Imagine that somebody offers you 1000 Euros. All you have to do is agree with some other anonymous person on how to share the sum. The two of you are in separate rooms and cannot exchange information. You can make a single offer of how to split the sum, and the other person (who knows the total amount of money at stake) can accept or reject it. If he accepts it the deal goes ahead. If he rejects it, both of you go away empty-handed. It is a one-shot game, and you will never meet your playmate again. What will you do?

"Standard" Game Theory predicts an unequal split favoring the person who gets to make the offer. The proposer will make the smallest possible offer and keep the rest (if the offer is zero, the responder is indifferent between rejecting and accepting). Real world is different, however. You may not be suprised to learn that mean offers in industrial societies are typically close to 44 percent. News: In "In Search of Homo Economicus: Behavioral Experiments in 15 Small-Scale Societies" a bunch of economists showed that there were sizeable differences in the way some people play the Ultimatum Game (henceforth UG). To me this is the most interesting part:

"The large variations across the different cultural groups [three foraging societies, six that practice slash-and-burn horticulture, four nomadic herding groups, and three sedentary, small-scale agriculturalist societies] suggest that preferences or expectations are affected by group-specific conditions, such as social institutions or cultural fairness norms. We rank-ordered the societies along two dimensions:

(i) Payoffs to cooperations (PC): How important and how large is a group's payoff from cooperation in economic production?

(ii) Market integration (MI) - How much do people rely on market exchange in their daily lives?

On the first dimension, payoffs to cooperation, the Machiguenga and Tsimané rank the lowest; they are almost entirely economic independent at the family level and engage rarely in productive activities involving more than members of a family. By contrast, the Lamelara whale-hunters go to sea in large canoes manned by a dozen or more individuals. The rationale for PC as a predictor of UG offers is that with little cooperative production there will be little necessity to share returns, while those whose livelihood depends on large-scale cooperation like the Lamelara must develop ways of sharing the joint surplus. Thus we might expect that a higher level of PC will increase sharing behavior in the UG. The rationale for market integration as an explanatory variable is that the more frequently people experience market transactions, the more they will also experience abstract sharing principles concerning behaviors toward strangers of which the UG is an example. <cut*> A plausible interpretation of our subjects behaviors is that, when faced with a novel situaton (the experiment), they looked for analogues in their daily experience, asking "What familiar situation is this game like?" and then acted in a way appropriate for the analogous situation".... come on, read the article, it's great.

Thanks to zeitgenossen for that pointer!

If you are looking for a more general treatment read "The economics of fair play" (Scientific American) by Karl Sigmund, Ernst Fehr and Martin Nowak. Karl Sigmund is the uncle of Michael Sigmund. I sued that guy last winter for deliberately smashing me against a wall.

cut*: They did run some regressions but unfortunately shunned to tell how they actually measured PC and MI. I am also pretty sure that they created the variables after observing the group outcomes.