Ambiguous Persuasion: An Ex-Ante Formulation

TL;DR

This paper investigates a persuasion game with ambiguity-averse players, showing that ambiguity in information structures generally does not benefit the sender under ex-ante commitment, except when the sender has non-MEU preferences.

Contribution

It introduces an ex-ante formulation of ambiguity in persuasion games and demonstrates the limited benefits of ambiguous information structures for the sender.

Findings

Ambiguous information structures are not strictly beneficial for the sender.

Robustness of results to heterogeneous beliefs and non-MEU receiver preferences.

The sender's non-MEU preferences can make ambiguity advantageous.

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) the players having heterogeneous 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.