Updating politicized beliefs: How motivated reasoning contributes to polarization

This paper examines how the political significance of information can affect subjects’ perceived reliability of that information and their motivated belief updating. In this study, 1,222 subjects were randomly assigned to receive low-reliability, high-reliability, or ambiguous information about neutral and political questions. For each question, subjects were first asked to give a numerical estimate. After receiving new information, subjects had the opportunity to update their previous numerical estimates, and then, they reported their perceived reliability of the information they received. I observed that subjects were more reluctant to update their beliefs for politically significant questions compared to neutral questions. I also found that subjects were more likely to discredit and reject new information when it challenged their preexisting ideology, indicating that one’s rooted political beliefs can distort the belief updating process. In addition, subjects drew different conclusions from ambiguous information depending on their political ideology, illustrating how ambiguity may lead to greater polarization. Finally, I discuss possible explanations for subjects’ biased integration of new information using motivated reasoning and belief-based utility theories. The results of this study contribute to the understanding of why people remain divided on politically charged issues.