How to Beat a Lie Detector Test

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How to pass a lie detector test

How to pass a lie detector test – Photo credit: Lwp Kommunikáció – Flickr


The polygraph is no ordinary psychometric test. Although widely used by government agencies, especially in law enforcement and intelligence, polygraph techniques have been repeatedly discredited as pseudoscience by the scientific community.

Polygraphs are based on the simple notion that most people become physiologically ‘aroused’ in response to their own lies. The typical arousal response includes increased heart rate, respiration, blood pressure, and skin conductivity.

There’s just one problem, however. Lots of things cause the signs of physiological arousal, including exercise, apprehension, love, and lust. All of these present as the same set of symptoms, so how do you know whether a given nervous system response betrays the paranoia of the liar or the anxiety of a nervous yet innocent test-taker? That’s just it – you don’t.


Because polygraphs are notoriously unreliable tools for distinguishing between truths and falsehoods, people compelled to undergo a polygraph examination may worry they could be denied a job or unfairly red-flagged for no good reason. For these unfortunates, as well as curious bystanders, we humbly present: How to beat a lie detector test.

FYI: The government doesn’t like people teaching other people how to pass lie detector tests, probably because thousands of federal employees take them to get sensitive jobs and security clearances every year. Defying the first amendment, the feds even recently imprisoned someone for it. Therefore, do not use the following information to lie, cheat, or steal – the government doesn’t like competition.

Polygraphy 101

How do lie detectors work? It’s not so much about the device as the questions and how you respond to them. Technically, a lie detector test measures the difference between your level of physical arousal when you are probably lying and the level when you are supposedly telling the truth. A series of questions are used to gather the data for comparison.

According to polygraph theory, a liar will have a stronger reaction to questions invoking their supposed crimes, at least compared to more generalized, although topically related questions. An innocent, on the other hand, should have a stronger reaction to generalized control questions than to relevant ones. Hint: That’s your first clue for how to beat a lie detector test.

Know Your Questions

There are three types of questions on the common “Modified General Questions Test” (MGQT) lie detector test: Comparison/control questions, relevant questions, and irrelevant questions.

Control Questions

Your polygrapher will lie to you as part of the test. The first lie is that you are supposed to tell the truth on all questions. In fact, however, you are expected to lie on some and to tell the truth on some. Anticipated lies serve as control or ‘comparison’ questions.

For example: Have you ever lied to get out of trouble? Most people will answer no when asked this question, simply because they don’t want to be taken as a liar.

Nevertheless, almost everyone has lied to get out of trouble at one point or another. Having lured you into fibbing, the polygrapher assumes your response is a lie. The test-taker has inadvertently provided a live baseline measurement for what one of their lies looks like on the machine.

Similar control techniques are used on professional personality tests like the MMPI. The best way to detect deception, according to some psychologists, is to get the person to lie and then measure their physiological profile.

Other Questions: Relevant and Irrelevant

Relevant questions are questions that pertain to the issue at hand, such as a crime you may or may not have committed. They are usually more narrow or topically specific because they are designed to find out if you have direct knowledge of the specified events. Relevant questions are often few in number.

Irrelevant questions are unscored. Their sole purpose is to mislead test-takers. Polygraphers will tell you these obvious, factual questions – like ‘Are the lights on in this room?’ or ‘Is your name Bob?’ – are used to determine the baseline for your truth-telling. It’s not true. Test-takers trained in countermeasures will recognize these phony controls and disregard them.

Pass a Polygraph With Jedi Mind Tricks

If you want to be taken as truthful, you’ll need to produce the physiological profile of a non-liar: relatively stressed out on control questions and cool as a cucumber on relevant ones. Ideally, you’ll exhibit a weak response to the controversial questions, even when you are lying, and a strong response to the comparison questions designed to induce a lie.

To successfully employ countermeasures, you must be able to manipulate your body’s fight-or-flight response on-demand. Most people find that quite difficult. Some tactics for inducing a stressful response when you’re not lying, for instance, include biting your tongue or thinking terrible thoughts. Find what works for you, and practice a lot beforehand.

Even if you cannot switch your responses up entirely, try to diminish the gap between your supposed truths and presumed lies to the greatest extent possible. If you can obscure the difference enough, the test will be deemed inconclusive. Some countermeasures are better than no countermeasures.

Moreover, if you fail, there’s at least no way of knowing you were trying to employ countermeasures…unless, of course, they ask you straight up and the polygraph gives you away. Whatever you decide to do, do it with unbridled confidence. Polygraphers have noted that the subject’s fundamental fear of detection – their underlying anxiety about being caught lying – is what makes polygraphs work in the first place.

Remember Your Polygrapher

There’s no such thing as a machine that can tell whether you are lying or not. There is only a machine that can measure variations in your anxiety levels, and a polygrapher who can make an educated interpretation of the data.

It’s ultimately up to your polygrapher to decide if you are telling the truth or not. So be friendly and put off good vibes. Establishing rapport with your examiner can only help your case when he or she makes a subjective evaluation of your truthfulness. Any Soviet spy worth his соль could tell you that.

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One Comment

  1. John Raymore

    John Raymore

    February 14, 2015 at 8:51 pm

    I cannot tell a lie, this is a great article!

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