Trust is one of the cornerstones of human society. One of the evolutionary pressure mechanisms that may have led to its emergence is the presence of incentives for trustworthy behavior. However, this type of reward has received relatively little attention in the context of spatial trust games, which are often used to build models in evolutionary game theory. To fill this gap, we introduce an inter-role reward mechanism in the spatial trust game, so that an investing trustor can choose to pay an extra cost to reward a trustworthy trustee. With extensive numerical simulations, we find that this type of reward does not always promote trust. Rather, while moderate rewards break the dominance of mistrust, thereby favoring investment, excessive rewards eventually stimulate a nonreturn strategy, ultimately suppressing the evolution of trust. Additionally, lower reward costs do not necessarily promote trust. Instead, more costly, but not excessive, rewards enhance the advantage of the original investment, consolidating the clusters of rewarders and improving trust. Our model thus provides evidence about the counterintuitive nature of the relationship between trust and rewards in a complex society.

翻译：信任是人类社会的基石之一。可能导致其出现的进化压力机制之一是对可信赖行为的激励。然而，在空间信任博弈（常用于构建进化博弈论模型）的背景下，此类奖励受到的关注相对较少。为填补这一空白，我们在空间信任博弈中引入了一种跨角色奖励机制，使得投资的信任方可以选择支付额外成本来奖励可信赖的受托方。通过大量数值模拟，我们发现此类奖励并不总能促进信任。相反，适度的奖励虽能打破不信任的主导地位从而有利于投资，但过度的奖励最终会刺激不回报策略，最终抑制信任的演化。此外，较低的奖励成本并不必然促进信任。相反，成本较高但不过度的奖励能增强原始投资的优势，巩固奖励者集群并提升信任。因此，我们的模型为复杂社会中信任与奖励之间反直觉的关系提供了证据。