Zero is hero: Round number effects on knowledge-sharing platforms

With the inherent public goods problem embedded in knowledge-sharing platforms, various incentive mechanisms have been implemented, most of which are in the form of gamified elements. Among those motivating elements, reputation points are the most direct feedback about individuals' contribution effort, which use numerical units indicating progress. Although some research has found that points can incentivize users to contribute, empirical evidence regarding the influential patterns of such numerical units remains limited. Drawing on numerical cognition literature that an individual's evaluation and judgments may be influenced by certain numerical cues, we particularly focus on the round number bias on knowledge-sharing platforms. Several hypotheses regarding users' behavioral changes when their accumulated points approach round numbers have been proposed, including their contribution level, contribution quality, and writing style. By analyzing data collected from StackOverflow.com, we find that users perceive round numbers as category boundaries or endpoints and crossing such boundaries can motivate aspirational behaviors. Concretely, users significantly increase their post frequency and length, and write answers with more function words and second-person pronouns. Meanwhile, their posts will be more likely to be accepted as the best answers and gain more votes. We also explore the moderating effects of advanced explicit incentives and numbers' magnitude. Theoretically, our research contributes to a body of literature on knowledge-sharing platform incentive mechanisms to motivate users' contributions and sheds light on the utilization of numerical cues to guide individuals' behaviors in user generated-content (UGC) provision context.