Lie Detector Tests

We Answer Your Frequently Asked Questions About Our Lie Detector Tests

Here at Nighthawk Polygraph, we often receive a slew curious queries about our line of work and available services. For some, polygraph examinations are best-known for how often they feature in crime novels, television programs, and movies. Lie detector tests are very real, however, and can be key forensic evidence contributors in settling a case. The application of these examinations is varied, and we have experience in matters ranging from marital distrust to white-collar crime. If you would like to know more about this fascinating field and how we can assist you, keep reading.

lie detection

What Are Lie Detector Tests and How Do They Work?

The word “polygraphy” means “many writings”, and this is in reference to the number of physiological reactions the detector machine itself records all at once. A polygraph examination is a collection of data on biological responses that have been documented while asking an examinee a series of questions. The test may involve some or all of the following equipment:

  • Electronic sensors placed across the chest and abdomen that record the respiration rate.
  • Adhesive electrodes attached to fingers that read electro-dermal activity (sweat glands producing sweat).
  • An arm cuff which measures cardiovascular activity such as blood pressure and heart rate.
  • There are also other devices in lie detector tests, such as a finger plethysmograph to measure blood volume in the finger as well as motion sensors.

During the test, the polygraphist asks the examinee a series of pre-discussed “yes” or “no” questions. The detector itself documents the examinee’s physiological responses to these questions. These responses are then compared to the responses of control questions that were charted before the test. Control questions allow the polygraphist to determine an initial baseline set of responses when the examinee is being truthful or instructed to lie. Elevated blood pressure, a quickening pulse, rapid and shallow breathing, and increased skin conduction due to sweating are all indications of deception.

Do Polygraphs Really Work?

Lie detector tests are highly accurate, but they work hand in hand with an expert examiner’s reading of the results. The results are important, but so is the person who interprets these results. This is why it is critical to partner with a polygraphist with experience and expert training, as cheaper or inexperienced examiners simply do not have the expertise required to see nuances in documented physiological responses. In South Africa, lie detector tests can be used in everything from labour disputes to disciplinary enquiries, and the CCMA often uses polygraph results as a forensic tool when gathering evidence on a case.

Is It Possible to Beat a Polygraph Test?

It is important to understand that polygraphs don’t lie – people do. Deceiving an unskilled examiner is possible, but it is extremely difficult to convince your own psychophysiological responses to behave a certain way without any abnormal data showing up on the test. An experienced examiner knows what it looks like when an examinee is attempting to regulate their responses, and they will usually be able to sniff out the truth from deception.

When it comes to the gold standard in polygraph testing, it doesn’t come more specialised than our services here at Nighthawk Polygraph. If you are seeking top industry expertise, feel free to get in touch with us today.

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