Mental and physical countermeasures reduce the accuracy of the concealed knowledge test |
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Authors: | Charles R. Honts Mary K. Devitt Marcus Winbush John C. Kircher |
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Affiliation: | Psychology Department, University of North Dakota, Grand Forks, USA;Educational Psychology Department, University of Utah, Salt Lake City, USA |
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Abstract: | The effects of a physical (pressing the toes to the floor) and a mental (counting backward by sevens) countermeasure on the concealed knowledge test (CKT) were examined in a mock crime experiment with 40 subjects. Some knowledgeable subjects were informed about the nature of the CKT and were trained in the use of a countermeasure, whereas others remained uninformed. All subjects were offered a monetary reward if they could produce a truthful outcome. Subjects were tested using standard field techniques and instrumentation. The physical and, to a lesser extent, the mental countermeasures reduced the accuracy of the CKT. These results clearly demonstrate that the CKT has no special immunity to the effects of countermeasures. |
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Keywords: | Lie detection Concealed knowledge test Guilty knowledge test Countermeasures Statistical decision making |
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