Our willingness to engage in punitive acts is a key part of our society. So claims a recent article in Science. Through the experiments of Milgram, Asch, Zimbardo, and Sherif psychologists have studied humans' engagement in costly social relationships with non-kin. With many of these experiments being done in students only, it has been hard to extrapolate the results to the entire population. Understanding different cultures through these experiments is even worse.
In this week's Science report, a team of scientists studied social interaction in different cultures, using three different social psychology experiments. The first was an ultimatum game:
(…) two anonymous players are allotted a sum of real money (the stake) in a one-shot interaction. The first player (player 1) can offer a portion of this sum to a second player, player 2 (offers were restricted to 10% increments of the stake). Player 2, before hearing the actual amount offered by player 1, must decide whether to accept or reject each of the possible offers, and these decisions are binding. If player 2 specified acceptance of the actual offer amount, then he or she receives the amount of the offer and player 1 receives the rest. If player 2 specified a rejection of the amount actually offered, both players receive zero. If people are motivated purely by self-interest, player 2s will always accept any positive offer; knowing this, player 1 should offer the smallest nonzero amount. Because this is a one-shot anonymous interaction, player 2's willingness to reject provides one measure of costly punishment, termed second-party punishment
The second game was a party punishing game (PDF):
(…) two players are allotted a sum of real money (the stake), and a third player gets one-half of this amount. Player 1 must decide how much of the stake to give to player 2 (who makes no decisions). Then, before hearing the actual amount player 1 allocated to player 2, player 3 has to decide whether to pay 10% of the stake (20% of his or her allocation) to punish player 1, causing player 1 to suffer a deduction of 30% of the stake from the amount kept. Player 3s punishment strategy is elicited for all possible offers by player 1. For example, suppose the stake is $100: if player 1 gives $10 to player 2 (and keeps $90) and player 3 wants to punish this offer amount, then player 1 takes home $60; player 2, $10; and player 3, $40. If player 3 had instead decided not to punish offers of 10%, then the take-home amounts would have been $90, $10, and $50, respectively. In this anonymous one-shot game, a purely self-interested player 3 would never pay to punish player 1. Knowing this, a self-interested player 1 should always offer zero to player 2. Thus, an individual's willingness to pay to punish provides a direct measure of the person's taste for a second type of costly punishment, third-party punishment.
The third game was a dictator game:
The [dictator game] is the same as the [ultimatum game] except that player 2 cannot reject. Player 1 merely dictates the portions of the stake received by himself or herself and player 2. In this one-shot anonymous game, a purely self-interested individual would offer zero; thus, offers in the [dictator game] provide a measure of a kind of behavioral altruism that is not directly linked to kinship, reciprocity, reputation, or the immediate threat of punishment.
Regardless of culture, the findings showed that the two measures of costly punishment produced an increasing proportion of individuals choosing to punish as offers approach zero. But there were substantial cultural differences also, especially in terms of people's overall willingness to punish unequal offers. In some cultures, offers as low as 10% were accepted without punishment, while other cultures were less inclined to reject such a deal.
How do these cultural differences come to be? Is there a relationship between people's willingness to share (altruism) and a culture's level of costly punishment? The researchers plotted the relationship between the minimal offers that cultural groups were to accept (x axis) and the mean offer from the dictator game (y axis):
These results demonstrate that there is a positive relationship between the likelihood of accepting an offer (i.e. the level of willingness to punish small offers) and the willingness to share (i.e. altruism). In other words, in cultures where you are expected to share, you give more, even thought others have no way to threaten or punish you.
The researchers conclude:
These three results are consistent with recent evolutionary models of altruistic punishment. In particular, culture-gene coevolutionary models that combine strategies of cooperation and punishment predict that local learning dynamics generate between-group variation as different groups arrive at different "cultural" equilibria. These local learning dynamics create social environments that favor the genetic evolution of psychologies that predispose people to administer, anticipate, and avoid punishment (by learning local norms). Alternative explanations of the costly punishment and altruistic behavior observed in our experiments have not yet been formulated in a manner that can account for stable between-group variation or the positive covariation between altruism and punishment. Whether the co-evolution of cultural norms and genes or some other framework is ultimately correct, these results more sharply delineate the species-level patterns of social behavior that a successful theory of human cooperation must address.