Spot On Polygraph


Get to Know Before Choosing


What Is a Polygraph & How It Works?

A polygraph is a scientific instrument used to detect deception. It simultaneously and continuously measures breathing patterns, relative changes in blood volume and Electro Dermal Activity (Changes in sweat).

The term "polygraph" literally means "many writings." The name refers to the manner in which selected physiological activities are simultaneously recorded.

What procedures are followed during a polygraph?
  • It is important to understand what a polygraph examination entails. A polygraph instrument will collect physiological data from at least three systems in the human body. Convoluted rubber tubes that are placed over the examinee's chest and abdominal area will record respiratory activity. Two small metal plates, attached to the fingers, will record sweat gland activity, and a blood pressure cuff, or similar device will record cardiovascular activity.
  • Up to date polygraph examiners will use a computerized polygraph instrument.
  • A typical polygraph examination will include the following 3 procedures/periods referred to as a pre-test, a chart collection phase and a test data analysis phase.
  • In the pre-test, the polygraph examiner will complete required paperwork and talk with the examinee about the test. During this period, the examiner will explain the instrumentation that is to be used and also discuss the questions that will be asked and familiarize the examinee with the testing procedure.
  • During this phase of the test the examiner will also establish whether or not the examinee is suitable to undergo a polygraph examination i.e. Medical and mental history.
  • During the chart collection phase, the examiner will administer and collect a number of polygraph charts. Following this, the examiner will analyze 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.
How accurate are the polygraph?
Can a person be forced to take a polygraph examination?
Can nervousness affect the examination results?
How confidential is a polygraph examination?
Does a polygraph detect lies?
Arranging polygraph testing