Suppose someone stares at an illustration of the American flag for a while and then glances at a blank white page. Why do the red stripes look green when the person glances at the blank page?

Question

Quizplus · Accepted Answer

Opponent-process cells in the retina respond in opposite ways to different colors of light, producing pairs of opponent colors (e.g. red vs. green, blue vs. yellow). Staring at an image with red stripes for a while fatigues the opponent-process cells that respond to red light. When the person looks at a blank white page, the cells that are still active respond more strongly to the opponent color, green, leading to the perception of green stripes.

Suppose Someone Stares at an Illustration of the American Flag