[From Bruce Abbott (970401.0830 EST)]
The following paper appeared in this month's issue of _Behavioral
Researcher_. I thought it would be of interest to CSGnetters.
Rocks as Control Systems
Hiam J. King
Quaker State University
Abstract
Six rocks of various sizes and shapes were tested for their ability to
control their position on a 4 X 6 foot table. The tests revealed, contrary
to expectation, that rocks are excellent control systems. It is concluded
that perceptual control theory (Powers, 1973), which was designed to account
for human and animal behavior, may have important applications that extend
beyond the realm of the animate.
Introduction
Perceptual control theory (Powers, 1973) asserts that living organisms are
in fact living control systems, which are organized so as to maintain their
inputs (perceptions) close to internally-specified reference values. These
reference values may be relatively fixed (as in the homeostatic control of
blood-sugar levels; Cannon, 1932) or may vary (as in servomechanisms, in
which the input is made to "track" or follow the reference). In either
case, deviations of the input from its current reference level produce an
action on the part of the system that tends to push the input back toward
the reference; thus, a characteristic of a control system is its ability to
counteract or resist disturbances to the input variable that otherwise would
tend to move the input away from its reference value.
Although control has been demonstrated in organisms as diverse as bacteria
and human beings, it has been thought that inert, non-living objects do not
exhibit this phenomenon, unless specifically designed to do so by human
engineers. However, this belief represents more an assertion of faith than
good science, as it has not to our knowledge been submitted to rigorous
test. The present study corrects this deficiency by examining the ability
of inanimate objects to control. To make this test as rigorous as possible,
I chose as subjects objects that seemed entirely unlikely to exhibit any
evidence of control, namely a set of six ordinary rocks of varying sizes and
shapes. Because one of the most notewothy characteristics of rocks is their
tendency to stay put, I chose to test for the rocks' ability to control
their position on the table.
Method
_Subjects_
The subjects were six rocks of varying shapes and sizes that were acquired
from a stream-bed in Clarion, PA. They weighed between 131 and 972 grams,
and had average diameters of between 2.3 and 11.6 cm. Whether the rocks
were sedimentary, metamorphic, or igneous was not determined.
_Apparatus_
The apparatus consisted of an ordinary 4 X 6 foot (121.9 X 182.9 cm) table,
which was carefully leveled using an accurate carpenter's level (Stanley
Co.), to prevent gravitational effects from biasing the results.
_Procedure_
Each rock was tested individually, in a randomly-determined order. The rock
to be tested was placed at the approximate center of the table and observed
for five minutes in order to assess the rock's tendency for spontaneous
movement. Then the rock was pushed against (by the investigator's right
index finger) from several directions and with varying force in order to
assess the rock's ability to resist being displaced from its current
position. When this external disturbance was removed, the rock was again
observed to determine whether it would then return to its former position on
the table.
Results
A surprisingly simple and reliable pattern of results emerged from testing.
None of the six rocks was observed to move during the initial period of
observation. When disturbances were applied, each of the rocks eventually
began sliding across the table in the direction of the applied force
(although the force required to start this action varied directly with the
size of the rock). Finally, when the disturbance was removed, each rock
remained where it had come to rest.
Discussion
Our initial impression was that the rocks had failed to demonstrate any
evidence of control over their positions on the table. However, after
giving the problem some thought, I realized that in fact the results were
completely consistent with the view that the rocks were indeed controlling
their positions, but in an unexpected way. The entire pattern of results
can be accounted for within a control-system framework if it is assumed that
rocks are at least two-level control systems. In this view, the lower-level
system controls the position of the rock as previously hypothesized.
However, the reference value for this system is determined by the output of
the upper-level system, which is controlling for _pleasing the
experimenter_! This upper-level system senses the force being exerted on
the rock by the experimenter's push, and varies the lower-level system's
reference level for position in such a way that the rock then moves in the
direction the rock senses that the experimenter wants it to go. This
accounts for why the rock stays where it is put, and moves in the direction
it is pushed.
The implications of this finding, if confirmed, are enormous. For one
thing, it suggests that even inanimate objects have desires and purposes and
will attempt to achieve them under proper conditions. The rocks tested
evidently were positively disposed toward the experimenter (perhaps because
he saved them from further wear by the action of water in the streambed),
but it would be premature to conclude that rocks in general hold this
attitude. For example, the falling rocks encountered along highways cut
through the sides of mountains may be attempting to get even with drivers
for disturbing their environment. Additional research will be required to
determine whether this is the case.
In our laboratory, we are already engaged in examining the range of this
phenomenon. Currently we are getting set up to determine whether ice cubes,
by sensing their surface temperatures, can infer the desire of the
experimenter to melt them, and act accordingly.
References
Cannon, W. B. (1932). _The wisdom of the body. New York: Norton.
Powers, W. T. (1973). _Behavior: The control of perception._ Chicago:
Aldine.