Persuasion Strategies in Dialogue

In this abstract we consider dialogues that have a normative aspect. A dialogue is regulated by norms, but can also establish new norms. Certain utterances ‘count as’ a particular dialogue move in some dialogue game, which creates obligations and permissions for the participants. But norms do not operate in isolation; we study their relation to mental attitudes of participants, in particular beliefs (information), desires, goals or intentions. In particular, we study dialogues in which one agent is trying to influence the behaviour of another agent. For lack of a better name, we call these persuasion dialogues, although we realise they do not conform to the strict definition which requires a conflict between beliefs to be resolved by an exchange of arguments [8, p66]. In general, one might say that there are three ways of influencing behaviour, each corresponding to the manipulation of one of the mental attitudes. One can influence behaviour by issuing a command, which essentially adds an obligation; by convincing, which means that desires or intentions are changed, and finally by suggestion, through altering the beliefs on the basis of which an agent makes decisions. These strategies have different requirements regarding the social setting of the dialogue. For example, for commands an authority relationship between agents is necessary. To understand the strategies, we need a model of the decision making of agents, which incorporates both norms and individual mental attitudes like beliefs and goals. In previous work [1, 3, 2] we have presented a detailed model of normative multi-agent systems, which covers both individual agents and norms. We believe that an authority can be modelled as an agent like other agents. In some authoritarian settings, the goals of the normative agent become obligations for the subjects. In other settings, more elaborate violation detection and sanctioning mechanisms are needed. Recursive modelling is used to predict behaviour of agents, and to test if norms will be obeyed or not. Dynamic changes to a normative system can be accounted for by adding or deleting obligations [7]. What has not yet been done, is to link such changes to dialogue moves. In dialogue, an utterance ‘counts as’ or constitutes a move in a dialogue game [6]. The borderline of what utterances count as what moves is open to interpretation. However, once there is agreement on a particular move, participants must respond accordingly [5]. Therefore, in this abstract we want to extend the framework of normative multi-agent systems with dialogue moves, response obligations and ‘count as’ constitutive norms, such that we can conceptualise and explain the three kinds of persuasion strategies. To this end we propose a dialogue model in which a record is kept of the individual obligations and permissions of participants, along with records of their apparent information and goals, on the basis of what was said.