We study a canonical flexible-learning model in which an agent chooses from a finite set of alternatives, the benefits from which depend on a stochastic state. Before making her decision, the agent chooses what signal to acquire about this state. Learning comes at a cost, which the agent subtracts from the expected benefit she derives from her final decision. After choosing her information, the agent observes a signal realization and takes an action.

We model social media as collections of users producing and consuming content. Users value consuming content but due to scarce attention they may not value all content from other users. Users also value receiving attention, creating the incentive to attract an audience by producing valuable content but also through attention bartering—users mutually becoming each others’ audience. Attention bartering shapes substantially the patterns of production and consumption on social media, explains key features of social media behavior and platform decision-making, and yields sharp predictions that are consistent with data we collect from #EconTwitter. We conduct Twitter and Instagram user surveys that yield additional direct evidence in support of attention bartering, and we discuss the implications of attention bartering for the design of social media platforms.

A group of agents can collectively purchase a public good that yields heterogeneous benefits to its members. Combining a reduced-form implementation result with a duality argument, we characterize the seller's profit-maximizing mechanism. Trade outcomes depend solely on a weighted average of the agents' virtual values, with endogenous voting weights. Heterogeneity in voting weights reflects heterogeneity in agents' value distributions, where agents with lower value distributions are given more weight in trade decisions. Simple pricing rules are generally not (even approximately) optimal.