““The human brain can be compared to a modern flight simulator in several respects. Like a flight simulator, it constructs and continuously updates an internal model of external reality by using a continuous stream of input supplied by the sensory organs and employing past experience as a filter. It integrates sensory-input channels into a global model of reality, and it does so in real time. However, there is a difference. The global model of reality constructed by our brain is updated at such great speed and with such reliability that we generally do not experience it as a model. For us, phenomenal reality is not a simulational space constructed by our brains; in a direct and experientially untranscendable manner, it is the world we live in. Its virtuality is hidden, whereas a flight simulator is easily recognized as a flight simulator—its images always seem artificial. This is so because our brains continuously supply us with a much better reference model of the world than does the computer controlling the flight simulator. The images generated by our visual cortex are updated much faster and more accurately than the images appearing in a head-mounted display. The same is true for our proprioceptive and kinesthetic perceptions; the movements generated by a seat shaker can never be as accurate and as rich in detail as our own sensory perceptions.””