A Polygraphal Experience
17 Jun 2008 
around lunchtime 
Matt Winckler
Probably the most interesting and/or stressful part of the KPD application process thus far was the polygraph examination. There is a plethora of information on the Internet about the polygraph exam, most of which decries the practice as “black magic”, “voodoo”, and generally unreliable. The majority of these diatribes seem (to me) to stem from people who have failed polygraph exams. You can also find a load of information on how to “beat” the polygraph, using a variety of techniques from sticking tacks in your shoes and pushing your toes against them when answering, to performing some sort of Kegel exercise while answering. Before taking the polygraph, I looked at these sorts of articles with a dubious eye; after the polygraph, I look at them with scarcely concealed scorn.
I’d never before seen a polygraph machine. In one sense it’s an impressive setup, but in another sense it’s rather underwhelming. There is a chair in which you sit that has pads on the seat and both armrests. Two bands go around your chest, and the bands expand and contract with your lungs to measure your breathing. Two metal half-rings held on by Velcro go on two of your fingers, and on another finger goes one of those clip-on measuring things that hospitals use, the name and purpose of which I can never remember. Finally, there’s also a blood pressure cuff armband. The polygraph examiner (who in my case bore some resemblance to that SS interrogation officer in The Great Escape, but actually turned out to be a nice fellow) also has you take off your shoes. (So much for the tacks!) All these sensors measure more things than I can remember, including heart rate, breathing rate, the amount of (some-fancy-word) sub-dermal sweat (the sweat beneath your skin), your blood pressure, your arterial blood flow rate, and so forth. More things than you could ever hope to intentionally fake, anyway.
The whole ordeal started off with a comprehensive interview, consisting of pages and pages of questions designed to ferret out every minor sin you have ever committed in your lifetime. (This was, in my experience, hands-down the most unpleasant part. And I’m pretty clean!) Following that, he explained the way the polygraph machine worked, and demonstrated the extreme sensitivity of the armrest pads by gently setting a ball-point pen on one of them–which resulted in a spike on the graph of that sensor (displayed real-time on a laptop nearby). He also described the fact that some percentage of folks do fail the polygraph, but these fall into two categories: the ones who are lying to cover something up, and the ones who are truthful, but (for whatever reason) are trying to use some technique to “enhance” their results. (I suppose that these would be the truthful ones who are completely distrustful of the polygraph process in general.)
Next he went through the questions that would be asked on the polygraph (only ten or so, of the yes/no variety), so that I would be certain of how to answer. He gave me the questions to read to make doubly sure there were no surprises, and then got me all hooked up to the apparatus. The fascinating part came when he asked the “calibration” questions, consisting of some simple math (e.g. “What is 4 plus 1?”) He asked one and told me to give a verbal response, and then asked another and told me not to give a verbal response, but simply to think of the answer. Evidently merely the act of thinking the response is sufficient to make some impression on one or more of the sensors. Finally, the questions began.
He went through the same set of questions three times, presumably to get an average of charts to examine. After that, he spent some time analyzing and interpreting the results. He told me that although I had some minor “reactions” to certain questions (he didn’t say which), he didn’t see anything that indicated deception. (Which is fortunate, since I was telling the truth.) At this point it was all over, and I left him to continue interpreting the results and formulate his report.
All in all, having now taken one, I have no problem with the polygraph concept whatsoever. I still think it is prudent that it is not admissable in court as evidence, but I have no qualms with the state of Washington requiring one as part of all law enforcement hiring processes (as it does). The reason I think it should stay out of courts is that it does rely upon the interpretation of the examiner, which introduces that small margin of error which, though doubtless very small, is still big enough in my mind to warrant limitation to lower-stakes applications such as employment background checks. (If someone doesn’t get a job because of an erroneous polygraph interpretation, it’s too bad, but not that big a deal. If somebody gets a life sentence on the basis of a false interpretation, on the other hand, that’s a big deal.) It will be interesting to see how technology continues to advance in this area.
Interesting! I’d be curious to try taking one of those some time. Did he ever ask you to lie to see if it’d register right? If you said 4 + 1 was 6, would it really change the results it gave?
Though I’ve read about those sort of “intentional lie” questions, this examiner didn’t have me do that. Had he done so, I’d presume that it would have shown through on the results, though maybe in different ways from “normal” lying. My understanding is that a big part detecting deception is watching for the additional thought and stress that goes along with trying to maintain the consistency of your false story. Perhaps that wouldn’t be played out so much in the case of intentionally lying to an answer, because you wouldn’t care whether it was consistent later on or not. That’s just a wild guess on my part, though; I don’t know the real reason.