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3.3 Coordination and Control of Behaviors
While the learned behaviors are very complex, they can still be repre-
sented by innate releasing mechanisms. It is just that the releasers and
actions are learned; the animal creates the program itself.
Note that the number of categories suggests that a roboticist will have a spec-
trum of choices as to how a robot can acquire one or more behaviors: from
being pre-programmed with behaviors (innate) to somehow learning them
(learned). It also suggests that behaviors can be innate but require mem-
ory. The lesson here is that while S-R types of behaviors are simple to pre-
program or hardwire, robot designers certainly shouldn’t exclude the use
of memory. But as will be seen in Chapter 4, this is a common constraint
placed on many robot systems. This is especially true in a popular style of
hobby robot building called BEAM robotics (biology, electronics, aesthetics,
and mechanics), espoused by Mark Tilden. Numerous BEAM robot web sites
guide adherents through construction of circuits which duplicate memory-
less innate reflexes and taxes.
An important lesson that can be extracted from Lorenz and Tinbergen’s
INTERNAL STATE work is that the internal state and/or motivation of an agent may play a role
MOTIVATION in releasing a behavior. Being hungry is a stimulus, equivalent to the pain
introduced by a sharp object in the robot’s environment. Another way of
looking at it is that motivation serves as a stimulus for behavior. Motiva-
tions can stem from survival conditions (like being hungry) or more abstract
goals (e.g., need to check the mail). One of the most exciting insights is that
behaviors can be sequenced to create complex behaviors. Something as com-
plicated as mating and building a nest can be decomposed into primitives
or certainly more simple behaviors. This has an appeal to the software engi-
neering side of robotics.

3.3.1 Innate releasing mechanisms

Lorenz and Tinbergen attempted to clarify their work in how behaviors are
INNATE RELEASING coordinated and controlled by giving it a special name innate releasing mech-
MECHANISMS anisms (IRM). An IRM presupposes that there is a specific stimulus (either
internal or external) which releases, or triggers, the stereotypical pattern of
RELEASER action. The IRM activates the behavior. A releaser is a latch or a Boolean vari-
able that has to be set. One way to think of IRMs is as a process of behaviors.
In a computational theory of intelligence using IRMs, the basic black boxes
of the process would be behaviors. Recall that behaviors take sensory input
and produce motor actions. But IRMs go further and specify when a behav-