Who Needs Emotions? The Brain Meets the Robot

how do we decipher others’ minds? 153
property of visual perception is a matter of speculation. The fact that young
infants are more interested by movements that look biological than by those
that look mechanical (e.g., Dasser, Ulbaek, & Premack, 1989) is an indication
in favor of the latter. Another argument is the fact that intentionality
of biological movements can be mimicked by the motion of objects, provided
this motion obeys certain rules. As shown by Heider and Simmel
(1944), seeing the self-propelled motion of geometrical stimuli can trigger
judgments of protosocial goals and intentions. The main condition is that
the object motion appears to be internally caused rather than caused by an
external force. A preference for self-propelled motion can be demonstrated
with this type of stimuli in 6-month-old infants (Gergely, Nadasdy, Czibra,
& Biro, 1995; Czibra et al., 1999).
Another critical aspect of communication between individuals is the faceperception
system. Faces, particularly in humans, carry an essential aspect
of the expression of emotions. Humans have a rich repertoire of facial gestures:
the eyes, the eyebrows, the forehead, the lips, the tongue, and the
jaws can move relative to the rest of the face. Not only can lip, tongue, and
jaw movements convey a speaker’s communicative intentions, but mouth
movements and lip positions can be powerful visual cues of a person’s emotional
states: by opening the mouth and moving the lips, a person can display
a neutral face, smile, laugh, or express grief. The movements and the
position of the eyes in their orbits also convey information about the person’s
emotional state, the likely target of attention and/or intention. To the same
extent as discussed for the perception of biological actions, the perception
of emotional expression on faces seems to stimulate a system tuned to extract
specific features of the visual stimulus. According to the influential
model of Bruce and Young (1986), a human face can give rise to two sorts
of perceptual process: perception of the invariant aspects and of the changing
aspects of a face. The former contributes to the recognition of the identity
of a person. The latter contributes to the perception of another’s social
intentions and emotional states.
The visual processing of face patterns has been a topic of considerable
interest for the past three decades. The neuropsychological investigation of
the condition known as “prosopagnosia” has revealed that patients with damage
to the inferior occipitotemporal region are selectively impaired in visual
face recognition, while their perception and recognition of other objects are
relatively unimpaired. As emphasized by Haxby, Hoffman, and Gobbini
(2000), face processing is mediated by a distributed neural system that includes
three bilateral regions in the occipitotemporal extrastriate cortex: the
inferior occipital gyrus, the lateral fusiform gyrus, and the superior temporal
sulcus. There is growing evidence that the lateral fusiform gyrus might
be specially involved in identifying and recognizing faces, that is, in the