Rigidity and Flexibility of Social Systems-Further Research

等级制度，如政府和公司，如何应对变化？这些系统是否有对环境反应迟钝的趋势？决定这种制度僵化的因素是什么？为了解决这些问题，本项目将社会系统表示为一组有序的层次。在每一层都有一群代理，与代理相关联的是一个行为规则。在每个阶段，智能体观察随机环境的实现，并根据自己的规则选择行动。两种动力学决定了系统中代理部署的规则。首先，一个选择（或晋升）的动态决定代理人前进到更高的层次结构，从而影响人口的高层次的规则组合。第二，社会学习动态决定了代理人进入系统时所采用的规则。新的代理人试图模仿高级（即成功的）代理人，试图从他们的历史记录中推断出他们使用的规则。这两种动力学描述了一个定义在行为规则空间上的反馈系统：高级代理的历史决定了新代理所采用的规则，然后选择对这个队列进行操作，以产生一组新的高级代理，这些代理影响下一代新代理。在NSF资助9708910下进行的分析表征了一组动态稳定的结果，并探讨了它们对内部结构（例如，层次结构中的级别数）和外部结构（例如，环境的波动性）的依赖性。 最初，进化发生的行为规则空间包括对环境反应不同的规则。在当前的项目中，空间被重新定义，以允许规则在它们所响应的内容上有所不同。其中一条规则--个体学习规则--让智能体根据自己的（噪声）环境信号选择最佳行动。第二条规则--社会学习规则--让一个智能体选择大多数智能体在前一阶段选择的行动。当大多数代理人使用社会学习规则时，组织惰性可能会出现。对先前工作的第二个修改是将“表现良好”的含义内生化。“在公司的背景下，代理人的晋升不是基于某种固定的和外生的业绩概念（如利润），而是基于高级代理人的主观评价。如果根据他们的特质，不同的代理人以不同的方式解释绩效，那么绩效本身就是内生的，因为高级代理人的特质是过去选择的产物。本研究体现了这一特点的选择过程中提供了一个更丰富的描述动态等级社会。

How do hierarchical systems, such as governments and corporations, respond to change? Is there a tendency for such systems to become unresponsive to their envi-ronment? What are the factors determining the rigidity of such systems? To address these questions, this project represents a social system as a set of ordered levels. At each level is a population of agents and associated with an agent is a behavioral rule. In each period, agents observe the realization of a stochastic environment and choose an ac-tion according to their rule. Two dynamics determine the rules deployed by agents in the system. First, a selection (or promotion) dynamic determines which agents advance to higher levels in the hierarchy and thus affects the population mix of rules at high levels. Second, a social learning dynamic determines the rules that agents adopt when they enter the system. New agents seek to imitate high-ranking (that is, successful) agents by trying to infer the rule they used from their historical record. These two dynamics describe a feedback system defined on the space of behavioral rules: the history of high-ranking agents determines the rules adopted by new agents, selection then operates on this cohort to generate a new set of high-ranking agents who influences the next generation of new agents. Analysis conducted under NSF grant 9708910 characterized the set of dynamically stable outcomes and explored their dependence on features of the internal structure (for example, the number of levels in the hierarchy) and the external structure (for example, the volatility of the environment). Initially, the space of behavioral rules over which evolution took place included rules that differed in their responsiveness to the environment. In the current project, the space is redefined to allow rules to differ in what they are responsive to. One rule - the individual learning rule - has an agent choose that action which is best based upon their own (noisy) signal of the environment. A second rule - the social learning rule - has an agent choose that action that most agents chose in the previous period. Organizational inertia might then emerge when most agents use a social learning rule.A second modification of previous work is to endogenize what it means to "perform well." In the context of a corporation, agents do not advance based on some fixed and exogenous notion of performance (such as profit) but rather on the subjective evaluation of higher-ranking agents. If, depending on their traits, different agents interpret performance in different ways then performance is itself endogenous as the traits of higher-level agents are the product of past selection. This research embodies this feature of the selection process to provide a richer description of dynamics within a hierarchical society.