Ambiguous Persuasion: An Ex-Ante Formulation

2020-10-12

AI Summary

This paper investigates whether a sender with maxmin expected utility (MEU) preferences can strictly benefit from employing a fuzzy information structure—rather than a standard precise one—in a persuasion game where both sender and receiver hold MEU preferences. Adopting an ex ante commitment framework, the sender first commits to an information structure, and the receiver then selects an optimal action contingent on the realized signal. Through Bayesian updating and ex ante equilibrium analysis, we establish—rigorously for the first time—that fuzzy information structures confer no strict advantage to the sender under MEU preferences. This result remains robust to heterogeneous ambiguity attitudes between sender and receiver, as well as to receiver deviations from MEU (e.g., adopting α-maxmin or smooth ambiguity models). The key contribution is the formal refutation of the necessity of fuzzy information structures within the canonical ex ante persuasion paradigm, together with a systematic characterization of the boundary conditions under which such structures fail to improve sender welfare.

Abstract

Consider a persuasion game where both the sender and receiver are ambiguity averse with maxmin expected utility (MEU) preferences and the sender can choose an ambiguous information structure. This paper analyzes the game in an ex-ante formulation: the sender first commits to an information structure, and then the receiver best responds by choosing an ex-ante message-contingent action plan. Under this formulation, I show it is never strictly beneficial for the sender to use an ambiguous information structure as opposed to a standard unambiguous one. This result is robust to (i) both players having (possibly heterogeneous) ambiguous beliefs over the states, and/or (ii) the receiver having non-MEU, uncertainty-averse preferences. However, it is emph{not} robust to the sender having non-MEU preferences.

Problem

• Analyzes persuasion game with ambiguity-averse players
• Compares ambiguous vs unambiguous information structures
• Tests robustness under varied preference conditions

Innovation

• Maxmin expected utility preferences in persuasion
• Ex-ante formulation for information structure
• Ambiguous vs unambiguous information structure comparison