Preferences for efficiency, rather than preferences for morality, drive cooperation in the one-shot Stag-Hunt Game

Recent work highlights that cooperation in the one-shot Prisoner’s dilemma (PD) is primarily driven by moral preferences for doing the right thing, rather than social preferences for equity or efficiency. By contrast, little is known on what motivates cooperation in the Stag-Hunt Game (SHG). Cooperation in the SHG fundamentally differs from cooperation in the PD in that it is not costly, but risky: players have no temptation to deviate from the cooperative outcome, but cooperation only pays off if the other player cooperates. Here, we provide data from a large (N=436), pre-registered, experiment. Contrary to what has been observed for the PD, we find that SHG cooperation is primarily driven by preferences for efficiency, rather than preferences for doing the right thing.

💡 Research Summary

The paper investigates the motivational drivers of cooperation in the one‑shot Stag‑Hunt Game (SHG), a coordination game where cooperation is risk‑dominant but not costly. Building on recent work that identified moral preferences as the primary engine of cooperation in the one‑shot Prisoner’s Dilemma (PD), the authors ask whether the same holds for the SHG or whether other social preferences dominate. They pre‑registered a large‑scale online experiment (N = 436) on Amazon Mechanical Turk, following the methodology of Capraro & Rand (2018). Participants first played a paired SHG with the payoff matrix: (A,A) = 25,25; (A,B) = 25,5; (B,A) = 5,25; (B,B) = 40,40. “A” is the safe, low‑payoff option; “B” is the risky, high‑payoff cooperative option. After the SHG, the same participants were grouped into trios to play a Trade‑Off Game (TOG) in which they acted as dictators choosing between an equitable allocation (13,13,13) and an efficient allocation (13,23,13). The TOG was presented under two framing conditions: an “efficient frame” (the efficient option labeled “be generous” and the equitable option “be ungenerous”) and an “equitable frame” (the equitable option labeled “be fair” and the efficient option “be unfair”). This design allows the authors to disentangle a pure efficiency preference (choosing the efficient allocation regardless of moral wording) from a moral preference (choosing the option that is framed as morally right).

Two competing hypotheses were pre‑registered: (1) the “efficiency preferences hypothesis” predicts a positive correlation between choosing the efficient allocation in the TOG and cooperating in the SHG; (2) the “moral preferences hypothesis” predicts a positive correlation between the positively framed TOG choice (regardless of efficiency) and SHG cooperation. After excluding participants who failed comprehension checks or submitted duplicate responses, the authors conducted logistic regressions with SHG cooperation (1 = cooperate, 0 = safe) as the dependent variable. Independent variables included a dummy for TOG efficient choice, a dummy for TOG framing, and their interaction, with gender, age, and education as controls.

Results show a robust positive effect of the TOG efficient choice on SHG cooperation (b ≈ 0.61, p < 0.05) in both specifications, while the framing dummy and the interaction term are statistically insignificant. A χ² test confirms that the sum of the framing coefficient and its interaction with efficient choice differs from zero, indicating that framing does not drive the observed relationship. Notably, the effect is strongest in the equitable‑frame condition (p < 0.046) and absent in the efficient‑frame condition (p > 0.80). This pattern suggests that participants who select the efficient allocation even when it is negatively framed (“unfair”) possess strong efficiency motives that outweigh moral framing.

The authors interpret these findings as evidence that SHG cooperation is primarily motivated by efficiency preferences rather than moral preferences for “doing the right thing.” This contrasts with the PD literature, where moral preferences dominate. The paper highlights that the structural differences between PD (costly cooperation with temptation to defect) and SHG (risk‑dominant, cost‑free cooperation) likely shift the salient social motive. The experimental design’s strengths include pre‑registration, a sizable sample, and the clever use of the TOG to operationalize distinct preference dimensions. Limitations involve the online setting’s external validity, the simplified monetary stakes, and the cultural specificity of framing effects.

In conclusion, the study provides novel empirical support for the claim that, in coordination games where cooperation is risky but not costly, individuals are driven more by a desire to achieve efficient outcomes than by abstract moral considerations. This insight has practical implications for designing institutions or incentives that aim to foster cooperation: emphasizing efficiency gains may be more effective than appealing to moral norms in contexts analogous to the Stag‑Hunt.