Published in Strategic Polarization through Social Media (book), 2022.
Public debate on social media platforms like Twitter is increasingly shaped by political polarization and echo chambers. In this project, commissioned by Mexico’s National Electoral Institute (INE), we studied how Twitter contributed to polarization during Mexico City’s 2021 electoral process.
Using network science methods, we constructed retweet networks to map the structure of political conversation on Twitter over multiple semesters. We identified distinct ideological blocs — ranging from strong government supporters to opposition clusters — and tracked how interactions between and within these groups evolved over time. Our analysis reveals that Twitter debate was heavily marked by Mexican presidentialism, with content and discussion gravitating around the executive branch.
Key findings include: (1) echo chambers are prevalent, with users predominantly retweeting content aligned with their own political bloc; (2) the onset of electoral campaigns did not increase polarization beyond levels already observed in prior months; and (3) cross-bloc interactions — conversations between opposing groups — decreased over time, suggesting a deepening of ideological silos. We also conducted experimental analyses to examine how anonymity and bot-like behavior influence polarization dynamics on the platform.
These results provide an empirical diagnosis of how social media structures political discourse and highlight risks for democratic deliberation in digital spaces.