Sensory adaptation is when our senses become less sensitive to constant or repetitive stimulation. For example, when you go into a dark room after being in bright light for a while, it takes some time for your eyes to adjust.
Fatigue: Fatigue refers to the temporary loss of physical or mental energy due to excessive activity or overexertion. In terms of vision, if our eyes are tired from looking at something for too long, they may not respond as well.
Afterimage: An afterimage is an optical illusion that occurs when we continue to "see" an image even after it has been removed from our field of vision. It's like when you look at a bright light bulb for a few seconds and then close your eyes - you still see an outline of the light bulb in your mind.