DAVID GREENE, HOST:
In elementary schools in the United States, educators have seen differences in test scores among girls and boys. On average, girls perform better. This is not the case with every single child, but there are broad differences. There's been intense debate about what might cause these differences. Studies have looked at whether these differences are innate, or shaped by how we raise kids.
NPR science correspondent Shankar Vedantam joins us regularly to discuss interesting social science findings. And he's found some new research that suggests the way parents interact with very young children might be playing a role here. Shankar, welcome back to the program.
SHANKAR VEDANTAM, BYLINE: Hi, David.
GREENE: So Shankar, it feels like we're talking about research here that touches on a lot of fields - education, psychology.
VEDANTAM: Yeah, I mean, there has been a ton of research in all of those fields, David. Interestingly, this piece of research comes from a pair of economists. Michael Baker, at the University of Toronto, and Kevin Milligan, at the University of British Columbia, they recently mined survey research done in three completely different countries - the United States, Canada and Britain. They looked at how parents reported interacting with very young children; these are preschool children in all these countries. And they found that when it came to some specific activities, there was an interesting disparity in how much time parents spend with boys, and how much time they spent with girls.
MICHAEL BAKER: When we looked at specific activities - what we call teaching activities; so this would be, how often do you read with your child or, how often do you teach them the alphabet or numbers - systematically, parents spent more time doing these activities with girls.
GREENE: I guess one important question, though, is, are parents spending the same amount of time with boys and girls? That seems like something important to sort out.
VEDANTAM: Yeah. That's a great question, David. Interestingly, Baker found that they do, indeed, spend the same amount of time with boys and girls. So they're not necessarily reporting that they're spending more time with girls overall. It's just when it comes to these specific activities, they seem to be spending more time with girls than boys.
GREENE: OK. So do we think that there's a link there to girls performing better on tests in elementary school?
VEDANTAM: So that's the $64 million question. And remember, these are economists. So what they're saying is look, we had these two, separate findings. First, we've known from previous research that there are these test-score differences in elementary school. And second, we're finding that there are these different investments from parents, when it comes to these cognitive activities.
Baker told me that he built a model that asked, what would happen to the test scores if we were to eliminate these disparities in parental investment? And remember, he's not actually changing what parents are doing in real life. He's building a statistical model that tries to control for these disparities. And he finds that the differences in parental investment might explain as much as a third of the test-score disparities, which is really quite a lot.
BAKER: If you look at the boy-girl difference in the test scores at age 4 and 5; and then you look at them again but this time are counting for the differences in how their parents read to them or taught them letters and numbers, the boy-girl difference in the test scores shrinks.
VEDANTAM: So Baker has multiple theories. And one of the theories he has - I mean, he's an economist, and so one of the things that economists do is, they say, what are the incentives for people to do different things - you know - and what are the costs involved? And when economists talk about costs, they're not necessarily talking about cash. They're also talking about the amount of effort that's involved. And Baker is asking, is it possible that there are different costs in investing these cognitive activities in boys versus girls, and could that be explaining the disparities?
BAKER: The costs of providing these inputs are different for boys and girls. So for example, it is just more costly to provide a unit of reading to a boy than to a girl because the boy doesn't sit still - you know, doesn't pay attention, these sorts of things.
VEDANTAM: So it's a feedback interaction between the parent and the child and - you know, that's being shaped by all kinds of things. But what he's suggesting is, it's possible that parents are getting signals from their children about what they're willing to do; and then that shapes the parents' behavior, and then the parents' behavior, in turn, shapes the child's behavior; and then you have these loops.
GREENE: So Shankar, I have to say, this is the kind of subject matter that some parents will probably have reactions to. I know this is just one study. Do these researchers, though, have any advice for parents?
VEDANTAM: Yeah. That's a tricky one, David. And I asked Baker about this, and he told me that in general, as a parent himself, he tries not to give advice to other parents.
GREENE: That's probably a safer position to stand on.
VEDANTAM: Yeah. He did tell me, though, that he has a boy and girl himself, and his girl showed greater interest in reading and math at a young age. But his response, and his wife's response, was to tailor far more attention to the boy as a result; and try and counter, perhaps, with this natural inclination may have been.
GREENE: Interesting - something for parents to think about. Shankar, thanks so much, as always.
VEDANTAM: Thanks, David.
GREENE: That's Shankar Verdantam, who regularly joins us to talk about interesting social science research. You can follow him on Twitter @Hidden Brain. And while you're at it, you can follow this program @NPRgreene, @NPRinskeep and @MORNING EDITION.