The Polygraph Paradox
Lie detectors aren’t perfect. But, convicted sex offenders concede, they may be good enough
By LAURIE P. COHEN
March 22, 2008;
Klamath Falls, Ore.
The lie detector won’t die.
Polygraphy, the attempt to ferret out deception by monitoring changes in subjects’ breathing, sweating or pulse, has long been derided as “voodoo science.”
Confessions made under polygraph aren’t admitted as evidence in a vast majority of U.S. courts without the consent of the accused. The National Academy of Sciences says the technology isn’t accurate enough to be used for employee security screening.
Yet polygraph use is at the highest level in two decades. Government agencies from local police departments to the CIA are increasingly using the technology for job interviews. In U.S. courts lately, judges have expanded the instances in which polygraph testing is mandated or admitted as evidence.
In law enforcement, this lie-detector paradox is clearly on display. Polygraphy is a centerpiece in an expanding range of parole and probation programs that are designed to dissuade sex offenders and other felons from committing more crimes.
The recent experience of convicted gay pedophile Paul Duncan shows the polygraph’s contradictions and, its proponents argue, its promise. Last November, as part of a program in this southern Oregon town to monitor paroled sex offenders, Mr. Duncan sat in a small windowless room in a corrections center with polygraph sensors on his palm, chest, stomach and arm. Under the program, a parolee who fails the test, or admits to parole violations under the threat of a test, can be sent back to prison.
The machine’s operator asked: “Have you had sexual contact with a minor during the last six months?”
Mr. Duncan said he hadn’t. The polygrapher judged him to be lying. Mr. Duncan was sent to jail for 15 days.
In an interview after his release, the 33-year-old Mr. Duncan said reality had been more complicated. Mr. Duncan said he hadn’t, in fact, had contact with a minor. But he admitted he had violated his parole in another way — viewing online pornographic photos of young males, an activity he says had sparked his past pedophilic episodes.
Mr. Duncan says he believes that while the polygraph got the specifics wrong, it revealed a broader truth: His conscience was guilty.
“I didn’t disclose my deviant fantasies — and I deserved to fail,” Mr. Duncan said of the test. “Don’t believe anyone who tells you polygraph doesn’t work.”
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