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                                                ——额叶皮质可调节自私与公平之间的矛盾

    社会总体需倚赖社会个体进行相互规范：如果我们认为有人行为不公，我们便会说该人行为不端。这样的指责可控制人的自私行为，促进社会有序发展。

    但控制欺骗的欲望从何而来呢？一个经济学家和神经学家团队目前确认，脑内某一区域在其中具有关键作用。这一发现不但有助于人是如何协作问题的解答，更能启发人们理解经济学和某些精神疾病。

    发表在journal Science1网络版上的该发现指出，这一结果从一个有名的游戏——最后通牒中得来。游戏规则是给与其中一个游戏者（提议人）20瑞士法郎，并告知其拿出一部分给另外一名游戏者。其要求是，如果第二个游戏者（应答者）拒绝接受提议人的钱，那么每一个人都将不能获得其中任何一分钱。

    这一游戏非常有趣，原因在于它可检验我们惩罚自私行为的意愿和合理经济行为之间的矛盾。在该游戏的单局制中，最合理的决定便是接受分得的钱，不论其多寡。如果不接受的话，则双方都得不到钱。但游戏者经常认为，分得的钱太少无异于被侮辱般不公；大多数都选择惩罚提议人，而且如果分得的钱少于5瑞士法郎则拒绝接受。

    瑞士苏黎世大学的Daria Knoch和一个经济学家和神经学家团队现已表明，抑制大脑某一部分可促使应答者更愿意接受不公现象。

犯罪与惩罚

    前脑中最具优势的区域被称作背外侧额叶皮质，目前已知其参与“最后通牒”这样的游戏。Knoch的团队运用磁场来抑制这一皮质单位的功能。

    运用磁场后发现，玩家对钱多少是否公平的感知没有改变：应答者依旧认为如果提议人拿出少于一定数目的钱，那么他（她）是自私的。但他们却很少愿意惩罚这一不公。

    该团队推测，当皮质的这一部分正常工作时，其至少参与了促进公平的脑内过程，抑制获取钱多少的理性欲望。“这是一项了不起的工作”洛杉矶，加里福尼亚大学研究文化演变的Robert Boyd指出。“这表明超出许可的话收买了你。”

    荷兰Groningen大学的André Aleman作为该研究团队中的一员指出，这一发现同时支持了情绪在经济决策制定中具有重要作用这一理论。“这是尽人皆知的道理。”他说，“但目前流行的经济学理论却认为这是认知的结果” 。

Brain blast squelches the desire to punish
Frontal cortex referees the conflict between being selfish and fair.
Jim Giles
All societies rely on individuals to police each other: if we think someone is behaving unfairly, we say so. Such rebukes rein in selfish behaviour and provide social glue.

But where does the desire to stop the cheats come from? A team of economists and neuroscientists has now identified a brain region that seems to play a critical role. As well as shedding light on how we cooperate, researchers say the finding could have implications for our understanding of economics and mental disorders.

The finding, published online in the journal Science1, describes the results from an adaptation of a famous experiment called the ultimatum game. One participant in the game — the proposer — is given 20 Swiss francs and told to pick an amount to share with the other player. The catch is that if that second player — the responder — turns down the offer, then neither player gets any money.

The game is interesting because it tests the conflict between our willingness to punish selfish actions and rational economic behaviour. In a single round of the game, the most rational decision is to accept whatever is offered, because the alternative is to receive nothing at all. But players often view very low offers as insultingly unfair; most choose to punish the proposer and refuse the money if less than 5 Swiss francs is offered.

Daria Knoch of the University of Zurich in Switzerland and a team of neuroscientists and economists have now shown that inhibiting part of the brain can make a responder more likely to accept unfair offers.

Crime and punishment

The righthand part of a region towards the front of the brain called the dorsolateral prefrontal cortex is already known to be involved in processes such as those that guide the ultimatum game (see 'Driven to market'). Knoch's team applied a magnetic field to this chunk of cortex in order to inhibit its functioning.

The players' perceptions of the fairness of offers were unchanged by this: the responders still thought the proposer was being selfish if he or she offered less than a certain number of Swiss francs. But they became less likely to inflict the punishment of rejection.

The team concludes that this part of the cortex, at least when it is working properly, is involved in brain systems that promote fairness and help smother the rational desire to take whatever is on offer.

"It's a terrific piece of work," says Robert Boyd of the University of California, Los Angeles, who studies the evolution of culture. "It shows what talking across disciplines buys you."

The finding also boosts the theory that emotions - in this case the desire for fairness — play an important role in economic decision-making, adds André Aleman, a neuroscientist at the University of Groningen in the Netherlands who is not part of the team. "It's common sense idea," he says. "But in economics the prevailing theory is that it's about cognitive decisions."

编辑：蓝色幻想