[From Rick Marken (2006.12.11.0945)]
It seems to me there are two classes of disturbance: (1) those that we are
consciously aware of and attend to as such and (2) those that are simply
compensated for in our behavior with no thought to disturbance as such.
Yes, and there are another two kinds of "disturbances": the change in qi resulting form the effect of a disturbance -- call it delta_qi -- and the disturbance variable itself -- d. In your example of walking on a ship in high seas, delta_qi would be the change in your perception of balance resulting from d, the pitching of the ship. You can be consciously aware or unconscious of delta_qi because delta_qi is a perception. You can also be consciously aware or unconscious of d, too, but only if it exists as a perception. But d is often unperceived. In you ship example, d -- the pitching of the boat -- can certainly be perceived, so you can be aware of it or not. But in many (most) situations d is unperceived, as in the compensatory tracking task. So you can't really be conscious or unconscious of d since it doesn't "exist" as far as you are concerned. All you can perceive (and therefore be aware of or not), in the compensatory tracking task, is delta_qi, which in that case is the perception of a change in the position of the cursor.
Is there any value in conceptualizing two classes of disturbance?
If the two classes are "consciously perceived" versus "not consciously perceived" (regardless of whether you are referring to a disturbance in the delta_qi or d sense) I think, yes, there _may_ be a difference between controlling with and without consciousness. I think both reorganization theory and Zen Buddhism suggest that control would be better when done unconsciously. I think Bill Powers has actually done some experiments that suggest that this is, indeed, the case.
Now, as to Bruce Nevin's distinction: Earlier, I used a sunlight example and
indicated that I had to squint (whether to continue driving safely or simply
to protect my eyes needn't detain us at this point). The sun, if I
understand Bruce Nevin's point, is the "source" of the disturbance. The
"disturbance" itself is the effect of the sun's rays on my retina. Do I
have that right?
Yes, though I think it's better to say that the "disturbance itself is the effect of the sun's rays on the perception under control" rather than on the retina. The perception is a function of aspects of the light on the retina. What aspect of the "sun's rays" constitutes a disturbance depends on what the controlled perception is. In you example, one controlled perception was the perceived overall brightness on the retina. That's qi and it's value varies as a function of the _intensity_ of the sun rays falling on the retina, the intensity of which are d. The value of qi also depends on the level of "squint", which is the output variable, o. So we can say that the magnitude of the controlled perception, qi, which is the brightness of light on the retina, depends on the intensity of the sun's rays, d, as well as on the level of squint, o: qi = d + o.
Best
Rick
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On Monday, December 11, 2006, at 05:10 AM, Fred Nickols wrote:
