Pro-Vaccination Subjective Norms Moderate the Relationship between Conspiracy Mentality and Vaccination Intentions

"Although correlational, these data raise the possibility that pro-vaccination views of friends and family can be leveraged to reduce vaccine hesitancy."

Research has shown that people who endorse conspiracy beliefs to a stronger extent have more negative attitudes toward vaccination. However, this finding is largely unconnected to the existing literature on the predictors of vaccination attitudes and intentions. To close this gap, the current research aims at integrating research on conspiracy beliefs with the theory of planned behaviour (TPB), which incorporates perceptions of what close others think (the subjective norm) - e.g., about vaccination. The study examines two competing predictions: Are those high in conspiracy mentality immune to subjective norms (Hypothesis A), or do subjective norms mitigate the role of conspiracy mentality in predicting vaccination intentions (Hypothesis B)?

"First, it is possible that those high in conspiracy mentality will be particularly unaffected by the attitudes of close others. Believing in conspiracy theories [i.e., drawing on explanations for important events that involve secret plots by powerful and malevolent groups] usually goes hand in hand with believing non-normative explanations for events and with challenging widely accepted knowledge....Thus, conspiracy theories seem to be especially appealing to people who want to stand out from the masses." In contrast to Hypothesis A, it is possible to make the case "that subjective norms will moderate the negative relationship between conspiracy mentality and vaccination intentions. The subjective norm relates to opinions of close others such as friends and family and does not necessarily represent widely accepted knowledge [Hypothesis B]."

The researchers conducted five studies among 1,280 Germans to test these hypotheses across several vaccination contexts (some real, some fictitious; some in the lab, some online). The five studies centred around: vaccination against an unspecified disease in a foreign country one wants to travel to ("travel vaccination"; Studies 1, 2, and 5), vaccination of one's own (imagined) child against hepatitis B ("child vaccination"; Studies 1, 2, and 5), vaccination against COVID-19 once a vaccine becomes available (Studies 3 and 5), seasonal vaccination against influenza (Study 4), and vaccination against the tick-borne encephalitis virus (TBEV; Study 5).

The researchers measured conspiracy mentality, vaccination intentions, subjective norms, attitudes toward vaccination, and perceived behavioural control. [The TPB argues that behavioural intentions are driven by three components: the subjective norm (as discussed above), the attitude toward the behaviour (i.e., whether one thinks that the behaviour is favourable or unfavourable), and perceived behavioural control (whether one perceives performing the behaviour to be under one's volitional control, similar to self-efficacy).]

For the travel vaccination, the child vaccination, the COVID-19 vaccination, as well as the TBEV vaccination, an interaction of conspiracy mentality and subjective norm emerged. In all these cases, conspiracy mentality predicted vaccination intention to a lesser degree, when subjective norms were perceived as high as compared to low. However, for the influenza vaccination, there was no interaction effect of conspiracy mentality and subjective norm on vaccination intention. In addition, this was the only vaccination where no relationship between conspiracy mentality and vaccination intention occurred. Thus, there was no relationship in the first place that could have been moderated by high subjective norms.

A merged analysis across the studies revealed an interaction effect of conspiracy mentality and subjective norm on vaccination intentions. When subjective norm was high (i.e., when participants perceived that close others approved of vaccines), conspiracy mentality no longer predicted vaccination intentions. Speaking against Hypothesis A, conspiracy mentality did not weaken the relationship between subjective norm and vaccination intentions. To the contrary, conspiracy mentality only predicted lower vaccination intentions when the subjective norm to vaccinate was low (consistent with Hypothesis B). When the subjective norm was high, conspiracy mentality did not play a role with regard to vaccination intentions.

Implications for how to deal with vaccination hesitancy that has its roots in conspiracy beliefs (as appears to be the case for the COVID-19 vaccines, for example) include:

• While much effort in both research and practice is put into debunking conspiracy theories or persuading those who believe in them, a different (probably complementary) strategy could be focusing on the fact that considering the attitudes of friends and families seems to be highly important: When these close others convey the impression that getting vaccinated is what they think a person should do (i.e., the norm), conspiracy mentality no longer predicts vaccination intentions. Personalised health communication might be more successful than communication by health authorities.
• When communicating with close others who endorse conspiracy beliefs about the COVID-19 vaccine, for example, a first step could be revealing one's own positive vaccination intentions. Rather than trying to reduce conspiracy beliefs, signalling a positive subjective norm might be a means of circumventing the negative impact of a conspiracist tendency on vaccination intentions. The researchers note that, while subjective norms might be helpful to reach those on the edge when it comes to conspiracist beliefs, this approach might be less effective among those who are deeply enmeshed in fringe conspiracy communities.

In conclusion, this research provides evidence that "conspiracy mentality and subjective norm conjointly predict vaccination intentions. However, it is not conspiracy mentality that reduces the impact of subjective norm as was initially expected. Rather, it is the subjective norm that determines whether or not the conspiracy mentality negatively predicts vaccination intentions. Conspiracy mentality negatively predicts vaccination intentions only when the norms set by close others is not in favour of vaccination. Thus, keeping social bonds instead of rejecting people who are susceptible to conspiracy beliefs should be encouraged."