Extensive Imitation is Irrational and Harmful*
研究发现，理性要求人们模仿那些品味相似但信息不同的人，但模仿共同来源会导致信念相关，理性社会学习者必须考虑这种相关性，从而严格限制理性模仿。在大多数自然观察结构中，完全理性要求人们“反模仿”某些观察对象，且净模仿人数最多为一人。
Abstract Rationality leads people to imitate those with similar tastes but different information. But people who imitate common sources develop correlated beliefs, and rationality demands that later social learners take this correlation into account. This implies severe limits to rational imitation. We show that (i) in most natural observation structures besides the canonical single-file case, full rationality dictates that people must “anti-imitate” some of those they observe; and (ii) in every observation structure full rationality dictates that people imitate, on net, at most one person and are imitated by, on net, at most one person, over any set of interconnected players. We also show that in a very broad class of settings, any learning rule in which people regularly do imitate more than one person without anti-imitating others will lead to a positive probability of people converging to confident and wrong long-run beliefs.