Unfortunately, there is a major obstacle when it comes to finding a persuasive argument. If we have a strong opinion, Bayesian reasoning implies that we will struggle to distinguish the effects of arguments that support this existing view. Suppose you strongly believe in something. It could be anything from a political stance to an opinion about a film. If someone presents you with evidence that is consistent with your belief – regardless of whether this evidence is compelling or weak – you will go away with a similar opinion afterwards. Now imagine someone makes an argument against your belief. If that argument is weak, you won’t change your view, but if it is watertight, you might well do so. From a Bayesian point of view, we are generally better at judging the effect of arguments that we disagree with.[67]
That’s if we even think about different arguments. A few years ago, social psychologists Matthew Feinberg and Robb Willer asked people to come up with arguments that would persuade someone with an opposing political view. They found that many people used arguments that matched their own moral position, rather than the position of the person they were trying to persuade. Liberals tried to appeal to values like equality and social justice, while conservatives based their argument on things like loyalty and respect for authority. Arguing on familiar ground might have been a common strategy, but it wasn’t an effective one; people were far more persuasive when they tailored their argument to the moral values of their opponent. This suggests that if you want to persuade a conservative, you’re better off focusing on ideas like patriotism and community, whereas a liberal will be more convinced by messages promoting fairness.[68]
Even if you manage to identify an effective argument to support your position, there are things you can do to improve your chances of persuasion. First, the delivery method can matter. There’s evidence that people are much more likely to complete a survey if asked in person rather than by e-mail,[69] for example. Other experiments have come to similar conclusions, finding that people can be more convincing face-to-face than by phone, post or online.[70]
The timing of messages can also make a difference. According to Briony Swire-Thompson, a psychologist at Northeastern University, researchers are increasingly thinking about how ideas wane. ‘It’s this concept that once you change someone’s mind, it doesn’t stick permanently.’ In 2017, she conducted a study asking people whether they believed certain myths, like carrots improving your eyesight or liars moving their eyes in a certain direction.[71] The study found that they could often correct false beliefs, but the effect didn’t necessarily last. ‘If you get a correction, you might reduce your belief initially, but as time goes on you’re going to re-believe in the initial misconception,’ Swire-Thompson said. It seems repetition matters: new beliefs survived longer if people were reminded of the truth several times, rather than just given one correction.[72]
Thinking about the moral position of others. Having face-to-face interactions. Finding ways to encourage long-term change. All of these things can help improve persuasion. And it happens that they are also part of the deep canvassing approach advocated by the Los Angeles LGBT Center. Which brings us back to that dubious LaCour and Green paper. Although the study was retracted in 2015, the story didn’t end there. The following year, David Brookman and Joshua Kalla – those two Berkeley researchers who’d found the problems in the original paper – published a new study.[73] This one focused on transgender rights. And this time they’d definitely collected the data.
Comparing deep canvassing with results from a control group, they’d found that a ten-minute conversation about transgender rights could noticeably reduce prejudice. It didn’t matter whether the canvasser was transgender; the change in voters’ opinion persisted regardless. The change in belief also seemed to be resistant to attacks. After a few weeks, the researchers showed people anti-transgender adverts from recent political campaigns. The ads initially swung opinions back against transgender people, but this reversion effect soon faded.
To ensure the research was completely transparent, Brookman and Kalla published all the data and code behind the analysis. It provided an optimistic epilogue to what had been an awkward few years for the research community. With the right approach, it was possible to change attitudes that many had believed were deeply ingrained. It showed that views don’t necessarily spread in the way we assume they do, nor are people as fixed as we think they might be. When faced with apparent hostility, it seems there can be a lot to gain by trying something new.
4
Something in the air
‘We were in a place with real violence.’ After a decade spent working on disease epidemics in Central and East Africa, Gary Slutkin had returned home to the United States. He’d chosen Chicago to be near his elderly parents and was struck by the extent of violent attacks in the city. ‘It was surrounding, it was inescapable and so I just started to ask people what they were doing about it,’ Slutkin said. ‘And there wasn’t anything that anybody was doing about this that made any sense to me.’[1]
It was 1994 and in the preceding year, there had been over eight hundred homicides in the city, including sixty-two children killed in gang violence. Even two decades later, homicide would still be the main cause of death for young adults in the state of Illinois.[2] Slutkin heard a range of
