Take a look at the picture below. Stare at the red dot on the nose for 30 seconds. Then, look at a simple white wall or white piece of paper and take several quick blinks. What do you see?
How Does It Work?
As light enters the eyes, it falls onto the photoreceptor cells that compose the retina. The photoreceptors that detect color are called cones. The retina contains 3 types of cones. One type of cone is most sensitive to red light. A second type of cone is most sensitive to green light, and the third type of cone is most sensitive to blue light. The degree to which each type of cone is stimulated will determine what color you will perceive. For example, when you perceive the color red, it is because the red cones are very stimulated.
When you stare at a certain color for a prolonged period of time, the photoreceptors most sensitive to that color of light will become depleted and will not respond to light as well for a short period of time afterward. At this point, the information from all 3 types of cones is not in balance. You will perceive the complementary (opposite) colored "afterimage".
For example: Red and green are complementary colors. If you stare at the color red, the red photoreceptors become fatigued. Therefore, when immediately viewing a white object, it will appear less red (as these receptors are depleted) and, therefore, more green. You will view a green "after-image".
After viewing the color-inverted image above, the "after-image" will appear the true-to-life complementary colors.
Your vision quickly returns to normal as the depleted photoreceptors regenerate.
Try some more below!