[From Bruce Abbott (981024.0900)]
I've begun to look into the literature on what are called "adjusting" or
"titrating" schedules. There are different types, but as an example, in one
study the apparatus incremented at a constant rate the intensity of
footshocks that were being delivered to a rat. Lever-pressing decremented
the shock intensity, and the rat could maintain the shock at any given
intensity by adjusting its rate of responding so as to bring the intensity
down (or up) and then simply match the increment rate to keep it there.
It's like walking down an "up" elevator. Surprisingly, the rats often
allowed the shock to reach an intensity that was clearly aversive to them
before producing a quick series of presses that worked the intensity back
down. No attempt was made to apply control theory to the data (which were
reported in the early 60s).
There is also published work on "behavioral regulation," which does not mean
regulation of behavior, but regulation by means of behavior. I've got to
visit the library to get a copy, but I did locate a study of
"thermoregulation" published many years ago in _Science_. There was also a
JEAB article in which a rat controlled the temperature of a water bath in
which it was partly emersed. There were two levers which acted like
Alice-in-Wonderland's two pills -- pressing one made the water stream
entering the chamber hot, pressing the other made it cold. By alternating
in the right way on the two keys, the rat could achieve a mixture that was
stable at any temperature between the extremes. Lo and behold, the rat kept
the water temperature close to its normal body temperature.