While reading the papers last week I came across a story in China Daily concerning the polygraph (or lie-detector as it is also called). The story featured Guangzhou Psychiatric Hospital where they're applying for a permit to use the polygraph. One doctor is quoted as saying that it "can reach 99 per cent accuracy." It might be news to you, but that can at best be called bending the truth.
"How do you know?" you might say. I'm not an expert on the polygraph, but in December I called some experts to satisfy my curiosity. My first call went to John Furedy, professor of psychology at the University of Toronto, a widely published expert on the matter of the polygraph. He told me that there's no science behind it, because the polygraph only measures bodily responses that can vary from person to person. The responses can be manipulated easily to make someone appear truthful.
But one person isn't enough to convince me, so I called Doug Williams, a former police polygraphist who was in charge of police internal affairs in Oklahoma in the US. Having conducted thousands of polygraph tests, Williams said the polygraph has a "deterrent value," but it's a "thinly disguised excuse to interrogate people with a trained interrogator". This was confirmed by former US Federal Bureau of Investigation (FBI) agent Drew Richardson, with a Ph.D in physiology, who told me he went through the FBI's 14-week polygraph training programme and realized that anyone could be taught how to beat the test in a few minutes.
People in favour of the polygraph often cite its wide usage in the US court system. Nonetheless, a 1998 Supreme Court ruling reads: "To this day, the scientific community remains extremely polarized about the reliability of polygraph techniques ... scientific field studies suggest the accuracy rate of the 'control question technique' polygraph is 'little better than could be obtained by the toss of a coin,' that is, 50 per cent" (The control question technique is a widely used technique where the real questions are mixed in with control questions to measure a person's "truthfulness").
When you see the polygraph on television and in films, it seems like a great device for finding the truth. So why not use it? A rapist or a murderer may confess under a polygraph examination. But the real risk of innocent people, who are just nervous, being found "deceptive" by the pseudo-science of the polygraph isn't worth it. The people lying here are the ones calling the polygraph science. But then again, who can you trust these days. Take a look at www.antipolygraph.org, www.polygraph.org and www.polygraph.com to find out for yourself who's lying.
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