This paper examines how gifting spreads among viewers on Twitch, one of the largest live streaming platforms worldwide. Twitch users can give gift subscriptions to other viewers in the chat room, with the majority of gifters opting for community gifting, which is gifting to randomly selected viewers. We identify the random nature of gift-receiving in our data as a natural experiment setting. We investigate whether gift recipients pay it forward, considering various gift types that may either promote or deter the spread of gifting. Our findings reveal that Twitch viewers who receive gift subscriptions are generally more likely to pay it forward than non-recipients, and the positive impact of gift-receiving becomes stronger when the recipient is the sole beneficiary of the giver's gifting behavior. However, we found that gifts from frequent gifters discourage recipients from paying it forward, and gifts from anonymous gifters do not influence the likelihood of viewers becoming future gifters. This research contributes to the existing literature on the spread of online prosocial behavior by providing robust evidence and suggests practical strategies for promoting online gifting.

翻译：本文研究了礼物在全球最大的直播平台之一Twitch上如何在观众间传播。Twitch用户可以在聊天室向其他观众赠送礼物订阅，其中大多数送礼者选择社区礼物——即向随机选择的观众赠送礼物。我们在数据中识别出礼物接收的随机性，这构成了一种自然实验环境。我们考察了礼物接收者是否会继续传递礼物，并考虑了可能促进或抑制礼物传播的不同礼物类型。研究发现，收到礼物订阅的Twitch观众通常比未接收者更可能继续传递礼物，且当接收者是送礼者行为的唯一受益者时，礼物接收的积极影响更为显著。然而，我们发现来自频繁送礼者的礼物会降低接收者继续传递的可能性，而匿名送礼者的礼物则不影响观众成为未来送礼者的概率。本研究通过提供有力证据，丰富了现有关于网络亲社会行为传播的文献，并为促进网络礼物赠送提出了实用策略。