Suppose that because of epilepsy you have had the connection severed between your two brain hemispheres so that one side does not communicate with the other. In an experiment, somebody shows you a card that says "Walk." So you walk. When asked why you did it, you say, "To get a drink of water." In fact you only did it because you saw the card. You made up the explanation after the fact. This couldn't happen to you, right? Wrong.