The optical illusion challenge asks players to determine which of two lines is longer in just 10 seconds.

Optical illusions play tricks on your brain and can make you see things that aren't really there, from static images swirling around the page to images that stay with you even after you look away.

The famous Ebbinghaus illusion, named for its discoverer, the German psychologist Hermann Ebbinghaus (1850–1909). Despite appearances, the two orange circles are the same size. Have you ever looked at ...