Virtual reality sickness

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, headache, stomach awareness, nausea, vomiting, pallor, sweating, fatigue, drowsiness, disorientation, and apathy. Other symptoms include postural instability and retching. Virtual reality sickness is different from motion sickness in that it can be caused by the visually-induced perception of self-motion; real self-motion is not needed. It is also different from simulator sickness; non-virtual reality simulator sickness tends to be characterized by oculomotor disturbances, whereas virtual reality sickness tends to be characterized by disorientation.

Virtual reality sickness may have undesirable consequences beyond the sickness itself. For example, Crowley (1987) argued that flight simulator sickness could discourage pilots from using flight simulators, reduce the efficiency of training through distraction and the encouragement of adaptive behaviors that are unfavorable for performance, compromise ground safety or flight safety when sick and disoriented pilots leave the simulator. Similar consequences could be expected for virtual reality systems. Although the evidence for performance decrements due to virtual reality sickness is limited, research does suggest that virtual reality sickness is a major barrier to using virtual reality, indicating that virtual reality sickness may be a barrier to the effective use of training tools and rehabilitation tools in virtual reality. Estimates of the multi-study incidence and main symptoms of virtual reality sickness (also called cybersickness) have been made.

Currently, there are very few theories as to why virtual reality sickness in particular occurs; however, it is closely related to simulator and motion sickness. Sensory conflict theory provides a framework for understanding motion sickness; however, it can be applied to virtual reality sickness to better understand how it can occur, and is commonly used for that purpose. Sensory conflict theory posits that sickness will occur when a user's perception of self-motion is based on incongruent sensory inputs from the visual system, vestibular system, and non-vestibular proprioceptors, and particularly so when these inputs are at odds with the user's expectation based on prior experience. Applying this theory to virtual reality, sickness can be minimized when the sensory inputs inducing self-motion are in agreement with one another.

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