How good-cop-bad-cop works: Disorient people by relieving the fear abruptly.

http://io9.com/when-scientists-simulate-good-cop-bad-cop-things-get-1677692207

Polish scientists ran some experiments on an unsuspecting public to find out the mechanism behind good-cop-bad-cop.

In one experiment they waited until somebody jaywalked across the street, then blew a whistle as if a policeman called them to stop.
The victim... I mean, the subject would then turn around being afraid, only to be suddenly relieved by seeing it wasn't a policeman after all. Immediately after that, phase 2 was initiated: The subject was approached by a person with a clipboard, asking for a donation. The people who had been frightened the most, needed the least persuasion to hand over their money.

A second experiment found out that good-cop-bad-cop doesn't work when critical thinking skills are kickstarted with a simple math-question.

And for the last one:
"For the last experiment, the researchers mounted a full production. They had groups come in and do simple tasks, like spotting a target or doing basic addition. One third of the time, that would be it. Another third of the time the scientists announced that people who fell behind would receive electric shocks. And for the final third of the time, they announced that people would receive electric shocks, then had a researcher come in, announce that this was the wrong group, and they would not be getting shocks.

This time, fear-and-relief seemed to be in full swing. The control group, who did their problems without any threat of shocks, got through the task fastest. The soon-to-be-shocked group was a little slower. Lagging well behind both, however, was the discombobulated fear-then-relief group, unable to mentally get it together."



"I'm so sorry. There has been a mix-up. We won't electroshock you after all."