Algorithmic Power, Visibility-Based Credibility, and Audience Engagement with Cause-Related Content: An Audience-Side Test of Platform-Mediated Communication

Platform algorithms increasingly determine which messages reach audiences on social media, yet most communication research on cause-related content has examined source-side characteristics rather than how audiences interpret the platform itself. This study tests whether perceived algorithmic power shapes engagement with cause-related content directly, and whether that relationship is partially mediated by a visibility-based credibility heuristic — the inference that messages a platform makes prominent are messages worth attending to. Survey data were collected from 580 social media users across five English-speaking markets. Confirmatory factor analysis supported a clean three-factor measurement model with strong reliabilities (α = .77–.83) and clear discriminant validity (HTMT < .42); Harman's single-factor test indicated common-method variance was unlikely a major concern. Regression analyses with controls supported all four hypotheses: perceived algorithmic power predicted both engagement (β = .34, p < .001) and visibility-based credibility (β = .30, p < .001), and visibility-based credibility independently predicted engagement (β = .20, p < .001). A bias-corrected and accelerated bootstrap mediation analysis (5,000 resamples) produced a significant indirect effect (ab = .061, 95% BCa CI [.035, .092]), indicating partial mediation accounting for approximately 18% of the total effect. Findings suggest that audiences treat platform-curated visibility as a relevance cue, with implications for how applied communicators design cause-related campaigns under algorithmic conditions.