Hering Illusion
The bowing bridge: straight lines that bend under the pressure of perspective.
🧐 What do you see?▼
Look at the two red vertical lines. Even though they are perfectly straight and vertical, they appear to bow outward at the center.
The radial background lines create a sense of depth that your brain struggles to ignore.
🧠 Why this works▼
Physiologist Ewald Hering (1861) discovered that radial patterns interfere with our ability to judge straightness.
This is likely due to temporal delay compensation. Your brain tries to "predict" the future of a moving image (perspective/looming). The radial lines simulate a vanishing point, tricking the brain into thinking the center of the image is "closer" than the edges, which distorts the geometry of the red lines.
🧪 Try variations▼
- Vary Intensity: Changing the number of radial lines affects how strong the bowing looks.
- Head Tilt: Does the bowing change if you tilt your head sideways? (Usually not, because it's a perspective-based illusion!)
❓ FAQ▼
Is this the same as the Wundt illusion?
The Wundt illusion is actually the "inverse" of the Hering illusion—if the radial lines meet at the edges instead of the center, the red lines look like they bow *inward*.