i naturally see it counterclockwise but can also see it go clockwise sometimes. If you're on a laptop, turn the screen upside down in it will switch directions, or at least it does for me some of the time. It works, I think, by your mind filling in the form of the woman's body. When you "see" the woman's leg going "behind" her, it really isn't, you occipital cortex is filling in that image, however when your mind is seeing it going behind her, some people's mind see it as going in front of her.