placebo on the electrodermal detection of deception, using a concealed information task with examiners blind to drug condition. The results indicated that the drugs had no effect. O’Toole et al. (1994) studied the effect of alcohol intoxication at the time of the mock crime on the detection of deception in a concealed information task. Intoxication at the time of the mock crime had no significant effect on the detection of deception though it did affect memory for crime details. Bradley and Ainsworth (1984), however, found that alcohol intoxication at the time of a mock crime reduced the accuracy of detection.

Overall, there has been little research on the effect of drugs on the detection of deception. The subjects tested have been exclusively undergraduates, dose-response effects have not been evaluated, and the mock crimes have been highly artificial with no consequence for detection. The weight of the published evidence suggests little or no drug effects on the detection of deception using the concealed information test, but given the few studies performed, the few drugs tested, and the analogue nature of the evidence, a conclusion that drugs do not affect polygraph validity would be premature.


Perhaps the most serious potential problem with the practical use of the polygraph is the possibility that examinees—particularly deceptive ones—might be able to decrease the test’s accuracy by engaging in certain behaviors, countermeasures, designed to produce nondeceptive test results. A wide range of potential countermeasures has been suggested (Krapohl, 1995, presents a taxonomy), and the effectiveness of some of these countermeasures has been examined in the empirical literature. Major classes of countermeasures include using drugs and alcohol to dampen polygraph responses (Cail-Sirota and Lieberman, 1995), mental countermeasures (e.g., relaxation, production of emotional imagery, mental disassociation, counting backwards, hypnotic suggestion, and attention-focusing techniques), and physical countermeasures (e.g., breath control, behaviors that produce pain before or during questioning, such as biting one’s tongue, or behaviors that produce muscle tension before or during questioning, such as pressing one’s toe to the floor or contracting a variety of muscles in the body). Advice about how to use countermeasures to “beat” the polygraph is readily available (e.g., Maschke and Scalabrini, no date; Williams, 1996) and there is anecdotal evidence of increasing levels of countermeasure use in federal security screening programs.

Countermeasures have long been recognized as a distinct threat to the validity and utility of the polygraph (U.S. Office of Technology As-

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