and organizational phenomena that go along with a ritual that has a mystique, a “priesthood,” and a set of secrets. One of these is the difficulty of gaining access to information. Some information of interest to this study, such as the polygraph test records of known spies, is classified for national security reasons. Other information, such as the precise ways particular pieces of polygraph equipment measure physiological responses, is guarded by equipment manufacturers as trade secrets. Some manufacturers ignored our requests for such information, even though we offered to sign legally binding promises of nondisclosure. Information about computer scoring algorithms for polygraph tests was similarly withheld by some algorithm developers. All of this behavior makes scientific analysis difficult. Some of these “secrets” probably have good practical justification, but they are also very much like the activities of a priesthood keeping its secrets in order to keep its power.

Another aspect of the polygraph mystique that creates difficulties for scientific analysis is the strong, apparently unshakeable, beliefs of many practitioners in its efficacy on the basis of their experiences. We have heard numerous anecdotes about admissions of serious crimes and security violations that have been elicited in polygraph examinations even after background checks and ordinary interviews had yielded nothing. Many of these admissions have been later corroborated by other convincing evidence, indicating that the polygraph examination sometimes reveals truths that might otherwise have remained concealed indefinitely. We do not doubt the veracity of these anecdotes. However, they do not constitute evidence that the polygraph instrument conveys information that, in the context of the polygraph test, accurately identifies the locus of deception. Rather, they signify that something in the polygraph examination can have this result. It may be the test, the interviewer’s skills, the examinee’s expectation of detection, or some combination of these or other factors. From a scientific standpoint, these anecdotes are compelling indications that there is a phenomenon in need of explanation; they do not, however, demonstrate that the polygraph test is a valid indicator of deception.

Practical Implications

From a practical standpoint, it can make a considerable difference whether decisions that rely on polygraph evidence are resting on a scientifically proven device and procedures (that is, on the test), on the judgments of examiners, or on the expectation that guilty examinees will be sufficiently fearful of detection to confess. For example, if the apparent successes depend only on examinees’ fear of detection and not on the test itself, the examination would fail with well-trained spies who know the test’s limitations and do not respond to the mystique.

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