How to Get the Most Accurate Polygraph Result

Polygraph machines are often referred to as ‘lie detectors.’ However, despite this popular nickname, they do not detect lies! What they do is help the polygraph examiner to detect specific behaviors that are usually exhibited during psychological threats – which includes lying. An experienced polygraph examiner can often predict the outcome of an exam before examining the results because they are trained to read body language and other behaviors.

One of the most common fears people have when it comes to taking a polygraph exam is that it will somehow cause them to fail even although they are telling the truth! This can be a particular worry if the exam is part of an employment screening process or is for litigation purposes. The chances of getting a false positive on a polygraph exam are incredibly slim. However, if it helps to put your mind at ease, here are a few things that will help to eliminate the possibility of a false positive.

Nerves & Anxiety

If you are feeling anxious about the polygraph, you may be worried that you will appear to be lying. This can then make you feel even more anxious, and you end up trapped in a vicious cycle. If you are suffering from a bad case of the nerves from the outset, then the readings will be consistent throughout. A baseline is taken at the beginning of the test, so if you are anxious during this, it is going to expect higher readings throughout the session, making an allowance for your nerves. The examiner will be looking for results that ratchet up or down considerably away from your baseline levels.

Drugs & Alcohol

Somewhere along the line, a myth began that certain illegal drugs could be used to help you to pass a polygraph test even if you were lying. However, this is not the case. With that being said, it is still possible for your results to be affected if you are under the influence at the time of the test. If you want an accurate result, then it is best to be free of drugs and alcohol before the test.

Comfort Levels

There are a few other factors that can help to make the process a more pleasant experience and ensure an accurate result. You will want to be as relaxed and as comfortable as possible during your exam. Try to avoid restrictive or uncomfortably tight clothing. Also, be aware that a polygraph exam can often be a lengthy process. Don’t try to squeeze it into an already busy day, as you may get overly agitated if you are worried about missing your next appointment. It is also a good idea to be well-rested so that sleep deprivation is not going to impact your readings.

Uncover the truth!


Ken Shull served as a Special Agent with the FBI for almost 25 years and was head of the FBI Polygraph program until his retirement in 2001. At that time he set up the Kendall Investigations practice as a private investigator in Knoxville, TN offering Polygraph services, private investigations, and security guards. Ken is a member of the American Polygraph Association and The American Association of Police Polygraphists.

The Truth is Still the Truth Even if No One Believes it, A Lie is Still a Lie Even if Everyone Believes it.