Awesome Optical Illusion

Found this one on Scientific American online. Before yesterday, I haven't seen this particular one before, and it's continuously boggled me since.
Most optical illusions are simple tricks that I can undo if I try hard enough or stare at the right place, but this one I simply cannot undo.
Look at this picture in it's entirety (don't let any part of it get cut off). Take note that squares A and B are the EXACT same shade of gray. If you don't believe it, print it out (or photoshop it) to cut out those two squares and place them next to each other.

Most optical illusions are simple tricks that I can undo if I try hard enough or stare at the right place, but this one I simply cannot undo.
Look at this picture in it's entirety (don't let any part of it get cut off). Take note that squares A and B are the EXACT same shade of gray. If you don't believe it, print it out (or photoshop it) to cut out those two squares and place them next to each other.
