Towards modeling trust based decisions: A game theoretic approach

Current trust models enable decision support at an implicit level by means of thresholds or constraint satisfiability. Decision support is mostly included only for a single binary action, and does not explicitly consider the purpose of a transaction. In this paper, we present a game theoretic model that is specifically tuned for decision support on a whole host of actions, based on specified thresholds of risk. As opposed to traditional representations on the real number line between 0 and +1, Trust in our model is represented as an index into a set of actions ordered according to the agent's preference. A base scenario of zero trust is defined by the equilibrium point of a game described in normal form with a certain payoff structure. We then present the blind trust model, where an entity attempts to initiate a trust relationship with another entity for a one-time transaction, without any prior knowledge or recommendations. We extend this to the incentive trust model where entities can offer incentives to be trusted in a multi-period transaction. For a specified risk threshold, both models are analyzed by using the base scenario of zero trust as a reference. Lastly, we present some issues involved in the translation of our models to practical scenarios, and suggest a rich set of extensions of the generalized game theoretic approach to model decision support for existing trust frameworks.