Throwing science at anti-vaxxers just makes them more hardline

High trust, low expertise
Some of my own research has looked at who the public trusted to inform them about the risks from pollution. Our finding was that how expert a particular group of people was perceived to be — government, scientists, or journalists, say — was a poor predictor of how much they were trusted on the issue. Instead, what was critical was how much they were perceived to have the public’s interests at heart. Groups of people who were perceived to want to act in line with our respondents’ best interests — such as friends and family — were highly trusted, even if their expertise on the issue of pollution was judged as poor.

By implication, we might expect anti-vaxxers to have friends who are also anti-vaxxers (and so reinforce their mistaken beliefs) and to correspondingly have a low belief that pro-vaccine messengers such as scientists, government agencies, and journalists have their best interests at heart. The corollary is that no amount of information from these sources — and no matter how persuasive to you and me — will convert anti-vaxxers who have different beliefs about how trustworthy the medical establishment is.

Interestingly, research done by Brendan Nyhan has shown many anti-vaxxers are willing to drop mistaken beliefs about vaccines, but as they do so they also harden in their intentions not to get their kids vaccinated. This shows that the scientific beliefs of people who oppose vaccinations are only part of the issue — facts alone, even if believed, aren’t enough to change people’s views.

Reinforced memories
We know from research on persuasion that mistaken beliefs aren’t easily debunked. Not only is the biased assimilation effect at work here but also the fragility of memory — attempts at debunking myths can serve to reinforce the memory of the myth while the debunking gets forgotten.

The vaccination issue provides a sobering example of this. A single discredited study from 1998 claimed a link between autism and the MMR jab, fuelling the recent distrust of vaccines. No matter how many times we repeat that “the MMR vaccine doesn’t cause autism,” the link between the two is reinforced in people’s perceptions. To avoid reinforcing a myth, you need to provide a plausible alternative — the obvious one here is to replace the negative message “MMR vaccine doesn’t cause autism,” with a positive one. Perhaps “the MMR vaccine protects your child from dangerous diseases.”

Rational selfishness
There are other psychological factors at play in the decisions taken by individual parents not to vaccinate their children. One is the rational selfishness of avoiding risk, or even the discomfort of a momentary jab, by gambling that the herd immunity of everyone else will be enough to protect your child.

Another is our tendency to underplay rare events in our calculation about risks — ironically the very success of vaccination programs makes the diseases they protect us against rare, meaning that most of us don’t have direct experience of the negative consequences of not vaccinating. Finally, we know that people feel differently about errors of action compared to errors of inaction, even if the consequences are the same.

Many who seek to persuade anti-vaxxers view the issue as a simple one of scientific education. Anti-vaxxers have mistaken the basic facts, the argument goes, so they need to be corrected. This is likely to be ineffective. Anti-vaxxers may be wrong, but don’t call them irrational.

Rather than lacking scientific facts, they lack a trust in the establishments which produce and disseminate science. If you meet an anti-vaxxer, you might have more luck persuading them by trying to explain how you think science works and why you’ve put your trust in what you’ve been told, rather than dismissing their beliefs as irrational.

Tom Stafford isLecturer in Psychology and Cognitive Science at University of Sheffield. This story is published courtesy of The Conversation (under Creative Commons-Attribution/No derivatives.