This 2 (partisan opinion) x 2 (content source) x 2 (content valence) factorial experiment investigates how partisans' prior positions on two controversial issues of same sex marriage (N = 132) and guns on campus (N = 130) influence their perceptions about online content from either mainstream news source online (the Associated Press) or citizen blogs. Partisans' perceptions of the content included perceived bias and credibility. This study also explores how the perceptions affect partisans' online behaviors, including commenting on the content and subsequent information seeking.

       Theoretically, the study tests `hostile media effect' framework with a blog then investigates whether the effect differs when the same content appears on  a mainstream news source online (the Associated Press). The study also examines the relationship between the hostile media effect and partisans' online behaviors.

Participants were randomly assigned to one of the four conditions with each containing stimuli manipulated as either pro or anti on the issues on either a mainstream news source online (the Associated Press) or a blog.

      Similar to previous evidence of a relative hostile media effect in traditional printed news articles and national network broadcasts, this study found that online content also generated the effect regardless if content is produced by professional journalists or citizen bloggers. Partisans evaluated both mainstream online news and blog postings with opposite views as biased and less credible. Particularly, user-generated content, blog postings, generated a stronger relative hostile media effect than mainstream online news.   

        In addition, hostile media effect appeared to motivate partisans to comment on content that opposes their position to correct perceived bias, and amplify their own position. This study also confirms partisans' selective exposure to additional content that supports their position. However, the hostile media effect did not appear to enhance the tendency for selective exposure.  

         In their totality, partisan audiences' perceptions of bias and credibility in mainstream online news and blog postings in a hostile direction, followed by commenting and more information seeking, seems to reinforce partisanship rather than encourage consensus between supporters and opponents of the controversial issues.