Lost in the Crowd: How Group Size and Content Moderation Shape User Engagement in Live Streaming

Live streaming platforms such as Twitch and YouTube Live now play a central role in digital engagement, offering real-time interaction that grows increasingly complex with larger audiences. Our study leverages the exogenous viewer influx from Twitch’s Raid function to examine how increases in group size affect user engagement. Analyzing chat histories from more than 7,000 playbacks using a difference-in-differences approach, we find that although attracting more viewers, larger group sizes also lead to reduced engagement among existing participants. This decline is linked to increased topic incoherence and heightened emotional volatility—or comment polarity—in live chats. Importantly, our results highlight that targeted moderation strategies can mitigate these negative effects. Bot moderators are particularly effective in maintaining coherence during large-scale raids, whereas human moderators better manage emotional surges when the incoming group is smaller. These findings reveal a congestion effect in synchronous digital environments and offer clear practice- and policy-oriented implications: Online synchronous platforms should consider the scalability of viewers and commenters and use flexible moderation strategies to sustain user engagement and foster healthier, more constructive real-time interactions.