Key Research Interests
Intergroup Cooperation
People are generally more cooperative towards others in their own group (in-group members) compared to those outside of the group (out-group members). This tendency, in-group favoritism, has been observed in various cultures and contexts and I am interested in understanding why people favor in-group members over out-group members, considering factors such as social identification (Imada et al., 2025 in JDM; Imada et al., 2024 in CRSP) and indirect reciprocity. Specifically, I have extensively worked on sophisticating the group-bounded indirect reciprocity perspective (Imada et al., 2024 in GPIR; Imada et al., 2024 in JESP) and and better understanding the role of group membership in guiding cooperation (Imada et al., 2023).
My interests extend to intergenerational cooperation and sustainable behaviour (Imada et al., under review).
Intergroup Aggression
Human history is rife with intergroup conflicts and wars. While it is tempting to assume that ingroup cooperation and intergroup aggression go hand in hand, existing experimental evidence suggests they are rather distinct (Imada & Mifune, 2024). I examine the minimal condition under which out-group aggression emerges and psychological underpinnings of intergroup aggression and conflicts.
Power and Hierarchy
Power asymmetries and hierarchies are ubiquitous in our society. I examine how power shapes human social behaviors, especially cooperation. I address several questions related to the functions and influences of power; How do people cooperate with in-group members and out-group members when their group involves a power hierarchy? How does having vs. lacking power influence cooperation? Relevant papers include Imada et al. (2023) and Kusano and Imada under review.
Gossip
People spend a lot of time in gossiping, conversations about absent others. Gossip functions as a means to transmit reputational information about others and it helps sustain cooperation in our society. What do people gossip about? Why do people gossip about others? How do people behave when they can be gossiped about? How does gossip play out across group boundaries? Relevant publications include Imada et al., 2022, Imada et al. (2024), and Imada et al. (2021).
Post-Disaster Cooperation
Natural disasters devastate our lives in diverse ways, posing psychological and economical challenges. I am interested in understanding how the affected try to recover from disasters and re-build resources, and I seek ways to facilitate post-disaster reconstruction and cooperation.
Open Science and Science Reform
I embrace the value of open and reproducible science, and I am motivated to contribute to scientific reform in psychological science. I make my research outputs as open and reproducible as possible and I am also interested in replicating / extending prior work. I have worked on and published several registered reports (e.g., Imada et al., 2023; Imada et al., 2022) as well as replication & extension projects (Horsham et al., 2025; Imada et al. 2021).