The A League of Their Own and Thelma & Louise star has been a vocal advocate of issues concerning pay inequality and roles for women in Hollywood for several years, and in 2007, she launched the Geena Davis Institute on Gender in Media to help increase the female presence onscreen and reduce stereotypes surrounding women in the media, and last year (15), she created the Bentonville Film Festival in Arkansas in a bid to highlight films featuring minorities and women.

"I have been an advocate for women for most of my adult life... and the Bentonville Film Festival is a critical component of how we can directly impact the quantity and quality of females and minorities onscreen and behind-the scenes," she previously said.

She is now developing a documentary on the subject.

"I've been encouraged by my peers speaking out on gender disparity in recent years, but we still are not seeing the actual number change," she tells Variety. "There's been no real improvement in the number of female roles since 1946 and there's still a dearth of female directors."

Filmmaker Tom Donahue will direct the film, which will feature researchers from Geena's institute and her actor peers talking about the issue.

Last year (15), Geena praised the likes of Jennifer Lawrence, Jessica Chastain and Sienna Miller for making a stand for equal pay.

"It's great that my colleagues are speaking out about this and it's a hot topic and there's so many articles about it and attention on it," Davis told U.S. news show Access Hollywood Live.

"I think what's gonna help a lot is this attention and also what Bradley Cooper did by announcing he's gonna tell his female co-stars what he earns so they can negotiate with that. We need other guys doing that."