Does the strength of correspondence vary substantially across different test settings, questioning methods, study populations, or other variables of potential practical importance?
To what degree are the quality and generalizability of the polygraph research literature sufficient to support policy decisions regarding use of the polygraph, with particular emphasis on national security screening applications?
Many thousands of works have been written on the polygraph. An extensive bibliography compiled two decades ago (Ansley, Horvath, and Barland, 1983) listed some 3,400 references, and there have certainly been thousands of works on the subject since then. Our interest for this review was in the small proportion of this literature that includes polygraph validation studies, that is, studies that (a) report measurements of one or more of the physiological responses measured by the polygraph and (b) link these physiological responses to the respondent’s truth or deception. Only such studies offer empirical evidence that can be used to assess the criterion validity of the polygraph.
We used several approaches in an effort to obtain as much as possible of the entire corpus of polygraph validation studies. One was a normal literature search using computerized bibliographic databases such as PsycInfo, Social Science Citation Index, Medline, and so forth, using relevant keywords. In addition, we sent requests by regular or electronic mail to a variety of individuals and organizations that we believed might have, or be able to lead us to, research reports useful for this study. These requests went to all U.S. government agencies that do security screening by polygraph, to polygraph websites known to us, and to leading researchers of all persuasions in the polygraph controversy. All contacted were additionally asked to forward our request to others who might also have information potentially useful to us. Finally, we periodically checked our growing bibliography against major published and unpublished bibliographies and reviews of the polygraph literature (e.g., Ansley, Horvath, and Barland, 1983; U.S. Office of Technology Assessment, 1983; Kircher, Horowitz, and Raskin, 1988; Urban, 1999; Ben-Shakhar, personal communication; Defense Information Systems Agency, 2001; U.S. Department of Defense Polygraph Institute, personal communication; Ben-Shakhar and Elaad, 2002). We sought out validation studies regardless of whether or not they had undergone peer review. Through this procedure, we attempted to be as inclusive as possible in collecting material to review, in order to limit publication bias and make our own judgments of research quality.