"I haven't seen the show. I haven't seen The Mentalist," said Roth
"I think the proof is in the pudding. ... We are what we are."
Roth plays Cal Lightman, a master of reading people's faces and body language to tell whether they're lying. The Mentalist stars Simon Baker as an investigator whose ability to read people is so powerful he seems capable of reading minds.
But Lie to Me executive producer Brian Grazer says what separates the shows is science.
"I'm not really interested in The Mentalist's process," Grazer said. "I mean it might be good - I mean I think it is good, it's doing really well - (but) I'm actually interested in whether people are telling the truth."
Lie to Me, which debuts Jan. 21 at 9 pm/ET, is based on the work of Paul Ekman, who has studied lie-detection techniques for more than 50 years. Roth's character uses the techniques to solve a wide range of mysteries: political plots, murders, and even - in the third episode - whether a man's fiance loves him or his money.
"The show is based on real science, the most cutting-edge research that's used by our federal agencies in national security," executive producer Samuel Baum said. "One week we're going to be a thriller where there's a political assassination and the next week there's a terrible building collapse and people are lying about it and pointing fingers as to what happened. Some weeks there won't even be a crime."
At a news conference with the show's creative team and stars - who also include Kelli Williams and Brendan Hines - Ekman described some of the subtle signals people send without realizing it. Barack Obama, for example, sometimes touched his head with his middle finger to express irritation toward Hilary Clinton and John McCain.
"If you were on-set yesterday, you would have seen Kelli Williams do that to me twice," Hines said.
Baum, the director, says he's also picked up a few lie-detection techniques - but he has to see people face-to-face to use them.
"My agents won't deal with me except on the phone," Baum said. "They say they can't do their job if they can't lie."