Who Needs Emotions? The Brain Meets the Robot

eware the passionate robot 369
Where Fellous and LeDoux emphasize working memory in their cortical
model and include the orbital cortex as part of this cortical refinement,
Rolls (1999) includes the orbitofrontal cortex in both routes of his two-route
model. Before we look at this model, though, one caveat about Rolls’ general
view that emotions are states elicited by rewards and punishers. Rolls
states that his approach helps with understanding the functions of emotion,
classifying different emotions, and understanding what information processing
systems in the brain are involved in emotion and how they are involved.
Indeed it does but, where Rolls emphasizes the polarity between reward and
punishment, I would rather ground a theory of emotions in the basic drives
of Arbib and Lieblich (1977) as seen in the basic hypothalamic and midbrain
nuclei of Swanson’s (2000) behavioral control column and the basic
neuromodulatory systems of Fellous (1999) and Kelley (Chapter 3). Where
Rolls argues that brains are designed around reward-and-punishment evaluation
systems because this is the way that genes can build a complex system
that will produce appropriate but flexible behavior to increase their fitness,
I would stress (with Swanson) the diversity of specific motor and perceptual
systems that the genes provide, while agreeing that various learning
systems, based on various patterns of error feedback as well as positive and
negative reinforcement, can provide the organism with adaptability in building
upon this basic repertoire that would otherwise be unattainable. (Consider
Figure 12.2 to see how much machinery evolution has crafted beyond
basic drives and incentives, let alone simple reward and punishment.)
Rolls argues that there are two types of route to action performed in relation
to reward or punishment in humans. The first route (see the middle
row of Fig. 5.2) includes the amygdala and, particularly well-developed in
primates, the orbitofrontal cortex. These systems control behavior in relation
to previous associations of stimuli with reinforcement. He notes various properties
of this system, such as hysteresis, which prevents an animal that is equally
hungry and thirsty from continually switching back and forth between eating
and drinking. In other words, despite the emphasis that Rolls lays on reward
and punishment, the analysis is in many ways linked to the differential effects
of different drive systems. The second route (see the top row of Fig. 5.2) involves
a computation with many “if . . . then” statements, to implement a plan
to obtain a reward. Rolls argues that syntax is required here because the many
symbols that are part of the plan must be correctly linked, as in: “if A does
this, then B is likely to do this, and this will cause C to do this.” I think Rolls
may be mistaken to the extent that he conflates syntax in simple planning with
the explicit symbolic expression of syntax involved in language. Nonetheless
(as in the Arbib-Hesse theory), I do agree that the full range of emotion in
humans involves the interaction of the language system with a range of other
systems. Rolls holds that the second route is related to consciousness, which