In a key scene in the new Coen Brothers Western True Grit, Damon, playing a boastful Texas Ranger, takes his costar Hailee Steinfeld – who turned 14 last week – over his knee and wallops her with a wooden reed. But that's a long way from Damon's real life with his four young daughters.
"I definitely don't spank 'em," the star, 40, told PEOPLE at the movie's New York premiere on Tuesday.
Attending the gala screening with wife Luciana, Damon said he and the filmmakers took precautions to make sure Steinfeld wouldn't actually get hurt filming the spanking scene.
"It's a scene in the movie that needs to be there for a whole host of reasons," he said. "And so, they just put a big pad on Hailee. And we practiced. And I said, 'Hailee, does that hurt?' And she said, 'I can't even feel it.' "
The whole family got to visit Damon on location for the Western, which was shot in New Mexico and Texas and stars Jeff Bridges as U.S. Marshal Reuben J. "Rooster" Cogburn, the role that won John Wayne a Best Actor Oscar in a 1969 screen version. This new take on the tale more closely follows the 1968 novel by Charles Portis. (The singer Glen Campbell played Ranger La Boeuf in the earlier version.)
"They were interested in seeing the horses," Damon said of the family visit to the set. "So, we got some pictures of them with the horses."
At home, is it tough to control four young women running roughshod? "Yeah, it's kind of nuts," Damon says. "The alarm goes off, and [expletive] starts flying."