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The Psychology Behind Why Some Kids Go Unvaccinated


As this country is grappling with the growing outbreak of measles, we have decided to take a look at the psychology of why some parents choose to believe that vaccines are dangerous and what officials might do to persuade them to get their kids immunized. NPR's social science correspondent Shankar Vedantam joins us to talk about this. Hey, Shankar.


GREENE: You know, I want to start by bringing up a story that you did on this program last year. I remember it well. You said that telling parents who are afraid of vaccinating their children about the safety of vaccines might actually go in the other direction. It might be ineffective. They might be less likely to get their kids immunized.

VEDANTAM: That's right, David. This was a study by Brendan Nyhan at Dartmouth, and he and his colleagues found that messages that tout the health benefits and the safety of vaccines are most effective when it comes to persuading people who already believe that vaccines are safe and effective. When it comes to parents who are worried about the safety of vaccines, the researchers found the messages were not only ineffective, but potentially counterproductive because worried parents became less likely to want to vaccinate their children after hearing these messages.

GREENE: Why would that be? Why would people who hear a message that vaccines are safe, you know, be even less likely to get these vaccinations?

VEDANTAM: You know, David, there is a small warehouse backed with research studies that find that our beliefs on all manner of issues are shaped by our pre-existing views. You know, that doesn't we're completely deaf to the evidence, it just means that we filter how we interpret the evidence through our pre-existing beliefs and our loyalties to various groups and tribes. And we see this in all manner of settings, not just in public health settings. The people who believe President Obama was born in Kenya, for example, were overwhelmingly likely to be people who didn't like President Barack Obama. If you looked at the recent football scandal over deflated footballs, people in New England were far more likely than people anywhere else in the country to believe that quarterback Tom Brady and coach Bill Belichick didn't know what was going on. So vaccines and the concerns about vaccines are an example of this much larger phenomenon, which is once you believe in something, it's very hard to debunk that belief. And when someone comes along and tries to debunk that belief, they get seen as being part of the conspiracy theory.

GREENE: They sort of settle more tightly into the views that they have. They don't trust you. They think you're part of the problem. They close their ears to what you're saying.

VEDANTAM: Exactly. Now, it's very easy for us to see this kind of motivated reasoning at work when it comes to the views of other people, especially people from other groups. In northern Nigeria, for example, some Muslim groups have long been worried that the polio vaccine has been laced with the AIDS virus as part of a plot to kill off Muslims. Now, for people on the outside, this might seem absurd. But, of course, when you look at it from the inside, it looks completely different.

GREENE: If not getting vaccinated is a real problem here in this measles outbreak, and we're talking about people who are getting very sick, I mean, this is sort of depressing that the idea of promoting safety doesn't work. Are their ideas about what could work here?

VEDANTAM: Well, one interesting idea is to think of vaccines as being a collective action dilemma - what social scientists would call a collective action dilemma. You know, we all benefit, David, when everyone is vaccinated. But each of us actually has a selfish incentive to free-ride off of everyone else, and here's what I mean. If I don't vaccinate my kid, but everyone else does, I don't have to bother with making my kid upset and dealing with the very small risk that vaccines can pose. And if everyone else has vaccinated their kids, my kid is actually likely to be safe because there is this moat that's built around him or her.

GREENE: The problem, of course, is if everyone is thinking that way, there's no moat.

VEDANTAM: Exactly right. And that's why these dilemmas are sometimes called tragedies of the commons. They pit individual self-interest against what's in the common good. Now, there have been a lot of people who've thought about ways to solve collective action dilemmas. Some countries simply force everyone to vaccinate their kids. So if you coerce everyone to vaccinate their kids, that gets around the dilemma. Another solution is to apply public and social pressure. So this is sort of a social free market solution if you will. If you know that I haven't vaccinated my kid, you might be less likely to invite him over for a play date with your kids, and that puts pressure on me to get my kid vaccinated.

GREENE: Pressure that sort of forces people, in a way, to put social interest ahead of their own selfish interests.

VEDANTAM: Exactly. Now, a lot of people who study human behavior and have thought deeply about how you get people to change their beliefs think that coercion and shaming people is not the way to go. The way to go is actually to build relationships and build trust. You know, David, when my child has a nightmare, I don't come to her in the middle of the night and say, look, you're a moron for believing there's a monster under your bed. I acknowledge that the fear might be real, even if there's no monster under the bed. And we - I sort of help her deal with the fear.

So what we know for sure is that the parents who are not vaccinating their kids are afraid. So the place to start might be to acknowledge that fear is real and to deal with it. So when doctors and public health officials start from there - when they start from the heart and not from the head, they might actually make more headway in getting parents to vaccinate their children.

GREENE: Because there has been this sense of parents who don't believe these vaccinations are safe - they've been ridiculed and people have sort of dismissed them.

VEDANTAM: Exactly, and I'm not quite sure that being told that you're a moron is actually very helpful when you're actually confronting something you believe is a life-and-death issue for your own child.

GREENE: Shankar, thanks a lot.

VEDANTAM: Thank you, David.

GREENE: That's NPR's social science correspondent Shankar Vedantam. Transcript provided by NPR, Copyright NPR.

Shankar Vedantam is the host and creator of Hidden Brain. The Hidden Brain podcast receives more than three million downloads per week. The Hidden Brain radio show is distributed by NPR and featured on nearly 400 public radio stations around the United States.