Vection change exacerbates simulator sickness in virtual environments

The optic flow patterns generated by virtual reality (VR) systems typically produce visually induced experiences of self-motion (vection). While this vection can enhance presence in VR, it is often accompanied by a variant of motion sickness called simulator sickness (SS). However, not all vection experiences are the same. In terms of perceived heading and/or speed, visually simulated self-motion can be either steady or changing. It was hypothesized that changing vection would lead to more SS. Participants viewed an optic flow pattern that either steadily expanded or alternately expanded and contracted. In one experiment, SS was measured pretreatment and after 5 min of viewing using the Simulator Sickness Questionnaire. In a second experiment employing the same stimuli, vection onset and magnitude were measured using a computer-interfaced slide indicator. The steadily expandingflow pattern, compared to the expanding and contracting pattern, led to: 1) significantly less SS, 2) lower subscores for nausea, oculomotor, and disorientation symptoms, 3) more overall vection magnitude, and 4) less changing vection. Collectively, these results suggest that changing vection exacerbate SS

Frequency Characteristics of Visually Induced Motion Sickness

This article was published in the journal, Human Factors [Sage Publications / © Human Factors and Ergonomics Society.]. The definitive version is available at: http://dx.doi.org/10.1177/0018720812469046Objective: The aim of this study was to explore the frequency response of visually induced motion sickness (VIMS) for oscillating linear motion in the foreand- aft axis. Background: Simulators, virtual environments, and commercially available video games that create an illusion of self-motion are often reported to induce the symptoms seen in response to true motion. Often this human response can be the limiting factor in the acceptability and usability of such systems. Whereas motion sickness in physically moving environments is known to peak at an oscillation frequency around 0.2 Hz, it has recently been suggested that VIMS peaks at around 0.06 Hz following the proposal that the summed response of the visual and vestibular selfmotion systems is maximized at this frequency. Methods: We exposed 24 participants to random dot optical flow patterns simulating oscillating foreand- aft motion within the frequency range of 0.025 to 1.6 Hz. Before and after each 20-min exposure, VIMS was assessed with the Simulator Sickness Questionnaire. Also, a standard motion sickness scale was used to rate symptoms at 1-min intervals during each trial. Results: VIMS peaked between 0.2 and 0.4 Hz with a reducing effect at lower and higher frequencies. Conclusion: The numerical prediction of the “crossover frequency” hypothesis, and the design guidance curve previously proposed, cannot be accepted when the symptoms are purely visually induced. Application: In conditions in which stationary observers are exposed to optical flow that simulates oscillating fore-and-aft motion, frequencies around 0.2 to 0.4 Hz should be avoided

Virtual slides in peer reviewed, open access medical publication

<p>Abstract</p> <p>Background</p> <p>Application of virtual slides (VS), the digitalization of complete glass slides, is in its infancy to be implemented in routine diagnostic surgical pathology and to issues that are related to tissue-based diagnosis, such as education and scientific publication.</p> <p>Approach</p> <p>Electronic publication in Pathology offers new features of scientific communication in pathology that cannot be obtained by conventional paper based journals. Most of these features are based upon completely open or partly directed interaction between the reader and the system that distributes the article. One of these interactions can be applied to microscopic images allowing the reader to navigate and magnify the presented images. VS and interactive Virtual Microscopy (VM) are a tool to increase the scientific value of microscopic images.</p> <p>Technology and Performance</p> <p>The open access journal Diagnostic Pathology <url>http://www.diagnosticpathology.org</url> has existed for about five years. It is a peer reviewed journal that publishes all types of scientific contributions, including original scientific work, case reports and review articles. In addition to digitized still images the authors of appropriate articles are requested to submit the underlying glass slides to an institution (DiagnomX.eu, and Leica.com) for digitalization and documentation. The images are stored in a separate image data bank which is adequately linked to the article. The normal review process is not involved. Both processes (peer review and VS acquisition) are performed contemporaneously in order to minimize a potential publication delay. VS are not provided with a DOI index (digital object identifier). The first articles that include VS were published in March 2011.</p> <p>Results and Perspectives</p> <p>Several logistic constraints had to be overcome until the first articles including VS could be published. Step by step an automated acquisition and distribution system had to be implemented to the corresponding article. The acceptance of VS by the reader is high as well as by the authors. Of specific value are the increased confidence to and reputation of authors as well as the presented information to the reader. Additional associated functions such as access to author-owned related image collections, reader-controlled automated image measurements and image transformations are in preparation.</p> <p>Virtual Slides</p> <p>The virtual slide(s) for this article can be found here: <url>http://www.diagnosticpathology.diagnomx.eu/vs/1232133347629819</url>.</p

Combined Pitch and Roll and Cybersickness in a Virtual Environment

Background: Stationary subjects who perceive visually induced illusions of self-motion, or vection, in virtual reality (VR) often experience cybersickness, the symptoms of which are similar to those experienced during motion sickness. An experiment was conducted to test the effects of single and dual-axis rotation of a virtual environment on cybersickness. It was predicted that VR displays which induced illusory dual-axis (as opposed to single-axis) self-rotations in stationary subjects would generate more sensory conflict and subsequently more cybersickness. Methods: There were 19 individuals (5 men, 14 women, mean age = 19.8 yr) who viewed the interior of a virtual cube that steadily rotated (at 60ÃÂÃÂÃÂð ÃÂÃÂÃÂ÷ sÃÂâÃÂÃÂÃÂÃÂ1) about either the pitch axis or both the pitch and roll axes simultaneously. Subjects completed the Simulator Sickness Questionnaire (SSQ) before a trial and after 5 min of stimulus viewing. Results: Post-treatment total SSQ scores and subscores for nausea, oculomotor, and disorientation were significantly higher in the dual-axis condition. Conclusions: These results support the hypothesis that a vection-inducing VR stimulus that rotates about two axes generates more cybersickness compared to a VR stimulus that rotates about only one. In the single-axis condition, sensory conflict and pseudo-Coriolis effects may have led to symptoms. However, in the dual-axis condition, not only was perceived self-motion more complex (two axes compared to one), the inducing stimulus was consistent with twice as much self-motion. Hence, the increased likelihood/magnitude of sensory conflict and pseudo-Coriolis effects may have subsequently resulted in a higher degree of cybersickness in the dual-axis condition

Vertical display oscillation effects on forward vection and simulator sickness

Background: The current study investigated the effects that vertical display oscillation had on the development of both vection and simulator sickness. Methods: Sixteen subjects were exposed to optic flow displays, which simulated either: (i) constant velocity forward self-motion (pure radial flow); or (ii) combined constant velocity forward and vertically oscillating self-motion (radial flow with vertical oscillation at one of three frequencies: 1.8, 3.7 or 7.4 Hz). During each 10-min display exposure, subjects rated the strength of their vection and 8 symptoms listed on the Subjective Symptoms of Motion Sickness (SSMS) scale at 2-min intervals. Subjects also completed the Simulator Sickness Questionnaire (SSQ) designed by Kennedy and colleagues before and after each trial, which generated a total SSQ score and three SSQ sub-scores (nausea, oculomotor symptoms, and disorientation). Results: Vertically oscillating displays (Mean = 5.51; S.D. = 2.5) were found to produce significantly stronger vection ratings than non-oscillating displays (Mean = 3.56; S.D. = 2.1). Vertically oscillating displays (Mean = 58.18; S.D. = 32.2) were also found to produce significantly more severe sickness (as rated by total SSQ scores) than non-oscillating displays (Mean = 29.67; S.D. = 24.7). Both vection and sickness symptoms increased in magnitude with prolonged exposure to optic flow. Conclusions: Our findings appear to represent a special case in visual self-motion perception, where high-frequency vertical oscillation both enhances vection and increases simulator sickness, when it is incorporated into an optic flow display simulating constant velocity self-motion in depth

Expanding and contracting optical flow patterns and simulator sickness

Background: Sensory conflict may be a factor in simulator sickness(SS) given that visual input is often inconsistent with other sensoryinputs. It was predicted that an expanding optical flow pattern wouldlead to more sensory conflict, and subsequently more SS than a contractingpattern. Methods: There were 16 individuals who participatedin the experiment (6 men, 10 women, mean age 24.4 yrs). Subjectsviewed a steadily expanding pattern of blue squares displayed on acomputer monitor. In a second condition the pattern steadily contracted.Subjects completed the Simulator Sickness Questionnaire (SSQ) designedby Kennedy and colleagues both before and after a trial (5 minexposure to optic flow). A total SSQ score and three SSQ sub-scores(nausea, oculomotor, and disorientation) were obtained. Results: Meanpost-treatment total SSQ scores (mean 28) in the expanding conditionwere higher than those obtained in the contracting condition (mean 17). Nausea and oculomotor SSQ sub-scores were also higher in theexpanding condition compared with the contracting condition. Conclusions:Experience with expanding flow patterns that result during forwardself-motion, and the sensory inputs that usually accompany them,have resulted in a central nervous system expectancy about what theappropriate inputs should be during forward self-motion. Less experiencewith backwards self-motion (and contracting patterns) may resultin a lower level of expectation regarding what the appropriate sensoryinputs should be for contracting flow patterns. This lower level of neuralexpectancy may subsequently lead to less sensory conflict and less SSgenerated by contracting flow patterns

Expanding and contracting optic-flow patterns and vection

When stationary observers view an optic-flow pattern, visually induced self-motion perception (vection) and a form of motion sickness known as simulator sickness (SS), can result. Previous results suggest that an expanding flow pattern leads to more SS than a contracting pattern. Sensory conflict, a possible cause of SS, may be more salient when an expanding optic-flow pattern is viewed. An experiment was conducted to test if a more salient sensory conflict accompanying expanding flow patterns might inhibit vection. Participants (n=15) viewed a pattern of blue squares, either steadily expanded or contracted, on a large rear-projection screen. Vection onset and magnitude were measured for 30 s with a computer-interfaced slide device. Vection onset was significantly faster, and vection magnitude stronger, when a contracting pattern was viewed. We propose that our extensive experience with forward self-motion may form a neural expectancy (exposure-history) about the sensory inputs which typically accompany expanding flow. However, since backward self-motion is less common, there may be a weaker exposure-history for contracting flow, and as a result these patterns generate less salient sensory conflict and subsequently less vection