ABSTRACT
Imagine that you are at the beach and there is a little beachball, smaller than a volleyball, at your feet. Someone calls out, ‘Kick it!’ Imagine now kicking it really hard. Good! Now suppose the ball is at your feet again and someone calls out, ‘Pick it up and throw it to me!’ Imagine now throwing that ball. Good! Now, one last thing. You are sitting in doctor's office facing the door into the doctor's room. You hear some people talking in the room but you can't make out what they are saying. So you strain to hear. You turn your head slightly towards the door. Now, you can make out what is being said!
