(iPoster) Echoes or Amplifiers? Elite-Public Causality in the Black Lives Matter Protests

• In Event: Poster Sessions: Polarization, Identity, and Democratic Vulnerability & Political Communication I
  In Poster Session: Poster Session: Political Communication I

Abstract

The 2020 Black Lives Matter (BLM) protests exposed a critical theoretical tension in political communication: does public opinion simply reflect top-down elite cues, or does the digital sphere empower a bottom-up affective disruption? This study interrogates the causal directionality and affective dynamics between U.S. Congressional discourse and the public during this critical juncture.

Analyzing a comprehensive dataset of over 200,000 tweets, this study integrates advanced Natural Language Processing with rigorous causal inference. Instead of generic sentiment analysis, I employ zero-shot classification to map fine-grained ideological stances and fine-tuned BERT models to quantify toxicity and moral outrage at scale. To determine causality beyond mere correlation, I utilize Interrupted Time Series (ITS) analysis to measure the immediate structural breaks in discourse intensity caused by the George Floyd event. Furthermore, Vector Autoregression (VAR) and Granger Causality tests are applied to empirically determine the temporal precedence of elite versus public sentiment series, testing whether elites lead or follow their base.

Findings reveal a distinct phenomenon of "asymmetric radicalization." While Democratic elites and their public constituents exhibit a synchronized, policy-focused alignment characterized by reciprocal influence, Republican discourse reveals a significant decoupling driven by bottom-up dynamics. Granger causality tests indicate that high-arousal, toxic public sentiment frequently preempts Republican elite messaging by a significant temporal lag, suggesting elites are reacting to, rather than leading, their base. Furthermore, ITS analysis demonstrates a divergence in shock resilience: while Democratic affective intensity stabilized post-event, right-wing public discourse sustained elevated toxicity levels that outpaced elite counter-framing. This suggests that for racial justice issues, social media functions less as a mirror of elite opinion and more as an "affective amplifier" that disproportionately drives right-wing radicalization from the bottom up.

Author

• Sylvia Dou, University of Chicago