Robert Pattinson was cast in Cosmopolis because he didn't understand it.

The British actor plays billionaire tycoon Eric Packer in the movie - set in a futuristic New York, which is in turmoil because of the decline of capitalism - and thinks being "lost and confused" when reading the script worked in his favor.

"It's funny, I kept saying when I read it, 'I can't understand,' I told David [Cronenberg, director] I didn't understand it. I kind of still, I watch it and I want to imagine something else, and I guess that's how I was trying to play it, like just imagining something as something else the whole time, and not being able to identify it. David quite quickly realized that what he liked was when I didn't have any idea what I was doing, like I mean I was sort of sitting there, completely lost and confused, and he was like, 'That was the one!'"

Despite Robert's reasoning, David insists there is a much more "pragmatic" approach to his casting of a role:

"Well it starts when you're casting in a very basic, pragmatic way. You say, 'OK, what is the age of the character?' And then you have to cross off your list of actors all the actors who are too young or too old, you know, and then it's, 'OK, he plays an American, that means he's either an American actor or an actor who can do a good American accent,' so you cross more off the list. Gradually you find yourself with a very small list of actors, and then not surprisingly if your movie is relatively expensive, and for us, compared with a Hollywood blockbuster it's cheap, but compared with most independent films, it's, it's right at the top level, you have to have an actor whose fame will support the budget that you have, so that makes the list even shorter."