Amy Hinsley has spent years studying wildlife conservation and she's become an expert in her field. But whenever she attended a scientific conference, she felt reluctant to put up her hand and ask a question.
"I would wonder whether my question was good enough or I would hesitate to ask a question," said Dr. Hinsley, a 33-year-old research fellow at the University of Oxford who studies the black market for endangered plants and animals.
A few years ago, she raised her insecurities with fellow researcher Alison Johnston, a statistician in the department of zoology at Cambridge University, and found she'd had similar experiences.
"We were just talking about how we noticed that we go to lots of meetings and talks and conferences, and we were noticing that more men were asking questions than women," said Dr. Hinsley.
Their discussion led them to conducting an unusual study at a major conference in 2015, the International Congress for Conservation Biology, in France.
Together with a team of volunteers, the researchers counted the number of men and women asking questions at 31 workshops during the four-day conference.
They analyzed 270 questions asked during the sessions which were attended by 1,487 women and 1,116 men.
In total, they found that men asked 80 per cent more questions. And they discovered that age didn't matter since the same pattern emerged among older and younger attendees.
They also found no bias among the workshop chairs in terms of which questioners were selected.
Dr. Hinsley said she wasn't surprised at the overall conclusion that men asked more questions but added: "I was surprised by how many more questions. I mean 80 per cent more, that's almost twice as many questions as women were asking."
The study, released on Monday, has raised a host of issues for women in science that could be holding many of them back, regardless of their age. Other studies have shown that men are more likely to speak at conferences, which gives them a higher reputation than female peers.
And if women already feel they have lower status due to bias throughout their career, they may be less likely to participate in public discussions, setting them back farther.
"This negative feedback loop can affect women and men, but the evidence in this study suggests that women are affected more," the co-authors concluded.
The study also raised the possibility that men use questions as a way of competing with others to showcase their knowledge.
And it added that the "act of asking a question is linked to higher levels of self-confidence, with lower confidence linked to a desire for self-preservation that makes question asking less likely.
"In many cases, current gender differences in behaviour are likely to be a long-term response to wider experiences of inequality that women may have faced. Therefore, our findings may reflect a lower level of self-confidence amongst female scientists, who are likely to have faced academic and professional barriers based on their gender that men have not," the study noted.
While the study looked at just one gathering, another study from an astronomy conference came to similar findings.
Research done elsewhere has also shown that women ask fewer questions at university lectures and in school classrooms. And early education studies have concluded that while boys and girls participate equally in school early on, by the age of 9 girls start asking fewer questions than boys.
"We currently don't know the reason behind this and I think that's the biggest conclusion that we can draw from this; that we've shown that this is happening at the professional level," said Dr. Hinsley.
"I think the next steps need to be to find out why this is happening and to do some further work."
One solution is for questions to be posed via social media instead of a show of hands. Studies have shown that women participate more than men when questions are asked online instead of face-to-face.
"We can work to address the symptom, which is the lack of questions from women in conferences," Dr. Hinsley said. "We can start getting chairs to [select] women to ask questions, we can have questions via a different format, maybe via Twitter instead. But that's not addressing the root cause of this and I think what we need to do is look at the underlying causes and address the wider issue of inequality in STEM [science, technology, engineering and mathematics] subjects."