The red flash looks "behind" the blue bar, even though they are perfectly aligned.
Flash-Lag Effect
The brain's attempt to predict the future.
🧐 What do you see?▼
Watch the moving blue bar. Periodically, a red bar flashes momentarily underneath it.
Even though the red bar is perfectly aligned with the blue bar's horizontal position at the moment of the flash, it appears to lag behind it significantly.
🧠 Why this works▼
Our brains take time to process visual signals (about 100ms). To compensate for this delay, the brain uses Motion Extrapolation.
- Continuous Motion: For the blue bar, the brain "predicts" where it will be 100ms from now and shows you that position.
- Abrupt Flash: For the red bar, there is no previous motion to extrapolate from. You see it where it *actually* was 100ms ago.
🧪 Try variations▼
Speed: At higher speeds, the distance (lag) between the blue and red bars will appear much larger. This is because the blue bar travel further in the 100ms processing window.
❓ FAQ▼
Is this useful?
Yes! This "prediction" allow athletes to hit fastballs that are moving faster than the time it takes for their visual signal to reach their brain.