@mismi,
I'm agreeing with Mismi's and Roger's views - haven't reread all the thread.
Patently I think that attention to a baby and toddler with eye contact, touching, talking to or singing to, holding, pointing at things and saying the names, showing words that match the names, is important, and probably gets tricky with a parent who isn't very engaged with what is around him or her, or has trouble hearing or speaking - thus sign language, a whole other subject, it's so great that was developed.
I just know anecdotal stuff, mixed with long time observations which are just mine. On the latter, I think raising a child with curiosity is key, best one can, and there are many versions of curiosity.
On the anecdotes, my mother often (enough) told me I didn't speak until I was four. At this point, I think she meant a full sentence, and that was "New car, Dad". And that was in post war 1945, when I turned four. But I have childhood memories of an oil cloth "book" to read and slobber over, and some blocks, and a rag doll named Daisie, and so on. I was an only child in a family that moved a lot, and went to kindergarten and 1st grade as shy as a post, having only rarely been around other children (no day cares). But I had love, and did fine in school. And now you can't shut me up, eh?
A cousin was the worst reader and speller for miles around, flunked latin twice, went through college using a tape recorder. She was dyslexic, but that wasn't all that known about back then. She went on in schooling and spent her work life as a CPA for the US gov. Very able and good human. Sixty years later she reads for pleasure. I'm sure she was behind in reading in third grade.
I highly doubt governors make prison building decisions on that basis.