社会性网络解释观点的演化

Computer model hints at how opinions evolve

A computer model of the way opinions evolve in social networks has shown why two groups holding opposing views can quickly become reconciled or remain at odds.

The key, say European researchers, is how strongly the groups communicate with each other. The work could explain how language differences persist across geographic boundaries and how political thought can quickly become polarized.

To model the evolution of opinions, researchers led by physicist Renaud Lambiotte of the University of Liege in Belgium imagined two groups, initially isolated, whose members gradually begin to talk to members of the other group.

They supposed for simplicity that individuals hold one of two opinions, assigned randomly at the start. People then change their views by a “majority rule” – each person tends to adopt the opinion that is held by a majority of those with whom they are linked in the social network.

Solving their model mathematically, the authors found that when the two groups were isolated or nearly isolated, people within each group quickly came to share one opinion but the groups were as likely to agree as disagree with each other.

Tipping point

As Lambiotte and colleagues began adding social links between the groups. But they found no change, at first. The two groups continued to form opinions independently.

But rather than a gradual increase in the way opinions “leak” from one group to the other as more connections are added, the researchers found a surprise when the number of links between the groups reached a precise threshold. Suddenly, the final opinions of the two groups were always identical. Even a few extra links between groups were enough to “tip” their final opinions from a state of full polarization to full agreement.

“We didn’t expect such an abrupt transition,” says Lambiotte. “It implies that even a small change in network structure can lead to drastic consequences.”

Political poles

Lambiotte and colleagues suggest the results may help to explain why polarized communities can suddenly emerge rather than gradually appear. In the US, for example, researchers have noted an extreme and persisting polarization among bloggers expressing either Democratic or Republican political views. If most bloggers tend to read only those who agree with them, Lambiotte points out, groups associated with these differing positions can easily persist.

The work may also help explain why languages remain distinct across geographic borders rather than merging into a common tongue. The researchers argue that the same dynamic may preserve differences across boundaries where communications links are weak.

It may also help to account for the existence of small communities who use products different from the majority, such as Mac users in the graphic arts, Lambiotte suggests. But the model hints that the existence of these communities may be tenuous because even a small amount of interconnection could lead to their blending back into the majority.

The researchers hope to make more realistic models in the future, going beyond binary opinions and the strict majority rule. “There are still plenty of open questions,” says Marcel Ausloos, Lambiotte’s colleague at the University of Liege. “But we think the basic process is likely to remain the same.”

以下是参考译文（根据材料0605 40631143的翻译修改而成）：

社会性网络解释观点的演化

为何持对立观点的两群人可以在短时间内意见统一或依然保持分立？一个基于观点在社会性网络中演化的计算机模型解释了其中的原因。

欧洲研究人员称，这里的关键是人群间交流的强度。这项成果可以解释语言差异是如何由地理界线而保持的，以及政治思想是如何在短时间内变得两极分立。

为了模拟观念的转变过程，由比利时国王大学（the University of Liege）物理学家Renaud Lambiotte领导的研究人员设想了最初相互隔离的两群人，其中的成员逐渐地开始进行和另一群成员的交流。

为了简化实验，他们假设每人起初均随机地被指定持两种观点之一。接下来人们按一个“多数决定原则”交换意见——每人都倾向于接受他们在社交网络中接触的人们中多数人的意见。

用数学方法分析模型时，研究人员发现当两群人是隔离的或近乎隔离时，每群人会很快地持有共同的观点，但是两组之间观点的一致与否却不一定。

临界点

随后Lambiotte及其同事开始在两群人之间增加社交联系。起初，他们并没有发生变化，这两群人依然互相独立地形成观点。

但令研究人员惊讶的是，两群人的观点并未随着其间联系的增多（观点的渗透）而逐渐趋同，而是在最终联系的数量达到某一特定的极限后，突然达成共识。甚至仅在两组间增加几个联系就足以将他们的最终观点由完全分立的状态颠覆至完全统一。

Lambiotte称：“我们没料到会有如此突然的转变。这表明社交网络中哪怕很小的改变都能得到极其不同的结果。”

政治民意

Lambiotte及其同事认为这一结果可以解释对立的政体为何能突然产生而非逐渐出现的原因。以美国为例，研究者们注意到网志作者们中代表民主党 或共和 党观点的极端、持续两极对立的现象。Lambiotte指出，如果大多数网志作者倾向于仅阅读与其观点相同的文章时，与此两种不同观点相关的群体很容易持 续存在下去。

此项成果还可以解释为何在地理边缘的两侧语言可以保持截然不同的状态而非融为相同的语言。研究者们推断，同样的原因可以使交流沟通较弱的地区边界两侧保持差异。

Lambiott指出这项研究还有助于解释那些与大多数人使用不同物品的小团体的存在，比如创意工作者中Mac（苹果电脑）的使用者。但模型也揭示，这类团体的存在可能是十分脆弱的，因为仅仅很少的相互联系就能导致他们融合到大多数中去。

研究人员希望能在将来作出超越二元观点和严格“少数服从多数原则”的更加具有现实意义的模型。“仍有许多悬而未决的问题，”Lambiotte在国王大学的同事Marcel Ausloos说，“但我们认为基本的研究步骤将保持不变。”