The high standing of the sense of touch which make it in certain
directions even the organ of control of the sense of sight, is well
known, and Condillac’s historic attempt to derive all the senses from
this one is still plausible. If what is seen is to be seen accurately
there is automatic resort to the confirmatory aid of the sense of touch,
which apprehends what the eye has missed. Hence we find many people
touching things, whose vision is not altogether reliable--i.e., people
of considerable age, children unpracticed in seeing, an uneducated
people who have never learned to see quickly and comprehensively.
Moreover, certain things can be determined only by touching, i.e., the
fineness of papers, cloth, etc., the sharpness or pointedness of
instruments, or the rawness of objects. Even when we pat a dog kindly we
do so partly because we want to see whether his skin is as smooth and
fine as the eye sees it; moreover, we want to test the visual impression
by that of touch.
But important and reliable as the sense of touch is, it is nevertheless
not to be trusted when it is the sole instrument of perception. We must
never depend on the testimony of a witness based entirely on perceptions
by touch, and the statements of a wounded person concerning the time,
manner, etc., of his wound are unreliable unless he has also seen what
he has felt. We know that most knife and bullet wounds, i.e., the most
dangerous ones, are felt, in the first instance, as not very powerful
blows. Blows on the extremities are not felt as such, but rather as
pain, and blows on the head are regularly estimated in terms of pain,
and falsely with regard to their strength. If they were powerful enough
to cause unconsciousness they are said to have been very massive, but if
they have not had that effect, they will be described by the most honest
of witnesses as much more powerful than they actually were. Concerning
the location of a wound in the back, in the side, even in the upper arm,
the wounded person can give only general indications, and if he
correctly indicates the seat of the wound, he has learned it later but
did not know it when it occurred. According to Helmholtz, practically
all abdominal sensations are attributed to the anterior abdominal wall.
Now such matters become of importance when an individual has suffered
several wounds in a brawl or an assault and wants to say certainly that
he got wound A when X appeared, wound B when Y struck at him, etc. These
assertions are almost all false because the victim is likely to identify
the pain of the moment of receiving the wound with its later
painfulness. If, for example, an individual has received a rather long
but shallow knife wound and a deep stab in the back, the first will
cause him very considerable burning sensation, the latter only the
feeling of a heavy blow. Later on, at the examination, the cut has
healed and is no longer painful; the dangerous stab which may have
reached the lung, causes pain and great difficulty in breathing, so that
the wounded man assigns the incidence of the stab to the painful
sensation of the cut, and conversely.
Various perceptions of victims on receiving a wound are remarkable, and
I have persuaded a police surgeon of considerable learning and
originality to collect and interpret his great mass of material. It is
best done by means of tabulation, accurate description of wounds
according to their place, size, form, and significance, the statement of
the victim concerning his feeling at the moment of receiving the wound,
the consequences of healing, and at the end explanatory observations
concerning the reasons for true or incorrect sensations of the victim.
As this work is to have only psychological value it is indifferent
whether the victim is veracious or not. What we want to know is what
people say about their perception. The true and the false will
distinguish themselves automatically, the material being so rich, and
the object will be to compare true subjective feelings with true
subjective deeds. Perhaps it may even be possible to draw
generalizations and to abstract certain rules.
There are many examples of the fact that uncontrolled touch leads to
false perceptions. Modern psychophysics has pointed to a large group of
false perceptions due to illusions of pressure, stabs, or other contact
with the skin. The best known, and criminalistically most important
experiments, are those with open compasses. Pressed on the less
sensitive parts of the body, the back, the thigh, etc., they are always
felt as one, although they are quite far apart. The experiments of
Flournoy, again, show how difficult it is to judge weights which are not
helped by the eye’s appreciation of their form and appearance. Ten
objects of various forms were judged by fifty people for their weight;
only one discovered that they all had the same weight.
Similarly, mere touch can not give us proper control over the organs of
the body. Sully says that in bed we may voluntarily imagine that a leg
has a position quite different from that it really has. Let me cite some
similar examples from my “Manual for Investigating Judges.” If we take a
pea between the thumb and the index finger, we feel the pea simply,
although its tactile image comes to us through two fingers, i.e.,
double. If now we cross the third finger over the fourth and hold the
pea between the ends of these two fingers, we feel it to be double
because the fingers are not in their customary positions and hence give
double results. From one point of view this double feeling is correct,
but when we touch the pea naturally, experience helps us to feel only
one pea. Another example consists in crossing the hands and turning them
inward and upward, so that the left fingers turn to the left and the
right fingers to the right. Here the localization of the fingers is
totally lost, and if a second person points to one of the fingers
without touching it, asking you to lift it, you regularly lift the
analogous finger of the other hand. This shows that the tactile sense is
not in a very high stage of development, since it needs, when unhelped
by long experience, the assistance of the sense of sight. Perceptions
through touch alone, therefore, are of small importance; inferences are
made on the basis of few and more coarse characteristic impressions.
This is shown by a youthful game we used to play. It consisted of
stretching certain harmless things under the table--a soft piece of
dough, a peeled, damp potato stuck on a bit of wood, a wet glove filled
with sand, the spirally cut rind of a beet, etc. Whoever got one of
these objects without seeing it thought he was holding some disgusting
thing and threw it away. His sense of touch could present only the
dampness, the coldness, and the motion, i.e., the coarsest traits of
reptilian life, and the imagination built these up into a reptile and
caused the consequent action. Foolish as this game seems, it is
criminalistically instructive. It indicates what unbelievable illusions
the sense of touch is capable of causing. To this inadequacy of the
tactile imagination may be added a sort of transferability of certain
touch sensations. For example, if ants are busy near my seat I
immediately feel that ants are running about under my clothes, and if I
see a wound or hear it described, I often feel pain in the analogous
place on my own body. That this may lead to considerable illusion in
excitable witnesses is obvious.
Finally, this dependence of the sense of touch may be supplemented by
the fact that it is counted only relatively, and its value varies with
the individual. We find the cellar warm in winter and cold in summer,
because we only feel the difference with the outer air, and when we put
one hand in hot, and the other in cold water, and then put both in tepid
water one finds the tepid water cold, the other warm. The record of
tactile sensations is frequent in our protocols and requires constant
consideration of the sense’s unreliability.
Diseased conditions are of course to be referred to the physician. I
need only mention that slight poisonings by means of chloroform,
morphine, atropine, daturine, decrease, and that strychnine increases
the sensitivity of the touch organ.