Pants on fire? Thermal imager may reveal a lie

Coming one day to a government checkpoint near you: a thermal imager that just might tip off a guard to a liar.

The research arm of the Defense Intelligence Agency has been working since 2000 on a camera that measures minute changes in facial skin temperature. Those fluctuations- involuntary and undetectable even to the owner of the face - indicate a stress response.

And that might signal you're telling a lie, says Troy Brown, chief of research at the DIA's Defense Academy for Credibility Assessment in Fort Jackson, S.C.

The DIA is deeply interested in deciphering deception in job candidates applying for positions with access to classified information and in prisoners captured on the battlefield undergoing interrogation.

So far, the only way the government can get an inkling that someone may be less than truthful is a polygraph, the so-called lie detector test.

DIA is now developing the camera as a more passive method of discerning stress. It hopes the camera will be able to assess truth telling without having to hook up interviewees to wires.

The camera could be used at border crossings, crime scenes and terrorist attack sites, and in interrogations and interviews.

The intelligence agency, which trains all government polygraphers, wants an automated tool that can help officials quickly sort through large groups of people to find those who may know more than they are telling, Brown said in an interview with The Associated Press.

The thermal imager may come close. It passively monitors fluctuations in body heat down to 1/100th of a degree that characterize a stress response.

That stress doesn't necessarily relate to lying, but it is a clue to an interviewer that they should dig deeper on that subject, Brown said.

The camera so far has proven useful for formal questioning, but not in the free-flowing environments the government wants to use it for, Brown said. He hopes additional research will sort those problems out and expects to have a system ready for practical use in about five years.