Three Blind Men

[Rick Marken (920506 17:30)]

Well I have it on the highest authority (Gary Cziko -- net God)
that it would be OK to post my paper since it is within the
bounds of decency (20Kbytes). Indeed, I think it's damn near
that limit. I am posting it in the hopes of getting 1) helpful
comments -- be nice now and 2) suggestions about where it might
be worth trying to submit it for publication -- be even nicer.

Or, simply hit the 'n' key now cause here it comes:



The Blind Men and the Elephant:
Three Different Perspectives on the Phenomenon of Control

Richard S. Marken

  Abstract - Psychologists have described behavior as
1) a response to stimulation 2) an output controlled by
reinforcement contingencies and 3) an observable result of
cognitive processes. It seems like they are describing three
different phenomena but they could be describing one
phenomenon -- control -- from three different perspectives.
Control is like the proverbial elephant studied by the three
blind men; what one concludes about it depends on where
one stands. It is suggested that the best place to stand is
where one has a view of the whole phenomenon - be it
elephant or control.

  The behavior of living organisms (and some
artifacts) is characterized by the production of consistent
results in an unpredictably changing environment, a
phenomenon known as control (Marken, 1988). Control
can be as simple as maintaining one's balance on uneven
terrain or as complex as maintaining one's self-esteem in a
dysfunctional family. Control is a pervasive aspect of all
behavior yet it has gone virtually unnoticed in psychology.
What has been noticed is that behavior is a response to
stimulation, an output controlled by reinforcement
contingencies or an observable result of cognitive processes.
Each of these ways of describing behavior is what would be
expected if people were describing control from different
perspectives. The situation is similar to that of the the three
blind men who were asked to describe an elephant; the one
near the tail described it as a snake, the one near the leg
described it as a tree trunk and the one near the side
described it as a wall. These descriptions gave a true picture
of some aspects of the elephant, but a false picture of the
elephant as a whole. If behavior involves control then
psychology, too, has given a true picture of some aspects of
behavior but a false picture of behavior as a whole. To see
why this might be the case it is necessary to take a close look
at what it means to control.

Closed-Loop Control

  The basic requirement for control is that an organism
exist in a negative feedback situation with respect to its
environment. A negative feedback situation exists when an
organism's response to sensory input reduces the tendency
of that input to elicit further responding. Negative feedback
implies a closed-loop relationship between organism and
environment; sensory input causes responding that
influences the environmental cause of that input. It is hard to
imagine an organism that does not exist in such a closed-
loop situation because all organisms are built in such a way
that what they do affects what they sense. Eyes, for
example, are located on heads that move so that what the
eyes see depends on what the head does. To the extent that
what the head does depends on what the eyes see (and it
does, at least sometimes, as when the head turns in response
to an attractive passer-by) there is a closed loop; sensory
input causes responding (head movement) which affects the
cause of responding (sensory input). The feedback in this
loop must be negative because behavior is stable; it does not
normally exhibit the "run away" behavior that characterizes
positive feedback loops (such as the "feedback" from a
microphone that amplifies its own output).

  The fact that organisms exist in a closed negative
feedback loop means that two simultaneous equations are
needed to describe their relationship to the environment. The
first describes the effect of sensory input on responding (for
simplicity we will assume that all functions are linear and
that all variables are measured in the same units) so that

r = k.o (s*-s) (1),

where r is the response variable and s is the sensory input
variable (expressed as deviation from s* which is the value
of the input that produces no response -- or no change in
response -- from the organism). The multiplier, k.o, is the
linear organism function that transforms sensory input into
responding. The second equation, too often ignored by
psychologists, describes the effect of responding on sensory
input. For simplicity it is assumed that responding adds to
the effect of the environment so that

s = k.f (r)+ k.e (d) (2),

where r and d are the response and environmental variables,
respectively. These variables have independent (additive)
effects on the sensory input, s. The nature of the
environmental effect on sensory input is determined by the
environmental function, k.e. The feedback effect of
responding on the sensory cause of that responding is
determined by the feedback function, k.f.

  These two equations must be solved as a
simultaneous pair in order to determine the relationship
between stimulus and response variables in the closed loop.
The result is

r = k.o/(1+k.o k.f) s* - (k.o k.e)/(1+k.o k.f) d (3).

The organism function, k.o, transforms a small amount of
sensory energy into a huge amount of response energy (such
as when patterns of light on the retina are transformed into
the forces that move the head). In control engineering, k.o
is called the "system amplification factor" and it can be quite
a large number. With sufficient amplification (such that k.o

k.f and k.o >> 1) equation (3) simplifies to

r = s* - (k.e/k.f) d (4).

  Equation (4) describes the relationship between
environmental (stimulus) and response variables when on
organism is in a closed-loop, negative feedback situation
with respect to its environment. The result of being in such
a situation is that the organism acts to keep its sensory input
equal to s*, which is called the reference value of the input.
The organism does this by varying responses to compensate
for variations in the environment that would tend to move
sensory input away from the reference value; this process is
called control. What is remarkable about control is that
responses depend on environmental events, d, and not on
the sensory inputs, s, that are caused by these events. The
sensory inputs are cancelled out of equation (4) by the
amplifying effect of the organism on those inputs.
Responses also depend on the reference value for sensory
inputs, s*, but the value of s* is determined by properties of
the organism, not the environment. Thus, variations in s*
will appear to be spontaneous because they do not
necessarily correlate with other variables in the organism's

Three Views of Control

  All variables in equation (4), with the possible
exception of s*, are readily observable when an organism is
engaged in the process of control. The environmental
variable, d, is seen as a stimulus, such as a light or sound.
The response variable, r, is any measurable result of an
organism's actions, such as a bar press or a spoken word.
The reference value for sensory input, s*, is difficult to
detect because an observer cannot see what an organism is
sensing. The value of s* can be measured in terms of the
environmental variables (it corresponds to that value of d that
results in no corrective response by the organism). But it
would be hard to imagine why someone would even try to
make such a measurement unless he or she knew that the
organism was controlling its sensory input. In fact, just the
opposite is the typical assumption -- that the organism is
controlled by its sensory input.

  The reference value for sensory input, s*, is the
central feature of control since everything an organism does
is aimed at keeping its sensory inputs at their reference
values. Because the reference value is difficult to observe it
will not be obvious to an observer that an organism is
engaged in the process of control. What will be obvious is
that certain variables, particularly the environmental and
response variables, and the relationship between those
variables, will behave as described by equation (4). Thus,
equation (4) can be used to show what control might look
like if one did not know that it was occurring. It turns out
that there are three clearly different ways of looking at
control depending on which aspect of the behavior described
by equation (4) one attends to.

1. The stimulus - response view. This view of control sees
behavior as a direct or indirect result of input stimulation.
Equation (4) shows that behavior will look this way when
the reference value for stimulus input is a constant; for
simplicity assume that it is zero. Then

r = - (k.e/k.f) d (5).

It looks like variations in an environmental stimulus, d,
cause variations in the response, r. This is what we see in
so-called "reflex" behavior, such as the pupillary response,
where changes in a stimulus variable (such as illumination
level) lead to changes in a response variable (such as pupil
size). Of course, this relationship between stimulus and
response is precisely that which is required to keep a sensory
variable (sensed illumination) at a fixed reference value, s*.

  One's inclination when looking at an apparent
relationship between stimulus and response is to assume that
the nature of that relationship depends on characteristics of
the organism. Equation (5) shows, however, that when an
organism is engaged in control, this relationship depends
only on characteristics of the environment (the functions k.e
and k.f); the organism function, k.o, that relates sensory
input to response output, is rendered completely invisible by
the negative feedback loop. This characteristic of the process
of control has been called the "behavioral illusion" (Powers,

2. The reinforcement view. This view of control sees
behavior as an output that is shaped by contingencies of
reinforcement. A reinforcement contingency is a rule that
relates outputs (like bar presses) to inputs (reinforcements);
in equation (4) this contingency is represented by the
feedback function, k.f, that relates responses to sensory
inputs. Equation (4) shows that it would look like the
feedback function controls responses when s*, d and k.e are
constants, as they are in the typical operant conditioning
experiment. In these experiments, s* is the organism's
reference value for the sensory effects of the reinforcement;
it is kept constant (and large) by maintaining the test animal
at a fixed proportion of its normal body weight. The
environmental variable, d, is the reinforcement, which, if it
is food, is a constant size and weight. The sensory effect of
a reinforcement can be assumed to be directly proportional to
its size and weight, making k.e = 1. So, for the operant
conditioning experiment, equation (4) can be written as

r = S* - 1/k.f (D) (6)

where S* is the constant (and possibly very large) reference
value for sensed reinforcement and D is the constant value of
the reinforcement itself.

  The only variable in equation (6) is the feedback
function, k.f, which defines the contingencies of
reinforcement. One simple contingency is called the "ratio
schedule" in which the organism receives a reinforcement
only after a certain number of responses. The term "ratio"
refers to the number of responses required per reinforcement
. So a "ratio 10" schedule is one in which the organism must
make ten responses in order to get one reinforcement. It is
regularly found that increases in the ratio lead to increases in
rates of responding. Such a result is predicted by equation
(6) which can be seen by letting k.f equal the ratio value.
Increases in the ratio, k.f, lead to increases in responding, r.
This relationship exists because the organism is controlling
sensed reinforcement; responding varies appropriately to
compensate for changes in the reinforcement contingency so
that sensed reinforcement is kept at a constant reference

3. The cognitive view. This view of control sees behavior
as a reflection or result of complex mental plans or
programs. This kind of behavior is seen when people
produce complex responses (such as spoken sentences,
clever chess moves or canny investment decisions)
apparently spontaneously; there is often no visible stimulus
or reinforcement contingency that can be seen as the cause of
this behavior. Cognitive behaviors are most obvious when
environmental factors (such as stimulus variables and
environmental and feedback functions) are held constant.
When this is the case, equation (4) becomes

r = s* + K (7).

where K = (k.e/k.o)D, a constant.

  Since s* is typically invisible, equation (7) shows
that there will appear to be no obvious environmental
correlate of cognitive behavior. An observer is likely to
conclude that variations in r are the result of mental
processes -- and, indeed, they are. But it is actually
variations in s*, not r, that are caused by these processes;
variations in r being the means used to get sensory inputs
equal to s*. Thus, chess moves are made to keep some
sensed aspect of the game at its reference value. When the
environment is constant, r (the moves) may be a fair
reflection of changes in the reference value for sensory
input. However, under normal circumstances r is only
indirectly related to s*, variations in r being mainly used to
compensate for variations in the environment that would tend
to move sensory input from the reference value, s*.

Looking at the Whole Elephant

  The blind men never got a chance to look at the
whole elephant but if they had they would have instantly
understood why it seemed like a snake to one, a tree trunk
to another and a wall to the third. Psychologists, however,
can take a look at control and see why behavior looks like
different phenomena from different perspectives. What is
common to the three views of behavior discussed in this
paper is the reference for the value of sensory input, s*.
Organisms behave in order to keep sensory inputs at these
reference values (Powers, 1973). They respond to
stimulation in order to keep the sensory consequences of this
stimulation from moving away from the reference value; so it
appears that stimuli cause responses. They adjust to changes
in reinforcement contingencies by responding as needed in
order to keep the sensory consequences of reinforcement at
the reference value; so it appears that contingencies control
responding. And they change their responding in order to
make sensory input track a changing reference value for that
input; so it seems like responding is spontaneous.

  What appear to be three very different ways of
describing behavior suddenly are seen as legitimate ways of
describing different aspects of one phenomenon -- control. It
also becomes possible to make sense of all aspects of the
organism's behavior once one discovers the sensory inputs
that are being controlled. Controlled sensory inputs are
called controlled variables and s* is the reference value for
controlled variables. There are methods, based on control
theory, that can be used to determine what sensory variables
are being controlled by an organism at any time (Marken,
1989). These methods make it possible to take off the
blindfolds and see the whole elephant -- the phenomenon of


Marken, R. S. (1988) The nature of behavior: Control as
fact and theory. Behavioral Science, 33, 196- 206.

Marken, R. S. (1989) Behavior in the first degree. In W.
Hershberger (Ed.) Volitional Action, Elsevier Science
Publishers: North-Holland

Powers, W. T. (1973) Behavior: The control of perception.
Chicago: Aldine

Powers, W. T. (1978) Quantitative analysis of purposive
systems: Some spadework at the foundations of scientific
psychology. Psychological Review, 85, 417-435


Richard S. Marken USMail: 10459 Holman Ave
The Aerospace Corporation Los Angeles, CA 90024
(310) 336-6214 (day)
(310) 474-0313 (evening)