What is a Polygragh?
The Polygraph is derived from two Greek words: Poly meaning “many” and graph meaning “writings”.
The name refers to the manner in which selected physiological activities are simultaneously recorded by a conventional or computerised Polygraph instrument.
The Polygraph instrument is a highly sophisticated piece of medical equipment that records continuous physiological data from four systems in the human body, namely: respiration, perspiration, blood volume and heart rate. These responses are produced as a result of a stimulus presented to the subject or examinee in the form of specifically designed and structured questions, whilst the subject is attached to the instrument. The physiological data that are produced by the examinee are recorded on the Polygraph charts, also known as Polygrams, and enable a qualified Polygraph examiner to establish whether or not an individual is being truthful or deceptive regarding his involvement in a specific issue or crime.
Why do people lie?
Since the beginning of time, deception has formed an integral part of human nature. Although it is viewed as morally wrong, it is part of almost every person’s existence. Deception is usually linked to gaining some unjust advantage or avoiding negative consequences. This means that deception is usually deliberate.
In the average person, the conscious decision to tell a lie is usually accompanied by fear. Fear of detection and fear of the consequences.
If a person tells a lie, they know that if detected their lie will be exposed and that person will be left to face the undesirable consequences of their actions. The fear that accompanies this deception will activate a built in alarm system in the person’s body, which we refer to as the Fight or Flight Theory. The autonomous nervous system will detect this immediate threat of being exposed and will respond by creating physiological reactions in the body that are consistent, specific and significant to being measured by the Polygraph instrument.
What does it entail?
A Polygraph examination includes:
1. a pre-test phase
2. a chart collection phase
3. an analysis phase of the data collected during the chart collection phase
During the pre-test phase the examinee is familiarised with the reasons for the examination and gives his or her written consent, allowing for the completion of the test. The examiner must explore the examinees medical background, explain the questions that will be posed during the chart collection phase of the examination, as well as explain how the Polygraph instrument works.
In the chart collection phase the examiner will collect at least two polygraph charts, also known as the polygrams, containing the complete graphical recordings produced by the examinee when confronted with the same set of questions reviewed with him during the previous phase.
During the Analysis phase the examiner will analyse, interpret the charts and render an opinion to the truthfulness of the examinee.
There are a number of variables in this section and the client will be informed of any one of the following test results:
1. Deception Indicated: Person failed the test
2. No Deception Indicated: Person passed the test
3. Inconclusive: Unable to conclude a pass or fail result
4. No Opinion: This usually occurs when a person has been uncooperative during the test phase and the data has been corrupted.
Can nervousness affect the results?
Nervousness is a completely normal feeling that one will experience when having to undergo a polygraph test. Nervousness is a state that exists throughout the test and does not usually cause deceptive responses. It is up to the examiner to explain the process to the examinee and set that person at ease.
How accurate is a Polygraph?
According to The American Polygraph Association more than 250 independent studies confirming the accuracy and reliability of the Polygraph have been conducted by reputable universities and academic institutions worldwide.
While the Polygraph technique is not infallible, research clearly indicates that when administered by a competent examiner, the Polygraph test is one of the most accurate means available to determine truth and deception. Depending on the technique, question format and expertise of the Polygraph examiner studies have indicated that the Polygraph is up to 98% reliable.
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