The polygraph is a complex piece of equipment. It requires a trained and experienced examiner to operate the system. The average person looking at a polygraph chart won’t know what to look for, so how do examiners identify deception in a lie detector test?

What is the examiner looking for during the session and post-exam? Let’s look at the specifics of the polygraph device, how it operates, and what data it collects for the examiner. We’ll unpack examiner training and how they learn to interpret the charts and read the examinee.


How Do Polygraph Examiners Train & Qualify for Their Job?

Polygraph examiners undergo extensive training for their careers. They start by taking subjects like math, biology, and English in high school, moving on to university, where they study criminology and criminal psychology.

After four years of study and receiving a BSc, they graduate and move on to polygraph school. Polygraph school is where they first come into contact with the lie detector machine, learn how to conduct a polygraph test, and interpret data from the device during and after the exam.

Depending on the organization, polygraph school usually lasts 18 months to 2 years. The examiner must train at an institution recognized by the American Polygraph Association (APA). The APA regulates the curriculum taught at polygraph schools, ensuring the examiner learns the right way to launch a test, employee rights in lie detector exams, and a code of ethics to remove bias when analyzing test results.

After graduating from polygraph school, the examiner joins an accredited polygraph company. They’ll undergo an internship with the company lasting anywhere from 18 months to two years, assisting the examiner in analyzing test data.

Only after finishing their internship does the examiner get to conduct polygraph exams themselves.


How Do Polygraph Examiners Evaluate Test Data?

Polygraph examiners learn the ropes of how to operate the lie detector instrumentation and software while attending polygraph school. Their training teaches them how to identify the “fight-or-flight” response (FoF) in the examinee, which they use to detect deception during the test.


Understanding the Fight-or-Flight Response

So, what is the FoF? When we experience stress, it activates the “Sympathetic Nervous System” (SNS. The SNS is part of the Peripheral Nervous System (PNS) and a component of the Autonomic Nervous System (ANS), which controls the SNS and the “Parasympathetic Nervous System” (PSNS).

The primary function of the SNS is to control the FoF response. When we experience stress, it elevates levels of the stress hormone cortisol in our bloodstream. The more cortisol you have in your system, the more stressed you feel.

People with cortisol imbalances usually suffer from stress-related disorders. They find it challenging to sleep and are prone to developing anxiety disorders. The SNS utilizes biological chemicals and hormones, like cortisol, to launch the FoF.

When we experience a stimulus in our environment that launches the FoF, our blood pressure, heart rate, and respiration increase. Our skin goes through electrical changes, and the sweat glands start perspiring. Essentially, the FoF is priming the body to flee or face a threat.

The stress involved with sitting in the exam room and taking a lie detector test primes the SNS and FoF. When the examiner asks a question and the examinee has to lie, it activates the FoF. The vital signs go wild, and the examiner notices these changes on the charts they monitor on their laptop screen via the software running on the machine.

The FoF is an “automated” response by the SNS. That means we can’t control it. The ANS controls parts of our body that don’t require conscious thought to operate. For instance, you can’t control your liver function as it filters toxins from your bloodstream.

It’s the same for the FoF; you can’t stop it when it kicks in. Some people that know about the FoF and its role in deception detection might try to control their breath, but that’s not going to make a difference to heart rate and the other vital signs monitored by the examiner.


Polygraph Instrumentation and Software

The polygraph instrumentation connects to a control box which plugs into the laptop, feeding data to the software program monitored by the examiner. The instrumentation involves two convoluted corrugated rubber tubes strapped to the examinee’s chest and abdomen.

The examiner attaches three sensors to the examinee’s fingertips, and sometimes, the examinee will sit on a pad that detects motion during the test. The instruments monitor the changes in the examinee’s vital signs as the examiner asks them questions, providing feedback to the software.

When the examiner conducts the test, they monitor each vital sign on an independent chart on their screen. The system notifies the examiner when it detects a fluctuation in vital signs that might present possible deception by the examinee.


Detecting Deception

The FoF creates massive changes in the examinee’s vital signs immediately. When the examiner asks a question and the examinee has to lie, they feel all their vital signs instantly elevate. If the examiner thinks the examinee is acting deceptively, they’ll repeat the question to see if it creates the same response.

If the examinee continually displays activation of the FoF to a particular question, the examiner may decide to pause the test. They’ll ask the examinee if anything might be causing the response. This strategy gives the examinee a chance to bring up anything they might be afraid of admitting that’s irrelevant to the question.

For example, if the examinee has a history of drug abuse but is clean now, they might tell the examiner of their experience and that they haven’t touched drugs in the last five years. The examiner will rephrase the question to leave out their history and see if it makes any difference to the test result.


Post-Exam Analysis

If the examiner detects deception, they won’t tell the examinee. They won’t divulge any speculative answer of how the examinee performed on the test after the polygraph exam. They thank the examinee for participating, disconnecting them from the instrumentation and escorting them out of the room.

The examiner returns the test data to their office, where they conduct the post-exam analysis. This phase involves the examiner reviewing the test results to determine the final verdict of the polygraph exam and whether the examinee is displaying deception.


Video Recording and Body Language Analysis

During the preliminary exam, the examiner doesn’t watch the examinee; they focus on the charts as they ask questions. However, they’ll video record the session and review the footage during the post-exam analysis.

The video recording gives the examiner insight into the examinee’s body language during the test. We all give off subtle subconscious cues when we lie. Some people might elevate the corners of their mouths or drop their shoulders when they lie.

Like the automatic responses created in our vital signs, we’re unaware of these movements, but they are easier to control if the examinee knows about them. However, your average employee won’t know they’re making these motions.

It’s also one of the reasons why the examiner will make the examinee sit on a motion-detection pad. We’ll unconsciously shift around when we feel nervous under stress created by the FoF. The pad detects these movements and registers them on the examiner’s software.

The examiner confirms this behavior during the post-exam analysis. They’ll look for body language confirming what they saw on the charts. If they see what they’re looking for, it confirms their suspicions that the examiner is acting deceptively.


Referring with Colleagues

In some cases, the examiner might be inexperienced. They might be fresh from their internship, and this is one of the first polygraph exams they conduct in the real world environment. If that’s the case, they might have suspicions of the examinee acting deceptively, but they aren’t confident in their analysis.

To clear up their analysis, the examiner refers to their colleagues. They’ll speak with a mentor with vast experience in the field and thousands of polygraph exams under their belt. The experienced examiner provides valuable insight into the other’s post-analysis, confirming or dismissing their suspicions.


Are Polygraph Exams Accurate?

Leonard Keeler changed the game in polygraph science in 1925 with his invention, the “Emotograph.” It was a commercial success and underwent plenty of development in the coming 60 years. Several models of “Keeler” polygraphs were produced by the “Associated Research” company of Chicago following Keeler’s death in 1949.

However, all of these devices involved electro-mechanical operation. As a result, the average accuracy of polygraph results was anywhere from 60% to 70%, depending on the examinee’s response to the test stimulus and the examiner’s skill at interpreting the data.

During the 1990s, we saw the introduction of software and computerized systems to polygraph devices. The results dramatically improved the accuracy of polygraph results. The American Polygraph Association (APA) states that modern polygraph systems running software tools have an accuracy rate of 87%.

However, the software developers state that their products have an accuracy of up to 89%. The point is that software brought huge advancements to polygraph science. While the detractors of the technology claim the device is inaccurate, the reality is that in the hands of a skilled examiner, it’s highly accurate at detecting deception.

A qualified, experienced, and professional polygraph examiner knows how to read the software and determine if the examinee is being deceptive in their answers. They can tell the difference between an examinee that’s nervous and one that’s displaying deceptive behavior.


Can You Fool the Examiner in a Polygraph Test?

So, can you fool the examiner and the polygraph software during the lie detector test? During the early rollout of the polygraph in the 1930s, there were plenty of reports of inaccuracies. However, when it reached use in the intelligence community for national security investigations, many clever criminals learned how to game the polygraph machine.

We saw the introduction of “countermeasures” by examinees in an attempt to fool the polygraph and the examiner during the test. Countermeasures are tactics deployed by the examiner before or during the polygraph exam.

For instance, we’ve already talked about controlling breathing. Other physical countermeasures include actions like curling the toes, clenching the thigh muscles, or biting the inside of the cheek before responding to a question.

These countermeasures supposedly interfere with the body’s ability to launch the FoF response. As a result, it creates an inconclusive result with the polygraph. Other examples of countermeasures would be thinking a terrible thought as you answer the examiner’s questions.

The issue with these countermeasures is that they all come from an era when the Keeler polygraph was the dominant machine used in lie detector tests. The newer software systems have the ability to see through these attempts to game the system.

A popular modern countermeasure involves the use of anti-anxiety medications like beta-blockers and anti-anxiety drugs during the exam. These drugs suppress anxiety and stress in the body, supposedly interfering with its ability to launch the FoF.

However, a talented examiner knows what to look for in these circumstances. If they catch you using physical or drug-based countermeasures during the exam, it constitutes an immediate failure of the polygraph.


Will Polygraph Examiners Be Replaced by AI Systems?

2023 saw the introduction of Artificial Intelligence to the world. The Open.AI service, ChatGPT, showed the public the potential of what AI has to offer. One of the biggest concerns with the advancement of AI is its ability to make many jobs redundant. So, will AI do away with the need for polygraph examiners?

What people don’t know is that AI-based polygraph systems are already in use around the world. The US, EU, and Canada collaborated on an AI-based polygraph system called “AVATAR.” They launched AVATAR in 2016 in US Border Patrol and Customs operations.

AVATAR is so advanced that it can run polygraph exams on migrants entering the country without needing human interaction to operate it. AVATAR can detect deception with an accuracy rate of 60% to 85%.

The system can also detect the use of countermeasures in the examinee. So, will AVATAR or similar AI-based polygraph systems replace the need for examiners? Well, not right now. If AVATAR detects deception, it sends the examinee to a human for further interrogation. So, the examiner’s job is safe for now.