Rich: Being the parent of an almost-3-year-old, I’m currently learning the joys of early speech myself these days (bilingual speech at that, which is a whole ‘nuther kettle of fish).
The field concerned is called “Language Acquisition”, and aparrently Noam Chomsky is the field’s main mover and shaker. The interesting thing about children’s speach is that instinctively, kids figure out the important words in a sentence – and not just the important words, but the important parts of them. So suffixes, prefixes, conjunctions, and helper versbs all get left behind and all you get are action verbs, nouns and names. “Thomas go plouf” is a particular favourite of ours right now that we’re trying to talk him out of (it’s bath related).