Which way is the girl spinning? Clockwise or counter clockwise?
This is nothing but a two dimensional image, a comic book drawing is two dimensional, yet our minds are not programmed to view movement in such a way. So it becomes an illusion. The girl is really not spinning at all.
But in our brain, something decides that the girl is three dimensional, and we 'see' her spinning one way or another.
But don't read anything important into it, like left brain/right brain dominance. It is just fun until you realize that your very own brain lies to you to avoid you thinking it makes mistakes.
However, with some concentration, you might be able to change her direction.
It'll make you smile when you first do it.
Try, don't let your brain lie to you.
Me? I just like looking at a naked girl, even in silhouette. At least my mind is telling me she's naked.