Abstract
In this study, we conduct a dictator game experiment with the COVID-19 vaccinated and unvaccinated people in Japan, and ascertain allocation tendencies between two anonymous individuals, between two vaccinated individuals or two unvaccinated individuals, and between a vaccinated individual and an unvaccinated individual. By so doing, we assess “ingroup bias,” “outgroup bias,” and “ingroup-favoritism” of vaccinated and unvaccinated people, respectively. Here, ingroup bias is defined as the difference between the money amounts allocated to an individual of the same group as the allocator and to an anonymous individual in the dictator game experiment. Outgroup bias is defined as the difference between the money amounts allocated to an individual of a different group from the allocator’s and to an anonymous one, and ingroup-favoritism is defined as the difference between the money amounts allocated to an individual of the same group and to an individual of the different group.
Specifically, we employ an experimental design that allows for both between- and within-individual comparisons to conduct the following analyses. First, in the between-analysis, we test the existence of ingroup bias, outgroup bias, and ingroup-favoritism in each group of vaccinated and unvaccinated individuals. In addition, we examine how these biases differ between vaccinated and unvaccinated individuals. We further investigate how the biases change between when the vaccination status of the allocator is not informed to the recipient and when it is informed to them.
Next, in the within-analysis, we test whether individuals' ingroup bias, outgroups bias, and ingroup favoritism are associated with their real-world attitudes and behaviors. In both the vaccinated and unvaccinated group, we examine the association between their biases and attitudes toward the COVID-19-related policies. In the vaccinated group, we also examine the association between their biases and the timing of COVID-19 vaccination.
To stably manage a society under a pandemic, it is crucial to build cooperative relationships between vaccinated and unvaccinated people. This study can contribute to the smooth construction of such cooperative relationships.