YOKOTA Kunihiro    Department   Hiroshima shudo University  The Faculty of Health Sciences    Position   Professor
Date	2018/07/05
Presentation Theme	Two types of ingroup cooperation, group-based and reciprocity-based psychological mechanisms.
Conference	30th annual meeting of the Human Behavior and Evolution Society
Promoters	The Human Behavior and Evolution Society
Conference Type	International
Presentation Type	Poster
Contribution Type	Collaborative
Venue	Amsterdam, Neherland
Publisher and common publisher	Nakagawa, Y., Yokota, K., & Nakanishi, D.
Details	This study tested the validity of adaptive psychological mechanisms to generate human ingroup cooperation behavior in real social groups. From the evolutionary perspective, two types of the mechanism have been proposed, the group-based mechanism (cooperation due to the belongingness of a same category) and the reciprocity-based mechanism (cooperation triggered by the expectation that other ingroup members will cooperate reciprocally). Although ingroup cooperation stemmed from both types of mechanism have been observed in laboratory experiments, it still remains the questions what factors could prompt each type of mechanism to function and whether ingroup cooperation based on the mechanisms would be observed even in real social groups. We investigated the hypothesis that cost of cooperation would enhance the reciprocal ingroup cooperation in the laboratory experiment, using Prisoner’s Dilemma game that cost of cooperation was required. Those who regarded themselves as a baseball fan participated in it. To manipulate reciprocity between participants and their partner, they informed their and/or their partner’s group belongings (fan of same team or not). The results showed that the reciprocity-based cooperation was found in the possible expected reciprocity situation. The boundary conditions that two types of psychological mechanism underlying human cooperative behavior are discussed.