Same color illusion

by John on December 14, 2009

Are squares A and B are the same color?

same color illusion

I found this illusion on John Baez’s site. It was created by Edward Adelson in 1995 and is the subject of a Wikipedia article.

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{ 5 comments… read them below or add one }

1 Paul 12.14.09 at 12:12: They look different to me, but I’m sure you’re going to tell me I’m wrong !
2 Daniel Lemire 12.14.09 at 12:18: Amazing.
3 John 12.14.09 at 13:07: Yep, they’re the same. I had to open it up in an image editor and drag a little patch from one square over to the other to convince myself that the colors really are the same.
4 Paul 12.14.09 at 15:34: Wow, that’s amazing! Just goes to show a lot of what we see is inferred by the brain and “filled in”. The retinal blind spot’s a good example!
5 Jared Updike 12.14.09 at 16:57: Our brains see the realistic lighting and use it to infer the surface properties of the materials on the board; when asked if the squares are the same color, we answer no. If we were given the actual physical chessboard and threw away the cylinder, clearly the paint on the two squares would in fact be different colored paint.

I’ve never seen anyone address the fact that the “trick” is really based on the loose semantics of the question “Are they the same color?” Our brains have adapted to deal with the real world around us and not gimmicks in photographs, so if that really were a physical chessboard, then those squares really would have to be painted with different colored paint. We are sort of being asked two different questions and getting penalized for answering the wrong question. Great illusion.