Multi-element Persuasion in Social Media Health Communication: Synergistic and Trade-off Effects

Health messages on social media are typically constructed through combinations of source cues, appeals, frames, and evidence, which jointly shape communication and persuasive effects. However, prior research has largely focused on single elements or simple pairwise interactions, offering insufficient insight into how multiple elements operate together in real-world digital environments. To address this gap, this study adopts a systems perspective to examine multi-element message combinations. Using 1.8 million health-related Weibo posts, we apply clustering analysis to identify recurring combinations and assess their relationships with communication effects. First, four recurring element combinations are identified: Institutional Authority, Narrative, Assertive Appeal, and Contextual Expression. These combinations function as core structures organized around two key elements. Second, stronger communication effects depend not only on core structures but also on peripheral elements aligned with these structures, with combinations of two to four peripheral elements generally showing greater advantages. Third, the optimal level of peripheral complexity varies with source influence, indicating that environmental factors condition the relationship between message combinations and communication effects. These findings show that communication and persuasive effects are shaped by synergies and trade-offs among multiple persuasive elements. Based on this, the study proposes a Core-Periphery-Environment framework to explain how message combinations generate communication effects with persuasive implications on social media. The study extends research from isolated elements to systems combinations and offers practical implications for health communication.