We return to the internal structure of the eye in this week's laboratory. Color vision is produced by the coordination of short, medium, and long wavelength cones (blue, green and red). This variety becomes apparent when the eye has been strained by a well-illuminated color; an afterimage of another color is formed.
When one or more cones is exposed to intense light, it becomes worn out and produces an afterimage. The remaining cones then function normally and combine to produce the afterimage color. As an example, a bright yellow will wear out the green and red cones, leaving a blue afterimage from the remaining blue cones.