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The Polygraph and Lie Detection
one). The polygraph’s validity would be indicated by the degree to which it uncovered truth more accurately than the bogus pipeline comparison. Such a comparison might be particularly useful for examining issues of utility, such as the claimed ability of the polygraph to elicit admissions and confessions. These admissions and confessions might be appropriately attributed to the validity of the polygraph if it produced more true admissions and confessions than a bogus pipeline comparison condition. However, if similar proportions of deceptive individuals could be induced to admit transgressions when connected to an inert machine as when connected to a polygraph, their admissions could not be counted as evidence of the validity of the polygraph.
We believe that such a comparison condition is an appropriate reference point for judging the validity of polygraph testing, especially as that validity contributes to admissions and confessions during the polygraph interview. However, we have found no research attempting to assess polygraph validity by making this kind of comparison. This gap in knowledge may not present a serious threat to the quality of laboratory-based polygraph research, in which examinees normally do not admit their mock crimes, but it is important for making judgments about whether research on polygraph use under field conditions provides convincing evidence of criterion validity.
Validity and Utility
The appropriate criteria for judging the validity of a polygraph test are different for event-specific and for employee or preemployment screening applications. The practical value of a polygraph testing and scoring system with any given level of accuracy also depends on the application because in these different applications, false positive and false negative errors differ both in frequency and in cost.
No clear consensus exists on what polygraphs are intended to measure in the context of federal employee security screening.
Evidence of the utility of polygraph testing, such as its possible effects of deterring potential spies from employment or increasing the frequency of admissions of target activities, is relevant to polygraph validity only under very restricted circumstances. This is true in part because any technique that examinees believe to be a valid test of deception is likely to produce deterrence and admissions, whether or not it is in fact valid.