A Fuzzy Implementation for the Socio-Cognitive Approach to Trust - Trust Theory: A Socio-Cognitive and Computational Model - page 301

11.3 Belief Sources
As shown in Chapter 2, our trust model is essentially based on specific beliefs which are both
a basis of trust and also its sub-components or parts . These beliefs are the analytical account
and the components of trust, and we derive thedegreeoftrust directly from the strength of its
componential and supporting beliefs (see Chapter 3): the quantitative dimensions of trust are
based on the quantitative dimensions of its cognitive constituents .
However, what is the origin and the justification of the strength of beliefs? Our answer is: Just
their sources. In our model, depending on the nature, the number, the convergence/divergence,
and the credibility of its sources a given belief is more or less strong (certain, credible).
Several models propose a quantification of the degree of trust and make it dynamic, i.e. they
can change and update such a degree (Jonker & Treur, 1999), (Schilloet et al. , 1999). But they
only consider direct interaction (experience) or reputation as sources. In this implementation
we have considered four possible types of belief sources:
direct experience (how the personal - positive or negative - experience of the trustor
contributes to that belief);
categorization (how the properties of a class are transferred to their members);
reasoning (more general than just categorization); and
reputation (how the other's experience and opinion influences the trustor beliefs).
We do not consider learning in the model's dynamic. We are just modeling the resulting
effects that a set of trustor's basic beliefs (based on various sources) have on the final evaluation
of the trustee's trusfulness about a given task and in a specific situation. At present we do not
consider how these effects feed back on the basic beliefs.
11.4 Building Belief Sources
Agents act depending on what they believe, i.e. relying on their beliefs. And they act on the
basis of the degree of reliability and certainty they attribute to their beliefs. In other words,
trust/confidence in an action or plan (reasons to choose it and expectations of success) is
grounded on and derives from trust/confidence in the related beliefs.
For each kind of source we have to consider the impact it produces on trustor's beliefs
about trustee's features. These impacts result from the composition of the value of the content
(property) of that specific belief (the belief's object) with a subjective modulation introduced
by some epistemic evaluations about that specific source. In fact when we have a belief we
have to evaluate:
the value of the content of that belief;
what the source is (another agent, my own inference process, a perceptive sense of mine,
etc.);
how this source evaluates the belief (the subjective certainty of the source itself);
how the trustor evaluates this source (with respect to this belief).