We shall study separately gesture, action, and volition. By gesture we mean a motion of the body (or of parts of it) that expresses a special psychological state of the individual. By action we mean a purposeful or meaningful behavior, even if the purpose or meaning is not known to the subject. Volition is the process of choosing and of initiating, continuing, actualizing, interrupting, or terminating the chosen action. When we study volition, we refer to the process of choosing and putting into effect the action.