[Xurinos]

My guess: The object that does not reflect light to you ceases to exist in your vision. Nothing comes from that direction. Your brain would then attempt to compensate -- as it does for the blind spot in both your eyes -- and fill in the void, perhaps with a fuzzy version of continuity of whatever colors and textures surround the object.

[jerf]

We don't need to make wild hypotheses about what an object that doesn't reflect light looks like. It's so mundane we have a word for it: "black".

[TallGuyShort]

It would look black to a light sensor. As he says, your brain does play tricks and fill-in-the-black more than you might think. If you have a blind-spot you don't always perceive the absence of light - you may perceive what your brain is expecting. There are also disorders where it does this too much. I knew a guy who used to do things like overfill his coffee mug all the time, because the mug kept looking empty and then suddenly it was overflowing - his brain just expected the mug to stay empty.

[jerf]

A thing that absorbs light is not a "blind spot". It's black.

Are you on the good stuff or something? It's black. Just because someone muttered "quantum" does not make this magic. It's black. What is so complicated about this concept? It literally can not get much more normal than this.

[TallGuyShort]

I never implied anything to do with quantum physics or "magic". I also never said it wasn't black or an absence of light. Both I and the GP comment are referring to how your brain fills in the gaps and causes you to think you see things that are not there. So no light reaches you eye, yes, and that is referred to as being "black". We're talking about what your brain would then cause you to perceive or "see". Now what is so complicated about that?

[jerf]

"The object that does not reflect light to you ceases to exist in your vision. Nothing comes from that direction. Your brain would then attempt to compensate -- as it does for the blind spot in both your eyes -- and fill in the void, perhaps with a fuzzy version of continuity of whatever colors and textures surround the object."

This is gibberish. Unless you're high on acid, when you see a black thing, your visual system does not go nuts trying to fill in the missing data... it sees black.

You're trying to explain a phenomenon that doesn't exist. Your brain does not see a black object as a "gap"... it sees it as black. There's nothing complicated to explain here. There's no "illusion". There's no weird perceptual thing to explain, beyond the usual "what is seeing red, really?" (red for some reason being the usual color chosen for this question), which is clearly not what is being referenced. There's no gap here. No optical illusion. Just black.

I mean, find something in your visual field that is black, and look at it for a bit. Do you see your brain "filling in the void, perhaps with a fuzzy version of continuity of whatever colors and textures surround the object"?

The only hard thing about understanding this is that there's no hard thing.

[bobbles]

It would be interesting to see some ultrablack material in person http://www.wired.com/wiredscience/2009/03/ultrablack/

[d23]

Wouldn't it just be dark? I think the blind spot is a different phenomenon. This would be no different than being in a pitch black room.

[Xurinos]

Maybe the critical question is: If no light at all comes from the object, is that the same as it being dark, or is it a complete lack of stimulus?

If the brain receives noise, it fills in the blanks (http://www.sciencedaily.com/releases/2000/06/000601164617.ht...). In sensory deprivation, the brain also fills in the blanks (would cite but ended up finding a ton of supporting material in a web search, including an interesting study about the effects of anxiety on amount of hallucinations).