Guillermo Del Toro's Secret Technique For Helping Rooney Mara And Others In Nightmare Alley - Exclusive

Every director has their own methods for getting the best performances out of the actors with whom they work. Stanley Kubrick secretly filmed George C. Scott during rehearsals for "Dr. Strangelove, or: How I Learned to Stop Worrying and Love the Bomb" so that he could get a more comedic interpretation of Scott's crazed general Buck Turgidson than Scott was willing to offer on camera. William Friedkin slapped real-life priest William O'Malley in the face to get the right kind of emotional response out of him during a crucial scene in "The Exorcist."

"The Blair Witch Project" directors Eduardo Sanchez and Daniel Myrick left their three stars in the woods with a bare outline of the story, making them film themselves and improvise their lines while the directors did everything they could to terrify the actors during the night (via EW). Keanu Reeves was given several books to read by the Wachowskis on "The Matrix," including philosopher Jean Baudrillard's "Simulacra and Simulation," so that he could fully understand the film's concepts.

Guillermo del Toro, director of the new "Nightmare Alley," has a much less intensive — and hopefully far less taxing — approach that he uses on every one of his movies. Rooney Mara, one of the stars of "Nightmare Alley," worked with del Toro for the first time on this film and tells Looper that she "really loved" the director's procedure — so much so that she used it on her next project.

According to the Los Angeles Times, Guillermo del Toro writes out a "four-to-eight-page" biography of every major character in every film he makes. He's apparently done this as far back as his very first movie, "Cronos," and even released examples from "Pacific Rim" and "Crimson Peak" online a few years ago(via Nerdist). The actors are free to use what they want from the bios (or even nothing at all) to help them understand their characters and flesh them out on screen.

Del Toro continued the tradition for "Nightmare Alley" and found a fan in Rooney Mara, who plays carnival performer Molly Cahill. "I really loved it," she says. "I think it was useful. I actually then poached that idea for the next film I did. I made one for myself just because I loved it so much."

Mara admits, however, that not of all of what is written in the bio necessarily makes it to the screen or even into the actor's thoughts. "As an actor you gather all this stuff and information, and then at least you hope that on the day you throw that all away," she continues. "Maybe it's somewhere inside of you, but you're just there, in the present moment. That's how I find it anyway."

While the cast members of del Toro's films are free to use whatever they want from the character biographies that the director provides, actor Richard Jenkins — who has worked with del Toro on "The Shape of Water" and plays corrupt industrial magnate Ezra Grindle in "Nightmare Alley" — reveals that it wasn't something that interested him.

"For my character in 'The Shape of Water,' he wrote a beautiful biography," explains Jenkins. "I mean, it was really beautiful. And he said, 'Did you read it?' I said, 'Yes.' He said, 'Are you going to use it?' I said, 'No, I don't think so.' And he said, 'Why?' I said, 'Well, it's lovely, but I can't figure out how I feel about my mother. How does it manifest itself in this movie? Because it's not in the movie.' I added, 'It just confuses me, because my brain has to be a little clearer than that. I can't ... all that information.'"

Jenkins, a consummate character actor, went on to give a fantastic performance as the lonely, closeted artist Giles in "The Shape of Water," earning Oscar and Golden Globe nominations — among many others — for Best Supporting Actor. When Jenkins didn't win, del Toro playfully reminded him about the unused character bio. "When I lost the first awards show, at the Golden Globes I think, or something, he was sitting right next to me," Jenkins recalls. "When I lost, he said, 'If you'd used the back story, you might have won.' And, then every award I lost after that, he would mime tearing up the back story."

"Nightmare Alley" is now playing in theaters.