Researchers surveyed over 1,800 academics from 30 different disciplines and found that the value of presumed brilliance (a spark of genius in the field, if you will) was a better predictor for under-representation of women in that field than any other hypothesis tested.
In addition to giving weight to their own hypothesis, the researchers were able to knock out some popular explanations for gender gaps by comparison: That women shy away from fields that require more hours of work, that women don't make the cut in fields where only the top percentile of students are successful, and that women are less likely to choose fields that require analytical thinking than men are.
And the same held true when researchers applied the test to African-American representation, indicating that this bias for "brilliance" may keep those individuals out of such fields as well.
In the fields that valued brilliance, researchers were also more likely to agree that women and African Americans were less suited to the work.
These two fields are a great example of how complex gender inequality in academia is. It would be simple to say that women favor the humanities and men favor the sciences, but that's not true. Some scientific fields, like molecular biology and neuroscience, have achieved gender parity. And some fields in the social sciences and humanities, like economics and philosophy, favor men heavily.
Cimpian and Leslie frequently discussed issues of gender in their respective fields. Psychology seemed to embrace women, with female researchers earning 70 percent of all PhDs in the field. But in philosophy, less than 35 percent of such degrees went to women.
Marked differences in the cultures of their disciplines came up a lot, too. Philosophy praised innate brilliance -- in the 1980s, people spoke of "the beam" of enlightenment that had been bestowed upon those gifted in philosophy -- but psychology emphasized hard work and study.
"At some point we were at a conference and these two ideas finally came together," Cimpian said. What if fields that idolized brilliance were favoring men and scaring women away as a result? "After we mustered up the courage to actually do the study, we tested this idea empirically. The magnitude and strength of the relationship came as a surprise."
Their findings don't suggest that women are less brilliant than men, Cimpian and Leslie said. When they tested to see whether how elite a field is predicted female success in it, the results were no better than chance. And there's no strong research to support the idea that men are more likely to be geniuses than women are. Rather, the findings suggest that the presumed differences between men and women could be interacting with presumptions about success in certain fields.
If we all grow up thinking that men can be brilliant by nature -- think haphazard genius like Sherlock Holmes and Dr. House, or the main character in "Good Will Hunting" -- but women who are successful need to work hard, like Hermione Granger -- women are less likely to feel confident entering the fields that you're supposed to just have some sort of knack for. And the gatekeepers of those fields will unconsciously keep them at bay if they try.
"Any group that's stereotyped to lack a trait that a field values is going to be underrepresented in that field," Cimpian said.
Luigi Zingales, a professor at The University of Chicago Booth School of Business and author of a study on gender stereotypes in science academia, said he wasn't surprised by the results. He wasn't convinced that the study showed this "raw talent" bias as a cause for the gender gap, however.
"The hypothesis the authors advance might well be true, but it is observationally equivalent to the alternative that these fields are more competitive and that women shy away from competition," Zingales said. Further study could show this more definitively. But either way, he said, the results showed "a desperate need for education on the issue [of gender bias] at all levels."
In future studies, Cimpian and Leslie will try to see how far back this bias goes. Do girls in kindergarten think they're less likely to be inherently talented in math than boys are? They hope answering questions like this will help educators design meaningful interventions.
For now, they have one simple recommendation based on their study: Professors should be honest about how hard they've had to work.
"I was very lucky to have some incredible mentors and role models who were never afraid to speak to me about how much they struggled to get where they were," Leslie said. "It's not just a matter of rolling out of bed and being gifted, they told me, it's a matter of putting in time and energy. If not for those mentors, I wouldn't be in philosophy."
Someone who isn't performing at the level they wish to be at in math or philosophy can always improve, Leslie said, and emphasizing born talent over hard work may end up preventing women -- even ones who carry that very innate talent inside them -- from diving in.
"In an ideal world you'd intervene on both sides at the same time, changing these gender stereotypes and changing the culture of the academic fields," Cimpian said. "But practically speaking, we know that stereotypes are hard to change."