A Self-Affirmation Exercise Does Not Improve Intentions to Vaccinate among Parents with Negative Vaccine Attitudes (and May Decrease Intentions to Vaccinate)

Lower-than-ideal vaccination rates in the United States (US) are a growing public health concern and have been implicated in several measles and pertussis outbreaks. Researchers have tested various messaging techniques to decrease negative vaccine attitudes and to increase vaccination rates, but have found it difficult to change parents' negative attitudes. The present study attempted to apply a psychological intervention - a self-affirmation exercise - to vaccine safety messaging for parents.

The rise in parents choosing not to vaccinate their children may be partially due to parental fears that vaccines cause serious side effects, including autism. Researchers have tested the effect of various messaging techniques on negative attitudes toward vaccines and likelihood to vaccinate future children. One technique Nyhan and colleagues used was to expose parents to scientific evidence that refutes a link between the measles, mumps, and rubella (MMR) vaccine and autism. Although exposure to such information decreased agreement with statements that the MMR vaccine is unsafe, exposure also decreased intention to vaccinate future children, particularly among those with already negative attitudes toward vaccines.

One possibility for this paradoxical effect is that the correction of misinformation may have threatened participants' sense of self. Self-affirmation generally involves reflecting on potentially unrelated values with the goal of strengthening the sense of self to prevent a person from reacting defensively, as if a health message is a personal attack on their self-worth. Individuals who self-affirm tend to see potentially threatening health messages as less threatening.

For the present article, 2 studies investigated the effectiveness of a self-affirmation exercise on vaccine safety beliefs and intent to vaccinate future children. In Study 1, a sample of 585 parents with at least one child under the age of 18 in the home participated in a survey. Participants were randomly assigned to one of 4 conditions in a 2 x 2 design. Participants read either correcting information refuting a link between the MMR vaccine and autism or a control passage about bird feeding. Additionally, participants either completed a self-affirmation exercise where they reflected on their personal values or were assigned to a control condition in which they reflected on least-personally-important values that might be important to others.

Study 1 found that participants exposed to the correcting information were less likely to believe that vaccines cause serious side effects, but no less likely to believe that the MMR vaccine causes autism. For parents with initially positive vaccine attitudes, there was no effect of condition on intent to vaccinate a future child. For parents with initially negative vaccine attitudes, self-affirmation was ineffective in the presence of correcting information and actually resulted in less intention to vaccinate in the absence of correcting information. This effect was partially replicated in Study 2 (N = 576), which provided no correcting information but otherwise followed the same procedure as Study 1.

Although previous research has found that self-affirmation exercises can be effective tools in other areas of health messaging (e.g., smoking, healthy eating), in those other health domains, participants are making health decisions for themselves, rather than for their children. In addition, although high-risk individuals (e.g., smokers, those with poor diet) may downplay the warnings in health messages (e.g., likelihood of disease), they are unlikely to strongly believe that smoking is good for them or that healthy eating is bad for them. In contrast, parents with negative vaccine attitudes may not only downplay the benefits of vaccines for their children, but also sincerely believe that vaccines are unsafe and dangerous for their children. Thus, although it was possible that self-affirmation would affect vaccine safety message acceptance in the same ways that it affects other health messages, the present investigation found that engaging in self-affirmation might have made parents more secure in their negative attitudes, particularly in the absence of any correcting information.

In short, the results provide no evidence for the hypothesis that self-affirmation would be an effective strategy. Given the relatively few participants with negative vaccine attitudes, the results provide weak evidence that self-affirmation may actually be detrimental for parents with initially negative vaccine attitudes.

According to the researchers, although the self-affirmation procedure appears detrimental, there are value-focused approaches that may be effective. Researchers in Australia developed a public health decision-making tool for parents that asks parents to rate how important various vaccine-specific values are, such as "if my child experiences a severe complication, I may feel guilty or responsible because I had them vaccinated". Using pre/post tests, the researchers found that using the decision-making aid increased parents agreement that they were "leaning toward" vaccination. Understanding how general values-affirmation versus the use of problem-specific (in this case, vaccine-specific) values affect decision making could be an avenue for future research. The current study also suggests further avenues of research for applying self-affirmation to health behaviours and decision-making, which are outlined at the end of the article.