Free Janus by Arthur Koestler Page B

compensating factors which, at least in part, make up for
the loss.
     
     
In the first place, the abstractive process can acquire a higher degree
of sophistication by learning from experience. To the novice, all red wines
taste alike, and all Japanese males look the same. But he can be taught
to superimpose more delicate perceptual filters on the coarser ones,
as Constable trained himself to discriminate between diverse types of clouds
and to classify them into sub-categories. Thus we learn to abstract finer
and finer nuances -- to make the trees of the hierarchies of perception
grow new shoots, as it were.
     
     
Moreover, it is important to realize that abstractive memory is not based
on a single hierarchy but on several interlocking hierarchies pertaining
to different sensory realms such as vision, hearing, smell. What is less
obvious is that there may exist several distinct hierarchies with different
criteria of relevance operating within the same sense modality. I can
recognize a melody regardless of the instrument on which it was played;
but I can also recognize the sound of an instrument regardless of the
melody played on it. We must therefore assume that melodic pattern and
instrument sound (timbre) are abstracted and stored independently by
separate filtering hierarchies within the same sensory modality but with
different criteria of relevance . One abstracts melody and disregards
timbre, the other abstracts the timbre of an instrument and disregards
melody as irrelevant. Thus not all the detail discarded as irrelevant
by one filtering system is irretrievably lost, because it may have been
retained and stored by another filtering hierarchy with different criteria
of relevance.
     
     
The recall of an experience would then be made possible by the cooperation
of several interlocking hierarchies, which may include different sense
modalities, for instance, sight and sound or odour, or different branches
within the same modality. You may remember the words of the aria 'Your Tiny
Hand is Frozen', but have lost the tune. Or you may remember the tune
after having forgotten the words. And you may recognize the unique timbre
of Caruso's voice on a gramophone record, regardless of the words and
the tune he is singing. But if two, or all three of these features have
been abstracted and stored, the recall of the original experience will
have more dimensions and be the more complete.
     
     
The process could in some respects be compared to multi-colour printing
by the superimposition of several colour-blocks. The painting to be
reproduced -- the original experience -- is photographed through
different colour-filters on blue, red and yellow plates, each of
which retains only those features that are 'relevant' to it: i.e.,
those which appear in its own colour, and ignores all other features;
then they are recombined into a more or less faithful reconstruction of
the original input. Each hierarchy would then have a different 'colour'
attached to it, the colour symbolizing its criteria of relevance .
Which memory-forming hierarchies will be active at any given time depends,
of course, on the subject's general interests and momentary state of mind.
     
     
Although this hypothesis represents a radical departure from both the
behaviourist and the Gestalt schools' conceptions of memory, some modest
evidence for it can be found in a series of experiments carried out in
cooperation with Professor J. J. Jenkins in the psychological laboratory
of Stanford University;* and more tests on these lines can be designed
without much difficulty.
     
* See Appendix II. This is a rather technical paper of possible
     interest to experimental psychologists, which the general reader
     can safely ignore. The gist of the experiment was to show to each
     subject for a fraction of a second only (by means of an apparatus
     called a tachistoscope) a number of seven or eight digits, and
     then let him try to repeat the sequence. The results of several