The Truth about Lie Detector Tests and How You Can Beat One

Most of us believe that lie detector tests can identify whenever we are lying, but research shows that there’s a way to beat it.
Kashyap Vyas
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The polygraph machine that wires up your body with sensors is meant to aid in figuring out if you’re lying. Lie detector systems have evolved from recording the subject’s physiological responses on a rotating drum of smoke paper to modern laptops with automatic scoring and MRI (Magnetic Resonance Imaging) capabilities.

Despite the modernization of these truth-seeking systems, scientists believe that lie detector tests have very little (some experts say 'none') scientific basis. The accuracy of these tests has always been under the speculation and evidence-based on polygraphs aren’t even allowed in criminal court in the US and most of Europe.

Lie detector tests remained in public consciousness despite these issues largely due to its use in courtroom TV dramas and movies. However, such tests are still used most often to screen job applicants and used while interrogating criminal suspects.


The major flaw is that these tests are completely based on a person’s physiological responses, which scientists believe isn’t necessarily linked with lying. This basis poses a great risk of honest people generating false-positive results. Besides, lie detector tests can also be influenced by drugs or medical conditions, which is why a screening and drug test is a pre-requisite. But, beating a lie detector test isn’t that difficult if you manage well to understand how the system works.

How do Lie Detectors work?

The core concept behind lie detector systems is that our body betrays us when we lie. The body undergoes several physiological changes when we lie. We feel uncomfortable as our blood pressure, pulse rate and respiration behavior changes that result in visual cues and those form the base of the polygraph tests. Also known as psychophysiological detection of deception, lie detectors consist of medical devices that measure the person’s physiological behavior in response to a set of questions that are specially designed to increase stress levels.

But the test isn’t just restricted to hooking a person up with the polygraph machine. It actually starts right from the moment a person enters the test center, where a skilled tester will immediately start observing non-verbal cues that reflect whether the person is lying. Once the test starts, the machine will start recording the blood pressure, pulse rate, and perspiration. The examiner will initially ask a combination of relevant and irrelevant questions, known as “control questions”, to establish the base rate of activity. The theory behind control questions is to identify “white lies” to establish the base “lie” and “truth” readings. The baseline obtained will then be compared with the results obtained from the actual questions related to the interrogation.

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How Can You Beat A Lie Detector Test?

Spoofing a lie detector test is tricky but still possible. The loopholes present within the lie detection systems have been widely discussed and you may find different ways to trick the system over the internet. However, not all ideas are effective. The widely proclaimed methods of biting your tongue or pinpricking yourself to increase the stress levels, heart rate, and sweating while telling the truth cannot counterbalance the lies. The concept of imagining happy thoughts while lying and stressful ones while telling the truth cannot stop the machine from detecting the lies either.

So what is the best way to outsmart the lie detector test?

According to Dr. Anne Helmenstine, a Ph.D. in biomedical sciences, there are two best ways to beat the test – get completely into Zen Mode or remained stressed throughout the test.

The problem with a lie detector test is that most people become nervous even if they are not lying. But such nervous responses will not be able to fool the system. Beating the test will require more efforts and the best way you can do that is to stay upset or confused throughout the test. And, you can do this by trying to constantly remember your worst experience, solving the most difficult math problems or remember something that can keep you in stress constantly.

One of the important aspects to trick the test is to identify the questions whether they are relevant, irrelevant or the control ones. 'Hold your horses' and understand the question type. Irrelevant questions are of a nature that has nothing to do with the interrogation; questions such as “What is your name?” or “Are you a resident of (city)?” While relevant questions such as “Where you present on the crime scene?” are important ones. Control questions are “yes”, “no” types where mostly the answer should be “yes” instead of the white lies. The questions in this category are usually recognizable, such as “Have you ever stolen something?” or “Have you ever lied to anyone? ”

Another hint: try to give answers in “yes” or “no” wherever possible and answer it without hesitation. Remember not to fall for an accusation. Instead, you can use it to increase your feeling of being upset and confused. It is also important to control your breathing and know how you react to each question by asking someone to ask the questions that you are likely to encounter during interrogation.

Beware that the examiner is not your friend but a skillful person in psychology who is there to record every single response to get the truth out. The best way is to play dumb rather than trying to impress the examiner that you’ve come completely prepared.

While it may sound fascinating to try and invalidate the lie detector test, it looks good only in Hollywood thrillers rather than experiencing it first-hand. We hope that you have never been in a situation where you require taking a lie detector test. And even if you happen to take one, the easiest way out is to remain honest.