The Polygraph which is often referred to as a “Lie Detector” is an instrument that records physiological reactions caused by the autonomic nervous system. A polygraph examination is a combination of both a psychophysiological testing technique and an interview. The instrument itself is a combination of several recording devices routinely used in the medical and scientific community and it records the physiological changes responses which occur when the subject is asked questions during the test. The polygraph records respiration, cardiovascular activity and electro dermal activity.

Undoubtedly polygraph testing is very accurate when the examiner is properly qualified and is using the latest computerised equipment. There are a number of different polygraph techniques or tests and the examiner should always use the one which is most accurate and best suited to the issue under investigation. There is no one single figure to sum up the accuracy of polygraph tests as there are a numbers of factors which affect accuracy. Please see our article How accurate can I expect a Polygraph test to be? for more information on this topic.

There is no doubt that the polygraph is highly reliable, providing the person using it is properly trained and the technique they use is validated. The American Polygraph Association (APA) has gathered over 200 studies on the subject. Based on twelve separate studies involving 2174 actual cases since 1980, evidence suggests that qualified polygraph examiners are 98% accurate in their overall decisions.

A polygraph test will take a minimum of 1.5hours but may take up to three hours. The test comprises of a number of unbiased and objective phases:

  • The first phase is the pre-test interview, which includes; obtaining a statement of consent to conduct the test; the completion of a medical questionnaire; an explanation of the equipment; obtaining background data from the examinee and their version of events. During this period, the examiner will discuss the questions to be asked and familiarize the examinee with the testing procedure All test questions are thoroughly reviewed giving the examinee an opportunity to qualify or explain any of their answers
  • The next phase is the collection of data and initially consists of the attaching of the components which routinely includes breathing tubes which are attached around the examinee upper and lower chest area. These tubes record breathing rate, breathing volume and breathing pattern. A standard blood pressure cuff is attached to the examinees upper arm and is inflated to a light pressure immediately prior to the commencement of the test, to record a constant reading of the examinees heart rate and pulse rate; the pressure is then released at the end of the test. Electrodermal activity finger cuffs are attached to two fingers to measure skin conductance (sweat gland activity) and a photo-plethysmograph is attached to another finger to measure blood rate volume. The examinee will be seated on a sensor movement mat. Following this, the examiner will analyse the charts and render an opinion as to the truthfulness of the person taking the test. The examiner, when appropriate, will offer the examinee an opportunity to explain physiological responses in relation to one or more questions asked during the test. It is important to note that a polygraph does not include the analysis of physiology associated with the voice. Instruments that claim to record voice stress are not polygraphs and have not been shown to have scientific support
  • Chart analysis and post-test interview

The result is available at the end of the examination.

Being nervous and anxious before a polygraph exam is common and not unusual. It is also normal to worry about failing the test, even if you know you are being truthful. Being nervous doesn’t cause a person to fail a polygraph test, – lying does.

Provided that examiner conducting the test is trained and qualified it is highly improbable. The polygraph is a medical instrument that records changes in a person’s autonomic reactivity whilst they answer questions, and If a person engages in behaviours in order to distort the polygraph tracings, it becomes evident to a trained examiner when he sees the tracings.

In most cases it is easy for a qualified examiner to determine if an examinee is attempting to alter the outcome of a test. When such behaviour is identified, a result of “purposeful non cooperation” is given.

Polygraph tests are not intended to be a means for delivering a legal verdict, this is the role of the courts and juries. However there is no reason why the results of a polygraph test cannot be submitted as evidence, the judge will decide in each case whether to allow this evidence to be admitted. The polygraph is no different in many ways to other machines such as x-rays, electrocardiographs etc. whose results are admitted in evidence but interpretation is required by the expert. Whether the results are used in court or not, polygraph testing has saved investigators and companies huge amounts in investigative costs and resources by narrowing the focus of enquiry and providing further investigative leads.

Ensure the examiner was professionally trained at a polygraph school accredited by the American Polygraph Association and has since undertaken regular ongoing training. They should use the latest computerised equipment and the latest validated techniques. Ensure that your examiner fulfils each of these requirements.
Additionally it is beneficial to look for a polygraph examiner who has professional affiliations and memberships with recognised associations that set professional standards for its members, such as the American Polygraph Association or the British Polygraph Association. Currently there is no Irish Polygraph Association.

It is vitally important that you only use an examiner who has been properly trained and is a member of an approved professional association such as the American Polygraph Association. All our examiners are members of numerous professional and recognised organisations including the American Polygraph Association and the British Polygraph Association. This can be independently verified on those associations websites. Therefore you can be assured that when you deal with Lie Detector Ltd your test will be conducted professionally and your examiner has been trained to the highest standards.

Yes, but the examiner must first have written consent of a parent or guardian. Most examiners will not test anyone under the age of 14 years, however this does not mean that all 14 years olds are good candidates for taking a test and this will need to be reviewed on a case by case basis.

The examiner will work with you to construct questions that cover the test issue as well as meeting the strict rules for the latest polygraph techniques

We conduct tests in Dublin and a number of other locations in both the Republic of Ireland and Northern Ireland. Please contact us to discuss your nearest test location.

The price can vary depending on the reason for the test. A non refundable part payment will be required at the time of booking.However our prices are the most competitive and are not inflated by additional fees to an agent or middle man. Ring us (01 685 4715) or email us:, advising the reason for the test and we confirm the price

No one can be forced to take a test and in fact the examiner will require you to give written consent to the examination. We would always urge you to carefully consider how the outcome of the test may affect you

To book a test just ring us on 01 685 4715

ABSOLUTELY NOT, any prescribed medication should be taken as normal. It is a dangerous myth that medication should be stopped. Before accepting an appointment, the examiner will discuss with the potential examinee their suitability to take a test. This will involve asking questions about their physical and mental health and any medications prescribed by the Doctor that the potential examinee is either taking or should be taking. Suddenly stopping medication without the Doctor approval is dangerous and in fact will be detrimental to a test as the health condition the potential examinee is suffering is likely to become unstable therefore making the person unsuitable to take a test which is likely to adversely affect the polygraph examination. Find further information here: Do Drugs Affect the Results of a Polygraph Test?