If you stare at the dot in the center and move your head away from the screen the rings will start to rotate. Now gradually get closer again…they change direction!
This is a classic optical illusion named after Ludimar Hermann who discovered it in 1870. At every point where the white lines intersect our eyes perceive a gray, shadowy blob. If you look directly at one of the intersections though, the blob disappears.
Stare at the image for about half a minute without moving your eyes and watch as it gradually disappears. This is a variation of Troxler’s effect which essentially says that if you fixate your eyes on a certain point, stimuli near that point will gradually fade.
The Kanizsa Triangle was named after the psychologist Gaetano Kanizsa who first described its effect. When you look at the image your brain creates contours (outlines) of a triangle although none exist. In reality it is an illusion created by the the wedges and the angles.
This is one of the most famous optical illusion pictures of an impossible object. It has two rectangular prongs at one end that morph into three cylindrical prongs at the other.