How does segregation along ethnic boundaries emerge in social networks? Human evolution resulted in highly social beings, capable of prosociality, mindreading, and self-control, which are important aspects of the “social brain.” Our neurophysiologically “wired” social cognition implies different cognitive goal frames. In line with recent developments in behavioral theory, the present study defines network ties as episodes of social exchange. This dynamic definition can account for shifts in goal frames during an exchange episode: whereas deliberate choice and hedonic or gain goals drive the initiation of a tie, given the opportunity structure, the normative goal frame activates a strong dynamic effect of reciprocity, which limits actors’ choice set and appears as “self-organization” at the network level. Longitudinal analyses of 18 birthday party networks comprising 501 students support the definition of network ties as exchange episodes, as well as the relevance of humans’ inherent tendency to reciprocate. However, reciprocation is much stronger in dyads of the same ethnicity than in dyads of different ethnicities. Network segregation along ethnic boundaries results from deliberate decisions during the initiation of an episode, but also from different commitments to reciprocity during the ongoing exchange process, depending on intra or interethnic dyadic constellations.

社交网络中的种族隔离是如何出现的？人类进化导致高度社会化的存在，能够亲社会、读心术和自我控制，这些都是“社会大脑”的重要方面。我们的神经生理学“连线”社会认知意味着不同的认知目标框架。根据行为理论的最新发展，本研究将网络关系定义为社会交流的片段。这种动态定义可以解释交换过程中目标框架的变化：而故意选择和享乐或获得目标推动了平局的开始，鉴于机会结构，规范目标框架激活了强烈的动态效应互惠，它限制了参与者的选择集，并在网络层面表现为“自组织”。对由 501 名学生组成的 18 个生日聚会网络的纵向分析支持将网络关系定义为交换事件，以及人类固有的回报倾向的相关性。然而，在同种族的二元组中，互惠比在不同种族的二元组中强得多。沿种族边界的网络隔离源于一个事件开始期间的深思熟虑的决定，但也源于正在进行的交流过程中对互惠的不同承诺，这取决于内部或种族间的二元星座。