Just as the sense of sight is the most dignified of all our senses, it
is also the most important in the criminal court, for most witnesses
testify as to what they have seen. If we compare sight with the hearing,
which is next in the order of importance, we discover the well-known
fact that what is seen is much more certain and trustworthy than what is
heard. “It is better to see once than to hear ten times,” says the
universally-valid old maxim. No exposition, no description, no
complication which the data of other senses offer, can present half as
much as even a fleeting glance. Hence too, no sense can offer us such
surprises as the sense of sight. If I imagine the thunder of Niagara,
the voice of Lucca, the explosion of a thousand cartridges, etc., or
anything else that I have not heard, my imagination is certainly
incorrect, but it will differ from reality only in degree. It is quite
different with visual imagination. We need not adduce examples of
magnificence like the appearance of the pyramids, a tropical light; of a
famous work of art, a storm at sea, etc. The most insignificant thing
ever seen but variously pictured in imagination will be greeted at first
sight with the words: “But I imagined it quite different!” Hence the
tremendous importance of every local and material characteristic which
the criminal court deals with. Every one of us knows how differently he
has, as a rule, imagined the place of the crime to be; how difficult it
is to arrive at an understanding with the witness concerning some
unseen, local characteristic, and how many mistakes false images of the
unseen have caused. Whenever I ciceroned anybody through the Graz
Criminal Museum, I was continually assailed with “Does this or that look
so? But I thought it looked quite different!” And the things which evoke
these exclamations are such as the astonished visitors have spoken and
written about hundreds of times and often passed judgments upon. The
same situation occurs when witnesses narrate some observation. When the
question involves the sense of hearing some misunderstanding may be
popularly assumed. But the people know little of optical illusions and
false visual perceptions, though they are aware that incorrect auditions
are frequent matters of fact. Moreover, to the heard object a large
number of more or less certain precautionary judgments are attached. If
anybody, e.g., has _heard_ a shot, stealthy footsteps, crackling flames,
we take his experience always to be _approximate_. We do not do so when
he assures us he has _seen_ these things or their causes. Then we take
them--barring certain mistakes in observation,--to be indubitable
perceptions in which misunderstanding is impossible.
In this, again, is the basis for the distrust with which we meet
testimony concerning hearsay. For we feel uncertain in the mere absence
of the person whose conversation is reported, since his value can not be
determined. But a part of the mistrust lies in the fact that it is not
vision but the perennially half-doubted hearing that is in issue. Lies
are assigned mainly to words; but there are lies which are visual
(deceptions, maskings, illusions, etc.). Visual lies are, however, a
diminishing minority in comparison with the lies that are heard.
The certainty of the correctness of vision lies in its being tested with
the sense of touch,--i.e. in the adaptation of our bodily sense to
otherwise existing things. As Helmholtz says, “The agreement between our
visual perceptions and the external world, rests, at least in the most
important matters, on the same ground that all our knowledge of the
actual world rests on, upon the experience and the lasting test of their
correctness by means of experiments, i.e., of the movements of our
bodies.” This would almost make it seem that the supreme judge among the
senses is the touch. But that is not intended; we know well enough to
what illusions we are subject if we trust the sense of touch alone. At
the same time we must suppose that the question here is one of the
nature of the body, and this can be measured only by something similar,
i.e., by our own physical characteristics, but always under the control
of some other sense, especially the sense of sight.
The visual process itself consists, according to Fischer, “of a
compounded series of results which succeed each other with extraordinary
rapidity and are causally related. In this series the following elements
may principally be distinguished.
(1) The physico-chemical process.
(2) The physiologico-sensory.
(3) The psychological.
(4) The physiologico-motor.
(5) The process of perception.”
It is not our task to examine the first four elements. In order clearly
to understand the variety of perception, we have to deal with the last
only. I once tried to explain this by means of the phenomenon of
instantaneous photographs (cinematographs). If we examine one such
representing an instant in some quick movement, we will assert that we
never could have perceived it in the movement itself. This indicates
that our vision is slower than that of the photographic apparatus, and
hence, that we do not apprehend the smallest particular conditions, but
that we each time unconsciously compound a group of the smallest
conditions and construct in that way the so-called instantaneous
impressions. If we are to compound a great series of instantaneous
impressions in one galloping step, we must have condensed and compounded
a number of them in order to get the image that we see with our eyes as
instantaneous. We may therefore say that the least instantaneous image
we ever see with our eyes contains many parts which only the
photographic apparatus can grasp. Suppose we call these particular
instances a, b, c, d, e, f, g, h, i, j, k, l, m; it is self-evident that
the manner of their composition must vary with each individual. One man
may compound his elements in groups of three: a, b, c,--d, e, f,--g, h,
i, etc.; another may proceed in dyads: a, b,--c, d,--e, f,--g, h,--etc.;
a third may have seen an unobservable instant later, but constructs his
image like the first man: b, c, d,--l, m, n, etc.; a fourth works slowly
and rather inaccurately, getting: a, c, d,--f, h, i,--etc. Such
variations multiply, and when various observers of the same event
describe it they do it according to their different characteristics. And
the differences may be tremendous. Substitute numerals for letters and
the thing becomes clear. The relative slowness of our apprehension of
visual elements has the other consequence that we interpolate objects in
the lacunæ of vision _according to our expectations_. The best example
of this sort of thing would be the perception of assault and battery.
When ten people in an inn see how A raises a beer glass against B’s
head, five expect: “Now he’ll pound him,” and five others: “Now he’ll
throw it.” If the glass has reached B’s head none of the ten observers
have seen how it reached there, but the first five take their oath that
A pounded B with the glass, and the other five that he threw it at B’s
head. And all ten have really seen it, so firmly are they convinced of
the correctness of their swift judgment of expectation. Now, before we
treat the witness to some reproach like untruth, inattention, silliness,
or something equally nice, _we_ had better consider whether his story is
not true, and whether the difficulty might not really lie in the
imperfection of our own sensory processes. This involves partly what
Liebmann has called “anthropocentric vision,” i.e., seeing with man as
the center of things. Liebmann further asserts, “that we see things only
in perspective sizes, i.e., only from an angle of vision varying with
their approach, withdrawal and change of position, but in no sense as
definite cubical, linear, or surface sizes. The apparent size of an
object we call an angle of vision at a certain distance. But, what
indeed is the different, true size? We know only relations of
magnitude.” This description is important when we are dealing with
testimony concerning size. It seems obvious that each witness who speaks
of size is to be asked whence he had observed it, but at the same time a
great many unexpected errors occur, especially when what is involved is
the determination of the size of an object in the same plane. One need
only to recall the meeting of railway tracks, streets, alleys, etc., and
to remember how different in size, according to the point of view of the
witness, various objects in such places must appear. Everybody knows
that distant things seem smaller than near ones, but almost nobody knows
what the difference amounts to. For examples see Lotze, “Medical
Psychology,” Leipzig, 1852.
In addition we often think that the clearness of an object represents
its distance and suppose that the first alone determines the latter. But
the distinctness of objects, i.e., the perceptibility of a
light-impression, depends also upon the absolute brightness and the
differences in brightness. The latter is more important than is
supposed. Try to determine how far away you can see a key-hole when the
wall containing the door is in the shadow, and when there is a window
opposite the key-hole. A dark object of the size of a key-hole will not
be visible at one hundredth of the distance at which the key-hole is
perceived. Moreover, the difference in intensity is not alone in
consideration; the intensity of the object _with regard to its
background_ has yet to be considered. Aubert has shown that the accuracy
of the distinction is the same when a square of white paper is looked at
from an angle of 18´´, and when conversely a square of black paper on
white background is looked at from an angle of 35´´. “When we put a gray
paper in the sunshine, it may become objectively brighter than white
paper in shadow. But this does not prevent us from knowing one as gray
and the other as pure white. We separate the color of the object from
the intensity of the incident light.” But this is not always so simple,
inasmuch as we know in the case in hand which paper is gray and which
white, which is in the sunlight and which in the shadow. But if these
facts are not known mistakes often occur so that a man dressed in dark
clothes but in full light will be described as wearing lighter clothes
than one who wears light clothes in the shadow.
Differences of illumination reveal a number of phenomena difficult to
explain. Fechner calls attention to the appearance of stars: “At night
everybody sees the stars, in daylight not even Sirius or Jupiter is
seen. Yet the absolute difference between those places in the heavens
where the stars are and the environing places is just as great as in the
night--there is only an increase in illumination.” Of still greater
importance to us is the circumstance noted but not explained by
Bernstein. If, in daylight, we look into a basement room from outside,
we can perceive nothing, almost; everything is dark, even the windows
appear black. But in the evening, if the room is ever so slightly
illuminated, and we look into it from outside, we can see even small
articles distinctly. Yet there was much intenser light in the room in
question during the day than the single illumination of the night could
have provided. Hence, it is asserted, the difference in this case is a
standard one. In open day the eye is accustomed to the dominating
brightness of daylight, beside which the subdued illumination of the
room seems relatively dark. But in the evening one is in the dark, and
hence even the little light of a single candle is enough to enable one
to see. That this explanation is untrue is shown by the fact that the
phenomenon is not regulated even when the circumstances in question are
made identical. If, for example, you approach the window in daylight
with your eyes shut, lean your forehead against the pane and shut out
the light on the sides with your hands, and then open your eyes, you see
as little in the room as when you looked into it without performing this
ceremony. So again, if during the night you gazed at some near-by gas
lamp and then glanced into the room, there is only a few moments’
indistinctness at most, after that the single candle is enough. The
reason, then, must be different from the assigned one--but whatever it
is, we need only to maintain that immediate judgment concerning numerous
cases involving situations of this kind would be overhasty. It is often
said that a witness was able to see this or that under such and such
illumination, or that he was unable to see it, although he denies his
ability or inability. The only solution of such contradictions is an
experiment. The attempt must be made either by the judge or some
reliable third person, to discover whether, under the same conditions
of illumination, anything could be seen at the place in question or not.
As to _what_ may be seen in the distance, experiment again, is the best
judge. The human eye is so very different in each man that even the
acute examination into what is known of the visual image of the Pleiades
shows that the _average_ visual capacity of classic periods is no
different from our own, but still that there was great variety in visual
capacity. What enormous visual power is attributed to half-civilized and
barbarous peoples, especially Indians, Esquimos, etc.! Likewise among
our own people there are hunters, mountain guides, etc., who can see so
clearly in the distance that mere stories about it might be fables. In
the Bosnian campaign of 1878 we had a soldier who in numerous cases of
our great need to know the enemy’s position in the distance could
distinguish it with greater accuracy than we with our good
field-glasses. He was the son of a coal-miner in the Styrian mountains,
and rather a fool. Incidentally it may be added that he had an
incredible, almost animal power of orientation.
As we know little concerning far-sightedness, so also we are unable to
define what near-sighted people can see. Inasmuch as their vision does
not carry, they are compelled to make intellectual supplementations.
They observe the form, action, and clothes of people more accurately
than sharp-eyed persons, and hence recognize acquaintances at a greater
distance than the latter. Therefore, before an assertion of a
short-sighted man is doubted an experiment should be made, or at least
another trustworthy short-sighted person should be asked for his
opinion.
The background of objects, their movement and form have decided effects
on the difference in visual perception. It is an ancient observation
that lengthy objects like poles, wires, etc., are visible at
incomparably greater distances than, e.g., squares of the same length.
In examination it has been shown that the boundary of accurate
perception can hardly be determined. I know a place where under
favorable illumination taut, white and very thin telephone wires may be
seen at a distance of more than a kilometer. And this demands a very
small angle of vision.
Humboldt calls attention to the large number of “optical fables.” He
assures us that it is certainly untrue that the stars may be seen in
daylight from a deep well, from mines, or high mountains, although this
has been repeatedly affirmed since Aristotle.
The explanation of our power to see very thin, long objects at a very
great distance, is not our affair, but is of importance because it
serves to explain a number of similar phenomena spoken of by witnesses.
We have either incorrectly to deny things we do not understand, or we
have to accept a good deal that is deniable. We will start, therefore,
with the well-known fact that a point seen for a considerable time may
easily disappear from perception. This has been studied by Helmholtz and
others, and he has shown how difficult it is to keep a point within the
field of vision for only ten or twenty minutes. Aubert examines older
studies of the matter and concludes that this disappearance or confusion
of an object is peripheral, but that fixation of a small object is
always difficult. If we fix a distant point it is disappearing at every
instant so that an accurate perception is not possible; if however we
fix upon a long, thin body, e.g., a wire, it is unnecessary to fix a
single point and we may see the object with a wandering eye, hence more
clearly.
Helmholtz adds that weakly objective images disappear like a wet spot on
warm tin, at the moment a single point is fixed, as does e.g., a
landscape seen at night. This last acute observation is the basis of
many a testimony concerning the sudden disappearance of an object at
night. It has helped me in many an examination, and always to advantage.
In this connection the over-estimation of the moon’s illuminating power
is not to be forgotten. According to Helmholtz the power of the full
moon is not more than that of a candle twelve feet away. And how much
people claim to have seen by moonlight! Dr. Vincent[178] says that a man
may be recognized during the first quarter at from two to six meters, at
full moon at from seven to ten meters, and at the brightest full moon,
an intimate may be recognized at from fifteen to sixteen meters. This is
approximately correct and indicates how much moonlight is
over-estimated.
In addition to the natural differences of sight there are also those
artificially created. How much we may help ourselves by skilful
distinctions, we can recognize in the well-known and
frequently-mentioned business of reading a confused handwriting. We aim
to weaken our sense-perception in favor of our imagination, i.e. so to
reduce the clearness of the former as to be able to test upon it in some
degree a larger number of images. We hold the MS. away from us, look at
it askant, with contracted eyebrows, in different lights, and finally we
read it. Again, the converse occurs. If we have seen something with a
magnifying glass we later recognize details without its help. Definite
conditions may bring to light very great distinctions. A body close to
the face or in the middle distance looks different according as one eye
or both be used in examining it. This is an old story and explains the
queer descriptions we receive of such objects as weapons and the like,
which were suddenly held before the face of the deponent. In cases of
murderous assault it is certain that most uncanny stories are told,
later explained by fear or total confusion or intentional dishonesty,
but really to be explained by nothing more than actual optical
processes.
I do not believe that binocular vision is of much importance in the law;
I know of no case in ordinary vision where it matters whether one or
both eyes have been used. It is correct to assert that one side or the
other of a vertically held hand will be clearer if, before looking at it
with both eyes, you look at it with one or the other, but this makes
little difference to our purpose. It must be maintained that a part of
what we see is seen with one eye only,--if, e.g., I look at the sky and
cover one eye with my hand, a certain portion of the heaven disappears,
but I observe no alteration in the remaining portion. When I cover the
other eye, other stars disappear. Therefore, in binocular vision certain
things are seen with one eye only. This may be of importance when an
effect has been observed first with both eyes, then with one; raising
the question of the difference in observation--but such a question is
rare.
There are two additional things to consider. The first is the problem of
the influence of custom on increasing visual power in darkness. This
power is as a rule undervalued. No animal, naturally, can see anything
in complete darkness. But it is almost unbelievable how much can be seen
with a very little light. Here again, prisoners tell numerous stories
concerning their vision in subterranean prisons. One saw so well as to
be able to throw seven needles about the cell and then to find them
again. Another, the naturalist Quatremére-Disjonval, was able so
accurately to observe the spiders in his cell as to make the observation
the basis for his famous “Aranéologie.” Aubert tells of his having had
to stay in a room so dark as to make it necessary for others to feel
their way, but nevertheless being able to read books without detection
because the others could not see the books.
How quickly we get used to darkness and how much more we see after a
while, is well known. It is also certain that the longer you are in
darkness the more you see. You see more at the end of a day than after a
few hours, and at the end of a year, still more. The eye, perhaps,
changes in some degree for just this purpose. But a prolonged use of the
visual mechanism tends to hypertrophy--or atrophy, as the eyes of
deep-sea fishes show. It is well, in any event, to be careful about
contradicting the testimonies of patients who have long lived in the
dark, concerning what they have seen. The power to see in the dark is so
various that without examination, much injustice may be done. Some
people see almost nothing at twilight, others see at night as well as
cats. And in court these differences must be established and
experimentally verified.
The second important element is the innervation of the muscles in
consequence of movement merely seen. So Stricker points out, that the
sight of a man carrying a heavy load made him feel tension in the
muscles involved, and again, when he saw soldiers exercising, he almost
was compelled openly to act as they. In every case the muscular
innervation followed the visual stimulus.
This may sound improbable but, nevertheless, everybody to some degree
does the identical things. And at law the fact may be of importance in
cases of assault and battery. Since I learned it, I have repeatedly
observed in such cases, from harmless assault to murder, that people,
although they had not been seen to deal any blows, were often accused of
complicity simply because they were making suspicious movements that led
to the following inference: “They stuck their hands into their trousers
pocket looking for a knife, clenched their fists, looked as if they were
about to jump, swung their hands.” In many such cases it appeared that
the suspects were harmless spectators who were simply more obvious in
their innervation of the muscles involved in the assault they were
eagerly witnessing. This fact should be well kept in mind; it may
relieve many an innocent.