Reciprocity and the tragedies of maintaining and providing the commons

Social cooperation often requires collectively beneficial but individually costly restraint to maintain a public good, or it needs costly generosity to create one. Status quo effects predict that maintaining a public good is easier than providing a new one. Here, we show experimentally and with simulations that even under identical incentives, low levels of cooperation (the ‘tragedy of the commons’) are systematically more likely in maintenance than provision. Across three series of experiments, we find that strong and weak positive reciprocity, known to be fundamental tendencies underpinning human cooperation, are substantially diminished under maintenance compared with provision. As we show in a fourth experiment, the opposite holds for negative reciprocity (‘punishment’). Our findings suggest that incentives to avoid the ‘tragedy of the commons’ need to contend with dilemma-specific reciprocity.

社会合作往往需要付出个体代价但能带来集体收益的克制行为，以维持公共物品（public good）；或是需要付出个体代价的慷慨行为，来创造公共物品。现状效应（Status quo effects）预测，维持公共物品比创造全新公共物品更为容易。本研究通过实验与模拟研究证实，即便激励条件完全一致，公共物品维持场景下的合作水平低下（即「公地悲剧（tragedy of the commons）」）的发生概率，系统性地高于公共物品创造场景。在三组系列实验中，我们发现，作为支撑人类合作的核心倾向的强正向互惠与弱正向互惠，在维持场景下相较于创造场景出现了显著弱化。正如第四项实验所展示的，负向互惠（即「惩罚（punishment）」）则呈现出相反的结果。本研究结果表明，规避「公地悲剧」的激励措施，需要针对性应对不同困境下的互惠行为模式。