Zajkowski Wojciech, Badman Ryan P, Haruno Masahiko, Akaishi Rei
Social Value Decision-Making Collaboration Unit, RIKEN Centre for Brain Science BTCC TOYOTA Collaboration Center, Wako, Saitama, 351-0198, Japan.
Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, MD, USA.
Commun Psychol. 2024 Dec 23;2(1):127. doi: 10.1038/s44271-024-00177-3.
How do group size changes influence cooperation within groups? To examine this question, we performed a dynamic, network-based prisoner's dilemma experiment with fMRI. Across 83 human participants, we observed increased cooperation as group size increased. However, our computational modeling analysis of behavior and fMRI revealed that groups size itself did not increase cooperation. Rather, interaction between (1) participants' stable prosocial tendencies, and (2) dynamic reciprocal strategy weighed by memory confidence, underlies the group size-modulated increase in cooperation because the balance between them shifts towards the prosocial tendency with higher memory demands in larger groups. We found that memory confidence was encoded in fusiform gyrus and precuneus, whereas its integration with prosocial tendencies was reflected in the left DLPFC and dACC. Therefore, interaction between recall uncertainty during reciprocal interaction (i.e., forgetting) and one's individual prosocial preference is a core pillar of emergent cooperation in more naturalistic and dynamic group formation.
群体规模的变化如何影响群体内部的合作？为了研究这个问题，我们使用功能磁共振成像（fMRI）进行了一项基于网络的动态囚徒困境实验。在83名人类参与者中，我们观察到随着群体规模的增加，合作也有所增加。然而，我们对行为和功能磁共振成像的计算建模分析表明，群体规模本身并不会增加合作。相反，（1）参与者稳定的亲社会倾向与（2）由记忆信心加权的动态互惠策略之间的相互作用，是群体规模调节合作增加的基础，因为在较大群体中，随着记忆需求的增加，它们之间的平衡向亲社会倾向倾斜。我们发现，记忆信心在梭状回和楔前叶中编码，而其与亲社会倾向的整合则反映在左背外侧前额叶皮层（DLPFC）和背前扣带回（dACC）中。因此，在互惠互动过程中的回忆不确定性（即遗忘）与个人亲社会偏好之间的相互作用，是在更自然和动态的群体形成中出现合作的核心支柱。
