Seminars

Abstract: The issue of receiving vaccines or not divides people: however, both the vaccinated and unvaccinated people need to live together in the same society. This study conducted financially incentivized dictator games with around 1,600 COVID-19 vaccinated or unvaccinated people residing throughout Japan and evaluate their cooperative or hostile attitudes toward each other by using ingroup favoritism, which is the difference in the allocated amounts between to ingroup pairs with the same vaccination status and to outgroup pairs with a different status. Our study’s uniqueness is conducting the first experiment in January-February 2022 and the follow-up experiments in December 2022 and June 2023 to examine how the attitudes change toward the post-pandemic era. The first experiment suggests that the COVID-19 vaccinated people behave more discriminately toward outgroup members, when compared to the unvaccinated people. The vaccinated people show strong ingroup favoritism, which is shaped mainly by their outgroup bias of decreasing the allocation amount to an unvaccinated pair, their outgroup. In contrast, the unvaccinated people do not exhibit such ingroup favoritism. Their outgroup bias is found in the rather opposite direction of the hypothesis, and they tend to increase the allocation amount to a vaccinated pair, their outgroup. This tendency is found in particular from the unvaccinated people who selected as their non-vaccination reason “I would like to get vaccinated if I could, but I cannot for health or other reasons.” The two follow-up experiments find that the vaccinators’ ingroup favoritism is persistent over the medium term, while the non-vaccinators’ favorable attitude toward their outgroup pair is temporary, and they gradually exhibit so-called ingroup favoritism.