npr:

It’s a common experience for family members or groups of friends: One person’s mood can bring the whole group’s energy down— or up. But why are we so easily influenced?

In 1962, the reality television show Candid Camera offered a remarkable glimpse into a psychological phenomenon that helps explain how emotions spread. They did it through a now famous comedy stunt called “Face the Rear.”

It goes like this: We see an unsuspecting man walk into an elevator that has been secretly rigged with cameras. Two more people walk in after him. But weirdly, they turn to face towards the back wall of the elevator. The man looks confused, but continues facing front, despite the two weirdos next to him. But when a third person comes in and faces the back wall, the poor guy can’t take it anymore and turns to the back wall too.

Now the dance is on. The three newcomers now turn forward and the target of the prank whips around to join them. Candid Camera observes this phenomenon again and again. An unsuspecting victim would walk into that elevator and end up imitating whatever the people around him were doing.

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