Page 169 - Designing Sociable Robots

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150 Chapter 9

the robot. In addition, Kismet vocalizes excitedly, which is perceived as an initiation. The
FSM transitions to the second state (2) upon the completion of this gesture. In this state, the
robot “sits back” and waits for a bit with an expectant expression (ears slightly perked, eyes
slightly widened, and brows raised). If the person has not already approached the robot, it is
likely to occur during this “anticipation” phase. If the person does not approach within the
allotted time period, the FSM transitions to the third state (3) where face relaxes, the robot
maintains a neutral posture, and gaze fixation is released. At this point, the robot is able to
shift gaze. As long as this FSM is active (determined by the behavior system), the calling
cycle repeats. It can be interrupted at any state transition by the activation of another FSM
(such as the greeting FSM when the person has approached). Chapter 10 presents a table
and summary of FAPs that have been implemented on Kismet.

9.6 Playful Interactions with Kismet

The behavior system implements the four classes of proto-social responses. The robot dis-
plays affective responses by changing emotive facial expressions in response to stimulus
quality and internal state. These expressions relate to goal achievement, emotive reactions,
and reflections of the robot’s state of “well-being.” The exploratory responses include vi-
sual search for desired stimuli, orientation, and maintenance of mutual regard. Kismet has
a variety of protective responses that serve to distance the robot from offending stimuli.
Finally, the robot has a variety of regulatory responses that bias the caregiver to provide
the appropriate level and kinds of interactions at the appropriate times. These are commu-
nicated to the caregiver through carefully timed social displays as well as affective facial
expressions. The organization of the behavior system addresses the issues of relevancy,
coherency, persistence, flexibility, and opportunism. The proto-social responses address the
issues of believability, promoting empathy, expressiveness, and conveying intentionality.
Regulating Interaction

Figure 9.9 shows Kismet responding to a toy with these four response types. The robot
begins the trial looking for a toy and displaying sadness (an affective response). The robot
immediately begins to move its eyes searching for a colorful toy stimulus (an exploratory
response) (t < 10). When the caregiver presents a toy (t ≈ 13), the robot engages in a play
behavior and the stimulation-drive becomes satiated (t ≈ 20). As the caregiver moves
the toy back and forth (20 < t < 35), the robot moves its eyes and neck to maintain the
toy within its field of view. When the stimulation becomes excessive (t ≈ 35), the robot
becomes first “displeased” and then “fearful” as the stimulation-drive moves into
the overwhelmed regime. After extreme over-stimulation, a protective escape response
produces a large neck movement (t = 38), which removes the toy from the field of view.