复杂传染

此词条暂由彩云小译翻译，未经人工整理和审校，带来阅读不便，请见谅。

}}

Complex contagion is the phenomenon in social networks in which multiple sources of exposure to an innovation are required before an individual adopts the change of behavior. It differs from simple contagion in that unlike a disease, it may not be possible for the innovation to spread after only one incident of contact with an infected neighbor. The spread of complex contagion across a network of people may depend on many social and economic factors; for instance, how many of one's friends adopt the new idea as well as how many of them cannot influence the individual, as well as their own disposition in embracing change.

Complex contagion is the phenomenon in social networks in which multiple sources of exposure to an innovation are required before an individual adopts the change of behavior. It differs from simple contagion in that unlike a disease, it may not be possible for the innovation to spread after only one incident of contact with an infected neighbor. The spread of complex contagion across a network of people may depend on many social and economic factors; for instance, how many of one's friends adopt the new idea as well as how many of them cannot influence the individual, as well as their own disposition in embracing change.

复杂传染是社会网络中的一种现象，在这种社会网络中，一个人在采取行为改变之前，需要有多个接触创新的渠道。它不同于简单的传染病，不同于疾病，创新不可能仅仅在与受感染的邻居发生一次接触后传播。复杂的传染病在一个人际网络中的传播可能取决于许多社会和经济因素; 例如，一个人的朋友中有多少人接受了新观念，有多少人不能影响个人，以及他们接受改变的倾向。

Mechanisms

Complex Contagion and the Weakness of Long Ties by Damon Centola of University of Pennsylvania and Michael Macy of Cornell University found that information and disease spread as “simple contagions”, requiring only one contact for transmission, while behaviors typically spread as “complex contagions”, requiring multiples sources of reinforcement to induce adoption. Centola’s work builds on Granovetter’s work on the strength of weak ties and threshold models of collective behavior, as well as Duncan Watts and Steve Strogatz’s work on small world networks. Centola and Macy show that the weak ties and small worlds networks are both very good for spreading simple contagions. However, for complex contagions, weak ties and small worlds can slow diffusion.

Complex Contagion and the Weakness of Long Ties by Damon Centola of University of Pennsylvania and Michael Macy of Cornell University found that information and disease spread as “simple contagions”, requiring only one contact for transmission, while behaviors typically spread as “complex contagions”, requiring multiples sources of reinforcement to induce adoption. Centola’s work builds on Granovetter’s work on the strength of weak ties and threshold models of collective behavior, as well as Duncan Watts and Steve Strogatz’s work on small world networks. Centola and Macy show that the weak ties and small worlds networks are both very good for spreading simple contagions. However, for complex contagions, weak ties and small worlds can slow diffusion.

宾夕法尼亚大学的 Damon Centola 和康奈尔大学的 Michael Macy 发现，信息和疾病的传播是简单的传染，只需要一个接触来传播，而行为通常以复杂传染的形式传播，需要多个来源的强化来诱导接受。的工作建立在 Granovetter 的弱关系的力量和集体行为的阈值模型的工作上，以及 Duncan Watts 和 Steve Strogatz 的小世界网络的工作上。和 Macy 指出弱关系和小世界网络都非常有利于传播简单传染。然而，对于复杂的传染，弱关系和小世界可以减缓扩散。

Centola and Macy suggest four mechanisms of complex contagion. These properties explain the need for multiple exposures in the spread of contagion:

Centola and Macy suggest four mechanisms of complex contagion. These properties explain the need for multiple exposures in the spread of contagion:

森托拉和梅西提出了四种复杂传染机制。这些特性解释了在传染蔓延过程中需要多重风险敞口的原因:

1. Strategic complementarity. Many innovations are costly, especially for early adopters but less so for those who wait. The same holds for participation in collective action.

Strategic complementarity. Many innovations are costly, especially for early adopters but less so for those who wait. The same holds for participation in collective action.

战略互补性。许多创新成本高昂，尤其是对于早期采用者，但对于那些等待的人来说成本较低。参与集体行动也是如此。

1. Credibility. Innovations often lack credibility until adopted by neighbors. Hearing the same story from different people makes it seem less likely that surprising information is nothing more than the fanciful invention of the informant.

Credibility. Innovations often lack credibility until adopted by neighbors. Hearing the same story from different people makes it seem less likely that surprising information is nothing more than the fanciful invention of the informant.

可信度。在被邻居采用之前，创新往往缺乏可信度。从不同的人那里听到同样的故事，使得令人惊讶的信息不过是线人幻想出来的东西的可能性降低了。

1. Legitimacy. Knowing that a movement exists or that a collective action will take place is rarely sufficient to induce bystanders to join in. Having several close friends participate in an event often greatly increases an individual’s likelihood of also joining, especially for high-risk social movements. Innovators risk being shunned as deviants until there is a critical mass of early adopters, and non-adopters are likely to challenge the legitimacy of the innovation.

Legitimacy. Knowing that a movement exists or that a collective action will take place is rarely sufficient to induce bystanders to join in. Having several close friends participate in an event often greatly increases an individual’s likelihood of also joining, especially for high-risk social movements. Innovators risk being shunned as deviants until there is a critical mass of early adopters, and non-adopters are likely to challenge the legitimacy of the innovation.

合法性。知道一个运动的存在或者一个集体行动将要发生并不足以吸引旁观者加入。有几个亲密的朋友参加一个活动通常会大大增加一个人加入的可能性，特别是对于高风险的社会运动。创新者冒着被当作异类而回避的风险，直到有足够数量的早期采用者，而非采用者可能会挑战创新的合法性。

1. Emotional contagion. Most theoretical models of collective behavior – from action theory to threshold models to cybernetics share the basic assumption that there are expressive and symbolic impulses in human behavior that can be communicated and amplified in spatially and socially concentrated gatherings.

Emotional contagion. Most theoretical models of collective behavior – from action theory to threshold models to cybernetics share the basic assumption that there are expressive and symbolic impulses in human behavior that can be communicated and amplified in spatially and socially concentrated gatherings.

情绪感染。大多数关于集体行为的理论模型——从行动理论到阈值模型到控制论——都有一个共同的基本假设，即人类行为中存在表达冲动和象征冲动，这些冲动可以在空间和社会集中的集会中得到沟通和放大。

Contested vs. uncontested

Uncontested

Uncontested

无争议的

The spread of the contagion is dependent solely on the number of people you are connected to who are different from your own state. You are not hindered whatsoever by the number of people in the same state as you. Generally, the more neighbors an individual has, the greater the chance of the individual adopting the innovation if the spread is uncontested.

The spread of the contagion is dependent solely on the number of people you are connected to who are different from your own state. You are not hindered whatsoever by the number of people in the same state as you. Generally, the more neighbors an individual has, the greater the chance of the individual adopting the innovation if the spread is uncontested.

传染的传播完全取决于与你有联系的人的数量，这些人与你所在的州不同。你不会因为和你处于同一状态的人的数量而受到任何阻碍。一般来说，一个人的邻居越多，如果创新的传播是无争议的，那么这个人采用创新的机会就越大。

Contested

Contested

竞逐

The spread of the contagion is dependent on both the adamancy of those who are in a different state from your own as well as the countervailing influence of those who share your current state. In this case, the more neighbors an individual has, the smaller the chance of the individual adopting the innovation.

The spread of the contagion is dependent on both the adamancy of those who are in a different state from your own as well as the countervailing influence of those who share your current state. In this case, the more neighbors an individual has, the smaller the chance of the individual adopting the innovation.

传染病的传播既取决于那些与你处于不同状态的人的坚强，也取决于那些与你处于同一状态的人的抵消性影响。在这种情况下，一个人的邻居越多，他采用创新的机会就越小。

Diffusion and cascading behaviors in networks

See also: Global cascades model

Consider a graph of any reasonable size. Node v’s neighbors can be split into two sets: Set A contains v's neighbors who have adopted a new behavior and B is the set of those behaving conservatively. Node v will only adopt the behavior of those in A if at least a q fraction of neighbors follow behavior A.

Consider a graph of any reasonable size. Node v’s neighbors can be split into two sets: Set A contains v's neighbors who have adopted a new behavior and B is the set of those behaving conservatively. Node v will only adopt the behavior of those in A if at least a q fraction of neighbors follow behavior A.

考虑一个合理大小的图表。节点 v 的邻居可以分成两组: 设置 a 包含已经采用新行为的 v 邻居，设置 b 是行为保守的邻居。如果至少有一部分邻居遵循行为 a，那么 Node v 只会采用 a 中的行为。

• if q is small, the behavior is easily adopted and easily spread

• if q is large, B is an attractive behavior and it takes more friends to engage in A before v will switch.

Cascading – diffusion over the entire network

Consider a set of initial adopters who start with a new behavior A, while every other node starts with behavior B. Nodes then repeatedly evaluate the decision to switch from B to A using a threshold of q. If the resulting cascade of adoptions of A eventually causes every node to switch from B to A, then we say that the set of initial adopters causes a complete cascade at threshold q. Clusters of density d > 1 − q are obstacles to cascades across the entire network.

Cascading – diffusion over the entire network : Consider a set of initial adopters who start with a new behavior A, while every other node starts with behavior B. Nodes then repeatedly evaluate the decision to switch from B to A using a threshold of q. If the resulting cascade of adoptions of A eventually causes every node to switch from B to A, then we say that the set of initial adopters causes a complete cascade at threshold q. Clusters of density d > 1 − q are obstacles to cascades across the entire network.

整个网络的级联扩散: 考虑一组以新行为 a 开始的初始采用者，而其他每个节点以行为 b 开始。然后使用 q 的阈值重复计算从 b 切换到 a 的决策。如果 a 的采用产生的级联最终导致每个节点从 b 切换到 a，那么我们说，初始采用者的集合在阈值 q 处导致了一个完整的级联。

Application and examples

Many of our interactions with the rest of the world happen at a local, rather than a global, level – we often don't care as much about the full population's decisions as about the decisions made by friends and colleagues. For example, in a work setting we may choose technology to be compatible with the people we directly collaborate with, rather than the universally most popular technology. Similarly, we may adopt political views that are aligned with those of our friends, even if they are nationally in the minority.

Many of our interactions with the rest of the world happen at a local, rather than a global, level – we often don't care as much about the full population's decisions as about the decisions made by friends and colleagues. For example, in a work setting we may choose technology to be compatible with the people we directly collaborate with, rather than the universally most popular technology. Similarly, we may adopt political views that are aligned with those of our friends, even if they are nationally in the minority.

我们与世界其他地方的许多互动发生在一个本地层面，而不是一个全球层面——我们往往不像关心朋友和同事的决定那样关心全体人民的决定。例如，在工作环境中，我们可能会选择与我们直接合作的人兼容的技术，而不是最普遍流行的技术。同样，我们可能采取与我们的朋友一致的政治观点，即使他们在全国范围内属于少数派。

Examples

• The credibility of an urban legend

• Willingness to participate in migration – (participating in a collective action)

• Incentives to exit formal gatherings

• What clothing to wear, hairstyle to adopt, and what part of the body to pierce.

Examples of simple contagion

• The spread of disease

• The spread of information

See also

• Emotional contagion

• Mark Granovetter

• Graph theory

References

}}

Category:Social networks

分类: 社交网络

This page was moved from wikipedia:en:Complex contagion. Its edit history can be viewed at 复杂传染/edithistory