The latest internet optical illusion involves this bent ruler

The internet loves a good optical illusion, and the latest one to make people question their eyesight involves a ruler laid over some pages.

It certainly looks like the ruler is curved (to most people), although it clearly isn’t. Maybe this will help:

BUT WHY? Luckily someone put us out of our misery to explain it: it’s an example of the Hering Illusion, when two straight and parallel lines are presented in front of radial background the lines appear as if they were bowed outwards.

Here’s another example:

So there you go, it’s a perceptual distortion produced by a radiating pattern.