Sit at your desk or in a chair. Lift your right foot slightly off the ground, and start moving it in a clockwise circular motion. Keep rotating it throughout the exercise.
Now take your right hand and draw a “6″ in the air in front of you, starting at the top of the six and moving down (the way they taught you to draw it in elementary school). If you’re like most people (everyone in my house who tried it, at least), your right foot will reverse direction, quite independently of your conscious volition, and start going counter-clockwise.
From my field notes:
It also works for the left foot/left hand. It does not work for right foot/left hand or vice versa. If you draw the “6″ from the inside out (so that the top of the figure is the last segment you draw), it doesn’t work – your foot will maintain its direction of motion. This leads me to think that each side of your brain has a rotation-direction module, which does not multitask, so that body movements on the same side have to rotate in the same direction.
Even moving very slowly and with great conscious effort, I was not able to make my same-side foot go contra-cyclically with my hand. As soon as I tried to move my hand the other way, my foot either changed direction or just spazzed out. I had no difficulty making the opposite side foot move contra-cyclically or in the same direction – it seems clear that the two brain halves have independent circuitry for this.
