Building Quality Through Structure: How Narrative Gaps and Conspiracy Beliefs Influence Health Message Coherence.

Ensuring quality health communication is especially challenging during crises, when evolving guidance may appear contradictory or incomplete. This study investigates how such contradictions-framed as narrative gaps-along with conspiracy beliefs, shape public evaluations of message quality. An online experiment with U.S. adults (N = 790) compared exposure to three contradictory Centers for Disease Control and Prevention (CDC) COVID-19 testing protocols versus a revised version designed for narrative coherence. Participants evaluated the messages on reliability and effectiveness, credibility, and trust in the government and scientists. Results showed that contradictory messages significantly undermined all three outcomes. Mediation analyses revealed that these effects operated primarily through participants' perception of narrative gaps rather than through active gap-filling or inference-making behaviors. COVID-19 conspiracy beliefs did not increase perceptions of gaps but moderated gap-filling: individuals with lower conspiratorial beliefs were more likely to generate explanations when inconsistencies appeared. These findings identify perceived incoherence as the key mechanism eroding trust and highlight the importance of designing coherent, gap-minimizing narratives to sustain credibility in rapidly changing information environments.