But I think geofizz's point is regarding your original claim, that "Talking is hard. Why talk when there's signing? The primary motivation for kids to work on their linguistics is the need to be understood. She doesn't have that need, and so, she's not working on it. It's not a priority."
I think this is an important point. I wonder, though, if this will change as she gets older and is exposed to more people who don't understand sign language. It would be interesting to know how many of the people she is with everyday are fluent in sign, rendering verbal speech unnecessary.
This is such an interesting topic... the need to communicate Vs. having learned vocabulary. Neither of my (non-verbal until 24 months) kids knew any sign, but I can't even guess as to what DD's vocab was. I could ask for anything and she'd point to it. I lost track of how many words she knew. It didn't seem to bother her, though, that she couldn't speak or sign. Maybe that's because I hovered and anticipated her needs so she didn't have to verbalize them?
Then there's my DS... when he started talking it was within a day or two of his 2nd birthday. He went from being completely non-verbal to handing me alphabet blocks and naming them all (he knew all 26). He just... decided to start talking, out of nowhere. Boom, just like that. I'm going to start talking by telling mommy what these letters are called.
How is that a need to be understood? Or is that a form of hyperlexia? (i.e. is that a typical child, a spectrum child, a gifted child, or simply a quirky one?) He was looking at me, making excellent eye contact, and talking to me. But he wasn't saying "mama, up" or "juice please" or whatever. Instead it was "cee! dee! efff! emmm!" etc etc as he correctly handed me the corresponding block for each. Within weeks, just like DD after her late start, DS was also speaking in sentences. It's as if once they started, the flood gates just opened.
Islandofapples - when your DD signs, is she engaging with you or is she just labeling objects? Is she engaged and connected or is she encyclopedic and methodical?
They're so interestingly unique that it can be hard to identify warning signs. There's no harm in pursuing professional help though - that way your bases are covered.
