In the present work we show the positive effects produced by reputation in reducing the uncertainty when users are faced with decisions. The effects are elicited and characterized by means of multi-agent based simulations of a computational model (Repage) which implements a cognitive theory of reputation.

The paper is structured as follows: in the first section, a cognitive theory of reputation is introduced; in the second section, the cognitive computational model (Repage) of such theory and the simulation scenarios are discussed. Finally results of a series of simulations aimed at outlining the capabilities of reputation in decision making are provided.

## 2 Reputation Theory

In this section we introduce briefly a cognitive theory of reputation [4] that is then simulated. More precisely, the reputation theory proposed in [4] introduces a fundamental distinction between *image* and *reputation* in social evaluations. Both are mental constructs, concerning other agents' (target) attitudes toward a given socially desirable behavior, that may be shared by a multitude of agents.

Image is an evaluative belief and asserts that the target is "good" when it displays certain behavior and "bad" in the opposite case. Reputation differs from image because it is true when the evaluation conveyed is actually widespread but not necessarily accurate. Furthermore, reputation circulates within society through gossip ([3]), that is a communication stream which allows, among other effects, cheaters to be found out or neutralised. To take place, reputation spreading needs four types of agents: evaluators, targets, gossipers and beneficiaries. As an example, the sentence "Silvio is considered an honest person", includes a set of evaluators (who adopt the evaluation), a single targets (Silvio), a set of beneficiaries (the people for which it is important to know that Silvio is an honest person) and the set of gossipers (who refer the evaluation as such, independent from its adoption).

Hence, to acknowledge the existence of a reputation does not imply to accept the evaluation itself. For instance, an agent A might have a very good image of agent B as a seller and at the same time recognize that there is a voice about agent B as a bad seller.

Unlike ordinary communication and deception, reputation does not bind the speaker to commit herself to the truth-value of the evaluation conveyed but only to the existence of rumors about it. Hence, reputation implies neither personal commitment nor responsibility over the evaluation transmission and on its consequences. It represents the agents' opinions about a certain target's attitude with respect to a specific norm or standard or her possession of a given skill. The reputation as described below has been adopted an studied in different contexts such as e-governance[11], and internet of services [9], the reputation systems [12],
and so forth.