U.S. armed services, for example, the introduction of random and frequent drug testing has been associated with lower levels of drug use.

Deterrence effects depend on beliefs about the polygraph, which are logically distinct from the validity of the polygraph. The deterrent value of polygraph testing is likely to be greater for individuals who believe than who do not believe in its validity for detecting deception.

It is worth noting that deterrence has costs as well as benefits for an organization that uses polygraph testing. The threat of polygraph testing may lead desirable job candidates to forgo applying or good employees to resign for fear of suffering the consequences of a false positive polygraph result. The more accurate people believe the test to be—independent of its actual validity—the greater the benefits of deterrence relative to the costs. This is because a test that is believed to be highly accurate in discriminating deception from truthfulness will be more deterring to people whose actions might require deception and more reassuring to others who would be truthful than a test that is believed to be only moderately accurate.

It is also worth emphasizing that validity and utility for deterrence, while logically separable, are related in practice. The utility of the polygraph depends on the beliefs about validity and about how results will be used among those who may be subject to testing. Utility increases to the extent that people believe the polygraph is a valid measure of deception and that deceptive readings will have severe negative consequences. To the extent people hold these beliefs, they are deterred from engaging in behaviors they believe the polygraph might detect. If people came to have an equal or greater level of faith in some other technique for the physiological detection of deception, it would acquire a deterrent value equal to or greater than that now pertaining to polygraph testing.

Eliciting Admissions and Confessions

Polygraph testing is used to facilitate interrogation (Davis, 1961). Polygraph proponents believe that individuals are more likely to disclose information about behaviors that will lead to their punishment or loss of a valued outcome if they believe that any attempts to conceal the information will fail. As part of the polygraph pretest interview, examinees are encouraged to disclose any such information so that they will “pass” the examination. It can be important to security organizations to have their employees admit to past or current transgressions that might not disqualify them from employment but that might be used against them, for example, by an enemy who might use the threat of reporting the transgression to blackmail the employee into spying. Anecdotes suggest that the polygraph context is effective for securing such admissions. As re-



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement