Lying is one of the most elusive qualities humans have. For that reason, two researchers at the University of Chicago’s business school set out learn the best way to increase accuracy when detecting a lie. The study, published in Proceedings of the National Academy of Sciences, is the first to discover how powerful lie detection is when done collaboratively in groups.

“We find a consistent group advantage for detecting small 'white' lies as well as intentional, high-stakes lies told for personal gain,” said the study’s lead author Nicholas Epley, a business professor, in a press release. “This group advantage seems to come through the process of group discussion rather than statistical aggregation of individual opinions.”

For the study, researchers set up two video viewings. Each three-person group watched videos of different people saying different statements. They were then asked to figure out if the statement was a truth or a lie after discussing it among the group. Afterward, the groups were split up so each person could undergo the experiment again, but with different videos.

“Interventions to improve lie detection typically focus on improving individual judgment, which is costly and generally ineffective,” Epley said. '”Our findings suggest a cheap and simple synergistic approach of enabling group discussion before rendering a judgment.”

When the study’s participants were able to work together to figure out whether the statement in the video was a lie, they were right more than 60 percent of the time. Left alone to decide, they were only right a little more than 50 percent of the time. Even when the lies told more high-stakes, groups were more accurate.

“Existing research demonstrates that increasing incentives for accuracy among lie detectors does not increase accuracy, but that increasing incentives for effective deception among lie tellers make lies easier to detect," Epley explained. "Therefore, we did not manipulate lie detectors' incentives to detect truth versus lies accurately, but instead asked participants to detect truths versus lies in low-stakes and high-stakes contexts for the lie tellers.”

People have been trying to determine how to spot a lie for years. A meta-analysis performed in 2011 examined dozens of lie detector studies. The researchers looked at different lying cues like fidgeting, postural shifts, head movements, gaze aversion, and speech rate, yet none of the strategies were able to achieve the same accuracy as a group. The groups were not just maximizing the small amounts of accuracy each individual contributed, but also creating a unique, cohesive type of accuracy altogether.

Source: Epley N and Klein N. Group discussion improves lie detection. Proceedings of the National Academy of Sciences. 2015.