How good are you at knowing when people are telling you the truth and when they're lying? Generally, I'd wager that the average person probably thinks they're better than average. And those who are self-styled experts or who have undergone training in lie detection likely believe that they have a decided advantage in spotting the liars. There's just one problem with that: A long line of experimental research shows that when trying to detect falsehoods, even trained experts typically fare little better than chance. When tested in blind experiments, 'human lie detectors' are about as good as coin flips. A recent study (Klein & Epley, 2015) however, takes a different approach. Instead of simply testing individuals with and without training on their ability to detect deception, they looked at groups, specifically in regard to the question of whether deliberation improves their ability to tell truth from fiction. 

The result? Groups indeed did significantly better than individuals at detecting deception. And it isn't just the benefits of aggregating individual opinions, the so-called "wisdom of the crowd," and it isn't due to the group's ability to spot and rely on the most capable lie-spotter in their group. Instead, the group's advantage in spotting lies has to do with the process of group discussion and the benefits of deliberation. I've written previously on the importance of understanding and adapting to the jury's process during deliberations. This research, however, adds to the pool of evidence showing the benefits of group discussion and, more specifically, the benefits of the jury model. This post takes a quick look at the research as well as a few implications that stem from it. 

The Research: Groups Are Better  

Nadav Klein and Nicholas Epley (2015) of the University of Chicago's Booth School of Business set out to see if there was a measurable advantage in relying on groups as lie detectors. They believed that there were three possible reasons why there might be: One, there could be a "wisdom of the crowd" advantage in aggregated opinions; two, there might be a tendency for groups to be more skeptical and less biased toward believing that they're hearing the truth; or three, there could be an advantage to the group's deliberations. 

Comparing individuals to groups in their ability to tell whether people were telling the truth or lying, they tested both small, inconsequential lies as well as higher stakes intentional lies. The conclusion: "Our experiments showed a consistent group advantage for detecting small “white” lies in the laboratory as well as high-stakes lies told intentionally for personal gain."

 Implications

Of course, spotting lies isn't the only role of a jury. In practice, their job is to react to the overall stories presented by both sides and to map those onto the law through the filter of their own understanding and common sense. But some of the reasons why groups are better lie detectors also suggest that groups are better at this general task of judgement. In other words, our forefathers and mothers were correct to embrace a jury system for resolving public and private disputes. 

A Group is More Than the Sum of Its Parts

In addition to testing the effectiveness of actual groups versus individuals, Klein and Epley also looked at "nominal groups" created by statistically aggregating individual responses. Those aggregations ended up faring no better than individuals at detecting falsehoods. Discussing the advantage of the real groups, they noted, "Groups were not simply maximizing the small amounts of accuracy contained among individual members but were instead creating a unique type of accuracy altogether." 

Discussion Matters

And that unique type of accuracy, as much as the authors can determine, stems from discussion. As Rita Handrich wrote in The Jury Room, "While the researchers featured here today don’t know just how the magic happens, it is clear the magic does happen during group discussion (aka jury deliberation). It is a compass pointing to truth that is unavailable in bench trials, and arguably in arbitrations as well." That advantage should give pause to anyone using online "mock trials" that don't allow deliberations -- you might be gaining a trove of quick data, but you're missing one of the key ingredients.

And, Tell the Truth 

We say it to every witness -- above all, tell the truth. The ethical reasons for that would be strong enough, but there is a strong practical reason as well. Any suggestion of dishonesty -- not just outright lying, but subtle exaggerations, or making a memory more certain than it ought to be -- and your jury has just reduced your credibility in a way that discounts or negates everything you've said. Outside the witness box, advocates should take that to heart as well. Of course, it's your job to put your case in the best light possible. But if your case has weaknesses (and all cases do), then you'll often do better to just honestly admit those weaknesses. Fighting the obvious -- as the jury sees it -- weakens your credibility as well. 

If it bears out in future research, the group advantage in detecting deception that Klein and Epley observed will add one more to the list of the jury's advantages. Like the many-eyed Argus of Greek mythology, not a lot gets past them.