2006/02/25 经济学俱乐部
| 美国《商业周刊》2005年3月28日 最近，在美国，一个由经济学家、心理学家和神经科学家组成的研究团队创建了一门新学科——“神经经济学”(neuroeconomics)；其要旨是通过“功能性磁共振成像”技术，观察人脑的深层状态。研究发现，人们之所以会在经济行为中产生非理性决策，与人脑的神经生理结构相关。 神经经济学对经济学的贡献在于，它放弃了主流经济学用以解释人类行为的各种过分简单的模型，在切实了解人脑精神活动的真实方式的基础上，重建经济学对经济行为的解释。 20世纪以来的主流经济学始终坚持“理性人”假设，认为人类具有稳定而持续的偏好，人们据此作出各种理性的行为决策。在这一框架下，所有明显不合逻辑的非理性行为，也被解释为某种理性决策过程的结果。 但神经经济学研究发现，当人们对长期行为进行决策时，他们的决策行为的确符合经济学教科书假定的“理性决策”过程。 而面对短期决策，比如是否立刻进行消费活动时，非理性冲动因素在人脑决策中的作用与猩猩毫无二致。 磁共振扫描发现，参与长期决策的主要是大脑额叶前区部分，理性思维主要是在人脑的这一部分进行。而在短期决策时，大脑边缘皮层的作用则会超过额叶前区，这时产生的决策更倾向于立即满足需要的原始状态。 在谈判的情境下，谈判者大脑中并非只有额叶前区皮层处于活跃状态，大脑皮层深处产生情绪反应的区域同时也被激活。当人们感到受到不公正待遇时，大脑中名为“前脑岛”的部分即被激活，产生强烈的情绪波动，其强度会超过额叶前区皮层产生的理性思维。 既然这种初级大脑活动如此强大，由此就不难解释为什么经济行为总是会走样。“在某种意义上，人类的经济行为就像猴子开汽车。”加州理工学院经济学家柯林说。 ==================================================== 《经济学家》杂志上最近有一篇文章"Mind games"，讨论了"神经经济学"(neuroeconomics)，一门通过对神经科学的研究来发现人的大脑如何进行经济决策。 文章说传统经济学认为对于是进行储蓄还是投资这样的决策，人被假设成完全考虑自身利益的冷酷的计算器（即理性人）。但是近几年来心理学的研究使得许多经济学家相信这个假设并不一定成立。如今一个新兴的领域，神经经济学试图通过解读人类的大脑来阐述人的经济行为的理性与感性的实质，以期预测社会经济。文章全文如下： Can studying the human brain revolutionise economics? ALTHOUGH Plato compared the human soul to a chariot pulled by the two horses of reason and emotion, modern economics has mostly been a one-horse show. It has been obsessed with reason. In decisions from how much to produce to whether to save and invest, humans have been assumed to be coolly rational calculators of their own self-interest. Over the past few years, however, evidence from psychology has persuaded many economists that reason does not always have its way. Now, judging from a series of presentations at the American Economic Association meetings in Philadelphia last weekend, a burgeoning new field dubbed "neuroeconomics" seems poised to provide fresh insights on how the two horses together produce economic behaviour. The current bout of research is made possible by the arrival of new technologies such as functional magnetic-resonance imaging, which allows second-by-second observation of brain activity. At several American universities, economists and their collaborators in the neurosciences have been placing human subjects in such brain scanners and asking them to perform a variety of economic tasks and games. For example, the idea that humans compute the "expected value" of future events is central to many economic models. Whether people will invest in shares or buy insurance depends on how they estimate the odds of future events weighted by the gains and losses in each case. Your pension, for example, might have a very low expected value if there is a large probability that bonds and shares will plunge just before you retire. Brian Knutson, of Stanford University, carried out one recent brain-scan experiment to understand how humans compute such things. Subjects were asked to perform a task, in this case pressing a button during a short interval in which a certain shape was flashed on to a screen. In some trials, the subjects could win up to $5 if successful, while in others they would have to defend against a $5 loss. Before presenting the target, the researchers signalled to subjects which kind of trial they were in. Brain activity in certain neural systems seemed to reveal a strong correlation with the amount of money at stake. Moreover, the prospects of gains and losses activated different parts of the brain. Traditional economists had long thought—or assumed—that the prospect of a $1,000 gain could compensate you for an equally likely loss of the same size. In subsequent trials, subjects were given another signal: one that provided an estimate of the odds of success. That allowed the researchers to identify the regions of the brain used for recognising an amount of money and for estimating the probability of winning (or losing) it. Having identified these regions, the hope is that future work can measure how the brain performs in situations such as share selection, gambling or deciding to participate in a pension scheme. David Laibson, an economist at Harvard University, thinks that such experiments underscore the big role that expectations play in a person's well-being. Economists have usually assumed that people's well-being, or "utility", depends on their level of consumption, but it might be that changes in consumption, especially unexpected downward ones, as in these experiments, can be especially unpleasant. Mr Laibson's own work tries to solve a different riddle: why people seem to apply vastly different discount rates to immediate and short-term rewards compared with rewards occurring well into the future. People tend much to prefer, say, $100 now to $115 next week, but they are indifferent between $100 a year from now and $115 in a year and a week. In one recent experiment, noted in our science section on October 30th, Mr Laibson and others found that the brain's response to short-term riches (in this case, gift certificates of $15 or $20) occurs largely in the limbic system, a region that governs emotion. By contrast, the prospect of rewards farther into the future triggers the prefrontal cortex, which is often associated with reason and calculation. Thus, choosing immediate economic gratification, by spending excessively on credit cards or not saving enough even though you "know better", could be a sign that the limbic system is in charge. Government policies, such as forced savings or "cooling off" periods for buying property or cars, may be one remedy. And then there is trust and deception. Colin Camerer, of the California Institute of Technology, has conducted experiments in which brain-scanned participants play strategic games with anonymous partners. In these, a subject chooses his own actions and also tries to anticipate the choices of the other player. When players are doing the best that they can to "win" the game by anticipating their opponents' moves, their brains tend to show a high degree of co-ordination between the "thinking" and the "feeling" regions. Economic equilibrium, by this measure, is an identifiable "state of mind". Don't let it go to your head Some neuroeconomists claim that such brain-scanning experiments are the start of a revolution in economics. No longer will economists rely on crude statistical models of how people behave in response to a policy change, such as an interest-rate rise or a tax increase. Instead, they will be able to peer directly into the brain to predict behaviour. One day, perhaps; but much work remains. Identifying the parts of the brain that control economic actions is one thing. Harder tasks include determining how neural systems work together to create behaviour, and how wide is the variation in brain patterns between different people. Then there are age-old questions of free will: is your failure to save for old age simply a lifestyle choice, or is it down to faulty brain circuits? Neuroeconomics is already providing fascinating conclusions. But Plato's chariot will remain an alluring explanation for a while yet. 又，维基百科对于神经经济学的解释是 Neuroeconomics combines neuroscience, economics, and psychology to study how we make choices. It looks at the role of the brain when you evaluate decisions, categorize risks and rewards, and interact with other people. ===================================== 实验经济学案例:神经经济学 让我们先做一个有关“信任”的游戏。我给你10英镑，你有两种选择，一是保留；二是送给一个你可能永远不再见到的匿名人士，如果运气好的话，他会还你15英镑，但也有可能他一分也不会还你。如果选择后者，给你的钱会扩大4倍至40英镑。你会如何抉择？ 当实验经济学家在实验室进行这一游戏时，一半测试对象决定把10英镑送出去，结果是3/4的受款人将钱送了回来。经济学家面临的难题是———找到人们这么做的原因，而这也是为什么如今越来越多的经济学家把目光投向大脑内部的原因。 因为在实验经济学方面开创性的成就，乔治梅森大学的弗农•史密斯获得了2002年诺贝尔经济学奖，最近，他对神经经济学产生了兴趣，通过扫描分析经济学游戏中实验对象的大脑，为实验经济学开辟了新的研究视角。“我们不知道这是否可行，但我们开始了一系列更为积极大胆的神经经济学实验，”史密斯教授如是说。 神经经济学正在吸引越来越多的研究者。9月中旬，经济学家和神经学家们就济济一堂，出席在美国举行的2003年神经经济学大会，这是致力探讨这一崭新课题的首批会议之一。大会发言者之一、来自克莱蒙大学的保罗•扎克解释了这一新研究背后的动机：“我们做过实验，发现人们的行为系统性地偏离了博弈的理论均衡，我们想弄懂为什么会出现那样的情况，于是，我们开始对神经过程进行研究。” 史密斯教授在“信任游戏”中所做的正是这些工作。对于游戏中实验对象的行为，一种可能是，他们没有正确理解游戏规则。另一个可能的解释是，他们非常理解游戏规则，但其它一些比理性更强大的精神活动过程在起作用。 史密斯教授表示：“在日常生活中，很多人习惯于彼此交换好处，如果你无意中发现别人给了你好处，那你马上就会有这么个问题：做出回报还是占人家便宜？”这种想法似乎挺有道理，但并不容易测试。于是在游戏中，史密斯教授的研究小组使用磁共振功能成像技术对测试对象的大脑进行扫描。扫描结果显示，与他人合作的测试对象使用了大脑中称作布罗德曼8区和10区的部分。以前的研究表明，这些区域涉及人们对精神活动的思考、对其他人动机的思考，也与延迟满足感以接收随后更高的回报有关。不与他人合作的测试对象则没有使用上述大脑区域。史密斯教授指出，这一结果与“互惠交换”的解释是一致的：游戏参与者考虑了其他参与者的反应并决定信任他们。 脑部扫描并不是神经经济学家们的唯一工具。他们还有包括测量脉搏速度、皮肤传导性及荷尔蒙水平等其它方法。作为此类实验的结果，神经经济学家们获得了各种发现成果，其中之一是排卵期妇女的可信度比其他人要低。 但并不是没有人对此持怀疑态度。埃姆瑞大学教授格雷格•伯恩斯是2003年神经经济学大会的组织者，他承认批评意见的存在，他表示：“对于这项研究会否产生任何伟大的创见，现在断言还为时尚早。” 现在下结论或许是早了点，但企业家的行动看起来更早，他们似乎已经触摸到了这项技术所能带来的商机。总部位于亚特兰大的一家咨询公司———Brighthouse已经成立了“神经营销”部门，运用磁共振功能成像扫描技术也列入了该公司的市场营销手段。在近期完成的一个测试项目中，科学家一边向测试对象展示图片，一边对他们当时的大脑活动进行扫描，而在此之前，测试对象已对这些产品、人物或活动的图片表明了偏好程度。公司研究员贾斯廷•莫说：“我们观察到的是，人们在面对偏好程度不同的事物时，大脑活动的模式有质的区别。”虽然公司不愿向外界透露更多的研究结果信息，但莫女士称：“神经营销有着独特的地位，它能让企业从一个新的视角去审视，与客户紧密相连究竟意味着什么。” 为“粘住”消费者，营销商和广告商可谓无孔不入，现在他们又有新的“武器”了———用神经经济学“窥视”我们的大脑，他们很有可能获得成功。明尼苏达大学的约翰•迪克豪特认为，神经经济学将提供一种理论，解释人们何时以及为何会出现非理性行为。 神经经济学领域的其他研究人员也同样希望，神经经济学能用在对社会有利的方面。伯恩斯教授就想闯入神经经济学中更深奥的领域，“我希望，通过研究大脑，我们将对‘幸福’有更好的理解，也能更好理解人们为何对现状如此不满。”如果他能在这项研究上取得突破，那么神经经济学真的会让经济学发生翻天覆地的变化。 引用自 : http://166.111.106.5:8080/xi-suo/jjs/econ/Article_Show.asp?ArticleID=830 |
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