View Photo Gallery: From the American Red Cross to the Supreme Court, more and more institutions of power in the nation’s capital are seeing women take the lead.

There are more explanations for the dearth of women in leadership roles than there are digits on a CEO’s paycheck. Boards of directors are biased, apparently. Women who take time off to have children risk never catching up. Oh, and my favorite: We supposedly don’t negotiate very well.

Add to that ever-expanding list of reasons a new one: Men are simply more overconfident than women. In a recently published study in the Journal of Economic Behavior & Organization, professors from Columbia Business School, Northwestern University, the University of Chicago and the Autonomous University of Barcelona found that when asked about their past performance, men were more likely to overstate their results. The researchers called this “honest” or “natural” overconfidence something that may explain more leadership gaps between men and women than just overt bias in the selection process.

Here’s why. The researchers gave a group of MBA students a math test, and men and women performed about the same. But a year later, they asked the students how well they’d performed. While most of the students recalled that they’d performed better than they did, the women only inflated their scores about 15 percent. The men inflated theirs, consistently, by twice as much.

That alone, of course, would not explain why overconfidence might lead to there being more men in leadership than women. So the researchers performed another study. In it, they put the students into groups, and asked each to choose a leader to represent them in further competitions; the highest-scoring would be given a cash prize for their teams. Therefore, it was logical that the teams would choose someone to represent them who said they performed very well in the past. In addition, the leaders of some of the groups were given their own cash incentive, making them more apt to lie about their past performance, since those representatives stood to gain even if the group lost.

The results? Men and women lied about the same amount, and when they were motivated to lie—that is, when they had cash dangled before them—they lied more, whatever their gender. But even if there appeared to be little gender difference in the frequency of fibbing, there was one in the degree to which they did it. Men exaggerated their past performance more than women. And as a result, women were selected a third less often to be leaders of the groups.

As anyone who reads this blog knows, I’m often skeptical about such studies. Applying the results of an experiment that involves students remembering their scores on a math test to the cultural vagaries and nuances of gender politics in the boardroom feels just a wee bit like an artificial construct. Not to mention the common sense involved: I am sure there are plenty of women reading this who are, well, not surprised at the researchers’ findings.

Women’s under-representation in top jobs is a complex issue involving decades of history, societal issues and innate realities that can’t be simply explained by seeing how MBA students react under the microscope. Still, it’s worth keeping these results in mind when selecting leaders for top jobs.

So what to do? After all, it’s not like the candidates can correct for it themselves: “It’s not just a matter of telling men not to lie,” Columbia Business School Professor Ernesto Reuben said in a release about the study. “They honestly believe their performance is 30 percent better than it really is. Similarly, it’s not as if you can simply tell women they should inflate their own sense of overconfidence to be on par with that of men.”

As a result, company leaders and recruiters, the researchers say, should consider whether or not their male candidates are exaggerating their past performance, a natural tendency that could prompt them to overlook female candidates. Prod past references more. Demand details on past achievements. And mentor women to tout their accomplishments more. Doing so may be just one thing to help close the gap between men and women at the top, but it could very well count.

More from On Leadership:

Is it a bad sign if boards are ‘looking for a woman’?

How to be a great boss

Mr. Schmidt goes to Washington

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