Page 250 - Designing Sociable Robots

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Grand Challenges of Building Sociable Robots 231

Female subjects are willing to use exaggerated prosody when talking to Kismet, character-
istic of motherese. Both male and female subjects tend to sit directly in front of and close to
Kismet, facing it the majority of the time. When engaging Kismet in proto-dialogue, they
tend to slow down, use shorter phrases, and wait longer for Kismet’s response. Some sub-
jects use exaggerated facial expressions. All these behaviors are characteristic of interacting
with very young animals (e.g., puppies) or infants.

Self-motivated interaction Kismet exhibits self-motivated and proactive behavior.
Kismet is in a never-ending cycle of satiating its drives. As a result, the stimuli it ac-
tively seeks out (people-like things versus toy-like things) changes over time. The first level
of the behavior system acts to seek out the desired stimulus when it is not present, to engage
it when it has been found, and to avoid it if it is behaving in an offensive or threatening
manner. The gains of the attention system are dynamically adjusted over time to facilitate
this process. Kismet can take the initiative in establishing an interaction. For instance, if
Kismet is in the process of satiating its social-drive, it will call to a person who is present
but slightly beyond face-to-face interaction distance.
Regulation of interactions Kismet is well-versed in regulating its interactions with the
caregiver. It has several mechanisms for accomplishing this, each for different kinds of
interactions. They all serve to slow the human down to an interaction rate that is within
the comfortable limits of Kismet’s perceptual, mechanical, and behavioral limitations. By
doing so, the robot is neither overwhelmed nor under-stimulated by the interaction.
The robot has two regulatory systems that serve to maintain the robot in a state of “well-
being.” These are the emotive responses and the homeostatic regulatory mechanisms. The
drives establish the desired stimulus and motivate the robot to seek it out and to engage it.
The emotions are another set of mechanisms, with greater direct control over behavior and
expression, that serve to bring the robot closer to desirable situations (joy, interest,even
sorrow), and cause the robot to withdraw from or remove undesirable situations (fear,
anger,or disgust). Which emotional response becomes active depends largely on the
releasers, but also on the internal state of the robot. The behavioral strategy may involve
a social cue to the caregiver (through facial expression and body posture) or a motor skill
(such as the escape response). The use of social amplification to define a personal space is
a good example of how social cues, that are a product of emotive responses, can be used to
regulate the proximity of the human to the robot. It is also used to regulate the movement
of toys when playing with the robot.
Kismet’s turn-taking cues for regulating the rate of proto-dialogue is another case. Here,
the interaction happens on a more tightly coupled temporal dynamic between human and
robot. The mechanism originates from the behavior system instead of the emotion system.
It employs communicative facial displays instead of emotive facial expressions. Our studies