An interesting study that brings into question a lot of assumptions and demands more, and larger, studies. There's a lot of differences between conversation types depending on family and culture. Both conversations with kids and around them.
sciencenews.org/article/word-g…
sciencenews.org/article/word-g…
It's silly to assume that a well off family from academia has the same household conversations as a well off family from banking, much less if one of those families is Latinx and another is Korean and a third is White.
If you then add in class differences... talking about landscaping around kids could be very different than talking about the stock market. OR it could be not different at all. Kids are fascinated by stuff. We'd need more studies with larger groups that looked at content.
I would suspect that more than a word gap there's a word separation. That the circles of the venn diagram don't overlap as much as you might expect. That word gap could then translate to a concept/reference gap when it comes to things like school and testing.
An anecdote from my own childhood. I was raised a-religious at first, with a passing understanding of the basics of the big Christian holidays. As I entered school age, my parents realized that tests often referred to Biblical stories, assuming they were common knowledge.
Because of their backgrounds, they saw the potential pitfall there and got me some books and helped me get familiar with those stories, with Jewish stories, and Greek ones (which then spawned a love of mythology in general).
Without that added background, I would have tested lower on many standardized tests over the years, not because I had a word gap, but because of a concept gap caused by a subject we simply didn't talk about. We talked about accretion disks (because I was fascinated by them).
