The Polygraph and the Detection of Deception

Abstract

Over the last decade, Europe has seen a marked increase in the use of the polygraph for the detection of deception. Belgium and Finland nowadays regularly use polygraph tests in criminal investigations, and the United Kingdom and the Netherlands have adopted its use in the treatment and monitoring of sex offenders. Still, the use of the polygraph for the detection of deception has been debated in the scientific literature for ages. In this article, we highlight the promises and perils of the use of the polygraph for the detection of deception.

KEYWORDS:

• polygraph
• lie detector
• deception
• sex offender treatment
• sex offender monitoring

Notes

¹ These percentages do not necessarily add up to 100% because of an inconclusive category. This inconclusive outcome occurs when the magnitude of the reactions to the relevant and the control questions are similar.

² The National Research Council did not report accuracy in terms of percentage correct decisions. This is because percentage-correct decisions rely on an arbitrary cutoff point. The choice of where the cutoff is placed depends on the preference to reduce either the false-positive ratio or the false-negative ratio. Rather, the National Research Council expressed accuracy in terms of the area under the Receiver Operating characteristic Curve (ROC a).

³ This conclusion was highly similar to a U. S. government report that was published 20 years earlier (Office of Technology Assessment, 1983). This report concluded that “…the polygraph detects deception at a rate better than chance, but with error rates that could be considered significant.”

⁴ The British and European Polygraph Association, for example claims that ‘research has shown that the accuracy of computerized polygraph testing is 98 %. See http://europeanpolygraph.org/faqs.htm

⁵ There are two ways to ensure that the different alternatives are equally plausible. First, as with an Oslo confrontation, all alternatives can be presented to a panel of naïve participants with the question to guess which alternative is correct (Doob & Kirschenbaum, 1973). Second, the alternatives can be presented to the suspect before the actual test in a previewing session (Verschuere & Crombez, 2008).