Neuroscientists find that children’s counting ability predicts merit-based sharing
Children can divide resources in different ways: give everyone an equal share, or reward those who contributed more with a larger portion. Research shows that young children often default to equal divisions, but as they grow older they tend to shift toward merit-based allocations, where effort or contribution determines who receives more.
New work by neuroscientists from MIT and the University of Rochester shows that this developmental shift is strongly linked to children’s ability to count. In a study of children from the Tsimane’ community in the Bolivian Amazon—where children learn counting at widely varying ages—counting skill emerged as the strongest predictor of whether a child would share based on merit rather than equality.
Julian Jara-Ettinger, the study’s lead author and then a graduate student at MIT, describes the effect as “very strong.” The paper’s senior author, Steve Piantadosi, completed the research while at MIT and is now an assistant professor at the University of Rochester. The findings appear in the journal Developmental Science.
Calculating merit
Prior research has documented the transition from egalitarian sharing to merit-sensitive sharing, but disagreement persists over when and why that change happens. Many studies suggest the shift typically occurs around ages 5 to 6. Other experiments indicate that even children as young as 3 can favor the higher-performing person, but only in forced-choice situations where division cannot be even—such as when one extra item must be allocated.
Edward Gibson, a professor of brain and cognitive sciences at MIT and a coauthor of the study, notes that younger children do understand who worked harder, but they may lack the tools to translate that understanding into precise divisions. “It’s not that they don’t grasp the idea of more merit,” he says. “They often simply don’t know how to carry out the distribution accurately.”
To test the relationship between counting ability and sharing behavior, the researchers returned to the Tsimane’ community where earlier work had shown wide variation in the age at which children acquire counting skills—typically between about 5 and 8 years old. This variation allowed the team to separate number knowledge from chronological age and school exposure.
Across two field visits in 2013 and 2014, the team tested 70 Tsimane’ children aged 3 to 12. Each child viewed two drawings of identical-looking children wearing shirts of different colors and was told a simple story: one child had worked very hard and collected 18 bananas, while the other had gathered only 4. Experimenters then handed the participant an even number of paper “cookies” and asked them to distribute the cookies as a reward.
Researchers also assessed each child’s counting ability using the same measure applied in their earlier study. Statistical analysis revealed that counting competence strongly predicted whether children allocated more cookies to the higher-effort child. In contrast, chronological age and years of schooling did not reliably predict merit-based allocations in this sample.
Susan Levine, a psychology professor at the University of Chicago who was not involved with the project, emphasizes the broader significance: understanding numbers shapes not only mathematical reasoning but also social judgments about fairness. “Number knowledge influences how children turn ideas about deservingness into concrete sharing decisions,” she says.
Manipulating objects and measuring sets
The researchers argue that the key barrier for younger children is not the moral or social concept of merit, but the cognitive ability to manipulate numerical sets. In a related, unpublished study they report that learning to count coincides with a better grasp of how sets of objects change when items are added or removed.
“Once children understand how quantities change when you manipulate them, they can more fluently convert the judgment that someone deserves more into an exact portion to give,” Jara-Ettinger explains. That improved fluency in tracking and transforming sets appears to enable merit-based sharing.
Among the study’s authors, Celeste Kidd at the University of Rochester is now exploring whether the same link between counting and merit-based distribution appears in children in the United States, where counting typically begins earlier, around ages 3 to 4.
Source: MIT newsroom reporting by Anne Trafton
Image credit: Adapted from the original MIT press release
Original research: The study is titled “Native Amazonian children forego egalitarianism in merit-based tasks when they learn to count,” authored by Julian Jara-Ettinger, Edward Gibson, Celeste Kidd, and Steve Piantadosi, and published in Developmental Science in 2015.
Abstract
Deciding how to divide the material rewards of cooperation can follow different fairness principles: equal rewards for all (egalitarian) or rewards proportional to each person’s contribution (merit-based). This study tests whether acquiring numerical concepts shapes how children reason about fairness. The research focuses on the Tsimane’, a farming-foraging society in the Bolivian rainforest, where children learn counting later and more variably than in many industrialized contexts. Because number learning is decoupled from age and schooling in this population, the researchers could examine the influence of counting itself. They found that Tsimane’ children who can count tend to produce merit-based distributions, while children who cannot count produce a mix of merit-based and egalitarian distributions. These results indicate that the culturally invented skill of counting can alter social cognition about fairness and resource allocation.
Study citation: “Native Amazonian children forego egalitarianism in merit-based tasks when they learn to count,” Julian Jara-Ettinger, Edward Gibson, Celeste Kidd, and Steve Piantadosi. Developmental Science, published online October 21, 2015.