Effects of countermeasures on the control-question polygraph test were examined in an experiment with 120 Ss recruited from the general community. Ss were given polygraph tests by an examiner who used field techniques. Twenty Ss were innocent, and of the 100 guilty Ss, 80 were trained in the use of either a physical countermeasure (biting the tongue or pressing the toes to the floor) or a mental countermeasure (counting backward by 7) to be applied while control questions were being presented during their examinations. The mental and physical countermeasures were equally effective: Each enabled approximately 50% of the Ss to defeat the polygraph test. The strongest countermeasure effects were observed in the cardiovascular measures. Moreover, the countermeasures were difficult to detect either instrumentally or through observation.

Despite a long-standing controversy regarding their validity (e.g., Lykken, 1981; Raskin, 1989), physiological detection of deception (polygraph) tests are widely used in law enforcement (Raskin, 1989), are sometimes used in the courts (Honts & Perry, 1992; Morris, 1989), and play a major and increasing role in the national security systems of a number of countries (Barland, 1988; Honts, 1991). The use of polygraph tests for national security screening in the U.S. Department of Defense rose 586% between 1986 and 1990 (U.S. Department of Defense [DOD], 1987, 1991). Vital decisions concerning who should have access to cryptology, government secrets, and nuclear command and control have largely been based on polygraph test results. Although evidence has indicated that polygraph tests may be ineffective in national security screening systems (Honts, 1991, 1992), current proposals would greatly expand the use of polygraph screening to include all people with top secret security clearances and people involved in the war on drugs (DOD, 1991).

Control question tests (CQTs) are the most commonly used polygraph tests in law enforcement (Raskin, 1986) and they are widely applied within the national security system of the United States...