Newborns already have an approach-withdrawal system: they turn toward interesting noises and away from unpleasant events. Some have a strong attraction response to events outside of themselves; others seem self-contained. Both shy and outgoing children seem to stay the same way from birth until at least their eighth birthday. (Ornstein, Robert, PhD. The Roots of the Self. NY: HarperCollins, 1995, pp 5, 39-40)