Friends that matter [electronic resource] : how social transmission of elite discourse shapes political knowledge, attitudes, and behavior
Keywords: Communication.

This dissertation examines the social processes and effects that occur when individuals socially transmit elite opinion, sharing and/or endorsing such content in a public or semi-public setting. Chapter 1 defines social transmission, discussing the signals people send when socially transmitting elite discourse. It speculates as to how we should expect social transmission to affect the mix of political individuals encounter, the formation of social norms about politics, and political behavior. Chapter 2 explicates why people should be expected to utilize socially transmitted signals as heuristic cues when selecting and evaluating content---these signals enable people to find desirable and/or socially relevant articles with little cognitive burden. It presents evidence from a web experiment showing that the presence of aggregated social signals endorsing content increase the number of articles people consume and that genuine but not fake social signals result in a more positive evaluation of the reading experience. Chapter 3 establishes the relative impact of the social signals compared to partisan selectivity, showing in two experimental studies that aggregated social signals affect selection to a much greater degree than partisan agreement with the source-brand (i.e., Fox News, MSNBC), and that when social signals and partisan source cues are presented simultaneously, partisan selectivity disappears.\footnote{Chapter 3 replicates key findings in chapter 2 with much larger samples.} Chapter 4 extends this work to content socially transmitted from one individual to another, which depends on the relationship between the sharer and the recommender. It employs an innovative ecologically valid design that cleanly dissociates the effect of tie strength from homophily (a set of similar characteristics and interests in common between the sharer and reader that normally confounds such attempts) on selectivity. Chapter 5 extends this work to the realm of social identity and group membership---examining how group level-attributes of the person sharing content affect how readers select and process it. It demonstrates how reading identical content shared by different group members affects subsequently measured political preferences on the issue. The remaining chapters deal with the real-world political implications of these processes. Chapter 6 examines real world networks of socially transmitted elite discourse, and how these vary based on partisan affiliation. It examines every instance thereof during a six month period on the largest social media platform, Facebook, and demonstrates that individuals are more likely to consume and endorse content endorsed by ideologically aligned sources, though a substantial amount of consumption and discussion occurs across ideological lines. Finally, Chapter 7 examines the hypothesis that sharing political content in social media media signals the importance of being involved in politics and thus activates various pro-social political norms. A large scale, 72-day field experiment demonstrates that an increase in exposure to socially transmitted political information increased the salience of politics, increased rates of downstream sharing of political content, led to stronger opinions about policies and politicians, and increased voter turnout.