I present you with two lines: AB and BC. Which one is longer? Yes, you guessed it again! You’re so smart! The lines are exactly the same… otherwise why would I be asking you a silly question like this on an optical illusion website? Actually, yes. As you click on to more illusions, you’ll see a similar illusion, and I cheat. The lines usually would appear to be straight, but I’ve adjusted them so they are not the same, just to keep your brain quick and to keep you on your toes and paying attention.
This illusion could be made even stronger if a little more perspective was brought into it, including making the A and C slightly larger, as well as making the lines not exactly the same width throughout, so that AB and AC would converge a little more before making it to B.
