Finally, in the fourth experiment, Klein and Epley tested whether having a group discussion made any difference to people’s ability to detect lies. They split the participants into two sets, with groups within each. The groups in the first set started with a group discussion based on videos of individuals making statements, and made group judgment of whether they had been told a lie or the truth. After that, their individual judgments were recorded. The groups in the second set had their individual judgments recorded first, before the group discussion.

Klein and Epley found that the judgment participants expressed first had an effect on the judgment they made next. When checked against what was actually true, it emerged that having a group discussion first seemed to help individuals increase the chance of coming to the correct conclusion.

Interestingly, neither the wisdom of crowds nor the groups’ advantage against truth bias seemed helped groups do better. Instead, Klein and Epley argue that it is simply the group discussions that elicit new and useful information, which helps improve people’s chances of catching lies.

The upshot: While it makes sense to avoid useless meetings, if you and your colleagues find yourself in the unfortunate position of needing to catch a liar, there seems to be some value in sitting down as a group to talk it over.

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