Dare to be stupid
I was immediately skeptical when I saw this Australian site claim that you could determine what side of the brain you use more of by whether you saw the dancer above as moving clockwise or counter-clockwise. According to neurologist Steven Novella, this skepticism was completely warranted:
This news article, like many others, ignores the true source of this optical illusion and instead claims it is a quick test to see if you use more of your right brain or left brain. This is utter nonsense, but the “right-brain/left brain” thing is in the public consciousness and won’t be going away anytime soon. Sure, we have two hemispheres that operate fine independently and have different abilities, but they are massively interconnected and work together as a seamless whole (providing you have never had surgery to cut your corpus callosum).
Also, this just in: we use all of our brains not just 10%, you can balance an egg on any day of the year, and the direction of water draining in a sink is not dependent on hemisphere.