Saturday, July 7, 2012


Polygraph test has been for some time now, and we see them all over TV and how there are ways to beat them. On “Ocean’s Thirteen” the one character was instructed to but a thumb tack in his show and press every time they asked him a question, or you can be like Al Pacino’s character in “The Recruit” and just able to beat it straight up. This raises the question if this device main purpose is to detected lies and deception, why is it able to be tricked at all?

I was initially confused when I looked through the book and saw the listing of polygraphs in this book, but to my defense I did not know what pseudoscience was and its definition. When getting to learn the subject matter it started to make perfect since why the polygraph is included in such a book. The polygraph is used to measure an individual’s physiologic responses to questions by measuring their breathing, cardiovascular activity and palm sweating. The way that it works is the operator of the test sits down and gives you several Control Questions, which are simple questions with known facts; this is to measure their physiological response to truthful questions. Then they will proceed to ask the questions in regards to the crime or act, and measure those physiological responses with the original control responses.

The reason why this falls under pseudoscience is because with these questions and all its efforts, there is no definitive link between physiological responses and if somebody is telling the truth or lying. Just because somebody starts to breath heavy and sweat at the palm doesn’t mean they are lying. There could be many other explanations. The individual may not handle being accused of a crime well, they may know something about the crime but were not a part of it, and they can feel nervous and not focus on the task at hand and wonder what if they were caught lying. On the other side of the coin you can get beat the polygraph by things like the tack in the shoe, to create a higher stress level throughout the interview including the control questions, also by creating more stress throughout the control questions and concentrate on other topics and control your breathing through the second part of the questions. The main goal of the polygraph is to manipulate the individual into believing that the device can tell the difference between a truth and a lie, and deter them from even lying in the first place or even have them just breakdown and confess. The polygraph falls under a couple of the pseudoscience characteristics, the one that stands out the most is the lack of progression. From as far as I remember the polygraph is the same things wires hooked up to an individual and a box that seems like a paper heart monitor, with long metal pens tracking the person’s heart rate, and when they lie they go crazy. With all the technology that has passed, it is pretty much the same setup, with the exclusion of the box because not it is on a computer. The polygraph is used (even though it can’t be used as an admission of guilt in the court of law) because of its placebo effect. It doesn’t work in the tradition way, such as a doctor telling you to take a sugar pill and you feeling much better. The way it works is that by making a person believe that this machine can tell if he/she is lying, the person will worry and feel the need not to hide the truth and just to come out an admit guilt because the machine is supposed to be able to already know.

I believe that the practice should be gotten rid of, I have taking a lot of criminal justice classes and see a lot of incidents on many crime shows that has shown false positives, or the guilty party passing the polygraph multiple times. It use is to fool the individual but with the increasing knowledge of how it works throughout the media, it seems that shouldn’t be used at all because of its potential risk to convict the wrong person and even let the right one go.  


  1. Great post. It seems that a lot of people don't realize just how inaccurate and unreliable polygraphs are. You see them referenced frequently and shown on television as though it is a magical device that is 100% foolproof.

    It's also been proven that one can "cheat" the polygraph tests. One can simply practice breathing exercises to maintain their heart rate and blood pressure so that it remains stable during the test.

    Additionally, I think polygraphs shouldn't be used in professional settings, such as employment. It's absurd to mandate a polygraph exam to police applicants. I've had a friend who took the test when he applied to become a cop. He lied through the entire test and still passed.

  2. Methods like the polygraph are themselves flawed as the chances the test to even prove positive could have just been the machine rigged to read positive in the first place, causing tension for the accused, who having just told the truth could be now having a fairly defensive posture since they were just accused of lying over a crime.