the likelihood that with polygraph screening programs such as are being operated at both DOE and FBI, which yield a very low proportion of negative results, the majority of spies are likely to “pass” at least one polygraph test without being detected, even if they do not use countermeasures. Thus, as we note above, a policy of screening that may be justified on the basis of utility for deterrence and elicitation of admissions cannot be counted on to detect more than a small proportion of major security violators.

Federal officials need to be careful not to draw the wrong conclusions from negative polygraph test results. Our discussions with polygraph program and counterintelligence officials in several federal agencies suggest that there is a widespread belief in this community that someone who “passes” the polygraph is “cleared” of suspicion. Acting on such a belief with the results of security screening polygraph tests could pose a danger to national security because a negative polygraph test result in a population with a low base rate, especially when the test protocol produces a very small percentage of positive test results, provides little information on deceptiveness beyond what was already known prior to the test, that the probability of true transgression is very low.


Although the scientific base for detecting deception remains weak, scientific analysis remains the best way for government agencies to assess techniques that are presented as useful for detecting and deterring criminals and national security threats and to develop improved methods. This section suggests ways that federal agencies should evaluate purported techniques for detection of deception or of concealed information. The next section recommends a program of research aimed at improving the capability for detection and deterrence.

Evaluating Methods for Detecting Deception

Need for Scientific Evaluation Techniques for detecting deception should be subjected to independent scientific evaluation before any agency relies on them. Government agencies will continue to seek accurate ways to detect deception by criminals, spies, terrorists, and others who threaten public safety and security interests. These agencies need to be able to make objective evaluations of new techniques offered to them by entrepreneurs who claim that these techniques are based on science. Recent experience suggests that many such techniques are likely to be developed in the coming years and that many of them will be oversold. In particular, proponents are likely to present evidence that a technique discriminates

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