[vqdnpfqz] Rock paper scissors machine

I read that brain sensors can detect your thought before you consciously notice you're having that thought.

Create a machine which, after you attach electrodes to your skull, will beat you at Rock-Paper-Scissors.  Create a mechanical contraption to make it plainly obvious that the machine is choosing and committing to its throw slightly before you display yours, so not cheating: perhaps a ball falling through an opaque tube.