Abstract
The provision of activities with external benefits that rely on voluntary contributions may often fall below societal needs. In this article, we focus on such contributions to a citizen science project (the World Community Grid) in which members of the general public are asked to offer unused computer power to advance cutting-edge scientific research. We investigate the role played by symbolic awards in stimulating existing contributors to recruit new contributors for this project. The recruitment campaign we study introduces badges for referrals (visible on each user’s public profile page) varying, across randomized treatment groups, the threshold of successful referrals needed to receive these badges. We find that these symbolic incentives are effective in boosting referrals, and more so when the minimum threshold for achieving symbolic awards is higher. However, the overall effect of the incentives is quite modest, highlighting the challenges of running referral campaigns for the recruitment of volunteers.