poly: Science News on conditional cooperation

From: Hal Finney <hal@rain.org>
Date: Wed Apr 08 1998 - 12:37:56 PDT

The March 28 issue of Science News has an article on economic experiments
in which cooperation occurs in situations where a strictly rational
analysis would predict uncooperative behavior.

One example given is ultimatum games. Here, a sum of money is offered
to two players if they can agree to accept it. The first player, the
proposer, offers some part of the total to the second player, the
responder. If the responder accepts his portion, both players receive
the money. Otherwise they get nothing. These games are one-shot and
there is no opportunity for the participants to communicate or bargain
during the game.

Rationally, the first player should offer the second player the minimum
sum possible, and the responder should accept it. If the amount of money
being offered is $100, the proposer would suggest that he keep $99.99
and give $.01 to the responder. The responder should accept since he
gets more this way than if he refuses.

According to the article, studies in a variety of countries find instead
that proposers instead offer 30% to 40% of the total. Most responders
accept such offers, but reject anything less than about 20%.

"In high-stakes ultimatum games, such as a study in which pairs of
Indonesian volunteers received sums equivalent to 3 months' salary, most
propsers offer 50 percent of the total, which responders overwhelmingly

It is suggested that notions of "fairness" evolve in societies in which
there are many interactions with strangers, and that these principles
guide behavior in such experiments. One theorist, David Sloan Wilson,
is characterized as believing that people evolve genetic traits geared
towards the interests of groups and not just individuals, a controversial

Received on Wed Apr 8 19:46:29 1998

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