Certainty, personal importance and a newly measured quality called “perceived actionability” help explain when conspiracy beliefs spill into real-world behavior.

Two people can agree, to exactly the same degree, that a secret cabal is pulling the strings. One shrugs and goes about her day. The other skips a vaccine, shows up at a rally or writes a check to a campaign. For years, researchers who study conspiracy theories have struggled to explain that gap. A new study offers a partial answer: what matters is not only what people believe, but how they hold those beliefs.

Writing in the British Journal of Social Psychology, psychologists Javier A. Granados Samayoa of Texas Christian University and Dolores Albarracín of the University of Pennsylvania’s Annenberg Public Policy Center report that conspiracy beliefs are far more likely to shape behavior when people are certain they are true, consider them personally important and, crucially, see them as useful guides for deciding what to do.¹

“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 Granados Samayoa, an assistant professor of psychology at TCU and a former APPC postdoctoral fellow. “Our findings suggest that our beliefs have different qualities that matter for determining what their impact will be.”²

A weak link that needed explaining

Conspiracy beliefs have been tied to a long list of troubling outcomes. Earlier research has linked them to lower contraception use, vaccine hesitancy and voting decisions, as well as to greater prejudice, opposition to science and support for violence.^3,4 Experiments have shown that simply exposing people to anti-vaccine conspiracy theories can dampen their intentions to vaccinate.⁵

Yet when the evidence is pooled, the average association between conspiracy beliefs and behavior turns out to be small, and it varies widely from one study to the next. That inconsistency is what motivated the new work.

Granados Samayoa and Albarracín borrowed a framework from a well-developed corner of social psychology known as attitude strength. Decades of research have shown that attitudes held with certainty, or regarded as important, predict behavior far better than flimsy ones.^6,7 A meta-analysis Albarracín co-authored in 2006 found that attitudes can be strong predictors of future behavior, particularly when they are formed in ways that make them confident and stable.⁸ Classic work by Martin Fishbein and Icek Ajzen, meanwhile, describes attitudes as being built from the beliefs that underlie them.⁹

The researchers’ model stitches these ideas together. Beliefs shape attitudes toward specific behaviors, and those attitudes drive behavior. But how tightly the first link holds depends on what the authors call “belief strength,” a bundle of three self-assessments: certainty, importance and perceived actionability.

That last quality is new to the field. It captures whether a person sees a belief as relevant and useful for their own decisions. A conspiracy theory about a stolen election, the authors observe, suggests a whole menu of actions, from posting online to attending rallies, donating and volunteering. A theory that the moon landing was faked suggests little beyond sharing it on the internet.

Three studies, one pattern

The team tested the model on 6,082 U.S. adults across three studies, two of them drawn from nationally representative probability samples.

The first, pre-registered study recruited 1,959 participants online and asked about the “great replacement” conspiracy theory, the claim that secretive, powerful groups are deliberately using immigration to make White Americans a minority. Stronger belief predicted more favorable attitudes toward anti-immigration actions, such as voting for a politician who backs strict anti-immigrant policies. When participants saw the belief as highly actionable, the link was roughly four times stronger among highly certain believers than among uncertain ones. When actionability was low, that gap narrowed considerably.

The second study surveyed 2,572 adults in December 2022 about claims that COVID-19 vaccines contain microchips or alter DNA. Belief predicted more negative attitudes toward vaccination, and those attitudes, in turn, strongly predicted whether people had actually received a shot. Once again, the pathway from belief to behavior was strongest when participants rated the issue as important and considered their beliefs useful for making decisions.

The third study followed 1,551 people for about three months in 2023. Participants reported whether they believed a “deep state” of government officials was working illegally to undermine Donald Trump and his supporters, along with their attitudes toward five actions: seeking and sharing related information, donating, volunteering and attending rallies. Attitudes measured at the outset predicted how often people had actually done those things three months later. And the same three-way pattern reappeared.

Notably, actionability on its own did not reliably change the link between belief and attitude. Its role, the authors argue, is to potentiate beliefs that are already held with certainty or importance, acting as a kind of force multiplier.

“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,” Granados Samayoa said. “Viewing them as useful for making decisions further amplifies this tendency.”²

Beyond fact-checking

The findings carry practical implications for anyone trying to blunt the real-world harms of conspiracy thinking. Most interventions focus on content: debunking false claims, warning people about manipulation tactics or labeling dubious posts. The new results suggest that the qualities surrounding a belief may be equally important targets.

“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.”²

The authors point to two levers: raising doubt to lower a person’s certainty, and making a belief seem less relevant or useful as a basis for action. That approach dovetails with self-validation theory, developed by Pablo Briñol and Richard Petty, which holds that thoughts people regard as valid carry outsized weight in shaping their judgments.¹⁰

The researchers are candid about the limits. All three studies are correlational, and the authors explicitly caution readers against drawing causal conclusions, acknowledging that the statistical mediation models they used have drawn sustained methodological criticism.¹¹ The vaccine items in the second study also arguably measured endorsement of misinformation rather than conspiracy theories proper. Yet the fact that the same pattern held there hints that the model may apply to beliefs well beyond conspiracies.

That broader reach may be the study’s most significant contribution. Psychologists have long known that attitudes vary in strength. This work argues that beliefs do too, and that the difference between a belief someone merely holds and one they act on may come down to how sure they are, how much it matters to them and whether it tells them what to do next. As the authors put it, “not all beliefs are created equal.”¹

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Endnotes

1. Granados Samayoa, J. A., & Albarracín, D. (2026). Belief strength and the attitudinal and behavioural correlates of conspiracy beliefs. British Journal of Social Psychology, 65, e70104. https://doi.org/10.1111/bjso.70104
2. Annenberg Public Policy Center of the University of Pennsylvania. (2026, July 29). New study explains when some conspiracy beliefs can lead to action [Press release]. EurekAlert! https://www.eurekalert.org/news-releases/1137951
3. Douglas, K. M., Uscinski, J. E., Sutton, R. M., Cichocka, A., Nefes, T., Ang, C. S., & Deravi, F. (2019). Understanding conspiracy theories. Political Psychology, 40(S1), 3–35. https://doi.org/10.1111/pops.12568
4. Bogart, L. M., & Thorburn, S. (2005). Are HIV/AIDS conspiracy beliefs a barrier to HIV prevention among African Americans? JAIDS Journal of Acquired Immune Deficiency Syndromes, 38(2), 213–218. https://doi.org/10.1097/00126334-200502010-00014
5. Jolley, D., & Douglas, K. M. (2014). The effects of anti-vaccine conspiracy theories on vaccination intentions. PLoS One, 9(2), e89177. https://doi.org/10.1371/journal.pone.0089177
6. Petty, R. E., & Krosnick, J. A. (Eds.). (1995). Attitude strength: Antecedents and consequences. Lawrence Erlbaum Associates.
7. Howe, L. C., & Krosnick, J. A. (2017). Attitude strength. Annual Review of Psychology, 68(1), 327–351. https://doi.org/10.1146/annurev-psych-122414-033600
8. Glasman, L. R., & Albarracín, D. (2006). Forming attitudes that predict future behavior: A meta-analysis of the attitude-behavior relation. Psychological Bulletin, 132(5), 778–822. https://doi.org/10.1037/0033-2909.132.5.778
9. Fishbein, M., & Ajzen, I. (1975). Belief, attitude, intention, and behavior: An introduction to theory and research. Addison-Wesley.
10. Briñol, P., & Petty, R. E. (2022). Self-validation theory: An integrative framework for understanding when thoughts become consequential. Psychological Review, 129(2), 340–367. https://doi.org/10.1037/rev0000340
11. Rohrer, J. M., Hünermund, P., Arslan, R. C., & Elson, M. (2022). That’s a lot to PROCESS! Pitfalls of popular path models. Advances in Methods and Practices in Psychological Science, 5(2), 1–14.