Right Brain vs. Left Brain

I can not for the life of me figure this article thing out. My dad emailed it to me a couple of days ago & I sat entranced by it. How does it work? I'm totally at a loss. I made Scott wake up from his nap and test it with me so I could see if it worked. So, it is this picture of a woman spinning depending on which side of your brain is dominate it effects which way the woman is spinning. She spins clockwise to me. But for Scott she spins counterclockwise. But it can switch back and forth sometimes for me. Weird! Take a look at the link and let me know what it does for you! Even if you get two people sitting side by side it will look differently for each person.