Stare at the red dot for 30s...
Orientation Aftereffect
A subtle but powerful demonstration of how your brain's orientation detectors get 'tired'.
🧐 What do you see?▼
Stare at the red dot in the center of the tilted lines for about 30 seconds. Then, click the button to switch to the vertical test lines.The vertical lines will suddenly appear to tilt in the opposite direction!
🧠 Why this works▼
This is the Tilt Aftereffect. In the primary visual cortex (V1), neurons are 'tuned' to specific orientations. Some fire for vertical lines, some for horizontal, and some for specific angles.
When you stare at lines tilted at 20 degrees, the neurons tuned to that angle become fatigued (their response rate drops). When you then look at perfectly vertical lines, the vertical-tuned neurons are competing with the 'tired' 20-degree neurons. This shifts the population average of the neural signal, tricking your brain into perceiving a tilt where none exists.
🧪 Try variations▼
- Switch Direction: Tilt the adaptation lines the other way and notice the aftereffect also reverses.
- Higher Intensity: Increases the density of the lines, which can make the neural fatigue more uniform.
❓ FAQ▼
How long does it take to adapt?
Most people see a clear effect after 20-30 seconds of solid fixation.