Graduate Studies, UNL

 

Dissertations and Doctoral Documents from University of Nebraska-Lincoln, 2023–

First Advisor

Ingrid Haas

Degree Name

Doctor of Philosophy (Ph.D.)

Committee Members

Elizabeth Theiss-Morse, John Hibbing, Maital Neta

Department

Political Science

Date of this Version

2025

Document Type

Dissertation

Citation

A dissertation presented to the faculty of the Graduate College of the University of Nebraska in partial fulfillment of requirements for the degree Doctor of Philosophy (Ph.D.)

Major: Political Science

Under the supervision of Professor

Lincoln, Nebraska, December 2025

Comments

Copyright 2025, the author. Used by permission

Abstract

This dissertation investigates how echo chambers emerge on social media by shifting the lens from aggregate patterns of information exposure to moment-by-moment, individual level interaction decisions between peers. I theorize that selective exposure online is not only about what content people consume or avoid, but also about selective social exposure—accepting, rejecting, or sharing with the sources of that content—guided by sociopolitical identity, ideological distance (ID), and discrete emotions. To test this, I employ two survey experiments using real tweets varying in ideological extremity and measure user’s likelihood to Block, Follow, Retweet, or reply, alongside self-reported emotional reactions and ID between sender and receiver. Study 1 shows acceptance into one’s network is best explained by the sender’s extremity and perceived in-group. Emotions are shaped by in-group membership, and once an emotion is felt, group membership no longer moderates the emotion’s link to outcomes. These findings provide support for sociopolitical identity and emotion, both independently and jointly, influencing social network construction online. Study 2 experimentally induces anger, anxiety, or enthusiasm before exposure to ideologically varied tweets. While anxiety increases openness to in-group members, both anxiety and anger generally suppress sharing and acceptance, complicating expectations from Affective Intelligence Theory; enthusiasm could not be reliably induced. Across conditions, ID robustly shapes outcomes, with in-group favoritism driving network choices more than out-group rejection, complicating common expectations associated with affective polarization. The studies support a dynamic account of echo chamber formation; individuals use rapid, affect laden judgements about both content and its sender to determine future social interactions, thereby creating conditions under which ideologically homogenous networks become more likely. Theoretical implications extend selective exposure research from media choice to social selective exposure, highlighting how sociopolitical identity and emotion shape acceptance, rejection, and sharing decision-making on social media. Limitations include platform scope and a survey design that carries no real-world cost. I conclude by discussing implications for theories employed by political science and echo chamber scholars and outline future work on platform affordances and user experience changes (e.g., retweets, character limits, algorithmic timelines) and recommend field or longitudinal designs to assess behavioral persistence.

Advisor: Ingrid Haas

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