This study used rigorous meta-analytic approaches to analyze empirical agenda-setting studies published from 1972 to 2015, and 67 studies that met the inclusion criteria for analysis produced a moderate grand mean effect size of 0.487. A multiple regression analysis revealed one most notable predictor that classified the basis for the study correlation as either content categories or survey participants. A multiple regression of a subgroup using content categories produced homogeneity. The mean effect size for these studies was 0.51. This is an indication of consistency in findings across agenda-setting studies and the presence of strong news media’s public agenda-setting effects.

News outlets use social media, especially Facebook, for content distribution and engagement. This exposes consumers to user comments before reading a news article, creating an environment where audiences judge content prior to reading the story. In response to Perloff's (2015) call for research exploring how social media cultivate hostile media effects, this work examines the effects of viewing comments prior to reading a news story on perceptions of bias and credibility. This application tests across issue topics and is not limited to strong partisans or individuals with high issue involvement to test effects on a broader population. Results show comments under Facebook news teasers influence perceptions of bias and credibility. Specifically, those exposed to congruent opinions reported lower perceptions of bias and higher perceptions credibility than exposed to incongruent opinions. Results extend the hostile media bias theory by focusing on all audiences and prescribes practical implications for news practitioners. K E Y W O R D S credibility, Facebook, hostile media bias, online comments The hostile media phenomenon contends that individuals, especially

News outlets rely on social media to freely distribute content, offering a venue for users to comment on news. This exposes individuals to user comments prior to reading news articles, which can influence perceptions of news content. A 2 × 2 between-subject experiment (N = 690) tested the hostile media bias theory via the influence of comments seen before viewing a news story on perceptions of bias and credibility. Results show that user comments induce hostile media perceptions.