title: Mental and physical countermeasures reduce the accuracy of the concealed knowledge test.
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.
authors.affiliation: Psychology Department, University of North Dakota, Grand Forks, USA.
authors.forename: C R
authors.initials: CR
authors.lastname: Honts
authors.forename: M K
authors.initials: MK
authors.lastname: Devitt
authors.forename: M
authors.initials: M
authors.lastname: Winbush
authors.forename: J C
authors.initials: JC
authors.lastname: Kircher
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008014:Lie Detection / Q000523:psychology*; D008297:Male; D008606:Mental Processes / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*