从众行为与创新扩散：基于信息成本角度的研究

地方政府跟风上马新兴产业、投资者股市跟风盲从等从众行为经常出现，但同时地方政府的大量政策创新却鲜少得到推广。针对这两类看似相反的现象，本课题探索信息成本如何影响从众行为的发生以及探索从众环境下以改变信息成本为主要手段的最优经济政策干预。其所依赖的经济学直觉在于：当观察他人行为的成本为零时，观察到多个他人的相同行为容易使得决策人忽略自有信息采取从众决定，从而造成分散在众人中的大部分信息难以传递；当该成本很高时，决策人会失去获取他人行为中所隐藏信息的机会，从而造成分散在众人中的信息无法传递。子课题1和2分别从理论和实验方面探索信息成本及其相关政策干预对有限理性人从众行为和福利水平的影响。子课题3从实证方面探索地方政府创新较少扩散的信息成本解释。本项目科学问题的解决将不仅带来包括建立有限理性人从众行为及其福利经济理论在内的重要理论突破，而且对促进地方政府创新扩散这一重大现实关切具有重要应用价值。

On the one hand, we often observe herd behavior such as local governments' developing rising industries and investors' following suit in stock markets. On the other hand, we rarely see the diffusion of local government policy innovations. Inspired by the two classes of seemingly opposite phenomena, we investigate the impact of costly information acquisition on herd behavior and study the optimal policy intervention in social learning environments from the perspective of manipulating the cost of information acquisition. Our project bases itself on an economic intuition as follows. When perfectly observing predecessors' actions that are possibly identical, people may make an inference from predecessors' actions and then follow suit regardless of their own private information. Consequently, information held by the public can not be effectively disseminated and aggregated. When observing no predecessors' actions, especially in a scenario with a prohibitively high cost of information acquisition, people have to make choice decisions based only on their own private information and in turn there is no information dissemination at all. Formalizing the above intuition, subprojects 1 and 2 investigate theoretically and experimentally respectively the impact of costly information acquisition on the behavior and the welfare of bounded rational decision makers in social learning settings. Subproject 3 investigates the empirical evidence that costly information acquisition accounts for little diffusion of local government policy innovations. An answer to our research questions will not only make important theoretical contributions such as establishing a novel theory of herd behavior and the welfare analysis under the assumption of bounded rationality, but also have plenty of policy implications such as how to improve the diffusion of local government policy innovations.