Political Polarization in Social Media: Analysis of the 'Twitter Political Field' in Japan

摘要

There is an ongoing debate about whether the Internet is like a public sphereor an echo chamber. Among many forms of social media, Twitter is one of themost crucial online places for political debate. Most of the previous studiesfocus on the formal structure of the Twitter political field, such as itshomophilic tendency, or otherwise limit the analysis to a few topics. In orderto explore whether Twitter functions as an echo chamber in general, however, wehave to investigate not only the structure but also the contents of Twitter'spolitical field. Accordingly, we conducted both large-scale social networkanalysis and natural language processing. We firstly applied a communitydetection method to the reciprocal following network in Twitter and found fivepolitically distinct communities in the field. We further examined dominanttopics discussed therein by employing a topic model in analyzing the content ofthe tweets, and we found that a topic related to xenophobia is circulatedsolely in right-wing communities. To our knowledge, this is the first study toaddress echo chambers in Japanese Twitter political field and to examine theformal structure and the contents of tweets with the combination of large-scalesocial network analysis and natural language processing.