I've always believed that it is wise to treat children with the same respect you give adults, to assume they understand everything you say from day one, and to respond to them quickly and accurately. I've always believed they were trying to communicate from day one. And I don't believe in letting kids cry _anything_ out alone. From nursery to bedtime, every time they try to communicate, I try to respond, and to respond as though they are people with minds, emotions, thoughts, and memories.
Turns out, science says my way (which is, by the way, extremely unpopular because it is time-consuming and requires you to negotiate with a child, since their needs and thoughts are equally important to yours) makes smarter kids!