Warneken, F., Lohse, K., Melis, A. P., & Tomasello, M. (2011). Young children share the spoils after collaboration. Psychological Science, 22(2), 267–73. http://doi.org/10.1177/0956797610395392
1) The authors postulate that the relationship between joint collaboration and sharing is crucial for understanding the origins of equality, both in ontogeny and phylogeny. Therefore, they investigate how children actively divide rewards after working for them in a collaborative problem-solving task.
Most studies on sharing involve windfall situations, in which resources are given to the children by a third party, with no work or effort involved. Moreover, many studies use a forced-choice paradigm with predefined allocation options, which does not allow for an assessment of how children themselves would actively negotiate over how to distribute resources with another person.
In contrast, Warneken et al.’s research is guided by the notion that people often have to work toward obtaining resources, and that they distribute those resources actively, rather than choosing individually between predefined options. Previous studies, they say, have not shown how children share resources in situations that might be the cradle of equality: actual joint collaborative activities with a social partner.
2) The experiment closely resembles sharing experiments with chimpanzees and other non-human primates. Warneken et al test children in dyads. Children have to perform a task together: they have to pull from both ends of a rope at the same time in order to bring a box close to them. In this way, they are able to get a reward (such as stickers or candy that have been placed in the box). In one condition, the box has two holes far apart, so that each child can get her reward without interference from the other participant. In a second (“clumped”) condition, the box has only one hole, and therefore only one child can access the rewards at a time.
3) Warneken et al. found that neither the reward type nor the opportunity to monopolize rewards in the clumped condition interfered with the children’s collaboration. 3 year-olds collaborate successfully in situations in which resources can be monopolized. The collaborative abilities of young children, compared with those of chimpanzees, are not constrained to the same extent by a tendency to monopolize resources.
Children predominately produced equal shares. They shared rewards equally most of the time, even when rewards could be monopolized more easily (clumped condition). At an age when children are just beginning to skillfully collaborate with peers, they already engage in sharing behavior that results in equitable outcomes.
4) What does it all mean? Competition over resources, the authors claim, is mitigated in human children (when compared with chimpanzees and other primates) by an emerging sense of equal sharing of the spoils, which enables successful collaboration even early in ontogeny. Thus, the authors claim that this study supports a Tomasello-like evolutionary hypothesis, according to which the emergence of cooperation is due not only to cognitive and behavioral skills, but also to a reduction in competition over resources. Competition over resources is mitigated in human children by an emerging sense of equal sharing of the spoils, which enables successful collaboration even early in ontogeny.
5) According to this study, children are capable of equitable distributions a very early age. Although many studies place the origins of equality at around 5, 6 or even 7 years of age, it all depends on how the concrete distribution problem is presented to the children. Warneken et al. present children with a collaborative, non-competitive situation. In addition, in this study the peer is present; the dyad works together in a problem solving activity (compare this with economic games that are played by a single present individual and an absent, anonymous, “invisible”). Even more, some of the dyads comprise children who know each other well, since they attend the same day-care center (they are not one-shot interactions, as in most economic games). All this seems to help even 3 year-olds to produce equitable outcomes early in development. The authors reach the conclusion that, perhaps, children learn to acknowledge each other’s right to gain equal resources in situations in which they collaborate to produce a mutually beneficial outcome that one person acting alone would not be able to achieve (this result is not proven by the experiment, in my opinion).