Who Needs Emotions? The Brain Meets the Robot

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see Zajonc, 1985), the imaginary results proposed here seem highly plausible.
We will come back later to other experiments that strongly support
the present speculation. Experiencing and watching (an action, an emotion)
would thus be two faces of the same coin. The problem with such examples,
however, is that they remain within the realm of nonintentional communication
and explore only some basic conditions for understanding the observed
agent. This limitation, which also extends to the brain-mapping experiments
to be described below, has to be kept in mind for evaluating the relevance
of the simulation theory as an explanation for understanding other people’s
minds.
A critical condition for assigning motor images and observed actions the
status of covert and simulated actions is that they should activate brain areas
known to be devoted to executing actions. Early work by Ingvar and
Philipsson (1977), using measurement of local cerebral blood flow, had
showed that “pure motor ideation” (e.g., thinking of rhythmic clenching
movements) produced a marked frontal activation and a more limited activation
in the area of the motor cortex. More recent brain mapping experiments,
using positron emission tomography (PET) or functional magnetic
resonance imaging (fMRI), have led to the conclusion that represented actions
involve a subliminal activation of the motor system (Jeannerod, 1999,
2001; Jeannerod & Frak, 1999). They show the existence of a cortical and
subcortical network activated during both motor imagery and action observation.
This network involves structures directly concerned with motor
execution, such as the motor cortex, dorsal and ventral premotor cortex,
lateral cerebellum, and basal ganglia; it also involves areas concerned with
action planning, such as the dorsolateral prefrontal cortex and posterior
parietal cortex. Concerning the primary motor cortex itself, fMRI studies
unambiguously demonstrate that voxels activated during contraction of a
muscle are also activated during imagery of a movement involving the same
muscle (Roth et al., 1996). During action observation, the involvement of
primary motor pathways was demonstrated using direct measurement of
corticospinal excitability by transcranial magnetic stimulation. Fadiga, Fogassi,
Pavesi, and Rizzolatti (1995) found that subjects observing an actor executing
hand-grasping movements were more responsive to stimulation in their
own hand motor area. The area involved during observation of the hand
movements was superimposed with that activated while the subjects themselves
actually performed the movement.
In principle, a theory that postulates that both actions of the self and
actions of the other can be distinguished on the basis of their central representations
should predict separate representations for these two types of
action. At the neural level, one should expect the existence of different
networks devoted to action recognition, whether the action originates from