What is a Polygraph Test?
A Polygraph test takes between 2 to 3 hours and consists of three phases; a pre-test interview, collection of charts, and analysis of charts. Polygraph tests are the most fool proof method of testing if someone is being deceptive.
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. This stage is normally the longest to complete, and will take anywhere between 45 and 90 minutes.
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 analyze the results before giving a decision as to the subjects truthfulness or deception to the given issue.
Will I know the questions to be asked on the polygraph examination?
Yes! The examiner will construct questions from the information given by you to cover the specific issue. He will review the questions with you and make any changes to the questions to ensure that you both agree. All the questions will meet the strict rules for the latest polygraph techniques in accordance with the APA.
All questions are discussed with the subject thoroughly before the test commences and will be answered with a "yes" or "no" answer only.
How Does the Polygraph Work?
The polygraph 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 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 convoluted rubber pneumograph tubes are placed around the subject's upper chest and abdomen on the outside of their clothing, these record respiration 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 Polygraph Testing?
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.
