Stare at the red dot for 30s, then hold the button.
Motion Direction Aftereffect
The classic 'Waterfall Illusion' implemented with high-contrast linear motion.
🧐 What do you see?▼
Stare at the red dot while the stripes move. After about 30 seconds,hold the button down to stop the motion. Even though the stripes are now stationary, they will appear to drift slowly in the opposite direction.
🧠 Why this works▼
This is the Motion Aftereffect (MAE). Our visual system processes motion using neurons tuned to specific directions (Up, Down, Left, Right).
When you stare at stripes moving right, the 'Right' detectors fire continuously and eventually fatigue. In a static image, all detectors normally fire at a low baseline rate that cancels out. But when the 'Right' ones are tired, the 'Left' ones have a relatively higher firing rate. Your brain interprets this imbalance as actual leftward movement.
🧪 Try variations▼
- Switch Direction: Use the control panel to reverse the motion. The aftereffect will also reverse!
- Variable Speed: Faster motion often leads to a more intense (though sometimes shorter-lived) aftereffect.
❓ FAQ▼
Why is it called the 'Waterfall Illusion'?
It was first documented by people staring at a falling waterfall for a long time and then looking at the static rocks next to it, which appeared to move upward.