Going with the Grain of Cognition: Applying Insights from Psychology to Build Support for Childhood Vaccination

"[T]here is...a wealth of psychological literature outlining optimal ways to design interventions to effectively shift behavior that may be relevant to vaccine hesitancy."

The authors of this paper contend that, while the drivers of vaccine hesitancy are well documented, effective intervention strategies for addressing the issue are lacking. Here, they argue that this may be because existing strategies have been guided more by intuition than by insights from psychology regarding how people think and act, as well as by the erroneous assumption that humans act rationally. In the paper, they highlight the potential pitfalls of this approach by providing examples where interventions based on these assumptions have backfired, discuss why they backfired, and consider how such backfire effects might be averted.

In the literature, hesitancy has been understand to be driven by 3 factors: complacency resulting from low risk perceptions of vaccine-preventable diseases; a lack of convenience arising from insufficient access to vaccine services; and low confidence due to concerns about the safety and/or effectiveness of vaccines and the legitimacy of the services that deliver them (the "3Cs" model). Here, the researchers focus on hesitancy based on confidence because they see it as a tipping point toward vaccine refusal or acceptance.

As reported here, most strategies for increasing confidence in immunisation have been based on the Information Deficit Model (IDM) of science communication. This model is predicated on the assumption that humans are rational and that public misconceptions of science arise due to insufficient knowledge. On this approach, the solution to vaccine hesitancy is to provide hesitant parents with more scientific facts; however, research has found that knowledge is rarely a good predictor of vaccination acceptance, and interventions that seek to inform or educate hesitant parents have little or no impact on vaccine confidence.

The researchers argue that a different approach is required - one that recognises that there are complex cognitive, social, and affective processes that need to be taken into consideration when crafting interventions. As they explain, intervention strategies that disregard these complex psychological processes, such as those based on the IDM, may even inadvertently increase parents' resistance to vaccination. Table 1 in the paper provides a concise overview of these backfire effects. The fourth and fifth columns of the table summarise, respectively, the degree of evidence for these backfire effects (+, weak evidence; ++, moderate evidence; +++, strong evidence) and whether this evidence is direct (observed in a vaccination context), indirect (observed in a context other than vaccination), or a combination of the two.

In brief, the backfire effects include:

• In order to debunk a myth, it seems logical to expose people to the myth so they know what you are referring to. Indeed, a common strategy for highlighting false information is to present myths juxtaposed with relevant facts. Yet, dubbed the familiarity backfire effect, it seems that exposure to the myth can actually boost familiarity with the misinformation, paradoxically increasing the likelihood that people will recall it and assume it to be true.
• While it may seem intuitive to present many counterarguments to debunk a myth, processing many arguments is more cognitively taxing than processing a few, which renders it less likely that the information will be integrated into individuals' mental models, especially when compared to a simple and compelling myth. This is called the overkill backfire effect.
• The attitude polarisation backfire effect happens as follows: When confronted with belief-incongruent information, people tend to selectively call to mind evidence and arguments in opposition to this information, leading them to cling to their original beliefs even stronger than before. For example, in a study of public acceptance of evidence regarding the human papillomavirus (HPV) vaccine, people were more likely to discredit information about the safety and effectiveness of the vaccine when the information was framed in a way that clashed with their pre-existing worldviews.
• It has also been found that, when attitudes or beliefs are viewed as sacred (part of one's deeply held beliefs), behaviour grounded in those attitudes or beliefs tends to be viewed as a moral rule that cannot be violated, rather than a preference that can be subject to cost-benefit analysis. These insights are applicable to moves by various governments to withhold welfare payments or restrict access to other goods and services from parents who choose not to vaccinate their children. It may be that the introduction of monetary value to what is otherwise viewed as a moral issue has the potential to lead vaccine-hesitant parents to become more entrenched in their beliefs.
• The social norms backfire effect involves highlighting an undesirable behaviour as being regrettably frequent, which inadvertently communicates a descriptive norm signaling that the behaviour is common, and therefore normal and approved of by others. That is, it may be that public campaigns highlighting vaccine hesitancy as a growing problem lead people to overestimate the extent to which parents actually distrust vaccines, thereby decreasing their own confidence.
• Messages that criticise a particular group, such as vaccine-hesitant parents, can lead that group to rally together and cling to their beliefs more strongly than before.
• Persuasive messages that induce fear to encourage individuals to accept the messages' recommendations can potentially backfire by triggering defensive and avoidant responses. Research has shown that the possibility of a fear appeal backfiring may be increased if audiences perceive that they are unable to effectively adopt the messages' recommendations.

That said, according to the authors, given what we know about how people's attitudes and decisions are systematically influenced by (1) how they remember information (cognitive), (2) their group identities and deeply held beliefs (social), and (3) their emotional responses (affective), effective interventions to build confidence in childhood vaccination can potentially be crafted to harness these fundamental aspects of human psychology.

For example, in order to avoid the familiarity backfire effect, it is best to begin by stating the facts; then introduce the myth; then debunk it; and finally replace the myth with a scientific fact. Crucially, the myth should never be repeated. Similarly, to avoid the overkill backfire effect, communicators should present just a few counterarguments to a myth.

Other approaches suggest bypassing the facts altogether. For example, opposition to vaccination tends to be based on a preference for a natural, alternative lifestyle, as well as the belief that governments should not intrude into one's personal life. It may be possible to redefine vaccination as congruent with such values; there is some promising work in this vein, discussed in the paper.

Another possiblility involves taking advantage of people's tendency to act in accordance with perceived social norms. Despite growing parental concern, vaccination rates are still high in most communities (90-95%). Communicating this high level of community endorsement may be an effective approach for leveraging support for vaccination. Research on social identity theory further suggests that, if a counter-attitudinal message is communicated by an in-group source, it is more likely to be accepted.

Finally, previous research suggests that fear appeals can be used productively in 2 ways: (i) by incorporating a powerful self-efficacy-promoting element; and (ii) by getting message recipients to self-affirm by listing positive attributes about themselves or reflecting on their own cherished values.

In conclusion: "Our strategies must go with the grain of cognition - they must be crafted in a way that acknowledges how people actually think and act, rather than how they ought to. In the same way that vaccination programmes rely on rigorous medical science, so too should vaccination interventions be informed by the best available evidence from the psychological sciences."