The first polygraph machine came to life more than a century ago. Many people still misunderstand these controversial devices. A polygraph doesn’t actually detect lies. The machine records your body’s changes that occur during a “fight, flight, or freeze” response.
The American Polygraph Association claims these tests are about 87% accurate, but scientific studies tell a different story. A key 2003 National Academy of Sciences report showed that polygraphs could identify lies only about 70% of the time. Research quality hasn’t improved much over the last several years. Polygraph users believe deceptive answers create physical responses that can be separated from truthful ones. The scientific evidence behind this idea remains weak.
A polygraph examiner watches for fight-or-flight responses as you answer specific questions. This piece explains the science behind polygraph technology and shows what physical signals these machines measure. You’ll see different testing methods and learn about why polygraphs remain both accessible to more people and highly debated in the United States. From years in the field and hundreds of real cases, this is my life’s work delivering the most up-to-date, expert-level guidance in the world
Physiological Basis of Polygraph Testing
Image Source: ScienceDirect.com
Your body’s internal regulatory mechanism—the autonomic nervous system (ANS)—powers the polygraph’s basic operation. A polygraph doesn’t read your mind. It just tracks how your body reacts when you answer questions under stress or anxiety.
Autonomic nervous system and polygraph response
Two main branches make up the autonomic nervous system that controls involuntary bodily functions. Your “fight or flight” response kicks in through the sympathetic nervous system that readies your body to act. The parasympathetic nervous system brings about a calmer “rest and digest” state. These systems work together yet independently and create physical changes that polygraphs can detect.
Your ANS might react without you even knowing it during questioning. Different neurochemical pathways trigger these responses. The sympathetic system uses norepinephrine to speed heart rate and raise blood pressure. The parasympathetic system uses acetylcholine to slow things down [1].
Polygraphs work so well because you can’t easily control these ANS responses. Each person’s autonomic activation differs. Some show mostly sympathetic increases, others show vagal withdrawal, and some display reciprocal sympathetic activation [2]. That’s why people react differently to the same polygraph questions.
Deception creates mental and emotional stress that triggers physical changes as the sympathetic nervous system activates [3]. In spite of that, this pattern isn’t the same for everyone. Some people show stronger cardiac reactions while others display greater vasomotor activity [2].
Lie detector physiological responses: heart rate, respiration, and skin conductivity
Polygraphs track three key body systems that show ANS activity:
1. Cardiovascular Activity: The device monitors your heart rate and blood pressure changes. Research on heart rate during deception shows mixed results. Some studies show increased heart rate while lying [4], but others found it decreases [4]. This might happen because sympathetic and parasympathetic nervous systems pull in opposite directions.
Stressful situations usually raise blood pressure, especially systolic pressure, as your body gets ready to handle threats. Your systolic and diastolic blood pressure might spike above normal levels when you’re not telling the truth [3].
2. Respiratory Patterns: The polygraph’s pneumographs watch both chest and belly breathing. People often breathe irregularly or hold their breath when lying [1]. This happens partly because they try too hard to stay calm, which changes their natural breathing pattern [4]. Studies prove that breathing changes stand out when comparing crime-related items to neutral ones [4].
3. Electrodermal Activity (EDA): Lab studies show EDA as the most sensitive way to detect lies [2]. It measures how your skin’s electrical properties change when you sweat. EDA stands out because sweat glands use acetylcholine instead of norepinephrine from sympathetic nerves [2].
EDA shows up in two ways—quick changes from specific triggers (phasic responses) and slower background changes over time (tonic responses) [2]. Both help evaluate polygraph results.
Medical conditions that affect the ANS can throw off polygraph results. About 60% of rheumatoid arthritis patients show weaker cardiovascular responses [1]. Common medications like beta-blockers can also change how your body reacts by reducing heart rate changes and dulling stress responses [1].
Core Polygraph Techniques Explained
Modern polygraphs use three main questioning techniques. Each technique works for specific testing scenarios and builds on different psychological principles. Let’s get into how examiners try to separate deceptive from truthful responses.
Comparison-Question Technique (CQT) structure
The Comparison Question Technique (CQT) is accessible to more people in criminal investigations than any other polygraph method. The CQT matches your body’s responses to two types of questions. You’ll face relevant questions that directly ask about what’s being investigated (e.g., “Did you steal the USD 750.00 from Jones’ office?”) and control questions that make innocent people react [5].
Control questions come in two forms. Probable-lie control questions ask about general bad behavior from your past that even honest people might lie about (“Have you ever stolen anything?”). These questions stay vague and cover long periods to make you doubt your answers [5]. The other type, directed-lie tests, tell you to answer “no” to obviously true statements like “During the first 20 years of your life, did you ever tell even one lie?” [6].
The CIT’s basic theory makes sense: innocent people react more strongly to control questions because they’re probably lying about those. Guilty people show stronger responses to relevant questions because these questions pose a bigger threat right now [1]. This creates a unique crossover pattern in body responses based on whether someone’s guilty [6].
Studies of the Utah CQT show specific decision points: scores of -4 or less point to deception, while scores of +2 or higher suggest truthfulness [7]. But a 2019 study found the CQT’s scientific foundation is nowhere near solid, and we still don’t know its true error rates after decades of use [8].
Concealed-Information Test (CIT) and guilty knowledge detection
The Concealed-Information Test (CIT), once called the Guilty Knowledge Test (GKT), works completely differently. Instead of trying to catch lies directly, it tries to find out if you know specific details that only the person who committed the crime would know [9].
The CIT asks multiple-choice questions with one true crime detail (the “key item”) hidden among several believable but wrong choices. To cite an instance, in a drowning investigation, the examiner might ask: “Was Harry stabbed? Was Harry strangled? Was Harry shot? Was Harry drowned?” [1]. The key item stands out only to guilty people, who should show stronger physical responses to it.
The CIT taps into the orienting response (OR)—our natural reaction to important stimuli. Crime-related details signal something special to perpetrators and trigger stronger ORs than other details [10]. Lab research shows that the CIT can effectively tell guilty people from innocent ones by measuring things like skin conductance, breathing, heart rate, and even P300 brain responses [10].
One study got impressive results. Their logistic regression models used skin, breathing, and heart measurements to correctly identify guilty and innocent participants more than 90% of the time [11]. But the CIT has real-world limits. The biggest problem is keeping key items secret from innocent suspects, which doesn’t work very well in today’s media environment [12].
Relevant-Irrelevant Questioning Method
The Relevant-Irrelevant Technique (RIT) is the oldest and simplest polygraph method. It compares how people respond to crime-related questions versus obvious fact questions (“Is today Friday?”) [5].
The method assumes honest people respond the same way to all questions, while liars react more strongly to relevant ones [5]. Government agencies still use a version of the RIT for pre-employment screening [13].
Federal employment screening with RIT usually asks about espionage, sabotage, unauthorized sharing of classified information, criminal activity, and lying on security forms [14]. But modern polygraph researchers call the RIT outdated because it lacks standard ways to give and score tests, making scientific evaluation tough [6].
Each technique offers a different approach to the same challenge. They all try to create conditions where your body’s responses might reveal hidden information or lies—though some work better than others based on scientific evidence.
Step-by-Step Polygraph Test Procedure
Image Source: Polygraph Detector Service
A polygraph test follows a well-laid-out process that lasts 1-3 hours based on specific needs and situations [5]. Each step helps experts interpret the collected body signals properly.
Pre-test interview and baseline fine-tuning
The examiner starts with a pre-test interview that runs between 20-90 minutes [5]. This vital step does more than just break the ice. The examiner walks you through the process, goes over the questions, and helps clear your doubts [15].
The pre-test interview aims to achieve four key things:
1.Get your background details and case information
2.Build trust and create the right mental state for testing
3.Make sure you understand all questions completely
4.Show you how the polygraph equipment works
The pre-test becomes powerful because it shapes your mental state. Smart examiners stress the test’s accuracy to help honest people relax while making deceitful ones more nervous [16]. Yes, some examiners run a “get-to-know” test where you tell a small lie on purpose, and they show you how the machine caught it [17].
Next, the examiner fine-tunes the polygraph to match your body’s unique responses and sets the machine’s sensitivity to capture your baseline reactions accurately [3]. This process creates a starting point to measure your later responses during questioning.
Question sequencing and physiological monitoring
The formal test begins after the pre-test. The examiner pumps up the blood pressure cuff and starts recording with a 10-15 second baseline check [5]. Questions come with 15-20 second gaps between them so your body can recover. The best gap should not be less than 20 seconds, though 25 seconds works better [18].
Questions follow a specific order based on the chosen test method. Most tests start with basic questions to get baseline readings before mixing in relevant and comparison questions [15]. The machine records your heart rate, breathing, and skin response all at once.
Examiners must stick to strict rules during this part. They ask questions without any emotion to avoid swaying your responses and must keep the recording quality steady [18]. The examiner also writes down any notable behaviors that might help explain the results later.
Post-test analysis and scoring
The examiner studies the recorded data carefully after collecting all readings. They check your baseline state and look for any interference that could affect the results [19].
Experts score polygraph charts using number systems with set cutoffs. For comparison question tests, they often use a 7-position numerical scale. Scores above +6 show truthfulness, below -6 point to lying, and scores in between remain unclear [20].
Scoring works by comparing how you react to relevant versus comparison questions across different body signals. Examiners look for changes in:
- Baseline levels and size of responses
- How long responses last
- Changes in breathing patterns [20]
The examiner puts their findings in a report that presents data interpretation without personal opinions [21]. Many organizations need quality checks after tests to make sure everything met professional standards [18].
The process ends with a wrap-up interview to talk about results and discuss any unusual responses [15]. These talks sometimes lead guilty people to confess, though innocent people might confess too [20].
Scientific Evaluation of Polygraph Accuracy
Image Source: Lie Detector Test
Scientists have evaluated polygraph accuracy for decades, and the results aren’t great. Research shows big limitations that make us question how reliable these tests really are. The gap between claimed and actual accuracy rates tells us we need to think about what science really shows about this controversial technology.
How accurate is a polygraph test according to peer-reviewed studies
The science behind polygraph accuracy shows mixed results. Tests in controlled environments have shown accuracy rates between 83% and 95% [4]. The numbers from independent researchers outside the polygraph community paint a different picture, with false positives that exceed 50% in some cases [4]. A newer study that looked at wrongfully convicted people’s polygraph results found unreliable conclusions about 50% to 65% of the time—this is nowhere near as good as flipping a coin [22].
The accuracy is different based on which testing technique you use. The Concealed Information Test (CIT) performs slightly better with median accuracy (0.88) compared to Comparison Question Tests (CQT) at 0.85, though statisticians don’t see this as a meaningful difference [23]. Law enforcement cases showed accuracy values from 0.711 to 0.999, with a median of 0.89 [23].
We have a long way to go, but we can build on this progress [23]. The quality of research itself raises concerns—the National Research Council looked at 194 studies and found only 57 (30%) met basic scientific standards [24].
False positives and false negatives in polygraph results
False positives happen when honest people get flagged as liars, while false negatives let liars slip through undetected. Field studies show false positive rates from 0 to 75%, averaging 19.1%, while false negative rates range from 0 to 29.4%, averaging 10.2% [2].
There’s another reason these errors happen. We tested people’s emotional states, medical conditions, and individual physiological responses that affect test results by a lot [25]. To cite an instance, about 60% of people with rheumatoid arthritis show reduced cardiovascular responses that could throw off test results [4].
The base rate problem creates a mathematical challenge. Security screening scenarios with low guilt rates (like one guilty person among 1,000 employees) show that even with 95% validity, a polygraph would catch the guilty person but also wrongly flag 50 innocent people [2]. Even at 99% validity, you’d still get 10 false positives for each correct catch [2].
National Academy of Sciences findings on polygraph reliability
The 2003 National Academy of Sciences (NAS) report made several key points about polygraph reliability:
- The scientific foundation is “weak” with research of “low quality” [26]
- Polygraphs work better than chance at catching lies, but nobody knows the real error rate [26]
- These tests are “far from perfect” and don’t work well for security screening [8]
- Tests lose accuracy when used for screening instead of investigating specific incidents [8]
- Making tests sensitive enough to catch most violators means many innocent people will fail [8]
The NAS report warned that “national security is too important to be left to such a blunt instrument” [8]. Over the last several years, a 2019 review found minimal improvement in research quality, and the report’s conclusions still hold up [26].
The accuracy rates from controlled lab tests probably look better than real-world results [23]. This happens because people in labs don’t have the same motivations as those taking actual polygraph tests [23]. The basic idea that lying always causes specific physical responses we can measure reliably still lacks scientific proof [8].
Countermeasures and Test Manipulation Tactics
Polygraph accuracy has a major weakness: countermeasures—techniques people consider to manipulate test results. These strategies range from basic physical actions to complex psychological methods that distort physiological responses during testing.
General state countermeasures: relaxation and rapport
You can use general state countermeasures to affect your physiological state throughout the test. A relaxed or consistently agitated state creates an unusual baseline that makes interpretation difficult. Your baseline stress level rises when you recall traumatic memories or solve complex math problems mentally. Some people try deep relaxation techniques to minimize their reactions. Building rapport with the examiner before testing helps reduce anxiety. Polygraph tests often make people feel emotions from fear to frustration [27].
Specific point countermeasures: pain, breathing control, and mental tricks
Specific point countermeasures target individual questions instead of your overall state. Physical tactics work when you press your toes against the floor, bite your tongue, tense muscles, or contract your sphincter muscle during control questions [6]. These actions create false physiological responses that skew results. Lab studies show these techniques reduced detection rates from 80% to 10% in concealed information tests [28].
Breathing manipulation stands out as one of the most common countermeasures. Small changes in breathing patterns influence other physiological channels [7]. Mental countermeasures help when you visualize stressful scenarios during control questions to increase responses. This makes relevant question responses look normal in comparison [29].
Why trained individuals can beat the polygraph
Random countermeasures usually fail—48% of subjects try them, but guilty individuals rarely succeed [7]. Proper training in countermeasures can reduce detection accuracy dramatically. Studies reveal false negative rates increase to 47% after training with feedback [6], and reach 70% with higher motivation [6].
Examiners find it hard to spot countermeasure use. Their detection attempts lead to many false positive errors [7]. Even experienced polygraphers cannot separate countermeasures from normal physiological patterns [7]. Truth-telling subjects who try countermeasures often make things worse. They increase their chances of being labeled deceptive [7].
Legal and Institutional Use of Polygraphs
Polygraphs serve as tools in government sectors of all types, especially where special exemptions permit their use.
Use in U.S. law enforcement and intelligence agencies
Federal agencies use polygraph examinations extensively. About 70,000 people take these tests each year when they apply for security clearances and federal jobs [30]. The Intelligence Community (IC) uses three types of polygraph examinations: Counterintelligence Scope Polygraph (CSP), Expanded Scope Polygraph (ESP), and Specific Issue Polygraph (SIP) examinations [31]. The FBI now conducts polygraph tests to find information leak sources within the bureau [32].
Employment screening and the Employee Polygraph Protection Act
The Employee Polygraph Protection Act (EPPA) of 1988 transformed how private companies use polygraphs. This law prevents most private employers from making employees or job candidates take lie detector tests [33]. The law has specific exemptions for:
- Security service firms (armored car, alarm, and guard companies) [33]
- Pharmaceutical manufacturers, distributors, and dispensers [33]
- Workplace incident investigations that involve economic loss [33]
Federal, state, and local government employers remain exempt from these restrictions completely [33].
Admissibility in court: state-by-state differences
Less than half of U.S. states accept polygraph evidence in criminal trials [9]. About 25 states allow polygraph tests as evidence, but most require both parties to agree to the examination beforehand [12]. The United States Code and Federal Rules of Evidence have no specific rules about polygraph admissibility [34]. Judges can allow polygraph results only under special circumstances [34].
Author’s Notes: Mastering the Mechanics of Truth Verification
As the author of this series, I want to provide you with a high-level strategic summary that bridges the gap between the technical process and the real-world implications of polygraph testing. These notes serve as an essential extension of our core content, offering a professional perspective on how to navigate the complexities of lie detection with clarity and purpose.
The Structural Framework of the Exam
The Four-Phase Architecture: Every professional exam is built on four distinct pillars: the Initial Interrogation, the Pre-test Phase, the In-test (Polygraph Exam), and the Post-test Analysis.
The Foundational Record: Phases one and two (Interrogation and Pre-test) are critical; they serve as the foundational record of your verbal and non-verbal behavior patterns, which the examiner uses to distinguish between honest responses and deceptive indicators.
Question Volume and Format: Expect a focused session involving typically 10 to 20 questions. These are strictly formatted as “Yes” or “No” to eliminate ambiguity and ensure a clear physiological response.
Physiological Monitoring and Indicators
The Science of Deceit: The polygraph does not “read minds”; it measures specific physiological spikes associated with the stress of lying.
Primary Metrics: Examiners monitor four key indicators: blood pressure, heart rate, breathing rate, and—most importantly—skin conductivity (sweat gland activity).
Indicator Scrutiny: During the post-test analysis, the examiner specifically looks for scientific patterns associated with deception rather than general nervous stress.
Navigating Psychological and Tactical Nuances
Accuracy Demonstrations: Be prepared for the examiner to perform a demonstration of the machine’s accuracy. This is a tactical move designed to make an examinee feel uncomfortable with the idea of lying.
Case-Specific Depth: You will be asked about more than just the facts of the case. Expect inquiries into your feelings about potential punishments and any personal suspicions you hold regarding the investigation.
Baseline Establishment: Before the real questions begin, the examiner will use “Control Questions” (e.g., “Have you ever stolen anything?”) to elicit a known physiological response for comparison.
Strategic Considerations and Consequences
The Margin for Error: It is vital to acknowledge the limitations of the technology. “False Positives” can unfairly damage reputations or cost job opportunities, while “False Negatives” allow guilty individuals to avoid accountability.
The Right to Feedback: Once a determination is made, you are entitled to a feedback session. This is your actionable opportunity to explain any physiological discrepancies found in the charts, such as reactions caused by health conditions or high anxiety.
Contexts of Use: This technology remains a standard tool for law enforcement, national security, and high-level employment screening for intelligence and government personnel.
Final Takeaway
Understanding the rationale behind the polygraph—and its inherent limitations—empowers you to make educated choices. Whether you are undergoing a test for a sensitive position or a criminal investigation, approaching the process with transparency and a clear understanding of your rights is your best strategy for a successful outcome.
Conclusion
Polygraphs are both fascinating and controversial tools in the world of truth verification. You might be surprised to learn these devices don’t actually catch lies – they just measure how your body reacts to stress and anxiety. Law enforcement and intelligence agencies use them a lot, but the science behind their reliability isn’t very solid.
The biggest problem is the gap between claimed success rates and what science tells us. Supporters say these tests are right 90% of the time, but independent scientific studies, like the groundbreaking National Academy of Sciences report, paint a very different picture. This explains why U.S. courts rarely accept polygraph results.
The way your body responds during polygraph tests can clarify how they spot deception in specific situations. Your nervous system reacts to stress without you controlling it, but these reactions vary greatly from person to person. That’s why using the same interpretation method for everyone leads to both false positives and negatives.
On top of that, it doesn’t help that people can learn to beat these tests. Someone with the right training can control their body’s responses by using specific techniques to manage their breathing, muscle tension, or mental state during questioning.
The technical stuff aside, using polygraphs brings up serious questions about privacy rights and using imperfect tools to make important decisions. In spite of that, these tests still have their place in special situations where other verification methods are just as challenging.
The future might not belong to traditional polygraphs but to advanced brain scanning methods like fMRI or EEG. These technologies could give us a direct window into what happens in the brain during deception, rather than just measuring how the body reacts. Unlike polygraphs that look at the effects of lying, these brain scans focus on the root cause – the actual patterns in your brain when you hide information or make up stories.
Movies and TV shows might make polygraphs look like perfect lie detectors, but they’re actually where psychology, physiology, and technology all meet. The fact that we keep using them despite what science says shows how badly humans want to be sure about truth – something that stays out of reach even with all our tech advances. Note that if you ever face a polygraph test, you should understand both what it can and can’t do.
Key Takeaways
Understanding how polygraphs actually work reveals both their capabilities and significant limitations as truth-detection tools.
• Polygraphs don’t detect lies directly – they measure physiological stress responses like heart rate, breathing, and skin conductivity through your autonomic nervous system
• Scientific accuracy is questionable – independent studies show 50-65% unreliability rates, contradicting the 87% accuracy claims by polygraph associations
• Countermeasures can beat the test – trained individuals using breathing control, muscle tension, or mental tricks reduce detection rates from 80% to just 10%
• Legal admissibility is limited – fewer than half of U.S. states allow polygraph evidence in court, and federal employment screening remains the primary use case
• False positives are a major problem – even with 95% accuracy, screening 1,000 people would correctly identify one guilty person but falsely flag 50 innocent individuals
The National Academy of Sciences concluded that polygraphs are “far from perfect” with a “weak” scientific foundation, making them unreliable for high-stakes security screening despite their continued institutional use.
FAQs
Q1. How accurate are polygraph tests? While polygraph proponents claim accuracy rates around 90%, independent scientific studies show much lower reliability. Research indicates polygraphs may be unreliable in 50-65% of cases, performing only slightly better than chance in some scenarios.
Q2. What physiological responses does a polygraph measure? Polygraphs typically measure three main physiological responses: cardiovascular activity (heart rate and blood pressure), respiratory patterns, and electrodermal activity (skin conductivity). These are believed to indicate stress or anxiety potentially associated with deception.
Q3. Can polygraph tests be beaten? Yes, trained individuals can potentially beat polygraph tests using various countermeasures. These include physical tactics like controlled breathing or muscle tensing, as well as mental techniques such as visualizing stressful scenarios during control questions. Studies show these methods can significantly reduce detection rates.
Q4. Are polygraph results admissible in court? The admissibility of polygraph evidence varies by jurisdiction. Currently, fewer than half of U.S. states allow polygraph evidence in criminal trials. In federal courts, polygraph results are typically not admissible unless specifically permitted by the judge under particular circumstances.
Q5. How long does a polygraph test usually take? A typical polygraph examination lasts between 1 to 3 hours. This includes a pre-test interview, the actual testing phase where questions are asked and physiological responses are recorded, and often a post-test discussion of the results.
References
[1] – https://liedetectortest.uk/polygraph-questioning-techniques
[2] – https://sgp.fas.org/othergov/polygraph/ota/conc.html
[3] – https://liedetectortest.com/polygraph-examiner/the-role-of-baseline-responses-in-polygraph-testing-why-they-matter
[4] – https://pmc.ncbi.nlm.nih.gov/articles/PMC6654171/
[5] – https://sgp.fas.org/othergov/polygraph/ota/varieties.html
[6] – https://antipolygraph.org/documents/handler-countermeasures-2009.pdf
[7] – https://polygraph.org/docs/goodson_re_breathing_instructions_wg_changes.pdf
[8] – https://www.nationalacademies.org/news/polygraph-testing-too-flawed-for-security-screening
[9] – https://www.lawinfo.com/resources/criminal-defense/are-lie-detector-tests-admissible-in-court.html
[10] – https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2019.00114/full
[11] – https://pubmed.ncbi.nlm.nih.gov/16005091/
[12] – https://www.executiveprotectiongrp.com/blog/lie-detectors-admissibility-in-court
[13] – https://polygraph.org/docs/decision_accuracy_of_the_ri_screening_test.pdf
[14] – https://antipolygraph.org/documents/dodpi-relevant-irrelevant.shtml
[15] – https://morganpolygraph.com/index.php/2024/06/14/understanding-physiological-responses-in-polygraph-examinations/
[16] – https://golawenforcement.com/police-officer-hiring-process/polygraph/
[17] – https://www.nationalacademies.org/read/10420/chapter/3
[18] – https://www.americanassociationofpolicepolygraphists.org/standards-and-principles
[19] – https://polygraph.org/docs/polygraph_1999_281.pdf
[20] – https://www.stat.cmu.edu/tr/tr766/tr766.pdf
[21] – https://privateinvestigatorokc.com/how-polygraph-examiners-write-post-test-reports-for-clients/
[22] – https://papers.ssrn.com/sol3/papers.cfm?abstract_id=5202561
[23] – https://www.nationalacademies.org/read/10420/chapter/7
[24] – https://www.nationalacademies.org/read/10420/chapter/6
[25] – https://www.nashvillecriminaldefenseattorneys.com/blog/Unveiling-the-Truth-Dispelling-Myths-About-Lie-Detectors_AE17.html
[26] – https://pubmed.ncbi.nlm.nih.gov/30284848/
[27] – https://liedetectors-uk.com/blog/rapport-in-polygraph-examinations/
[28] – https://sgp.fas.org/othergov/polygraph/ota/validity.html
[29] – https://www.bbc.com/future/article/20160412-can-you-beat-a-lie-detector-test
[30] – https://www.vox.com/2014/8/14/5999119/polygraphs-lie-detectors-do-they-work
[31] – https://www.dni.gov/files/documents/ICPG/ICPG-704-6.pdf
[32] – https://houlahan.house.gov/news/documentsingle.aspx?DocumentID=4498
[33] – https://www.dol.gov/sites/dolgov/files/WHD/legacy/files/eppac.pdf
[34] – https://www.justice.gov/archives/jm/criminal-resource-manual-262-polygraphs-introduction-trial
