Quantifying opinion homophily in online social networks from a bounded confidence perspective
Homophily is pervasive in online social media. While many empirical studies have relied on external sociodemographic traits to investigate it, significantly less is known about homophily at the cognitive level, that is, at the level of shared opinions or values. For such “value homophily”, we study interval-based patterns of opinion homophily from a bounded confidence perspective. We consider three heterogeneous datasets from Reddit and Twitter covering polarizing issues, with user opinions quantified via sentiment analysis and fact-checking, and analyze the interaction networks formed by weaker (reply-based) and stronger (follow-based) social ties. Our findings show that users’ interaction neighborhoods are significantly more concentrated in opinion space than expected by chance, with tie strength and issue polarization further amplifying this effect. Moreover, users often exhibit asymmetric tolerance ranges, with asymmetry typically directed toward locally mainstream positions rather than more radical or opposing ones. These findings support a bounded confidence interpretation of value homophily and provide a basis for future studies of exposure and polarization. Homophily in online social media is often examined through external traits, but cognitive-level homophily, based on shared opinions or values, remains underexplored. Here, the authors analyze opinion homophily using opinion estimates based on users’ posts and shared links on Reddit and Twitter, revealing concentrated interaction neighborhoods and asymmetric tolerance, highlighting implications for understanding exposure and polarization dynamics.