Sam Rockwell gets so much enjoyment out of researching his roles, one might think he’s just in it for the free field trips. Take his new movie, “Choke” (Sept. 26): Rockwell’s character, Victor Mancini, is a Colonial theme-park worker who, in his off hours, is a scam artist and compulsive womanizer.

Naturally, he delved.

“Yeah, I went to a few sex-addiction meetings,” he says. “One time I went incognito and said I was an addict. That might seem intrusive or like a boundary that shouldn’t be crossed, but we want to respect the illness. As artists. The only way to do that is to do research.”

Turns out Rockwell had a little personal experience to draw on, too. “I’ve had my own history – I’ve been to prostitutes and massage parlors and stuff,” he says offhandedly. “Back in the old days. So, I understand the mindset a little bit.”

The actor’s happily in a relationship now, but that didn’t stop him from appreciating Victor’s plight.

“Being single on and off, over the years, you start to kind of wonder, why am I still single? Why do I keep f – – – ing up relationships?” he says. “Anybody who’s in their 30s and can’t get it together can relate to that. I think that’s a lot of us.”

Of course, Rockwell isn’t exactly unemployed and living in his parents’ basement. After “Choke,” he’ll appear in “Frost/Nixon” (Dec. 5). The Ron Howard-directed film is based on the Broadway play; Rockwell plays journalist James Reston Jr. (“Oliver Platt and I are probably the comic relief in the movie,” he says).

As his schedule might suggest, Rockwell’s not big on down time; when left to his own devices, he says, “I drink beer and eat too much ice cream.”