Page 100 - Introduction to AI Robotics

Dominance of one (winner take all): you’re hungry and sleepy. You do one
DOMINANCE 3.4 Perception in Behaviors 83
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 differ-
ent mechanisms for conflicting behaviors are employed. Clearly, there’s no
one method. But it does emphasize that a roboticist who works with be-
haviors 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.

3.4 Perception in Behaviors

While Lorenz and Tinbergen’s work provides some insights into behaviors,
it’s clear that behaviors depend on perception. Ulrich Neisser, who literally
created the term “cognitive psychology” in his book, Cognition and Reality,
argued that perception cannot be separated from action. 109 As will be seen
in this section, J.J. Gibson, a very controversial cognitive psychologist, spent
his career advocating an ecological approach to perception. The ecological
approach is the opposite of the top-down, model-based reasoning about the
environment approach favored by psychologists, including Neisser. Inter-
estingly enough, Neisser took a position at Cornell where J.J. Gibson was,
and they became close colleagues. Since then, Neisser has spent significant
time and thought trying to reconcile the two views based on studies; this has
led to his identification of two perceptual systems.

3.4.1 Action-perception cycle

ACTION-PERCEPTION The action-perception cycle illustrates that perception is fundamental to any in-
CYCLE telligent agent. A simple interpretation of the cycle is: When an agent acts, it
interacts with its environment because it is situated in that environment; it is
an integral part of the environment. So as it acts, it changes things or how it
perceives it (e.g., move to a new viewpoint, trigger a rock slide, etc.). There-
fore the agent’s perception of the world is modified. This new perception is