Boys are better at bullshitting than girls. We know this already, but we’ve seen it again in today’s Trends in International Mathematics and Science Study findings.

The study shows that primary-aged girls are performing better in maths than they were four years ago: unlike in 2015, Year 5 boys’ average maths score was not significantly above Year 5 girls’ average maths score.

But, despite performing just as well as boys, girls lacked confidence. Boys were far more likely to say they liked maths and science - and that they were good at it - than the girls were.

This comes as no surprise to me. I’ve seen it in other studies, too. In the Programme for International Student Assessment (Pisa) study in 2015, Year 9 students were asked to name their top three choices of university. Boys were much more likely than girls to list Oxford or Cambridge, or any Russell Group university. This was true even when boys and girls went to the same school, had the same levels of prior attainment and similar family backgrounds.

Boys are just much more confident in their ambitions, and feel much more confident articulating their plans. There’s no difference in motivation for learning: girls don’t have a problem saying that they’re motivated and driven to learn. But where you have to show a more concrete ambition, they’re definitely not as confident as boys.

Timss 2019: Not just about underconfident girls

It’s not just about girls being underconfident - it’s also about boys being overconfident. They just have a better ability to bullshit.

In the past, Pisa has asked pupils to look at 16 mathematical constructs, and rank their knowledge of them, from “I have no idea what this means” to “I’m an expert”. The list of constructs included three that were fake. For example, there was “subjunctive scaling”. It sounds like it might be a real mathematical construct, but it’s actually meaningless.

This was a very low-stakes test: their teacher would never see it. But boys were far more likely to say they were experts in all the constructs - including the ones that weren’t real. They just wanted to show their expertise and their ability, even when it wasn’t actually based on any real knowledge. This was true across a number of English-speaking countries.

What are the drivers of this? There’s a lot of psychological literature around this. It’s probably a combination of societal constructs and role-modelling. There are some findings that women enjoy competition less than men, and when you display confidence, you’re putting yourself in a position of potential competition.

But it begins very early. Play shapes gender identity: demonstrations have shown that nursery workers and early-years teachers will direct children towards certain toys, depending on their sex. We’re already priming kids to make the choices we then see in secondary school and later life. That’s just crazy.

What are the consequences of it? You see, with A-level subject choice, that girls are less likely to choose Stem subjects than boys. Which then, of course, loses the subjects for them at university, and closes down certain careers.

Girls and women are doing better in lots of ways, academically, but still there’s a gender pay gap. There’s a difference in who goes into Stem subjects, which offer the highest labour-market returns.

Telling men to be less overconfident

But I’m a little bit reluctant to say that the goal here is for girls to become overconfident. Overconfidence is claiming knowledge you don’t have. I’m not sure that’s a desirable goal.

How about we tell men to be less overconfident? We need to focus on that overconfident, bullshitting aspect.

How can people in HR, in university admissions, try to look out for this sort of thing more: to differentiate between confidence and overconfidence? They could introduce a test in which there are fake concepts, as in the Pisa test - ask them about fake movies or fake artists. Introduce questions to try and suss someone out.

But, of course, by that time you’ve already got your A levels: you’ve already opted out of science or maths. So perhaps we need primary teachers to try and foster a learning environment where girls feel comfortable speaking up and displaying their knowledge. You could think of different ways for children to participate, which don’t involve answering questions in front of the whole class.

But unfortunately, yes, we need to deconstruct all of society in order to undo this trend. On one level, it’s mind-boggling to me that we don’t have more progress on this. But, on the other hand, it’s so complex and so hard to break it all down and start again.

Teachers have an important role to play here: they just need to be aware of what’s going on, and understanding how it comes about. Just having that general awareness is important.

Nikki Shure is associate professor in economics at the UCL Social Research Institute