NCJ Number
194887
Journal
International Journal of Police Science and Management Volume: 4 Issue: 1 Dated: Spring 2002 Pages: 16-27
Date Published
2002
Length
12 pages
Annotation
This article discusses the two methods of psychophysiological detection of deception in field practice: the guilty knowledge test (GKT) and the control question test (CQT).
Abstract
The CQT consists of neutral, relevant, and control questions. The neutral questions are general and unrelated to the crime. The relevant questions are specific to the crime. The control questions are designed to be unrelated to the crime under investigation, but are assumed to elicit at least as much emotion as the relevant questions do for an innocent suspect. If the psychophysiological responses are generally greater to the relevant questions than to the control questions, then the examinee is considered to be deception on the relevant questions, and is assumed to be guilty of the crime. The GKT consists of a series of multiple-choice questions, each having one critical alternative and several neutral, noncritical alternatives. An examinee is required to deny each alternative. If the person’s psychophysiological responses to the several critical alternatives are consistently larger than to the neutral alternatives, knowledge about the event in question is inferred. GKT attempts to detect not lying, but the presence of guilty knowledge. A survey carried out by members of the American Psychological Association and the Society for Psychophysiological Research proved that many of the members considered that the GKT was superior to the CQT in its validity. The GKT has been the main method of polygraphic examination by the Japanese police since the 1950's. The use of the GKT in Japan is described in the hope that polygraphers and researchers worldwide will recognize its validity as a scientifically based method of uncovering facts in forensic investigations. 2 figures, 1 table, 30 references