Frequently Asked Questions (FAQ)

How accurate is a polygraph test?

According to the American Polygraph Association (APA), more that 250 studies have been conducted on the reliability of polygraph testing over the past 30 years. Independent research results of reputable Universities and Academical Institutions worldwide indicate that depending on the polygraph testing and question format used, the sophistication of the polygraph testing instrumentation and the expertise of the polygraphist, results ranging between 85% and 98% can be achieved. This means that for every 100 people examined with the most reliable question technique and quality instrument by an examiner such as ours, the outcome will be that at least 98 of every 100 examinees will yield a 100% reliable result.

How accurate is voice polygraph?

Voice Polygraph (also known as voice stress analysis / VSA) is a validated PDD system. It has been subjected to many research projects since 1970. It is as reliable as bio-feedback polygraph when used by properly trained and accredited Examiners. The most recent research validating VSA is the Chapman Stathis research paper. Following are links to studies conducted:

When can an employer use truth verification testing?

Generally, employers are permitted to use truth verification testing to investigate specific incidents where—

  • Employees had access to the property which is the subject of the investigation;
  • There is a reasonable suspicion that the employee was involved in the incident;
  • There has been economic loss or injury to the employer’s business like theft of company property;
  • The employer is combating dishonesty in positions of trust;
  • The employer is combating serious alcohol, illegal drugs or narcotics abuse and fraudulent behaviour within the company;
  • The employer is combating deliberate falsification of documents and lies regarding true identity of the people involved.

Can someone be forced to take a polygraph test?

It is against the Constitution of South Africa to compel a person to undergo a polygraph examination, unless she or he consents to it. The consent must be in writing.

  • The individual should be informed that—
  • the examinations are voluntary;
  • only questions discussed prior to the examination will be used;
  • he/she has a right to have an interpreter, if necessary;
  • should he/she prefer, another person may be present during the examination,
  • provided that person does not interfere in any way with the proceedings;

Are polygraph results accepted in court?

Polygraphists have been accepted as expert witnesses whose evidence needs to be tested for reliability. The duty of the commissioner is to determine the admissibility and reliability of the evidence. Polygraph test results may not be interpreted as implying guilt but may be regarded as an aggravating factor especially where there is other evidence of misconduct. In other words, polygraph test results, on their own, are not a basis for a finding of guilt. It can be used only in support of other evidence. 

Are there ways to beat a polygraph test?

Polygraph examiners are trained to detect attempts to employ counter measures during polygraph testing.