any one of several figures that induce the perception of illusory contours defining a shape that appears to be brighter than the background. The most common example is the Kanizsa triangle, which is induced by three black circles placed as the apexes of a triangle. Each circle has a 60° wedge removed so that these wedges become the angles of the illusory triangle. Even though nothing connects the circles, a strong impression of a triangle that is brighter than the background is perceived. [Gaetano Kanizsa (1913–1993), Italian psychologist]