Why People Believe Fake News, Myths & Conspiracy Theories

Key themes

• The problem. Millions of Americans believe demonstrably false claims (birther myth, 9/11 truther myth, vaccine dangers, death panels). These are not fringe beliefs but widespread, often tracking with partisanship and identity. Myths shape real policy outcomes and undermine public health.
• Selective exposure. The common narrative of "echo chambers" trapping everyone is overstated: average Americans have centrist information diets. However, the politically active 10% with the most conservative media diets show extreme polarization and consume the vast majority of fake news (75% of Trump supporters visited pro-Trump fake news sites before 2016, vs. 20% of Clinton supporters).
• Selective acceptance and disconfirmation bias. Even when people encounter corrective information, they may reject it through motivated reasoning: we are all more skeptical of claims contradicting our worldview or identity. This bias is stronger among the educated (who can marshal more counterarguments). Myths become resistant to change when they become entangled with identity and values.
• Backfire effects. Some corrective interventions fail to change minds or paradoxically strengthen false beliefs among those predisposed to reject them (evidenced in early Bush-administration tax-cut experiments). The "illusion of truth effect" means repeated familiar claims feel more true over time, even if initially labeled false.
• What sometimes works. Graphical presentations of data (e.g., four independent temperature datasets all showing warming) are more effective than text at reducing climate-change denial, especially among Republicans. Leveraging trusted intermediaries (pediatricians for vaccine hesitancy) rather than direct public communication often works better, because source credibility matters more than facts alone. Signaling shared identity and values (e.g., "I'm a local mom who home-births and cloth-diapers and I vaccinate") can resolve perceived conflicts between values and health behavior.
• Prevention is better than correction. Once myths become widespread and entrenched (as the birther myth did), they are nearly impossible to debunk, even with the most definitive evidence (Obama's long-form birth certificate). Acting early to prevent myths from becoming politicized is far more effective than trying to correct them after they spread.
• Context matters. There is no universal message that works across all communities (e.g., vaccine hesitancy in San Francisco, the Amish community in Ohio, Orthodox New York, and Somali Minneapolis all require different approaches). Effective communication requires partnership with people who understand the specific community.

Nyhan's recommendations for practitioners and funders

1. Avoid reinforcing myths. When designing corrective materials, do not make the myth the most prominent element. Repeated exposure to a false claim, even when labeled false, can strengthen belief through the illusion-of-truth effect.
2. Use compelling formats. Graphical, visual, and narrative approaches can be more persuasive than abstract text, especially for audiences predisposed to dismiss textual corrections.
3. Leverage credible sources. Identify intermediaries and messengers trusted by the target audience. A pediatrician often carries far more weight than government health agencies. Experts who argue against their own political interests (e.g., Republican healthcare experts debunking the "death panel" claim) can be especially persuasive.
4. Signal identity alignment. Show that people within the target community hold both the desired belief and the values and identities the community cherishes. Resolve perceived conflicts between identity and health or factual behavior.
5. Act early. Prevent myths from becoming widespread and politically entangled before they calcify. Early intervention during the formation phase is far more effective than late-stage debunking.
6. Partner with communities and intermediaries. Direct public communication reaches few people and tends to reinforce existing beliefs in those it reaches. Work through trusted intermediaries with deep knowledge of the community.
7. Evaluate rigorously. Encourage grantees to partner with academics to run randomized controlled trials (RCTs) assessing intervention effectiveness. Celebrate failures as learning opportunities. Build the evidence base for what actually works rather than assuming any approach is effective.

Notes

A flagship talk on the psychology and research evidence surrounding belief formation and correction in the context of misinformation. Nyhan is among the leading empirical researchers on misperceptions and fact-checking effectiveness, known for rigorous randomized experiments. The talk is notable for its emphasis on the limits of direct correction (an important corrective to naive "just provide facts" approaches) and its practical recommendations grounded in behavioral science and psychological theory. The examples range from U.S. politics (birther myth, 9/11 truthers, climate denial) to health (vaccines, flu, healthcare policy) to international contexts (anti-Israel and anti-Semitic conspiracy beliefs in Egypt and Saudi Arabia), demonstrating the universality of these cognitive patterns. The emphasis on context-specificity and the role of identity in shaping factual beliefs is particularly valuable for practitioners and policymakers designing interventions.