Social signals as design interventions for enhancing citizen science contributions^*

Despite the scientific potential and increasing popularity of web-based citizen science, low contribution from volunteers is often a major hurdle. Studies have shown that individual behavior could be altered through targeted design interventions, but little is known about the specific factors that modulate volunteers’ contributions. A particularly elusive question entails the role of social feedback, in the form of targeted notifications about the contribution of other volunteers. Based on social comparison theory, we hypothesized that (1) volunteers increase contribution when presented with information about a high-performing peer or group, and (2) volunteers conform more strongly to a group rather than to a single peer. To test whether volunteers’ contributions change due to the exposure to the contribution of a peer or group norm, we systematically varied the information presented to participants in an environmental monitoring citizen science project. Volunteers increased their contributions when they were presented with the contribution of a high-performing peer and norm, but they were not influenced by a low-performing peer or norm. Further, we found that volunteers were more likely to match the contributions of a group than that of a peer. However, when volunteers were simultaneously exposed to information about a peer and a group, the effect depended on the respective performance of the peer and group. A theoretical model was developed to explain volunteers’ response and dissect the specific role of social comparison. Our findings offer the possibility of increasing volunteers’ contributions through design interventions.