polygraph lie detector test pretoria, gauteng, south africa

 

Polygraph Institution Company Logo

Polygraph Institution

African Continent

Contact us         

 

 

 
 

 

 

 

Home Services FAQ Instrumentation CCMA

 

 

 

 

 
 
 

Frequently Asked Questions

 
What is a polygraph / lie detector?
History of the polygraph
How does a polygraph work?
What procedure is followed during a polygraph test?
How accurate is a polygraph test?
Can a person be forced to take a polygraph test?
Can nervous tension affect the polygraph result?
Which topics will not form part of a polygraph test?
Substantiating truthfulness by taking a polygraph test
How can a polygraph assist businesses and managers?
Investigative agencies making use of a polygraph 
How confidential is a polygraph examination?
How do you select a Polygraph Examiner?
 

 

What is a polygraph / lie detector?

 

The polygraph is an instrument that measures some of the physiological changes that take place in the human body when a person tells a lie. This instrument simultaneously measures

 

- thoracic and abdominal breathing patterns
- changes in the blood pressure
- and resisting electrical sweating
 
This instrument is also referred to as a lie detector. Polygraph originates from the Greek language and literally means "multi writer". In other words, the polygraph measures multiple reactions, allowing for proper comparison and evaluation and sets it apart from other less accurate devices that only measures one reaction.
 
 

History of the polygraph

 

-

The art of detecting deception is as old as mankind itself. Different methods have been employed to detect deception. In modern times, more scientific methods have been developed to uncover deception.

-

Cesare Lombroso was the first person to utilise an instrument for the purpose of detecting lies in 1895. He measured the changes in blood pressure and in pulse rate with a Hydrosphygmograph.

-

John Larson (1921) was the first person to use a continuous method of recording changes in blood pressure and pulse rate, and used more than one measurement to detect deception.

-

Leonarde Keeler (1926) developed a more complex recording instrument that measured blood pressure changes, pulse rate and respiration. The Galvanograph was added in 1936.

-

An improved questioning technique was developed by Reid in 1942 through adding control questions to the examination.

-

In 1948 the first polygraph school was opened by Keeler.

-

Backster developed the Zone Comparison question technique in 1961.

-

The first electronic polygraph was introduced by the Stoelting Company in 1974.

-

Many studies on the polygraph have been conducted in the USA and continuous research and development is taking place in these fields. In today's modern society most examiners use computerised polygraph instruments.
 
 

How does a Polygraph work?

 
When a person perceives a threat, the body automatically reacts to the threat. This reaction is referred to as the "fight or flight" reaction. The body readies itself either to fight off the threat or to flee.
 
When someone tells a lie it means that truth is a threat to that person. Consequently, certain physiological reactions takes place in the human body which a person cannot control and which can be measured by a Polygraph.
 
The polygraph instrument collects physiological data from a minimum of three systems of the human body. Pneumograph tubes are placed over the examinee's chest and abdominal area to record the breathing patterns and finger plates are attached to the fingers to record the sweat gland activity. A blood pressure cuff will then also record cardiovascular activity. The reactions are charted by the polygraph instrument and reflected on charts printed from the recordings.
 

 

What procedure is followed during a Polygraph?

 

A typical polygraph examination will include four periods which is referred to as:

 

 

-

Pre-test Phase

-

Chart Collection Phase

-

Post-test Phase

-

Test Analysis Phase

 

 

This procedure usually takes between 60 minutes to 90 minutes and is done one on one.

 

Pre-test Phase: The Polygraph Examiner will complete the required paperwork and explain the theory of the polygraph in an understandable way to the candidate. The candidate will be given the opportunity to discuss their roles or perceptions in the case under investigation and to provide relevant information. During this period, the Examiner will discuss the questions to be asked and familiarise the candidate with the testing procedure.

 

Chart Collection Phase: During this phase the Examiner will conduct the examination and collect a number of polygraph charts. No questions will be asked during the examination that was not previously discussed and reviewed with the candidate.

 

Post-test Phase: The Examiner will do an analysis of the charts and render an opinion true to the person taking the test. Further analysis of the charts collected might be necessary in certain circumstances and the results will then be released with the report and/or a preliminary verbal results is given to the authorised person. The Examiner when appropriate, will offer the candidate an opportunity to explain physiological responses in relation to any questions asked during the examination.

 

 

How accurate is a polygraph test?

 

In 250 different studies conducted in this regard over the past 75 years, the preponderance of available information indicates that the polygraph technique is reliable in as many as 98% of specific issue investigations. This proves the polygraph is more reliable than most, if not more than other conventional methods of investigation.

 

 

Can a person be forced to take a polygraph test?

 

Unless stipulated in a contract, no person can be compelled to undergo a polygraph examination. However, it must be kept in mind that the polygraph is a quick and effective tool to assist in any investigation and could be the quickest and most effective way of excluding an innocent person from the continuous investigation.

 

 

Can nervous tension affect the polygraph result?

 

The polygraph technique allows for a persons general nervous tension. Most people will be nervous before and during a polygraph examination. This however only affects the level from which recordings are made and does not affect the result of the examination. In other words the level of nervousness will affect the individuals physiological baseline, but it will not be affected by the variations on the baseline and consequent result of the examination.

 

 

Which topics will not form part of a polygraph test?

 

An Examiner will never ask any questions on any of the following topics 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 and activities

 

 

Substantiating truthfulness by taking a polygraph test

 

It often happens that an individual is unfortunately or unjustly implicated in a crime or marked as a target 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.

 

 

How can a polygraph assist businesses and managers?

 

A polygraph test can assist in helping to provide information regarding the integrity of employees quickly and accurately. Therefore it can be of great value in the appointment of personnel and also to establish the culpability in cases of employee theft or fraud. It is therefore suggested that the polygraph is an invaluable aid in any personnel integrity maintenance program.

 

 

Investigative agencies making use of a polygraph

 

Most agencies have found that the polygraph can be used most effectively to limit the number of suspects. The results can normally indicate which person/s was involved in the investigated matter, and in some instances admissions of guilt are obtained during or after a polygraph examination. However it must be stressed that the polygraph does not replace an investigation.

 

The polygraph is a valuable aid in investigations, and can add valuable information to any investigation. The polygraph helps to focus the investigation, and for this reason saving time, money and manpower. This procedure helps to establish the bona fides of honest persons implicated in a case quickly and efficiently.

 

 

How confidential is a polygraph examination?

 
Every effort is made to ensure the privacy and security of an accused and the client's information. All files are restricted to those immediately involved in the procedure. The result of an investigation or even the fact that an examination was conducted is carefully guarded information. The information will only be disclosed to those who (and others as may be required by due process of law) is entitled to the facts concerning the results.
 

 

How do you select a Polygraph Examiner?

 

When choosing an examiner, it is very important to ensure that the individual is fully qualified from an accredited polygraph school and is a registered member of a South African Polygraph Federation or Association. Only reputable polygraph companies with a proven track record and proper references should be considered.

 
 

 

 

 

 

 

 Hetjou! Web Design (c) 2015