© Max Planck Society
Cooperative behaviour is generally associated with personal disadvantage. Scientists have therefore long been unable to explain why, despite this, altruism exists in nature. However, altruistic behaviour can be successful if organisms improve their reputation through unselfish behaviour and can benefit from it at a later stage: those who give receive; but those who refuse to lend support cannot expect help in an emergency. Solidarity is also the outcome of social evolution in humans. However, altruism can only enhance an individual’s reputation and prevail if the corresponding behaviour is known to others.
Thus, people behave more cooperatively when they are observed. Accordingly, as soon as they are aware that they are being observed, egoists try to conceal their behaviour and pretend to act cooperatively. The observer, in turn, would like to prevent this and tries to conceal his or her attention. The researchers from Cologne and Plön discovered this interaction with the help of public goods games, in which the participants could benefit from egoistic behaviour. Their experiments showed that external observers prefer people who show solidarity as future game partners. Moreover, they are willing to pay to conceal their observation of another player. The players were also willing to pay to conceal egoistic behaviour. “A kind of ‘arms race’ thus arises between the two parties. They both want to keep their intentions secret from the other,” says Manfred Milinski from the Max Planck Institute for Evolutionary Biology.
Interestingly, observers seldom select people who punish others for egoistic behaviour. In effect, such sanctions are an expression of altruistic behaviour, as they are associated with personal costs incurred for the general good. “A person who observes other people with a view to finding cooperative partners would be expected to take punishment behaviour into account. The finding that people do not use this information raises important new research questions,” says Bettina Rockenbach from the University of Cologne.
The researchers also observed that people prefer to hide the fact that they have punished others for egoistic behaviour. This is also surprising as punishments can be justified in terms of concern for the general good. Despite this, people apparently fear for their reputation if they punish others severely for egoistic behaviour. This finding is all the more unexpected as the tests showed that observers do not attach any importance to this information.
The researchers analysed three variants of a public goods game in their study. In all three games, the participants were accompanied by an observer who, after 15 rounds of the game, could remove a random or specific player and play himself; the replacement of a specific player incurred a cost. The observer could also conceal which players he or she was observing at a cost. The players, in turn, could pay to ensure that the observer did not find out anything about a decision.
In the simple variant of the game, a group of four participants merely had to decide between uncooperative and cooperative behaviour. They were given an actual sum of money and could decide whether to pay part of it into a shared kitty or keep all of it for themselves. At the end of the round, the sum in the group kitty was doubled and distributed evenly among the participants. The more players that paid into the kitty, the more they all benefited from it – however, the egoists profited most at the cost of the altruists. Under these conditions, egoistic behaviour prevailed after a few repetitions of the game.
In contrast, altruistic behaviour could prove a successful strategy in the other two variants of the game. Each of the participants was able impose punishments on the other players upon completion of a round of the public goods game. The punishments were withdrawn from the account of the individual in question and he or she also had to contribute something for the punishment. In the third variant, having been informed about the contributions received and made by the potential recipient, each of the participants was able to make contributions to one of the other players and receive them from another depending on whether he or she had improved his reputation by paying into the group kitty.