FIGURE 3.18 Illusory Contours: How Many Triangles Do You See? The Gestalt principles of perceptual organization contribute to the illusion of triangular contours in this image. When you look at this ambiguous image, you instantly reverse figure and ground so that the black circular regions become the ground while the white region is visually favored as the figure. The Gestalt principles of closure and good continuation contribute to the perceptual construction of a solid white triangle covering three black disks and an inverted triangle. The images produce a second intriguing illusion: The pure white illusory triangle seems brighter than the surrounding white paper.