🤖 AI Summary
This study investigates the temporal evolution of political out-group hostility on Twitter and Reddit from 2010 to 2023, examining cross-platform and cross-group heterogeneity. Leveraging 67 million tweets and 30 million comments, we develop a joint sentiment–stance analytical framework grounded in pre-trained language models, integrated with user clustering, community-level discourse tracking, and large-scale stratified sampling. Our work delivers the first systematic, longitudinal, multi-group, and cross-platform characterization of out-group hostility. Key findings include: (1) aggregate hostility exhibits sustained growth, with right-wing politicians showing the steepest increase—surpassing left-wing counterparts in recent years; (2) a small set of highly active communities (e.g., r/TheDonald) disproportionately drives polarized expression, and their platform-level bans substantially reconfigure discursive landscapes; (3) significant issue–stance interaction effects emerge (e.g., immigration intensifies right-leaning hostility; healthcare policy amplifies left-leaning hostility). Results demonstrate that polarization spreads non-uniformly, with a minority of users generating the majority of extreme expressions.
📝 Abstract
Using language models, we analyze a sample of 67 million tweets and 30 million Reddit comments referencing a set of 215 political entities from 2010-2023 from partisan users, journalists, and politicians. Our analysis indicates outgroup animosity has increased consistently in our sample, with newer cohorts of users expressing higher levels of animosity than previous ones. Moreover, a small fraction of users are responsible for a disproportionate share of this negative content. We observe systematic differences in topic-level outgroup affect across political orientations: right-leaning users are twice as likely to exhibit outgroup animosity when discussing immigration, while left-leaning users show heightened outgroup animosity when discussing healthcare. On Twitter, U.S. politicians on the left exhibit more outgroup animosity than partisan users in our sample, but in the past four years, politicians on the right have experienced the sharpest rise in outgroup animosity, surpassing journalists, media, and partisan users. On Reddit, a small number of communities account for a large share of polarizing rhetoric, with the rise and eventual ban of r/TheDonald significantly shaping polarizing discourse on the right.
