Who Needs Emotions? The Brain Meets the Robot

architectural basis of affect 239
response to a perceived threat, in a robot whose processing speeds are so great
that it needs no alarm mechanism. It is arguable, then, that only linguistic expression
(see Arbib, Chapter 12) is capable of conveying the vast majority of
tertiary emotions, whereas most current research on detecting emotions focuses
on such “peripheral” phenomena as facial expression, posture, and other
easily measurable physiological states.
THE NEXT STEPS
Emotions in the sense we have defined them are present in many control
systems, where parts of the control mechanism can detect abnormal states
and react to them (causing a change in the normal processing of the control
system, either directly through interruption of the current processing or
dispositionally through modification of processing parameters). Emotions
thus defined are not intrinsically connected to living creatures, nor are they
dependent on biological mechanisms; e.g., operating systems running on
standard computers have several emotions in our technical sense, although
they lack many of the detailed features of the sorts of emotion to which our
folk concepts are applied.
What is special about at least a subset of emotions so defined (compared
to other non-emotional control states) is that they (1) form a class of useful
control states that (2) are likely to evolve in certain resource-constrained
environments and, hence, (3) may also prove useful for certain AI applications
(e.g., robots that have only limited processing resources, which impose
severe constraints on the kinds of control mechanism that can be implemented
on them).
Useful affective control mechanisms are likely to evolve if there are many
evolutionary trajectories that, given various sets of well-specified initial conditions
and fitness functions, will lead to those control systems (e.g., Scheutz,
2001; Scheutz & Schermerhorn, 2002). A subset of those will be control
mechanisms that can produce emotional states suited to coping with emergencies
or unexpected situations as they occur in dynamic, unpredictable,
real-world environments.
It is not yet clear which of the more subtle and complex long-term
emotional states, such as grief, ambition, jealousy, infatuation, and obsession
with a difficult problem, are merely side effects of desirable mechanisms and
which are states that can be intrinsically useful in relation to either the needs
of individuals or the needs of a social group or species. Human aberrations
make it clear, however, that machines containing useful mechanisms are
capable of getting into highly dysfunctional states through the interactions
of those mechanisms. As machines become more human-like, we can expect