In the widespread debate about the recent niqab in court controversy,* one of the things that strikes me is how little anyone participating in the debate actually knows about the influence of demeanour on the accurate assessment of evidence. I add myself to that group. I know little about it either. I do know that there is a significant body of work in such fields which can and should inform judgments about whether a woman wearing a niqab in court to give evidence would make the jury’s job harder. So I have had a quick look and came across this study. It is a meta-analysis of jury research by Michael Saks (6 S. Cal. Interdisc. L.J. 1 (1997-1998) What Do Jury Experiments Tell Us about How Juries (Should) Make Decisions). A key passage says this:
Trial courts put enormous stock in assessment of the credibility of witnesses as a vital path to correct factfinding. Moreover, they have remarkable faith in the ability of factfinders to evaluate credibility by using demeanor evidence. Appellate courts routinely defer to trial court factfinding based in part on the notion that the factfinders at
The question, then, is how good are we humans at using demeanor evidence to detect truth-telling or lying? A considerable amount of research has been conducted in recent decades, on nonverbal behavior and the detection of deception. The findings indicate that demeanor cues often reduce
accuracy in detecting deception, by distracting people into looking at cues they think are associated with lying and overlooking cues that actually are. …
…Apparently, facial cues provide little help and sometimes do more harm than good. By contrast, subjects given transcripts alone are better at detecting deception than any of the conditions we have considered thus far…. Speech sounds alone, with no visual cues at all, raise performance further…. So much for the notion that nonverbal channels of communication carry more information than verbal channels for human deception detectors to rely upon. Adding body cues to speech raises performance to its height …. Adding facial cues to speech-with or without body cues drags performance below what it was with speech alone. In sum, jurors would be better advised to disregard witnesses’ faces if they want to maximize their ability to detect deception, or just wear a blindfold and listen closely. Appellate judges listening to an audiotape would do at least as well as jurors (or, presumably, trial judges) who had access to both face and body cues ….
I am not saying this study is the last word, or even the right word, on the subject (I’d have to immerse myself in the literature for a while to be confident and I only have fifteen minutes on the computer before my daughter needs to do her homework to do that), but this sort of research is little known to lawyers and judges, who insist that demeanour is very important to judging witness veracity. There is at least a plausible, evidence-based case, that this is not so – and the reverse may even be true. The belief that we can assess honesty through demeanour is part of legal folklore but it may also be a myth.