We study optimal direct mechanisms for a credence goods expert who can be altruistic or spiteful. The expert has private information about her distributional preferences and possibly also about her customer's needs. We introduce a method that allows the customer to offer separate contracts to...

A principal hires an agent to learn about the cost of a project (experimentation) and then to execute it (production). The agent is privately informed about the probability that the cost is low, with the high-type agent being relatively more optimistic than the low type. The agent also engages...