Experimenting with Social Norms, edited by Jean Ensminger and Joseph Henrich, compiles and synthesizes a rich combination of experimental and ethnographic findings from an international team of anthropologists and economists aimed at investigating the tensions between cooperation and self-interest across diverse human societies. How do societies manage to solve problems collectively, enticing individuals to forego their own narrow short-term economic interests in a way that benefits the whole group, and fosters mutually beneficial exchange? And furthermore, how does the decision to subordinate one’s self-interests for the larger group—or what Ensminger and Henrich call prosocial behavior—vary among different societies based on locally acquired social norms and motivations?

Using experimental economics games, this team examined levels of fairness, cooperation, and norms for punishing those who violate expectations of equality across a diverse swath of societies, from hunter-gatherers in Tanzania to a small town in rural Missouri. The researchers employed the following games to assess each group’s level of prosociality:

Dictator Game
Two players from the same community, interacting anonymously, are given a sum of money equivalent to one day’s wages to split. Player 1, assigned to be the “dictator,” decides how to allocate the money between the two players. Both players receive the actual amounts of money that Player 1 “dictates.” In Europe and the U.S. a fifty-fifty split is considered a “fair” outcome.

Ultimatum Game
This version of the dictator game adds an ultimatum: Though Player 1 decides how to allocate the money, Player 2 may reject the offer—in which case, neither party receives anything. The behavior of Player 1 in this scenario has elements of both fairness and strategy, while the behavior of Player 2 in this game captures the price that people are willing to pay to punish Player 1 for what they perceive to be an unfair offer. The willingness to punish an anonymous partner for unfairness, at a personal monetary cost, can be interpreted as prosocial behavior because this punishment may alter Player 1’s future interactions with other group members.

Third-Party Punishment Game
In this experiment, two people play the Dictator Game with the addition of a third anonymous player— endowed with an amount of money equivalent to half the amount given to the first two players—who has the option of using any part of his or her money to punish Player 1 for making an unfair offer to Player 2. Unlike the Ultimatum Game, in the Third-Party Punishment Game, the person paying a price to do the punishing is not the injured party.

If the players in these games were strictly rational, money-maximizing actors, one would expect them to behave in ways that secured them the largest amount of money by the game’s conclusion. In the Dictator Game, this would entail Player 1 keeping all of the money to him or herself; in the Ultimatum Game, this would entail Player 2 accepting any amount of money higher than 0 and the proposer consequently making a low offer. But, as Ensminger and Henrich observe, researchers looking across a wide range of societies found that people do not play these games strictly as money-maximizers. They found that in particular, societies with developed, stable economies, and an orientation toward a world religion (such as Judaism, Islam, or Christianity) displayed higher levels of prosocial behavior. We see this clearly in the plot below of Dictator Game offers, where societies with the lowest level of market integration (hunters, gatherers and horticulturalists) make the lowest offers, and those with full-blown market economies make the highest offers, approaching 50 percent.

In one case study, Ensminger and anthropologist Kathleen Cook ran a series of experimental games in the rural Bible-belt town of Hamilton, Missouri. They found levels of prosociality that were markedly higher than those previously observed in U.S. undergraduate students, but similar to those from other studies of non-student populations in developed societies. In Hamilton, players assigned to be the “dictator” in the Dictator Game consistently gave 50% of the money (which was set at roughly the daily minimum wage, or $50). As the chart below shows, nearly 100% of the “dictators” split the amount of money fairly with the other player:

The results for the Ultimatum Game also demonstrated strong tendencies toward prosociality in the Hamilton sample. As the graph below shows, players were likely to reject offers that seemed unfair. The majority of players rejected offers up to 30% of the money—with close to 30% of the players rejecting offers as high as 40%—representing extremely vigilant behavior regarding fairness:

The Hamilton study (Ensminger and Cook) further confirmed the researchers’ findings that higher levels of prosociality occur within societies with developed markets and an orientation toward a world religion.

The fifteen case studies in the book, available for free download from the Russell Sage Foundation’s website, provide an in-depth analysis of the social behaviors from a wide range of global societies. Click here to read more and download each case study.