Spoooooooooky

This has probably been around for ages, but its worth it anyway. Try it out:

Concentrate on the four dots in the middle of the picture, for about 30 seconds.
Then tilt your head back and stare at a blank white part of the ceiling or wall.
Keep looking ... you will see a circle of light, look closer at the circle...
What do you see?

Freaky huh?