[Narrator] You’ve probably seen this device before. This is a polygraph, more popularly known as a lie detector. However, just how often it can catch you in a lie is debatable. (lively music) Thousands of polygraphs are administered each year in the U.S. alone, for everything from government clearance screenings to witness verification. The power of these machines’ results is not taken lightly. People have reportedly lost their jobs and reputations over a failed exam. But how exactly does this machine work? And is it really as accurate as polygraph examiners claim? To find out, we decided to put the polygraph to the test ourselves.
– Do you understand I’ll only ask you the questions that we discussed?
– Yes.
[Narrator] Polygraph results haven’t been accepted in most state courts since 1923, mainly because:
– The scientific research suggests that the polygraph has significant scientific problems. That is, it may not give us the level of accuracy, specificity, and sensitivity that we think it will, and that could be problematic.
[Narrator] Still, many defenders argue that even though the polygraph isn’t 100% accurate, neither is DNA testing or eyewitness testimonies.
– Do you intend to answer each question truthfully?
– Yes.
[Narrator] Now, what the examiner may or may not know is I’ve already told my first lie. So what we are going to do is try and lie and see if she can detect the lie. There are going to be questions that she asks me in various ways over the course of the exam, and one of them I am going to deliberately lie on to see if she can figure it out.
– Are you sitting down?
– Yes.
One of the ways you can manipulate the machine’s results is by controlling your breathing, ensuring you have calm breathing during the exam. I’ve done a few breathing exercises over the course of the week to prepare for this. So, when I get that question that I know I’m going to lie on, I’m going to make sure that my breathing is nice and calm. Or at least, I’m going to try.
– Have you used any illegal drugs in the last three years?
– No.
– Did you ever commit a serious crime? Were you ever terminated from a job that you did not disclose? In your whole life, did you ever do something you’re ashamed of? In your whole life, did you ever lose your temper? Are the lights on in this room?
[Narrator] Okay, the test is over. Let’s see if she caught my lie.
– You were relaxed, it’s going down, and then when it begins here, it’s going back up again.
– That’s so interesting.
– So it’s a lie.
[Narrator] So, yep, the polygraph caught me. Now, to be clear, this type of test is similar to what’s normally administered for job interviews, meaning the stakes are lower and the accuracy rate isn’t as high. And it caught me, anyway. But it’s hard to know if this is the case for your average person. Even though I worked on controlling my breathing, what really got me was my increased heart rate, perspiration, and blood pressure. So who knows what would have happened if I’d spent a little more time figuring out how to control those things. And that uncertainty is pretty much why most state courts try to steer clear of polygraphs. Because it’s known that people can and have beaten it.
– I’m of two minds about the polygraph. I have serious reservations about its use, but I can see that it might have some utility in some, but certainly not all, contexts. I think we need to be pretty conservative and cautious about its use.
Read More: The Role of Polygraphs in Ensuring Public Safety