By Dr. Ken Broda-Bahm:
The prospects for persuasion in some cases can seem quite dismal. Those who are most committed to a false belief, and therefore most in need of persuasion, are also those who are most likely to turn away information that questions those existing views. Indeed, the act of hearing and responding to opposing views can make your target all the more committed to the belief you're trying to change. A recent Mother Jones Article reports on one such situation, focusing on the views of parents who oppose childhood vaccination, believing that this preventative step carries great health risks including autism. The article reports on research showing the apparent impossibility of changing the minds of the anti-vaccine crowd. The researchers from Dartmouth College and Exeter in the U.K. (Nyhan et al., 2014) set out to test four different messages based on information shared by the Centers for Disease Control. Not one of the messages had a significant effect in getting the anti-vaccine group to accept the argument that vaccinating carries much less risk than not vaccinating. Worse, several of the corrective messages actually backfired and made viewers even more opposed to vaccination.
The goal was to find out what persuasive approach worked best. One message focused on showing the science refuting any connection with autism. A second message focused on the higher risks and consequences of diseases in unvaccinated children. A third message consisted of a story of an unvaccinated 10-month-old child who experienced a life-threatening fever as a result of that decision. A fourth shared imagery of diseases made more likely by avoidance of vaccines. All four failed, in some cases dramatically. In response to the first message, Mother Jones reported, "the likelihood of saying they would give their kids the MMR vaccine decreased to 45 percent (versus 70 percent in the control group) after they received factual, scientific information debunking the vaccine's autism link." So, it is not exactly a ringing endorsement of the potential for human persuasion. Because these results are already well reported in the Mother Jones article, as well as a second related article, I am going to instead take a detective's view of why that backfire effect might occur. The two likely suspects point to a couple of important principles that apply broadly to persuasion.