Optical Illusion: Are these lines straight or do they bend

The cafe wall optical illusion posted on Twitter challenges people to figure out if the lines are straight or bend at an angle.  | Trending

HOW TO DRAW CURVED LINES USING STRAIGHT LINES – EASY OPTICAL ILLUSION SPIRAL PATTERN

30 Optical Illusions That Will Make Your Brain Hurt

How do optical illusions work?

Hering illusion - Wikipedia

Straight Lines That Curve, Circles That Twist and Other Mind-Bending Illusions

Can you make your brain *not* see this circle illusion?

Optical illusions

Line Illusions

Optical illusions: Are these lines straight or bent? Latest brain teaser puzzle

25 Optical Illusions That Prove Your Brain Sucks