These Optical Illusions are Worth the Headache

Here are some brain-benders to liven up your Thursday morning.
They blew my mind and I hope they're interesting to you, too.

The instructions are pretty clear on this one.

For this illusion, just focus on the cross in the middle. Though all the dots are purple, it'll appear that a green dot is moving around the circle.

Last one for today.
Focus on a single image on the wall. Nothing moves. Now look around the wall. Craziness!!!

I don't know how they work, but I know that I was so fascinated that I had to keep doing them.

Anybody got some Excedrin for my headache now?