Polygraph is a generic name for an instrument which is commonly known as a 'Lie Detector'. Contrary to popular belief, it does not record directly whether a person is lying or telling the truth; it records changes which take place in the body during stress.
A Polygraph Instrument is, in effect, a sophisticated piece of medical equipment which measures autonomic nervous reactions which take place in the human body when an 'important', or incriminating, lie is told. These responses are usually not visible to the eye. The physiological reactions which occur when a person tells a lie are measured by recording respiration, cardio-vascular reaction and skin moisture changes.
Since the beginning of the twentieth century, the Polygraph has been widely used, particularly in the USA, by Governments and Law Enforcement Agencies - always with the full consent of the subject. Experts claim an accuracy of up to 99% in their findings and no other systems used for lie detection purposes have come close to the range of accuracy achieved by the Polygraph.
The Polygraph operator is usually known as the Examiner and the interviewee is known as the Subject.
All of our Consultant Examiners have been professionally trained at a Polygraph school accredited by the American Polygraph Association and have their certificates available at the time of examinations.
When Polygraph examinations are to be carried out, the Examiner is given a full briefing on the circumstances relating to the incident or situation. Each Subject is then interviewed in depth before a series of questions is discussed and agreed - trick questions are never inserted. Tests are confined to relevant questions for each situation and do not delve into the private lives of the subjects. The Subject is then connected to the apparatus by means of an arm-band, two finger sensors and two convoluted rubber tubes which encircle the chest and abdomen.
The agreed questions are then asked in sequence, the reactions of the Subject as the questions are asked and answered are recorded on a computer. The resultant chart can then be analyzed by the Polygraphist to detect truthfulness or deceit.
A Polygraph test takes 2 hours - usually longer - even though the Subject may only be connected to the apparatus for a few minutes whilst the agreed questions are asked and answered.
Each Polygraph examination is confidential and usually only the Examiner and the Subject are present during the actual test. However, it is acceptable to have another person present in certain situations (e.g. where the Subject is female and the Examiner is male, another female should also be in attendance).
One of the few commercial enterprises providing a Polygraph facility in the UK is Nationwide Investigations Group. Our work involving the Polygraph falls into three main categories:
- Pre-employment screening. To verify that information given to employers by potential employees is truthful.
- Honesty maintenance. A programme to help employers to contain and eliminate staff theft.
- Specific investigations. To identify the perpetrators of particular incidents, such as theft (of cash, property or information) and marital infidelity.
Nationwide Investigations Group emphasize that the Polygraph is often used to confirm innocence rather than to establish guilt. If a loss has occurred, pressure is inevitably imposed on innocent parties and the Polygraph can help to dispel the unpleasant aura of suspicion which can surround such an incident.
In conclusion, there is nothing threatening about the Polygraph which has been used with great effect for many years in the USA where it has become an accepted management tool. It is important to emphasize that:
- Every question is fully discussed prior to the commencement of the examination.
- All questions are incident related.
- The results of the examination are strictly confidential.
- All tests are voluntary.
Nationwide Investigations Group have been providing polygraph examinations (lie detector tests) for over 30 years. When we updated our equipment to state of the art computerised versions, Madame Tussaud's were keen to acquire one of our older models, as seen in the photograph with the Tony Blair waxwork, to display in their FBI section.