Optical illusions can take your brain for a whirl and this common one called the Pinna-Brelstaff illusion could literally make your brain spin. You can try it out by moving closer toward the circles and then quickly pulling away. You will notice that it would seem to rotate though you know it doesn’t move at all. Scientists wanted to know why this was the case, so they conducted a study on humans and macaques to figure out the underlying neurological mechanisms at play. They found that in looking at the optical illusion, the brain takes about 15 seconds to process what was happening.
(Image credit: Baingio Pinna)