Concurrent behaviors

Concurrent behaviors

An important point from the examples with the IRMs is that behaviors can,
and often do, execute concurrently and independently. What appears to be a
fixed sequencemay be the result of a normal series of events. However, some
behaviorsmay violate or ignore the implicit sequence when the environment
presents conflicting stimuli. In the case of the parent agent, fleeing a predator
was mutually exclusive of the feeding, nursing, and sleeping behaviors.
Interesting things can happen if two (or more) behaviors are released that
usually are not executed at the same time. It appears that the strange interactions
fall into the following categories:
 Equilibrium (the behaviors EQUILIBRIUM seem to balance each other out): Consider feeding
versus fleeing in a squirrel when the food is just close enough to a person
on a park bench. A squirrel will often appear to be visibly undecided as
to whether to go for the food or to stay away.

 Dominance of one (winner take DOMINANCE all): you’re hungry and sleepy. You do one
or the other, not both simultaneously.
CANCELLATION  Cancellation (the behaviors cancel each other out): Male sticklebacks (fish)
when their territories overlap get caught between the need to defend their
territory and to attack the other fish. So the males make another nest!
Apparently the stimuli cancels out, leaving only the stimulus normally
associated with nest building.
Unfortunately, it doesn’t appear to be well understood when these different
mechanisms for conflicting behaviors are employed. Clearly, there’s no
one method. But it does emphasize that a roboticist who works with behaviors
should pay close attention to how the behaviors will interact. This
will give rise to the differences in architectures in the Reactive and Hybrid
Paradigms, discussed in later chapters.