Stare at the black dot in the center of this image. Slowly move your head toward the image and then away from it. The circles should appear to rotate. This happens because the pattern confuses certain cells in your brain that are responsible for interpreting lines and curves. The result is an illusion that the circles are moving.
Illustration by Illusionworks, L.L.C.
Vision scientist Al Seckel is the author of The Great Book of Optical Illusions.
