Your character, Madison, isn't the most endearing role you'll ever play...

She is one of those on an actor's wish list. You want to play someone who is just over the edge, and I had a blast doing it. I mostly have fun wherever I go and whatever I do, and I really did have great fun playing her. But you're right, she's not exactly the most endearing role, but these things balance out. In "The Perfect Score" [a college crime comedy, co-starring Scarlett Johansson], my character is a much nicer person.

Did you realise that "Traffic" would be such an important film for you?

I had a clue, yeah [laughs]. I practically hyperventilated when I got the job.

And since then you've filmed "Swimfan" and "The Banger Sisters"...

Yeah, "The Banger Sisters", that's a comedy. It was a blast. Oh my God, you can imagine the experience of watching these women... Goldie [Hawn] and Susan [Sarandon] are legends, just watching them work was really great for me. They had a great balance between being a real pro, and having fun and having a great sense of humour.

You acted all through your teen years. Did you feel that you missed out on school life?

I think I gained in other ways. I have absolutely no regrets because I knew so strongly that this was what I wanted to be doing. And I'm so glad that I was able to. I mean, my life would have been so different if I had only started acting a year ago when I was 18, but as it turned out I did home schooling, I got my diploma at 16, I made "Traffic" at 17, so my life is much more on the course I wanted it to be on - acting.

Do you look very much to the future?

I do. I take things on a day-to-day basis when it gets really hectic. But I do think long term, and I'm looking forward to the next couple of years when I start producing my own films with my production company and playing some characters that are older. That's really exciting to me.