The science of persuasion

I've heard and read various items about persuasion recently which all seem to point back to a book by Robert Cialdini about the science of persuasion. Apparently we look for "social proof" before we do something. It's a kind of runaway effect. Those hotel bathroom signs asking you to re-use towels work quite well, but signs telling you (truthfully) that most people re-use their towels work even better. In the Petrified Forest in Arizona, signs saying how awful it was because so many tons of fossilized wood was being stolen brought about a threefold increase in theft, whereas signs saying how awful it is if only one person steals wood produce a 50% reduction in theft. We follow the crowd, for good or ill.

This makes me think that the media have a lot to answer for in the way they report good and bad aspects of society. If they give the impression that most kids carry knives, then that will be self-fulfilling, whereas if they stress the rarity of knife crime it will surely make it feel less cool to carry a knife. On the other side, I've often been annoyed by the media's tendency in the past to portray cycling as a quirky pastime (cue bicycle bells at start and end of a radio clip about cycling), whereas more recently it has been refreshing to see statistics highlighting how fast cycle use is growing in London for example. This could be another self-fulfilling prophecy - I hope so!