The Bias-and-Expertise Model: A Bayesian Network Model of Political Source Characteristics

Perceptions of source credibility may play a role in major societal challenges like political polarization and the spread of misinformation, as citizens disagree over which sources of political information are credible, and sometimes trust untrustworthy sources. Cognitive scientists have developed Bayesian Network models of how people integrate perceptions of source credibility when learning from information provided by sources, but these models don’t involve the crucial source characteristic in politics: bias. Biased sources make claims that align with a particular political agenda whether or not they are true. We present a novel Bayesian Network model which integrates perceptions of a source’s bias as well as their expertise. We demonstrate the model’s validity for predicting how people will update beliefs and perceptions of bias and expertise in response to testimony across four studies, the fourth being a pre-registered conceptual replication of the first three.