title: The shadow of the future promotes cooperation in a repeated prisoner's dilemma for children.
abstract: Cooperation among genetically unrelated individuals can be supported by direct reciprocity. Theoretical models and experiments with adults show that the possibility of future interactions with the same partner can promote cooperation via conditionally cooperative strategies such as tit-for-tat (TFT). Here, we introduce a novel implementation of the repeated Prisoner's Dilemma (PD) designed for children to examine whether repeated interactions can successfully promote cooperation in 10 and 11 year olds. We find that children cooperate substantially more in repeated PDs than in one-shot PDs. We also find that girls cooperate more than boys, and that children with more conduct problems cooperate less. Finally, we find that children use conditional cooperation strategies but that these strategies vary by gender and conduct problem rating. Specifically, girls and children with few conduct problems appear to follow an altruistic version of win-stay, lose-shift (WSLS), attempting to re-establish cooperation after they had defected. Boys and children with more conduct problems appear to follow a Grim strategy, defecting for the duration after the partner defects. Thus we provide evidence that children utilize the power of direct reciprocity to promote cooperation in strategic interactions and that, by late elementary school, distinct strategies of conditional cooperation have emerged.
authors.affiliation: Boston University, Department of Psychological and Brain Sciences, 64 Cummington Mall, Boston, MA 02215.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Blake
authors.affiliation: Yale University, Department of Psychology, Department of Economics, School of Management, 2 Hillhouse Ave, New Haven, CT 06520.
authors.forename: David G
authors.initials: DG
authors.lastname: Rand
authors.affiliation: Harvard University, Department of Government, 1737 Cambridge St, Cambridge, MA 02138.
authors.forename: Dustin
authors.initials: D
authors.lastname: Tingley
authors.affiliation: Harvard University, Department of Psychology, 33 Kirkland Street, Cambridge, MA 02138.
authors.forename: Felix
authors.initials: F
authors.lastname: Warneken
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D003299:Cooperative Behavior; D005260:Female; D005716:Game Theory; D006801:Humans; D008297:Male; D000068956:Prisoner Dilemma