Who Needs Emotions? The Brain Meets the Robot

162 brains
situations where they have to attribute a movement to its author. For example,
the situation can be such that the movements patients execute with their own
hands differ from the movements they see when shown the movements of a
hand of an uncertain origin (a hand that could equally likely belong to them
or to someone else). In this situation, schizophrenic patients tend to massively
attribute these movements to themselves (Daprati et al., 1997). These attribution
errors might be the consequence of an impairment in detecting some
aspects of biological movements, like their direction (Franck et al., 2001).
Perceiving the direction of a movement is indeed useful information for an
observer to understand the action of the agent of this movement: during a
movement, the arm points to the goal of the action, and its direction may reveal
the intention of the agent. It is thus not surprising that a patient deprived of
this information will misinterpret the intention displayed by others in their
movements and that this will have consequences for attributing actions to their
agent and ultimately understanding interactions between people.
Misrecognition of one’s own movements is also a highly plausible
explanation for another typical symptom that is of the first rank in Schneider’s
sense, verbal hallucinations. As mentioned above, auditory verbal hallucinations
in schizophrenic patients are related to the production of their own
speech: they perceive their inner speech as voices arising from an external
source. Experiments using neuroimaging techniques have greatly contributed
to the study of this problem by examining brain activation during hallucinations
or during inner speech in patients predisposed to hallucinations
and subjects experiencing no hallucinations. The results show that, during
hallucinations (as signaled by the patients), brain metabolism is increased in
the primary auditory cortex (Heschl’s gyrus) on the left side (Dierks et al.,
1999), as well as in the basal ganglia (Silbersweig et al., 1995). Thus, whereas
self-generated inner speech is normally accompanied by a mechanism that
decreases the responsiveness of the primary auditory cortex, during verbal
hallucinations, the auditory temporal areas remain active, which suggests that
the nervous system in these patients behaves as if it were actually processing
the speech of an external speaker.
The obvious question at this point is whether patients of this sort would
also fail to detect (and therefore to attribute) emotions expressed by other
individuals. This seems to be confirmed by the abundant literature on the
processing of emotion in schizophrenia. Schizophrenic patients typically fail
to detect facial expressions of emotions (e.g., Feinberg, Rifkin, Schaffer, &
Walker, 1986; see review in Baudouin et al., 2002). In addition, these patients
also have decreased responsiveness to emotional stimuli: their observable
facial expressiveness in response to emotional stimuli is decreased (e.g.,
Berenbaum & Oltmanns, 1992).