system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it that when you're in a "dark" room and you focus on a really dark spot everything around you (even light) starts to fade away?

I know I probably didn't make any sense since it's hard to explain but imagine being in a dark room with nothing but a little red LED light in the center of the room if you focus on a really dark corner, the light will start fading away into darkness. Why is that?
gpt
ELI5 Answer: Your eyes see things by seeing changes. When nothing changes, we can't see anymore.

Complicated answer: Image burn-in. Humans see light as an "excitement" of the cones and rods in our eyes. If we continue to stare at the same image without it changing, the excitement ends even though the image does not. If you stare at anything for a while, you will notice that your peripheral vision starts to fade and eventually your primary vision starts to fuck up as well.