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4.2 Attributes of Reactive Paradigm

Figure 4.3 S-A organization of the Reactive Paradigm into multiple, concurrent be-
haviors.

havior’s perceptual schema, which can do as little or as much processing
as needed to extract the relevant percept. If a computationally inexpensive
affordance is used, then the sensing portion of the behavior is nearly instan-
taneous and action is very rapid.
As can be seen from the previous chapter on the biological foundations of
the reactive paradigm, behaviors favor the use of affordances. In fact, Brooks
was fond of saying (loudly) at conferences, “we don’t need no stinking rep-
resentations.” It should be noted that often the perceptual schema portion of
the behavior has to use a behavior-specific representation or data structure
to substitute for specialized detectors capable of extracting affordances. For
example, extracting a red region in an image is non-trivial with a computer
compared with an animal seeing red. The point is that while a computer pro-
gram may have to have data structures in order to duplicate a simple neural
function, the behavior does not rely on any central representation built up
from all sensors.
In early implementations of the reactive paradigm, the idea of “one sensor,
one behavior” worked well. For more advanced behaviors, it became useful
to fuse the output of multiple sensors within one perceptual schema to have
increased precision or a better measure of the strength of the stimulus. This
type of sensor fusion is permitted within the reactive paradigm as long as
the fusion is local to the behavior. Sensor fusion will be detailed in Ch. 6.