From John A. 990307
Here are some further thoughts about controlled variables. I must say I'm
having a good time trying to think of various variables. As a doctor, the
first thing I want to know about a patient is, is he conscious, does he know
where and who he is? Then I want to know what is his pulse, blood pressure,
temperature, rate of breathing. The latter are all thermostats, metaphorically
speaking. e.g. the pulse gets too high his brain slows it down, if his
temperature gets above 98.6'' he begins to sweat, if too cold he shivers and
jumps around puts on a sweater. I then weigh him. His weight is a controlled
variable. If he gets too fat he eats less, or tries to; if too thin he eats
more. If he's hungry he eats, if he's full he doesn't eat. I ask him to stand
on one foot. His balance is a thermostat. If he starts to fall toward the
right he leans toward the left.
The first list of clinical observations: is he conscious? awake? oriented?
sane? are more difficult for me to describe as thermostats. but they probably
can be so described. Sanity, for example, depend on constant interaction with
the environment, viz. isolation tank experiments.
Bruce are we humans just a bunch of thermostats going around. How about
marriage, is that a thermostat? If it gets too hot we try to cool it
too cold , try to warm it up. How about employment? If a person produces more
he gets paid more. If a student answers more test questions correctly he gets
a higher academic mark. etc., etc. Can a market economy or a socialist
controlled economy be described as thermostats?
I believe there are everyday words which describe these metaphorical human
"give and take." "a friend in need is a friend indeed". "you scratch my back,
I'll scratch yours." "Doing your fair share" "Holding up your end."
as "responsibility," "autonomy,"" choice" defeat me.
If all the above is correct it still doesn't' tell me, as a doctor, what
about any of the thermostats malfunction. How do you fix a broken thermostat?
Do you need a prescriptive theory? Like BCT?
Bruce, or anyone else, are you with me in the above?
jappel2115.vcf (63 Bytes)
>From John Appel 990305
Bruce Gregory wrote:
> [From Bruce Gregory (990304 .0942 EST)]
> > > John A 990303
> > Please tell me what a "controlled variable" is. If possible do so in
> > everyday language. Also give some examples. And how does one
> > do research
> > on controlled variables?
> In most buildings the temperature is a controlled variable at least in
> the winter. In other words, the temperature in the building tends to
> remain at a constant level in spite of changes in the outside
> temperature. In you suspect that the temperature is being controlled,
> you might do research by opening a window and seeing if the temperature
> remains above that in the inside world. Stability of temperature under
> these conditions is evidence for the existence of a controlled variable.
> You probably can exceed the ability of the system to maintain a constant
> temperature by opening all the windows.
Thank you. I believe I now do understand what controlled variable means.
Also I understand how controlled variable is tested and proved. I'm less
sure I understand what theory is tested and proved in proving the variable.
I'll ponder it.
> This "loss of control" is what
> you see in your patients. You must guess at what they are trying to
> control. You test those guesses by making _small_ changes and observing
> whether they resist the change (open a window). If they do (the shiver,
> complain about temperature or, put on a sweater), you have identified a
> controlled variable. If they ignore the disturbance they are not trying
> to control their body temperature very strongly (with high gain).
I'll have to ponder this suggestion: Psychosis--insanity-- is equivalent to
losing control of temperature. This suggestion does resonate a little. But
still this leaves unexplained the nature of the variable. Could it be
sanity? Someone in csg, I forget who, suggested homeostasis. Control of
homeostasis is well known in medicine, of course. But here the idea of
mental homeostasis might apply. Maybe sanity is the variable. Or autonomy,
which enables a person to choose whether to submit to, or oppose control by
some one else. And the idea--anticipation of consequences of action--would
have to fit in somewhere. And further, how explain treatment and recovery?
I can do so with bct, but not using the thermostat model. Perhaps you can
tell me. Also I don't yet see how cause and effect can be avoided. Perhaps
the the element of the thermostat that responds to the lower temperature by
turning on the furnace "causes" the heat to increase.
Well, as you see, you've got me thinking .Thank you.
Univ. of Pennsylvania.