Computational Intelligence - May 2013 - 75

CtxPrf ({U bt, U al, U 17}, ag) - 0.820
As we have shown (see Section Vii-B), wishful thinking
CtxPrf ({U bt, U al, JU 17, U cr }, ag) - 0.856
CtxPrf ({U bt, U 17, U cr }, ag) - 0.833
in WTR is not merely a bias in the resolution of
CtxPrf ({JU bt, U al, U 17}, ag) - 1.804
conflicts among inconsistent data (passive effects); it
CtxPrf ({JU bt, U al, JU 17, U cr }, ag) - 1.846
can sometimes be the sole cause for having a belief,
CtxPrf ({JU bt, U 17, U cr }, ag) - 1.819.
Consequently, the believed context is
or for evoking belief revision when certain beliefs are
c
b = {JU bt, U al, JU 17, U cr }, and the resulting
undesirable (active effects).
belief space is BS ( b c, ag) = {JU bt, U al,
JU 17, U cr ,} .
Both DBR and WTR are approaches to belief dynamics,
Susan's communication was "just what the agent wanted to
for autonomous agents. They both produce non-prioritized
hear" to be able to deny, once again, her mother's death. The
belief revision that is biased by the likeability of beliefs. Also,
new hypothesis is that the agent's mother did not board flight
both models measure this likeability according to the satisfac17 (JU 17), so U 17 becomes, once again, easy to reject.
tion of goals; Affective states are not modeled explicitly, but
This result illustrates an important aspect of WTR. Notice
rather implicitly, through the preference conveyed by likeability.
that the fact that the agent's mother boarded flight 17 is supOne of the main differences between the two models is
ported by communications from David and Bruno, and:
that DBR is belief-oriented while WTR is context oriented,
❏ Without wishful thinking, the agent would never reject this
and this difference is specially important in the determination
belief because it is the word of both David and Bruno against
of likeability.
the word of Susan, and even Bruno, alone, is considered
As explained in Section I, a context-oriented approach is
more credible than Susan (the causal strength of U 17 is 0.9
more adequate, since the preference of a belief may be depenwhile the causal strength of JU 17, is 0.6).
dent on certain other beliefs being kept or abandoned. This is
❏ Wishful thinking alone (in this situation) is also not enough
mostly obvious when it comes to the preference conveyed by
to allow the agent to reject such a strong belief ( U 17 ), as can
likeability because, for instance, a belief may be desired/undebe concluded from the results of Scenario 4.
sired only due to the presence of another belief.
Therefore, the denial that occurs in this scenario was only
Another important difference, between the two approaches,
possible because of a combination of rational and affective facis that, in WTR, we model active effects of wishful thinking, an
tors (i.e., the support from Susan's communication combined
aspect that is not modeled in DBR. More concretely, in DBR
with the agent's desire to believe that her mother is alive). This
beliefs originate from data which, in turn, comes from the outcombined effect captures, in WTR, the passive effects of wishside world. The only internally generated beliefs are those that
ful thinking, explained in Section III.
originate from other beliefs, through inference. In WTR, howWTR is guided by an order (or orders) among contexts
ever, beliefs can also originate from goals, by means of wishful
that does not necessarily have a correspondence to some order
thinking supports. Any inconsistencies, between these wishful
(or orders) among hypotheses. For instance, suppose that,
thoughts and collected data, trigger belief revision, the same
because JU 17 is in the believed context and U 17 is not (in
way inconsistencies among collected data do.
this scenario), we assume an order among hypotheses where
In [7], Jonathan Gratch and Stacy Marsella start by presentJU 17 is preferred to U 17 . Notice that this preference is a coning a framework that describes appraisal and coping as two
sequence of the agent's belief in U cr (that makes U 17
strongly related operations. As the authors put it, "Appraisal
"unwanted," given her goals). If, for some reason, the agent
characterizes the relationship between a person and their physirejects the belief in U cr the resulting order, between JU 17 and
cal and social environment (...) and coping recruits resources to
U 17 , is reversed.
repair or maintain this relationship" [7].
This view is based on Smith and Lazarus' cognitive motivaViii. Comparison with Related Work
tional-emotive system [21]. Gratch and Marsella describe this
In the previous sections we have presented the WTR framesystem's architecture, highlighting that the consequence of
work, and shown how it can be used to manage an agent's
appraisal (the action tendencies, the affect and the physiological
beliefs according to the aims discussed in Section I. In this secresponses) triggers coping which, in turn, acts on the antecedtion we compare WTR with two other approaches that are
ents of appraisal. These antecedents may be the environment, in
related to some extent.
the case of problem-focused coping, or the evaluation of the
In [17] and [18], Fabio Paglieri presents an approach to belief
situation, in the case of emotion-focused coping. Following the
revision in the context of cognitive agents: Dataoriented Belief
guidelines of this framework, the authors implement a specific
Revision (in short, DBR). More precisely, DBR is a model of cogcomputational model: EMA [7], [13] (named after Lazarus'
nitive agents' epistemic dynamics (of which belief revision is a
book "Emotion and Adaptation" [10]).
part). The model builds upon the distinction between data (inforNote that coping commonly refers to how the individual
mation stored in the agent's mind) and beliefs (information the
deals with strong negative emotions. Although the authors
agent considers reliable for further reasoning and direct action).
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May 2013 | IEEE CoMputatIonal IntEllIgEnCE MagazInE

Table of Contents for the Digital Edition of Computational Intelligence - May 2013