So this is the strangest optical illusion I’ve ever seen. First, I’ll let you get an unanchored look at it:

Is she spinning clockwise or counterclockwise? Most of us would say counter, I assume. But if you look at it for a while, you may start to see her spinning in the other direction. If you see it as clockwise, you may be using more right-brain functions. If counter, left brain.

At first, I thought it was a trick, then I was able to get it to switch and switch back after some struggling. This isn’t a trick. Link to where it was found, via kottke.