Motion 🟡 Medium
Motion Aftereffect
Stare at the spinning spiral for 20 seconds. When it stops, look at the static concentric circles to see them expand or contract.
20.0s
Look at the center of this image. Does it appear to expand or contract?
Stare Experience Verdict
Did the motion aftereffect work for you? Did you notice the static circles appear to expand or contract?
✓ Awesome! Your visual cortex adapted exactly as predicted.
Neurological Explanation: Staring at the rotating spiral fatigues direction-selective neurons in the middle temporal area (MT/V5) of your visual cortex that respond to inward rotation. When the spiral vanishes and static concentric circles are displayed, the non-adapted neurons representing outward expansion fire relatively faster. Your brain interprets this relative imbalance as actual motion, causing the static concentric circles to appear to expand outward.
✗ Keep Trying!
Troubleshooting Tips:
- Keep your gaze locked strictly on the central red dot during the entire 20-second spinning countdown.
- Try not to blink or look around, as any eye movement resets or decreases adaptation in your motion-sensitive neurons.
- Once the spiral stops, maintain your focus on the red dot. The expanding aftereffect should appear on the static concentric circles immediately.
- Ensure your screen brightness is at least 60% and sit closer to the screen.
Use the "Start Spinning" controller to run the 20-second motion-induction timer.
🎮 EXPERIENCE IT FIRST
Follow these steps to experience the Motion Aftereffect:
- Click the "Start Spinning" button to activate the rapid rotation.
- Focus your gaze entirely on the red dot at the center of the spiral. Keep your head and eyes completely still.
- When the timer hits 0s, the spiral will freeze and immediately swap to static concentric circles.
- Keep looking at the red center dot. The stationary circles will appear to expand or contract for several seconds.
🧠 THE SCIENCE
The Motion Aftereffect (MAE) is a sensory illusion experienced after staring at a moving visual pattern for a brief period (usually 20 to 30 seconds) and then focusing on a stationary target. First documented by Aristotle in his treatise Parva Naturalia, the illusion causes the stationary target to appear to move in the opposite direction of the original motion. The neurological basis for the MAE lies in the adaptation of direction-selective neurons in the middle temporal visual area (MT/V5) of the brain. When these neurons become fatigued, their resting discharge rates drop. When you shift your gaze to a static image, the non-adapted neurons representing the opposite direction fire at their standard rate, generating a phantom movement signal. This serves as key evidence of the comparative computational models used by our brains to translate light into direction.
📜 HISTORY
First described by Aristotle (350 BC). It is also commonly called the "Waterfall Illusion" because Robert Addams (1834) described it after observing the waterfall of Foyers in Scotland, noticing that rocks next to the water appeared to crawl upwards when he looked at them.