Partisan Perceptual Bias and the Information Environment

Perceptual bias occurs when beliefs deviate from reality. Democrats and Republicans are thought to be especially susceptible to this type of biased-information processing. And yet we know little about the pervasiveness of perceptual bias outside the domain of “performance issues” (e.g., unemployment, inflation) or how individual-level partisan motivation interacts with the information environment. We investigate these issues in two studies that examine perceptual bias on a wide range of political topics spanning two decades. Using survey data as well as an experiment with diverse subjects, we demonstrate that people perceive the world in a manner consistent with their political views. The result is a selective pattern of learning in which partisans have higher levels of knowledge for facts that confirm their world view and lower levels of knowledge for facts that challenge them. This basic relationship is exaggerated on topics receiving high levels of media coverage.