Babies do not learn in order to please us, but because it's their instinct and nature to want to find out about the world. If we praise them for everything they do, after a while they are going to start learning, doing things, just to please us, and the next step is that they are going to become worried about not pleasing us. They're going to become just as afraid of doing the wrong thing, as they might have been if they had been faced with the threat of