Groups are better lie detectors than individuals.

From Klein and Epley:

Significance

Detecting lies is difficult. Accuracy rates in experiments are only slightly greater than chance, even among trained professionals. Costly programs aimed at training individual lie detectors have mostly been ineffective. Here we test a different strategy: asking individuals to detect lies as a group. We find a consistent group advantage for detecting small “white” lies as well as intentional high-stakes lies. This group advantage does not come through the statistical aggregation of individual opinions (a “wisdom-of-crowds” effect), but instead through the process of group discussion. Groups were not simply maximizing the small amounts of accuracy contained among individual members but were instead creating a unique type of accuracy altogether.

Abstract

Groups of individuals can sometimes make more accurate judgments than the average individual could make alone. We tested whether this group advantage extends to lie detection, an exceptionally challenging judgment with accuracy rates rarely exceeding chance. In four experiments, we find that groups are consistently more accurate than individuals in distinguishing truths from lies, an effect that comes primarily from an increased ability to correctly identify when a person is lying. These experiments demonstrate that the group advantage in lie detection comes through the process of group discussion, and is not a product of aggregating individual opinions (a “wisdom-of-crowds” effect) or of altering response biases (such as reducing the “truth bias”). Interventions to improve lie detection typically focus on improving individual judgment, a costly and generally ineffective endeavor. Our findings suggest a cheap and simple synergistic approach of enabling group discussion before rendering a judgment.