For Digital Mass Persuasion, Exposure Matters More Than Persuasiveness

Concerns about digital mass persuasion—ranging from targeted political advertising and misinformation to AI-generated propaganda—have motivated extensive research on how persuasive such content is. Most studies assess impact by exposing individuals to messages and measuring changes in attitudes or behaviour. This essay argues that this focus is lacking. The mass persuasive impact of digital content depends not only on how persuasive a message is per person, but also on how many people are exposed to it. While both factors matter in principle, exposure varies far more than persuasiveness in practice. High-exposure content often reaches tens or hundreds of times more people than typical content, whereas highly persuasive messages are rarely tens or hundreds of times more persuasive than average ones. As a result, typically-persuasive content with high exposure generally has greater overall impact than highly persuasive content with only typical exposure. The essay develops this argument, reviews supporting evidence, explores implications for research and policy, and considers objections and boundary conditions.