That image's rotation direction has pretty much nothing to do with using one half of the brain more than other.
It's a simple illusion that can be perceived in many ways, and a lot of things affect how you perceive it. Most people see her rotating clock-wise because of the simple perspective issue that the stretched feet seems to be "higher" when it is moving from left to right, and in normal perspective (feet are lower than your eyes) that means the higher (closer to horizon) the rotating feet is, the further it is from you.
Thus it seems that since the feet is both further from you (behind the girl) and moving from left to right, the interpretation is that she's rotating clock-wise.
However, if you switch your perspective so that your viewpoint is slightly lower than the level of her feet, things become different as now the higher the foot is, the closer it appears to be - and thus the direction of rotation changes.
You can even test this by as simply as either tilting the monitor so that you view it from slight downward angle. The difference in perception is notable even with this small change.
Here's an alternate perspective:
And here's what you normally perceive (pretty much anyway...):
EDIT: Changed the order of images for better effect on the apparent perspective difference.
Sorry for the crappy animations, couldn't bother to make the background perfectly under-imposed to the character... should prove the point anyway.
Of course, I can make her legs and torso rotate to different directions, but that's pretty freaky and makes me want to call an exorcist to take the image away, but whatever.
Soo... should this test better discern whether you look at spinning women from eye level or from floor level?
Poll
