Explicating the Hostile Media Perception: How source credibility influences partisans' responses to balanced news coverage of health policies
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This dissertation proposed that source credibility research provides explanations for why partisans, or people with extreme positions on an issue, see balanced news coverage as biased against their own position (i.e., exhibit hostile media perception). The effects of three dimensions of source credibility (trust, competence, and goodwill) were considered. Partisans were expected to see neutral news articles authored by untrustworthy sources and sources lacking in goodwill as biased against their position, and perceptions of bias were expected to be more intense if untrustworthy sources and sources lacking in goodwill were seen as competent. This dissertation also hypothesized that source credibility perceptions could account for prior research that finds partisans charge bias against neutral news content said to be authored by journalists (but not college students) and neutral news content said to be authored by outgroup (but not an ingroup) members.
Three experiments in two health policy contexts (increasing taxes on sugar-sweetened beverages and requiring the human papillomavirus [HPV] vaccine) were conducted. The results of the three experiments provide evidence that the influence of source credibility on hostile media perception is dependent upon (1) partisan position (i.e., supporters vs. opponents), (2) extremity of partisanship, and (3) health policy context. In the context of increasing taxes on sugar-sweetened beverages, several hypotheses were supported. In Experiment 1, partisan supporters perceived news to be biased against their position when the source was said to be lacking in goodwill. In Experiment 2, source trust and competence were predictive of hostile media perception for more extreme partisan supporters. In Experiment 3, trust mediated the relationship between source group membership and hostile media perception for more extreme partisans. In the context of requiring the HPV vaccine, competence was a significant predictor of hostile media perception in Experiment 1 and a significant mediator in Experiment 2. Finally, distrust of journalists or sources is perhaps necessary, but not sufficient, for hostile media perception to manifest, and distrust may not serve as an explanation for bias in all circumstances.
Theoretical and practical implications, limitations, and directions for future research related to source credibility and hostile media perception are discussed.