The Story of the Mind

J >> James Mark Baldwin >> The Story of the Mind

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Second, many experts agree that diseases of the mind, whatever their
brain seat may be, all involve impairment of the Attention. This, at
any rate, is a general mark of a deranged or defective mind. The idiot
lacks power of attention. The maniac lacks control of his attention.
The deluded lacks grasp and flexibility of attention. The crank can
only attend to one thing. The old man is feeble in the attention,
having lost his hold. So it goes. The attention is the instrument of
the one sort of normal mental activity called Apperception, and so
impairment of the attention shows itself at once in some particular
form of defect.

Third, it is interesting to know that in progressive mental failure
the loss of the powers of the mind takes place in an order which is
the reverse of that of their original acquisition. The most complex
functions, which are acquired last, are the first to show impairment.
In cases of general degeneration, softening of the brain, etc., the
intelligence and moral nature are first affected, then memory,
association, and acquired actions of all sorts, while there remain,
latest of all, actions of the imitative kind, most of the deep-set
habits, and the instinctive, reflex, and automatic functions, This
last condition is seen in the wretched victim of dementia and in the
congenital idiot. The latter has, in addition to his life processes
and instincts, little more than the capacity for parrot-like
imitation. By this he acquires the very few items of his education.

The recovery of the patient shows the same stages again, but in the
reversed direction; he pursues the order of the original acquisition,
a process which physicians call Re-evolution.

CHAPTER VI.

HOW WE EXPERIMENT ON THE MIND--EXPERIMENTAL PSYCHOLOGY.

In recent years the growth of the method of experimenting with bodies
in laboratories in the different sciences has served to raise the
question whether the mind may not be experimented with also. This
question has been solved in so far that psychologists produce
artificial changes in the stimulations to the senses and in the
arrangements of the objects and conditions existing about a person,
and so secure changes also in his mental states. What we have seen of
Physiological Psychology illustrates this general way of proceeding,
for in such studies, changes in the physiological processes, as in
breathing, etc., are considered as causing changes in the mind. In
Experimental Psychology, however, as distinguished from Physiological
Psychology, we agree to take only those influences which are outside
the body, such as light, sound, temperature, etc., keeping the subject
as normal as possible in all respects.

A great many laboratories have now been established in connection with
the universities in Germany, France, and the United States. They
differ very much from one another, but their common purpose is so to
experiment upon the mind, through changes in the stimulations to which
the individual is subjected, that tests may be made of his sensations,
his ability to remember, the exactness and kind of movements, etc.

The working of these laboratories and the sort of research carried out
in them may be illustrated best, perhaps, by a description of some of
the results, apparatus, methods, etc., employed in my own laboratory
during the past year. The end in view will, I trust, be considered
sufficient justification for the degree of personal reference which
this occasions; since greater concreteness and reality attach to
definite descriptions such as this. The other laboratories, as those
at Harvard and Columbia Universities, take up similar problems by
similar methods. I shall therefore go on to describe some recent work
in the Princeton laboratory.

Of the problems taken up in the laboratory, certain ones may be
selected for somewhat detailed explanation, since they are from widely
different spheres and illustrate different methods of procedure.

I. _Experiments on the Temperature Sense._--For a score of years it
has been suspected that we have a distinct sense, with a nerve
apparatus of its own, for the feeling of different temperatures on the
skin. Certain investigators found that this was probably true; it is
proved by the fact that certain drugs alter the sensibility of the
skin to hot and cold stimulations.

Another advance was made when it was found that sensations of either
hot or cold may be had from regions which are insensible at the same
time to the other sort of stimulation, cold or hot. Certain minute
points were discovered which report cold when touched with a cold
point, but give no feeling from a hot object; while other points would
respond only with a sensation from heat, never giving cold. It was
concluded that we have two temperature senses, one for hot and the
other for cold.

Taking the problem at this point, Mr. C.[3] wished to define more
closely the relation of the two sorts of sensation to each other, and
thought he could do so by a method by which he might repeat the
stimulation of a series of exact spots, very minute points on the
skin, over and over again, thus securing a number of records of the
results for both hot and cold over a given area. He chose an area of
skin on the forearm, shaved it carefully, and proceeded to explore it
with the smallest points of metals which could be drawn along the skin
without pricking or tearing. These points were attached to metallic
cylinders, and around the cylinders rubber bands were placed; the
cylinders were then thrust in hot or cold water kept at certain
regular temperatures, and lifted by the rubber bands. They were placed
point down, with equal pressure, upon the points of the skin in the
area chosen. In this way, points which responded only to hot, and also
those responding only to cold, were found, marked with delicate ink
marks in each case, until the whole area was explored and marked in
different colours. This had often been done before. It remained to
devise a way of keeping these records, so that the markings might all
be removed from the skin, and new explorations made over the same
surface. This was necessary in order to see whether the results
secured were always the same. The theory that there were certain
nervous endings in the skin corresponding to the little points
required that each spot should be in exactly the same place whenever
the experiment was repeated.

[Footnote 3: Mr. J. F. Crawford, graduate student.]

Mr. C. made a number of so-called "transparent transfer frames." They
are rectangular pieces of cardboard, with windows cut in them. The
windows are covered with thin architect's paper, which is very
transparent. This frame is put over the forearm in such a way that the
paper in the window comes over the markings made on the arm. The
markings show through very clearly, and the points are copied on the
paper. Then certain boundary marks at the corners are made, both on
the paper and on the arm, at exactly the same places, the frame is
removed, and all the markings on the arm are erased except the
boundary points. The result is that at any time the frames can be put
over the arm again by matching the boundary points, and then the
original temperature spots on the skin will be shown by the markings
on the paper window.

Proceeding to repeat the exploration of the same area in this way, Mr.
C makes records of many groupings of points for both hot and cold
sensations on the same area; he then puts the frames one upon another,
holds them up before a window so that they have a bright background,
and is thus able to see at a glance how nearly the results of the
different sittings correspond.

His results, put very briefly, fail to confirm the theory that the
sense of temperature has an apparatus of fixed spots for heat and
other fixed spots for cold. For when he puts the different markings
for heat together he finds that the spots are not the same, but that
those of one frame fall between those of another, and if several are
put together the points fill up a greater or smaller area. The same
for the cold spots; they fill a continuous area. He finds, however, as
other investigators have found, that the heat areas are generally in
large measure separate from the cold areas, only to a certain extent
overlapping here and there, and also that there are regions of the
skin where we have very little sense of either sort of temperature.

The general results will show, therefore, if they should be confirmed
by other investigators, that our temperature sense is located in what
might be called somewhat large blotches on the skin, and not in minute
spots; while the evidence still remains good, however, to show that we
have two senses for temperature, one for cold and the other for hot.

II. _Reaction-Time Experiments._--Work in so-called "reaction times"
constitutes one of the most important and well-developed chapters in
experimental psychology. In brief, the experiment involved is this:
To find how long it takes a person to receive a sense impression of
any kind--for example, to hear a sound-signal--and to move his hand or
other member in response to the impression. A simple arrangement is as
follows: Sit the subject comfortably, tap a bell in such a way that
the tapping also makes an electric current and starts a clock, and
instruct the subject to press a button with his finger as soon as
possible after he hears the bell. The pressing of the button by him
breaks the current and stops the clock. The dial of the clock
indicates the actual time which has elapsed between the bell (signal)
and his response with his finger (reaction). The clock used for exact
work is likely to be the Hipp chronoscope, which gives on its dials
indications of time intervals in thousandths of a second. For the sake
of keeping the conditions constant and preventing disturbance, the
wires are made long, so that the clock and the experimenter may be in
one room, while the bell, the punch key, and the subject are in
another, with the door closed. This method of getting reaction times
has been in use for a number of years, especially by the astronomers
who need to know, in making their observations, how much time is taken
by the observer in recording a transit or other observation. It is
part of the astronomer's "personal equation."

Proceeding with this "simple-reaction" experiment as a basis, the
psychologists have varied the instructions to the subject so as to
secure from him the different times which he takes for more
complicated mental processes, such as distinguishing between two or
more impressions, counting, multiplying, dividing, etc., before
reacting; or they have him wait for an associated idea to come up
before giving his response, with many other variations. By comparing
these different times among themselves, interesting results are
reached concerning the mental processes involved and also about the
differences of different individuals in the simpler operations of
their daily lives. The following research carried out by Mr. B.[4]
serves to illustrate both of these assertions.

[Footnote 4: The writer.]

Mr. B. wished to inquire further into a fact found out by several
persons by this method: the fact that there is an important difference
in the length of a person's reaction time according to the direction
of his attention during the experiment. If, for example, Mr. X. be
tested, it is possible that he may prefer to attend strictly to the
signal, letting his finger push the key without direct care and
supervision. If this be true, and we then interfere with his way of
proceeding, by telling him that he must attend to his finger, and
allow the signal to take care of itself, we find that he has great
difficulty in doing so, grows embarrassed, and his reaction time
becomes very irregular and much longer. Yet another person, say Y, may
show just the opposite state of things; he finds it easier to pay
attention to his hand, and when he does so he gets shorter and also
more regular times than when he attends to the signal-sound.

It occurred to Mr. B. that the striking differences given by different
persons in this matter of the most favourable direction of the
attention might be connected with the facts brought out by the
physiological psychologists in connection with speech; namely, that
one person is a "visual," in speaking, using mainly sight images of
words, while another is a "motor," using mainly muscular images, and
yet another an "auditive," using mainly sound images. If the
differences are so marked in the matter of speech, it seemed likely
that they might also extend to other functions, and the so-called
"type" of a person in his speech might show itself in the relative
lengths of his reaction times according as he attended to one class of
images or another.

Calling this the "type theory" of reaction times, and setting about
testing four different persons in the laboratory, the problem was
divided into two parts; first, to direct all the individuals selected
to find out, by examining their mental preferences in speaking,
reading, writing, dreaming, etc., the class of images which they
ordinarily depended most upon; and then to see by a series of
experiments whether their reaction times to these particular classes
of images were shorter than to others, and especially whether the
times were shorter when attention was given to these images than when
it was given to the muscles used in the reactions. The meaning of this
would be that if the reaction should be shorter to these images than
to the corresponding muscle images, or to the other classes of images,
then the reaction time of an individual would show his mental type and
be of use in testing it. This would be a very important matter if it
should hold, seeing that many questions both in medicine and in
education, which involve the ascertaining of the mental character of
the individual person, would profit by such an exact method.

The results on all the subjects confirmed the supposition. For
example, one of them, Mr. C., found from an independent examination of
himself, most carefully made, that he depended very largely upon his
hearing in all the functions mentioned. When he thought of words, he
remembered how they sounded; when he dreamed, his dreams were full of
conversation and other sounds. When he wrote, he thought continually
of the way the words and sentences would sound if spoken. Without
knowing of this, many series of reaction experiments were made on him;
the result showed a remarkable difference between the lengths of his
reactions, according as he directed his attention to the sound or to
his hand; a difference showing his time to be one half shorter when he
paid attention to the sound. The same was seen when he reacted to
lights; the attention went preferably to the light, not to the hand;
but the difference was less than in the case of sounds. So it was an
unmistakable fact in his case that the results of the reaction
experiments agreed with his independent decision as to his mental
type.

In none of the cases did this correspondence fail, although all were
not so pronounced in their type preferences as was Mr. C.

The second part of the research had in view the question whether
reaction times taken upon speech would show the same thing; that is,
whether in Mr. C.'s case, for example, it would be found that his
reaction made by speaking, as soon as he heard the signal or saw the
light, would be shorter when he paid attention to the signal than when
he gave attention to his mouth and lips. For this purpose a mouth key
was used which made it possible for the subject simply by emitting a
puff of breath from the lips, to break an electric current and thus
stop the chronoscope as soon as possible after hearing the signal.
The mouth key is figured herewith (Fig. 6).

[Illustration: FIG. 6.--Mouth-key (Isometric drawing) The metallic
tongue E swings over the mercury H, making or breaking the circuit A H
E D B or C E H A. The tongue is moved by a puff of air through the
funnel F. (Devised by Prof. W. Libbey.)]

This experiment was also carried out on all the subjects, none of them
having any knowledge of the end in view, and the experimenters also
not having, as yet, worked out the results of the earlier research. In
all the cases, again, the results showed that, for speech, the same
thing held as for the hand--namely, that the shortest reaction times
were secured when the subject paid attention to the class of images
for which he had a general preference. In Mr. C.'s case, for example,
it was found that the time it took him to speak was much shorter when
he paid strict attention to the expected sound than when he attended
to his vocal organs. So for the other cases. If the individual's
general preference is for muscular images, we find that the quickest
time is made when attention is given to the mouth and lips. Such is
the case with Mr. B.

The general results go to show, therefore--and four cases showing no
exception, added to the indications found by other writers, make a
general conclusion very probable--that in the differences in reaction
times, as secured by giving the attention this way or that, we have
general indications of the individual's temperament, or at least of
his mental preferences as set by his education. These indications
agree with those found in the cases of aphasia known as "motor,"
"visual," "auditory," etc., already mentioned. The early examination
of children by this method would probably be of great service in
determining proper courses of treatment, subjects of study, modes of
discipline, tendencies to fatigue and embarrassment, and the direction
of best progress in education.

This research may be taken to illustrate the use of the reaction-time
method in investigating such complex processes as attention,
temperament, etc. The department which includes the various time
measurements in psychology is now called Mental Chronometry, the older
term, Psychometry, being less used on account of its ambiguity.

III. _An Optical Illusion._--In the sphere of vision many very
interesting facts are constantly coming to light. Sight is the most
complex of the senses, the most easily deranged, and, withal, the most
necessary to our normal existence. The report of the following
experimental study will have the greater utility, since, apart from
any intrinsic novelty or importance the results may prove to have, it
shows some of the general bearings of the facts of vision in relation
to AEsthetics, to the theory of Illusions, and to the function of
Judgment.

Illusion of the senses is due either to purely physiological causes or
to the operation of the principle of Assimilation, which has already
been remarked upon. In the latter case it illustrates the fact that at
any time there is a general disposition of the mind to look upon a
thing under certain forms, patterns, etc., to which it has grown
accustomed; and to do this it is led sometimes to distort what it sees
or hears unconsciously to itself. So it falls into errors of judgment
through the trap which is set by its own manner of working. Nowhere is
the matter better illustrated than in the sphere of vision. The number
of illusions of vision is remarkable. We are constantly taking shapes
and forms for something slightly different from what, by measurement,
we actually find them to be. And psychologists are attempting--with
rather poor success so far--to find some general principles of the
mechanism of vision which will account for the great variety of its
illusions.

Among these principles one is known as Contrast. It is hardly a
principle as yet. It is rather a word used to cover all illusions
which spring up when surfaces of different sizes and shapes, looked at
together or successively, are misjudged with reference to one another.
Wishing to investigate this in a simple way, the following experiment
was planned and carried out by Mr. B.

He wished to find out whether, if two detached surfaces of different
sizes be gazed at together, the linear distances of the field of
vision (the whole scene visible at once) would be at all misjudged. To
test this, he put in the window (W)[5] of the dark room a filling of
white cardboard in which two square holes had been cut (S S'). The
sides of the squares were of certain very unequal lengths. Then a slit
was made between the middle points of the sides of the squares next to
each other, so that there was a narrow path or trough joining the
squares between their adjacent sides. Inside the dark room he arranged
a bright light so that it would illuminate this trough, but not be
seen by a person seated some distance in front of the window in the
next room. A needle (D) was hung on a pivot behind the cardboard, so
that its point could move along the bright trough in either direction;
and on the needle was put the armature (A) of an electro-magnet which,
when a current passed, would be drawn instantly to the magnet (E), and
so stop the needle exactly at the point which it had then reached. A
clock motor (Cm) was arranged in such a way as to carry the needle
back and forth regularly over the slit; and the electro-magnet was
connected by wires with a punch key (K) on a table beside the subject
in the next room. All being now ready, the subject, Mr. S., is told to
watch the needle which appears as a bead of light travelling along the
slit, and stop it when it comes to the middle point of the line, by
pressing the electric key. The experimenter, who stands behind the
window in the dark room, reads on a scale (mm.) marked in millimetres
the exact point at which the needle stops, releases the needle by
breaking the current, thus allowing it to return slowly over the line
again. This gives the subject another opportunity to stop it at what
he judges to be the exact middle of the line, and so on. The
accompanying figure (Fig. 7) shows the entire arrangement.

[Footnote 5: This and the following letters in parentheses refer to
Fig. 7]

[Illustration: FIG. 7]

A great many experiments performed in this way, with the squares set
both vertically and horizontally, and with several persons, brought a
striking and very uniform result. The point selected by the subject as
the middle is regularly too far toward the smaller square. Not a
little, indeed, but a very appreciable amount. The amount of the
displacement, or, roughly speaking, of the illusion, increases as the
larger square is made larger and the smaller one smaller; or, put in a
sentence, the amount varies directly with the ratio of the smaller to
the larger square side.

Finding such an unmistakable illusion by this method, Mr. B. thought
that if it could be tested by an appeal to people generally, it would
be of great gain. It occurred to him that the way to do this would be
to reverse the conditions of the experiment in the following way: He
prepared the figures given in Plate I, in which the two squares are
made of suitable relative size, a line is drawn between them, and a
point on the line is plainly marked. This he had printed in a weekly
journal, and asked the readers of the journal to get their friends,
after merely looking at the figure (i. e., without knowing the result
to be expected), to say--as the reader may now do before reading
further--whether the point on the line (Plate I) is in the middle or
not; and if not, in which direction from the true middle it lies. The
results from hundreds of persons of all manner of occupations, ages,
and of both sexes, agree in saying that the point lies too far toward
the larger square. In reality it is in the exact middle. This is just
the opposite of the result of the experiments in the laboratory, where
the conditions were the reverse, i. e., to find the middle as it
appears to the eye. Here, therefore, we have a complete confirmation
of the illusion; and it is now fully established that in all cases in
which the conditions of this experiment are realized we make a
constant mistake in estimating distances by the eye.[6]

[Footnote 6: In redrawing the figure on a larger sheet (which is
recommended), the connecting line may be omitted, only the mid-point
being marked. Some get a better effect with two circles, the
intervening distance being divided midway by a dot, as in Plate II.]

For instance, if a town committee wish to erect a statue to their
local hero in the public square, and if on two opposite sides of the
square there are buildings of very different heights, the statue
should not be put in the exact middle of the square, if it is to give
the best effect from a distance. It should be placed a little toward
the smaller building. A colleague of the writer found, when this was
first made public, that the pictures in his house had actually been
hung in such a way as to allow for this illusion. Whenever a picture
was to be put up between two others of considerable difference of
size, or between a door (large) and a window (small), it had actually
been hung a little nearer to the smaller--toward the small picture or
toward the window--and not in the true middle.

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