In age of distrust, usage of lie-detectors surges

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In age of distrust, usage of lie-detectors surges


A polygraph measures changes in heart rate, blood pressure and galvanic skin response as a subject is asked questions at the International Forensic Science Laboratory in Seocho District, southern Seoul. By Oh Jong-taek

A 56-year-old executive of a medium-sized company who doesn’t want his name in print was having trouble with his wife. She was convinced he was unfaithful to her, and nagged him constantly about it.

The husband was faithful. But how could he prove it?

In March, he came across the Web site of the privately run International Forensic Science Laboratory. It offers fingerprint analysis to private customers and polygraphs, or lie-detector tests. The executive decided to have himself polygraphed as his wife watched. His examiner was Choi Hyo-taek, a 30-year veteran of the National Forensic Service, which does the polygraphs for police and other public investigations. The exams cost from 600,000 won ($525.23) to 1.5 million won. The test took two to three hours, and concluded the man was telling the truth when he said he didn’t cheat on his wife.

“My wife’s delusional jealousy got serious after she was diagnosed with depression,” said the husband. “But she stopped taunting me after the lie detector said I’m innocent.”

Polygraphs measure physiological changes in heart rate, blood pressure and galvanic skin response as the subject is asked a series of questions. The theory is that people feel stress when they try to hide or distort information, and that the stress is reflected physiologically.

Control questions on neutral subjects - the subject’s name, address, age - are supposed to provide stress-free physiological results. The reactions to the questions pertinent to the inquiry - such as “Have you cheated on your wife?” - are compared to the control question answers to see if they show any signs of stress.

The polygraphers assume the subject is lying when the responses to the pertinent questions are stronger.

“The reliability depends on how well the examiner asks the relevant questions and properly compares them,” said Choi, the detection professional.

The use of polygraphs in law enforcement is on the rise. The number of people given lie-detector tests during police investigations jumped to 5,974 last year from 3,747 in 2008, according to the National Police Agency. The International Forensic Science Laboratory opened in 2011 in Seocho, southern Seoul, and has performed 110 examinations so far. It has five staff members, three of them professional examiners, all of them from the National Forensic Service.

Of all their customers, married couples with some kind of issue accounted for 43 percent. Most wanted to know if their spouse was cheating.

“Twenty percent of the tests conclude the spouse is lying about not having an affair,” says Choi, “and the couple usually starts arguing as soon as they learn the unpleasant result.”

Around 80 percent of the spouses are exonerated by the tests.

The second-largest group, 29 percent, are people involved in civil suits who want to prove their side of a story. The results of a test are rarely admissible as evidence in a court, but they can be circumstantial evidence when agreed upon by both parties. Sometimes they make an impact on judges.

The third-largest group, 19 percent, are employees of companies trying to clear themselves of a false accusation such as spying for the competition, according to the center.

Unlike in the United States, it’s extremely rare for Korean companies to use the polygraphs to discipline or hire an employee.

The center is now getting around two customers a week.

The price of the polygraph machines, which are imported from the United States, is 40 million won each. For that reason, industry insiders don’t expect rivals to spring up soon.

But how reliable are the tests?

The National Forensic Service claims up to 97 percent accuracy, but there are plenty of counterarguments and skeptics as well, especially in the West.

In the United States, some states allow polygraph evidence to be used in courts, but many do not. In a 1998 Supreme Court case, the United States v. Scheffer, the majority opinion advised, “There is simply no consensus that polygraph evidence is reliable.”

The U.S. National Academy of Science in 2003 also suggested that the majority of polygraph research was “unreliable, unscientific and biased.”

Also, unless investigators have enough information about the crime or case to frame their questions carefully, they run the risk of making hasty conclusions based on just one or two “deviant” responses.

Despite the criticism that polygraph evidence is patchy, technology keeps evolving to provide more advanced machines that include eye movement detection and even brain scanning, which will undoubtedly keep the machines in use - and keep controversy about them alive.

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