link. In other words, it seems that an
innate tendency to integrate simultaneous and successively induced perceptions leads us to an awareness of a
causal relationship. The achievement
of insight into cause and effect brings
a feeling of satisfaction and relieves
psychic tension. A simple example may
illustrate this psychophysiological assertion. From my desk I see on the
horizon a dark bank of clouds coming
nearer and nearer. Suddenly lightning
from the cloud strikes the earth. A
little later I hear the thunder.Momentarily ignoring earlier experiences of
this nature, I am confronted with a
visual, followed by an auditory, experience. The two phenomena manifest themselves independently of one
another. Continuing to watch, out of
curiosity, I see after some time another flash of lightning and hear again,
later, a clap of thunder. Repetitions of
these essentially identical sensory experiences lead inescapably to the interpretation that the optical and the
subsequent acoustical phenomena are
somehow related.
With increasing frequency of repetition analogous successions are established as associative links, so that the
conjecture of a causal relationship ultimately assumes the character of a certainty. Strictly speaking, no certainty
exists but, at best, a high degree of
probability. In everyday life one is, to
be sure, surprisingly ready to assume
a causal relationship. Obviously such
a “short circuit” ordinarily suffices as
a basis for adaptive behavior. In the
case of a scientific investigation, one
requires a higher number of identical
successions before being. ready to accept the intuitively conceived causal relationship as an established reality,
Even then, in the area of biology at
Jeast, the causal relationship remains
basically conjectural as long as the
number of repetitions is not infinite.
Nevertheless, we have to admit that,
even in the pursuit of scientific interest,
the number of repetitions required be-
fore the impression of pure coincidence
is eliminated is relatively soon reached.
After all, the willingness to think post
hoc, propter hoc depends to a con-
siderable degree on the personality of
the observer. Irrespective of the number of repetitions, the persuasive power
of the repetitions depends on conditional factors. There are men, for example, with a strong inclination to associate a comparatively short series of
successive similar data with one an1280
other in the sense of a causal relation-
ship. On the other hand, one knows
laymen and researchers of outspoken
skepticism who will not integrate successive similar data into an inferred
causal chain even when the probability
of an accidental succession is low. In
the tendency to integrate or not to
integrate, the individual’s temperament,
his previous experiences, his physical
health, and his biological constitution
play a not unimportant role. When the
probable causal relationship offers a reward, he may be more likely to accept it. Further, mental age is a factor
—as is seen, for example, when the
child experiences a fairy tale as reality.
The young,still inexperienced observer
instinctively attempts to find a causal
relationship, while the mature person
is critical and does not exclude accidental succession so quickly. In the
end, none of these arguments alters
the fact that reality provides no objective criteria for arriving at a construct of causal relationships.
The Physiological Basis
of Consciousness
The waking human being or higher
animal has a large number of sense
organs for making contact with the
internal and external environment. The
sensory cells function as receptors of
organ-specific stimuli. Light flashes, for
example, stimulate the rods and cones
of the retina of the eye. Thereby the
order of optic phenomena generated
by the visual system is transformed into
patterns of excitation of the visual path-
ways whose morphological organization is relatively well known (9)—for
example, the projection of circumscribed retinal areas to corresponding
elements of the visual areas in the
occipital lobes of the brain. Far less
advanced is exploration of the func-
tional laws of the living bra. Actually,
research in this sector of physiology
is only now in process of develop-
ment, The school of Jung (70) and the
team of Hubel and Wiesel (77) have
made significant contributions, particularly with respect to visual perception. Basic information is derived from
observations concerning electrical stimulation of the visual cortex in man
(4). Patients subjected to such stimula-
tion in an effort to localize pathological foci in that area reported visual
phenomena arising with the onset of
stimulation. The sense of hearing was
similarly involved when the stimulating
electrode was applied to a certain region of the temporal lobe. Further, it
has been experimentally established
that the visual and auditory sensations
experienced
are
associated
with
one
another in the sense of a “causal” connection on the basis of temporal coincidence or spatial contiguity. In such
cases consistent relationships between
brain stimulation and subjective sensations (4) are as evident as those exist-
ing between natural stimuli and a determined flow of consciousness.
Findings such as the foregoing raise
the question, How may the “causal”
relationship between excitatory patterns
of the nervous system and the development of conscious perceptions come
about? Before we pose this problem,
we must acknowledge that it is not
now possible, and may not be possible in the future, to obtain such in-
formation. The subjective experience
may be a direct expression of the condition of excitation of those centers
which receive and integrate the sensory signals. In this case it would be
only another aspect of the same process which one can objectify in the
form of evoked: potentials. An alternative explanation would be that of transmission of the integrated excitation
pattern to a specific system whose principal activity is one of implementing
release of the contents of consciousness.
However, no criteria which would al-
low us to define such a process of
transmission are, as yet, known. For
the entire process which leads from
the sensory stimulation pattern to the
content of consciousness results exclu-
sively in the mediating of relevant information. The process of transmission
itself lies in an area into which we
have no insight. Obviously reference
to a reflex mechanism leads no further,
so that physiology must give up the
attempt to submit a comprehensive ex-
planation. This is not to deny that
there is a correlation between patterns
of neural excitation and the release of
corresponding contents of consciousness.
.
This situation is not unlike that
existing with respect to verbal communication. The listener is unaware of
the pressure changes acting upon his
eardrum, and he does not perceive
their transmission upon the sensory
surface within the organ of Corti. Nor
is he aware of the nervous impulses
which are sent from the organ of Corti
to the auditory centers of the brain. .
SCIENCE, VOC. 158