Eli5: Why do you see a very dark gray, but not quite black color in total darkness?

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You would think that you’d see a vantablack sort of shade or the darkest black in existence, but in total darkness, why do you see this dark gray color that isn’t quite black?

Try it. Go to a pitch-black room and open your eyes.

In: Biology

There’s actually a word for that: *eigengrau*. They believe it’s caused by photoreceptors registering false positives. Basically, even in situations where nothing is triggering any of your photoreceptors a certain percentage of them will just go ahead and fire anyway.

Is this a real thing? In a basement room- no light whatsoever it does look like vanta black to me, however after a little time it becomes similar to when my eyes are closed and I start to see different abstract colors/shapes moving around.

That’s not completely clear. There best guess is linking eigengrau to what amounts to misfiring or just random triggering of visual events. Contrast is also a factor which is of major importance to perceived brightness.

Remember that evolutionarily, there is no adaptive pressure for eyes to work flawlessly in pitch darkness (and thusly show you true absolute darkness).