Description of a Lie Detector

Polygraph tests are sometimes used to uncover evidence.

Polygraph tests, also known as lie detectors, are devices that examine physiological data in an attempt to determine whether someone is telling a lie. Although polygraph tests are highly controversial, they have been used in many settings.

Meaning

The word "polygraph" literally translates to "many writings." The name reflects the several ways in which polygraphs record physiological data.

How It Works

Polygraph instruments collect data about respiratory, sweat gland and cardiovascular activity.

Polygraph Examinations

Polygraph examinations involve three sections: a pre-test, a chart collection and a test data analysis. Pre-testing includes equipment setup and an explanation of the process. The chart collection phase involves the questioning of the patient. The patient's responses are analyzed in the last section.

Function

Polygraph tests are used by law enforcement agencies, the legal community and businesses.

Criticism

Critics of polygraph tests assert that they are unfair, can be manipulated and do not always produce accurate results. As a 2003 Committee on National Statistics study pointed out, "Factors other than truthfulness that affect the physiological responses being measured can vary substantially across settings in which polygraph tests are used."

References

• The National Academies Press
• American Polygraph Association: FAQ
• Polygraph Place: FAQ