How social media users adopt the toxic behaviors of ingroup and outgroup accounts

While the spread of toxicity on social media has received ample attention, studies offer conflicting expectations and mixed evidence about its contagious nature. This study advances understanding of how toxicity becomes contagious by distinguishing between exposure to toxicity by ingroup versus outgroup members and separating toxicity into impolite style and intolerant substance. We focus on Israel during 2023, a period marked by intense political polarization. Using Twitter panel data from original and replication datasets, we analyze ∼1M tweets from 12,481 users and ∼6M tweets from the 713,231 accounts they follow. We find that exposure to toxic behavior by ingroup members is the primary driver of contagious toxicity, compared to smaller, less consistent associations with outgroup toxicity. Moreover, seemingly less harmful forms of toxicity (impoliteness) by the ingroup are not only associated with increased users’ impoliteness but also with increased intolerance toward political groups—which may carry troubling implications for democracies.