CMX Lunch Seminar: Heather Zinn Brooks

Influence of media on opinion dynamics in social networks

Many people rely on online social networks as sources for news and information, and the spread of media content with ideologies across the political spectrum both influences online discussions and impacts actions offline. To examine such phenomena, we generalize bounded-confidence models of opinion dynamics on a social network by incorporating media accounts as influencers. We quantify partisanship of content as a continuous parameter on an interval, and we present higher-dimensional generalizations to incorporate content quality and increasingly nuanced political positions. We simulate our model with one and two ideological dimensions, and we use the results of our simulations to quantify the ``entrainment'' of non-media account content to the ideologies of media accounts in networks. We maximize media impact over a social network by tuning the number of media accounts that promote the content and the number of followers of the accounts. Through our numerical computations, we find that the entrainment of the non-media content's ideology to the media ideology depends on structural features of networks such as size, mean number of followers, and the receptiveness of nodes to different opinions. We then introduce content quality --- a key novel contribution of our work --- into our model. We incorporate multiple media sources with ideological biases and qualities that we draw from real media sources and demonstrate that our model can produce distinct communities (``echo chambers") that are polarized in both ideology and quality. Our model provides a step toward understanding content quality in spreading dynamics, with important ramifications for how to mitigate the spread of undesired content and promote the spread of desired content.