[From Bill Powers (960813.1430 MDT)]
Bruce Abbott (960813.1130 EST) --
Following up your references to Skinner's _Cumulative Record_ I got out
my old copy (1961 edition) and found more interesting stuff.
At the University of Michigan in the spring of 1940 the capacity of
the pigeons to steer toward a target was tested with a moving
hoist. The pigeon, held in a jacket and harnessed to a block, was
immobilized except for its head and neck. It could eat grain from a
dish and operate a control system by moving its head in the
appropriate direction. Movement of the head operated the motors of
the hoist. The bird could ascend by lifting its head, descend by
lowering it, and travel from side to side by moving appropriately.
The whole system, mounted on wheels, was pushed across a room
toward a bull's-eye on the far wall. During the approach the pigeon
raised or lowered itself and moved from side to side in such a way
as to reach the wall in position to eat grain from the center of
the bull's-eye. The pigeon learned to reach any target within reach
of the hoist, no matter what the starting position and during
fairly rapid approaches.
A little later --
The General Mills engineers also built a simulator (Figure 4) -- a
sort of Link trainer for pigeons -- designed to have the steering
characteristics of the Pelican [a winged glider, not a bomb], in so
far as those had been communicated to us. Like the wing-steered
Pelican, the simulator tilted and turned from side to side. When
the three-bird nose was attached to it, the pigeons could be put in
full control -- the "loop could be closed" -- and the adequacy of
the signal tested under pursuit conditions. Targets were moved back
and forth across the far wall of a room at prescribed speeds and in
given patterns of oscillation, and the tracking response of the
whole unit was studied quantitatively.
I recommend to all PCTers that they read the whole article. It
demonstrates Skinner's thoroughness as an experimenter, his cleverness,
and his absolute blindness to the significance of what he was finding as
he interacted with real control-system engineers. You'll note that in
the above excerpt, he refers freely to the pigeon as a controlling
agent, adjusting its actions as necessary to cause a predetermined
result to occur. But this experience made not the slightest impression
on his basic concept of how organisms work.
Nor did he modify his experimental approach. In the first excerpt above,
the pigeon is actually operating in a basically analog situation,
continuously varying the position of the hoist to keep the target
approaching. But in the Pelican control system design, Skinner went back
to what he was comfortable with -- pigeons pecking. He did this despite
having already found a far more elegant design, much better suited to
the task. He could have used the pigeon's head movements to operate
potentiometers and obtain continuous control of the position of the
target. The pigeon could simply have held the target centered, its head
movements operating (through servo boosters) the control surfaces of the
glider -- the sort of task that a pigeon already knows all about,
although it would have to learn a new means of acting to make its
perceptions look right for flying to a target. All this would have been
easy to do with existing technology. Of course the military might not
have liked the idea that all it takes to fly a weapon of war is the
brain of a pigeon.
I think it was in the 1960s that I wrote to Skinner telling him about a
control theory model of behavior. His reply was terse -- he didn't
believe that control theory had anything to offer to the experimental
analysis of behavior. I'm sure I had read the Pelican article by that
time. But if so, it didn't occur to me to remind him of it.
I feel sure that Skinner's rejection of control theory came about not so
much in spite of his experiences with real control systems and control
engineers, but because of them. He was completely committed to the idea
that the environment is the ultimate controller of behavior -- yet it
must have been obvious to him that none of the objects in the
environment of the pigeons (other than himself and colleagues) had any
capacity to control in the same way the pigeons were doing it. He was on
the very brink of discovering PCT, and turned his back on it -- years
before Norbert Wiener et. al. came along.
In mitigation, I think it's clear that Skinner ran afoul (or is that
afowl?) of the "modern control engineers" of his time. At a hearing
where he presented his case to the top scientists in the field, one
observer objected that the system would hunt wildly and lose the target.
Fortunately, another scientist was present who had seen the
simulator performing under excellent control and who could confirm
our report of the facts. But reality was no match for mathematics.
I wonder to what extend plain old bitterness, well-justified, might
account for Skinner's abandonment of the concepts of control theory.
On a wall in my maternal grandmother's house there hung an embroidered
motto:
Convince a man against his will --
He's of the same opinion still.
···
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Best,
Bill P.
