Originally Posted by JonahSinick
The 1996 study Self-Efficacy Beliefs and Mathematical Problem-Solving of Gifted Students found that

Although most students were overconfident about their capabilities, gifted students had more accurate self-perceptions and gifted girls were biased toward underconfidence.

Facebook chief operating officer Sheryl Sandberg discusses high potential women being underconfident in her book Lean In.

I've had many gifted female students and classmates/colleagues who have struggled with intellectual insecurity.
Some who think that underconfidence in gifted girls is a serious problem believe that it discourages them from majoring in STEM. The article below finds that women are more strongly discouraged than men from majoring in economics when they don't get an A in the introductory course. I think I have read about a similar pattern in STEM. But majoring in something you are good at does make sense. It's not clear that men are being more rational than women in choosing whether to major in economics or STEM.

Women should embrace the Bís in college to make more later
by Catherine Rampell
Washington Post
March 10, 2014