The Stranger Is a Secret Weapon

Psychologists gave murder mystery problems to students. Groups with a stranger did much better yet, with a success rate of 75%. But what's really interesting is not just that the groups with the stranger made smarter decisions, but how they felt about it. Here's what seems like an obstacle, this awkward stranger sitting in the group and spoiling everyone's fun. But the obstacle is actually a secret weapon. The stranger dramatically improves the mance of the group, yet the people in the group don't realize it.