Asked by Ellen DeGeneres if he's shy – and thus prefers acting to talking about acting – the Twilight heartthrob, 24, replies: "I just like doing things where you have a little time to think about what you're saying. I've always had a problem actually thinking before I open my mouth."
"Being spontaneous?" Ellen asks. "Yeah, being spontaneous or just thinking," he says. "I have a problem with thinking."
In the interview, airing Wednesday on The Ellen DeGeneres Show, Pattinson also explains his new, shorter haircut. "It's three days old," he says. "I got a terrible infestation of nits and I had to shave it all off."
"No you did not. Don't start that rumor," Ellen says.
Okay, it's for a film, he admits. He begins shooting Water for Elephants, costarring Reese Witherspoon, in Los Angeles on Thursday.