Exploring the effect of social distance on altruism and trust in umbilical cord blood donors

Allogeneic umbilical cord blood (UCB) donation is a prosocial behavior directed to strangers at some cost for the donor. Although the promotion of such behavior is an important goal of many countries’ health systems, little is known regarding the motivations beyond it. Here, we explored how altruism and trust were modulated by social distance in a sample of newmothers (N=168) who might or not have donated the UCB. Participants played hypothetical Dictator and Trust games with others that could be socially close (e.g. parents) or distant (e.g. strangers) from them. They donated more money to parents and siblings compared to cousins, friends and strangers and they trusted more parents, siblings and friends than cousins and strangers. Interestingly, the lower was the impact of social distance on altruism (i.e. higher generosity towards socially distant others) the higher was the intention and the actual probability of UCB donation. A mediation analysis showed that the relationship between social distance on altruism and UCB donation was mediated by objective intention to donate (i.e. having followed all the procedures needed). These findings show that other-oriented motivations towards distant others might have important practical implication for individualizing the targets of interventions aiming at promoting UCB donation.