Lie Detectors/Polygraphs

Lie detector test have become a popular icon in today’s culture.

Would it surprise you to know that according to an article from the American Psychological Association (APA), most psychologists agree that there is little evidence that polygraph tests can accurately detect a lie. [i]Psychologist Leonard Saxe, PhD, has argued, the idea that we can detect a person's veracity by monitoring psychophysiological changes is more myth than reality. [ii]

The polygraph was invented in 1921 by John A. Larson, who was a police officer and physiologist in California. There were other people working on the same thing as back as 1914. The device simultaneously measured continuous changes in blood pressure, heart rate and respiration rate to aid in the detection of deception. I’m not going to get into al the history because it’s very repetitive. If you want to know more of the history that is a good article published in Crime Psychology Review.[iii]

As a former law enforcement officer, I can tell you that in my opinion, the polygraph is a joke. I know of innocent people who failed them and guilty people who have passed them. I agree with the APA, except I’ll go further and say that from what I’ve witnessed there is NO evidence that polygraph test can detect a lie.

As much as I admired former US President Ronald Reagan, in 1983 he issued the National Security Decision Directive 84, which authorized all federal agencies to use polygraphs (commonly known as lie detectors) to test if any of their employees had leaked classified information. However, he corrected what I call a mistake and rescinded directive 84 less than 3 months after the issue because of multiple protest and a review by the Office of Technology Assessment (OTA). The OTA determined that guilty knowledge tests were biased toward false negatives and controlled question tests were biased toward false positives. The have been other studies to dispute these findings. I rely on what I’ve seen with my own eyes. In my experience the OTA study was correct.

There are two different methods used in polygraph examinations. The CIT and CQT. Both Methods use the same polygraph machine and agree that certain psychological processes result in physiological cues that can be measured and interpreted with the polygraph for the purpose of aiding in the detection of deception.

The CQT method tries to detect deception by measuring the physiological arousal patterns that result from the emotional states that the production of deception is argued to evoke, i.e. fear/stress. This method is based on the emotional deception detection approach developed by American psychologist Paul Ekman. In 1985 Dr Ekman wrote a book titled “Telling Lies”, and in response, national and regional law enforcement request his training. Ekman developed in-person workshops for TSA, the CIA, the FBI, and online training tools for the public. [iv]

Dr. Ekman states that deceptive individuals will likely experience different emotions than someone who was telling the truth would. According to Dr. Ekman the fear and stress associated with getting caught are the most commonly cited examples of such an emotion and are argued to result in deception cues such as gaze aversion, increased movement, speech errors, increased heart rate and perspiration. The increased heart rate and perspiration are in line with what CQT is supposed to detect.

The problem is that Dr. Ekman’s approach does not consider deception to be invariably fear inducing or stressful, maintaining that deceptive individuals may well experience a range of other emotional states.

That seems contradictory to me.

CQT relies heavily on invoking a stress/fear response in someone the examiner believes is lying.

The CIT method relies on physiological signs of emotion known as an Orienting Response. It describes someone’s reaction to a distinct or significate change in their environment.

The detection of deception through this technique with the CIT is not affected by the same problems associated with CQT.

So why since being brought into existence by John E. Reid in the late 1940s, has the CQT remained the most widely used polygraph test? [v] Since the CQT method is the most used that’s where we’ll focus attention.

There are 3 stages to the CQT examination.

The first stage is the pre-examination interview. It is normally done before the person being given the polygraph has been hooked up to the machine, but that not always the case. This when the polygrapher explains what the test will involve and how it will be given. After that, what the polygrapher does next can vary greatly depending on the situation, examiner’s personal preferences and the ‘polygraph school’ the examiner subscribes to. [vi][vii]

It’s clear the pre-test interview is far from standardized and can significantly impact how the person being examined responds to the test portion of the examination. Not only that, but the examiner can also form opinions on the persons quilt or innocence and make his judgement cased on the pre-test interview only.

As a point of reference, I once had a polygraph in which I lied to the examiner in the pre-test interview and instead told him what he wanted too here. I passed the test because he said and I quote, “I believe you are telling the truth because you came in here and told me the truth before we even did the test.” And on another occasion, I took a polygraph and told the truth in the pre-test interview and failed because the interviewer had formed the opinion I was lying.

The second stage is when the person being questioned is hooked up to the polygraph machine and is asked a series of questions. Most CQT polygraphers use three types of questions. There are relevant questions, irrelevant questions, and comparison questions. The relevant questions pertain to the crime being investigated. The irrelevant questions are in no way related to crime and could be as simple as asking the persons name or if they are sitting in a chair. The irrelevant question are questions to test the subject’s moral character. Often, they’re called probable-lie questions. They are asked in a way to prompt the subject being questioned to answer them with “no”. [viii]

The number of questions asked, and the order is usually left up to the polygrapher and the school he subscribes to. [ix] Most CQT polygraphers won’t tell the subject if their reactions indicate deception at this stage. Except, there have been reports where this has been done to pressure suspects into confessing to the crime. [x]

The third stage is where the data gathered by the polygraph is evaluated.

Most of the time it’s up to the polygrapher to determine which questions the subject was lying, being honest or inconclusive on and if the overall impression is the subject indicates guilt and lying or innocence and honesty. The polygrapher assigns a score to each answer to come up with a total score.

There are several computerized scoring systems that are supposed to keep the examiners bias out of the scoring of the subject’s test, but they have shown modest accuracy at best. [xi]

Let’s talk about the accuracy of these test. Estimates range from 59% to 89%. [xii] The National Research Council did a study that stated the accuracy was ‘Well above chance, though well below perfection’. I don’t know about you, but that range seems incredibly wide to be well above chance in my opinion.

Most psychologists and other scientists agree that there is little basis for the validity of polygraph tests. Courts, including the United States Supreme Court have repeatedly rejected the use of polygraph evidence because of its unreliability. However, the United States Supreme Court leaves the question of the admissibility of lie detector test evidence up to individual jurisdictions. Some courts allow lie detector evidence in certain proceedings or only when both parties agree to its admissibility. Other jurisdictions do not allow any lie detector evidence.

The states that sometimes allow polygraph tests as evidence in criminal case include Alabama, Arizona, Arkansas, California, Delaware, Georgia, Idaho, Indiana, Iowa, Kansas, Nevada, New Jersey, New Mexico, North Dakota, Ohio, Utah, Washington, and Wyoming.

This makes no sense to me since the Supreme Court has stated that there is no reliable scientific evidence about the accuracy of lie detector tests. They even cited Dr. Saxe’s research.

In my opinion, no one in their right mind should ever take a polygraph test. The problem is that if your convicted of a sex offense, in some states you’re forced to take one.

[i] https://www.apa.org/research/action/polygraph [ii] Saxe, L. (1991). Lying: Thoughts of an applied social psychologist. American Psychologist, 46(4): 409-15. [iii] https://www.tandfonline.com/doi/full/10.1080/23744006.2015.1060080 [iv] Telling Lies: Clues to Deceit in the Marketplace, Politics, and Marriage by Paul Ekman [v] (Raskin & Honts, 1987; Wilcox & Madsen, 2009) [vi] (American Polygraph Association, 1997) [vii] Reviewing Crime Psychology by David Canter (Editor), Donna Youngs (Editor) Page 58 [viii] Raskin, D. C., Kircher, J. C., Horowitz, S. W., & Honts, C. R. (1989). Recent laboratory and field research on polygraph techniques. In J. C. Yuille (Ed.), Credibility Assessment (pp. 1–24). Deventer, the Netherlands: Kluwer. [ix] en-Shakhar, G. (1991). Clinical judgment and decision-making in CQT-polygraphy. Integrative Physiological and Behavioral Science, 26(3), 232–240. doi:10.1007/BF02912515 [Crossref], [PubMed], [Google Scholar] [x] Iacono, W. G. (1991). Can we determine the accuracy of polygraph tests. Advances in Psychophysiology, 4, 201–207. [xi] Dollins, A., Krapohl, D., & Dutton, D. (2000, August). Comparison of computer programs designed to evaluate psychophysiological detection of deception examinations. In Psychophysiology (Vol. 37, pp. S19–S19). Department of Defense, Fort Jackson, SC: Polygraph [xii] Grubin, D. (2010). The polygraph and forensic psychiatry. Journal of American Academic Psychiatry Law, 38, 446–451. [PubMed], [Web of Science ®], [Google Scholar]