Smithsonian.com

Do you see moving circles? (A. Kitaoka 2003)

The image above is not an animation. It’s just a static picture. But the movement, at least to your visual system, is real, conclude a group of researchers in Japan in their recent study in the Journal of Vision. (The journal seems to have a yen for optical illusions; just take a look at their online table of contents.) The scientists used functional magnetic resonance imaging to measure the brain activity of people as they gazed at the illusion, called Rotating Snakes. They expected the scans to show activity in parts of the brain that handle higher-level cognition, that is, they expected to see active imagination. Instead, a low-level part of the visual cortex, one that processes physical movement, lit up with activity. The researchers believe that the illusion, therefore, “is related to some component of eye movements.”

(Many thanks to blog overseer and office neuroscience expert Laura for help with this post.)