Children use rules to coordinate in a social dilemma.
Humans are frequently required to coordinate their actions in social dilemmas (e.g. when one of two drivers has to yield for the other at an intersection). This is commonly achieved by individuals following communally known rules that prescribe how people should behave. From relatively early in development, children swiftly pick up the rules of their culture and even start creating game rules among peers. Thus far, however, little is known about children's abilities create rules to regulate their own interactions in social dilemma situations in which individuals' interests are partially in conflict. Here, we repeatedly selected dyads of children (5- and 8-year-olds, N = 144) at random from a group and presented them with a chicken game - a social dilemma in which individuals have conflicting motives but coordination is required to avoid mutual failure. In game breaks, groups reconvened and had the opportunity to think of additional game rules. Eight- but not five-year-olds readily came up with and agreed upon impartial rules to guide their subsequent game behavior (but only after adult prompting). Moreover, when playing by the self-made rules, children achieved higher payoffs, had fewer conflicts, and coordinated with greater efficiency than when playing without a rule - which mimics the functional consequences of rules on a societal level. These findings suggest that by at least age 8, children are capable of using rules to independently self-regulate potential conflicts of interest with peers.