T. Brennen & S. Magnussen
Front. Psychol., 14 December 2020
Introduction
Research on the detection of lies and deceit has a prominent place in the field of psychology and law with a substantial research literature published in this field of inquiry during the last five to six decades (Vrij, 2000, 2008; Vrij et al., 2019). There are good reasons for this interest in lie detection. We are all everyday liars, some of us more prolific than others, we lie in personal and professional relationships (Serota et al., 2010; Halevy et al., 2014; Serota and Levine, 2015; Verigin et al., 2019), and lying in public by politicians and other public figures has a long and continuing history (Peters, 2015). However, despite the personal problems that serious everyday lies may cause and the human tragedies political lies may cause, it is lying in court that appears to have been the principal initial motivation for the scientific interest in lie detection.
Lying in court is a threat to fair trials and the rule of law. Lying witnesses may lead to the exoneration of guilty persons or to the conviction of innocent ones. In the US it is well-documented that innocent people have been convicted because witnesses were lying in court (Garrett, 2010, 2011; www.innocenceproject.com). In evaluating the reliability and the truthfulness of a testimony, the court considers other evidence presented to the court, the known facts about the case and the testimonies by other witnesses. Inconsistency with the physical evidence or the testimonies of other witnesses might indicate that the witness is untruthful, or it may simply reflect the fact that the witness has observed, interpreted, and later remembered the critical events incorrectly—normal human errors all too well known in the eyewitness literature (Loftus, 2005; Wells and Loftus, 2013; Howe and Knott, 2015).
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Is the rational course simply to drop this line of research? We believe it is. The creative studies carried out during the last few decades have been important in showing that psychological folklore, the ideas we share about behavioral signals of lies and deceit are not correct. This debunking function of science is extremely important. But we have now sufficient evidence that there are no specific non-verbal behavioral signals that accompany lying or deceitful behavior. We can safely recommend that courts disregard such behavioral signals when appraising the credibility of victims, witnesses, and suspected offenders. For psychology and law researchers it may be time to move on.
