I received an email sharing the spinning dancer optical illusion (also called the "spinning lady"). Supposedly, the way the dancer "spins" tells you whether you favor your right or left brain. If she spins clockwise, you supposedly favor the right brain and if she spins counterclockwise, then you supposedly favor the left brain.

Scienceline offers an excellent analysis as to why the left brain/right brain delineation may be an oversimplification: