Who Needs Emotions? The Brain Meets the Robot

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cortex and basal ganglia in the brain, which receive input from
structures such as the orbitofrontal cortex and amygdala that
compute the rewards (see Fig. 5.2; Rolls, 1999a).
3. Motivation. Emotion is motivating, as just described. For example,
fear learned by stimulus–reinforcement association provides
the motivation for actions performed to avoid noxious stimuli.
Genes that specify goals for action, such as rewards, must as an
intrinsic property make the animal motivated to obtain the reward;
otherwise, it would not be a reward. Thus, no separate
explanation of motivation is required.
4. Communication. Monkeys, for example, may communicate their
emotional state to others by making an open-mouth threat to
indicate the extent to which they are willing to compete for
resources, and this may influence the behavior of other animals.
This aspect of emotion was emphasized by Darwin (1872/1998)
and has been studied more recently by Ekman (1982, 1993).
Ekman reviews evidence that humans can categorize facial
expressions as happy, sad, fearful, angry, surprised, and disgusted
and that this categorization may operate similarly in different
cultures. He also describes how the facial muscles produce different
expressions. Further investigations of the degree of crosscultural
universality of facial expression, its development in
infancy, and its role in social behavior are described by Izard
(1991) and Fridlund (1994). As shown below, there are neural
systems in the amygdala and overlying temporal cortical visual
areas which are specialized for the face-related aspects of this
processing. Many different types of gene-specified reward have
been suggested (see Table 10.1 in Rolls, 1999a) and include not
only genes for kin altruism but also genes to facilitate social
interactions that may be to the advantage of those competent
to cooperate, as in reciprocal altruism.
5. Social bonding. Examples of this are the emotions associated with
the attachment of parents to their young and the attachment of
young to their parents. The attachment of parents to each other
is also beneficial in species, such as many birds and humans,
where the offspring are more likely to survive if both parents
are involved in the care (see Chapter 8 in Rolls, 1999a).
6. The current mood state can affect the cognitive evaluation of
events or memories (see Oatley & Jenkins, 1996). This may facilitate
continuity in the interpretation of the reinforcing value of
events in the environment. The hypothesis that backprojections
from parts of the brain involved in emotion, such as the orbito-