On the next higher level are the networks of sensory-motor skills and
habits -- such as touch-typing or driving a car, which are performed more
or less mechanically, and do not require the attention of the highest
centres -- unless some disturbance throws them out of gear. Driving a
car is a routine which includes, among its 'rules of the game', stepping
on the brake pedal when there is an obstacle ahead. But on an icy road
braking can be a risky affair, the steering wheel has a different feel,
and the whole strategy of driving must be altered -- transposed into
a different key, as it were. After a while this, too, may become a
semi-automatic routine; but let a little dog amble across the icy road
in front of the driver, and he will have to make a 'top-level decision'
whether to slam down the brake, risking the safety of his passengers,
or run over the dog. And if, instead of a dog, the jaywalker is a child,
he will probably resort to the brake, whatever the outcome. It is at this
level, when the pros and cons are equally balanced, that the subjective
experience of freedom and moral responsibility arises.
Feedbacks and Homeostasis
But the ordinary routines of existence do not require such moral
decisions, and not even much conscious attention. The physiological
processes breathing, digestion, etc. -- look after themselves: they are
self-regulating. And so are most routine activities: walking, bicycling,
driving a car. The principle of self-regulation is in fact fundamental to
the hierarchic concept. If a holon is to function as a semi-autonomous
sub-whole, it must be equipped with self-regulatory devices. In other
words, its operations must be guided, on the one hand, by its own
fixed canon of rules and on the other had by pointers from a variable
environment. Thus there must be a constant flow of information concerning
the progress of the operation back to the centre which controls it; and
the controlling centre must constantly adjust the course of the operation
according to the information fed back to it. This is the principle of
"feedback control".* The principle is old -- James Watt had already
used it in his steam-engine to keep its velocity steady under varying
conditions of load. But its modern applications, under the name of
"cybernetics", have been remarkably successful in the most varied fields,
from physiology to computing machines -- another case of pulling lively
rabbits out of an old hat.
* Feedback is generally defined as the coupling of the output to
the input.
The simplest illustration of feedback control is thermostatically
regulated central heating. You set the thermostat in the living room
at the desired temperature. If the temperature falls below it, the
thermostat activates an electrical circuit, which in turn increases the
rate of burning in the heating plant. If it gets too hot in the room,
the opposite process takes place. The plant in the cellar controls the
temperature in the room; but the information sent back to it by the
thermostat in the room corrects the function of the plant, and keeps it
steady. Another obvious example is the servo-mechanism which keeps a ship
on a steady course by automatically counteracting any deviation from it.
Hence the term 'cybernetics' -- from the Greek
cybernitos
= helmsman.
The living organism is also controlled by a thermostatic device, which
keeps its temperature at a stable level -- with variations rarely
exceeding one centigrade, more or less. The seat of the thermostat is
in the hypothalamus, a vital structure in the brain-stem. One of its
functions is to maintain homeostasis -- a steady body temperature, pulse
rate, and chemical balance of body fluids. The microscopic thermostat
in the brain-stem has been shown to react to local temperature changes
of a hundredth of a centigrade. When the temperature in its immediate
vicinity -- on the ear-drum -- exceeds a critical level, sudden sweating
sets in. Conversely, when the temperature falls, the muscles automatically
start to shiver, converting energy into heat. Other 'homeostats' (a term
coined on the analogy of the thermostat) control other physiological
functions, and keep the organism's
milieu interieur
-- its 'inner
environment' -- on a stable level.
We thus have precise evidence for self-regulating mechanisms operating
at the basic levels of the hierarchy. The word 'homeostasis' was
coined by Walter B. Cannon, the great Harvard physiologist, who had a
clear grasp of its hierarchic implications. He wrote that homeostasis
liberates the organism 'from the necessity of paying routine attention
to the management of the details of bare existence. Without homeostatic
devices, we should be in constant danger of disaster, unless we were
always on the alert to correct voluntarily what normally is corrected
automatically. With homeostatic devices, however, that keep essential
bodily processes steady, we as individuals are free from such slavery --
free to . . . explore and understand the wonders of the world about us,
to develop new ideas and interests, and to work and play, untramelled
by anxieties concerning our bodily affairs.' [2]
Self-regulating devices are found not only on the visceral level;
they operate on every level of an organism's activities. A boy riding
a bicycle, a tightrope-walker balancing himself with his bamboo stick,
are perfect examples of kinetic homeostasis. But each depends on constant
kinesthetic feedback -- on sensations reporting the movements, tensions,
postures of his own body. When the feedback stops, homeostasis breaks
down.
The next quotation is from Norbert Wiener, who coined the term
'cybernetics', and put the concept of feedback on the map:
A patient comes into a neurological clinic. He is not paralysed,
and he can move his legs when he receives the order. Nevertheless,
he suffers under a severe disability. He walks with a peculiar,
uncertain gait, with eyes downcast, on the ground and on his legs.
He starts each step with a kick, throwing each leg in succession in
front of him. If blindfolded, he cannot stand up, and totters to
the ground. What is the matter with him?
. . . [He] suffers from tabes dorsalis. The part of the
spinal cord which ordinarily receives sensations has been damaged
or destroyed by the late sequelae of syphilis. The incoming messages
are blunted, if they have not totally disappeared. The receptors in
the joints and tendons and muscles and the soles of his feet which
ordinarily convey to him the position and state of motion of his legs
send no messages which his central nervous system can pick up and
transmit, and for information concerning his posture he is obliged
to trust his eyes and the balancing organs of his inner ear. In the
jargon of the physiologist, he has lost an important part of his
proprioceptive or kinaesthetic sense. [3]
In other words, the patient's sensory hierarchy, which provides the
feedback to the controlling centre, has been impaired. All sensory-motor
skills, from riding a bicycle to touch-typing and piano-playing,
operate by means of feedback loops, provided by the complex networks
which connect the two branches of the hierarchy.
But let us beware of using the principle of feedback control as a
magic formula which explains everything -- as computer theoreticians
occasionally tend to do. The concept of feedback, without the concept of
hierarchic order, is like the grin without the cat. We have seen that the
performance of a skill follows a pre-set pattern, according to certain
rules of the game. These are fixed, but sufficiently elastic to permit
constant adjustments to variable environmental conditions. Feedback can
only operate within the limits of those fixed rules -- the 'canon' of
the skill. The part which feedback plays is to report back on every step
in the progress of the operation, whether it is overshooting or falling
short of the mark, how to keep it on an even keel, when to intensify the
pace and when to stop. But it cannot alter the intrinsic pattern of the
skill. The tit building its nest has a conception of its shape somehow
represented in its nervous system -- otherwise the nests of all tits
would not be alike; the constant feedback it receives through eye and
touch merely tells the bird when 'weaving' should stop and be followed
by 'trampling', and when that should be followed by 'lining'. One of
the vital differences between the S-R concept and the present theory
is that according to the former, the environment determines behaviour,
whereas according to the latter, feedback from the environment merely
guides or corrects or stabilises
a pre-existing pattern of behaviour.
The primacy and autonomy of such patterns of instinct-behaviour have been
strongly emphasised in recent years by ethologists like Lorenz, Tinbergen,
Thorpe, etc., and by biologists like v. Bertalanffy and Paul Weiss.*
Our acquired skills display the same autonomy. As I am writing these
lines, I am getting a constant feedback of the pressure of pen against
paper through my fingers, and of the progress of the script through my
eyes. But these do not alter the pattern of my handwriting, they merely
keep it on an even keel; for, even with closed eyes, my writing will
merely get shaky, but its pattern will remain unmistakably the same.
* e.g., P. Weiss: 'The structure of the input does not produce
the structure of the output, but merely modifies intrinsic nervous
activities which have a structural organisation of their own.' [4]
Or, v. Bertalanffy: 'The stimulus (that is, an alteration of
external conditions) does not cause a process in an internally
inactive system, but rather modifies the process in an internally
active system.' [5]
Loops within Loops
So far I have talked about sensory feedback guiding motor activities. But
the cross-traffic in the network works both ways, and perception is
guided by the intervention of motor activities. Seeing is inextricably
mixed up with motion -- from the large motions of head and eyeballs,
down to the involuntary minute eye motions -- drift, flicker, tremor --
without which we cannot see at all. Similarly with hearing: if you try
to recall a tune, to reconstruct its auditory image, what do you do? You
hum it. The perceptual and motor hierarchies are so intimately correlated
on every level that to draw a sharp distinction between 'stimulus' and
'response' becomes arbitrary and meaningless. Both have been swallowed
up by feedback loops, along which impulses run in circles like kittens
chasing their tails.*
* 'Because stimulus and response are correlative and contemporaneous,
the stimulus processes must be thought of not as preceding
the response, but rather as guiding it to a successful
[conclusion]. That is to say, stimulus and response must be
considered as aspects of a feedback loop' (Miller et al. [6]).
Let me illustrate this by a celebrated experiment. A cat's auditory nerve
was wired to an electric apparatus so that nerve impulses transmitted
from the ear to the brain could be heard in a loudspeaker. A metronome
was kept going in the room, and its clicks, as transmitted by the cat's
auditory nerve, and amplified by the apparatus, were clearly audible. But
when a mouse in a jar was brought into the room, the cat not only lost
interest in the metronome, as one would expect, but the impulses in its
auditory nerve became feebler or stopped altogether. This is a dramatic
example of how the admission of stimuli at a peripheral receptor-organ --
the outermost Kremlin gate -- can be controlled from the centre.
The lesson taught by this and similar experiments can be best summed
up by way of an anecdote. In the good old days before the turn of the
century, Vienna had a mayor, called Lueger, who professed to a mild form
of anti-semitism. But he also cultivated a number of Jewish friends. When
taken to task over this by one of his cronies, Lueger gave the classic
answer: 'I am the Burgomaster, and
I
decide who is a Jew and who is
not.' Mutatis mutandum, the cat watching the mouse and turning a deaf
ear to the metronome may just as well have said: It's
I
who decide
what is a stimulus and what is not.'
A Holarchy of Holons
Let us carry this inquiry into the meaning of current terminology a step
further, and ask just what that convenient word 'environment' is meant
to signify.
When I am driving my car along a country road, the environment in contact
with my right foot is the accelerator-pedal, and the environment in
contact with my left foot is the clutch-pedal. The elastic resistance
to pressure of the accelerator provides a tactile feedback which helps
to keep the speed of the car steady, while the clutch controls another
invisible environment, the gearbox. The feel of the wheel under my
hands acts like a servo-mechanism to keep a straight course. But my
eyes encompass a much larger environment than my feet and my hands;
it determines the overall strategy of driving. Thus the hierarchically
organised creature that I am is in fact functioning in a hierarchy of
environments, guided by a hierarchy of feedbacks.
One advantage of this interpretation is that the hierarchy of environments
can be extended indefinitely. When a chess player stares at the board
in front of him, the environment in which his thoughts operate is
determined by the distribution of chess-men on the board. Assume that
the situation allows twenty possible moves permitted by the rules of the
game, and that five of these look promising. He will consider each in
turn. A good player may be able to think at least three moves ahead --
by which time the game would have branched out into a great variety of
possible situations, each of which the player must try to visualise in
order to decide on his initial move. In other words, he is guided by
feedbacks from an imagined board, in an imagined environment. Most of
our thinking, planning and creating operates in imaginary environments.
We have seen, however, that all our perceptions are coloured by
imagination. Thus the difference between 'real' and 'imaginary'
environments becomes a matter of degrees -- or rather of levels, ranging
from the unconscious phenomena of projecting figures into the Rohrschach
blot, to the chess master's uncanny powers of inventing the future. Which
is just another way of repeating that the hierarchy is open at the top.