Page 92 - Designing Sociable Robots

breazeal-79017 book March 18, 2002 14:2

The Vision System 73

Attention Gains
30
Deviation from default –10 0
20
10

Face gain
Motion gain
–20
Color gain
–30
0 50 100 150 200
Time (seconds)
Interactions with a Person
2000
1000
Activation 0 Social drive
Seek people
–1000 Engage people
Avoid people
Face percept
–2000
0 50 100 150 200
Time (seconds)
Interactions with a Toy
2000
1000
Activation 0 Stimulation drive
Seek toy
–1000 Engage toy
Avoid toy
Color percept
–2000
0 50 100 150 200
Time (seconds)
Figure 6.7
Changes of the skin tone, motion, and color gains from top-down motivational and behavioral influences (top).
On the left half of the top figure, the gains change with respect to person-related behaviors (middle figure). On the
right half of the top figure, the gains change with respect to toy-related behaviors (bottom figure).

The relative weighting of the attention gains are empirically set to satisfy behavioral
performance as well as to satisfy social interaction dynamics. For instance, when engaging
in visual search, the attention gains are set so that there is a strong preference for the target
stimulus (skin tone when searching for social stimuli like people, saturated color when
searching for non-social stimuli like toys). As shown in figure 6.3, a distant face has greater
overall saliency than a nearby toy if the robot is actively looking for skin-toned stimuli.
Similarly, as shown to the right in figure 6.3, a distant toy has greater overall saliency than
a nearby face when the robot is actively seeking out stimuli of highly saturated color.