In two pre-registered and fully incentivized studies ( N = 501), we investigate prosocial behavior during the COVID-19 pandemic in Germany. Based on a comparison with pre-pandemic data, Study 1 shows that individuals’ general prosociality measured with a (context-independent) Social Value Orientation Slider changed significantly before vs. during the early stage of the pandemic towards increased prosociality. In addition, we identified pandemic-specific context factors for prosocial behavior measured by a series of Dictator games with different recipients. Allocations in the Dictator game increased with the giver's responsibility and the recipients’ vulnerability to the virus. Study 2 replicates and extends this finding in a sample representative for the adult German population in terms of age and gender. We show that, for different actors (self, recipient, politicians), different dimensions of responsibility (responsibility to help, responsibility for the problem cause, and for the solution) are associated with prosocial behavior. Contrary to what could be expected from diffusion of responsibility, prosocial behavior increased not only when individuals themselves felt responsible to help but also when they perceived politicians to be responsible to help. Assigning responsibility for the cause of the COVID-19 crisis to recipients and politicians was associated with a decrease in prosocial behavior. However, responsibility for the solution had no influence. We discuss implications for public policies.

In two comprehensive and fully incentivized studies, we investigate the development of ingroup favoritism as one of two aspects of parochial altruism in repeated social dilemmas. Specifically, we test whether ingroup favoritism is a fixed phenomenon that can be observed from the very beginning and remains stable over time, or whether it develops (increases vs. decreases) during repeated contact. Ingroup favoritism is assessed through cooperation behavior in a repeated continuous prisoner's dilemma where participants sequentially interact with 10 members of the ingroup (own city and university) and subsequently with 10 members of the outgroup (other city and university), or vice versa. In none of the experiments do we observe initial differences in cooperation behavior for interaction partners from the ingroup, as compared to outgroup, and we only observe small differences in expectations regarding the interaction partners' cooperation behavior. After repeated interaction, however, including a change of groups, clear ingroup favoritism can be observed. Instead of being due to gradual and potentially biased updating of expectations, we found that these emerging differences were mainly driven by the change of interaction partners' group membership that occurred after round 10. This indicates that in social dilemma settings ingroup favoritism is to some degree dynamic in that it is enhanced and sometimes only observable if group membership is activated by thinking about both the interaction with the ingroup and the outgroup.

Over the past decade, the world has faced an unprecedented refugee crisis. The large number of incoming refugees represents a challenge for host societies and its citizens triggering reactions from a supportive welcome to brusque rejection and hostile behavior toward refugees. In a pre-registered study, we investigated factors that could promote altruistic behavior in fully incentivized one-shot Dictator Game toward various receiver groups including refugees. We find that host citizens behave more altruistically toward refugees and other receiver groups if they (a) share a local identity with them (i.e., live in the same city), and (b) perceive them to be close (to the self) and warm-hearted. Moreover, citizens that are (c) generally more prosocial and hold a more left-wing political orientation are more willing to give. Unexpectedly, from a theoretical point of view, altruistic giving toward refugees was not influenced in the predicted direction by a shared student identity, competition and perceived income differences (although the latter effect was significant when considering all receiver groups). For shared student identity we even observe a reduction of altruistic behavior, while the opposite effect was predicted. We discuss implications for public policies for successful refugee helping and integration.