Speaker: Valeria Burdea (LMU Munich)

Title: Partisan Biases in Source Credibility Beliefs

When: Monday, 3 November 2025, 11:30 am – 13:00 pm

Where: Oskar-Morgenstern-Platz, lecture hall 7 (1st floor) (map)

Abstract:

Political polarization over basic facts poses a serious challenge to the functioning of democracies. Yet distinguishing between competing explanations for fact polarization through evidence of learning (first-order beliefs) is hindered by observational equivalence. To address this limitation, we examine source credibility (second-order) beliefs - perceptions of the accuracy of others’ factual knowledge. Our findings reveal strong evidence that in-group partisan bias is a key mechanism linking first-order rational learning to fact polarization. In-group partisans are consistently perceived as having more accurate knowledge than out-group partisans. This partisan gap is primarily driven by political affect - feelings toward members of each party - rather than party-specific knowledge, implying a hybrid model of first-order rational learning with second-order motivated reasoning. These results have direct implications for media, institutions, and policymakers seeking to mitigate bias and reduce polarization.