The challenge
Stare at the center of the image without blinking for 30 seconds. Then immediately look at a plain white wall or a blank piece of paper. What do you see?
Objective
Observe retinal afterimages and understand the photochemical basis of color vision.
Materials
Just your eyes and a plain white surface.
Description
Afterimages are a direct consequence of photoreceptor fatigue. The three types of cone cells (responding to red, green, and blue light) become temporarily depleted when overstimulated. When you shift your gaze, the depleted cones fire less, and the opposing channels dominate — producing the complementary color. This phenomenon shows that what we see is always a product of our visual system's current state, not just the light entering our eyes.
Source: https://en.wikipedia.org/wiki/Afterimage
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