Virtual reality sickness (VR motion sickness) is the physical discomfort that occurs when an end user's brain receives conflicting signals about self-movement in a digital environment. While the exact number of people who will be affected by VR motion sickness cannot be known in advance, software engineers who develop VR and augmented reality (AR) environments typically assume that 25% of viewers will experience VR motion sickness. This is the same percentage of people who experience motion sickness on an airplane while traveling through low altitude turbulence.There are several theories about the root causes of VR motion sickness and differences in how individuals use vision to maintain their balance may be one contributing element. The biggest contributing factor, however, is thought to be caused by the sensory conflicts that send confusing messages to the brain. This is because even though the person's eyes may say they are walking around a virtual world, their body will tell them that they are actually sitting down and those conflicting sensory signals cause a feeling of illness. Current research indicates that gender and age may also play an important role in determining who may fall victim to VR motion sickness. For example, woman are more likely to be affected than men. While some researchers believe this is because women lag behind men in the consumption of virtual reality programming, other researchers believe that women are more likely to get sick from VR because they have better peripheral vision than men and require a larger field of view (FOV) to avoid motion sickness. Different ages and stages in life may also determine if a user will be affected by VR sickness. Genetics are also thought to play a role in determining who will be affected by VR motion sickness. If a person's family exhibits migraines, inner ear conditions, problems with sight, or past experiences with motion sickness, then it is likely the offspring will be genetically predisposed to suffer in the same way.