10 Things you need to know before taking a Lie Detector Test

Since its introduction in 1921, lie detector testing, as well as its accuracy, has always been a controversial issue in both the scientific and public domains. In fact, despite the popularity that it has gained in the cultural realm over the years, the veracity of polygraph tests continues to plague our endless search for truth.

Xenophanes once said: “Pure truth no man has seen, nor shall ever know.”  While there may be some truth in this statement, man’s search for truth did not waver. Since the beginning of civilizations, man has struggled to distinguish the lies from the truth of his very existence and since then, techniques have been invented and reinvented to seek out the truth and weed out the lies.

One of the most prolific truth-seeking techniques that man has developed is the association of truth and lies to the physiological reactions exhibited by a person in the face of deception. Primitive as it is for some people, this simplistic technique has been used through the years, and up to this date, it has remained the most important consideration in truth-seeking examinations. This led to the modern-day polygraph or lie detector test.

As in every truth-seeking process, the polygraphic lie detection process starts with research. Relevant information on the examinee and the facts about the case surrounding the examination are gathered and studied. Action plans are also created before the actual testing is conducted. Once completed, the actual lie detection examination can start.

Lie Detector Testing is subdivided into three different stages:

The Pre-Exam Interview, The Polygraph Exam, and The Post-Exam Interview. This is typically administered by a professionally trained and certified polygraph examiner or polygraphist using a computerized, state-of-the-art polygraph technology in a comfortable and climate-controlled office.

Pre-Exam Interview

The first stage of the polygraphic lie detection test is the Pre-Exam Interview. During this stage, the purpose of the examination is made clear to the examinee. This stage is where the examinee is advised of their rights, including the constitutional rights to obtain a legal counsel or express unwillingness to undergo the examination. It is also during this stage that the examinee is asked for their version of the story and made aware of the questions as well as the procedure and instruments that will be used in the actual polygraph examination. Once all of these are done, the polygraph components—usually consisting of sensors for collecting, measuring, and recording physiological data—are attached to the examinee.

Polygraph exam

The second phase of the lie detector test is the test phase, otherwise referred to as the Polygraph exam. During this part, the examiner establishes the baseline readings or, for the examiners, the tonic. The examinee is then asked about known questions, including but not limited to personal questions like the name or the age, all in the form of questions answerable by Yes or No. The examinee is also asked about character questions, to which most examinees feel uncomfortable answering due to its nature which may be personally or socially unacceptable. Though the questions are diverse in nature, there are standard limitations to the type of questions that are asked during the test, which should not be personal or intrusive. These types of questions include beliefs—religious, political, or racial, and sexual orientation and activities. The Polygraph Exam stage is when the actual test occurs. With the questions reviewed and formulated during the Pre-Exam Interview, the examinee is asked to answer with a Yes or a No. These questions are asked for a minimum of three times with a pause in between each one for the duration of this particular stage of the lie detection test.

Post-Exam Interview

Immediately after completion of the Polygraph Exam, the third and the last portion of the Lie Detector Test, the Post-Exam Interview, follows. During this phase, the examiner does the job of analyzing, interpreting, and evaluating the physiological data gathered during the testing procedure. It is during this stage that the examinee is asked to explain about their reactions noted from the charts during the Polygraph Exam phase.

Since the polygraphic lie detection test is designed in such a way that the physiological changes in a person are measured and recorded both for observation and comparison, the controversy about its veracity has remained. The underlying theoretical idea that changes in the pattern of psychophysiological reaction is exclusive to deception is questionable for most critics. Dr. Saxe and Israeli psychologist Gershon Ben-Shahar even went as far as saying that validity studies, such as the polygraphic lie detection test, are impossible to conduct properly.

It is true that lie detector tests are not infallible. However, as Nietzsche once said, “There are no facts, only interpretations.” With the benefit of over 250 studies regarding the accuracy of lie detector testing over the last 25 years, it has survived claims of inaccuracy from polygraph test critics and has remained one of the most effective ways of truth and lie verification.

10 Things you need to know

  1. The Examiner should be qualified in Psychology in addition to being accredited with the APA
  2. No one should say it is 100% accurate… 98% at best due to variances like in any professionally conducted test
  3. It should not be cheaper for 1 question or a short and long version of the test. Process is Process!
  4. The examiner should not be saying how they are better than the rest as that means they are an independent 1 man band!
  5. The test should be carried out in a systematic way and the examiner should be conducting extensive fact finding as part of the psycho-analysis
  6. The cheapest test is not necessarily the best – Come on! When in life is cheap also the best quality?
  7. Every examiner brings different personal experience to the table so make sure they are specialised or from a company that has specialists for different types of tests
  8. Don’t just book If someone can come out in the next couple of hours! If someone has not got bookings it says something!
  9. The examiner should not be charging extra for reports – Cheap Test + Expensive Report is not a Cheap Test!
  10. Go to a reputable company rather than an independent as they will have better standards and procedures.


Choosing a Reputable Lie Detection Company

If you’re in need of lie detection services, chances are you’re in a life-changing situation today. You could be looking at potential employees for your company. You might have suffered theft, bribery, and fraud within your organization. Your spouse might have allegations of infidelity. During these trying times, a trusted lie detection company can save you by finding the fraudsters ruining your life.

The lie detection industry is vast, and many detective companies have sprouted throughout the UK today. Which one among them is trustworthy enough to meet your circumstances and needs? Here is how you should choose a reputable lie detection company.

Company History and Length of Practise

Finding out if someone is lying takes time, practise, and lots of effort. Thus, lie detection services are better if they are conducted by a company that’s already been a game player for several years.

Company reputation is a main factor to consider in hiring a lie detection firm. Look for the lie detection company’s length of service first before jumping in to their offers. A reputable company should have years of experience in polygraph testing and other lie detection practices. It should include a roster of professionally trained investigators that can conduct tests properly and provide impartial results.

It doesn’t mean that new firms aren’t that helpful, though. You may also book a younger lie detection company if it has certified and reputable examiners and if they have successfully helped satisfied clients from the time the company is established.

Number of Clients Helped

Reputable lie detection companies have ideally served a lot of clients locally throughout their years of service. These companies have handled several cases filed by people within its area. But the competition isn’t just about the numbers, it’s also about the success rates of these cases and the satisfaction rate of previous customers who hired their services.

The more satisfied customers they have, the better your assurance that they can really provide excellent services for your lie detection needs.
Examiner Credentials

There are only a few accredited polygraph examiners in the country. These examiners have trained extensively in polygraph studies and have passed stringent credential examinations given by either of the following credential associations:

American Polygraph Association
British & European Polygraph Association
British Polygraph Association

Check the profiles of your chosen company’s lie detection examiners and ensure that they’re accredited professionals. Trained examiners always put integrity, customer privacy, and professionalism in high regard. You’ll get peace of mind knowing that your examiner is well-trained, has integrity, and has dedication to find out only the truth at all times.
Male and Female Examiners

There will be times when a case must call for examiners of a certain gender to ensure better results. Impartial lie detection test firms should have both male and female test examiners ready to cater to the specific needs of every customer.
Quality Tests Controlled by Professionals

Your chosen company should know polygraph testing like the back of their hands. They must be able to offer high-quality, up-to-date polygraph tests using the latest innovations in polygraph science. These tests must be carefully conducted and controlled by professionally-trained and certified examiners in order to yield fruitful results. The test must also be confidential to protect your case and your privacy.

Competitive yet Affordable Prices

Polygraph testing conducted by trained professionals is costly. But it will give your money’s worth if you choose a good firm to conduct the test. Most firms offer varying rates, but the most common rates for lie detection services are fixed and generally play at around £450 and above.
Examiner Should Talk to You, and Not an Agent

Phone the company you wish to hire. Ideally, an examiner should be the one to talk to you. Some lie detector companies actually have agencies that redirect you to agents instead of real examiners. Don’t be fooled by such firms. You should be given to an examiner straight away, so that you may talk about your concerns right even from your first call.

Convenient Offices

After phoning the company, pay a visit to their physical office. The office must be conveniently located to accommodate your home or workplace location and schedules. It’s better if you get a company offering services on weekends to help you despite your busy work week.

In a Nutshell

Choosing a good lie detection company requires a lot of research. You must have your polygraph testing done by a company who has delivered satisfying results to other clients, employs quality examiners, accredited by official organisations, and treats your case with utmost concern for the truth.

Undergoing a lie detector test

The thought of undergoing a lie detector test can be terrifying and intimidate most people. Sitting there with wires and tubes attached and wrapped around your body give most people goose bumps. Even with nothing to hide, the sight of the metal box instruments sitting next to you will strike momentary fear into you. How then the lie detector does works and what are the procedures involved in taking polygraph tests?

Procedures involved in a polygraph test.

Mandate: In order for lie detector to be used, the first step is to get the mandate for the polygraph expert approved by the government, law enforcement and security organizations, the legal community, the private sector and private citizens so as to be able to administer the test. It is taken to verify the truthfulness of statements regarding a certain issue.

Information gathering: The polygraph examiner will now hold a meeting with the clients during which he will gather the needed information and facts about the case under investigation. The information and facts provided will form the basis for the polygraph examination. The facts to be used must have been established through thorough investigation.

Pre-test phase:

The examiner will:

  • Inform the examinee about the issue to be investigated.

  • Remind the examiner of constitutional rights, the rights to an attorney and of polygraph test being voluntary.

  • Complete all necessary documentation for the test.

  • Give the examinee a detailed explanation of the instruments to be used and how it works.

  • Answer questions from the examinee and get his version of facts about the issue under investigation.

  • Formulate the questions to be asked during the test.

The next stage is the in-test phase. Before that though, the examiner will have to fasten the components around the examinees the body. The instruments will connect the examinee to the lie detector. The components are specially equipped with sensors that will collect, measure and record information onto the polygraph chart.

The components to be used include:

  • Blood pressure cuff: it is used to obtain a continuous tracing of the examinee’s cardiovascular activities and it is attached to the examinee’s upper arm.

  • Pneumographs: They are used in monitoring respiratory activities like breathing pattern and it is fastened around the chest and the abdominal area.

  • Two protruding electrodes called galvanometers: They are fastened to the examinee’s fingers and it is used in monitoring sweat gland activity.

The examiner will then have to conduct a functionality test of the lie detector. This is to ensure that the lie detector machine is in perfect shape before the examination commences.

In-test or Chart-collection Phase: This is the stage where the polygraph test takes place. The examiner will put together a minimum of three and maximum of six separate tests with each of them lasting for about 5 minutes.

The examinee’s psychological data will be collected continuously during the test. The collected data will be measured and recorded on the polygraph charts. There will be a two-minute relaxation period between each test.

Once the test has been completed, the examiner will analyze and interpret the collected psychological data. He will also evaluate the collected data and from his professional opinion on the issue. The opinions could be:

  • NDI – No Deception Indicated: The subject is telling the truth

  • DI – Deception Indicated: The subject is not telling the truth.

  • INC – Inconclusive: The evaluation of the physiological data is inconclusive.

  1. Post-test Phase: This is the last phase, the examiner will in this last stage give the result of the test to the examinee. The examinee will be given the chance to explain the various questions he/she reacted to during the test.

The examiner will give the client a verbal report of the lie detector test and the result. This will be followed by a written report that contains the facts and information that were developed during the examination. The examiner’s professional opinion of the result will be based on the analysis, interpretation, and evaluation of the polygraph data.

Systems and Methodology

The polygraph examinations will be administered using top lie detectors instrument companies such as Limestone Technologies Inc. or Lafayette Instrument Company. The lie detector machine to be used should have state-of-the-art systems of computerized polygraph technology. This will ensure that the examination stage will go smoothly and the results will be interpreted and evaluated accurately. Two of the best lie detectors available are Limestone Polygraph Professional Suite and the Lafayette LX4000

The polygraph charts that are collected are evaluated using a numerical evaluation scoring system that has been designed and agreed upon by  the American Polygraph Association.

If the polygraph charts are computerized, they will be further evaluated using a computer software called the PolyScore. This software is a sophisticated and highly reliable scoring system that uses a mathematical algorithm to read the chart.


For most people, the technique behind the use of a lie detector is foreign. This is the reason why most people get scared when they are confronted by the possibility of taking a polygraph examination.

The lie detector machine has 6 different steps or procedures. Of all those, three steps are the most important: Pre-test phase, in-test or Chart-collection Phase and the post-test phase. As an examinee, it is very important for you to be made aware of certain things such as the fact that lie detector test is voluntary. If you don’t feel like doing it, you can simply contact your attorney to cancel the test.

The pre-test stage involves the preparation of the components and the examination questions. The in-test stage is the main questioning and data collection stage. The post-test stage is the final stage where the examiner analyzes, evaluates, interprets the collected polygraph chart and submits the final result.

Knowing this stages will help you overcome any lie detector test that might be required of you later in the future. The process is actually simple and easy.


What is a Lie Detector

William James once said, “The greatest enemy of any one of our truths may be the rest of our truths.” It is true, since the early civilizations, that man has struggled to find ways to learn more about the truth in and around himself. In the ancient Hindu and Chinese civilizations, physiological reactions have been used to detect lies. Chewing and spitting a grain of rice is their lie detection process, and for the Chinese, a dry grain is indicative of guilt as rice sticking in the mouth is for the Hindus. Since then, despite the technological advancements of the succeeding decades and the development in studies and researches, the main goal and the basis for truth detection has remained unchanged—to detect truth and distinguish it from the lies using physiological indicators. Up to this date, the sole invention to ever take these physiological reactions in consideration is the polygraph, which remains one of the most effective ways to distinguish the truths from the lies.

What is a polygraph (lie detector)?

lie detector (polygraph)

lie detector (polygraph)

The polygraph is an instrument, more commonly referred to as the lie detector. It is used to measure, analyze, and record physiological reactions while the examinee is asked a series of Yes or No questions. Invented in 1921 by John Larson, a medical student and a police officer from Berkeley, California, this machine was originally developed in accordance to the mandate of the then-police chief of Berkeley, August Vollmer, for the police force to use science to be more law-abiding and avoid the third degree. It was first created to identify reactions based on the systolic blood pressure test pioneered by psychologist William Moulton Marston, who later on became more popularly known as the creator of the comic book superheroine Wonder Woman.

The polygraph is known to us as the lie detector, but technically, it may be more apt to call it the “truth verifier” as the process involved in its use revolves around identifying changes in physiological reactions during deception. In fact, the term polygraph is believed to have come from Greek words which mean “many writings” as an allusion to the need for many pens during the use of its analog ancestors. Present-day studies would say that the name polygraph comes from the fact that the machine records several body stimuli responses all at the same time while the individual is undergoing the test.

Despite its name, the polygraph and the painless components that come with it do not, in fact, detect lies. These contraptions are simply used to measure, record, and analyze body indices such as blood pressure, pulse, breathing patterns, and skin conductivity. These physiological indices are believed to reflect certain signs that identify a liar. To measure the following indices, several components are attached to the polygraph, namely, the pneumograph, the galvanometer, and the blood pressure cuff. Some polygraphs also use activity sensors to record arm and leg movements.

Technological breakthroughs in the past decades have improved the retrieval and analysis of the data gathered during the lie detection test. From the primitive and manual rice chewing and spitting of the Chinese, to the early version of the pioneer criminologist Cesare Lombroso modified hydrosphygmograph which associated heart rate and blood pressure to lying, and eventually to Larson’s modern-day polygraph, the retrieval and measuring techniques used as well as the indicators being measured have varied and improved. However, after Larson’s invention, not much has changed except for the recording, data gathering, and analyzing methods which evolved from manual to analog and subsequently, digital and computerized.

Critics, however, question the very basis of the theoretical foundation of polygraphic lie detection instead of its quantitative measurements. According to them, while it may be generally true that lying may cause an individual to exhibit certain physiological reactions, the inherent infallibility of the polygraph rests on its lack of unqualified extent, which raises the basis for challenging its validity and efficacy. Some critics remain skeptical up to this date and they maintain the idea that the polygraphic technology operates purely on assumptions and is prone to error and misconceptions. Senator Sam Ervin, in his lack of faith in the polygraph, even said, “Polygraph tests are 20th century witchcraft.”

Despite its subjectivity and the spurious beliefs toward the polygraph, the simplistic foundation of this lie detection instrument has survived almost a century. Since its introduction in the late 19th century, polygraph technology has barely been improved upon, but the very foundation of the criteria which it employs to accurately detect lies has survived countless centuries. The primitive and simplistic idea that it is stressful for a person to lie, thereby prompting the body to have physiological reactions, gave the polygraph its inherent subjectivity, which until now is still unacceptable to the scientific, legal, and political communities.

Indeed, man’s search for truth has gone on for so long. To this date, it has remained as primitive and as simple as in the early civilizations as manifested by our own lie detector equipment—the polygraph.

Questioning Techniques Used in Lie Detector Tests

A lie detector test, also known as polygraph testing, is becoming a popular method of proving innocence and finding out the truth in the UK today. Although there is widespread criticism of the techniques used in polygraph testing, the credibility of the test itself is still high, given the modern methods and new uniformity regarding the testing system used in lie detector tests.

The main aim of a lie detector test is to find out if the person being tested speaks the truth or not. The test doesn’t read what’s on the person’s mind; it detects changes in the person’s physiological responses as a result of answering questions given to him during the test.

Since polygraph testing is all about questions, answers, and physiological responses, many people ask what exactly is the mode of questioning done during these tests. This article will cover two of the common questioning techniques examiners utilise during a polygraph test.

The Control Question Test Technique

Traditional polygraph examiners use a technique called Control Question Test (CQT) to determine the questions to be asked in a polygraph test. The Control Question Test is widely used in cases involving criminal investigations, but may also be used for other polygraph test cases.

Questions under the Control Question Test technique are divided into two categories, control questions and relevant questions.

Control questions are broad questions related to the case matter, but are asked to make the person concerned about their past truthfulness and credibility. Examples of control questions may include the following:

  • Have you ever lied to anybody before?
  • Did you ever try to inflict harm on a woman before?
  • Have you ever tried to betray a person who trusts you completely?

Some control questions regarding the examinee’s identity and perception may also be asked. These questions are similar to the following examples:

  • Is your name really Joe?
  • Were you born in 1975?
  • Are you 47 years old?
  • Is today Friday?

Relevant questions are asked with respect to the direct case itself. These questions are often answerable by yes and no, just like the control questions. Here are some examples of relevant questions:

  • On 25th May 2016, did you shoot John Williams?
  • Did you steal £700 from the cash register?
  • Have you contacted a drug dealer last 15th of June 2017?

How Control Question Test Works

A truthful examinee gets more physiologically aroused when asked a control question, since these questions imply a casted doubt about his overall credibility. When a truthful person answers a relevant question, he is less aroused because he knows that his answers are not a lie. A higher response to control questions leads to a reading of “non-deception”.

An examinee who fabricates his answers for both the control question and the relevant question will both register high physiological responses. However, when he lies about his answers on the relevant questions, the polygraph may record an even higher response than when he answers the control questions. This leads to a reading of “deception”.

The Guilty Knowledge Test Technique

Polygraph science is now becoming more interested in the questioning technique known as the Guilty Knowledge Test (GKT). The test’s aim is to check the examinee’s guilt by using knowledge that only a guilty person will know.

In this test, the examinee is asked a series of multiple choice questions regarding the case. Here are examples of questions that may be asked under the GKT technique:

  • Did you steal £30, £300, or £3000?
  • Have you used a gun, a knife, or a blade in slashing your wife’s wrists?

A guilty person will recognize the correct choice in such questions, as he knows what happened to the crime or to the case. He can deny the fact that he stole money, or that he used a weapon. But he will likely recall the amount of money stolen or the weapon he used in inflicting harm on his wife. This is referred to as guilty knowledge.

A guilty examinee might try to hide his knowledge by answering an incorrect option. In these cases, the examinee will typically display a spike in physiological changes, indicative of deception.

Wrapping it Up

The two most common questioning techniques utilised by polygraph examiners include the Control Question Test and the Guilty Knowledge Test. Each technique has its own set of questioning methods that spark changes in physiological responses, leading to diagnosis of either deception or non-deception. These two have both been useful in successfully gleaning out the truth from various examinees in cases such as murder, theft, and fraud.

In what cases should a polygraph test be used?

The polygraph is not only widely used by companies but also by private persons. Knowing when and where to use a polygraph is an absolute must-do for anyone who is seeking the truth. As it is publicly known people lie a lot, let us be honest, we lie all the time. Some are very talented liars and while doing it, they hardly give any signs which could make it possible to identify a fraud. Others have very visible signs which clearly suggest that the things that we are being told are not particularly true. That is why a lie detector can prove to be so useful. A professional polygraph accurately monitors reactions of the subjects body to certain questions asked and gives good foundations for the examiner to determine whether the person questioned is lying or not. Below are listed a couple of cases in which a polygraph should be used:

Pre-employment screening

It is very often that companies use polygraphs in order to screen their future employees, especially if their work is to consist of working with classified or sensitive information. Using a lie detector during a recruitment process can re-assure you that the person you want to hire is worth your trust. It can also warn you in situations when a person may be a risk to your business.

Fraud of theft investigations

When faced with an encounter of serious fraud or theft within a company, it is common for the management to perform an investigation. This often is supported with the use of a polygraph. The so-called “lie detector” helps verify the statements of suspects as also gives vital information about the company’s employees.

Monitoring sex offender

Polygraphs are now widely known to be one of the basic tools used to test sex offenders at the end of their sentence or during their probation. Test a convict with a lie detector has many positive aspects. One of the main tasks of such an exam is to verify whether such a person is ready to return to a normal life, without the risk that he or she will commit a similar crime. Polygraphs are also used to check if a convict is complying with the rules and regulations given during probation.

Bank employee control

Some banks use the polygraph in order to verify the truthfulness and honesty of their workers. It is well known that some employees have access to very big amounts of money. That is why banks take the highest caution in order to make sure that the persons given access to highest security locations are not a threat to the well being of funds deposited in the given bank.

Relationship troubles

Every relationship has a time of crisis. People make different mistakes which lead to all kinds of consequences. Some are extremely serious and cause whole relationships to end while others are of a smaller importance and let the relationship go on. When a time comes when one of the partners suspects the other of keeping vital information hidden a conflict arises quickly. One of the ways to identify and fight the problem is by using a polygraph. The lie detector is a professional way of finding out who is the one lying.

False claims

Whenever you are accused of doing or saying something, your basic right is to defend yourself. But in some situations it is extremely difficult to defend yourself if one does not have the appropriate evidence. One of the best ways to achieve such is to undertake a polygraph test. This method has already proved to be very accurate and is used all over the World. Taking part in a lie detector exam is one of the most modern ways of gaining in precise evidence which can easily lead to a full and rightful denial to given suspicions.

Civil cases

In some situations, especially when there is not enough evidence in a certain civil case, the UK law allows the use of a polygraph. The results received may be partly used for proving ones innocence.

Family problems

If you think your child is lying to you or that your family members are not being honest with you or are stealing from you or your business then you have to act fast. One of the common ways of finding out the truth facing this big family issue, is to perform the polygraph test on your family members. At first this may seem to be a bit strange and awkward but at the end of the day, precise results are given which lead you and your family to re-uniting.