Boggle Your Mind With Optical Illusions

My mind was boggled this morning when my friend Jocelyn forwarded a dozen optical illusions. I'm not fond of these kinds of illusions because after I concentrate a while, I feel disoriented. But this particular one really caught my fancy this morning.

Stare at the four black dots in the center of the image for 30 - 60 seconds.

Then quickly close your eyes and look at something bright (like a lamp or a window
with sunlight coming through it).

You should see a white circle with an image inside it.

I've seen this image before, but not for a long time. What did you see? Makes me want to do some brain research. What in the heck happens to get these results, and who creates these kinds of things? And why?My inner critic whispers, "Why not?"