What to Do

Start the demonstration by pressing the "Run" button. Move the mouse in order to keep either the upper or the lower filled cursor aligned with the stationary, unfilled target. The lower cursor is a passive screen object; the upper cursor is the output of a control system that is trying to keep another, invisible cursor in a varying reference state.

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What It's About

This tracking task shows that you can control the behavior of a control system just as well as you can control the behavior of an inanimate object if you are able to apply disturbances to a perception that control system is controlling. And you can do this even though the control system being controlled is autonomously varying it's intention (reference state) for the percpetion it is controlling.

The lower cursor is an inanimate object and it can easily be controlled; the upper cursor is the output of a computer control system that is controlling a perception which is disturbed by your mouse movements. The upper cursor shows what the computer control system is doing (what actions it is taking) to protect it's perception from your mouse disturbances.

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What To Notice

Once you have completed a tracking run (about one minute) you will see a graph of the results. The upper graph shows a time plot of the computer control system's reference for it's controlled perception and the state of that controlled perception. The lower graph shows a time plot of the position of the computer control system's output (upper cursor position) and your controlled perception (the lower cursor, if you were controlling it).

Notice how the computer control system is able to keep his controlled perception equal to his varying reference (top graph) even though you are controlling his output (lower graph) by disturbing his controlled perception with your mouse variations. Also notice that you are able to control the computer system's output even though his reference for his perception is not constant. You are able to vary your disturbances to the variable the computer system is controlling in just the way needed to bring the system's output to your reference for that output; you can control one aspect of the behavior of the computer control system (its output) without interfering with the computer control system's ability to control his perception.

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