Pistes Psychologiques Sur L'existence De L'état

[Punu]

Human behaviour: Don't lose your reputation

News and Views

Nature 432, 449 - 450 (25 November 2004); doi:10.1038/432449a

ERNST FEHR

Ernst Fehr is at the Institute for Empirical Research in Economics,

University of Zurich, Blumlisalpstrasse 10, CH-8006 Zurich, Switzerland.

e-mail: efehr@iew.unizh.ch

Collective action in large groups whose members are genetically

unrelated is a distinguishing feature of the human species. Individual

reputations may be a key to a satisfactory evolutionary explanation.

When the Allied forces invaded Normandy during the Second World War,

thousands of people were involved in the preparations and in the

invasion itself; a similar number of Germans were probably involved in

defending the occupied territory. War is a prime example of large-scale

within-group cooperation between genetically unrelated individuals (Fig.

1). War also illustrates the fact that within-group cooperation often

serves the purpose of between-group aggression. Modern states are able

to enforce cooperation in large groups by means of sophisticated

institutions that punish individuals who refuse to meet their duties and

reward those who follow their superiors' commands. The existence of such

cooperation-enhancing institutions is very puzzling from an evolutionary

viewpoint, however, because no other species seems to have succeeded in

establishing large-scale cooperation among genetically unrelated strangers.

The puzzle behind this cooperation can be summarized as follows.

Institutions that enhance within-group cooperation typically benefit all

group members. The effect of a single group member on the institution's

success is negligible, but the contribution cost is not negligible for

the individual. Why, therefore, should a self-interested individual pay

the cost of sustaining cooperative institutions? More generally, why

should a self-interested individual contribute anything to a public good

that — once it exists — an individual can consume regardless of whether

he contributed or not? On page 499 of this issue, Panchanathan and Boyd

substantially advance the scope of reputation-based models3-5 and show

that individuals' concern for their reputation may be a solution to this

puzzle.

Evolutionary psychologists have sought to answer the puzzle of human

collective action for decades. However, progress was limited because of

a lack of commitment to mathematically rigorous theorizing. Many

researchers erroneously thought that Trivers's notion of reciprocal

altruism, which Axelrod and Hamilton successfully formalized as a

tit-for-tat strategy for two-person interactions, provides the solution

to the problem. Trivers himself speculated that reciprocal altruism "may

favour a multiparty altruistic system in which altruistic acts are

dispensed freely among more than two individuals". However, it is always

easier to speculate than to provide a rigorous model, and the

speculation is likely to be wrong in this case.

In the context of the problem of public-goods provision, a reciprocally

altruistic individual is willing to contribute to the public good if

sufficient numbers of other group members are also willing to

contribute. Unfortunately, the presence of only a small number of

defectors quickly causes cooperation to unravel if it is solely based on

conditionally cooperative behaviour, because the defectors induce the

conditional cooperators to defect as well. Theory and simulations

suggest that reciprocally altruistic strategies can only sustain high

levels of cooperation in two-person interactions. Moreover,

experimental evidence indicates that cooperation in public-good games

typically unravels because it is not possible to discipline 'free

riders' — those who take advantage of others' cooperation — if only

conditionally cooperative strategies are available.

In contrast to reciprocal altruism, the notion of altruistic punishment

has been more successful in explaining collective action, because direct

punishment disciplines free riders. Altruistic punishers contribute to

collective actions and are willing to sanction individual defectors even

if they incur net costs by doing so. However, within-group selection in

the presence of altruistic punishers favours cooperative individuals who

do not punish defectors. Such individuals will never be punished —

because they contribute to the collective action — but they also never

bear the cost of punishing defectors. These pure cooperators are thus

'second-order' free riders because they do not contribute to the

disciplining of the selfish individuals. Therefore, pure cooperators

will crowd out altruistic punishers unless there is group competition

that renders groups with a higher share of altruistic punishers more

successful.

Full Text at Nature

http://www.nature.com/cgi-taf/DynaPage.taf…432449a_fs.html

Impulsive behavior may be a relic of hunter-gatherer past

Posted Dec. 14, 2004

Courtesy the University of Minnesota

Drawing on experiments with blue jays, a team of University of Minnesota researchers has found what may be the evolutionary basis for impulsive behavior. 

Such behavior may have evolved because in the wild, snatching up small rewards like food morsels rather than waiting for something bigger and better to come along can lead to getting more rewards in the long run, researchers said. 

The work may help explain why many modern-day humans find it so hard to turn down an immediate reward--for example, food, money, sex or euphoria--rather than investing and waiting for a bigger reward later. The work will be published in the Dec. 7 issue of the research journal Proceedings of the Royal Society (London).

In experiments with blue jays, David Stephens, a professor of ecology, evolution and behavior in the university’s College of Biological Sciences, found that birds presented with a choice of getting a small food reward immediately or waiting a short time for a bigger one could not be trained to wait, even after a thousand repetitions. 

Many researchers have explained such impulsiveness as the result of the bird “discounting” the value of a delayed reward--that is, instinctively realizing that a reward delayed may be a reward denied because conditions can change while the bird is waiting. But the birds’ impulsiveness was simply too strong to explain that way, Stephens said.

“I think we were asking them the wrong question,” he explained. “In nature, they don’t often encounter a situation where they must give up a better, but delayed, food morsel when they grab a quick meal. So we designed an experiment that better modeled real life in the wild.”

The new experiments were modeled on how animals encounter and exploit food clumps. The jays encountered one clump at a time and obtained some food from it. Then they had to decide whether to wait for a bit more from the same clump or leave and search for another clump. 

Not surprisingly, the birds still acted impulsively, preferring items they could get quickly. They considered only the size and wait time for their next reward--never a reward beyond that, even though it may have been bigger.

What did surprise Stephens was that the birds that went for the immediate reward were able to “earn” as much or more food in the long run as birds that were forced to wait for the larger reward or to follow a mixed strategy. The reason, he said, was that in the wild, animals aren’t faced with an either-or choice of “small reward now or big reward later.” What happens is that when they find a small bit of food, they don’t wait; they just go back to foraging, and they may find lots of little rewards that add up to more than what they would get if they had to hang around waiting for bigger and better.

“Animals, I think, come with a hardwired rule that says, ‘Don’t look too far in the future,’“ Stephens said. “Being impulsive works really well because after grabbing the food, they can forget it and go back to their original foraging behavior. That behavior can achieve high long-term gains even if it’s impulsive.”

The work may apply to humans, he said, because taking rewards without hesitation may have paid off for our foraging ancestors, as it does for blue jays and other foragers. Modern society forces us to make either-or decisions about delayed benefits such as education, investment and marriage; the impulsive rules that work well for foragers do more harm than good when applied in these situations.

“Impulsiveness is considered a big behavior problem for humans,” said Stephens. “Some humans do better at binary decisions like ‘a little now or a lot later’ than others. When psychologists study kids who are good at waiting for a reward, they find those kids generallly do better in life. It looks as though this is a key to success in the modern world, so why is it so hard for us to accept delays? The answer may be because we evolved as foragers who encountered no penalties for taking resources impulsively.

“Also,” Stephens added, “the National Institute on Drug Abuse funds a lot of studies of impulsiveness. It seems to play a part in addiction. I think anything we can do to understand impulsivity is a plus.”

[Iriabor]

Thanks Gadrel. Très intéressant, surtout le second en ce qui me concerne.

“Animals, I think, come with a hardwired rule that says, ‘Don’t look too far in the future,’“ Stephens said. “Being impulsive works really well because after grabbing the food, they can forget it and go back to their original foraging behavior. That behavior can achieve high long-term gains even if it’s impulsive.”

The work may apply to humans, he said, because taking rewards without hesitation may have paid off for our foraging ancestors, as it does for blue jays and other foragers. Modern society forces us to make either-or decisions about delayed benefits such as education, investment and marriage; the impulsive rules that work well for foragers do more harm than good when applied in these situations.

“Impulsiveness is considered a big behavior problem for humans,” said Stephens. “Some humans do better at binary decisions like ‘a little now or a lot later’ than others. When psychologists study kids who are good at waiting for a reward, they find those kids generallly do better in life. It looks as though this is a key to success in the modern world, so why is it so hard for us to accept delays? The answer may be because we evolved as foragers who encountered no penalties for taking resources impulsively.

Le passage ci-dessus (que je résumerais grossièrement en : le fait de savoir comparer une récompense immédiate à une valorisation future est le propre de l'être humain) m'a tout de suite fait penser à une extraordianire citation que j'ai trouvée la semaine passée (le gras est de moi) :

The purpose of art is not the release of a momentary ejection of adrenaline but is, rather, the gradual, lifelong construction of a state of wonder and serenity. Through the ministrations of radio and phonograph, we are rapidly and quite properly learning to appreciate the elements of aesthetic narcissism - and I use that word in its best sense - and are awakening to the challenge that each man contemplatively create his own divinity. — Glenn Gould

--

NP : Kaipa, Keyholder (2003)