How accurate is the polygraph?

The polygraph technique is very accurate, however, it is not infallible.
According to the American Polygraph Association, over 250 studies have been conducted over the past
twenty-five years on the accuracy of polygraph testing. It is estimated that the accuracy of the results is in the
range of 90 - 95 %. More recently, research has shown that the accuracy of computerized polygraph testing is up to 98%.


Is the polygraph like the lie detector?

Yes. The polygraph instrument is a scientific, diagnostic instrument which is often called the "lie detector". It would be more appropriate,
however, to call it the "truth verifier".


I am telling the truth but I am nervous about taking a polygraph examination. How does the polygraph establish the difference
between the state of nervousness and reactions as a result of lying?

It is quite normal for an innocent person to feel nervous and the polygrapher is very aware of this. Nervous reactions which are recorded on the charts are not interpreted by the polygrapher as a manifestation of deception. Nervous reactions are completely different from those reactions that are recorded when a person is deliberately lying. The instrument is calibrated uniquely to the examinee's body before running the charts.

Example: You are nervous and walking down a dark street. You heart is racing and you are sweaty and breathing is erratic. Someone jumps out in front of you. You will react in a huge way. Everything happens at once without you controlling it. You sweat more, you heart races faster, your breathing much deeper. Being in a polygraph test can feel like you this person. If you lie your body will react to this even if you try hide it.


Can I know what the questions on the polygraph examination will be beforehand?

Yes. You will be informed of the exact wording of each question that will be asked of you during the course of the polygraph examination. There are no "trick" questions.

How long does a polygraph examination take?

A polygraph examination takes up to 1h30, however, some may take more or less time, depending on the nature of the issue under investigation.

Why does a polygraph examination take so long?

The examiner will give a detailed explanation of the polygraph procedure, how the polygraph works, and he will answer any questions that the examinee may have. The examiner will also take a detailed statement as to the case at hand, then review the questions, run a stimulation / acquaintance test and then run at 3 - 5 charts.

Can you carry out tests in any language?

We can carry out tests in English or Afrikaans. If you need an interpreter for an African language then this has to be arranged by yourself. However we find anyone living in SA cope fine with just English or Afrikaaans.

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