Navigating the Complexity of Sustainability Communications: The Influence of Product Type, Media Type, and Brand Realism

ABSTRACT This study investigates when and why sustainability messages enhance consumer trust and persuasion, integrating product type, media channel, and brand realism within the Persuasion Knowledge Model (PKM) framework. Across three experimental studies (total N = 1153), we examine how consumers respond to sustainability claims in marketing communications for search, experience, and credence goods. Study 1 shows that sustainability messaging significantly increases trust for search and experience goods but has limited or negative effects for credence goods. Study 2 reveals that media type moderates these effects: digital media is more effective for low‐complexity (search) goods, whereas traditional media boosts trust for credence goods. Study 3 extends these findings by introducing brand realism (real vs. fictitious brands) and adds purchase intentions and brand attitudes as dependent variables. Results show that brand realism dampens persuasive effects for search and credence goods—likely due to increased skepticism—while enhancing outcomes for experience goods. Together, these studies demonstrate that the effectiveness of sustainability communication hinges on product evaluability, media credibility, and brand familiarity. Strategically, the most important implication is that sustainability messaging should be aligned with product category, media format, and brand context to maximize consumer trust, persuasion, and engagement.