The piecemeal emergence of language

It's been a while since I last wrote about M. She's now 16 months, and it's remarkable to see the trajectory of her early language. On the one hand, she still produces relatively few distinct words that I can recognize; on the other, her vocabulary in comprehension is quite large and she clearly understands a number of different speech acts (declaratives, imperatives, questions) and their corresponding constructions.

Some observations on production:

• She still doesn't say "mama." She does say "mamamamamama" to express need, a pattern that Clark 1973 noted is common. She definitely knows what "mama" means, and even does funny things like pointing to me and saying "dada" then pointing to her mother and opening her mouth. 
• I have nevertheless heard her make un-cued productions of "scissors," "bulldozer," and "motorcycle" (though not with great reliability). Motorcycle translated to something like "dodo SY-ku" – a kind of indistinct prosodic foot and then a second heavily stressed foot. Her production vocabulary is extremely idiosyncratic compared with her comprehension, precisely the pattern identified by Mayor & Plunkett (2014) in a very cool recent paper. 
• "BA ba" (repeated over and over again) seems to mean "let's sing a song" – or especially, let's watch inane internet children's song videos. We don't do this last all that often, but it has made an outsize impression on her, perhaps because she's seen so little TV in her short life. This is also the first time that she's taken to repeating a single word / label over and over again, so as to emphasize the point. 

And on comprehension:

• Our life got vastly better when M learned how to say "yes" to yes/no questions. For about a month now, we've been able to say things like "would you like to go outside?" and she will reply "da!" (she is Russian, apparently). "Da" has very recently morphed into "yah" but it's very clearly a strong affirmative. M will occasionally turn her head away and wrinkle her nose if she doesn't like the suggestion. This response feels a lot like a generalization of her I don't want to eat that bite face. 
• Other types of questions have been slower. Maybe unsurprisingly, "or" is still not a success – she either stays silent or responds to the second option, even if she knows how to produce a word for one or both options. "Where" questions have been emerging in the last week or so. This morning, M was very clear in directing me when I asked her "where should we go?" "What's this" is uneven – occasionally I'll get a "ba" or "da" (ball/dog) type production. And "what do you want" has only gotten a successful production once or twice (bottle, I think). 
• M understands and responds to simple imperatives just fine: "take the cup to baby" gets a positive response, though her accuracy on less plausible sentences is low.
• Explanations seem to hold a lot of water with her. I don't think she understands the explanation at all, but if we need to give something to someone, or leave something behind that she's holding, we ask her and then explain. For example, telling her why we can't bring her favorite highlighter pen in the car with us seems to convince her to put it down. What's going through her mind here? Maybe just our seriousness about the idea – something like wow, they used a lot of words, they must really mean it? 
• She is remarkably good at negation (at least when she wants to be). A few days ago we were headed out the door to the playground, and M tried to drag a big stroller blanket out the door.  I said "We're not going to bring our blanket outside." She headed back over to the stroller, and dropped the blanket. Of course, then she headed back towards the door, turned back, and grabbed a smaller blanket. There was a lot of contextual support to this sequence, but understanding my sentence still took some substantial sophistication. The negation "we're not" is embedded in the sentence, and wasn't supported by too much in the way of prosody. This success was very striking to me, given the failures of much older toddlers to understand more decontextualized negations in some research that Ann Nordmeyer and I have been doing. 

Overall, I am still struck by how hard production is for M, compared with comprehension. A new word, say "playground" might start as something resembling "PAI-go" but merge back into "BA-ba" by the end of a few repetitions. M has never been a big babbler, and so I suspect that she is slow to produce language because the skills of production are simply not as well-practiced. There are some kids who babble up a storm, and I imagine all of the motor routines are much easier for them In contrast, M just doesn't have the sounds of language in her mouth yet.