Human decision-making is often swayed by irrecoverable investments even though it should only be based on future—and not past—costs and benefits. Although this sunk cost effect is widely documented and can lead to devastating losses, the underlying psychological mechanisms are unclear. To tease apart possible explanations through a comparative approach, we assessed capuchin and rhesus monkeys’ susceptibility to sunk costs in a psychomotor task. Monkeys needed to track a moving target with a joystick-controlled cursor for variable durations. They could stop at any time, ending the trial without reward. To minimize the work required for a reward, monkeys should have always persisted for at least 1 s, but should have abandoned the trial if that did not yield a reward. Capuchin monkeys and especially rhesus macaques persisted to trial completion even when it was suboptimal, and were more likely to complete the trial the longer they had already tracked the target. These effects were less pronounced, although still present, when the change in expected tracking duration was signalled visually. These results show that sunk cost effects can arise in the absence of human-unique factors and may emerge, in part, because persisting can resolve uncertainty.

人类的决策常常受到无法收回的投资的影响，尽管它应该只基于未来（而不是过去）的成本和收益。尽管这种沉没成本效应已被广泛记录并可能导致毁灭性损失，但其潜在的心理机制尚不清楚。为了通过比较方法梳理可能的解释，我们评估了卷尾猴和恒河猴对精神运动任务中沉没成本的敏感性。猴子需要用操纵杆控制的光标在不同的持续时间内跟踪移动目标。他们可以随时停止，结束审判而没有任何奖励。为了尽量减少获得奖励所需的工作，猴子应该始终坚持至少 1 秒，但如果没有产生奖励，则应该放弃试验。卷尾猴，尤其是恒河猴，即使在效果不佳的情况下也会坚持完成试验，并且跟踪目标的时间越长，完成试验的可能性就越大。当预期跟踪持续时间的变化以视觉方式发出信号时，这些影响虽然仍然存在，但不太明显。这些结果表明，在没有人类独特因素的情况下，沉没成本效应可能会出现，并且可能会出现，部分原因是持续存在可以解决不确定性。