I was listening to NPR one morning, as I do (I know! So liberal!), and another one of a myriad news reports on the anti-vaccination movement came on. Tired of the ranting, I was going to turn it off when, to my surprise, the woman being interviewed reported that she had actually changed her mind and was willing to talk about it on national radio. That same day, a friend of mine put a link on Facebook to the story of another woman who also changed her mind.

In my experience, people don’t change their minds. On countless sticky issues worldwide, people have generally made up their minds and no amount of evidence will sway them. Climate change, mammography, the Israeli-Palestinian conflict, life after death, breastfeeding, trickle-down economics, Obamacare, all of these issues and many others divide people into impregnable fortresses of common belief and pit followers against one another. As far as I can tell, everyone, even us NPR types, harbor deep and non-negotiable beliefs that don’t yield to fact.

One of the main reasons these firmly held beliefs are so hard to change is also one of humanity’s strongest motivators: fear. Ronald Rogers, the late professor of psychology out of the University of Alabama, who did a lot of work on fear and motivation, proposed that using fear to create motivation involves 3 crucial components:

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  1. The magnitude of noxiousness of the feared event
  2. The probability of the event’s occurrence
  3. The efficacy of a protective response

Some of the things we fear are perfectly reasonable. Unfamiliar dogs, dark alleys in large urban centers, a car accident while driving in the snow, these kinds of fears generate a healthy avoidant response. Having a possibly rabid dog bite is high on the noxiousness index; there are a statistically significant number of dogs in the world who would bite strangers, and staying away from them is a very effective protective response. 

It is irrational fear that causes the problem. A common example is arachnophobia. Some spiders are dangerous. There is a real, if extremely rare, link between danger and spiders. Avoiding all spiders effectively eliminates the risk of getting bit by a poisonous spider. The irrationality in the case of arachnophobia lies in the statistics. Getting bit by a poisonous spider is, in many parts of the world, extremely unlikely.

Fear of vaccinations is a different beast. The fears that cause people to reject vaccination include autism, the long-term effects of chemicals and preservatives, and overwhelming the immune system. In a broader sense, the fears extend to doctors, the medical system, and modern medicine.

Autism is a terrible condition, one that no parent would wish upon a child. There is some possibility that chemicals and preservatives that we are exposed to might someday turn out to be harmful. Avoiding vaccination would be very effective in reducing these fears, if in fact vaccination caused autism and harmful chemical reactions. The reason these fears are irrational is because the threat is not just very unlikely but in fact non-existent. It is to the credit of the woman on NPR that she was able to overcome her own fear and open up her mind to a different reality. That is very hard to do.

The most concerning aspect of the anti-vaccination movement is that it represents a broader fear that has consequences as far reaching as a measles epidemic: fear of modern medicine. The question we should be asking is not “How do we convince people to vaccinate their children?” but “How does medicine re-gain people’s trust?” People trust parenting blogs and websites more than doctors. People trust their peer group more than doctors. People trust Fox News or Jon Stewart more than they trust doctors.

Why? Well, medicine has had some spectacular fails when it comes to trust. Doctors who take money from drug companies or who create “pill mills,” while not common, are well publicized. Hospitals whose bottom line is more important than the patients are now the norm. Research articles are written and peer reviewed by doctors and researchers with ties to the products they are studying, not often, but more often than they should. Doctors order a lot of MRIs when they own the machine, not often, but more often than they should. Procedures are done on a bunch of people who are then told maybe they didn’t need them, as medical knowledge changes. 

People extrapolate these rare but very noxious events to the doctor in front of them, something psychologists call the Availability Heuristic. They figure that since that doctor in Florida couldn’t be trusted to write narcotic prescriptions appropriately, no doctor should be trusted. Because their surgeon gets paid to operate, it seems to them that maybe that surgery they’ve been told they needed is paying for somebody’s boat. They decide that since some article on vaccines and autism, written by a doctor, is purportedly nonsense, they won’t trust that the article really is nonsense, because they don’t trust the people telling them it is nonsense. And just for good measure, they won’t trust any research at all, since you never know. People fear they will be told the wrong thing. Irrational, but not entirely unreasonable.


  1. Rogers RW. A protection motivation theory of fear appeals and attitude change. J Psychology: Interdisciplinary and Applied. 1975;92(1):93-114.