Who Needs Emotions? The Brain Meets the Robot

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that are beneficial. The emotive system improves the performance of the
robot over that provided by the cognitive system alone.
Communicative Expression
Each emotive response entry of Table 10.2 is composed of a goal-achieving
behavioral component and an accompanying expressive display. For some
of the emotive responses, the expressive display addresses both aspects when
it serves a communicative function that is designed to elicit a desired behavioral
response from the human that satisfies the robot’s goal.
Kismet’s expressive abilities successfully serve its goals when interacting
with a person for two main reasons. First, we have found that people 1
enjoy playing with Kismet and want to sustain a pleasurable interaction with
it (Breazeal & Scassellati, 2000; Breazeal, 2002a, 2003a). People find the
robot to be lively and to have an appealing personality and convincing social
presence. This is a result of the way Kismet’s emotive system is designed to
interact with its cognitive system (as argued above, see Why Social/Sociable
Robots?). Thus, both Kismet and the person have the shared goal of establishing
and maintaining a beneficial interaction. The interaction is beneficial
to the human if it is enjoyable, and it is beneficial to the robot if its motivations
and goals are satisfied. Second, Kismet’s expressive behavior is effective
because it is readily understandable and predictable to the person who
interacts with it. This follows from the fact that Kismet’s emotive responses
are modeled after basic emotions that are universally understood by people
(Ekman, 1992). As a result, people readily infer how they must adapt their
behavior to obtain a desired response from Kismet—to keep it happy and
interested and to avoid causing it distress.
For instance, Kismet exhibits sorrow upon the prolonged absence of a
desired stimulus. This may occur if the robot has not been engaged with a
toy for a long time. The sorrowful expression is intended to elicit attentive
acts from the human analogous to how an infant’s cries elicit nurturing responses
from its caregiver. Kismet uses other expressive displays, such as
fearful expression to encourage people to slow down or back off a bit if they
are crowding its cameras or moving too fast for it to perceive them. This
allows the robot to tune the human’s behavior so that it is appropriate for
it. When the interaction is beneficial to Kismet, the robot conveys a state of
interest and joy that encourages people to sustain the interaction. In a number
of HRI studies with Kismet, we have found this to be quite effective as
people find pleasure in cheering up the robot and keeping it engaged without
being instructed to do so (Breazeal, 2003a).