There's a good TED talk where they go into the differences in language processing in a child of 12 months vs 15 months. Infants and very young children are doing so fucking much to deal with learning the basic rules of the real world, and how to process human language. (One of the notable things is that American children exposed to a real human speaking Chinese to them on a regular basis were able to differentiate the sounds of Chinese as well as Chinese kids; those in control groups exposed to video of people speaking Chinese didn't fare any better than regular American kids.)

I feel like the awesome and mysterious stuff going on in the child's mind at that age in order to come to grips with the real world, in its awesome complexity, is too important to be displaced by addictive recreational activities that can just as well come later. I don't want them to become masters of the small and limited worlds in which games exist, at the expense of a diminished mastery of the intricacies and awesome breadth of the actual world we live in.

https://www.ted.com/talks/patricia_kuhl_the_linguistic_geniu...