📐 Zöllner Illusion
Do the long black lines look like they are tilting? Adjust the red "hatches" to see the lines straighten out, or click the button to hide the trick entirely!
🧠 The Brain's Angle Bias
The long vertical lines are perfectly parallel. They do not tilt or converge at all. The reason they look crooked is because of the short red diagonal lines (hatches).
Your visual system is wired to exaggerate angles. When the red lines cross the vertical lines, your brain misinterprets the intersection points and "pushes" the vertical lines away from the hatches to make the angle look wider than it actually is. This creates the powerful illusion of a tilt!