Abstract

The iterated prisoner’s dilemma (iPD) game is a well established model for testing how people cooperate, yet the neural processes that unfold after its distinct outcomes have been only partly described. Recent theoretical models emphasize the ubiquity of intuitive cooperation, raising questions on both neural and behavioral timelines involved. We studied the outcome/feedback stage of iPD rounds with electroencephalography (EEG) methods. Results showed that neural signals associated to this stage also relate to future choice in an outcome-dependent manner: (i) after zero-gain ‘sucker’s payoffs’ (unreciprocated cooperation), a participant’s decision thereafter relates to changes to the feedback-related negativity (FRN); (ii) after one-sided non-cooperation (participant wins at co-player’s expense), by the P3; (iii) after mutual cooperation, by late frontal delta-band modulations. Critically, faster choices to reciprocate co-player cooperation were predicted, on a single-trial basis, by P3 and frontal delta modulations at the immediately preceding trial. Delta band signaling is considered in relation to homeostatic regulation processing in the literature. The findings relate the early outcome/feedback stage to subsequent decisional processes in the iPD, providing a first neural account of the brief timelines implied in heuristic modes of cooperation.

摘要

迭代的囚徒困境（iPD）游戏是一种用于测试人们如何合作的成熟模型，但仅部分描述了其独特结局后展开的神经过程。最近的理论模型强调了直观合作的普遍性，对涉及的神经和行为时间表提出了疑问。我们用脑电图（EEG）方法研究了iPD循环的结果/反馈阶段。结果表明，与该阶段相关的神经信号也以结果依赖的方式与未来的选择有关：（i）在获得零收益的“吸盘收益”（互惠合作）之后，参与者的决策此后与反馈相关的负相关（FRN）；（ii）在单方面不合作（参与者以共同玩家的费用获胜）之后，由P3负责；（iii）在相互合作之后，通过后期的正面三角带调制。至关重要的是，在紧接之前的试验中，通过P3和额叶三角洲调制预测了在单次试验中往复合作玩家合作的更快选择。在文献中考虑与稳态调节处理有关的δ带信号。这些发现将早期的结果/反馈阶段与iPD中的后续决策过程相关联，从而提供了启发式合作模式所隐含的简短时间表的第一个神经系统解释。