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A Polygraph test normally takes around one and a half hours from beginning to end with three different phases; pre-test interview, collection of charts, and Post test interview. Our examiners will explain the test process in detail before starting. We understand anyone taking a test will be nervous and we will explain to you how this will not effect the test results.

Pre-test interview & formulation of questions

During the pre-test interview the examiner will explain how the polygraph works, discuss the issue and develop and review all questions to be asked on the polygraph test.

Collection of Charts-

During this phase the subject will be attached to the polygraph. The set of questions which were developed during the pre-test interview will be asked several times.

Analysis of Charts-

Once the examiner has conducted the test he will analyse the results before giving a decision as to the result of the test.

What Questions Can be Asked?

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.

All questions are discussed thoroughly before the test commences and will be answered "yes" or "no".

How Does the Polygraph Work?

Click here: to see an explanation of how the Polygraph works?

The polygraph works by tracing changes in a persons physiological conditioning during questioning. These changes are recorded directly on to the polygraph charts in order that they can be reviewed. Some of the changes that occur may replicate those that have been linked with truth or deception for many years. These physiological changes have been the subject of various research projects and our examiners have undertaken many hours of polygraph chart analysis instruction to interpret them.

The Polygraph charts are generated by attaching various components to the subject.


Two rubber tubes are placed around the subjects upper chest and abdomen on the outside of their clothing, these record breathing and movement.


The GSR (sweat gland activity) is produced by placing two finger plates across fingers on one of the subjects hands. These trace changes to the skin response during the examination.


This component traces changes to the subjects relative blood pressure and pulse rate and it is similar to the pressure cuff your doctor uses when taking your blood pressure.

After the questions have been asked with the subject attached to the polygraph the examiner will read the generated charts to establish truth or deception. The agreed questions will always be asked on several occasions.

How reliable is Polygraph Testing?

The polygraph is 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, you can view further information at their web site

Click here to view the 2011 meta analysis related to polygraph validity.


At UK Lie Tests, we specialise in Polygraph lie Detector Testing.