results. Moreover, most polygraph testing procedures allow for uncontrolled variation in test administration (e.g., creation of the emotional climate, selecting questions) that can be expected to result in variations in accuracy and that limit the level of accuracy that can be consistently achieved.

Theoretical Basis The theoretical rationale for the polygraph is quite weak, especially in terms of differential fear, arousal, or other emotional states that are triggered in response to relevant or comparison questions. We have not found any serious effort at construct validation of polygraph testing.

Research Progress Research on the polygraph has not progressed over time in the manner of a typical scientific field. It has not accumulated knowledge or strengthened its scientific underpinnings in any significant manner. Polygraph research has proceeded in relative isolation from related fields of basic science and has benefited little from conceptual, theoretical, and technological advances in those fields that are relevant to the psychophysiological detection of deception.

Future Potential The inherent ambiguity of the physiological measures used in the polygraph suggest that further investments in improving polygraph technique and interpretation will bring only modest improvements in accuracy.

Evidence of Polygraph Accuracy

Source of Evidence The evidence for polygraph validity lies primarily in atheoretical, empirical studies showing associations between summary scores derived from polygraph measures and independent indicators of truth or deception, in short, in studies that estimate the accuracy of polygraph tests. Accuracy—the ability to distinguish deceptive from truthful individuals or responses—is an empirical property of a test procedure administered under specific conditions and with specific examinees. Consequently, it may vary with a number of factors, such as the population of examinees, characteristics of individual examinees or examiners, relationships established in the interview, testing methods, and the use of countermeasures. Despite efforts to create standardized polygraph testing procedures, each test with each individual has significant unique features.

Realism of Evidence The research on polygraph accuracy fails in important ways to reflect critical aspects of field polygraph testing, even for specific-incident investigation. In the laboratory studies focused on specific incidents using mock crimes, the consequences associated with lying or being judged deceptive almost never mirror the seriousness of those in real-



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