A polygraph examination usually takes around 2 hours from beginning to end and consists of three different phases; pre-test interview, collection of charts, and analysis of charts.
- 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 3 or 4 times.
- Analysis of Charts-
Once the examiner has collected the charts he will analyse the results of the polygraph test before giving a decision as to the subject's truthfulness or deception to the given issue.
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 with the subject thoroughly before the test commences and will be answered with the reply "yes" or "no".
How Does the Polygraph Work?
The polygraph lie detector works by tracing changes in a person's 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 polygraph examiners have undertaken many hours of polygraph chart analysis instruction to interpret them.
The Polygraph charts are generated by attaching four components to the subject.
- Pneumograph -
Two rubber pneumograph tubes are placed around the subject's upper chest and abdomen on the outside of their clothing, these record breathing and movement.
- G.S.R -
The GSR or Galvanic Skin Response is produced by placing two finger plates across fingers on one of the subject's hands. These trace changes to the skin resistance during the examination.
- Cardiosphygmograph -
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 at least twice.
How reliable is the polygraph?
There is no doubt that the polygraph lie detection equipment used is highly reliable, providing the person using it is properly trained and the technique they use is validated.
If you would like to talk about your situation please call me, Bruce Burgess, on 01372 842 170
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