Strategies of Deception: Under-Informativity, Uninformativity, and Lies-Misleading With Different Kinds of...

Conversation is often cast as a cooperative effort, and some aspects of it, such as implicatures, have been claimed to depend on an assumption of cooperation (Grice, 1989). But any systematic class of inference derived from assumptions of cooperation, such as implicatures, could also be, on occasion, used to deceive listeners strategically. Here, we explore the extent to which speakers might choose different kinds of implicature triggers in an uncooperative game of communication. Concretely, we present a study in the form of a cooperative or competitive signaling game where communicators can exploit three kinds of implicatures: exact reading of numeral expressions, scalar implicatures linked to the quantifier some and ad hoc scalar implicatures. We compare how these implicatures are used depending on whether the participants' co-player is cooperative, a strategic opponent, or a non-strategic opponent. We find that when the strategy of the co-player is clear to the participants, the three types of implicatures are used to exploit the co-player's interpretation strategy. Indeed, participants use numeral implicatures as reliably as truth conditional content in all three conditions, while scalar quantifiers and ad hoc implicature elicit different strategies. We interpret these findings as evidence that speakers expect their interlocutors to infer implicatures from their utterances even in contexts where they know that they will be perceived as uncooperative.