EXTENSIVE IMITATION IS IRRATIONAL AND HARMFUL

• 成果类型: Article
• 署名作者: Eyster, Erik; Rabin, Matthew
• 署名单位: University of London; London School Economics & Political Science; Harvard University
• 刊物名称: QUARTERLY JOURNAL OF ECONOMICS
• ISSN/ISSBN: 0033-5533
• DOI: 10.1093/qje/qju021
• 发表日期: 2014
• 页码: 1861-1898
• 关键词: Herd behavior; Informational cascades; social networks

摘要

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.