Reverse Rotation Illusion
A phenomenon where rotating objects appear to spin backwards due to stroboscopic sampling.
🧐 What do you see?▼
As the wheel accelerates, you may notice it suddenly appearing to stop or spin in the opposite direction. This is the classic "Wagon-wheel effect" often seen in movies or under fluorescent lighting.
🧠 Why this works▼
This illusion is a result of temporal aliasing. Our eyes (or the camera, or the screen refresh rate) capture "snapshots" of the world at specific intervals. If the wheel rotates almost a full 360 degrees between snapshots, it looks like it moved slightly backward instead of forward.
For example, if a spoke moves 350 degrees clockwise before the next frame is drawn, your brain interprets the shortest path: a 10-degree counter-clockwise movement.
🧪 Try variations▼
- Increase Speed: Find the "sweet spot" where the wheel seems to freeze.
- Adjust Sampling (Strobe): Lower the sampling rate to simulate a slow camera shutter or strobe light.
❓ FAQ▼
Why do car wheels look like they go backward in movies?
Cameras capture video at normally 24 frames per second. If the wheel's rotation speed syncs with this frame rate, temporal aliasing occurs.
Can this happen in real life?
Yes! Under flickering lights (like older street lamps) or even in continuous sunlight due to how our brain processes motion signals (known as "continuous wagon-wheel effect").