A parent's simple act of being responsive is a form of praise. This will typically include looking and smiling, though there's little point in trying to fake such things if they don't come naturally.

Children who don't have responsive parents will tend to 'misbehave' until the parents become more responsive. I put 'misbehave' in quotes because although the form of the behaviour is bad, children are entitled to have responsive parents, and they know no other means of obtaining them

I think I know what you mean about words: children learn their moral ideas from parental behavior rather than from what their parents explicitly tell them to do.

But note that parental behavior includes words. So the principle is consistent with giving verbal descriptions of what a child is doing as he is doing it, or just after, or asking a question about it if you have one.

(I mean a real question, which is only rarely about feelings. I add this because all too many adult-child interactions are peppered with fake questions like 'Are you a good boy?' etc)

Verbal descriptions are helpful especially when, as we are discussing, something cool has happened, since there the child is operating at the edge of his ability and understanding, which is usually inexplicit in his mind. A verbal understanding helps to consolidate the achievement and also to introduce creative variations