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Wednesday, December 7, 2022

Can A Liar Beat the Polygraph?

     In order for a polygraph (lie detection) test result to be accurate, the instrument must be in good working order; the polygraph examiner must be properly trained and experienced in question formation and line-chart interpretation; and the subject of the test--the examinee--must be a willing participant in the process. Not  everyone is suited for polygraph testing, including people who are ill, on drugs, under the influence of alcohol, extremely obese, retarded or mentally unbalanced. (In America that's a lot of people.) Criminal suspects who are emotionally exhausted from a police interrogation do not make good polygraph subjects. Children and very old people should not be placed on the lie detector either.

     The polygraph instrument measures and records the examinee's involuntary, physiological (bodily) responses to a set of ten yes or no questions. The examinee should know in advance what he will be asked. Based upon changes in the examinee's blood pressure, heart rate, breathing patterns and galvanic skin response, the examiner will draw conclusions on whether the subject told the truth or lied. Polygraph examiners are not recognized in the criminal court system as expert witnesses, therefore polygraph results are not admissible as evidence of guilt in criminal cases.

     Congress passed a federal law in 1988 that prohibited the use of the polygraph as a private sector pre-employment screening measure. It is widely used, however, in law enforcement as an investigative tool and as a way to screen job applicants.

     Over the years, more and more local, state and federal law enforcement agencies have required job applicants to submit to polygraph tests. These law enforcement job candidates are typically asked if they've ever sold drugs, stolen significant amounts of money or merchandise from their employers or are in serious debt. Employment candidates may also be asked if they have omitted anything important from their resumes or job applications.

     In 2013, more than 73,000 Americans were either given polygraph tests as part of the federal job application process or were tested to determine if they should be allowed to keep their jobs. Federal agencies involved in national security such as the National Security Administration, the FBI and the CIA, periodically put employees on the polygraph to make sure they haven't gone rogue. Other federal agencies that require periodic screening tests include the DEA, ICE, the Secret Service, ATF and the Postal Inspection Service.

     Not everyone is a fan of the polygraph technique. Generally, there are two kinds of polygraph critic. There are the anti-polygraph people who object to this form of lie detection because they believe the instrument and the technique is junk science and therefore no more reliable than a flip of a coin. The other group objects to polygraph use because they believe the instrument is utilized to violate the privacy of those tested. Critics in this camp accuse polygraph examiners, and the people who hire them, of abusing the process by digging for dirt that is unrelated to the job application process.

     Over the years there have been numerous high-profile examples of FBI and CIA spies who avoided detection for years even though they were subjected to regular polygraph testing. Aldrich Ames, the counterintelligence CIA officer convicted of spying in 1994, must have found a way to beat the polygraph screening test. (I do not believe that suspects in criminal cases can lie to competent examiners and get away with it.) This was also true of FBI agent Robert Hanssen who was convicted of thirteen counts of espionage in 2001.

     Russell Tice, the National Security Administration whistleblower who was one of the first to leak evidence of the NSA's spying on U.S. citizens, revealed that during his 20-year career in counterintelligence, he beat the polygraph a dozen times. Mr. Tice believed that due to political correctness and lawsuits, polygraph tests have become easier to manipulate. He has said that beating the employment screening examination had actually become easy. Over the years, Mr. Tice and others have published, in print and online, instructions on how to mislead polygraph examiners.

     Polygraph examiners ask what they call relevant, irrelevant and control questions. Irrelevant questions such as "Have you ever eaten pasta?" are intended to set the baseline of a truthful response. Control questions are designed to create a baseline or point of reference for deceptive responses. To do that, polygraph examiners ask subjects questions likely to produce deceptive answers. In other words they want the subject to lie. For example: "Have you ever lied to your parents?" or "Have you ever cheated on a test?" Most subjects, when they answer "no" to these questions are lying. Relevant questions are ones that directly address the point of the polygraph examination. In a national security employee screening test an employee with access to classified information might be asked if he or she has leaked classified documents to a journalist. To determine if the subject is telling the truth about not leaking information, the polygraph examiner compares the physiological responses to the relevant query with the subject's responses to the control and irrelevant questions.

     According to those who have made it their mission to teach people how to beat the polygraph, manipulation techniques, or so-called "countermeasures," center around how the examinee should respond to the control and relevant questions. In answering a control question designed to produce a deceitful physiological baseline, the subject, while telling the expected lie, should bite his tongue. The idea here is to cause the polygraph instrument to record a strong physiological reaction to the subject's lying. When asked a relevant question the answer to which will be a lie, the subject is instructed to find a way to distance himself from the question by daydreaming, counting backward or slowing down his breathing.

     If this countermeasure works, the relatively mild responses to the relevant questions, when compared to the wild reactions to the control questions, might lead the polygraph examiner to conclude that the examinee told the truth.

     Law enforcement job applicants are better off simply telling the truth and hoping for the best. Very few people have the presence of mind and discipline to successfully employ these polygraph manipulation tricks. As for national security employees who are either spies or future whistleblowers, they have nothing to lose by trying these techniques. Notwithstanding Aldrich Ames, Robert Hanssen and Russell Tice, fooling a competent polygraph examiner is a lot easier said than done. And that is no lie.


  1. One tiny thing, NSA stands for the National Security Agency, not Administration.

  2. It is very difficult to catch a criminal. Most will try to deceive and weasel their way out of responsibility for what they have done. If the polygraph technique could catch a few or help push an investigation in the right direction, that is terrific. It means the polygraph is a good investigative aide. Of course, more is needed to effect the actual conviction.

  3. So if I have eaten pasta I say I never have eaten pasta. Then my lie registers as truth. And sets the baseline. Got it.

  4. Any Police Chief will tell you that the polygraph is nothing but a Bullying tool. There is NO SUCH THING AS A LIE DECECTOR.

  5. I have had three polygraph sessions, all for national security positions. You indicated above that the examiner is not supposed to ask a question that has not been rehearsed with the examinee. Well, all three times I was examined, the examiner asked the ten questions as indicated (in order, then randomly) then flung in another unrehearsed question. All three times. These sessions were separated by years and different examiners. This was my experience.