I can't understand how come "buttons" are associated with people and their behavior. How did these idioms come to be?
Edit: I feel I am not being clear with the question. What I intend to understand is the relation of a person's pysch and buttons. As it is unusual to talk of hurting a machine's feeling, likewise it should be unusual to speak of somebody's button as well. This being my point, how did the metaphorical idiom originate(and considered meaningful)?