Clockwise from top left: Richard Perry / The New York Times; Keith Meyers for the New York Times; Hiroko Masuike for The New York Times; Stephen Crowley/The New York Times; Greg Gibson/Associated Press; Associated Press.

Video Expressing Shame When Rep. Anthony D. Weiner of New York admitted lying at a press conference Monday, Dan Hill, an expert in the role of emotion in consumer behavior, was watching. Watch Video »

The names may change, but the face remains essentially the same.

Politician after politician, in scandal after scandal, faces the cameras with his lips pursed and pulled tight, narrowing them. The chin boss — the fleshy bump above the chin bone — is pushed upward, pulling the lips into an upside-down smile. Add a downward-cast gaze, perhaps a shake of the head, and: Instant Disgraced Pol.

On Monday, Representative Anthony D. Weiner became the latest in a long and unfortunately distinguished line of officials whose faces appeared all over the news wearing an expression that instantly telegraphs powerful-guy-confesses-impropriety.

Former Gov. Eliot Spitzer of New York is perhaps the standard-bearer of this parade as he admitted to patronizing high-priced prostitutes.

But President Bill Clinton, during the Monica Lewinsky scandal, and former Gov. James E. McGreevey of New Jersey, when he announced that he was gay and had carried on an affair with a man, wore it too during their public falls from grace.

Likewise, there were Eric Massa, a former New York congressman who resigned after admitting to an inappropriate exchange with a state aide, and former Senator John Ensign of Nevada, who resigned during an ethics investigation related to his affair with the wife of a former top aide.

To interpret the meaning of that now-familiar face, City Room called upon Dan Hill, the president of Sensory Logic, a market-research firm in Minneapolis that uses facial expressions to quantify emotional response. He is also the author of “Emotionomics.” Here, in an e-mail and in a telephone interview, was his explanation: