The use of polygraphs is a process fraught with difficulty and the tests may well prove inconclusive, explains industrial relations specialist David Van Rooyen.
A polygraph measures and records bodily activities such as heart rate, blood pressure, breathing rate and skin resistance. It is claimed that any conscious effort by a person to give false information during a polygraph test will cause involuntary and uncontrollable responses in these activities. The test itself involves measuring the person’s responses while answering a series of about eight to
12 questions, which would include three that are specific to the reason for the test. The examiner then interprets the test results. However, while the examiner can form an opinion as to whether or not the person has tried to deceive the polygraph, they cannot say conclusively whether the answers are true or false or if the person is lying.
If tests results are going to be used as evidence against an employee, it is important to know how accurate and reliable they are and whether or not they can be used at arbitration.
Accuracy and reliability
According to the American Medical Association, the American Psychological Association and the National Academy of Science, polygraph tests are unreliable and inappropriate for use in the workplace; they are more art than science with little serious research behind them. In this country, the Health Professionals Council of South Africa has reached a similar conclusion. It is claimed that a polygraph measures the responses generated by emotional stress, but stress may be caused by a number of factors of which lying is only one. It is possible that the questions themselves, such as “did you steal the money?” could make the respondent feel like a suspect and become nervous. The fact that they are being interrogated by a stranger in unfamiliar surroundings could make them nervous. The fear of failing the test could produce adrenaline in the body, leading the examiner to infer that the respondent is trying to deceive the machine. There is evidence to indicate that people from different ethnic groups also exhibit different stress reactions that may affect the test results.
There are three significant variables that can affect the accuracy of a test – the expertise of the examiner; the mental and physical condition of the person sitting the test; and the setting in which the test takes place. Independent studies give polygraphs a relatively high rating for reliability and accuracy, but these studies have also shown that only one in three who fail a test might, in fact, be guilty, which means that two out of three people who are found guilty are actually innocent. Even if the accuracy levels are 80 to 90 per cent, there is still a 10 to 20 per cent chance that an innocent person will fail a test and be found guilty. In addition, techniques which can be used to beat the test are available on the Internet.
The examiner is the single most important unknown in assessing the reliability and accuracy of polygraph tests. A large number of South African examiners have been trained in the United States or Israel, with experience in law enforcement but little experience of human psychology. Many examiners belong to the American Polygraph Association and might also belong either to the Polygraph Association of South Africa or to the SA Professional Polygraph Association. Neither of these South African associations is a statutory body and there is no facility in South Africa to assess or accredit examiners.
Because of the potential for error, our courts and arbitrators treat test results with some suspicion. At arbitration hearings, you will probably have to call the examiner as an expert witness so that they can testify and be cross-examined as to their expertise and test procedures and the arbitrator can examine and assess the reliability and accuracy of the test results. In cases of dismissal, the onus rests on the employer to prove that the dismissal was for a fair reason. A failed polygraph test or a refusal to participate in a test is not proof by itself of an employee’s guilt and is unlikely to convince an arbitrator, so corroborating evidence will be required.
Apart from concerns about reliability, accuracy and the expertise of the examiner, there are also constitutional issues with polygraph tests, such as the individual’s right to privacy and the right to be protected from self-incrimination. It is possible for a polygraph test to infringe one or more of these rights, but it is standard practice for examiners to brief the person regarding his or her rights prior to conducting a test, in which case there will presumably be no constitutional infringement.
Useful in investigations
Polygraph tests are more helpful and less controversial when used during an investigation and could provide an opportunity for volunteers to clear their names. Tests could reduce the number of suspects and might encourage the guilty person to confess, which is more reliable and useful as evidence than a failed polygraph test.
A failed test is not proof
Refusal to participate in a test might arouse suspicion but does not prove that a person has something to hide. Likewise, a failed test may well create suspicion, but is not proof that an offence was committed or that the employee is lying. Suspicion is one thing – proving guilt is something else.