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162 Socially Intelligent Agents

4.2 Action capture

Action capture is defined as the act of mapping another person’s bodily
movements or postures onto one’s own motor program or proprioception. This
mapping connects different modalities; one observes another person’s body ex-
teroceptively (mainly visually) and moves or proprioceptively feels one’s own
body, as shown in Figure 19.5. Together with joint attention, action capture
enables the robot to indirectly experience someone else’s behavior, by trans-

lating the other person’s behavior i, o into its own virtual behavior i ,o ,as
illustrated in Figure 19.6.

seeing
someone
else’s moving
body one’s
(extero- own
ception) body
(proprio-
ception)
caregiver
robot

Figure 19.5. Mapping between self and another person.

i
• •
o
another object
o i
• •
self

Figure 19.6. Indirect experience of another person’s behavior.

A number of researchers have suggested that people are innately equipped
with the ability to capture another person’s actions; some of the mechanisms
they have cited are neonatal mimicry [6] and mirror neurons [7]. Neonatal
mimicry of some facial expressions is, however, so restricted that it does not
fully account for our capability of whole-body imitation. Mirror neurons found
in the pre-motor cortex of macaques activate when they observe someone doing
a particular action and when they do the same action themselves. However, the
claim that mirror neurons are the innate basis for action capture is not clear,
since macaques do not imitate at all [4, 9].