The detection of deception during trials: Ignoring the nonverbal communication of witnesses is not the solution—A response to Vrij and Turgeon (2018)
| Author | Pierrich Plusquellec,Vincent Denault,Norah E. Dunbar |
| DOI | 10.1177/1365712719851133 |
| Published date | 01 January 2020 |
| Date | 01 January 2020 |
| Subject Matter | Articles |
The International Journal of
Evidence & Proof
The detection of deception during
2020, Vol. 24(1) 3–11
ª The Author(s) 2019
trials: Ignoring the nonverbal
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communication of witnesses is
DOI: 10.1177/1365712719851133
journals.sagepub.com/home/epj
not the solution—A response to
Vrij and Turgeon (2018)
Vincent Denault
Universite´ de Montre´al, Quebec, Canada
Norah E Dunbar
University of California, Santa Barbara, USA
Pierrich Plusquellec
Universite´ de Montre´al, Quebec, Canada
Abstract
In their paper ‘Evaluating credibility of witnesses—Are we instructing jurors on invalid
factors?’, Vrij and Turgeon (2018) argue that jurors should be advised not to consider
demeanour when trying to evaluate if witnesses are honest or dishonest because of ‘over-
whelming scientific evidence’. However, in this response, we contend that substantial empirical
scientific studies on nonverbal communication alongside the limitations of deception detection
research, as cited by Vrij and Turgeon (2018), undermine their overall argument. While jurors
should be warned about erroneous beliefs and dubious concepts on human communication,
jurors should also be advised to consider demeanour as a way of enriching their overall
understanding of witnesses and their verbal testimony.
Keywords
Deception detection, jury instruction, nonverbal communication, trials, witnesses
When witnesses testify during trials—even if they are under oath—some will not tell the truth, the whole
truth and nothing but the truth (Fawcett, 2014). In adversarial legal systems, such as those in Canada and
the United States, if jurors in jury trials (or judges in bench trials) fail to correctly identify honest and
Corresponding author:
Vincent Denault, Universite´ de Montreal, 90, avenue Vincent-d’Indy, Outremont (Que´bec), Montreal, QC Quebec H2V 2S9,
Canada.
E-mail: vincent.denault@umontreal.ca
4
The International Journal of Evidence & Proof 24(1)
dishonest witnesses or if they think that honest witnesses are dishonest and that dishonest witnesses are
honest, the consequences can be substantial. In criminal trials, the last step of the judicial process, the
liberty of defendants or even their life (in countries where there is still the death penalty) can depend on
the deception detection ability of jurors. However, the consequences of inappropriate assessments of
testimonies can be detrimental beyond criminal trials. For example, in commercial trials, companies can
lose their reputation. In family trials, parents can lose custody of their children. In civil trials, people can
lose their life savings. Despite such dire consequences, very little attention has been paid to the detection
of deception during trials (Denault and Dunbar, 2019). In their paper ‘Evaluating credibility of wit-
nesses—Are we instructing jurors on invalid factors?’, Vrij and Turgeon (2018) address this very
important issue.
The authors argue that jurors should be advised not to consider demeanour when trying to evaluate if
witnesses are honest or dishonest because of ‘overwhelming scientific evidence’ (Vrij and Turgeon,
2018: 1). Vrij and Turgeon (2018) call attention to meta-analyses showing that nonverbal cues to deceit
are generally faint and unreliable (DePaulo et al., 2003; Sporer and Schwandt, 2007), that people using
nonverbal cues have poor deception detection accuracy (Bond and DePaulo, 2006) and that training to
improve accuracy of deception detection using nonverbal cues generally offers mediocre results (Frank
and Feeley, 2003; Hauch et al., 2014). The authors then reflect on two possible reasons why people
overly rely on nonverbal cues to deceit. Finally, Vrij and Turgeon (2018) detail techniques to improve
accuracy of deception detection using verbal cues to deceit. They conclude that ‘current well-accepted
scientific studies support that human evaluation of a person’s credibility based upon nonverbal beha-
viours such as manner and appearance is unreliable in determining believability’ (Vrij and Turgeon,
2018: 11).
However, in this response, we contend that substantial empirical scientific studies on nonverbal
communication alongside the limitations of deception detection research, as cited by Vrij and Turgeon
(2018), undermine their overall argument. While jurors should be warned about erroneous beliefs and
dubious concepts on human communication, jurors should also be advised to consider demeanour as a
way of enriching their overall understanding of witnesses and their verbal testimony. We end this
response with an amended version of Vrij and Turgeon’s (2018) proposed jury instruction.
Erroneous beliefs and dubious concepts on nonverbal communication
Nonverbal communication, that is, ‘communication effected by means other than words, assuming
words are the verbal element’ (Knapp et al., 2014: 8), has been extensively studied for the past
50 years. Thousands of peer-reviewed papers from an international scientific community have been
published and the field of deception detection has grown substantially (Plusquellec and Denault, 2018;
Vrij et al., 2019). However, despite the large body of knowledge regarding the subject, the general public
and justice professionals still tend to hold erroneous beliefs, including those related to nonverbal cues to
deceit (Bogaard et al., 2016; Denault, 2015; Stro¨mwall and Granhag, 2003; The Global Deception
Research Team, 2006). Moreover, pseudoscientific programmes, methods and approaches to ‘catch
liars’ are marketed for usage in courtrooms (Denault et al., 2019; Denault and Jupe, 2017; Jupe and
Denault, 2018). When considering the above, even if both the Supreme Court of Canada and the United
States Supreme Court mentioned demeanour as a factor to assess the credibility of witnesses (Coy v
Iowa, 1988; Mattox v United States, 1895; R v D.A.I., 2012), ignoring facial expressions and gestures in
courtrooms might seem appropriate. However, rather than solving a problem, such advice may create
additional issues, and the judicial fact-finding process could be undermined.
While the general public and justice professionals hold erroneous beliefs on nonverbal cues to deceit,
they also hold erroneous beliefs on vocal and verbal messages (Bogaard et al., 2016; The Global
Deception Research Team, 2006). The consistency of testimonies and the spontaneity of witnesses, for
example, are associated with truthfulness. However, they are not reliable...
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