3.7. Modelling Motivated Behaviours
“When ruling, rule yourself beautifully”
—Thales of Miletus
Motivated behaviours are those that by necessity require an internal state in order to be
executed (Manning, 1979; McFarland, 1981). That is to say, unlike reflex and reactive
behaviours, which show a rigid dependence of external stimuli, motivated behaviours are
controlled mainly by the internal state of the animal. For example, that an animal executes the
consummatory behaviour drink water depends not only on the presence of the external stimulus
water, but also on the internal need thirst. The absence of a stimulus might also be itself an
external stimulus capable of triggering a motivated behaviour. For example, the exploratory
behaviour in animals is a motivated behaviour, exhibited when the external signal appropriate
for the actual internal need is not present in the surrounding environment. Motivation is hence
a class of internal process that produces changes in the behaviour (McFarland, 1981).
Motivated behaviours are commonly characterized by: sequencing of component behaviours
in time, goal-directedness, spontaneity, changes in responsiveness, persistence in the execution
of behaviours, and several types of learning (Kupfermann, 1974; Beer, 1990).
Motivated behaviours are modelled in our BPS by incorporating a third layer over the
two previous ones. The creation of this third layer can be seen as a process of improvement and
refinement of the node related with the processing of external signals and of the node
responsible for processing of internal signals or motivations.
The process of improvement and refinement of the node related with the processing of
external signals includes the definition of three new blackboard levels: Consummatory
Preferents, Drive/Perception Congruents and Potential Actions, the refinement of internal
behaviours perceptual persistence and external behaviour selector, the definition of two new
internal behaviours: attention to preferences and reactive response inhibition, and the further
definition of the communication mechanisms receptor and transmitter. On the other hand, the
node responsible for processing internal signals will grow functionally and structurally from the
inclusion of the following components: three new blackboard levels, External Perceptions,
Intero/Extero/Drive Congruents and Drive; the intero/extero/drive congruence and consummatory
preferences selector internal behaviours that carry out the processing of internal signals, and the
communication mechanisms receptor and transmitter. We will begin the construction of this
layer improvement and refinement of the first node, assuming that it receives signals coming
from the node related with the internal states, which indicates the internal need that should be
satisfied.
At the Consummatory Preferents level, signals coming from the node responsible for
the processing of internal signals are recorded. These signals indicate which internal need
should be satisfied. The signals placed in the Drive/Perception Congruents level are derived
from the combination of signals recorded at the Perceptual Persistents and the Consummatory
Preferents levels. If a signal has been recorded at the Potential Actions level, then one of the
two following things will occur: this signal will reinforce the external behaviour firing, initiated
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