Stick out both index fingers as if you are pointing at something. Slowly begin rotating them in the same direction. Do this slowly at first and now gradually increase the speed. Keep going faster and faster. You will note that they now begin to move in opposite directions. It is difficult to keep them moving in the same direction. Trippy!
My dominant hand, right index finger, was the one that set the pace and the direction of the movement. My left index finger could not keep up and seemed confused moving back and forth, very choppy and uncoordinated, instead of in a circular motion.
But when I tried rotating the fingers in opposite directions to begin with, my fingers had no problem. No matter how fast you go, your fingers will continue to move in opposite directions with seemingly no effort on your part. This feels like the natural way your fingers should move.
With great practice and concentration you can overcome this particular quirk and make them move in the same direction. However, for researchers and mind trippers it is an interesting footnote to understand that we react naturally in ways that are hardwired into our brain. Our brain is wired in very particular ways. There is so much research on the brain, but a couple of good articles about the brain hand connection are the following: