In a complex dynamic world, an artificial fish should have some persistence in its behavior, especially in its intentions, otherwise it will tend to dither, perpetually changing its mind. Basic persistence in the behaviors is modeled implicitly by the intrinsic ranking (prioritization) between them, the continuity in the mental state variables, and the constancy of the habits. For instance, the collision avoidance behavior precedes all other behaviors and once invoked, will only terminate when the collision is cleared. Once the mental state of hunger is high enough to activate the feeding behavior, the continuity in H (in particular the internal urge component) ensures that the activation level will not drop abruptly until the fish succeeds in taking more food. However, special attention needs to be paid to the maintenance of persistence in the case when an ongoing behavior is interrupted temporarily. In our case, there are two possible situations where an ongoing behavior may be interrupted: it may be interrupted by a behavior higher in the priority hierarchy triggered by some event or by an opportunity-triggered behavior.
|Xiaoyuan Tu||January 1996|