Cameron Diaz hung out with her director's parents to prepare for a movie role.

The actress says that her character Norma in 'The Box' was based so closely on filmmaker Richard Kelly's mother, she decided the best way to work on her accent and mannerisms was to spend time with her.

She explained: "Norma and her husband Arthur — played by James Marsden — were literally based on Richard's parents. His father did exactly the same job as Arthur and Norma has the same disfigurement of the foot his mother had. The film's his interpretation of their love story and their dedication to one another.

"I spent time with both his parents. His mother was very generous with her experience about how her foot became disfigured and the way it happened for her was in the story. I also did her accent, she's from northern Texas and spent time in Virginia so she had a mutated accent, so there was a lot there to get into that was tangible for me."

The actress also revealed she doesn't consider audiences or the likelihood of commercial success when she chooses her film roles.

When asked if she thinks about external factors when reading scripts, she told Moviehole: "No, you can't, you just have to do it for yourself. I read 'The Box' and it spoke to me because of what it was tackling, and knowing Richard Kelly was telling the story was very exciting."