Watch this video
Perhaps these examples of visual adaptation seem contrived, but you of course are aware of the fact that it takes some time to begin to be able to "see" in a dark room that you just stepped into. That simple experience has the heart of adaptation within it: a) The system has an adaptation timescale when the sensory capabilities are severely diminished and the system is "adapting" to a novel sensory environment, and b) that sensory systems are able to tell small differences away from the "mean" once the system has adapted.
You might still have many questions -- I hope you do (if even you wish to be inspired about how to ask questions then I would recommend watching Feynman. Here are some questions that pop into my head right away:
  1. Does the adaptation time scale depend on the "distance" between the two environments?
  2. Is sensitivity to differences truly independent of the mean?
  3. What role does attention play in the adaptation timescale or the ability to be sensitive?
... I hope you have more.