Simulator sickness

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Simulator sickness is a subset of motion sickness that is typically experienced while playing video games from first-person perspective. It was discovered in the context of aircraft pilots who undergo training for extended periods of time in flight simulators. Due to the spatial limitations imposed on these simulators, perceived discrepancies between the motion of the simulator and that of the vehicle can occur and lead to simulator sickness. It is similar to motion sickness in many ways, but occurs in simulated environments and can be induced without actual motion. Symptoms of simulator sickness include discomfort, apathy, drowsiness, disorientation, fatigue, and nausea. These symptoms can reduce the effectiveness of simulators in flight training and result in systematic consequences such as decreased simulator use, compromised training, ground safety, and flight safety. Pilots are less likely to want to repeat the experience in a simulator if they have suffered from simulator sickness and hence can reduce the number of potential users. It can also compromise training in two safety-critical ways:

Contents

  1. It can distract the pilot during training sessions.
  2. It can cause the pilot to adopt certain counterproductive behaviors to prevent symptoms from occurring.

Simulator sickness can also have post-training effects that can compromise safety after the simulator session, such as when the pilots drive away from the facility or fly while experiencing symptoms of simulator sickness.

Origins

Though human-piloted aviation has existed since the early 20th century, simulator sickness did not arise as an issue for pilots until much later when the first fixed-base simulators were created. [1] Bell Aircraft created a helicopter simulator for the Navy during the 1950s, and it was found "that a large number of observers (mostly helicopter pilots) experienced some degree of vertigo during these demonstrations". Navy psychologists performed further study on the pilots who participated in these simulator exercises, and found that 28 out of 36 respondents to their evaluations experienced sickness. Additionally, psychologists found that experienced flight instructors seemed to be most susceptible. In fact, 60% of the instructors reported simulator sickness symptoms compared to only 12% of the students. "The SS usually occurred in the first ten minutes of a training session and frequently lasted for several hours afterward." [1]

Two main theories exist about the causes of simulator sickness. [1] The first is sensory conflict theory. Optical flow patterns generated in virtual environments typically induce perception of self-motion (i.e., vection). Sensory conflict theory holds that, when this perception of self-motion is not corroborated by inertial forces transmitted through the vestibular system, simulator sickness is likely to occur. Thus, sensory conflict theory predicts that keeping the visual and vestibular inputs in agreement can reduce the likelihood of simulator sickness experienced by users. [1] Additionally, according to this theory, people who do not have a functioning vestibular component of their nervous system should not show either simulator sickness or motion sickness.

The second theory for simulator sickness identifies postural instability as the determinant of simulator sickness. This theory notes that situations producing simulator sickness are denoted by their unfamiliarity to the participant more than the degree of sensory conflict; for example, sea sickness is, for many, a transient problem that is solved with experience to being on a ship. Thus, the novelty of the motion cues is hypothesized to lead to an inability to maintain postural control and this lack of control causes simulator sickness until the participant adapts. Key attributes here include the notation that the motions causing simulator sickness are in a nauseogenic low frequency range that overlaps with the frequency of motion within the human body as it maintains control over its posture. Experiments have measured markers of the onset of postural instability, and found that it precedes signs and symptoms of simulator sickness. [2]

At present, it is accurate to say that both—and neither—of these theories are yet adequate to fully explain and predict simulator sickness. Although it is clear which types of pilots are affected by it, and both sensory conflict theory and postural instability theory relate its onset with certain physiological conflicts, neither theory suffices to predict why these specific conflicts (vision vs. vestibular on the one hand, posture vs. control on the other) elicit sickness in the subject. Additional possibilities for elicitation of motion sickness in general (including simulator sickness) include gaze destabilization, which is disrupted if the vestibuloocular reflex gain in the nervous system is altered, moving patterns [3] of visual stimuli, and motions that stimulate the otoliths and semicircular canals of the inner ear. It is unclear whether or not these stimuli are encountered in significant amounts in a simulator to induce sickness in the expert pilots. However, since laboratory studies have shown the removal of the vestibular projection areas of the cerebellum (in laboratory animals) to result in insusceptibility to motion sickness, it is almost certainly probable that the first of these theories holds the most promise with regard to research into the direct physiological causes of the phenomenon. [4]

Effect of experience in the real and simulated environments

While anyone can experience simulator sickness, studies in flight simulators have found a correlation between the appearance of symptoms and the flight experience of the pilot. Studies conducted independently by the US Navy, US Coast Guard, and US Army during the 1980s all came to the same conclusion: the greater experience of the pilot, the higher the likelihood of sickness symptoms during simulation training exercises.[ citation needed ]

In 1989, the US Army released a report detailing the results of a study examining simulator sickness in UH-60 Blackhawk flight simulators, confirming the above hypothesis. [5] The report also found that longer periods between sessions of flight simulation training resulted in greater probability of detrimental symptoms appearing increased.

Research suggests that this is the body's natural way of adjusting to these systems. The bodies of experienced pilots have adapted to different types of motion experienced during actual flight conditions. When placed into a flight simulator, visual and other stimuli cause their bodies to expect the same motions associated with actual flight conditions. However, their bodies instead experience the imperfect motion of the simulator, resulting in sickness.

A similar situation can arise for pilots who have long gaps between simulator uses. During simulation training, the body will eventually adapt to the environment to diminish the effects of simulator sickness. However, when long periods of time are spent outside of the simulator, the body is not able to adequately adapt and symptoms will reappear. [5]

Often, adaptation is the single most effective solution to simulator sickness. For most individuals, adaptation can occur within only a few sessions, with only a minority of individuals (3–5 percent) never being able to adapt. This adaptation occurs within the psyche of the individual with repeated, controlled exposures, without any required alteration to the simulator. Through incremental exposures, dispersed regularly over a series of days, adaptation can occur faster than that of an abrupt all-encompassing exposure. However, following adaptation to the novel simulator motion environment, simulator sickness symptoms can reoccur with a return to the former environment. For this reason, simulator sickness is commonly referred to as a phenomenon of maladaptation sickness, due to incessant conflict between current and past environmental conditions. [1] In flight training, this phenomenon can be a safety concern where it may lead to motion sickness hindering pilot performance in the real aircraft following flight simulator training.

Measurement

The Simulator Sickness Questionnaire (SSQ) is currently the standard for measuring simulator sickness. The SSQ was developed based upon 1,119 pairs of pre-exposure/post-exposure scores from data that were collected and reported earlier. [6] [7] These data were collected from 10 Navy flight simulators representing both fixed-wing and rotary-wing aircraft. The simulators selected were both 6-DOF motion and fixed-base models, and also represented a variety of visual display technologies. The SSQ was developed and validated with data from pilots who reported to simulator training healthy and fit.

The SSQ is a self-report symptom checklist. It includes 16 symptoms that are associated with simulator sickness. Participants indicate the level of severity of these symptoms that they are experiencing currently. For each symptom there are four levels of severity (none, slight, moderate, severe). The SSQ provides a Total Severity score as well as scores for three subscales (Nausea, Oculomotor, and Disorientation). The Total Severity score is a composite created from the three subscales. It is the best single measure because it provides an index of the overall symptoms. The three subscales provide diagnostic information about particular symptom categories:

The three subscales are not orthogonal to one another. There is a general factor common to all of them. Nonetheless, the subscales provide differential information about participants' experience of symptoms and are useful for determining the particular pattern of discomfort produced by a given simulator. All scores have as their lowest level a natural zero (no symptoms) and increase with increasing symptoms reported. [4]

In some cases, the Motion Sickness Assessment Questionnaire (MSAQ) has also been used to evaluate simulator sickness, despite its focus on motion sickness. [8]

Gaming motion sickness

Many video gamers, notably the late John Peter "TotalBiscuit" Bain, [9] report motion sickness while playing games with a narrow field of view (FOV). [10] [11] [12] Depending on screen size and distance, FOV settings of generally 90 to 110 degrees may be good for close up (PC gaming) and 60 to 75 degrees for further away (console gaming). [13] [14] A small but significant amount of gamers are affected if FOV is not set properly. [15] [16] Other factors and settings such as motion blur and head bobbing may also affect player discomfort. [17] [18]

Related Research Articles

<span class="mw-page-title-main">Motion sickness</span> Nausea caused by motion or perceived motion

Motion sickness occurs due to a difference between actual and expected motion. Symptoms commonly include nausea, vomiting, cold sweat, headache, dizziness, tiredness, loss of appetite, and increased salivation. Complications may rarely include dehydration, electrolyte problems, or a lower esophageal tear.

A balance disorder is a disturbance that causes an individual to feel unsteady, for example when standing or walking. It may be accompanied by feelings of giddiness, or wooziness, or having a sensation of movement, spinning, or floating. Balance is the result of several body systems working together: the visual system (eyes), vestibular system (ears) and proprioception. Degeneration or loss of function in any of these systems can lead to balance deficits.

<span class="mw-page-title-main">Acrophobia</span> Extreme fear of heights

Acrophobia, also known as hypsophobia, is an extreme or irrational fear or phobia of heights, especially when one is not particularly high up. It belongs to a category of specific phobias, called space and motion discomfort, that share similar causes and options for treatment.

<span class="mw-page-title-main">Vestibular system</span> Sensory system that facilitates body balance

The vestibular system, in vertebrates, is a sensory system that creates the sense of balance and spatial orientation for the purpose of coordinating movement with balance. Together with the cochlea, a part of the auditory system, it constitutes the labyrinth of the inner ear in most mammals.

<span class="mw-page-title-main">Space adaptation syndrome</span> Condition caused by weightlessness

Space adaptation syndrome (SAS) or space sickness is a condition experienced by as many as half of all space travelers during their adaptation to weightlessness once in orbit. It is the opposite of terrestrial motion sickness since it occurs when the environment and the person appear visually to be in motion relative to one another even though there is no corresponding sensation of bodily movement originating from the vestibular system.

<span class="mw-page-title-main">Dizziness</span> Neurological condition causing impairment in spatial perception and stability

Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to disequilibrium or a non-specific feeling, such as giddiness or foolishness.

Spatial disorientation is the inability to determine position or relative motion, commonly occurring during periods of challenging visibility, since vision is the dominant sense for orientation. The auditory system, vestibular system, and proprioceptive system collectively work to coordinate movement with balance, and can also create illusory nonvisual sensations, resulting in spatial disorientation in the absence of strong visual cues.

<span class="mw-page-title-main">Labyrinthitis</span> Medical condition

Labyrinthitis is inflammation of the labyrinth, a maze of fluid-filled channels in the inner ear. Vestibular neuritis is inflammation of the vestibular nerve. Both conditions involve inflammation of the inner ear. Labyrinths that house the vestibular system sense changes in the head's position or the head's motion. Inflammation of these inner ear parts results in a vertigo and also possible hearing loss or tinnitus. It can occur as a single attack, a series of attacks, or a persistent condition that diminishes over three to six weeks. It may be associated with nausea, vomiting, and eye nystagmus.

Airsickness is a specific form of motion sickness which is induced by air travel and is considered a normal response in healthy individuals. Airsickness occurs when the central nervous system receives conflicting messages from the body affecting balance and equilibrium. Whereas commercial airline passengers may simply feel poorly, the effect of airsickness on military aircrew may lead to a decrement in performance and adversely affect the mission.

<span class="mw-page-title-main">Motion simulator</span> Type of mechanism

A motion simulator or motion platform is a mechanism that creates the feelings of being in a real motion environment. In a simulator, the movement is synchronised with a visual display of the outside world (OTW) scene. Motion platforms can provide movement in all of the six degrees of freedom (DOF) that can be experienced by an object that is free to move, such as an aircraft or spacecraft:. These are the three rotational degrees of freedom and three translational or linear degrees of freedom.

<span class="mw-page-title-main">Vertigo</span> Type of dizziness where a person has the sensation of moving or surrounding objects moving

Vertigo is a condition in which a person has the sensation that they are moving, or that objects around them are moving, when they are not. Often it feels like a spinning or swaying movement. It may be associated with nausea, vomiting, perspiration, or difficulties walking. It is typically worse when the head is moved. Vertigo is the most common type of dizziness.

<span class="mw-page-title-main">Bárány chair</span> Device used for aerospace physiology training

The Barany chair or Bárány chair is a device used for aerospace physiology training, particularly for student pilots.

Flicker vertigo, sometimes called the Bucha effect, is "an imbalance in brain-cell activity caused by exposure to low-frequency flickering of a relatively bright light." It is a disorientation-, vertigo-, and nausea-inducing effect of a strobe light flashing at 1 Hz to 20 Hz, approximately the frequency of human brainwaves. The effects are similar to seizures caused by epilepsy, but are not restricted to people with histories of epilepsy.

The sopite syndrome is a neurological disorder that relates symptoms of fatigue, drowsiness, and mood changes to prolonged periods of motion. The sopite syndrome has been attributed to motion-induced drowsiness such as that experienced by a baby when rocked. Researchers Ashton Graybiel and James Knepton at the US Naval Aerospace Medical Research Laboratory first used the term "the sopite syndrome" in 1976, to refer to the sometimes sole manifestation of motion sickness, though other researchers have referred to it as "Sopite syndrome."

<span class="mw-page-title-main">Illusions of self-motion</span> Misperception of ones location or movement

Illusions of self-motion occur when one perceives bodily motion despite no movement taking place. One can experience illusory movements of the whole body or of individual body parts, such as arms or legs.

In psychophysical perception, the Coriolis effect is the misperception of body orientation due to head movement while under the effect of rotation, often inducing nausea. This effect comes about as the head is moved in contrary or similar motion with the body during the time of a spin. This goes on to affect the vestibular system, particularly the semicircular canals which are affected by the acceleration. This causes a sense of dizziness or nausea before equilibrium is restored after the head returns to a stabilized state. Crucially, this illusion is based entirely upon perception, and is largely due to conflicting signals between one's sight and one's perception of their body position or motion. Examples of situations where this can arise are circular acceleration and movement during a circular rotation.

Space neuroscience or astroneuroscience is the scientific study of the central nervous system (CNS) functions during spaceflight. Living systems can integrate the inputs from the senses to navigate in their environment and to coordinate posture, locomotion, and eye movements. Gravity has a fundamental role in controlling these functions. In weightlessness during spaceflight, integrating the sensory inputs and coordinating motor responses is harder to do because gravity is no longer sensed during free-fall. For example, the otolith organs of the vestibular system no longer signal head tilt relative to gravity when standing. However, they can still sense head translation during body motion. Ambiguities and changes in how the gravitational input is processed can lead to potential errors in perception, which affects spatial orientation and mental representation. Dysfunctions of the vestibular system are common during and immediately after spaceflight, such as space motion sickness in orbit and balance disorders after return to Earth.

The health effects of 3D are the aspects in which the human body is altered after the exposure of three-dimensional (3D) graphics. These health effects typically only occur when viewing stereoscopic, autostereoscopic, and multiscopic displays. Newer types of 3D displays like light field or holographic displays do not cause the same health effects. The viewing of 3D stereoscopic stimuli can cause symptoms related to vision disorders that the individual already had, as a person with a healthy binocular vision shouldn't experience any side effects under three-dimensional exposure.

Virtual reality sickness occurs when exposure to a virtual environment causes symptoms that are similar to motion sickness symptoms. The most common symptoms are general discomfort, eye strain, headache, stomach awareness, nausea, vomiting, pallor, sweating, fatigue, drowsiness, disorientation, and apathy. Other symptoms include postural instability and retching. Common causes are low frame rate, input lag, and the vergence-accommodation-conflict.

<span class="mw-page-title-main">Vestibular rehabilitation</span> Form of physical therapy for vestibular disorders

Vestibular rehabilitation (VR), also known as vestibular rehabilitation therapy (VRT), is a specialized form of physical therapy used to treat vestibular disorders or symptoms, characterized by dizziness, vertigo, imbalance, posture, and vision. These primary symptoms can result in secondary symptoms such as nausea, fatigue, and difficulty concentrating. Symptoms of vestibular dysfunction can significantly decrease quality of life, introducing mental-emotional issues such as anxiety and depression, and greatly impair an individual, causing them to become more sedentary. Decreased mobility can result in weaker muscles, less flexible joints, and worsened stamina, as well as decreased social and occupational activity. Vestibular rehabilitation therapy can be used in conjunction with cognitive behavioral therapy in order to reduce anxiety and depression resulting from a change in lifestyle.

References

  1. 1 2 3 4 5 Johnson, David. "Introduction to and Review of Simulator Sickness Research" (PDF). Research Report 1832. U.S. Army Research Institute for the Behavioral and Social Sciences. Archived (PDF) from the original on November 7, 2014. Retrieved 14 April 2014.
  2. ↑ Stoffregen, T.A.; Hettinger, L.J.; Haas, M.W.; Roe, M.M.; Smart, L.J. (2000). "Postural Instability and Motion Sickness in a Fixed-Base Flight Simulator". Human Factors. 42 (3): 458–469. doi:10.1518/001872000779698097. PMID   11132807. S2CID   30662436.
  3. ↑ "Combating VR Sickness: Debunking Myths And Learning What Really Works". ARVI Games.
  4. 1 2 James R. Lackner, Motion Sickness, http://www.brandeis.edu/graybiel/publications/docs/190_ms_encns.pdf. Retrieved 14 April 2014.
  5. 1 2 Gower, D.W. (1989). Simulator Sickness in the UH-60 (Black Hawk) Flight Simulator), USAARL Report No. 89-25 (PDF). United States Army Aeromedical Research Laboratory.
  6. ↑ Beltzley, D.R.; Kennedy, R.S.; Berbaum, K.S.; Lilienthal, M.G.; Gower, D.W. (1989). "The time course of postflight simulator sickness symptoms". Aviation, Space, and Environmental Medicine. 60 (11): 1043–1048. PMID   2818393.
  7. ↑ Kennedy, R.S.; Lane, N.E.; Berbaum, K.S.; Lilienthal, M.G. (1993). "Simulator sickness questionnaire: An enhanced method for quantifying simulator sickness". The International Journal of Aviation Psychology. 3 (3): 203–220. doi:10.1207/s15327108ijap0303_3.
  8. ↑ Brooks, Johnell O.; Goodenough, Richard R.; Crisler, Matthew C.; Klein, Nathan D.; Alley, Rebecca L.; Koon, Beatrice L.; Logan, William C.; Ogle, Jennifer H.; Tyrrell, Richard A.; Wills, Rebekkah F. (2010-05-01). "Simulator sickness during driving simulation studies". Accident Analysis & Prevention. 42 (3): 788–796. doi:10.1016/j.aap.2009.04.013. ISSN   0001-4575. PMID   20380904.
  9. ↑ "In defense of asset flips on Steam". 12 July 2018.
  10. ↑ "TotalBiscuit: A Gaming YouTuber Who Championed the Rights of Consumers".
  11. ↑ "Splatoon 2 Designer Explains Why the Maps Rotate and Salmon Run is Time-Limited". 6 September 2017.
  12. ↑ "Motion Sickness in Video Games - is It Normal?". 25 October 2021.
  13. ↑ "Game accessibility guidelines | if the game uses field of view (3D engine only), set an appropriate default for the expected viewing environment".
  14. ↑ "How to Stop Getting Motion Sickness Playing Video Games". 11 February 2020.
  15. ↑ "Splatoon 2 Designer Explains Why the Maps Rotate and Salmon Run is Time-Limited". 6 September 2017.
  16. ↑ "Why Video Games Make You Feel Sick (And What You Can do About It)". 8 February 2016.
  17. ↑ "Cure Motion Sickness of Video Games Stop Headaches 2022". 29 July 2022.
  18. ↑ "Why do video games make some people feel sick?". 22 November 2021.
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