My dad passed the polygraph test...Now mom lets see you take a polygraph test...I bet you will fails it because you a nothing but a manipulative liar!

How accurate is the polygraph?

U.S. Government studies have concluded that the single-issue (one question) polygraph exam, conducted properly by a qualified examiner, is 87 to 95 percent accurate. It is the most accurate tool available today for determining truth or deception. Accuracy of the multi-question exam drops to around 80 percent due to a number of psychological factors. These statistics do not include "inconclusive" results in which no opinion can be made from the polygraph charts, which happens about 20% of the time.

What does the polygraph record?

A standard polygraph records changes in blood pressure, pulse rate, pulse strength, galvanic skin reflex (sweat gland activity), and upper and lower breathing patterns. It does not matter if the subject is "nervous" during the testing process - that is to be expected. The polygraph records significant changes from the subject's "norm" when specific questions are asked. A person intending deception to a particular question will activate his/her Sympathetic Nervous System as a "self defense" mechanism when that question is asked on the test. The SNS activation will cause recognizable changes in one or more of the physical responses.

Can someone beat the test? (back to top)

The polygraph works by recording changes in a person's Sympathetic Nervous System, part of the Autonomic Nervous System, which operates independently of conscious thought. For example, your lungs and heart continue to operate even when you are asleep - you don't have to think about it. These systems can be consciously controlled only very slightly, and attempts to change these systems are usually picked up by the examiners, who are trained to identify such things. It is highly unlikely that someone can alter the outcome of a polygraph exam, but it is not impossible. A verified accuracy rate as high as 95% attests to this fact.

Use of certain drugs and medications can also affect the exam, but such use generally results in an "inconclusive" test. It is virtually impossible to change a result from "deceptive" to "truthful" through the use of drugs or medications prior to an exam. If drugs are suspected, a pre-test (or post-test) drug screening is advised.

Everything You Wanted To Know About Polygraphs!