A: It is best used to verify a person's truthfulness and is often called a Lie Detector Test.
A: The theory behind the polygraph is that when a person has to deal with something or someone that poses an immediate threat to his / her well-being, there are certain physical changes that takes place in that person's body. In the case of a polygraph test, if a person is being asked a question and he / she lies to it, he / she feels threatened by that lie and generally this causes a change in the parameters that the polygraph measures.
A: Polygraph testing is a fairly new concept in South Africa, especially in disputes relating to employment relationships. There is no legislation at this point to control the use of the test or to protect the employee's rights against the abuse of the test.
A: 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 the right to have an interpreter, if necessary.
- Should he/she prefer, another person may be present during the examination, provided that the person does not interfere in any way with the proceedings.
A: Generally, the employers are permitted to use the polygraph 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.
- Combating serious alcohol, illegal drugs or narcotics abuse and fraudulent behavior in the company.
- The employer is combating deliberate falsification of documents and lies regarding the true identity of people involved.
A: Every Examinee has some degree of nervousness when doing a polygraph test for the first time. However, nervousness generally stays constant for the duration of the examination and when a person is being asked the questions.
A: In general, existing medical conditions would not have any effect on the results but the Examinee should disclose any serious medical conditions to the Examiner in order to determine the person's suitability to undergo the test.
A: Certain parameters on the polygraph might be affected by it and any use of illegal drugs and alcohol before the test should be disclosed, otherwise it is advised to undergo the test when the Examinee is sober and not under the influence.
A: Although there is no evidence indicating that it is dangerous to an unborn baby, it is advisable to not undergo the examination due to the psychological stress that might be experienced by the pregnant mother.
A: The accuracy rate varies between the different studies that have been done but it's accuracy is estimated above 98%.
A: Polygraph results cannot be released to any person but the authorized person. Generally it is the person who has undergone the polygraph test (examinee), or anyone specifically designated in writing by the examinee, firm, corporation or government agency that requested the examination.
A: 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.
The general view of the CCMA is that polygraph evidence should not be the only evidence that the employer should rely on when dismissing an employee on misconduct and that there should be other evidence supporting the results of the polygraph test. The polygraph is an useful tool to assist in an investigation leading up to dismissal or disciplinary action. Of course every case should be decided on the merits and will greatly depend on the circumstances of each case.
Polygraph tests may not be interpreted as implying guilt but may be regarded as an aggravating factor especially where other evidence of misconduct is present. In other words, polygraph test results alone, are not a basis for a finding of guilt. It can be used only in support of other evidence.