Ads quoting negative behavior en masse reinforces negative behavior. Petrified Forest National Park A/B tested two versions of a sign imploring people not to steal pieces of petrified forest from the park. One mentioned large amounts of petrified forest taken away on an annual basis, the other one simply asked the visitors not to remove petrified wood. The first one actually tripled the theft ratio as it showed stealing petrified wood as something commonplace. Same effect was observed after airing an ad that implored women to vote, but mentioned that 22 million single women did not vote last year. That kind of information actually portrays not voting as more socially acceptable.

Nate

Towards the end of his 27 years in jail, Nelson Mandela began to yearn for a hotplate. He was being well fed by this point, not least because he was the world’s most famous political prisoner. But his jailers gave him too much food for lunch and not enough for supper. He had taken to saving some of his mid-day meal until the evening, by which time it was cold, and he wanted something to heat it up.

The problem was that the officer in charge of Pollsmoor prison’s maximum-security “C” wing was prickly, insecure, uncomfortable talking in English and virtually allergic to black political prisoners. To get around him, Mr Mandela started reading about rugby, a sport he had never liked but which his jailer, like most Afrikaner men, adored. Then, when they met in a corridor, Mr Mandela immediately launched into a detailed discussion, in Afrikaans, about prop forwards, scrum halves and recent games. His jailer was so charmed that before he knew it he was barking at an underling to “go and get Mandela a hotplate!”