Stare at the red dot for 30s. The left side is much more intense.
Contrast Adaptation Illusion
A subtle demonstration of gain control in the human visual system.
🧐 What do you see?▼
In the adaptation phase, the left side has a very high-contrast black/white pattern. After 30 seconds of staring at the red dot, swich to the test phase.The pattern on the left will look much fainter or lower in contrast than the one on the right, even though they are now identical.
🧠 Why this works▼
This is called Contrast Gain Control. Your brain constantly adjusts its sensitivity to the level of detail/contrast in your environment.
By staring at a high-contrast pattern, you are telling your brain 'There is plenty of signal here, you can turn down the volume.' The 'volume' (gain) of your contrast detectors on that side of the retina is lowered. When you look at a low-contrast pattern afterwards, your 'volume' is still turned down, so the pattern looks even fainter.
🧪 Try variations▼
- Intensity Shift: Use the Intensity slider to mute the contrast of the patterns and see how it affects the adaptation strength.
- Time: Staring for shorter periods (10s vs 60s) will show you how quickly this gain control system operates.
❓ FAQ▼
Is this why everything looks weird after being in bright sunlight?
Exactly. Your eyes adapt to high light levels and high contrast environments, so moving into a dimly lit room makes everything feel 'washed out' until your gain control resets.