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.
I got this from Yes! 50 Scientifically Proven Ways to Be Persuasive alex.moskalyuk