Subtitle: "How Children Learn and Unlearn the Languages of the World". It's a book by a linguist, about linguistics, and the author cautions in the introduction that it is not intended specifically for parents of small children. Nonetheless, I think it may have helped me to understand why Juliet constantly referred to the cat as her dad when she was little.
The good thing about linguists who study how language is acquired, is they get to play with puppets a lot, and they get to confuse small children for a living. There are serious linguistic topics being investigated, but the real fun of the book is learning things like:
1) small children will talk to a puppet, when they won't talk to you
2) small children who won't answer your question because they're too shy, will gleefully shout out when Kermit the Frog gets the answer to that same question wrong, because it's always fun to point out when others are wrong
3) small children in a laboratory environment have a curious tendency to want to say "yes" to all questions, even if the self-same child is in the stage where they like to say "no" everywhere else. The author laments that even the researchers who are parents have not found a way to replicate this behavior outside the lab
4) small children who make grammatical errors themselves, will still often notice (and comment with disapproval) when you make the exact same errors back to them.
5) in some areas of Papua New Guinea, adults make a point of never talking to children too small to talk back. They talk in their presence all the time, of course, but they don't talk to them. These children learn how to talk just as early as any other group of people.
6) "motherese", the style of speech where adults use a softer, higher voice and simplify the sounds of words, does not appear to do anything to either speed up, or slow down, when children learn to speak.
7) in case you needed anyone to tell you this: kids understand what you're saying, way before they can say it themselves.
If you can deal with the too-frequent references to the Boston Red Sox, this is a fun read. The gist of it is that children start off with an instinct for all grammars, rather than none, and progressively "unlearn" all but the one that becomes their native language. In a similar fashion, they can distinguish all possible human language sounds, which means they are easily confused about which ones matter, and gradually learn to ignore the distinctions that don't matter for their native language (for example, Koreans learning to ignore the difference between "l" and "r"). It makes sense, even if it doesn't really change anything about how I will teach Juliet to talk. But if you've ever wondered "why is this so hard?" when learning a foreign language's grammar, it's fun to read a quick and light overview of what we know about how we learned the first one.
Oh, and about the fact that Juliet kept saying Julian (our male cat) was her dad:
Ok, actually she referred to the cat as "dada". I always responded to this by saying, "no, I'M 'dada', you are not actually a cat." Apparently this kind of thing is a normal error, and she was actually getting "cat" about 50% correct. The first sound has three distinct tricks involved: tongue near the back of the mouth, explosive burst of air, and not voiced (if it were voiced, it would be "g" instead of "k"). She was getting the explosive part right, so that's 1 for 3.
The "a" sound was right.
The "t" sound should be tongue near the front of the mouth, explosive burst of air, not voiced. She was getting the first two correct, but she was making the sound voiced, so it was "d" instead of "t". So 2 out of 3.
Multiply that out and add it up, and she's getting it half-right. Ok, there was an extra "a" at the end, but close enough. At least, she didn't actually think Cassandra cheated on me with Julian. So far as I know.