Complementary colors directly cause the colors you see in negative afterimages; specifically, the color of an afterimage is typically the complementary color of the stimulus that caused it.
Here's a breakdown of the relationship:
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What are Complementary Colors? Complementary colors are pairs of colors that, when combined, cancel each other out to produce a neutral color like white or gray. Examples include red and green, blue and yellow, and orange and cyan.
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What are Afterimages? Afterimages are visual sensations that persist after the initial stimulus has been removed. Staring at an image and then looking at a white surface often produces an afterimage.
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The Connection: When you stare at a color for an extended period, the photoreceptors in your eyes that are sensitive to that color become fatigued or overstimulated. When you then look at a neutral surface (like a white wall), those fatigued receptors respond less strongly, while the receptors sensitive to the complementary color are relatively more active. This imbalance creates the illusion of seeing the complementary color in the afterimage.
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Example: If you stare at a red object, the red-sensitive cones in your eyes become fatigued. When you shift your gaze to a white surface, the green-sensitive cones (green being red's complement) are relatively more active, resulting in a green afterimage.
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Negative Afterimages: The type of afterimage described above, where the color is inverted to its complement, is known as a negative afterimage. They are also characterized by reversed lightness/darkness (dark areas appear light and vice versa).
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Positive Afterimages: Positive afterimages are brief and appear in the same color as the original stimulus, but they are less relevant to the specific question about complementary colors. They occur immediately after stimulus removal.
Therefore, the colors you perceive in a negative afterimage directly reflect the complementary color of the original stimulus due to the differential fatigue and activity of color-sensitive photoreceptors in your eyes.
