The Rules of Contagion: Why Things Spread - and Why They Stop

by Adam Kucharski

In 2008, political scientists Brendan Nyhan and Jason Reifler proposed that persuasion can suffer from a ‘backfire effect’. They’d presented people with information that conflicted with their political ideology, such as the lack of weapons of mass destruction in Iraq before the 2003 war, or the decline in revenues following President Bush’s tax cuts. But it didn’t seem to convince many of them. Worse, some people appeared to become more confident in their existing beliefs after seeing the new information.[55] Similar effects had come up in other psychological studies over the years. Experiments had tried to persuade people of one thing, only for them to end up believing something else.[56] If the backfire effect is common, it doesn’t bode well for canvassers hoping to convince people to change their minds about issues like same-sex marriage. The Los Angeles LGBT Center thought they had a method that worked, but it needed to be evaluated properly. In early 2013, Dave Fleischer had lunch with Donald Green, a political scientist at Columbia University. Green introduced Fleischer to Michael LaCour, a graduate student at UCLA, who agreed to run a scientific study testing the effectiveness of deep canvassing. The aim was to carry out a randomised controlled trial. After recruiting voters to participate in a series of surveys, LaCour would randomly split the group. Some would get visits from a canvasser; others, acting as a control group, would have conversations about recycling.