[from Jeff Vancouver 980514.15:45 EST]
Assuming for the moment that I am actually controlling for a perception of
"getting it right in the eyes of PCT" I submit for input the following
changes to my chapter on self-regulation. This is not be any means the
only changes I am making or that are relevant to PCT. But it is in an area
that has troubled me for some time. So I thought I would seek input (as it
is not continuous or available without some action on my part).
I am writing about the effects of lag on control systems. I have described
a widget maker (widgets are our generic word for product) who controls the
degree to which her shelves are stocked with widgets. She makes widgets to
keep her perception of the shelves at the level "full of widgets."
Specifically, I say:
"In the maintenance context, the widget maker might monitor the state
of the shelves in her store. She might have a goal related to keeping the
shelves full. As customers purchase widgets, she must make more, but only
enough, to fill the shelves. That is, as the customers disturb the
variable (i.e., emptiness of shelves), the widget maker acts to return the
state of the shelves to her desired state for them (i.e., full)."
Sometime later in the chapter I attempt to describe lag and the difference
between PCT and Ashby's control description. I say:
"The other factor, lag, reflects the speed at which the cybernetic unit
reduces discrepancies (Deutsch, 1966). Lags occur in the environmental side
and the system side of control systems. Within hierarchical control
systems, differences in lag are required to prevent chaos (Powers, 1973).
Lower-level units must operate more rapidly than higher-level units.
Otherwise, higher-level units will change the level of goals in lower-level
units before the lower-level units attain the previous goal values.
Meanwhile, Ashby (1956) argued that complex systems are able to anticipate
disturbances and hence prepare or act before the perception of the current
state deviates from the desired state. This is particularly important when
lags in the environment preclude the ability of the system to maintain a
variable on-line (i.e., in real time). For example, our widget maker might
develop a clever advertising scheme. Expecting that the advertising will
lead to a run on widgets, she builds an extra supply of widgets so that she
does not run out before being able to make more.
"Although lag is central to PCT, the description of control systems acting
on anticipated discrepancies differs somewhat dramatically from PCT. In
PCT, compensations for lags can occur as the system develops experience
with the variable of interest. Hence, initially our widget maker will not
anticipate the effect of advertising on the state of the shelves in her
store. However, with experience, she will develop a control system that
monitors the level of her supplies. That control system normally has a
goal of zero. Yet, when a higher-level control system perceives a new ad
campaign, it will change the goal from zero to some number that is a
function of the amount of error in the higher-level control system. The
higher-level control system may be monitoring profit. Whenever our widget
maker perceives that profits are lower than desired, her sets a goal of
developing an advertising campaign and creating a supply of widgets."
I also changed a section which disturbed a perception of Rick's (3/30).
Here is the new wording.
"Powers highlighted the central role of behavior as a means of keeping a
perception in line with a fixed or varying goal. Further he recognized
that behavior is a problematic focus of attention for researchers because
of the system properties of equifinality and equipotential."
I am also changing some language that disturbed perceptions controlled by
Mary. The changes resulted in eliminating words that created false
impressions. I think they were straightforward changes so I will not post
them here. However, I suspect I will have more to run by this group soon.
So Rick, Bill, Mary, whoever, does this seem to be on the mark (does not
disturb any perceptions)?
Thanks in advance for any comments.
Sincerely,
Jeff