Same-Color Optical Illusion

There are lots of interesting optical illusions out there, but this one downright blows my mind. Believe it or not, the squares marked A and B in the picture below are exactly the same color. The second picture extends a bar of the same color between the two squares, so it's easier to tell. I still had to prove it to myself by opening it in Miscrosoft paint and cutting one square and putting it next to the other. Sure enough, they're the same. How is that possible, you ask? Well, according to Michael Adelson, who originally discovered this illusion in 1995, it's because our brains compensate for shadows in gauging the true color of an object. In this case, of course, the shadow isn't really a shadow, so the compensation is misleading. To read Adelson's fuller explanation, see here.