Social media platforms have witnessed a substantial increase in social bot activity, significantly affecting online discourse. Our study explores the dynamic nature of bot engagement related to Extinction Rebellion climate change protests from 18 November 2019 to 10 December 2019. We find that bots exert a greater influence on human behavior than vice versa during heated online periods. To assess the causal impact of human-bot communication, we compared communication histories between human users who directly interacted with bots and matched human users who did not. Our findings demonstrate a consistent negative impact of bot interactions on subsequent human sentiment, with exposed users displaying significantly more negative sentiment than their counterparts. Furthermore, the nature of bot interaction influences human tweeting activity and the sentiment towards protests. Political astroturfing bots increase activity, whereas other bots decrease it. Sentiment changes towards protests depend on the user's original support level, indicating targeted manipulation. However, bot interactions do not change activists' engagement towards protests. Despite the seemingly minor impact of individual bot encounters, the cumulative effect is profound due to the large volume of bot communication. Our findings underscore the importance of unrestricted access to social media data for studying the prevalence and influence of social bots, as with new technological advancements distinguishing between bots and humans becomes nearly impossible.

翻译：社交媒体平台上社交机器人活动显著增加，深刻影响了在线话语生态。本研究探索了2019年11月18日至2019年12月10日期间与"反抗灭绝"气候变化抗议活动相关的机器人参与动态。研究发现，在网络讨论激烈时期，机器人对人类行为的影响远大于人类对机器人的影响。为评估人机通信的因果效应，我们比较了直接与机器人互动的用户和匹配的未互动用户的通信历史。结果表明，机器人互动对人类后续情绪产生持续负面影响，暴露于机器人互动的用户表现出显著更消极的情绪。此外，机器人互动的性质会影响用户的推文发布活动以及对抗议活动的情绪倾向：政治草根运动机器人增加用户活跃度，而其他类型机器人则降低活跃度。对抗议活动情绪的变化取决于用户原本的支持程度，表明存在针对性操纵。但机器人互动并未改变活动家对抗议活动的参与度。尽管单个机器人互动的影响看似微小，但由于机器人通信的巨大体量，其累积效应十分显著。本研究的发现强调了不受限制地访问社交媒体数据对于研究社交机器人普遍性和影响力的重要性——随着新技术的发展，区分机器人与人类已近乎不可能。