye tracker in a seated head-fixed position. Tasks requiring focused, neutral, and divided visual attention were issued to each subject and the OKN was recorded. Pupil sizes were monitored as a proxy for alertness.

Results

Pupil dilation was increased for both focused and divided visual attention. The number of nystagmus beats was highest for the focused condition and lowest for the divided attentional task. OKN gain was increased during both focused and divided attention. The distribution of nystagmus beats over time showed that only focused attention produced a reliable adaptation of the OKN.

Conclusions

Results consequently indicate that OKN frequency is adaptive to a viewer's level of visual attention, whereas OKN gain is influenced by alertness levels. This pattern offers insight into the neural processes integrating visual input with reflexive motor responses. For example, it contextualizes why attention to visual stimuli can cause dizziness, as the OKN frequency reflects activity of the velocity storage mechanism. Additionally, the OKN could offer a possible venue for differentiating between visual attention and alertness during psychometric testing.

The Effect of Motion Direction and Eccentricity on Vection, VR Sickness and Head Movements in Virtual Reality

Virtual Reality (VR) experienced through head-mounted displays often leads to vection, discomfort and sway in the user. This study investigated the effect of motion direction and eccentricity on these three phenomena using optic flow patterns displayed using the Valve Index. Visual motion stimuli were presented in the centre, periphery or far periphery and moved either in depth (back and forth) or laterally (left and right). Overall vection was stronger for motion in depth compared to lateral motion. Additionally, eccentricity primarily affected stimuli moving in depth with stronger vection for more peripherally presented motion patterns compared to more central ones. Motion direction affected the various aspects of VR sickness differently and modulated the effect of eccentricity on VR sickness. For stimuli moving in depth far peripheral presentation caused more discomfort, whereas for lateral motion the central stimuli caused more discomfort. Stimuli moving in depth led to more head movements in the anterior-posterior direction when the entire visual field was stimulated. Observers demonstrated more head movements in the anterior-posterior direction compared to the medio-lateral direction throughout the entire experiment independent of motion direction or eccentricity of the presented moving stimulus. Head movements were elicited on the same plane as the moving stimulus only for stimuli moving in depth covering the entire visual field. A correlation showed a positive relationship between dizziness and vection duration and between general discomfort and sway. Identifying where in the visual field motion presented to an individual causes the least amount of VR sickness without losing vection and presence can guide development for Virtual Reality games, training and treatment programmes.

Joint and individual effectiveness of galvanic cutaneous stimulation and tactile stimulation at decreasing Simulator Adaptation Syndrome

This research was focused on investigating the effectiveness of galvanic cutaneous stimulation and tactile stimulation jointly and individually at mitigating Simulator Adaptation Syndrome. Forty drivers (mean age = 23.1 ± 3.4 years old, twenty women) participated in a driving simulation experiment. Total scores of the Simulator Sickness Questionnaire, head movements (an index of body balance), and driving performance variables were compared across four different stimulation conditions: i) baseline (where no stimulation was presented), ii) galvanic cutaneous stimulation and iii) tactile stimulation deployed individually, and iv) both techniques deployed jointly. The results showed that both techniques presented in conjunction alleviate Simulator Adaptation Syndrome and improve driving performance more effectively than when they are presented in isolation. Importantly, reduced head movements were only revealed when galvanic cutaneous stimulation was applied. We concluded that the reduction of this syndrome is due to an improvement of body balance (elicited by galvanic cutaneous stimulation), and a distraction from the symptoms (elicited by tactile stimulation). We encourage the use of both techniques simultaneously to decrease Simulator Adaptation Syndrome.

Decreasing motion sickness by mixing different techniques

We investigated the effectiveness of galvanic cutaneous stimulation (GCS) and auditory stimulation (AS) together and separately in mitigating motion sickness (MS). Forty-eight drivers (twenty-two men; mean age = 21.58 years) participated in a driving simulation experiment. We compared the total scores of the Simulator Sickness Questionnaire (SSQ) across four different stimulation conditions (GCS, AS, Mixed GCS-AS and no stimulation as a baseline condition). We provided evidence that mixing techniques mitigates MS owing to an improvement in body balance; furthermore, mixing techniques improves driving behavior more effectively than GCS and AS in isolation. We encourage the use of the two techniques together to decrease MS.

Effect of economically friendly acustimulation approach against cybersickness in video-watching tasks using consumer virtual reality devices

BACKGROUND

Consumer virtual reality (VR) devices are becoming more prevalent in the market, but cybersickness induced by VR devices limits their potential application and promotion. Acustimulation has been found effective in reducing cybersickness symptoms. However, in previous forms, the more effective way of acustimulation is either intrusive or electrical which is hard to be applied to daily VR use.

PURPOSE

In this study, we aimed to find a both simple and more effective acustimulation approach, acupressure plus acupaste (AcP+) to reducing the adverse effects caused by cybersickness from VR applications.

METHOD

In this study, we set three conditions: acupressure plus acupaste (AcP+) (main condition of interest), acupressure with fake acupaste (AcP), and a no acustimulation condition (NoAcP). In AcP and AcP + conditions, we applied acupressure or acupressure with true acupaste on P6 point before conducting video-watching tasks using VR headsets, while in NoAcP condition, participants received no special treatment before video-watching tasks. We used questionnaires to measure symptoms of cybersickness and compared the results between these 3 conditions, especially between acupressure plus acupaste (AcP+) and acupressure (AcP) to examine the effect of AcP+, and compared AcP and AcP+ with NoAcP to confirm the effect of acustimulation.

RESULT

Participants reported significant fewer symptoms of cybersickness nausea feelings in both acustimulation methods, compared with NoAcP; and AcP+ was more effective than AcP against cybersickness on visual oculomotor aspect, and facilitated cybersickness recovery.

IMPLICATION

It would be promising to develop acupressure equipment and apply stimulation before VR application to reduce cybersickness.

Recent Progress in Space Physiology and Aging

Astronauts coming back from long-term space missions present with different health problems potentially affecting mission performance, involving all functional systems and organs and closely resembling those found in the elderly. This review points out the most recent advances in the literature in areas of expertise in which specific research groups were particularly creative, and as they relate to aging and to possible benefits on Earth for disabled people. The update of new findings and approaches in space research refers especially to neuro-immuno-endocrine-metabolic interactions, optic nerve edema, motion sickness and muscle-tendon-bone interplay and aims at providing the curious - and even possibly naïve young researchers – with a source of inspiration and of creative ideas for translational research.