NCJ Number
186442
Journal
Journal of Forensic Psychology Practice Volume: 1 Issue: 1 Dated: 2001 Pages: 87-90
Date Published
2001
Length
4 pages
Annotation
This article reviews the two main approaches to psychophysiological credibility assessment (PCA), commonly known as polygraph testing, along with the techniques, scientific support and criticisms associated with each.
Abstract
The two major approaches to conducting PCA tests are knowledge-based and deception-based tests. All of the techniques involve instrumentally monitoring autonomic nervous system indexes. In knowledge tests, the subject is monitored to determine whether he/she responds differentially to details of the crime that are known only to the investigator and the person who committed the acts under investigation. This type of test assumes that the person who committed the crime will recognize the correct alternative and will respond to its presentation with a physiological orienting response. Innocent individuals, on the other hand, will have no reason to discriminate any one item from another and will produce physiological responses at random. Three problems plague this approach. Two have to do with designing the test and the third is a problem of application. The other popular approach to deception-based testing is represented by a family of techniques known as the comparison question tests (CQT). In a CQT a second set of questions unrelated to the acts at issue is developed so as to evoke physiological responses from innocent individuals. The rationale of the CQT approach views the relevant questions and the comparison questions as in competition with one another. If the relevant questions produce the larger responses, then the examiner concludes that the subject was attempting deception to the relevant questions. If the comparison questions produce the larger responses, then the examiner concludes that the subject was being truthful to the relevant questions of the examination. The available scientific data overwhelmingly support the validity of the CQT in both laboratory and field settings. 24 references.