Beyond the Platform: How Narrative Style Drives Authenticity Perceptions, Parasocial Relationships, and Purchase Intentions in Cross-Platform Influencer Advertising

The proliferation of influencer marketing across socially distinct platform environments has generated competing theoretical accounts of advertising effectiveness: one privileging platform-specific affordances as the primary shapers of audience response, the other positioning narrative strategy as the dominant driver. This study resolves this theoretical tension through a 3 (platform: TikTok, Instagram, WeChat Moments) × 2 (narrative style: polished vs. raw) between-subjects online experiment (N = 362) conducted among Thai-local and Thai-Chinese audiences in Thailand. Drawing on narrative transportation theory, influencer authenticity frameworks, and parasocial relationship theory, we examined how platform type and narrative style independently and jointly shape transportation, authenticity perceptions, parasocial relationship (PSR) strength, ad attitudes, and purchase intentions. Raw narrative style produced large, consistent advantages across all five outcomes: transportation (d = 0.74), authenticity perceptions (d = 0.97), PSR (d = 1.06), ad attitudes (d = 0.55), and purchase intentions (d = 0.96)—all p < .001. Platform type produced only a marginal effect on ad attitudes (η²p = .020), with TikTok generating higher scores than WeChat (Tukey HSD, p = .044). Platform × narrative style interactions were non-significant for four of five outcomes; a marginal interaction emerged for transportation (p = .056), with TikTok amplifying the raw narrative transportation advantage. Bootstrap mediation analyses (k = 5,000) indicated that authenticity perceptions did not significantly mediate the narrative style–outcome pathway. Cultural orientation did not moderate the narrative–PSR relationship. Findings challenge platform-determinist assumptions, establish cross-platform narrative primacy, and identify TikTok as a context-amplifying affordance environment for transportation-based persuasion.