Perceptions of Political Bias and the Polarization Cycle

Citizens rely in large part on the testimony of others to learn about politics, but political information sources make competing claims, and are often unreliable due to their biases. Citizens’ beliefs about the relative bias of competing sources may therefore influence how their beliefs change over time, potentially causing belief polarization between citizens who disagree about which sources are more biased. Across a 40-month, 7-wave study (ns = 800-1000) of British citizens with quota-representative samples, we find that partisans typically believe their opponents to be more biased than their own group with a large effect size (d = 1.01), and beliefs about the relative bias of supporters of Labour and Conservative partisans predict the size and direction of changes in political belief over time. We also find the reciprocal – political beliefs predict changes in perceptions of who is more biased, suggesting the potential for a ‘polarization cycle’ whereby belief polarization and bias perception polarization reinforce each other in a positive feedback loop. Bias perceptions are also predictive of changes in affective polarization. These relationships are robust to controlling for potential confounders including partisanship and ideological identity.