Who Needs Emotions? The Brain Meets the Robot

206 robots
some cases and in other cases deliberative, i.e., mediated by a mechanism
that represents possible sequences of actions, compares them, evaluates them,
and makes selections on that basis before executing the actions.
We can distinguish sensors that act as need-sensors from those that act
as fact-sensors. Need-sensors have the function of initiating action or tending
to initiate action (in contexts where something else happens to get higher
priority) to address a need, whereas fact-sensors do not, though they can
modify the effects of need sensors. For most animals, merely sensing the fact
of an apple on a tree would not in itself initiate any action relating to the
apple. However, if a need for food has been sensed, then that will (unless
overridden by another need) initiate a process of seeking and consuming food.
In that case, the factual information about the apple could influence which
food is found and consumed.
The very same fact-sensor detecting the very same apple could also
modify a process initiated by a need to deter a predator; in that case, the
apple could be selected for throwing at the predator. In this case, we can say
that the sensing of the apple has no motivational role. It is a “belief-like” state,
not a “desire-like” state.
INFORMATION-PROCESSING ARCHITECTURES
The information-processing architecture of an organism or other object is the
collection of information-processing mechanisms that together enable it to
perform in such a way as to meet its needs (or, in “derivative” cases, could
enable it to meet the needs of some larger system containing it).
Describing an architecture involves (recursively) describing the various
parts and their relationships, including the ways in which they cooperate or
interfere with one another. Systems for which there are such true collections
of statements about what they would do to meet needs under various
circumstances can be described as having control states, of which the belieflike
and desire-like states mentioned previously (and defined formally below)
are examples. In a complex architecture, there will be many concurrently
active and concurrently changing control states.
The components of an architecture need not be physical: physical mechanisms
may be used to implement virtual machines, in which nonphysical structures
such as symbols, trees, graphs, attractors, and information records are
constructed and manipulated. This idea of a virtual machine implemented in
a physical machine is familiar in computing systems (e.g., running word processors,
compilers, and operating systems) but is equally applicable to organisms
that include things like information stores, concepts, skills, strategies,