Janus (44 page)

^[9]
proposed
the word 'holon' for these Janus-faced sub-assemblies.

 

 

The concept of the holon is meant to supply the missing link between
atomism and holism, and to supplant the dualistic way of thinking in
terms of 'parts' and 'wholes', which is so deeply engrained in our mental
habits, by a multi-level, stratified approach. A hierarchically-organized
whole cannot be 'reduced' to its elementary parts; but it can be 'dissected'
into its constituent branches of holons, represented by the nodes of the
tree-diagram, while the lines connecting the holons stand for channels
of communication, control or transportation, as the case may be.

 

 

FIXED RULES AND FLEXIBLE STRATEGIES

 

The term holon may be applied to any stable sub-whole in an organismic,
cognitive, or social hierarchy which displays rule-governed behaviour
and/or structural Gestalt constancy.
Thus biological holons are
self-regulating open systems'
^[10]
governed by a set of fixed
rules which account for the holon's coherence, stability and its specific
pattern of structure and function. This set of rules we may call
the
canon of the holon
.* The canon determines the fixed, invariant aspect
of the open system in its steady state (
Fliessgleichgewicht
--
dynamic equilibrium); it defines its pattern and structure. In other types
of hierarchies, the canon represents the codes of conduct of social holons
(family, tribe, nation, etc.); it incorporates the 'rules of the game'
of instinctive rituals or acquired skills (behavioural holons); the rules
of enunciation, grammar and syntax in the language hierarchy; Piaget's
'schemes' in cognitive hierarchies, and so on. The canon represents
the constraints imposed on any rule-governed process or behaviour. But
these constraints do not exhaust the system's degrees of freedom; they
leave room for more or less
flexible strategies
, guided by the
contingencies in the holon's local environment.

 

* Cf. the 'organizing relations' or 'laws of organization' of earlier
writers on hierarchic organization (e.g., Woodger (1929), Needham
(1941), and the 'system-conditions' in general system theory.

 

It is essential at this point to make a sharp, categorical distinction
between the fixed, invariant canon of the system and its flexible
(plastic, variable) strategies. A few examples will illustrate the
validity of this distinction. In ontogeny, the apex of the hierarchy
is the zygote, and the holons at successive levels represent successive
stages in the development of tissues. Each step in differentiation and
specialization imposes further constraints on the genetic potential of the
tissue, but at each step it retains sufficient developmental flexibility
to follow this or that evolutionary pathway, within the range of its
competence. guided by the contingencies of the cell's environment --
Waddington's
^[11]
'strategy of the genes'. Turning from
embryonic development to the
instinctive activities
of the mature
animal, we find that spiders spin webs, birds build nests according to
invariant species-specific canons, but again using flexible strategies,
guided by the lie of the land: the spider may suspend its web from
three, four or more points of attachment, but the result will always be
a regular polygon. In acquired skills like chess, the rules of the game
define the permissible moves, but the strategic choice of the actual
move depends on the environment -- the distribution of the chessmen
on the board. In symbolic operations, the holons are rule-governed
cognitive structures variously called 'frames of reference', 'universes
of discourse', 'algorithms', etc., each with its specific 'grammar or
canon; and the strategies increase in complexity on higher levels of
each hierarchy. It seems that life in all its manifestations, from
morphogenesis to symbolic thought, is governed by rules of the game
which lend it order and stability but also allow for flexibility; and
that these rules, whether innate or acquired, are represented in coded
form on various levels of the hierarchy, from the genetic code to the
structures in the nervous system responsible for symbolic thought.

 

 

TRIGGERS AND SCANNERS

 

Let me discuss briefly some specific characteristics of what one might
loosely call
output hierarchies
, regardless whether the 'output' is
a baby, or a sentence spoken in English. However much their products
differ, all output hierarchies seem to have a classic mode of operation,
based on the trigger-releaser principle, where an implicit coded signal
which may be relatively simple, releases complex, pre-set mechanisms.

 

 

Let me again run through a few examples. In
phylogeny
,
Waddington
^[12]
and others have convincingly shown that
a single favourable gene-mutation can act as a trigger to release a
kind of chain-reaction which affects a whole organ in a harmonious
way. In
ontogeny
, the prick of a fine platinum needle on the
unfertilized egg of a frog or sheep triggers off parthenogenesis. The
genes act as chemical triggers, catalysing reactions. The implicit
four-letter alphabet of the DNA chain is spelled out into the explicit,
twenty-letter alphabet of amino-acids; the inducers or evocators,
including Spemann's 'general organizer', again turn out to be relatively
simple chemicals which need not even be species-specific to activate
the genetic potentials of the tissue. In
instinct behaviour
,
we have releasers of a very simple kind -- the red belly of the
stickleback, the spot under the herring-gull's beak, which trigger
off the appropriate behaviour.
^[13]
In the performance of
acquired skills
you have the same process of step-wise filling in
the details of implicit commands issued from the apex of the hierarchy,
such as 'strike a match and light this cigarette' or 'sign your name',
or 'use your phrase-generating machine' to transform an unverbalized
image into innervations of the vocal chords.

 

 

The point to emphasize is that this spelling-out process, from intent to
execution, cannot be described in terms of a linear chain of S-R units,
only as a series of discrete steps from one open sesame, activated
by a combination lock, to the next. The activated holon, whether
it is a government department or a living kidney, has its own canon
which determines the pattern of its activity. Thus the signal from
higher quarters does not have to specify what the holon is expected
to do; the signal merely has to trigger the holon into action by a
coded message. Once thrown into action, the holon will spell out the
implicit command in explicit form by activating its sub-units in the
appropriate strategic order, guided by feedbacks and feed-forwards
from its environment. Generally speaking,
the holon is a system of
relations which is represented on the next higher level as a unit,
that is, a relatum
.

 

 

If we turn now to the
input hierarchies
of perception, the operations
proceed, of course, in the reverse direction, from the peripheral twigs
of the tree towards its apex; and instead of trigger-releasers we have
the opposite type of mechanisms: a series of filters, scanners or classifiers
through which the input traffic must pass in its ascent from periphery to
cortex. First you have lateral inhibition, habituation and presumably some
efferent control of receptors. On the higher levels are the mechanisms
responsible for the visual and acoustic constancy phenomena, the scanning
and filtering devices which account for the recognition of patterns in space
and time, and enable us to abstract universals and discard particulars.
The colloquial complaint: 'I have a memory like a sieve' may be derived
from an intuitive grasp of these filtering devices that operate first
all along the input channels, then along the storage channels.

 

 

How do we pick out a single instrument in a symphony? The whole medley of
sounds arriving at the ear-drum is scrambled into a linear pressure-wave
with a single variable. To reconstruct the timbre of an instrument, to
identify harmonies and melodies, to appreciate phrasing, style and mood,
we have to abstract patterns in time as we abstract visual patterns in
space. But how does the nervous system do it? I will play you the opening
bars of the
Archduke Trio
; watch your reactions, because no text-book
on psychology that I know of will give you the faintest clue [opening
bars of Beethoven's
Archduke Trio
played]. If one looks at the record
with a magnifying glass, one is tempted to ask the naive question why the
nervous system does not produce engrams by this simple method of coding,
instead of being so damned complicated. The answer is, of course, that a
linear engram of this kind would be completely useless for the purpose
of analysing, matching and recognizing input patterns. The chain is a
hopeless model; we cannot do without the tree.

«serial vs random access»

 

In motor hierarchies, an implicit intention or generalized command is
particularized, spelled out, step by step, in its descent to the periphery.
In perceptual hierarchies, we have the opposite process. The peripheral
input is more and more de-particularized, stripped of irrelevancies
during its ascent to the centre.
The output hierarchy concretizes, the
input hierarchy abstracts.
The former operates by means of triggering
devices, the latter by means of filtering or scanning devices. When I
intend to write the letter R, a trigger activates a functional holon,
an automatic pattern of muscle contractions, which produces the letter R
in my own particular hand-writing. When I read, a scanning device in my
visual cortex identifies the letter R regardless of the particular hand
that wrote it. Triggers release complex outputs by means of a simple
coded signal. Scanners function the opposite way: they convert complex
inputs into simple coded signals.

 

 

'ABSTRACT' AND 'SPOTLIGHT'

 

Let me briefly turn to the phenomena of
memory
and ask whether the
hierarchic approach is capable of shedding some additional light on
them. You watch a television play. The exact words of each actor are
forgotten by the time he speaks his next line, and only their meaning
remains; the next morning you can only remember the sequence of scenes
which constituted the story; after a month, all you remember is that
it was about a gangster on the run or about two men and a woman on a
desert island. The same happens generally with the content of novels
one has read, and episodes one has lived. The original experience
has been stripped of detail, reduced to a schematic outline. Now this
skeletonization of the input before it is put into storage, and the
gradual decay of the stored material, would mean a terrible impoverishment
of memory, if this were the whole story -- memory would be a collection
of dusty abstracts, the dehydrated sediments in the wine-glass, with all
flavour gone. But there are compensating mechanisms. I can recognize a
melody, regardless of the instrument on which it is played, and I can
recognize the timbre of an instrument, regardless of the melody played on
it. There are several interlocking hierarchies at work, each with its own
criteria of relevance. One abstracts melody and treats everything else as
noise, the other abstracts timbre and treats melody as noise. Thus not
all the information discarded as irrelevant by one filtering system is
irretrievably lost, because it may have been stored by another filtering
hierarchy with different canons of relevance. Recall would then be made
possible by the cooperation of several interlocking hierarchies, which may
pertain to different sense modalities -- sight and smell, for instance;
or, what is less obvious, there may also be several distinct hierarchies
with different criteria or relevance operating within the same sense
modality. Recall could then be compared to the process of multi-coloured
printing by the superimposition of several colour-blocks. This, of course,
is speculative, but some modest evidence for the hypothesis can be found
in a series of experiments by J. J. Jenkins and myself; *
^[14]
and more tests on these lines can be designed without much difficulty.

 

* See Appendix II.

 

I am aware that the hypothesis is in apparent contradiction to Penfield's
^[15]
experiments eliciting what looks like total recall of past experiences
by electrical stimulation of points on the patient's temporal lobe. But the
contradiction may be resolved if we include in the criteria of relevance
also criteria of
emotional
relevance which decide whether an input is
worth storing. A detail might be emotionally relevant (on a conscious or
unconscious level), and retained with almost photographic or cinematographic
clarity. One might call this the
spotlight
type of memory which is stamped
in, as distinct from
abstractive
memory which schematizes. Spotlight
memories may be related to eidetic images; and they might even, unlike
abstractive memories, originate in the limbic system.
^[16]

 

 

ARBORIZATION AND RETICULATION

 

I have used the term 'interlocking' or 'interlacing' hierarchies. Of course
hierarchies do not operate in a vacuum. This truism regarding the
interdependence of processes in an organism is probably the main cause
of confusion which obscured from view its hierarchic structure. It is as
if the sight of the foliage of the entwined branches in a forest made
us forget that the branches originate in separate trees. The trees are
vertical structures. The meeting points of branches from neighbouring
trees form horizontal networks at several levels. Without the trees
there could be no entwining, and no network. Without the networks,
each tree would be isolated, and there would be no integration of
functions. Arborization and reticulation seem to be complementary
principles in the architecture of organisms. In symbolic universes
of discourse arborization is reflected in the 'vertical' denotation
(definition) of concepts, reticulation in their 'horizontal' connotations
in associative networks. This calls to mind Hyden's proposal that the same
neuron, or population of neurons, may be a member of several functional
'clubs'.