The polygraph is an instrument that measures some of the physiological changes that take place in the human body when undergoing questioning in an effort to obtain truth or deception. It is sometimes referred to as a forensic psychophysiological detection of deception (PDD) or psycho physiological veracity (PV) examination however is mostly known as the "lie detector". The term "polygraph" originates from the Greek language and literally means "multi writer". The name refers to the manner in which selected physiological activities are simultaneously recorded. This sets it apart from other, less accurate devices that only measures one reaction, as opposed to the polygraph's measuring of multiple reactions, allowing for proper comparison and evaluation.

As a Practical matter, however the forensic Psycohopysiologist (FP) measures and records breathing patterns, heart beat, pulse rate and strength, changes in blood pressure, and electrodermal responses in order to obtain physiological evidence of the hypothalamic activity including the sympathetic and parasympathetic subdivisions of the autonomic nervous system during polygraph examination in response to particular questions ask on the test.

When a Question is perceived as threatening, impulses are sent from the frontal lobe through the hypothalamus to the sympathetic system, triggering a sympathetic response.

When the sympathetic system is activated, it immediately prepares the body for “fight and flight” to secrete hormones knows as epinephrine and nor epinephrine, the blood will distributed to the areas in the body where it’s most needed to meet the emergency. This will get the body in a state of alertness. The brain can not distinguish between physical threat and psychological treat therefore the same psychological response will occur at the point of deception.

Psychological Set

It is where the examinee will focus his/her attention to the particular issue or situation which percent the greatest threat to his security or self being while filtering out the lesser threats.

Fear for Deception

Fear of deception will course physiological changes to occur in the subject’s body at the point of deception. Therefore during the polygraph examination the guilty person will focus his attention to the questions that pertains the directly to the issue under investigation (relevant questions) and the innocent person his attention to the (control questions (probable lie).

A polygraph instrument collects physiological data from at least three systems of the human body. Pneumograph convoluted rubber tubes are placed over the examinee’s chest and abdominal area to record breathing patterns and finger metal plates (galvano graph) are attached to the fingers to record respiratory activity. A blood pressure cuff (cardio cuff) will record cardiovascular activity. The reactions are charted by the polygraph instrument and reflected on charts printed from the recordings.

A typical polygraph examination will include periods referred to as a pre-test phase, a chart collection phase, post-test phase and a test analysis phase. This procedure usually takes one to one and a half hours.

During the pre-test the examinee will be informed of his/her legal rights, be asked to sign a polygraph consent form where he among other things, confirm that he/she is doing the test voluntary, complete a personal particular form, the examinee will evaluate the examinees physiological and psychosocial suitability to undergo a test, control questions will be established, instrument will be explained, analysis of case facts will be done and lastly all test questions will be reviewed?

During the chart collection phase, the examiner will administer the examination and collect a number of polygraph charts. A Minimum of two and with certain techniques at least three will be collected. No questions will be asked during the examination that have not been discussed and reviewed with the examinee.

In the post-test phase, the examiner will analyse the charts and render an opinion as to the truthfulness of the person taking the test. The examiner, when appropriate, will offer the examinee an opportunity to explain physiological responses in relation to any questions asked during the examination.

During the past 75 years, over 250 different studies have been conducted in this regard. The preponderance of available information indicates the polygraph technique to be reliable in as much as 85% to 98% of specific issue investigations. This proves the polygraph to be more reliable than most, if not all other conventional methods of investigation.

CLICK HERE - To view the Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques Report

Unless contracted as such, no person can be compelled to undergo a polygraph examination.

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. However, this only affects the level from which recordings are made and does not affect the result of the examination, i.e. although the level of nervousness will affect the individual’s physiological baseline, it will not affect the variations on the baseline and consequently the result of the examination.

No examiner of the Polystaff will ask questions about any of the following areas during an examination:

• religious beliefs or affiliations
• beliefs or opinions regarding racial matters
• political beliefs or affiliations
• beliefs, affiliations or lawful activities regarding unions or labour organisations
• sexual preferences or activities (unless it is the focus of the examination)

It often happens that individuals are unfortunately or unjustly implicated in a crime or marked as targets for accusations or inferences. In many cases, there is no way in which those concerned can restore the trust or protect their reputation from the harm of careless accusations. The polygraph examination provides an excellent opportunity to restore the trust between employee and employer and creates an unequalled opportunity for such individuals to substantiate their truthfulness and prove their innocence.

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 results of an examination or even the fact that an examination was conducted, is carefully guarded information. Only the individual sponsoring the examination (and others as may be required by due process of law) are entitled to the facts concerning the results.

When a client chooses an examiner, it is very important to ensure that the individual is fully qualified from an accredited polygraph school. Only reputable polygraph companies with a proven track record should be considered.

In South Africa there is no legislation regulating the use of the polygraph. Therefore, there is currently nothing prohibiting or preventing the submission of polygraph results to corroborate other evidence in our courts of law. It is also legal to request employees to voluntarily subject themselves to polygraph examinations.

It is very important to note that polygraph results were never intended to provide irrefutable probative evidence to a court of law. The polygraph is an investigative tool and polygraph results should be used primarily to assist investigators in narrowing investigations by identifying suspects and collecting information relevant to the investigation. Polygraph results should therefore be submitted to a court only when they can corroborate other admissible evidence and assist the court in reaching a verdict.

Proper polygraph procedures comply with the contents of the Constitution and the Labour Relations Act in every respect, and actively promote fair labour practices and respect for the human rights of the examinee, because it affords the innocent person an opportunity to be heard and to prove their innocence.

Polygraph results can be utilised in labour disputes and disciplinary inquiries. The acceptance of polygraph examination results will depend largely on the credibility and qualification of the examiner and the way in which the examination was conducted.

Polygraph results have been submitted and acknowledged in a number of Commission for Conciliation, Mediation and Arbitration (CCMA) cases, and are frequently submitted during internal investigations and disciplinary hearings to corroborate other evidence (For more detailed information on specific CCMA cases see on THE LABOUR LAW GUIDE web site).

Being an overt technique, the polygraph is not regarded an unfair labour practice when used as an investigative tool. In terms of the "Report of the Law Commission on Group and Human Rights" (August 1991: socio-economic rights/second generation rights) there seems to be ample room for the use of the technique. It should, however, be handled according to the principles as laid out in the Labour Relations Act.

Investigations require teamwork in order to solve cases. The polygraph examiner is a valuable member of this team and usually works closely with the investigating officer. In order to make decisions regarding the focus of the examination and the questions to be asked during the examination, the polygraph examiner needs specific information about the case under investigation.

The following information is needed:

1. Description of incident
2. Detail of loss and value of loss
3. When did it happen (Date and time)
4. Where did it happen?
5. Who reported the incident and to whom?
6. Who was involved/had access?
7. Who are the main suspects and why?
8. What is the main issue to be addressed during the polygraph examination?

Any additional information that could help the polygraph examiner to understand all the issues and circumstances surrounding the incident should be provided. Note that the sequence of events should also be clear from the information given.

The polygraph is a valuable aid in investigations and helps to focus an investigation by pointing out the deceptive examinees, thus saving time, manpower and money. It also helps to exonerate the innocent person who is surrounded by circumstantial evidence. It is particularly valuable in those investigations that rely only on testimonial evidence. At the same time, polygraph examinations are very helpful in investigations involving multiple suspects by narrowing the focus of the investigation. Specific polygraph examinations are used in cases of misconduct and are aimed at identifying the deceptive, clearing the innocent and clarifying facts under dispute. Results of such examinations are often invaluable aids in directing investigations and providing additional leads for investigation.

• Only apply pre-employment testing insofar as job requirements of the specific post to be filled justify a strict approach to the issue of honesty and reliability.
• Require the applicant to sign a comprehensive consent prior to the examination.
• All questions asked of applicants should be carefully scrutinized to ensure that:
  • The questions are strictly related to the job requirements for the specific position to be filled.
  • No questions are asked which could discriminate in terms of the Constitution or the Labour Relations Act.

Although the different needs of clients will determine the areas of concern, a routine pre-employment examination may address the following:

• Verification of identity.
• Involvement in industrial or commercial espionage.
• Involvement in serious crime.
• Use of illegal substances.
• Verification of information supplied on application form or CV.
• Serious financial problems.
• Alcohol dependence.
• Verification of reasons for leaving previous employment.

In view of the specific examination technique utilized in pre-employment examination, clients are advised not to use more than six relevant questions during an examination.

• It is done with the knowledge and consent of the applicant and is thus not a covert technique. As part of some set selection criteria, it is not discriminatory in nature when applied to positions of trust.
• It can be completed in a short period of time (2 hours), and therefore contribute to the efficiency of the recruitment officer or the Human Resources department.
• It is cost-effective compared to conventional field examinations, as well as the decrease in losses that can be expected from a selected work force.
• The polygraph acts as a deterrent against dishonest applicants and it can lead to better labour relations as it certainly helps to create a climate of honesty. It is beneficial to managers who want to create and maintain a privileged employee corps.
• Ultimately the viability, growth and employment opportunities of a company can be secured through the use of the polygraph, as it yields information that can not be obtained in any other way. This can mainly be attributed to the interviewing skills of an experienced polygraphist. It deals with past behavior (and not with beliefs, attitudes or opinions) as well as information which when gathered for decision making, may be reasonably expected to be inquired into by an employer.

In addition, pre-employment polygraph screening supports the right of employers to base decisions to enter into contract with applicants, on verified information, and supports the employer’s right to protect his business against dishonesty and crime. Last, but most important, it serves as a deterrent to future dishonesty and crime and protects the profitability and viability of a business.

Is defined as those deliberate techniques which a deceptive subject uses in an attempt to appear non deceptive when is physiological responses are being monitored during a polygraph examination.

Any intentional attempt, method or action taken by an examinee to influence the outcome of the Polygraph examination.