continued
in 2nd part
[p.57:]
In talking to younger psychologists, one finds that many of them seem to believe
that perception is something at the surface of the mind, a kind of borderline problem,
and that preoccupation with it is obsolete. They look with disdain at every psychological
problem that does not at least deal with personality, motivation, or social intercourse.
But when discussing problems in which simple facts of stimulus and reaction play
a role, as for example in behavior therapy, they prove that they would have done
well to occupy themselves a little more with the fundamentals of perception. It
is hard to get them clear on the differences between a stimulus in the physiological
sense, such as impingement on receptor cells, and a valence or Aufforderungscharakter
in the sense of Kurt LEWIN, or an IRM in the sense of ethology. Obviously they have
never been confronted with facts that can only be understood by carefully distinguishing
between an impact on a sense organ and a characteristic of a percept that has come
into existence through such impacts, and which therefore cannot again act on a sense
organ of the same organism but only on the perceiving subject. Subjects correspond
somehow to organisms, but are percepts themselves existing within the same phenomenal
world as the objects to whose valences or IRMs they react. Psychologists of the
younger generation tend to forget that, taken strictly, all social interaction is
primarily interaction between percepts, interaction which only by cybernetic mechanisms
is transferred to the participating organisms and copied by them, so that the interaction
of the organisms is but a mediating correlate of what happens in the phenomenal
worlds of the interacting subjects. And if this is the case, the theory of perception
plays a fundamental role for every other field of psychology (cf. METZGER, 1965,
1968, 1969; GRAEFE, 1961).
[p. 58:]
Phenomenal worlds are not exact reflections of the physical world. What is lacking
in them, if compared with it, can be seen in any physics textbook. But on the other
hand they have quite a number of essential characteristics that cannot be found
in the physical world: the secondary and tertiary qualities of percepts and situations
and the valences and tensions existing between them have no counterpart in the corresponding
physical facts. But still they represent the physical facts so reliably, and their
deviations from them correspond so highly, that different subjects in spite of their
different standpoints can consider their respective phenomenal worlds as identical,
that is, as, for all practical purposes, one and the same objective reality.
How do these phenomenal worlds come about? The question has at least partially been
answered by psychophysics, if this term is taken in a sonewhat loose sense. The
decisive point is that there is no direct communication between physical objects
and percepts corresponding to them, but that between them there is a more or less
long and complicated chain of causation whose critical link is the stimulation of
receptors, that is, the initial penetration of the organism. This point is decisive.
For the only basis of a phenomenal world is the totality of stimulations of millions
and millions of receptor cells in their ever-changing distribution, as called forth
by the changes in the objects themselves and by changes in the relations between
objects and organisms as caused by the subject itself, whether impulsively or intentionally.
Percepts are never structurally identical with the varying configurations on the
receptor level. Percepts are units or wholes coherent in themselves and segregated
from each other; stimuli are not. Percepts are tri-dimensional and move in a tri-dimensional
space; underlying stimuli are distributed over two-dimensional surfaces of the body,
such as retinae or the skin of the fingertips. Percepts have (approximately) constant
attributes such as size, shape, surface color, and so on, just as their physical
counterparts do, while the underlying stimulus configurations vary continuously.
For these reasons percepts are in decisive characteristics more like objects than
like the stimuli intercalated between objects and percepts. Thus some thinkers (such
as Max SCHELER) have been inclined to assume a direct, extrasensory connection between
the two ends of the chain. Another attempt at accounting for the astonishing correspondence
between the two ends of the causal chain between object and percept that must be
[p. 59:]
noted here is J.J. GIBSON's; if I do not misunderstand him he holds that
this chain is circular in the sense that it finally returns to ist starting point
(GIBSON, 1966). The formulations of these authors raise many new and unsolved problems.
Therefore the conventional conception is preferable according to which there is
neither direct connection nor identity between object and percept. This leaves the
basic theoretical question of how and by what factors varying stimulus configurations
are transformed into stable percepts.
The oldest source in which it is held that the ego creates its own world by an
act of will is J. G. FICHTE's Introduction to Philosophy (Einleitungsvorlesungen
in die Wissenschaftslehre, 1797), in which he tries to interpret KANTian epistemology.
But his arguments are so highly speculative and so far from empirical evidence that
in this connection he shall only be mentioned.
Twenty years later, in 1818, Arthur SCHOPENHAUER dealt with a concrete problem of
perception. His problem is how it happens that objects are seen where they are,
instead of at the place of the physiological processes in the retina or in the cortex.
According to his hypothesis, the subject follows the light rays back to the point
on the surface of an object from which they diverge to the foveae of the two eyes,
and, recognizing the angle between them, is able to reconstruct its place. With
this, he in a way anticipates the theory of judgement or inference brought forward
by HELMHOLTZ in about 1860.
The starting point of HELMHOLTZ's theory is that invariably the nervous stimulations
(we should say excitations) are directly perceived, but never the objects themselves.
(Or in a more general and less hypothetical formulation: the immediate basis
of object perception is invariably the sum of stimulations of receptor cells but
never the objects themselves.) HELMHOLTZ continues his argument as follows: "But
there are mental activities that enable us to form an idea as to the possible causes
of the observed actions on the senses. In their result, these activities are equivalent
to a conclusion or inference from analogy"; this is the well-known theory of
unconscious inference. (From this follows his explanation of visual illusions as
"erroneous interpretations" [Urteilstäuschungen].) HELMHOLTZ
does not deny that there are certain differences between the hypothesized analogical
inference made by the subject and his observable free acts of conscious
[p. 60]
inference: the former are instantaneous; they are unconscious, and - as Wolfgang
KÖHLER (1913) adds - concerned with unconscious material; they are irresistible,
that is, cannot be corrected by better knowledge. There is one more fundamental
difference that was not yet known to HELMHOLTZ and KÖHLER: conscious inferential
thinking becomes the more difficult the higher the complexity of the problem situation
grows. However, with the phenomena that HELMHOLTZ intended to explain by unconscious
inference, this relation is exactly reversed: the more complex the situation, the
more irresistible and unambiguous the effect (METZGER, 1934).
Actually there are many more problems left open. Everybody knows what "an idea
to a possible cause" is, and that an idea such as a pure thought or a mental
image is quite different from a true percept, that is from a thing of our environment
that can be seen and manipulated. And the question arises how this special kind
of idea is related to the palpable things in our surroundings through processes
originating in the retina and skin receptors. Another problem is the unavoidable
inference that the subject must sit in the middle of the organism and from there
observe all the stimulations around him, forming ideas as to their possible causes,
ideas which by a rather miraculous additional act are "projected" or "externalized"
beyond the surface of the organism into its nearer or farther surroundings.
KÖHLER (1913) points to the fact that no unconscious inferences are assumed
by HELMHOLTZ if a plausible objective explanation for a phenomenon exists, as in
the case of color mixture. Actually, HELMHOLTZ´s theory applies to all those
phenomena which cannot be understood without the assumption of lateral interaction
of simultaneous nervous processes (Querfunktionen, as WERTHEIMER called it
in 1912). Lateral interaction was not yet believed to be possible in the nervous
system at HELMHOLTZ`s time. Unconscious reasoning as well as unconscious sensations
were constructs that could be dispensed with as soon as this possibility had been
acknowledged.
Nevertheless, HELMHOLTZ´s theory is still alive. More than forty years after
KÖHLER`s criticism it has been revived by TAUSCH (1954), KRISTOF (1961), and
GREGORY (1962), but was refuted again by ZANFORLIN (1967), FISHER (1968), and METZGER
et.al. (1970). One more instance of a relapse into HELMHOLTZian speculations can
be found in an article on decision
[p. 61:]
theory by SWETS et al. (1964). We owe to these authors not only the wellknown
concept of sensitivity, but also the concept of choice of criterion in threshold
observations, which means a valuable step forward in this field. But their decision
theory makes sense only in the peculiar situation of threshold exposure, when the
subject, presented with the task of detecting something hardly perceptible, is forced
to make decisions observable by himself and by the experimenter. But the authors
go further and try to apply their new-found principle to perception in general,
with paradoxical consequences. Their generalization would imply that, for example,
(1) while looking at a human face, a crowd in the street, a landscape, or a bunch
of flowers, thousands of decisions would be necessary at one and the same moment,
and that (2) all these decisions would never be noticed - in constrast to the observable
deciding activity in threshold experiments.
But the whole waste of unconscious activities need not be assumed, because if the
perceiver contents himself with clearly supraliminal differences, as is the case
in all naive everyday vision in which no searching attidude is maintained, there
is nothing to decide.
The most recent publication in which HELMHOLTZ´s theory expressly adopted
is "Die Psychophysiologischen Grundlagen des Wahrnehmens" ("The psysiological
foundations of perceiving") by Egon KÜPPERS, a German psychiatrist (1971).
But the abundance of fictitious mental activities introduced by him goes far beyond
HELMHOLTZ.
There are still other types of mental-act-theories of perception. In his Sinnespsychologische
Untersuchungen (Sensory Psychological Investigations) of 1917 (which, by the
way, are full of interesting and reliable observations), Julius PIKLER offers a
theory of binocular depth perception according to which the subject is able to observe
separately the two retinal images of the right and left eyes, to interpret them
as geometrical projections of solid bodies, to compare them and from their deviations
to draw conclusions as to the distance and shape of the object represented by them.
The "Komplextheorie", first brought forward by MÜLLER (1903, 1923)
and later with slight alterations by PETERMANN (1929, 1931), deserves special mention,
along with the "Produktionstheorie" of MEINONG and BENUSSI (1904). These
are theories of unit formation and unit segregation in perception that agree in
the assumption of a special mental activity on he part of the subject. He organizes
the perceptive field out of the crowd of unconnected elementary sensations by "producing"
real - as opposed
[p. 62:]
to merely imagined - relations between them or by directing collective or
unifying attention to them.
These theories have the advantage of being based on activities of the subject that
under certain conditions can actually be observed. Everybody knows what attention
is, and can discriminate between an attentive and an inattentive state of mind.
Beyond this, everybody knows the difference between seeing, for example, four points
either as the corners of a square or as the ends of a cross, and can experience
how by a change of attitude one of these apprehensions of the configuration can
be changed into the other. (By the way, these two are not the only alternatives!)
In the theories of production or collectice attention this observable unifying mental
activity is generalized to all cases of unit formation, and where it - as in the
vast majority of cases - cannot be observed, it is thought to work unconsciously.
BÜHLER (1913) and KÖHLER (1926) have pointed to the numerous facts that
contradict such assumptions. The range of deliberate unification proved to be surprisingly
narrow; unit formation in innumerable cases does not follow intentional, and to
that extent observable, unifying or segregating efforts, and so many objective "cues"
controlling attention behavior must be introduced by these authors right from the
outset (MÜLLER, 1903), that finally the concept of attention is reduced to
an x that occasions the subject to build very definite units, an x
that can be omitted without any loss if the "cues" of these theories are
considered as factors acting immediately upon the perceptive field.
To sum up, none of the know theories of "creating" one´s own world
by mental acts has proved to be adequate to facts.
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