In the 1980s, a researcher looking at how boys and girls thought about their own intelligence arrived at a theory known as the “mindset theory,” and within that, the “bright girl effect.” The theory suggested that kids have different attitudes about what they can accomplish: Some have a “growth mindset,” believing that even when they are struggling with something, they can eventually succeed.

Other kids have a “fixed mindset” — when they are having trouble with something, they believe it's because they aren't capable enough — that their intelligence is fixed and not changeable over time.

Children who are praised for their smarts tend to give up much faster on challenging tasks than those who are praised for their hard work.

Because girls mature faster than boys, the theory goes, they are more likely to be labeled as “bright,” so they are more likely believe their intelligence exists apart from hard work. This is a problem, the authors of a recent study believe, as it may be that how we think of our intellectual abilities is largely a product of the input from what those around us say.

A Case Western Reserve University study set out to test whether adult women were more likely than men to have a fixed mindset, since these tests have so far only been done in kids and teens.

Apparently these bright girl mindsets don’t last. The researchers had 400 women fill out the same questionnaires that were given to children and adolescents as part of the development of the mindset theory. They rated how much they agreed with statements such as, “You can always substantially change how intelligent you are,” and “No matter who you are, you can significantly change your level of intelligence.”

The same patterns were not present in adult women. “These studies help fill in gaps in the mindset research,” said study author, Brooke Macnamara, in a statement. “Some past research has suggested a ‘bright girl effect’ — gender differences among children. However, a ‘bright woman effect’ — gender differences among adults — seemed to be an untested assumption. Across our studies, there were no consistent relationships among intelligence, mindset and gender. Our research did not support the idea of a ‘bright woman effect.’”

In other words, the women became aware that they could become better at things. This is a good thing: Believing that one’s intelligence is unchangeable is not a particularly healthy belief, and can be quite limiting.

Other research has found that stressing the importance of hard work helps kids develop a lot more grit than stressing intelligence does. Children who are praised for their smarts tend to give up much faster on challenging tasks than those who are praised for their hard work. So regardless of how smart you think you are, believing your intelligence is predetermined is harmful and likely to work against you.

It’s not clear why the bright girl effect tends to fade over time. More research will be needed to understand how it changes with age, and affects school and career choices. In the meantime, if you have kids, let them know that intelligence is changeable — and that hard work matters.

The study is published in the journal Intelligence.