Pete Williams of NBC News reports. Excerpt:
July 17 — Even though Rep. Gary Condit’s lawyers have now turned over the results of their own lie detector test, Washington, D.C. police still want the congressman to take one of theirs. All of this has brought the science of lie detectors front and center. How do they work? How reliable are they? Can they be fooled?
IT’S AS elaborate as any interrogation can get — tubes across the chest to measure breathing, electrodes on the fingers to monitor sweating, a cuff on the arm to chart blood pressue. But can a polygraph really indicate what’s going on in someone’s head and detect a lie? And is there a way to beat it?
Nearly every police department in the nation relies on polygraphs for questioning, and even skeptics conede that guilty suspects sometimes confess if they think the machine is infallible.
“Some people have called the lie detector a psychological rubber hose,” says Professor William Saxe of Brandeis University.
But what if someone thinks the device isn’t perfect. Can it be fooled?
“Dateline NBC” tried to test that question in a recent lie detector examination of correspondent Rob Stafford, conducted by a former supervisor of the FBI’s polygraph unit.
After answer questions about the date and his name truthfully, Stafford decided to lie, to see if the examiner could catch it.
“Have you ever violated a traffic law?” asked the examiner, Richard Kiefer [sic, correct Keifer].
“No.”
“Are you lying when you said you have never violated a traffic law?”
“No.”
Kiefer concluded it was a lie, based on results showing clear stress on those answers. And he says a demonstration is one thing — covering up a lie about a crime would be even harder.
“A person cannot suppress a reaction to an important relevant question,” says Kiefer.
Polygrapher Richard W. Keifer didn’t need to gaze into any polygraph charts to reach the opinion that Rob Stafford was lying when he denied having ever violated a traffic law. This is a question that virtually no one who drives could truthfully answer “no.” While this NBC report goes on to discuss polygraph countermeasures with Doug Williams, it refrains from exposing the trickery on which polygraphy depends (for an exposition of which, see Chapter 3 of The Lie Behind the Lie Detector.)