Multilevel emotion transfer on YouTube: Disentangling the effects of emotional contagion and homophily on video audiences

Why do connected users in online social networks express similar emotions? Past approaches have suggested situational emotion transfers (i.e., contagion) and the phenomenon that emotionally similar users flock together (i.e., homophily). We analyze these mechanisms in unison by exploiting the hierarchical structure of YouTube through multilevel analyses, disaggregating the video- and channel-level effects of YouTuber emotions on audience comments. Dictionary analyses using the National Research Council emotion lexica were used to measure the emotions expressed in videos and user comments from 2,083 YouTube vlogs selected from 110 vloggers. We find that video- and channel-level emotions independently influence audience emotions, providing evidence for both contagion and homophily effects. Random slope models suggest that contagion strength varies between YouTube channels for some emotions. However, neither average channel-level emotions nor number of subscribers significantly moderate the strength of contagion effects. The present study highlights that multiple, independent mechanisms shape emotions in online social networks.