Is there an echo in here? Is the echo damaging? The causes and effects of political homogeneity in online networks

Recently, public debates related to metaphors such as echo chambers and filter bubbles have emphasized how the formation of like-minded spaces can harm democratic systems. In fact, human beings have always tended to surround themselves by those who act and think alike. Still, the extent and the potential effects of this human tendency specifically in online networks are yet to be understood. This chapter summarizes a five-year research program at the intersection of media psychology, communication studies, and social media analytics devoted to understanding the emergence and the consequences of political homogeneity in social media. We present subjective and objective measures of political homogeneity, which psychological factors facilitate its emergence, and how its presence can shape perceptions of public opinion, metacognitions, personal opinions, and expressive actions. Drawing on this evidence, we outline its implications for strengthening and securing democracy in digitized societies.