Generally Asked Questions

When it comes to polygraph examinations and lie detector tests people are often curious, and they should be. Polygraph testing plays an increasingly large role in the world, and South Africa is no exception. Here we try to answer some of the frequently asked questions regarding polygraph examinations and other lie detection technologies. If however you have a question that is not answered in this section, please do not hesitate to send us an email and we will revert back to you with an answer as soon possible.

Contact Us.

Polygraph and Lie Detector Testing in South Africa

What is a lie detector test?

There are numerous 'lie detector' tests currently on the market, some more effective than others. Polygraph examinations are often referred to as a lie detector test as well. A lie detector test is a test designed to determine if a person is telling the truth or not when answering a pre-determined set of questions. The term 'lie detector' is a term of convenience, as 'lie detector' instruments are designed to monitor various aspects of a person's physiology when answering questions as associated proximity data in order to make an inference on the person's honesty, or dishonesty when answering the questions. Over the years a lot of research has been conducted regarding the accuracy and validity of 'lie detector' tests, and the results have differed between the various instruments, types of tests and question techniques. The Polygraph Institute of South Africa only uses the most accurate available question techniques that have been scientifically determined to be valid and reliable.

What are the different types of lie detectors?

Broadly speaking there are four different types of 'lie detectors' currently available internationally. These are polygraph examinations, Converus EyeDetect, fMRI and voice stress testing. The different types of tests are fundamentally different and monitor different aspects of human physiology in attempting to determine when a person is telling the truth, and when a person is telling a lie.

1 - Polygraph Examinations:

Polygraph examinations are currently the leading means of detecting deception in the word. Its success stems from the fact that it was the first detection of deception technology that was researched and implemented as a forensic tool. This meant that polygraph testing had been rigorously researched, developed and improved since the first 'modern day' polygraph was invented in 1921, making it the most developed and advanced means of detecting deception currently in existence. The polygraph instrument monitors various physiological changes that occur in the body of the examinee while they are answering a set of predetermined questions. These changes taken into account during a polygraph examination have been correlated to deception on a statistically significant level. There are different question techniques and test methods designed to focus on various situations such as screening examinations and specific incident examinations. Specific incident examinations are used to assist in investigations and currently has the highest accuracy rating of all 'lie detector' tests. You can find more information on how polygraph examinations work here: How Polygraph Examinations Work.

2 - Converus EyeDetect

EyeDetect is the world’s first lie detection technology that accurately detects deception in 30 minutes by analyzing eye behavior. It’s also cost-effective, efficient and secure. First conceived in 2002, it’s the first ocular-motor deception detection solution. The same scientists credited with computerizing the polygraph in 1991 developed EyeDetect. In September 2013 the technology was given the brand name EyeDetect. It’s a new way for organizations to manage risk and ensure workplace integrity, and for law enforcement agencies and governments to detect deception. Ultimately, it helps protect countries, corporations and communities from corruption, fraud and threats. EyeDetect boasts 86 percent accuracy when pre-screening candidates or periodically screening employees. In the mock crime study at the Tecnológico de Monterrey in Mexico, as well as in a study published in the Journal of Experimental Psychology: Applied (Sep. 2012), EyeDetect achieved 85 percent accuracy. But in more recent field studies, the science team has found a slighter higher rates of accuracy. It is also the only other detection of deception tool currently in use by the Polygraph Institute of South Africa.

3 - fMRI

Functional magnetic resonance imaging, or fMRI, is a technique for measuring brain activity. It works by detecting the changes in blood oxygenation and flow that occur in response to neural activity – when a brain area is more active it consumes more oxygen and to meet this increased demand blood flow increases to the active area. fMRI can be used to produce activation maps showing which parts of the brain are involved in a particular mental process. Research shows that an electroencephalogram and the fMRI may achieve results of 87% accuracy. However both test are intrusive (the examinee is connected extensively to medical instruments or is inserted into a large tube). Both methods are very costly, require expensive equipment and extensive examiner training. For these reasons, neither is a viable lie detection solution for large groups of people, such as in pre-employment screening.

4 - Voice Stress

There are various different voice stress testing instruments currently marketed. VSA software programs are designed to measure changes in voice patterns caused by the stress, or the physical effort, of trying to hide deceptive responses. VSA programs interpret changes in vocal patterns and indicate on a graph whether the subject is being "deceptive" or "truthful." Unfortunately, most independent studies show that voice stress testing has a low accuracy rating when used to detect deception. According to a recent study funded by the National Institute of Justice (NIJ), two of the most popular VSA programs in use by police departments across the country are no better than flipping a coin when it comes to detecting deception. More information regarding the study is available here: National Department of Justice (NIJ) The Polygraph Institute of South Africa does not make use of nor endorse the use of voice stress testing.

What can polygraph examinations be used for?

Polygraph examinations are used by businesses, companies in various sectors, security operators, financial institutions, private investigators and of course government agencies such as specialized crime units, military organizations and police services across the globe. Due to the versatile nature of polygraph examinations it can be adapted to address a variety of different issues in a variety of different ways in order to approach the situation in question in the best suited manner. That means that polygraph examinations can be implemented to suit the need and budget of your business or institution to maximize its effectiveness.

In South Africa, polygraph examinations are most commonly used to assist in criminal investigations for private and public sector, for pre-employment screening, for continuous integrity screening programs to monitor criminal and unethical activities at a company or institution, and for statement verification. If you would like more information on the different ways that polygraph examinations can be implemented, please click here: Different Types of Polygraph Testing.

Are polygraph examinations legal in South Africa?

Yes, if implemented correctly polygraph examinations adhere to The Constitution of South Africa as well as the regulations and standards of practice of the Southern African Polygraph Federation which is a divisional member of the American Polygraph Association. This is why it is important that the examinations are conducted by professionals who are qualified and accredited, and in a manner that is fair and ethical. If properly conducted, polygraph examinations can also play a significant role in strengthening the evidence submitted during labour disputes, arbitration processes and other legal proceedings. Do note that there are certain regulations and requirements that need to be adhered to in order for the examination to be considered valid, which will be discussed in an upcoming section.

What are the minimum requirements for a valid polygraph examination?

There are certain prerequisites that should be kept in mind when determining whether a polygraph examination is valid. This is of particular importance when considering the use of polygraph results as evidence. The following are minimum requirements for the acceptability of a polygraph in a disciplinary hearing, the CCMA or in court:

The Polygraph Examiner

1 - The polygraph examiner must have been trained by an accredited institution to ensure that they are knowledgeable on the subject and that they implement the examinations correctly and fairly.

2 - The polygraph examiner must be a member in good standing with a professional body such as the Southern African Polygraph Federation. This implies adherence to a strict code of conduct and ethics. Professional organizations also provide updated advanced training seminars which members are obligated to attend.

3 - The polygraph examiner must have attended an internship from a qualified and experienced examiner to gain field training and experience.

4 - The polygraph examiner must be qualified and experienced in analyzing the data collected during a polygraph examination in order to ensure accurate results. The data collected during polygraph examinations must be assessed manually and computerized evaluation may be used only for the purpose of quality control or to obtain other opinions.

5 - The polygraph examiner must be independent, impartial and objective during the entire process.

6 - The polygraph examiner must treat the examinee with respect and dignity, and should answer all questions posed by the examinee regarding the examination process and equipment. The polygraph process and technique must be explained to the examinee, and it is the responsibility of the examiner to ensure that the examinee give informed consent before proceeding with the examination.

7 - The polygraph examiner must be able and willing to testify as an expert witness.

The Examinee

1 - The examination must be conducted voluntarily and can only be conducted once the examinee has given their informed consent. The informed consent must be given in writing prior to the examination.

2 - The examinee must cooperate with and adhere to all lawful instructions given by the polygraph examiner during the examination process.

3 - The polygraph examiner needs to determined whether the examinee is medically fit to undergo the polygraph examination. The examinee should, as far as can be ascertained, free of serious illness or medical ailments.

4 - The examinee should preferably not be under influence of alcohol or drugs during the polygraph examination.Polygraph Instrumentation

5 - The examinee should preferably, not have been subjected to accusatory interrogation prior to the examination.

The Polygraph Instrument

1 - The polygraph instrument must be in good working order during the polygraph examination.

2 - The polygraph instrument must record at least the following data streams:

2.1 - Changes in heart rate and blood pressure through a medical blood pressure cuff.

2.2 - Upper body muscle movements and respiration using two pnuemograph channels.

2.3 - Electral dermal activity using EDA nodes.

3 - The environment in which the examination is administered should be conducive to proper polygraph testing, i.e. a quiet environment without serious visual or audio interference.

The Polygraph Technique

1 - An internationally accepted question technique that has been scientifically proven to be valid and reliable must be used.

2 - All questions must be thoroughly reviewed with the examinee before the collection of charts takes place and the examinee needs to indicate that they understand all the questions put to them.

3 - A minimum of three polygraph charts should be recorded during the chart collection phase of the examination unless specifically indicated otherwise by the technique developers.

Can a person be compelled to undergo a polygraph examination?

Unless contracted as such, no person can be compelled to undergo a polygraph examination. This is in keeping with section 35 of the South African Constitution and also the Criminal Procedure Act. That being said, the investigating team can make negative inferences based on the fact that a person is not willing to undergo a polygraph examination. This negative inference can also be submitted as part of a bundle of evidence in support of a dispute, especially if supported by other corroborating or supportive evidence and even more so if the other persons identified as possible perpetrators did not refuse to undergo the examination.

Do polygraph instruments need to be calibrated?

The calibration of polygraph instruments was a historical requirement for the analogue polygraph instruments which used a lot of mechanical parts. Modern day polygraph instruments are electronic components that work in conjunction with software specifically designed to collect and process the data collected by the electronic components. As supported by this letter from the Lafayette Instruments company, it is not a requirement for the electronic polygraph instruments to be calibrated: Polygraph Instrument Calibration Letter.

It is a requirement that the instrument should be in a proper working condition, and in the event that a fault is detected or that the instrument had to undergo repairs, it is recommended that the instrument be scrutinized with a functionality test to.

Does being nervous affect the polygraph examination result?

The polygraph technique allows for the level of a person’s general nervous tension. Most individuals will be nervous before and during a polygraph examination. Nervousness in itself is not taken into account during the assessment of a polygraph examination, and being nervous does not affect whether a person is being perceived as truthful or deceptive during.

What will not be asked during a polygraph examination?

No examiner of the Polygraph Institute of South Africa will inquire into the following areas:

• Religious beliefs or affiliations.

• Beliefs or opinions regarding racial matters (except to the extent that any such biases could interfere with one’s ability to fairly and objectively perform his or her job).

• Political beliefs or affiliations.

• Beliefs, affiliations or lawful activities regarding unions or labor organizations.

• Lawful sexual preferences or activities.

Can I cheat the polygraph test?

Many people have tried to find ways to beat the polygraph test, and without success. In season 5, episode 24 of Mythbusters the crew attempted to use some of the ways people claim that they can beat the polygraph with, and failed dismally: Mythbusters - Confederate Steam Gun / Beating the Polygraph.

The fact is that all of the methods that people claim can beat a polygraph test are well known to polygraph examiners themselves who use specialized equipment and training to monitor for what they term 'countermeasures.' Research also indicated that even innocent people who attempt to use countermeasures to manipulate the data of a polygraph examination are more likely to fail the test. So the lesson is very clear, the most effective way for a person to pass a polygraph examination, is simply to be honest with the polygraph examiner.


How accurate is a polygraph examination?

Literally hundred of studies have been conducted over the decades to determine the accuracy of polygraph examination results, and the answer is dependent on the type of test being implemented. There are different types of question techniques and the different techniques have varying degrees of accuracy. In general, the majority of research indicates that polygraph examination accuracy has been rated between 88% to 95% ranging from screening examinations to specific incident examinations. If implemented correctly and in accordance to the regulations and procedures as stipulated, it is to date the most accurate means of detecting deception in the world.

Are polygraph examinations considered confidential?

Every effort is made to ensure the privacy and security of an examinee or client’s information. All files are restricted to those immediately involved in the procedure. The result of an examination is carefully guarded information. Only the individuals sponsoring the examination (and others as may be required by due process of law) are entitled to the facts concerning the results.

Do investigative agencies make use of polygraph examinations?

Multiple investigative agencies globally make use of polygraph examinations. These agencies have found that the polygraph can be used most effectively to limit the number of suspects. The results normally indicate which person or persons were involved in the matter under investigation, and in some instances admissions of guilt are obtained during or after a polygraph examination.

The polygraph is a valuable aid in an investigation, and can add valuable information to the investigation. The polygraph helps to focus the investigation, thus saving time, manpower and money. It also helps to establish the bona fides of honest persons implicated in a case quickly and efficiently.

Multiple business also make use of polygraph examinations. The polygraph helps to provide information regarding the integrity of workers quickly and accurately. It can therefore be of great value in the appointment of personnel, as well as in establishing culpability in cases of employee theft or fraud. The polygraph is an invaluable aid in any personnel integrity maintenance program.

Are there professional organizations dedicated to the advancement of professional and ethical polygraph use?

There are various organizations dedicated to the professional advancement of polygraph examinations and their use in a fair and ethical manner. The American Polygraph Association is the world's largest professional polygraph institution dedicated to evidence based scientific practices. In South Africa the Southern African Polygraph Federation is an ethics organization that strives to advance the polygraph industry by promoting ethical and fair standards of practice and providing advanced training courses to its members. The Southern African Polygraph Federation is a divisional member of the American Polygraph Association and has signed a memorandum of understanding with the South African Chapter of the Association of Certified Fraud Examiners (ACFE).

How Can We Help You?

We are eager to assist you and your company and to provide you with polygraph examinations of the highest quality. If you have any questions or queries, would like us to give a presentation or if you would like more information on any of the professional services that we provide, please do not hesitate to ask. Our staff members can't wait to hear from you.

Would you like to contact us for a presentation or booking?

Would you like more information regarding polygraph examinations?

Would you like more information on the other products that we have available?


PISA Integrity Assessment Centre A4 Advert: Download

PISA Integrity Assessment Centre Small Advertisement: Download

PISA Integrity Assessment Centre Tri-Fold Brochure: Download