We run an experiment to compare belief formation and learning under ambiguity and under compound risk at the individual level. We estimate a four-type mixture model assuming that, for each type of uncertainty, subjects may either learn according to Bayes’ Rule or learn according to a multiple priors model of learning. Our results indicate that majority of subjects are Bayesian, both under compound risk and under ambiguity, while the second most frequent type are subjects that are Bayesian under compound risk but who use a multiple priors model of learning under ambiguity. In addition, we find strong evidence against a common assumption that participants’ initial beliefs (and priors) are consistent with information provided about the uncertain process.

我们进行了一项实验，以在个体层面比较模糊和复合风险下的信念形成和学习。我们估计了一个四类混合模型，假设对于每种类型的不确定性，受试者要么根据贝叶斯规则学习，要么根据多先验学习模型学习。我们的结果表明，在复合风险和歧义下，大多数受试者都是贝叶斯式的，而第二常见的类型是在复合风险下是贝叶斯式的，但在歧义下使用多先验学习模型的受试者。此外，我们发现强有力的证据反对一个共同的假设，即参与者的初始信念（和先验）与提供的关于不确定过程的信息一致。