Adelson’s Amazing Optical Illusion
I saw this optical illusion today and was absolutely amazed at my brain’s reaction. Look at the drawing below. Which square is darker, square A or square B?
Incredibly, the answer is that squares A and B are the same color, but your brain perceives them to be different based on surrounding color and shadow information. What’s amazing about this illusion, is that even though I now KNOW that the 2 squares are the same color, my brain continues to perceive square A as significantly darker than square B. This proof drawing helps my brain believe what my eyes aren’t seeing:
So why can’t we see the colors as they actually are, even after we’ve been told, and shown, that they’re the same? It largely has to do with our brain’s ability to interpret a 2-D drawing as a 3-D representation. We expect the cylinder to cast a shadow on the checkerboard- and because we are used to compensating for shadows in “real life” we perceive and compensate for the shadow we assume has been created by the cylinder. However, the creator of the image has manipulated the colors and the shadow to give the illusion of the shadow–without there actually being a realistically rendered or predictable shadow. In addition, because we interpret a checkerboard pattern in an expected way (alternating light and dark squares), due to the respective positions of squares A and B, our brains automatically categorize square A as a dark square and square B as a light square, despite their actual color.
We have several other mind-bending optical illusions (and an auditory one!), with explanations of the science behind what’s happening, on our Fun Brain Tricks page. What’s your favorite illusion?
image credit: Wikipedia
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August 10th, 2010 at 7:19 pm
Hello All,
My right eye was not fooled. Ha. Mike
August 11th, 2010 at 5:07 am
My favourites illusions – Escher’s artworks.. wonderful mindbending treats!