Lilac Chaser color

After staring at the cross in the center of this image for 20 seconds or so, you will start to see either a green dot running around the circle or a green dot circling around, seeming to erase the magenta dots on the grey background. If you shift your eyes, the magenta dots will appear again. The lilac chaser, otherwise known as the “pac-man” illusion, is primarily the effect of “negative retinal afterimage,” which occurs when our perceptual system adapts to fill in the gap left by the “afterimage” of complementary hues on a neutral background. In this case, the disappearance of lilac dots produces the appearance of afterimages of the complementary color (green). And the Gestalt effect contributes to the visual phenomenon of a flying green disk. After a while, the brain starts to integrate the successive afterimages and perceive a single flying object instead. We will delve more into the Gestalt effect later.