题目：Small deeds reveal a man? On over-interpretation of uninformative social signals
Social signals contain information that helps to reveal one's social type. We study whether people over-interpret uninformative social signals and how this bias affects social decision-making. A model is presented which implies overreaction to small social signals and distinguishes between two sources of belief over-updating: a cognitive need to reduce perceived uncertainty and the self-serving belief to justify selfishness. We test these implications with a dictator-game experiment in which the dictator receives an essentially uninformative signal about the recipient before making an allocation. We find that dictators significantly react to the signal and that the cognitive-need explanation is favored.