ABSTRACT
Current research on the circulation of disinformation on social media often describes a phenomenon in which communication breaks down into entrenched debates that make participants drift into more extreme positions and attitudes. This phenomenon has been called the echo chamber effect of social media. However, the echo chambers concept remains fragmented in the academic literature, as it blurs at least three distinct phenomena: (1) selective exposure, (2) epistemic isolation, and (3) structures of strategic discrediting. Selective exposure refers to how digital infrastructures filter out the information flow of news media sources. Epistemic isolation is a process in which groups omit relevant knowledge sources. Finally, structures of strategic discrediting are designed to create trust barriers with perceived opponents and critics. This chapter explores the distinctions in the context of social media and offers two examples of social media echo chambers: the flat Earth conspiracy theory and the manosphere. It concludes by presenting avenues for future research that reconcile the three theoretical interpretations.
