Polygraph-How it works!

HOW IT WORKS

A polygraph instrument is basically a combination of medical devices that are used to monitor changes occurring in the body. As a person is questioned about a certain event or incident, the examiner looks to see how the person's heart rate, blood pressure, respiratory rate and electro-dermal activity (sweatiness, in this case of the fingers) change in comparison to normal levels. Fluctuations may indicate that person is being deceptive, but exam results are open to interpretation by the examiner.

Polygraph exams are most often associated with criminal investigations, but there are other instances in which they are used. You may one day be subject to a polygraph exam before being hired for a job: Many government entities, and some private-sector employers, will require or ask you to undergo a polygraph exam prior to employment.

Polygraph examinations are designed to look for significant involuntary responses going on in a person's body when that person is subjected to stress, such as the stress associated with deception. The exams are not able to specifically detect if a person is lying, according to polygrapher Dr. Bob Lee, former executive director of operations at Axciton Systems, a manufacturer of polygraph instruments. But there are certain physiological responses that most of us undergo when attempting to deceive another person. By asking questions about a particular issue under investigation and examining a subject's physiological reactions to those questions, a polygraph examiner can determine if deceptive behavior is being demonstrated.

How does the test process work?

a: The examiner receives and reviews the facts surrounding the case.

b: The examiner explains the test process to the subject and reviews the case facts during the pretest interview.

c: The examiner designs the specific test questions and reads each question to the subject to make sure each one is easily understood.

d: The test subject is attached to the polygraph instrument and given additional instructions.

e: The questions are read to the subject several times while he/she is attached to the polygraph sensors.

f: After all charts (polygrams) have been run, the examiner analyzes the charts and develops a numerical score for the test. This score results in a conclusion of either truthful, deceptive or inconclusive.

g: The examiner will transmit the test results to the client verbally, usually within 24 hours. A written report may be requested, however some examiners will charge a small fee for this report.

NOTE: Polygraph exams are conducted in private with no other persons permitted in the examination room during the test (other than possibly an interpreter). NOTE: The average polygraph exam takes from one to three hours to complete.

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