A present-biased consumer has to make sequential consumption decisions under no commitment. Consumption is enjoyable in the short term but potentially harmful in the long term. The likelihood of harmful future consequences hinges on the consumer's type. While the distribution of types is common knowledge, the consumer's individual type is initially unknown. We study information design in this setting, varying how much a consumer learns about his type via an information nudge. We first consider a mechanism designer who is benevolent in the sense that his interests are aligned with the consumer's. We find that there always exists an optimal incentive-compatible persuasion mechanism that is of cutoff type, either recommending consumption or abstinence, and we provide a full characterization of this information nudge for an arbitrary distribution of types. Under a stronger bias for the present, the target group of the nudge who receives a credible signal to abstain must be tightened. We compare this information nudge with the optimal information structure if expected consumption should be minimized, and if it should be maximized. The first may be the goal of a health authority, whereas the latter may be preferred by a lobbyist.
Information Design; Information Nudge; Present-Biased Preferences; SelfControl;
- C73: Stochastic and Dynamic Games • Evolutionary Games • Repeated Games
- D82: Asymmetric and Private Information • Mechanism Design
IAST working paper, n. 18-84, April 2018, revised November 2018