Page 144 - Designing Sociable Robots

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The Motivation System 125

not tried to experiment with different synthetic personalities. This could be an interesting
set of studies.
This leads us to a discussion of both an important feature and limitation of the motivation
system—the number of parameters. Motivation systems of this nature are capable of pro-
ducing rich, dynamic, compelling behavior at the expense of having many parameters that
must be tuned. For this reason, systems of the complexity that rival Kismet are hand-crafted.
If learning is introduced, it is done so in limited ways. This is a trade-off of the technique,
and there are no obvious solutions. Designers scale the complexity of these systems by
maintaining a principled way of introducing new releasers, appraisals, elicitors, etc. The
functional boundaries and interfaces between these stages must be honored.

8.6 Summary

Kismet’s emotive responses enable the robot to use social cues to tune the caregiver’s
behavior so that both perform well during the interaction. Kismet’s motivation system is
explicitlydesignedsothatastateof“well-being”fortherobotcorrespondstoanenvironment
that affords a high learning potential. This often maps to having a caregiver actively engaging
the robot in a manner that is neither under-stimulating nor overwhelming. Furthermore, the
robot actively regulates the relation between itself and its environment, to bring itself into
contact with desired stimuli and to avoid undesired stimuli. All the while, the cognitive
appraisals leading to these actions are displayed on the robot’s face. Taken as a whole,
the observable behavior that results from these mechanisms conveys intentionality to the
observer. This is not surprising as they are well-matched to the proto-social responses of
human infants. In numerous examples presented throughout this book, people interpret
Kismet’s behavior as the product of intents, beliefs, desires, and feelings. They respond to
Kismet’s behaviors in these terms. This produces natural and intuitive social exchange on
a physical and affective level.