A universal feature of our sensory systems is adaptation, which means that the perceived effect of stimuli changes over time. This may happen with any of our senses and over a wide spectrum of time intervals. For example, the perceived loudness of motor noise in an aircraft or car decreases within minutes. In the case of vision, the optical system of our eyes and the photoreceptor sensitivities adapt to change perceived brightness. Over long periods of time, perceptual training can lead to adaptation; see Section 12.1. In military training simulations, sickness experienced by soldiers appears to be less than expected, perhaps due to regular exposure [173]. Anecdotally, the same seems to be true of experienced video game players. Those who have spent many hours and days in front of large screens playing first-person shooter games apparently experience less vection when locomoting themselves in VR.

Adaptation therefore becomes a crucial factor for VR. Through repeated exposure, developers may become comfortable with an experience that is nauseating to a newcomer. This gives them a terrible bias while developing an experience; recall from Section 1.1 the problem of confusing the scientist with the lab subject in the VR experiment. On the other hand, through repeated, targeted training developers may be able to improve their debugging skills by noticing flaws in the system that an ``untrained eye'' would easily miss. Common examples include:

This disconnect between the actual stimulus and one's perception of the stimulus leads to the next topic.

Steven M LaValle 2020-01-06