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Prof. Manfred Milinski
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Publication references

Manfred Milinski, Dirk Semmann, Hans-Jürgen Krambeck, Jochem Marotzke
Stabilizing the Earth’s climate is not a losing game: supporting evidence from public goods experiments

People want to be seen helping the climate

Max Planck researchers find that a person is more likely to help protect the climate when receiving public recognition for it

March 02, 2006

The global climate can be thought of as a public good. But how can we encourage people to invest their energies altruistically in its maintenance? This question was addressed experimentally by researchers from the Max Planck Institutes of Limnology in Plön, and Meteorology in Hamburg, Germany. The test subjects were given the choice of spending money on a magazine advertisement meant to inform the public about basic rules of climate preservation and the consequences of climate-unfriendly behaviour. The result: people are more likely to work toward common goals when they are well-informed and when they receive public recognition for their good deed - which can be of as much value to them as money (PNAS, February 28, 2006).
Players’ investments. "Well informed" game rounds are in red, "little informed" in blue. If the players were completely anonymous, their marks are emp Zoom Image
Players’ investments. "Well informed" game rounds are in red, "little informed" in blue. If the players were completely anonymous, their marks are empty. If they were recognised with pseudonyms, their marks are coloured. The result: Informed, non-anonymous players contributed the most money each round. [less]

Psychologists, sociologists, and game theorists have long looked at the relationship between altruism and egoism. A classic is one in which four subjects receive 10 euros each. In each round, they are allowed to put between 0 and 10 euros into a common pool of money without their fellow subjects knowing how high the sum is. The experimenter collects the contributions, doubles the amount, and then divides this money evenly among the players.

If everyone gives everything they have, they all get double as much back. But if only an individual player donates and others do not, then she loses half her contribution, and other players profit without the risk of loss. Normally, no one pays voluntarily into the pool; it is the only way of avoiding the high risk of loss.

The Max Planck researchers carried out a variation on this experiment. They told the players that their contribution would not be distributed back to them, but rather doubled and put into a magazine advertisement. The Max Planck Institute for Meteorology would inform the public about the condition and expectations for the global climate. In the advert there would be a list of simple but effective rules about how each person can reduce their carbon dioxide emissions.

The players - 156 students from Hamburg - made their contributions to the advertisement pool either in public or, every second round, anonymously. Between rounds of this experiment, another game was played, in which it was important to have a good "reputation". Each player was asked if he wanted to give money to another player. If yes, the receiver would get double the amount the donor pledged. Beforehand, the donor and all the other players were informed how much the receiver paid during non-anonymous climate rounds and reputation rounds. In this way, their contribution to climate preservation, and their donations to people who contributed to the climate pool, could be rewarded. Each second group of six players also received scientific information about the causes and consequences of climate change.

The results surprised the researchers. All the players donated to the advertisement. The largest donors were players informed about climate change who could publicly contribute to the pool (see image). In the reputation rounds, donors preferred to give to receivers that had previously given to the climate pool. Very little was contributed to the pool anonymously. Thus, there is a pay off for people who invest in climate preservation when doing so also improves their reputation: "Do good when others can see it." Being scientifically informed also had a significant effect on subjects’ readiness to invest in climate maintenance, either publicly or anonymously.

The scientists advise politicians to develop better strategies to publicise people’s investments in climate preservation.

 
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