Page 119 - Designing Sociable Robots

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100 Chapter 7

Discussion

Results from these initial studies and other informal observations suggest that people do
naturally exaggerate their prosody (characteristic of motherese) when addressing Kismet.
People of different genders and ages often comment that they find the robot to be “cute,”
which encourages this manner of address. Naive subjects appear to enjoy interacting with
Kismet and are often impressed at how life-like it behaves. This also promotes natural
interactions with the robot, making it easier for them to engage the robot as if it were a very
young child or adored pet.
All female subjects spoke to Kismet using exaggerated prosody characteristic of infant-
directed speech. It is quite different from the manner in which they spoke with the experi-
menters. I have informally noticed the same tendency with children (approximately twelve
years of age) and adult males. It is not surprising that individual speaking styles vary. Both
children and women (especially women with young children or pets) tend to be uninhib-
ited, whereas adult males are often more reserved. For those who are relatively uninhibited,
their styles for conveying affective communicative intent vary. However, Fernald’s contours
hold for the strongest affective statements in all of the languages that were explored in this
study. This would account for the reasonable classifier performance on vocalizations be-
longing to the strongest affective category of each class. As argued previously, this is the
desired behavior for using affective speech as an emotion-based saliency marker for training
the robot.
For each trial, we recorded the number of utterances spoken, Kismet’s cues, the subject’s
responses and comments, as well as changes in prosody, if any. Recorded events show
that subjects in the study made ready use of Kismet’s expressive feedback to assess when
the robot “understood” them. The robot’s expressive repertoire is quite rich, including
both facial expressions and shifts in body posture. The subjects varied in their sensitivity
to the robot’s expressive feedback, but all used facial expression and/or body posture to
determine when the utterance had been properly communicated to the robot. All subjects
would reiterate their vocalizations with variations about a theme until they observed the
appropriate change in facial expression. If the wrong facial expression appeared, they often
used strongly exaggerated prosody to correct the “misunderstanding.”
Kismet’sexpressionthroughfaceandbodyposturebecomesmoreintenseastheactivation
level of the corresponding emotion process increases. For instance, small smiles versus
large grins were often used to discern how “happy” the robot was. Small ear perks versus
widened eyes with elevated ears and craning the neck forward were often used to discern
growing levels of “interest” and “attention.” The subjects could discern these intensity
differences, and several modulated their speech to influence them. For example, in one trial
a subject scolded Kismet, to which it dipped its head. However, the subject continued to