FAQ: What does a polygraph measure?

A standard polygraph instrument 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 examinee 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.

FAQ: Is it possible to beat a polygraph?

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 them. 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.

Most examiners are now using "countermeasures detection" equipment which easily identifies anyone attempting to use the techniques taught by some web sites and government agencies. Unfortunately, many honest people are found "deceptive" to the test questions after attempting to use these techniques simply because they attempted to influence their test results. When an examiner discovers that the examinee is doing things to affect the charts, the result is either "deception indicated" or "inconclusive." In other words, a person will not pass a polygraph by using these techniques. In fact, recent research (2008-2009) has determined that in most cases when someone attempts to use the techniques taught on the internet to "beat" a polygraph, their test results actually GET WORSE (their scores indicate greater deception than if they had done nothing). 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.

FAQ: Can a pathological or compulsive liar beat the polygraph?

No. Compulsive liars may not be able to stop telling lies, but they absolutely know when they are telling a lie. As long as the person being tested knows what reality is, the polygraph will work fine.

FAQ: Are polygraph results admissible in court?

Polygraph results are admissible in many courts, but the final decision usually rests with the individual judge or arbitrator. Civil courts are more likely to admit polygraph evidence than criminal courts. If you intend to use polygraph results as evidence, you should select an examiner who has testified and been approved as an "expert."

Some judges will require a "Daubert" hearing to determine the admissibility of scientific evidence on a case-by-case basis. As time goes on, more and more jurisdictions are tending toward accepting polygraph evidence.

If the polygraph results are to be used in a legal proceeding, you must use the most accurate and scientifically validated method available. This requires that only a "specific issue" format be used covering one item only per test. Other formats (such as multiple issue tests) do not have the accuracy levels needed to be used as evidence.