Detecting deception by manipulating cognitive load

The majority of lie detection protocols are based on the assumption that, because of their fear of being caught, liars will be more aroused when answering key relevant questions than when answering comparison questions, but this premise is theoretically weak.

Abstract

Concern with crime and terrorism makes it increasingly important to be able to detect lying. Most lie detection tools used to date are arousal-based protocols. The majority of these protocols are based on the assumption that, because of their fear of being caught, liars will be more aroused when answering key relevant questions ('Did you steal the money?') than when answering comparison questions. According to the US National Research Council's well-documented report [ 1 National Research Council (2003) The Polygraph and Lie Detection. Committee to review the scientific evidence on the polygraph (2003), The National Academic Press, Washington, DC Google Scholar ], however, this premise is theoretically weak. Liars do not necessarily reveal more signs of arousal when answering key questions. Conversely, truth tellers might be anxious and hence show signs of arousal when answering key questions.