Training Lie Detectors to Use Nonverbal Cues Instead of Global Heuristics


  • The helpful comments by Jeannette Schmid are gratefully acknowledged. Correspondence regarding this article should be sent to Klaus Fiedler, Institut, Universitaet Heidelberg, Hauptstrasse 47–51, 6900 Heidelberg, FRG.


Everyday lie detectors lack the necessary knowledge to use nonverbal cues that discriminate lies from truthful communications. Instead, they rely on general heuristics like infreqtuency of reported events or falsifiability. Lie detectors judged the veracity of 40 reports on minor delinquency that were either truthful or not and referred either to falsifiable manifest actions or to nonfalsifiable subjective feelings. In the uninformed condition, detectors were free to use their intuitive strategies. In the informed condition, they were given detailed instructions about valid nonverbal cues. In the informed feedback condition, they received additional outcome feedback. Performance was generally above chance but further improved through cue information and feedback. Falsifiability caused a bias toward reduced veracity judgments. A lens model analysis supports the interpretation that naive lie detectors follow content-related heuristics but can flexibly change their strategy as they learn about authentic nonverbal cues.