|BIFOCAL ANSWER: This backgammon board consists of light and dark gray points. Look at my 2-point, the one with a red checker on it, and the unoccupied 5-point. The 2-point is a dark gray, but the 5-point is a light gray.
Wrong! The two points are identical shades of gray. Your eyes and your brain work together to try to make sense of what we see. In this case, we see the 5-point in the shadow of the cube and our brain "sees" it as lighter than it really is.
|(The optical illusion in this image is not something that will knock you over; it is small and subtle. Size doesn't matter in this case. I've shown this illusion to several co-workers, and even after being told what the illusion is they're so convinced it's impossible that they want to wager money. In some cases I had to print out the image and cut out the 2 and 5-points so they could lay them side-by-side.) -- Duane Jensen