| Our public life is riven by significant political disagreements on various public issues, and new information environments provide ample platforms for individuals to freely voice their own opinions, including dissonant or opposing views among the discussants. While online environments---and, in particular, social media---bring together interpersonal discussion and mediated communication, with interpersonal discussion potentially reaching a large number of audiences even beyond the original discussion networks, scholars have expressed anxiety around whether or not this new information environment decreases diversity in the expression of public opinion, a cornerstone of a deliberative democracy. However, research has yet to examine disagreement in online environments for non-election contexts.;My dissertation extends the scope of research on political disagreement into the context of disagreement across two politicized scientific issues. This dissertation begins with an examination of social-psychological factors and communication contexts that induce individuals' expression of disagreement in political discussions taking place on social media. Second, in the context of two politicized scientific issues, nanotechnology and genetically modified organisms (GMOs), I employ computer sentiment analysis to assess levels of expressed disagreeing content on Twitter across these two contested topics. Third, using the case of nanotechnology, I examine the impact of disagreement-seeking on scientific knowledge.;Results show that online hard news use is positively related to political disagreement expression on social media. Conflict avoidance and a perceived ambiguous climate of opinion suppress political disagreement expression on social media. In the context of nanotechnology and GMOs, expressing disagreement is a persistent phenomenon on Twitter, and the proportion of disagreeing content is higher in retweets about a relatively less polarized scientific issue, nanotechnology, than that in a more polarized scientific issue, GMOs. Meanwhile, consuming science news on social media has a positive effect on seeking disagreement, which is conducive to gaining scientific knowledge.;In conclusion, my research not only confirms and expands findings of political communication into science-related discussions, but also contributes to the literature on the connection between interpersonal communication and mediated communication. Further important theoretical, methodological, and practical contributions of the results are discussed and directions are suggested for future research. |
