Polygraph FAQs and Figures

You have been asked to take a polygraph test. For the vast majority of people, polygraph testing is a new and often frightening experience. We prepared the following information sheet to help you prepare for the test and to answer frequently asked questions.

1. What is a Polygraph?

   The polygraph is a scientific instrument designed specifically to record physiological changes that occur in the human body. The examiner looks for those changes consistent with deception and forms an opinion about your truthfulness.

2. What does the Polygraph record?

   Your polygraph test will be given using an Axciton Computerized Polygraph. During the polygraph test we will record your respirations, the ability of your skin to conduct electricity (EDA), cardio vascular activity and monitor you for occult body movements.

3. How does a Polygraph work?

   The Polygraph records physiological changes that occur in the human body. These changes are evaluated based upon changes that occur when questions are asked. Most of us can remember a time when we lied to our parents or other significant person. We could feel the changes in our bodies. Often we can feel our heart racing, palms sweating, and other symptoms of apprehension. When we evaluate the polygraph charts, we can see up to 32 different physiological changes indicative of lying. Lying makes us feel completely different from just being nervous.

4. How are these recordings made?

   The recordings of your respiration patterns are accomplished using two strain gauges, one across the chest and the other across the abdomen. The ability of your skin to conduct electricity is recorded by placing two electrodes on the fingers or using electrode pads on your palm. Cardio Vascular activity is recorded using a standard blood pressure cuff placed on either the forearm or upper arm.

5. Will the test hurt?

   The test is painless. There is no electricity, bright lights, bells or whistles. The only thing felt during the polygraph test is the blood pressure cuff. When your blood pressure is taken by a doctor, the cuff is inflated to approximately 200 mm hg. The polygraph examiner will inflate the cuff to approximately 70 mm hg. As the test progresses, the cuff may feel tight however the cuff is only inflated for three (3) to four (4) minutes. The fingers may tingle but the discomfort is transitory.

6. Are there different types of “lie detectors?”

   There are several types of polygraphs on the market today. Each instrument records the same basic psychophysiological data as described above. The actual recording may be made using ink and paper or by a computer.

   There are those who claim to detect lying using “voice stress.” It is important to know that every scientific research project assessing the “voice stress” technology has found the test to be accurate between 47% and 52% of the time. Voice Stress is not used by any of our National Security Agencies including, the CIA, NSA, and FBI, etc. Substantial research has been done by the Department of Defense to assess the reliability of “voice stress.” No Department of Defense Agency uses “voice stress.” The scientific community does not recognize “voice stress” as a reliable way to detect truth or deception. In 1989, the Congress prohibited businesses from using “voice stress” to test applicants or employees. Substantial penalties exist for violations of the ban.

7. How accurate are polygraph tests?

   There have been more than 100 published scientific studies of the accuracy of polygraph testing. The overall accuracy of a properly administered polygraph test is between 90% and 95%.

8. What will happen during the actual polygraph test?

   When you first meet with the examiner he will lead you to the polygraph room. The terms and conditions of the test will be explained and you will be asked to sign a statement indicating you understand and accept the terms and conditions for testing.

   The examiner will then collect basic data about you and the purpose of the test. Questions about health and substance abuse may be asked. These questions help the examiner to determine if any health problems exist that could have an adverse impact on the testing process.

   Once the preliminary questions have been asked and information obtained, you and the examiner will then discuss the matter under investigation. During this part of the test, you are given the opportunity to explain what you know about the matter under investigation. You and the examiner will discuss the allegations (specific issue testing) or your background (pre-employment testing).

   After discussing the matter under investigation, you and the examiner will discuss questions to be asked during the data collection process. You will be informed of the exact wording of each and every question to be asked during the test. If you are not told what questions are going to be asked, you should not take the test. If you are asked questions that were not reviewed, you should stop the test and leave the polygraph room.