We analyze a principal-agent procurement problem in which the principal (she) is unaware some of the marginal cost types of the agent (he). Communication arises naturally as some types of the agent may have an incentive to raise the principal's awareness (totally or partially) before a contract menu is offered. The resulting menu must not only reflect the principal's change in awareness, but also her learning about types from the agent's decision to raise her awareness in the first place. We capture this reasoning in a discrete concave model via a rationalizability procedure in which marginal beliefs over types are restricted to log-concavity, ``reverse'' Bayesianism, and mild assumptions of caution. We show that if the principal is ex ante only unaware of high-cost types, all of these types have an incentive raise her awareness of them -- otherwise, they would not be served. With three types, the two lower-cost types that the principal is initially aware of also want to raise her awareness of the high-cost type: Their quantities suffer no additional distortions and they both earn an extra information rent. Intuitively, the presence of an even higher cost type makes the original two look better. With more than three types, we show that this intuition may break down for types of whom the principal is initially aware of so that raising the principal's awareness could cease to be profitable for those types. When the principal is ex ante only unaware of more efficient (low-cost) types, then \textit{no type} raises her awareness, leaving her none the wiser.

翻译：我们分析了一个委托-代理采购问题，其中委托人（她）未意识到代理人（他）的部分边际成本类型。沟通自然产生，因为某些类型的代理人可能在合同菜单提供前有动机提高委托人的意识（完全或部分）。由此产生的菜单不仅必须反映委托人意识的变化，还必须反映她从代理人首先决定提高其意识的行为中对类型的学习。我们通过一个理性化程序在离散凹模型中捕捉这一推理过程，其中对类型的边际信念受限于对数凹性、“逆向”贝叶斯主义以及谨慎的温和假设。我们证明，如果委托人先验仅未意识到高成本类型，所有这些类型都有动机提高委托人对它们的意识——否则，它们将无法获得服务。在三种类型的情况下，委托人最初意识到的两种较低成本类型也希望通过提高委托人对高成本类型的意识：它们的数量不会受到额外扭曲，并且两者都能获得额外的信息租金。直观上，存在一个更高成本类型使得原有的两种类型看起来更好。当类型超过三种时，我们证明这种直觉对于委托人最初意识到的类型可能失效，因此提高委托人的意识对这些类型可能不再有利可图。当委托人先验仅未意识到更高效（低成本）类型时，则\textit{没有任何类型}会提高她的意识，使她一无所获。