Simulator sickness is a form of motion sickness linked to interaction with a simulated environment. It can be caused, for example, by discrepancies between the simulated motion in a simulator and the user's perception or expectation of motion. The phenomenon is often observed in users training with flight simulators and is also associated with video gaming.
The symptoms of simulator sickness include lethargy, nausea, vomiting, sweating, headaches, uneasiness, drowsiness, disorientation and ocular motor disturbances. Individuals are affected by simulator sickness to varying degrees and may experience different symptoms. Like virtual reality (VR) sickness, simulator sickness differs from motion sickness in that only visually perceived movement is required to cause its symptoms, although some simulators do include a moving cockpit. Differences between control input to reaction, between simulator movement and vehicle movement, and between tracking motion on screens as opposed to real life all contribute to simulator sickness. Another causal factor is an individual’s postural instability in dealing with perceived and actual simulator movement.
The resemblance of looking around in a simulator compared to a real life experience allows the technology to convince the human brain that the represented environment is real. That capacity is also provided by augmented reality (AR) and VR environments. In both types of simulated experiences, small discrepancies in movement, lag and changes of frame rates remain. These differences can cause side effects similar to physical motion sickness. Head tracking lag and lower refresh rates on screens, in particular, can contribute to virtual reality sickness, resulting in disorientation, headaches and nausea.
Due to its long-standing use of simulators for training, the United States Navy is considered an authority on simulation and simulator sickness. The US Navy created the Simulator Sickness Questionnaire, which gathers and ranks different symptoms. The questionnaire makes for a more subjective ranking of degrees of simulator sickness. To reduce simulator sickness, it can help to reduce training times to 20-minute stints.
Many users of simulators experience the symptoms less under continuous regular exposure over time. In fact, more hours of real-world piloting has been found to be a predicting factor for the occurrence of simulator sickness. Real-world pilots often experience symptoms, while those with less or no real flight experience are not as likely to feel ill from simulations.
Watch an introductory video about simulator sickness: