Fairness, or the ability to distribute resources in a manner thataccords with societally recognized principles of justice, is ahallmark of human cooperation. Young children rapidlydevelop the ability to enact fairness, but the cognitiveunderpinnings of this ability remain unknown. The presentstudy investigated 4-7-year-olds’ acquisition of threeprinciples of fairness -- equality (the principle that all partiesshould have the same), merit (the principle that those whowork harder should get more), and starting opportunity (theprinciple that those who started with less should get more) --in relation to their emerging cognitive control and memory fornumerical information (numerical accuracy). Cognitivecontrol predicted children’s equal sharing, whereas numericalaccuracy predicted merit-based sharing. Children up throughthe oldest age we tested ignored starting opportunities. Theresults suggest that different principles of fairness may beunderpinned by distinct cognitive processes.

How can social learning influence children’s inclinationstoward equality-based or merit-based fairness? To investigatethis question, six- and seven-year-olds were first presentedwith a pre-test distribution task in which they divided eightstickers between two hypothetical children, one of whom wasa more productive worker. Participants were then given brief,direct testimony that advocated either equality- or merit-basedfairness (whichever was not preferred at pre-test), and thatappealed either to emotions or reason. A novel experimenterthen presented participants with a post-test distribution task.The results indicated that a majority of children changed theirdistribution patterns from pre-test to post-test after beingprovided with direct testimony. These changes in resourcedistribution were accompanied by marked changes in thekinds of explanations that children provided. This researchindicates that children’s preferences for different forms of justresource distribution can be heavily influenced by socialcommunication.