Biased news sharing and partisan polarization on social media

Abstract In the ever-connected digital landscape, news dissemination on social media platforms serves as a vital source of information for the public. However, this flow of information is far from unbiased. It is deeply influenced by the political inclinations of the users who share news as well as the inherent biases present in the news outlets themselves. These biases in news consumption play a significant role in the creation of echo chambers and the reinforcement of beliefs. This phenomenon, in turn, influences the voting intentions of the population during critical electoral periods. In this study, we use a metric called ''Sentiment Bias”, a tool designed to classify news outlets according to their biases. We explore the impact of this metric on various levels, ranging from news outlets to individual user biases. Our metric, while simple, unveils a well-known trend: users prefer news aligning with their political beliefs. Its power lies in extending this insight to specific topics. Users consistently share articles related to subjects that echo their favored candidates, illuminating a deeper layer of political alignment in online discourse.