Can you do this?
Here’s the explanation from WonderHowTo:
It took quite a bit of digging to trace this trick back to Professor [Hermann] Haken and the science of Synergetics. This science deals with the ways that complex systems work. In a complex system such as your brain and nervous system, there are many different signals moving back and forth. Some of these signals are treated with more importance than others. Some of the signals also become coupled, with one signal guiding the other. That is what is happening with your foot and hand. Your hand movement couples with your foot movement, but your hand movement is treated with more importance, so your foot changes direction.
Even more interesting is that you don’t actually have to move your hand. Try the experiment again, but this time just think about drawing the number 6 in the air. Your foot will still reverse. The pattern of your thoughts still couples with the movement of your foot.
~E