Behind the Scenes: WMW's Parella Lewis sits in 'hot seat' of WSP's lie detector tests
OLYMPIA -- Being able to detect a lie is something police have to do all the time, but once someone's hooked-up to a lie detector machine -- finding the truth hits a whole new level. “Everybody fears the detection of their deception,” according to Det. Sgt. Ted DeHart with the Washington State Patrol. That’s the basic thought behind lie detector tests which have been used since the early 1900's, but what started as a needle and paper printout is now a laptop with charts, graphs and a lot of science. “There’s over 20 things that happen simultaneously when somebody hears a question and decides to lie to it," says Det. Sgt. DeHart. "Internally there are neurons firing-off different nerve endings and your sympathetic, parasympathetic nervous system is now trying to come to a neutral or balanced state, but when they hear a lie and tell a lie their body reacts to that." And those reactions are measured in a person’s blood pressure, breathing, body movement and nerve activity.
But just how accurate is it really? I sat in the hot seat to see if the machine could catch me in a lie. Det. Sgt. DeHart asks, “ Did you consume any alcohol that you did not tell me about before coming here today? I answer, "No.” DeHart asks another question, “Are you afraid I’ll make an error on this test?” I respond, "No.” However, as soon as a lie was told I was caught. DeHart asked, "Do you intend to lie to any test question here today?” I answered, "No.” After the test was over the charts were clear as to where my “lie” was. DeHart explains, “This is your blood pressure and see right here where it went from wide to thin, question 3, you really started thinking about it and your blood pressure started going up but I’m scoring this right here. This is telling me you’re having a huge reaction right here.” "Reaction" is a nice word for lie and because so many things are being measured at one time, DeHart says it really isn’t possible to beat a polygraph machine. “The pathological liar or somebody who really doesn’t care if he lies or not or they lie, they still internally have those same things going off in their body,” DeHart says. But what about the man who does this for a living? Could he beat the detector he knows so well? I decided to test this theory. I asked, “Do your friends call you Ted?" Dehart says, “Yes.” I asked another question, “Do you like donuts?” DeHart says, “No.” I asked my final question, “Are you a late night snacker?” DeHart answers, “Yes.” It turns out that he loves donuts and his chart gave him away. At the end of the day polygraph tests are not admissible in court unless both the prosecuting attorney and the defense agree to allow it. Still, law enforcement and many employers across the country use this as a way to weed out potential bad seeds. It’s used hundreds of times a year by Washington State Patrol and is another helpful tool that sometimes helps them read between the lines. DeHart adds, “If somebody has made a statement and we want to verify that statement we could ask them to volunteer and take a polygraph and confirm what their statement is."