Where belief is filtered: how truthfulness and source credibility shape trust, skepticism, and worry in vaccine communication

This study examines how true versus false messages shape trust in cancer-vaccine information on social media, alongside skepticism and worry, and tests the moderating roles of source credibility and deception-detection self-efficacy. In a 2 × 2 between-subjects experiment (N = 210), participants viewed a simulated cancer-vaccine post and reported their responses. The findings show that true messages elicit significantly higher levels of trust and lower levels of skepticism and worry than false messages, and that source credibility amplifies the positive effect of truthfulness on trust. Source credibility did not, however, moderate skepticism or worry, and deception-detection self-efficacy conditioned skepticism but not trust or worry. Higher confidence in detecting deception predicted greater skepticism, suggesting that perceived evaluative competence can intensify scrutiny rather than foster trust. Drawing on experimental evidence from the high-stakes, underexamined context of cancer vaccines, this study advances understanding of trust formation in digital science communication by showing that message truthfulness and source credibility operate through distinct processing routes: systematic evaluation of content and heuristic reliance on source cues, respectively. The findings offer theoretically grounded guidance for practitioners and policymakers seeking to counter misinformation and strengthen public confidence in emerging biomedical innovations.