Here's an interesting twist on the left-brain/right-brain perception test. Depending on which way you see the dancer turning purportedly indicates whether your left brain or right brain is dominant.
I started out seeing her turning clockwise, but when I looked away to read the text and then looked back, she was turning counterclockwise. I can't make her change direction when I'm looking at her, but if I look away and then look back, she changes.