This PhD project consists of four sub-projects that revolve around the central research question: “How do social relations and social interactions shape prosocial behavior in the form of blood and plasma donations?”. Each of the four subprojects illuminates a different aspect of this question and the figure below provides a brief overview. 

Currently, we are evaluating results from the first sub-project (P1), which focuses on individuals’ repeated prosocial behavior: behavior that benefits unknown and unrelated others, is costly to individuals themselves, and nevertheless is repeated over time. Based on the results of experimental studies, social relations are understood as pivotal for sustaining individuals’ repeated prosocial behavior over time. That is because they provide channels through which social contagion can work, which we broadly define as an individual changing their behavior in response to their peers’ behavior. This study examines to what extent and through which mechanisms social contagion contribute to sustaining individuals’ repeated blood donation behavior, an archetypal manifestation of real-world prosocial behavior. We draw on longitudinal survey and register data of the Dutch blood donor population in 2007-2009 and 2012-2013 (N=15 090). By utilizing panel data and an instrumental variable approach we address the potential endogeneity of peers’ donation behavior. Our results show that a one unit increase in the number of donations per peer is associated with a 10% increase in the number of an individual’s blood donations. A mediation analysis, however, does not provide conclusive evidence that normative or informational social influence are mechanisms underlying social contagion. Our findings imply that the maintenance of individuals’ repeated real-world prosocial behavior is facilitated if their peers contribute to a higher degree. For blood banks, this means that social contagion within groups of donors could be used to improve strategies aimed at donor retention.

The preprint will be available soon!