经济学人39:社会科学 关于群体的思考

 　　Science and Technolgy

　　科技

　　Social science

　　社会科学

　　Wisdom about crowds

　　关于群体的思考

　　To model the behaviour of humans en masse, treat them as people, not molecules¹

　　在为人类的全体活动建立模型时，要将他们看作是"人"，而不是"分子"。

　　THE behaviour of crowds is sometimes unpredictable and occasionally deadly, but there is good reason to believe it is governed by simple rules. Presumably, like molecules in a liquid, people in a crowd all behave in more or less the same way. Capture those similarities in a model and it should be possible to predict how a crowd will behave.

　　群体的行动有时候是不可知的，偶然致使的，不过有充分的理由相信，这种行为符合简单的规律。简单说来，这就像液体中的分子，在群体中的人的行动大致是一样的。在一个模型中捕获这些相似性可以对于一个群体的行动进行预测。

　　Existing models of crowd behaviour do just that. They treat moving masses of humanity as though they were fluids. This works, up to a point. But it often fails to predict the changes that happen as a crowd's density² increases and its movement becomes chaotic³. That is why Mehdi Moussaid of Paul Sabatier University, in Toulouse, and his colleagues have made a radical⁴ innovation. Instead of treating the individual human beings in a crowd as if they were molecules, they have treated them as if they were human beings. They have, in other words, given them volition⁵. Of course, the objective of someone in a moving crowd is usually fairly simple-to get somewhere and then stay there. But it is an objective, nevertheless.

　　现有的大众行动模型就可以做到这一点。这些模型将变化的人类群体当作是液体。在某种程度（或者条件）下，这个模型非常有效。不过当涉及到群体的密度增加，运行变得混乱时，对于预测发生的变化往往不能奏效。这就是保尔?萨巴蒂大学（Paul Sabatier University，在图卢兹）的迈赫迪?穆赛德（Mehdi Moussaid）和他的同事已经进行突破性创新的原因。与以往的理论中将群体看作是分子不同，他们将群体看作是"人"。换句话说，就是考虑到了"人的意志"。当然了，在一个活动的群体中的客观存在的一些人通常比较简单：到哪里，就待在那。即使这样，它还是一个客观存在的事物。

　　As they describe in the Proceedings⁶ of the National Academy of Sciences, Dr Moussaid and his team built a computer model in which, initially⁷, every virtual person in the crowd followed two rules. The first was that each attempted to chart as straight as possible a path to his destination, such as an exit or the end of a corridor, while avoiding obstacles, including other pedestrians⁸. Second, each adjusted his speed, depending on his distance from such obstacles.

　　就像他们在《美国国家科学院学报》中所描述的那样，穆赛德博士和他的团队建立了一个计算机模型，在这个模型里，起先，每个虚拟的在群体中的人都服从两个规律。第一，当避开包括其他行人在内的障碍时，每个人都试图尽量以直线的的路线到达目的地，就像一个出口或一个走廊的尽头。第二，每个人都会调整自己的速度，这个依赖于与障碍物的距离。

　　These two rules were enough to reproduce in the model the sorts of behaviour seen in real crowds, such as the tendency people have to sort themselves spontaneously into separate lanes of traffic moving in opposite directions and the stop-and-go motion that occurs as crowds become more dense⁹. When Dr Moussaid really put the pressure on, however, by increasing the density of the virtual crowd, the model did not show the extreme turbulence¹⁰ seen in real crowds-the sudden crushes and chaotic changes in direction.

　　这两个规则在真实的群体中的各种行为上已经得到了足够的验证，例如，在公路上，人们通常会趋向于同时将自己朝相反的方向移动，这种停停走走的行为，让本来发生的拥挤更加拥挤。当穆赛德博士确实增加压力时——通过增加虚拟人群的密度，在真实的人群中，这个模型并没有显示出的骚乱——骤然的碾压和方向变化的混乱。

　　These happen because in extremely dense crowds there is so much shoving and jostling that people's movements are no longer entirely¹¹ under their own control. In other words, they actually do start behaving like molecules in a fluid, bouncing off one another at random¹². To mimic¹³ that behaviour, Dr Moussaid added a third rule, which made members of his crowd more molecule-like when they were at very close quarters-a lack of volition that will be familiar to anyone who has been in a tight jam of humanity.

　　因为在极其密集的人群里，有很多人推搡和拥挤，人们自身的行动并不受自己的控制，因此会发生混乱。换句话说，这个时候，他们就像液体中的分子一样，被任意地反弹。为了模拟这种行为，穆赛德博士又增加了第三条规律，即当群体中的成员之间非常接近的时候，他们就像分子一样，此时群体中的成员是缺乏意志的，对那些处于拥挤人群里的人来说，这种感觉深有体会。

　　With this third rule added, the model accurately¹⁴ reproduced the dynamics¹⁵ of dense crowds as well as those of sparser¹⁶ ones. At first, a crowd flows smoothly¹⁷. Then, as more people are added, it begins to show stop-and-go patterns and sometimes extreme crushing. Finally, it displays the sort of turbulence that can lead to disaster. On one run, for example, the model showed precisely¹⁸ the pattern seen in a video of a catastrophe¹⁹ in Mecca in 2006, when 346 pilgrims there on the haj were crushed to death.

　　有了这第三条规律的补充，无论在动态密集的人群里还是在稀疏的人群里，这种模型都会精确在得到再现。最初，人群流动顺畅。接着，更多的人加入，整个人群开始变成时走时停的模型，有时候还变得极度拥挤。最后，人群变得混乱，并能导致灾难。例如，在2006年麦加的朝觐的灾难上，根据视频的显示内容，这种模型得到了精确的显示，当时有346名朝圣者在混乱中被踩踏至死。

　　The practical upshot of all this, Dr Moussaid hopes, will be improvements in the design of public spaces where crowds are likely to gather, especially in the location of evacuation routes. That is an outcome greatly to be desired. And it was made possible by remembering that people are not molecules.

　　穆赛德博士希望，所以有这种真实的结果会对有助于改善公共场所的设计，尤其是对于疏散通道位置的考虑，在这种场合下，有可能聚集大量的人。这是一个非常值得注意的结果。一定要牢记，人，不是分子。

1 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

2 density   

n.密集，密度，浓度

参考例句：

• The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
• The region has a very high population density.该地区的人口密度很高。

3 chaotic   

adj.混沌的，一片混乱的，一团糟的

参考例句：

• Things have been getting chaotic in the office recently.最近办公室的情况越来越乱了。
• The traffic in the city was chaotic.这城市的交通糟透了。

4 radical   

n.激进份子，原子团，根号；adj.根本的，激进的，彻底的

参考例句：

• The patient got a radical cure in the hospital.病人在医院得到了根治。
• She is radical in her demands.她的要求十分偏激。

5 volition   

n.意志；决意

参考例句：

• We like to think that everything we do and everything we think is a product of our volition.我们常常认为我们所做和所想的一切都出自自己的意愿。
• Makin said Mr Coombes had gone to the police of his own volition.梅金说库姆斯先生是主动去投案的。

6 proceedings   

n.进程，过程，议程；诉讼(程序)；公报

参考例句：

• He was released on bail pending committal proceedings. 他交保获释正在候审。
• to initiate legal proceedings against sb 对某人提起诉讼

7 initially   

adv.最初，开始

参考例句：

• The ban was initially opposed by the US.这一禁令首先遭到美国的反对。
• Feathers initially developed from insect scales.羽毛最初由昆虫的翅瓣演化而来。

8 pedestrians   

n.步行者( pedestrian的名词复数 )

参考例句：

• Several pedestrians had come to grief on the icy pavement. 几个行人在结冰的人行道上滑倒了。 来自《简明英汉词典》
• Pedestrians keep to the sidewalk [footpath]! 行人走便道。 来自《现代汉英综合大词典》

9 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。

10 turbulence   

n.喧嚣，狂暴，骚乱，湍流

参考例句：

• The turbulence caused the plane to turn over.空气的激流导致飞机翻转。
• The world advances amidst turbulence.世界在动荡中前进。

11 entirely   

ad.全部地，完整地；完全地，彻底地

参考例句：

• The fire was entirely caused by their neglect of duty. 那场火灾完全是由于他们失职而引起的。
• His life was entirely given up to the educational work. 他的一生统统献给了教育工作。

12 random   

adj.随机的；任意的；n.偶然的(或随便的)行动

参考例句：

• The list is arranged in a random order.名单排列不分先后。
• On random inspection the meat was found to be bad.经抽查，发现肉变质了。

13 mimic   

v.模仿，戏弄；n.模仿他人言行的人

参考例句：

• A parrot can mimic a person's voice.鹦鹉能学人的声音。
• He used to mimic speech peculiarities of another.他过去总是模仿别人讲话的特点。

14 accurately   

adv.准确地，精确地

参考例句：

• It is hard to hit the ball accurately.准确地击中球很难。
• Now scientists can forecast the weather accurately.现在科学家们能准确地预报天气。

15 dynamics   

n.力学，动力学，动力，原动力；动态

参考例句：

• In order to succeed,you must master complicated knowledge of dynamics.要取得胜利，你必须掌握很复杂的动力学知识。
• Dynamics is a discipline that cannot be mastered without extensive practice.动力学是一门不做大量习题就不能掌握的学科。

16 sparser   

adj.稀疏的，稀少的( sparse的比较级 )

参考例句：

17 smoothly   

adv.平滑地，顺利地，流利地，流畅地

参考例句：

• The workmen are very cooperative,so the work goes on smoothly.工人们十分合作，所以工作进展顺利。
• Just change one or two words and the sentence will read smoothly.这句话只要动一两个字就顺了。

18 precisely   

adv.恰好，正好，精确地，细致地

参考例句：

• It's precisely that sort of slick sales-talk that I mistrust.我不相信的正是那种油腔滑调的推销宣传。
• The man adjusted very precisely.那个人调得很准。

19 catastrophe   

n.大灾难，大祸

参考例句：

• I owe it to you that I survived the catastrophe.亏得你我才大难不死。
• This is a catastrophe beyond human control.这是一场人类无法控制的灾难。