We conducted a field experiment in the natural setting of blood donations to test how oxytocin relates to empathy and …

-month large-scale field experiment and a fifteen-month follow-up period, involving more than 10,000 previous donors. We examine … offer of a lottery ticket, on average, increases the probability to donate blood during the experiment by 5.6 percentage … reduction in donations is observed after the experiment. …

's contacts. However, results from a field experiment where broadcasting of the initial pledges was randomized suggest that the … observational findings were likely due to homophily rather than genuine social contagion effects. The experiment also shows that … (30 out of 6.4 million users reached) were made. Finally, an online survey experiment showed that both the presence of an …