Abstract
While costly signals of commitment were proposed to facilitate cooperative assortment in humans, little is known about cognitive processes facilitating the reliability of such commitment signals. Across three studies (total N = 2,223), we test whether this reliability is supported by intuitive processes or by deliberative cost-benefit evaluations. Participants played a public goods game in which they could send variously costly signals of commitment, and the signaling decision was made either under time pressure or delay. Under pressure, signals separated cooperators from selfish players only when signal cost was high. However, these intuitive, high-cost signals did not consistently predict subsequent cooperation. By contrast, when participants had time to deliberate under time delay, cooperators selectively chose the low-cost signal more often than selfish players and contributed more to the common pool. These findings suggest that reliable commitment signaling depends less on intuitive attraction to costly displays and more on deliberative cost-benefit evaluation where cooperators optimize signal cost.