[From Rick Marken (970911.1812)]
Bruce Abbott (970911.1855 EST)
You could knock me over with a feather.
That's how I felt when I first learned the difference
between a cause - effect and a control system. Heavy, eh?
All this time I've thought that a sufficient drop in room
temperature relative to the thermostat's setpoint leads to
closure of the thermostat's contacts, thus switching on the
furnace, and that the raising of the room's temperature as a
result of the heating action of the furnace causes the contacts
to pull with increasing force against the magnetic attraction
that is holding them together, until sufficient force develops
to pull the contacts apart (at the setpoint temperature),
thus turning the furnace off. It ain't so?
As far as it goes. But all this happens in a closed loop. So
room temperature is both a cause _and_ and an effect at the
same time. You really should try the demo. When you monitor
the relationship between system input (the presumed "cause" of
output) and system output (the presumed "effect" of input) you
find a very low or (in many cases) _no_ relationship at all.
Cause-effect should be made of terner stuff.
Things are not what they seem when they occur in a closed loop.
But all these myteries are summarized by one simple mnemonic:
behavior is the control of perception.
P.S. You should love me unconditionally -- I'm a regular Teddy bear.
I prefer Koalas;-)
But my little reference to "Maybe I'm Amazed" made me think of
something that's a lot more fun to do than trying to get you to
understand the difference between a cause-effect and a control
system: think of songs with PCT themes. For example, I recently
heard "You cain't always git wha tchu waant" (Stones spelling;-)
and realized it was a song about the reorganization system
("but if you try some time, you jus might find, you jus might
find, you get wha tcha need"). And then I quickly thought of
the perfect song for behaviorism: "Like a rock". Anybody got
one for model-based control?
Richard S. Marken Phone or Fax: 310 474-0313
Life Learning Associates e-mail: firstname.lastname@example.org