• Considering such mechanisms, how can the test procedure minimize the chances of false negative results?

  • Are the mechanisms relating deception to physiological responses universal for all people who might be examined, or do they operate differently in different kinds of people or in different situations? Is it possible that measured physiological responses do not always have the same meaning or that a test that works for some kinds of examinees or situations will fail with others?

  • How might the test results be affected by the examinee’s personality or frame of mind? For example, can recent stress change the likelihood that an examinee will be judged deceptive?

  • How might expectancies and personal interactions between an examiner and an examinee affect the reliability and validity of the physiological measurements? For example, might a test result have been different if a different examiner had given the test?

  • How might the wording or presentation of the relevant or comparison questions affect an examinee’s differential physiological responses? For example, if a test procedure gives the examiner latitude in formulating relevant or comparison questions, might the test results be affected by the particular questions that are used?

  • Which theory of psychophysiological detection of deception has the strongest scientific support? Which testing procedures are most consistent with this theory?

These questions are central to developing an approach to the psychophysiological detection of deception that is scientifically justified and that deserves the confidence of decision makers. Although many of the questions are in the realms of basic science in psychology, physiology, and measurement, answering them also has major practical importance. For example, a well-supported theory of the physiological detection of deception can clarify how much latitude, if any, examiners can be given in question construction without undermining the validity of the test. It may also specify countermeasures by which an examinee can act intentionally to create false readings that lead to misinterpretations of polygraph results and thus can help examiners anticipate their use and develop counterstrategies. Research focused only on establishing accuracy does not provide an adequate basis for confidence in a test because it inevitably leaves many critical questions unanswered. Consider, for example, some inherent limitations of a standard research approach in which some individuals are asked to lie about a mock crime they have committed and the polygraph is used to distinguish those examinees from others who have only witnessed the mock crime or who have no knowledge of it. If the polygraph performs well in this experiment, one can only



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