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