Maggie Gyllenhaal told a Busan International Film Festival press conference on Wednesday that the best directors she worked with as an actress, who were usually also the most successful, understood the value of drawing on the minds of the people around them.

“It was the people who were very scared… or just not very smart, who tried to squash other people’s voices,” Gyllenhaal said.

Gyllenhaal is in Busan with “Flesh Impact,” a short film she wrote and directed in which Ellen Burstyn plays Marilyn Monroe at 100 and Dakota Johnson plays the star in her youth. When she made her feature directing debut, “The Lost Daughter,” her main concern was that everyone on set, from the actors to the cinematographer, production designer and gaffer, felt free to contribute.

“The truth is… it is ultimately up to me as the director. I have the power, so there’s no reason to squash anyone else’s voice,” she said. “I mean, it’s just so obvious that the movie that I will make that includes all the minds of the people on my crew, at least as things I can draw from, is going to be exponentially better than the movie I can make trying to recreate something I imagined all alone by myself in my room.”

“Flesh Impact” began as a commission from Genesis, the luxury car brand and a longtime Busan sponsor, to mark what would have been Monroe’s 100th birthday in June. Gyllenhaal said she knew the star mostly through her image as a screen icon, and took a week to decide whether she had anything to say about her. She spent it reading about Monroe and watching her films.

“I don’t think that when Genesis came to me and asked for a film about Marilyn Monroe to celebrate what would have been her 100th birthday that they imagined she would actually be 100 years old in the movie,” Gyllenhaal said. “I thought, ‘Okay, I have this idea. They’re never going to go for it.'”

Genesis approved the pitch, and Gyllenhaal finished the script within a weekend. The film, which also features Peter Sarsgaard and Sepideh Moafi, world premiered out of competition at the Venice Film Festival. Gyllenhaal said that as much as the film celebrates Monroe, “it is also 100% a celebration and an honoring of Ellen Burstyn and her incredible career, and Dakota Johnson and her incredible career.”

Gyllenhaal said the move from acting to producing and then to writing and directing felt natural. When she was young, so few women were directing that acting seemed the obvious outlet for a woman who loved movies and wanted to tell stories.

“It felt satisfying and exciting for a long time, and then I think I hit the edge of what I was able to do as an actress,” she said.

Her move into writing and directing began eight years ago with “The Lost Daughter,” and she said she has felt more at ease and more inspired behind the camera ever since.

Film runs in the family. Gyllenhaal’s father, Stephen Gyllenhaal, is a director and her mother, Naomi Foner, a screenwriter. Growing up, the family went to the movies almost every Friday night, Gyllenhaal said.

“My mom directed her first film as a grandmother. I think she might be the only person to have directed her first film as a grandmother,” Gyllenhaal said, calling her mother “probably the best note-giver that I have.” Her brother Jake Gyllenhaal, who appeared in “The Bride,” is a close friend whose different taste she called a gift.

Gyllenhaal said she has begun writing two “kind of budding ideas” and is “in that very exciting place where I’m kind of like, ‘What is this going to ultimately be about, you know?'” Variety reported in June that she will direct and produce an adaptation of Rachel Kushner’s novel “Creation Lake” for Warner Bros., which also backed “The Bride.”

On the subject of women filmmakers, Gyllenhaal pointed back to her remarks at Venice, where she served as jury president and only one woman had a film in competition.