Exploring the Impact of Trolls on Activity Dynamics in Real-World Collaboration Networks

When new users join social networking websites, they often form collaboration ties with existing users, which in turn may result in some level of activity on the site. However, for various reasons, new users often fail to create such ties and their contributions to the system's overall activity remain insignificant. For example, on Question and Answering portals, such as the StackExchange network, users collaborate to find the best answers for a given set of questions. However, the intentions of new users are highly diverse. While the contributions of most users positively impact the evolution of a community, other participants might just try to steer discussions off-topic or purposely generate discord. To better understand such malicious behavior, it is important to model and quantify the impact of such users on the overall activity in collaboration networks. In this paper we simulate and investigate the influence of trolls-users who intentionally contribute detrimental content-on the total activity of several different StackExchange instances, Semantic MediaWikis and Subreddits. The contributions of this paper are three-fold. First, we simulate activity dynamics in the context of trolls in online collaboration networks. Second, we analyze and quantify the impact of trolls on the levels of activity in these networks. Third, we discuss our results and put them into a real-world context.