right brain left brain


This little dancer has been floating around the Internet as a test for right brain/left brain thinking. If you see her twirling clockwise you use the right side of your brain, counterclockwise and you are a lefty. I first saw it on my friend Betsy’s blog. Whether it is simply an optical illusion or an indicator of thought process is up for debate. In any case, it’s a neat little animation!

11 thoughts on “right brain left brain

  1. Hi Lilli—-I can sit and watch that girl twirl for hours. I can make her go both ways although she moves clockwise more than counter-clockwise. AND since I’m more left-brained, this is OPPOSITE… It’s a puzzlement!!!!

    Thanks for featuring this again.

  2. First it goes clockwise and then counter clockwise. I am left handed, but I am really mid brained. I turn my hand over when I right which is a classic indicator of a mid-brainer. Pappy

    • (This is in response to the sipmelr version in which the two running speeds are equal. I’ll attempt the more complex version later.) It seems to me that you can’t do better than simply running in one direction for the whole 30 minutes. Here is my attempt at proof. Call f the fraction of the loop that your friend covers in 30 minutes. That means that if you simply stand on the track (or change directions very frequently as Andrew suggests) you have a probability f of crossing paths with your friend. Now _if_ you start out running in opposite directions (which you don’t know) than you each will cover f of the track so your probability of crossing is 2f. There is a probability of bd that you start out running in opposite directions. If, however, you start out running in the same direction then the probability that you cross is zero. So the total probability that you cross if you run continuously in one direction given your ignorance of your friends direction is (1/2)2f + (1/2) 0 = f. Anytime you change directions you increase the likelihood of crossing your friend if you are initially going in the same direction, but extinguish the likelihood if you are initially going in the opposite direction. No matter when or how often you change directions, your probability of crossing will be f. So changing directions doesn’t matter and you can just keep running in the same direction.

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