Computational Trust - Defining Trust

Defining Trust

These concepts have been acquiring a great relevance in the last decade in the computer science field, mostly in the area of distributed artificial intelligence. The multi-agent system paradigm and the huge evolution of e-commerce are factors that contributed to the increase of interest on trust and reputation. In fact, Trust and reputation systems have been recognized as the key factors for a successful electronic commerce adoption. These systems are used by intelligent software agents as an incentive in decision-making, when deciding whether or not to honor contracts, and as a mechanism to search trustworthy exchange partners. In particular, reputation is used in electronic markets as a trust-enforcing mechanism or as a method to avoid cheaters and frauds.

Another area of application of these concepts, in agent technology, is teamwork and cooperation. Several definitions of the human notion of trust have been proposed during the last years in different domains from sociology, psychology to political and business science. These definitions may even change in accordance with the application domain. For example, Romano’s recent definition tries to encompass the previous work in all these domains:

Trust is a subjective assessment of another’s influence in terms of the extent of one’s perception about the quality and significance of another’s impact over one’s outcomes in a given situation, such that one’s expectation of, openness to, and inclination toward such influence provide a sense of control over the potential outcomes of the situation.

Trust and reputation both have a social value. When someone is trustworthy, that person may be expected to perform in a beneficial or at least not in a suspicious way that assure others, with high probability, good collaborations with him. On the contrary, when someone appears not to be trustworthy, others refrain from collaborating since there is a lower level of probability that these collaborations will be successful.

Trust is a particular level of the subjective probability with which an agent assesses that another agent or group of agents will perform a particular action, both before he can monitor such action (or independently or his capacity ever to be able to monitor it) and in a context in which it affects his own action.

Trust is strongly connected to confidence and it implies some degrees of uncertainty, hopefulness or optimism. Eventually, Marsh addressed the issue of formalizing trust as a computational concept in his PhD thesis. His trust model is based on social and psychological factors.