Kanizsa triangle

{| align=right The Kanizsa triangle is a famous optical illusion that was first described by the Italian psychologist Gaetano Kanizsa in 1955. In this figure we "see" a white equilateral triangle but in fact none is drawn. This effect is known as a subjective or illusory contour. Also the nonexistent white triangle appears to be brighter than the surrounding area. In fact it has the same brightness as the background.
 * [[Image:Kanizsa.jpg|thumb|right|225px|Kanizsa triangle]]

Another contour illusion is the Ehrilich illusion (2).

Motif de Kanizsa