Fairness takes time: Development of cooperative decision making in fairness context.

The current study examined the development of fairness behavior and tested whether children's fair choices are fast and intuitive or slow and deliberate. Reaction times were measured while 4- to 9-year-olds (N = 94, 49 girls, 84.6% White) completed a novel social decision-making task contrasting fair choices with selfish choices. Fairness behavior increased during childhood, shifting from predominantly selfish choices among young children to fair choices by 7 years of age. Moreover, young children's fair choices were slow and deliberate, whereas reaction times did not predict older children's choices. These findings contrast with adults' intuitive cooperation and point to protracted development and learning of cooperative decision making in fairness contexts.