Who Needs Emotions? The Brain Meets the Robot

architectural basis of affect 237
muscles, skin, circulatory system, hormonal systems, etc.). If the presence of
an emotion requires a body of a particular type (e.g., with chemical hormones),
then there may never be (nonbiological) robots with emotions.
Alternatively, one could take emotion terms to refer to states and processes
in virtual machines that happen to be implemented in these particular
physical mechanisms but might in principle be implemented in different
mechanisms. In that case, nonbiological artifacts may be capable of implementing
emotions as long as they are capable of implementing all relevant
causal relationships that are part of the definition of the emotion term. The
above alternatives are not mutually exclusive, for there is nothing to rule
out the combination of
deep, implementation-neutral, architecture-based concepts of
emotion, definable in terms of virtual machine architectures
without reference to implementation-dependent properties of
the physical substratum
special cases (i.e., subconcepts) that are implementationdependent
and defined in terms of specific types of body and how
they express their states (e.g., snarling, weeping, grimacing, tensing,
changing color, jumping up and down, etc.).
LeDoux (1996) and Panksepp (1998) present such special cases, where
emotions are defined in terms of particular brain regions and pathways. These
definitions are intrinsically dependent on a particular bodily make-up (i.e.,
anatomical, physiological, chemical, etc.). Hence, systems that do not possess
the required type of body cannot, by definition, implement them.
The conceptual framework of Ortony, Clore, and Collins (1988; and see
Chapter 7), however, is an example of an implementation-neutral conception,
where emotions are defined in terms of an ontology that distinguishes
events, objects, and agents and their different relationships to the system that
has the emotion. It is interesting to note that if emotions are reactions to
events, agents, or objects (as Ortony and co-workers claim), then their
agent-based emotions (i.e., emotions elicited by agents) cannot occur in
architectures that do not support representations of the ontological distinction
between objects and agents. Such systems could consequently never
be jealous (as being jealous involves other agents). This is a virtual machine
design constraint, not an implementation constraint.
Comparison with Other Work
There is now so much work on emotions in so many disciplines that a comparison
with alternative theories would require a whole book. Readers of
this volume will be able to decide which of the other authors have explicitly