A polygraph exam is an effective way of assessing someone’s behavior. It can determine if someone is being deceptive and hiding the truth. However, polygraphs aren’t inflatable machines, and several factors could influence the results swinging one way or the other.

Most experts agree polygraph devices have an approximate accuracy of 97%, but that still leaves room for error. The outcome of a polygraph could determine a person’s future and severely impact their career, livelihood, or even their freedom. So, it’s important to understand what factors might cause an adverse result.

This post unpacks 9 elements that can affect the outcome of a lie detector test. We’ll look at each of them and explain why they might influence the result and the likelihood that they’ll result in a problematic outcome.


Understanding the Polygraph Device & Your Nervous System

Before we start, let’s break down the aspects of the polygraph device and how it interacts with the nervous system to determine deceptive behavior. By understanding these two areas in detail, we’ll get a better idea of how the other elements could affect the outcome of the exam and what we can do about it.

The polygraph device is a sophisticated instrument designed to pick up on physiological changes in the body. It detects shifts in blood pressure, heart rate, respiration, and skin and sweat gland activity. The instrumentation attached to the examinee assesses these changes, feeding them to a control box linked to the examiner’s laptop.

Software on the laptop calculates this feedback, presenting the data in chart format on the laptop’s screen where a qualified polygraph examiner assesses the results.

The physiological changes detected by the polygraph software show the examiner if the examinee is experiencing the activation of the “fight-or-flight” (FoF) response. The FoF is an autonomous system governed by the sympathetic nervous system, which is a part of the autonomous nervous system.

This is important to note because the ANS governs the aspects of our physiology and biology that we don’t consciously control. For instance, you don’t have to think about breathing or pumping your heart; the body does these operations for you without any conscious involvement.

We can’t control the FoF response; it’s a part of this autonomous system. So, we can’t stop the FoF from happening when we lie under pressure situations, like a polygraph exam. Even if you were to have total control over your emotions, you can’t stop the FoF from occurring.

So, when the examiner asks the examinee a question and the software shows an FoF reaction in their response, it means the examinee is displaying deceptive behavior. They’re acting out of self-preservation, hoping they don’t get caught, but this action and the body’s physiology ultimately give them away.


What Elements Affect Polygraph Outcomes?

With this concept of the FoF and its correlation to deceptive behavior in mind, we can understand the elements that might affect the outcome of a polygraph exam. Let’s look at these factors in detail.


#1 The Examiner’s Role in Polygraph Prep

Suppose an employer in the private sector experiences a theft resulting in economic loss. In that case, they have a right to implement a polygraph policy and test their staff to uncover the thief. Similar situations calling for implementing a polygraph policy include fraud, sexual misconduct, and drug abuse in the workplace.

However, when executing this policy, the employer must comply with “The Employee Polygraph Protection Act of 1988” (EPPA). To do that, they’ll need to hire an attorney for legal advice and an independent polygraph company that appoints an examiner to the case.

The examiner has a duty to the employer and their employees. They must remain impartial and not take sides. The examiner meets with the client and assesses the situation, builds a questionnaire for the exam, and ensures the employer complies with all the regulations surrounding the EPPA.

If the examiner doesn’t meet all these requirements, it could affect the outcome of the exam and potentially set the employer and themselves up for a lawsuit. For instance, the examiner must give the employer a copy of the test questions they ask in the polygraph exam.

Failing to do so could cause improper preparation by the examinee and the potential for them to fail the test. However, most examiners are professionals with plenty of training and experience, so it’s unlikely they’ll make any errors preparing the employer and their employees for the polygraph exam.


#2 The Fear of the Unknown & Your Nervous System Response

When employers tell their employees they plan on implementing a polygraph policy for the staff, it creates uncertainty in their team. Humans have a fear of the unknown. For instance, if you’ve never been shark cage diving and someone invites you out for this activity, you’ll probably feel scared of getting in the cage.

What if the great white breaks through the cage and tries to eat you? However, after you’ve done the dive and nothing goes wrong, you’ll lose this initial fear of cage diving, and you won’t feel the fear activating your fight-or-flight response the next time around.

However, if you don’t prepare properly for the polygraph exam, you don’t dampen the fear associated with the procedure. Your nervous system remains on edge, and you have the potential of your nervous system to launch the FoF, even if you have nothing to hide.


#3 Anxiety & the Polygraph Exam

The first time you take a polygraph. You have no idea what to expect, making you nervous. You know you’re innocent of any crime or allegations, but you still feel a sense of anxiety stepping into the polygraph exam room.

That’s entirely normal. However, some people can’t manage their FoF as well as others because they’re naturally anxious. Everyone’s different, and we can’t expect two people to behave the same. If someone has an anxiety disorder and they experience the examiner asking them a question, their body may accidentally launch the FoF, even though they don’t have anything to hide.

As a result, the examiner picks up this activity, flagging it as deception. However, like the previous example, the examiner is a trained professional. Their skills and the software can tell the difference between someone’s nervous and deceptive behavior.


#4 Polygraph Exam Preparation

One of the best ways to eliminate the fear of the unknown, of dampening its effects, is to gain knowledge of it. Moving back to our cage diving example. If you watched videos of cage diving the day before the event and spoke to people with experience with it, you’ll find you aren’t as nervous when you get in the water.

The reason is that you have a theoretical understanding of what to expect. You know there’s next to no chance of the shark getting in the cage or something bad happening. Sure, you’ll still feel a thrill, but it likely won’t be the same rampant fear you would experience if you had no understanding of the dive.

It’s the same thing with the polygraph exam. By preparing for the exam and reviewing material on what to expect, you increase your knowledge of the process and dampen your fear. The examiner expects you to do this, and they actively encourage it. By preparing properly, there’s less chance of you being overly nervous, resulting in a lower potential for an incorrect outcome.


#5 Your Routine & Sleep

It’s hard to fall asleep the night before a polygraph exam. You have a million things running through your mind. What if the boss finds out you go home and crack six beers every night before bed. Will they think you’re an alcoholic? How will that reflect on your reputation at the office?

Getting to sleep is hard when stress rampages through our body and mind. Unfortunately, not getting a good night’s sleep is a stressor in itself. The brain clears neural pathways of toxins at night, and that’s why you wake up feeling hazy when you don’t have a good night’s sleep.

This mental state places the SNS and the FoF on alert. These biological systems know you’re slower than usual, and there’s a chance you might not see a threat coming. So, you’re behind the eight-ball and at a higher chance of being overly anxious in the exam room, causing activation of the FoF and affecting the test outcome.

Listening to a guided meditation before going to bed is a good idea. This exercise clears your mind, and you’ll find it easier to fall asleep.


#6 Your Diet & Habits

What you eat and your habits also have an effect on the nervous system and your anxiety levels. If your diet consists of processed foods and lots of refined carbohydrates, your blood sugar is elevated and ramps up the nervous system response.

Drinking too much caffeine on the morning of your exam is another bad idea. Caffeine in coffee, tea, and energy drinks acts as a nervous system stimulant. It’s fine if you have a cup of coffee, but stick to your normal routine and don’t overdo it.

Drinking too much of it overstimulates the nervous system, priming the SNS and the FoF. Caffeine has an eight-hour half-life, so that means if you have too much in the morning, its effects last well into the afternoon.

Eat a sensible meal the night before the test and have your normal breakfast. Perhaps you should miss that trip to Starbucks if you feel tired and groggy. Don’t use sleep medication or supplements the night before the exam if you have no experience with them.

These drugs and supplements can leave you feeling groggy the next day and affect the nervous system and the exam outcome.


#7 Trying to Fool the Polygraph & Examiner

Countermeasures describe strategies examinees use to try and fool the polygraph device and the examiner. They come in three categories – physical, informational, and drug-based. We mentioned that it’s a good idea to research the polygraph exam to get an understanding of it before your test.

However, researching ways to beat a lie detector test before taking the exam is not a good idea. The examiner might ask if you looked up information on how to cheat the test, and then what will you say?

Looking up how to beat the polygraph is a type of “informational” countermeasure, and examiners take it seriously – it means you must have something to hide. There are plenty of physical countermeasures as well, with curling your toes while you answer a question being a popular one people like to try if they have to lie.

However, the examiner has training on how to spot these countermeasures, and they’ll likely catch you out. If you’re caught using a countermeasure, it’s an automatic fail on your polygraph exam.


#8 Using Medication During the Exam

Drug-based countermeasures are another popular strategy for people looking to hide something in a polygraph exam. Drugs like Xanax and beta-blockers have a powerful effect on the nervous system, relieving feelings of anxiety.

So, if that’s the case, they must work on the polygraph exam too, right? Wrong. The examiner and software know how to spot if you’re using these drugs, and you’ll fail the exam if they catch you.

The only time it’s permissible for you to use these drugs during a polygraph is if you have a prescription for them. In these cases, you’ll have to tell the examiner about your prescription and when you last took the drug before you undertake the test.


#9 The Examiners Experience

The examiner’s experience plays a central role in the polygraph testing process. If the examiner is fresh out of their internship and has little experience in conducting polygraph exams, they might compromise the results.

The examiner might misinterpret someone being nervous or displaying deceptive behavior. Or, they might not have the experience to assess when the examinee uses a countermeasure and let it slip undetected.

However, most examiners undergo extensive training and coaching before conducting a lie detector test themselves. These individuals may also show the test results to their colleagues if they are uncertain if they got it right.


Uncover the Truth with a Professional Lie Detector Test – Our Carefully Vetted Examiners Ensure Your Peace of Mind.