Page 27 - Designing Sociable Robots

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8 Chapter 1

beings and are able to do so quite early in our development (Trevarthen, 1979). We tend
to interpret behavior (such as self-propelled movement) as being intentional, whether it is
demonstrated by a living creature or not (Premack & Premack, 1995). When engaging a
non-living agent in a social manner, people show the same tendencies (Reeves & Nass,
1996). Ideally, humans would interact with robots as naturally as they interact with other
people. To facilitate this kind of social interaction, robot behavior should reflect life-like
qualities. Much attention has been directed to giving Kismet’s behavior this quality so that
people will engage the robot naturally as a social being.
Living agents such as animals and humans are autonomous. They are capable of promot-
ing their survival and performing tasks while negotiating the complexities of daily life. This
involves maintaining their desired relationship with the environment, yet they continually
change this balance as resources are competed for and consumed. Robots that share a social
environment with others must also able to foster their continued existence while performing
their tasks as they interact with others in an ever-changing environment.
Autonomy alone is not sufficiently life-like for human-style sociability, however. Inter-
acting with a sociable robot should not be like interacting with an ant or a fish, for instance.
Although ants and fish are social species, they do not support the human desire to treat others
as distinct personalities and to be treated the same in turn. For this reason, it is important
that sociable robots be believable.
The concept of believability originated in the arts for classically animated characters
(Thomas & Johnston, 1981) and was later introduced to interactive software agents (Bates,
1994). Believable agents project the “illusion of life” and convey personality to the human
who interacts with it. To be believable, an observer must be able and willing to apply
sophisticated social-cognitive abilities to predict, understand, and explain the character’s
observable behavior and inferred mental states in familiar social terms. Displaying behaviors
such as giving attention, emotional expression, and playful antics enable the human observer
to understand and relate to these characters in human terms. Pixar and Walt Disney are
masters at creating believable characters, animating and anthropomorphizing nature and
inanimate objects from trees to Luxo lamps. An excellent discussion of believability in
robots can be found in Dautenhahn (1997, 1998).
Human-Aware

To interact with people in a human-like manner, sociable robots must perceive and under-
stand the richness and complexity of natural human social behavior. Humans communicate
with one another through gaze direction, facial expression, body movement, speech, and
language, to name a few. The recipient of these observable signals combines them with
knowledge of the sender’s personality, culture, past history, the present situational context,
etc., to infer a set of complex mental states. Theory of mind refers to those social skills