The truth, the whole truth, and nothing but the truth

Patty here…

Anybody out there ever take a polygraph AKA lie detector test? I did as part of a recent class I took. None of the other forty students volunteered to participate in the demonstration, so I found myself raising my hand toward the dimpled ceiling tiles of a frigid meeting room at the Holiday Inn. There is an old expression that cops sometimes use, “Send her to poly and put her on the box.” There’s no box anymore. I was going to poly but my responses would go directly into a laptop computer.


Use of the polygraph began in the late 1800s and the practice continues to generate controversy, which is why the results are not admissible in a court of law, at least not in California. As most of you know, the purpose of the test is to register a person’s physiologic responses to various questions. Monitors on the body simultaneously record changes in blood volume pulse rate, skin resistance changes, and respiration rate. Since you can’t control the perspiration on your fingertips or your blood pressure, stress levels associated with certain questions can help examiners evaluate whether or not your answers are truthful. What the examiner is looking for is consistency of reactions. That’s why he asks the same question multiple times.

Before the test began, the examiner proposed a series of informal questions. He told me in advance that he would be asking me a simple math question. My relationship with math is tenuous, but I was convinced I could suck it up and crunch the numbers. In fact, I consider myself fairly cool under pressure, so I was even feeling a bit smug.



After he explained the procedure, an assistant placed monitors on my fingertips, a blood pressure cuff on my arm, and tubes that crisscrossed my chest and abdomen. The tubes were tighter than I’d anticipated, making that Fuddruckers burger and French fry lunch seemed less like a good idea. For a moment, I imagined myself being interrogated under a naked light bulb in a 1940s noir film.

I was not allowed to look at the examiner during the test. His first question was, “Is your name Patty?” I said yes, even though my name is actually Patricia. After several more questions, all spoken in a low monotone, he dropped the math bomb.

The calculation was relatively simple, something like, 14 times 9 minus 7, but the idea of 40 people watching me count on my fingers and toes created a flashback of my seventh grade math teacher, tapping her pointer on the blackboard in a horrifying exercise she had created to teach us rapid addition.

“One hundred nineteen,” I said.

Without pausing, the examiner went on to the next question.

After his assistant unhooked me, the examiner showed my results to the class. The math question had spiked my blood pressure like crazy. That segment of my chart looked like the Pyrenees Mountains.


In other words, the question had elicited strong emotions, rendering my answer “inconclusive.” Even though I wasn’t lying—14 times 9 minus 7 is 119—my truthiness had taken a hit.

The class immediately questioned why the machine hadn’t detected the lie when I’d answered yes to the Patty question and why a truthful response to a math question was pronounced “inconclusive.” I wondered what would have happened if the question had been “Did you kill Roger Ackroyd?” What if I'd answered no truthfully, but because the question triggered a negative but unrelated Agatha Christie flashback, the hike in my blood pressure made it seem as if I was lying?

Of course, my test was only a demonstration. A real polygraph would have been longer and more complex. Still, it generated some interesting issues. Does anybody other than me feel a short story kicking around in your head?

Feeling confident? Here are a couple of interesting sites about beating the test.

Happy Monday!

P.S. Here's a picture of Groupie and me at the Mysteries to Die For book signing on Saturday.