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The Polygraph and Lie Detection
Psychological Set and Related Theories
Psychological set theory (e.g., Barland, 1981) holds that when a person being examined fears punishment or anticipates serious consequences should he or she fail to deceive, such fear or anticipation produces a measurable physiological reaction (e.g., elevation of pulse, respiration, or blood pressure, or electrodermal activity) if the person answers deceptively. A variation on this theory, the threat-of-punishment theory (Davis, 1961), posits that lying is an avoidance reaction with considerably less than 100 percent chance of success, but the only one with any chance of success at all. If a person anticipates there is a good likelihood and serious consequences of being caught in the lie, then the threat of punishment when the person tries to deceive will be associated with a large physiological response. Because the consequences of lying to the comparison questions are thought to be less than lying to the relevant questions, the theory is that lying to relevant questions will be associated with larger physiological responses than lying to control questions. These theories suggest that the detection of deception will be more robust in real-life situations involving strong emotions and punishment than in innocuous interrogations or laboratory simulations. In another variation of this theory, Gustafson and Orne (1963) suggest that an individual’s motivation to succeed in the detection task will be greater in real-life settings (because the consequences of failing to deceive are grave), and this elevated motivational state will also produce elevated autonomic activation.
This theoretical argument also leaves open significant possibilities for misinterpretation of the polygraph results of certain examinees. It is plausible, for instance, that a belief that one might be wrongly accused of deceptive answers to relevant questions—or the experience of actually being wrongly accused of a deceptive answer to a relevant question— might produce large and repeatable physiological responses to relevant questions in nondeceptive examinees that mimic the responses of deceptive ones.
The related arousal theory holds that detection occurs because of the differential arousal value of the various stimuli, regardless of whether or not there is associated fear, guilt, or emotion (Ben-Shakhar, Lieblich, and Kugelmass, 1970; Prokasy and Raskin, 1973). The card test illustrates this theory. The card test is an information test in which an examinee selects one item from a set of matched items (e.g., a card from a deck). This item produces a different response from the others, whether the examinee denies special knowledge about any of the items (i.e., lies about the selected item) or claims special knowledge about all of the items (i.e., lies about all but the selected item) (Kugelmass, Lieblich, and Bergman, 1967).