Bent Lines Illusion

The horizontal red stripes look bowed in the middle. This optical illusion brain teaser demonstrates that the black lines drawn in one-point perspective distort the red lines. You can also see that in this optical illusion, the thinner red line seems to be even more bowed than the thicker red line.

If you still don't believe that the red lines are perfectly straight, hold a peice of paper up to the screen and you'll see that they are in fact perfectly horizontal.