6.1.7. Degrees of motivation and reactiveness
“We have to break things, but then we have to find out what to do with the pieces”
—Mafalda
In these experiments, we modified the values of the parameters ", (, and N of BeCA;
in order to observe how motivated or reactive is the behaviour of an animat depending on these
parameters. Some of the adjustments of these parameters can be seen as lesions in different
mechanisms of BeCA.
We used for all experiments an initial environmental state as the one shown in Figure
42. The animat has little fatigue, much thirst, and some hunger. There are food sources near
him, but the water sources are distant and the animat cannot perceive them at this stage. The
BVL’s interface allows the easy loading of this initial state for each experiment.
First, we took values of "=0.8, (=0.0, and N=1.0. These are the default values used in
the BVL. The behaviours executed by the animat can be appreciated in Figure 43. Since the
predominant need was thirst, the animat began to explore in the search of water, in spite of
perceiving food sources. When he perceived a water source, he approached it, and drank until
his thirst was satiated. After this, he approached a food source, and satiated his hunger by
eating. These behaviours were motivated by the internal states of the animat.
Figure 42. Initial state of the experiments. Figure 43. Behaviours executed with "=0.8, (=0.0,
and N=1.0.
For the next experiment, we took values of "=0.0, (=0.0, and N=1.0. Since the internal
and external signals are being combined multiplicatively (as it can be seen in expression (7)),
the animat will need to perceive the water before the respective behavioural column may win
the competition in the motivational node. So, since the animat was perceiving food and was
hungry, he approached it and ate until his hunger was satiated. After this, he wandered until
he finally perceived the water source, approached it, and satisfied his thirst by drinking it; as
shown in Figure 44. These behaviours are less motivated, since the animat cannot execute the
explore behaviour, and any internal need can fire its behaviour only if a corresponding external
stimulus is perceived. This also affects the animat’s survival performance, because he will need
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