Putting the Polygraph to the Test

The polygraph or "lie detector" test has long been used in American law enforcement, and has also found favor among private companies looking to screen employees. But research suggests that the polygraph test, while useful, is far from perfect.

Amherst, NY (PRWEB) December 26, 2004 -- The polygraph test-commonly known as the lie-detector test-is used by government agencies, law enforcement, and some private employers to help screen potential employees and catch wrongdoers. But the polygraph is not nearly as reliable as many people believe. In his article, "Exploring Controversies in the Art and Science of Polygraph Testing," psychology instructor John Ruscio examines the flaws of polygraph tests and how those flaws may be corrected.

Ruscio explains that there are "two pervasive myths" of polygraph tests: they are objective and they are infallible. Unfortunately, neither is true. A polygraph test consists of "a lengthy pretest interview during which the examiner gains access to a wealth of background information and formulates specific questions that are then used during the test phase, when physiological responses are recorded." The phrasing of the questions, the attitude of the subject, and the biases of the examiner can all affect the results.

There are two main types of polygraph tests: the control question test (CQT) and the guilty knowledge test (GKT). The control question test compares a subject's baseline responses to their responses to specific questions. This test is commonly used for screening employees. The guilty knowledge test presents the subject with multiple-choice questions to see if a specific answer (the true account of an event) provokes a greater response than the plausible alternatives. The GKT is primarily used to investigate crimes.

The Employee Polygraph Protection Act, passed in 1988, bars most private employers from using polygraphs to screen employees. But as Ruscio points out, "law enforcement, military, and government agencies were exempted from the prohibition on polygraph testing: A technique judged unsuitable for screening applicants to the local convenience store is still used to screen individuals responsible for maintaining our national security."

Ruscio suggests there are ways to improve polygraph testing. These include conducting more thorough studies into the accuracy of polygraphs, using the GKT more to solve crimes and the CQT less for general screening, and verifying the accuracy of confessions acquired through polygraphs.

"The advantage of eliciting confessions and damning admissions must be considered against disadvantages," he writes, "such as invasions of privacy, damages to employee morale, the cost of investigating large numbers of false-positive results and the accompanying harm that is done to qualified individuals' careers, the possibility that the most dangerous individuals may be likely to learn and effectively employ countermeasures, and the false sense of security that can stem from the use of a highly fallible screening tool."

Skeptical Inquirer is the official journal of the Committee for the Scientific Investigation of Claims of the Paranormal (CSICOP), a nonprofit scientific and educational organization founded in 1976 by Paul Kurtz, Isaac Asimov, Carl Sagan, and other prominent academics, scientists and writers. CSICOP encourages the critical investigation of paranormal and fringe-science claims from a responsible, scientific point of view.

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