The Effect of Agenda-Setting on Occurrence of Echo Chamber on Social Media

Echo chamber refers to a state in which individuals with similar preferences on social media construct closednetworks and consume similar information reflectively. This is one of the causes to prevalent fake news and conspiracyon social media. Previous research has shown that echo chamber is prevented in communication where there aremultiple topics. However, even though communication across multiple topics is common in daily social media use,echo chamber is still occurring on various topics. In this paper, we suggest the presence of agenda-setting as a potentialbackground factor for occurrence of echo chamber from communication on multiple topics. Agenda-setting is theconcept that topics frequently present to users are regarded as significant agendas. In this study, we experimented withmulti-agent simulations to investigate the communication among agents who assess the significance of specific topicsbased on the frequency of encountering them. Our result shows that if a specific topic is recognized as significant bymany users, users construct closed networks as echo chamber on the opinion of significant topic. We also conductedanother experiment to verify the effect of agenda setting by mass media coverage. In this experiment, a specific topiccame to be perceived as significant by many users, but echo chambers did not occur regarding significant topic.