Why do some people who embrace conspiracy theories simply hold those beliefs, while others act on them?
A new study published in the British Journal of Social Psychology identifies three characteristics that help determine when conspiracy beliefs are most likely to shape real-world behavior: how certain people are that the belief is true, how personally important they consider it, and whether they see it as “actionable” – useful for deciding what to do.
Across three studies involving more than 6,000 U.S. participants, researchers from the University of Pennsylvania’s Annenberg Public Policy Center (APPC) and Texas Christian University found that conspiracy beliefs alone were modestly associated with behavior. But when those beliefs were held with greater certainty or importance, they became more robust predictors of attitudes toward behaviors (for example, favorability toward Covid-19 vaccination). Importantly, the impact of certainty or importance was further amplified when people viewed their conspiracy beliefs as relevant guides for action. In turn, attitudes toward behaviors predicted behaviors ranging from Covid-19 vaccination decisions to political participation.
The findings suggest that understanding the influence of conspiracy theories requires looking beyond what people believe to consider how they hold those beliefs. That is, not all conspiracy beliefs are created equal, with some being more impactful as they are held with more certainty, importance, or actionability.
“People may endorse a conspiracy theory to the same extent, but that does not necessarily mean that it will translate into behavior to the same extent,” said lead author Javier A. Granados Samayoa , assistant professor of psychology at Texas Christian University and a former APPC postdoctoral fellow. “Our findings suggest that our beliefs have different qualities that matter for determining what their impact will be. Specifically, we show that conspiracy beliefs are much more likely to influence behavior when people are highly certain those beliefs are true or see them as personally important. Viewing them as useful for making decisions further amplifies this tendency.”
The study’s senior author, Dolores Albarracín, APPC’s director and the Amy Gutmann University Professor at the University of Pennsylvania, said the findings point to new ways of thinking about interventions.
“Simply correcting misinformation is not enough,” Albarracín said. “If we want to reduce the harmful effects of conspiracy beliefs, we need to understand the psychological qualities that give those beliefs their power to motivate behavior.”
The researchers tested their theory in three large studies examining conspiracy beliefs in different settings. One study investigated the “great replacement” conspiracy theory – the idea that there is an intentional effort by powerful elites to “make White Americans a minority” – and attitudes toward immigration-related behaviors. A second focused on conspiracy theories about Covid-19 vaccines and participants’ actual vaccination status. A third examined conspiracy beliefs about a so-called deep state undermining Donald Trump and followed participants over three months to measure behaviors including seeking and sharing political information, donating to campaigns, volunteering, and attending political rallies.
Across all three studies, the researchers found the same pattern: conspiracy beliefs were more strongly associated with behavioral attitudes and, ultimately, behavior when participants held those beliefs with greater certainty or regarded them as especially important. However, those relationships became consequential when participants believed the conspiracy theories were useful for guiding their own decisions – a characteristic the researchers describe as “perceived actionability.” In turn, those attitudes predicted actual behavior.
The authors say the findings have implications beyond conspiracy theories. The same psychological processes may help explain when other kinds of beliefs become powerful enough to influence behavior, suggesting that future interventions should address not only belief accuracy but also people’s certainty in those beliefs, the importance they attach to them, and whether they view them as actionable.
The study, “Belief strength and the attitudinal and behavioural correlates of conspiracy beliefs ,” by Javier A. Granados Samayoa and Dolores Albarracín, was published May 31, 2026, in the British Journal of Social Psychology. The research was supported in part by the National Institutes of Health and by an endowment from the Communication Science Division of the Annenberg Public Policy Center.
British Journal of Social Psychology
People
Belief strength and the attitudinal and behavioural correlates of conspiracy beliefs
31-May-2026