PhD thesis defence by Joris Frese
This dissertation contributes to the study of causal effects of elite behavior on public opinion. Particularly, I focus on political communication in light of scandals and crises, investigating the conditions under which, and the mechanisms through which, political elites can influence the public. Furthermore, I present several methodological interventions to improve the use of the Unexpected Event during Survey Design (UESD), a widely adopted method for the study of opinion changes in response to information shocks.
In the first paper, I study reactions to refugee movements triggered by the Taliban takeover of Afghanistan. I show that politicians and journalists alike framed these refugees as vulnerable and assimilable, appealing to both altruistic and egocentric motives of the public. These deservingness frames were effective at reducing xenophobia across Europe, particularly when they were employed by ideologically aligned politicians.
In the second paper, I expand the study of heterogeneous treatment effects by messenger-recipient relation. I theorize politicians as opinion leaders and show how voters align their policy preferences with politicians they perceive as having high valence. Negative valence-shocks undermine or even reverse this policy alignment.
The third paper focuses on migration frames that only address altruistic, but not egocentric motives (studying Mediterranean shipwrecks), and documents their inability to make recipients more empathetic toward migrants. I also present a framework to improve the external validity of UESDs exploiting recurring events such as shipwrecks or terrorist attacks for causal identification.
The fourth paper demonstrates an influx of false-positive results in UESD studies and introduces a method and software to account for this error inflation. Lastly, two supplemental papers discuss the robustness and validity of UESD research based on a review (meta-analysis) of 126 (64) published studies. Together, these chapters provide novel insights into communication effects and best-practices for their study.
Joris Frese is a PhD candidate at the EUI Department of Political and Social Sciences under the supervision of Simon Hix. He studies how political elites can influence public opinion and is interested in quantitative methodology and metascience. In September 2026, he will join Nuffield College at the University of Oxford as a Postdoctoral Prize Research Fellow in Politics.
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