Game Development Reference
In-Depth Information
Figure 8.1
Simple feedback between two agents.
Feedback and Control
The study of complex systems is beyond the scope of this topic, but some of the
basic ideas from feedback and control systems can be illuminating. Aside from
the nuclear reactor example in which the atoms are destroyed, the actors in our
examples can act upon the actions in others that were triggered by the original
actor. ''I do something, you react to it, and then I react to you.'' This is known as
feedback and is shown in Figure 8.1.
Figure 8.1 has been simplified to show only the feedback. Both agents could have
other inputs. Both agents are free to decide what they do with any of the inputs,
including ignoring some or all of them. We will ignore those complexities as
much as we can. Timing and reinforcement are the key properties of feedback
that we need to examine.
In Figure 8.1, if the reaction of Agent A to feedback is to do more of what it did in
the first place, this is known as positive feedback . If left unchecked, positive
feedback results in chaos or system failure. Reactors melt, bison stampede at full
speed into places where going slow or perhaps turning might be prudent, and
children act out in ever more outrageous ways. Of course, not all positive
feedback is bad; in fact, positive feedback is one of the ways that good ideas get
turned into innovation. ''That's a great idea! We should do that!'' is positive
In Figure 8.1, if the reaction of Agent A to feedback is to do less of what it was
doing, we call it negative feedback . Your intuitive ideas about positive and
negative feedback are probably correct; feedback and control theory examine
them in exacting detail. Negative feedback can also be good or bad. ''I'd love to
go boating, but there are small craft warnings out,'' is probably wisdom. ''Great
idea, none of us has time for it,'' has prevented countless innovations from
becoming reality. Also called dampening , negative feedback is required to keep
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