The Mind and Its Education

G >> George Herbert Betts >> The Mind and Its Education

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Thus ether waves at the rate of 450 billions a second give us the
sensation of red; of 472 billions a second, orange; of 526 billions a
second, yellow; of 589 billions a second, green; of 640 billions a
second, blue; of 722 billions a second, indigo; of 790 billions a
second, violet. What exists outside of us, then, is these ether waves of
different rates, and not the colors (as sensations) themselves. The
beautiful yellow and crimson of a sunset, the variegated colors of a
landscape, the delicate pink in the cheek of a child, the blush of a
rose, the shimmering green of the lake--these reside not in the objects
themselves, but in the consciousness of the one who sees them. The
objects possess but the quality of reflecting back to the eye ether
waves of the particular rate corresponding to the color which we ascribe
to them. Thus "red" objects, and no others, reflect back ether waves of
a rate of 450 billions a second: "white" objects reflect all rates;
"black" objects reflect none.

The case is no different with regard to sound. When we speak of a sound
coming from a bell, what we really mean is that the vibrations of the
bell have set up waves in the air between it and our ear, which have
produced corresponding vibrations in the ear; that a nerve current was
thereby produced; and that a sound was heard. But the sound (i.e.,
sensation) is a mental thing, and exists only in our own consciousness.
What passed between the sounding object and ourselves was waves in the
intervening air, ready to be translated through the machinery of nerves
and brain into the beautiful tones and melodies and harmonies of the
mind. And so with all other sensations.

THE THREE SETS OF FACTORS.--What exists outside of us therefore is a
_stimulus_, some form of physical energy, of a kind suitable to excite
to activity a certain end-organ of taste, or touch, or smell, or sight,
or hearing; what exists within us is the _nervous machinery_ capable of
converting this stimulus into a nerve current which shall produce an
activity in the cortex of the brain; what results is the _mental object_
which we call a _sensation_ of taste, smell, touch, sight, or hearing.

2. THE NATURE OF SENSATION

SENSATION GIVES US OUR WORLD OF QUALITIES.--In actual experience
sensations are never known apart from the objects to which they belong.
This is to say that when we see _yellow_ or _red_ it is always in
connection with some surface, or object; when we taste _sour_, this
quality belongs to some substance, and so on with all the senses. Yet by
sensation we mean only _the simple qualities of objects known in
consciousness as the result of appropriate stimuli applied to
end-organs_. We shall later see how by perception these qualities fuse
or combine to form objects, but in the present chapter we shall be
concerned with the qualities only. Sensations are, then, the simplest
and most elementary knowledge we may get from the physical world,--the
red, the blue, the bitter, the cold, the fragrant, and whatever other
qualities may belong to the external world. We shall not for the present
be concerned with the objects or sources from which the qualities may
come.

To quote James on the meaning of sensation: "All we can say on this
point is that _what we mean by sensations are first things in the way of
consciousness_. They are the _immediate_ results upon consciousness of
nerve currents as they enter the brain, and before they have awakened
any suggestions or associations with past experience. But it is obvious
that _such immediate sensations can be realized only in the earliest
days of life_."

THE ATTRIBUTES OF SENSATION.--Sensations differ from each other in at
least four respects; namely, _quality_, _intensity_, _extensity_, and
_duration_.

It is a difference in _quality_ that makes us say, "This paper is red,
and that, blue; this liquid is sweet, and that, sour." Differences in
quality are therefore fundamental differences in _kind_. Besides the
quality-differences that exist within the same general field, as of
taste or vision, it is evident that there is a still more fundamental
difference existing between the various fields. One can, for example,
compare red with blue or sweet with sour, and tell which quality he
prefers. But let him try to compare red with sweet, or blue with sour,
and the quality-difference is so profound that there seems to be no
basis for comparison.

Differences in _intensity_ of sensation are familiar to every person who
prefers two lumps of sugar rather than one lump in his coffee; the sweet
is of the same quality in either case, but differs in intensity. In
every field of sensation, the intensity may proceed from the smallest
amount to the greatest amount discernible. In general, the intensity of
the sensation depends on the intensity of the stimulus, though the
condition of the sense-organ as regards fatigue or adaptation to the
stimulus has its effect. It is obvious that a stimulus may be too weak
to produce any sensation; as, for example, a few grains of sugar in a
cup of coffee or a few drops of lemon in a quart of water could not be
detected. It is also true that the intensity of the stimulus may be so
great that an increase in intensity produces no effect on the sensation;
as, for example, the addition of sugar to a solution of saccharine would
not noticeably increase its sweetness. The lowest and highest intensity
points of sensation are called the lower and upper _limen_, or
threshold, respectively.

By _extensity_ is meant the space-differences of sensations. The touch
of the point of a toothpick on the skin has a different space quality
from the touch of the flat end of a pencil. Low tones seem to have more
volume than high tones. Some pains feel sharp and others dull and
diffuse. The warmth felt from spreading the palms of the hands out to
the fire has a "bigness" not felt from heating one solitary finger. The
extensity of a sensation depends on the number of nerve endings
stimulated.

The _duration_ of a sensation refers to the time it lasts. This must not
be confused with the duration of the stimulus, which may be either
longer or shorter than the duration of the sensation. Every sensation
must exist for some space of time, long or short, or it would have no
part in consciousness.

3. SENSORY QUALITIES AND THEIR END-ORGANS

All are familiar with the "five senses" of our elementary physiologies,
sight, hearing, taste, smell, and touch. A more complete study of
sensation reveals nearly three times this number, however. This is to
say that the body is equipped with more than a dozen different kinds of
end-organs, each prepared to receive its own particular type of
stimulus. It must also be understood that some of the end-organs yield
more than one sense. The eye, for example, gives not only visual but
muscular sensations; the ear not only auditory, but tactual; the tongue
not only gustatory, but tactual and cold and warmth sensations.

SIGHT.--Vision is a _distance_ sense; we can see afar off. The stimulus
is _chemical_ in its action; this means that the ether waves, on
striking the retina, cause a chemical change which sets up the nerve
current responsible for the sensation.

The eye, whose general structure is sufficiently described in all
standard physiologies, consists of a visual apparatus designed to bring
the images of objects to a clear focus on the retina at the _fovea_, or
area of clearest vision, near the point of entrance of the optic nerve.

The sensation of sight coming from this retinal image unaided by other
sensations gives us but two qualities, _light and color_. The eye can
distinguish many different grades of light from purest white on through
the various grays to densest black. The range is greater still in color.
We speak of the seven colors of the spectrum, violet, indigo, blue,
green, yellow, orange, and red. But this is not a very serviceable
classification, since the average eye can distinguish about 35,000 color
effects. It is also somewhat bewildering to find that all these colors
seem to be produced from the four fundamental hues, red, green, yellow,
and blue, plus the various tints. These four, combined in varying
proportions and with different degrees of light (i.e., different shades
of gray), yield all the color effects known to the human eye. Herschel
estimates that the workers on the mosaics at Rome must have
distinguished 30,000 different color tones. The _hue_ of a color refers
to its fundamental quality, as red or yellow; the _chroma_, to its
saturation, or the strength of the color; and the _tint,_ to the amount
of brightness (i.e., white) it contains.

HEARING.--Hearing is also a distance sense. The action of its stimulus
is mechanical, which is to say that the vibrations produced in the air
by the sounding body are finally transmitted by the mechanism of the
middle ear to the inner ear. Here the impulse is conveyed through the
liquid of the internal ear to the nerve endings as so many tiny blows,
which produce the nerve current carried to the brain by the auditory
nerve.

The sensation of hearing, like that of sight, gives us two qualities:
namely, _tones_ with their accompanying pitch and timbre, and _noises_.
Tones, or musical sounds, are produced by isochronous or equal-timed
vibrations; thus _C_ of the first octave is produced by 256 vibrations a
second, and if this tone is prolonged the vibration rate will continue
uniformly the same. Noises, on the other hand, are produced by
vibrations which have no uniformity of vibration rate. The ear's
sensibility to pitch extends over about seven octaves. The seven-octave
piano goes down to 27-1/2 vibrations and reaches up to 3,500 vibrations.
Notes of nearly 50,000 vibrations can be heard by an average ear,
however, though these are too painfully shrill to be musical. Taking
into account this upper limit, the range of the ear is about eleven
octaves. The ear, having given us _loudness_ of tones, which depends on
the amplitude of the vibrations, _pitch_, which depends on the rapidity
of the vibrations, and _timbre_, or _quality_, which depends on the
complexity of the vibrations, has no further qualities of sound to
reveal.

TASTE.--The sense of taste is located chiefly in the tongue, over the
surface of which are scattered many minute _taste-bulbs_. These can be
seen as small red specks, most plentifully distributed along the edges
and at the tip of the tongue. The substance tasted must be in
_solution_, and come in contact with the nerve endings. The action of
the stimulus is _chemical_.

The sense of taste recognizes the four qualities of _sour_, _sweet_,
_salt_, and _bitter_. Many of the qualities which we improperly call
tastes are in reality a complex of taste, smell, touch, and temperature.
Smell contributes so largely to the sense of taste that many articles of
food become "tasteless" when we have a catarrh, and many nauseating
doses of medicine can be taken without discomfort if the nose is held.
Probably none of us, if we are careful to exclude all odors by plugging
the nostrils with cotton, can by taste distinguish between scraped
apple, potato, turnip, or beet, or can tell hot milk from tea or coffee
of the same temperature.

SMELL.--In the upper part of the nasal cavity lies a small brownish
patch of mucous membrane. It is here that the olfactory nerve endings
are located. The substance smelled must be volatile, that is, must exist
in gaseous form, and come in direct contact with the nerve endings.
Chemical action results in a nerve current.

The sensations of smell have not been classified so well as those of
taste, and we have no distinct names for them. Neither do we know how
many olfactory qualities the sense of smell is capable of revealing. The
only definite classification of smell qualities is that based on their
pleasantness or the opposite. We also borrow a few terms and speak of
_sweet_ or _fragrant_ odors and _fresh_ or _close_ smells. There is some
evidence when we observe animals, or even primitive men, that the human
race has been evolving greater sensibility to certain odors, while at
the same time there has been a loss of keenness of what we call scent.

VARIOUS SENSATIONS FROM THE SKIN.--The skin, besides being a protective
and excretory organ, affords a lodging-place for the end-organs giving
us our sense of pressure, pain, cold, warmth, tickle, and itch.
_Pressure_ seems to have for its end-organ the _hair-bulbs_ of the skin;
on hairless regions small bulbs called the _corpuscles of Meissner_
serve this purpose. _Pain_ is thought to be mediated by free nerve
endings. _Cold_ depends on end-organs called the _bulbs of Krause_; and
_warmth_ on the _Ruffinian corpuscles_.

Cutaneous or skin sensation may arise from either _mechanical_
stimulation, such as pressure, a blow, or tickling, from _thermal_
stimulation from hot or cold objects, from _electrical_ stimulation, or
from the action of certain _chemicals_, such as acids and the like.
Stimulated mechanically, the skin gives us but two sensation qualities,
_pressure_ and _pain_. Many of the qualities which we commonly ascribe
to the skin sensations are really a complex of cutaneous and muscular
sensations. _Contact_ is light pressure. _Hardness_ and _softness_
depend on the intensity of the pressure. _Roughness_ and _smoothness_
arise from interrupted and continuous pressure, respectively, and
require movement over the rough or smooth surface. _Touch_ depends on
pressure accompanied by the muscular sensations involved in the
movements connected with the act. Pain is clearly a different sensation
from pressure; but any of the cutaneous or muscular sensations may, by
excessive stimulation, be made to pass over into pain. All parts of the
skin are sensitive to pressure and pain; but certain parts, like the
finger tips, and the tip of the tongue, are more highly sensitive than
others. The skin varies also in its sensitivity to _heat_ and _cold_. If
we take a hot or a very cold pencil point and pass it rather lightly and
slowly over the skin, it is easy to discover certain spots from which a
sensation of warmth or of cold flashes out. In this way it is possible
to locate the end-organs of temperature very accurately.

[Illustration: FIG. 17.--Diagram showing distribution of hot and cold
spots on the back of the hand. C, cold spots; H, hot spots.]

THE KINAESTHETIC SENSES.--The muscles, tendons, and joints also give rise
to perfectly definite sensations, but they have not been named as have
the sensations from most of the other end-organs. _Weight_ is the most
clearly marked of these sensations. It is through the sensations
connected with movements of muscles, tendons, and joints that we come to
judge _form_, _size_, and _distance_.

THE ORGANIC SENSES.--Finally, to the sensations mentioned so far must be
added those which come from the internal organs of the body. From the
alimentary canal we get the sensations of _hunger_, _thirst_, and
_nausea_; from the heart, lungs, and organs of sex come numerous
well-defined but unnamed sensations which play an important part in
making up the feeling-tone of our daily lives.

Thus we see that the senses may be looked upon as the sentries of the
body, standing at the outposts where nature and ourselves meet. They
discover the qualities of the various objects with which we come in
contact and hand them over to the mind in the form of sensations. And
these sensations are the raw material out of which we begin to construct
our material environment. Only as we are equipped with good organs of
sense, especially good eyes and ears, therefore, are we able to enter
fully into the wonderful world about us and receive the stimuli
necessary to our thought and action.

4. PROBLEMS IN OBSERVATION AND INTROSPECTION

1. Observe a schoolroom of children at work with the aim of discovering
any that show defects of vision or hearing. What are the symptoms? What
is the effect of inability to hear or see well upon interest and
attention?

2. Talk with your teacher about testing the eyes and ears of the
children of some school. The simpler tests for vision and hearing are
easily applied, and the expense for material almost nothing. What tests
should be used? Does your school have the test card for vision?

3. Use a rotator or color tops for mixing discs of white and black to
produce different shades of gray. Fix in mind the gray made of half
white and half black; three-fourths white and one-fourth black;
one-fourth-white and three-fourths black.

4. In the same way mix the two complementaries yellow and blue to
produce a gray; mix red and green in the same way. Try various
combinations of the four fundamental colors, and discover how different
colors are produced. Seek for these same colors in nature--sky, leaves,
flowers, etc.

5. Take a large wire nail and push it through a cork so that it can be
handled without touching the metal with the fingers. Now cool it in ice
or very cold water, then dry it and move the point slowly across the
back of the hand. Do you feel occasional thrills of cold as the point
passes over a bulb of Krause? Heat the nail with a match flame or over a
lamp, and perform the same experiment. Do you feel the thrills of heat
from the corpuscles of Ruffini?

6. Try stopping the nostrils with cotton and having someone give you
scraped apple, potato, onion, etc., and see whether, by taste alone, you
can distinguish the difference. Why cannot sulphur be tasted?

CHAPTER VII

PERCEPTION

No young child at first sees objects as we see them, or hears sounds as
we hear them. This power, the power of perception, is a gradual
development. It grows day by day out of the learner's experience in his
world of sights and sounds, and whatever other fields his senses respond
to.

1. THE FUNCTION OF PERCEPTION

NEED OF KNOWING THE MATERIAL WORLD.--It is the business of perception to
give us knowledge of our world of material _objects_ and their relations
in _space_ and _time_. The material world which we enter through the
gateways of the senses is more marvelous by far than any fairy world
created by the fancy of story-tellers; for it contains the elements of
all they have conceived and much more besides. It is more marvelous than
any structure planned and executed by the mind of man; for all the
wonders and beauties of the Coliseum or of St. Peter's existed in nature
before they were discovered by the architect and thrown together in
those magnificent structures. The material advancement of civilization
has been but the discovery of the objects, forces, and laws of nature,
and their use in inventions serviceable to men. And these forces and
laws of nature were discovered only as they were made manifest through
objects in the material world.

The problem lying before each individual who would enter fully into this
rich world of environment, then, is to discover at first hand just as
large a part of the material world about him as possible. In the most
humble environment of the most uneventful life is to be found the
material for discoveries and inventions yet undreamed of. Lying in the
shade of an apple tree under the open sky, Newton read from a falling
apple the fundamental principles of the law of gravitation which has
revolutionized science; sitting at a humble tea table Watt watched the
gurgling of the steam escaping from the kettle, and evolved the steam
engine therefrom; with his simple kite, Franklin drew down the lightning
from the clouds, and started the science of electricity; through
studying a ball, the ancient scholars conceived the earth to be a
sphere, and Columbus discovered America.

THE PROBLEM WHICH CONFRONTS THE CHILD.--Well it is that the child,
starting his life's journey, cannot see the magnitude of the task before
him. Cast amid a world of objects of whose very existence he is
ignorant, and whose meaning and uses have to be learned by slow and
often painful experience, he proceeds step by step through the senses in
his discovery of the objects about him. Yet, considered again, we
ourselves are after all but a step in advance of the child. Though we
are somewhat more familiar with the use of our senses than he, and know
a few more objects about us, yet the knowledge of the wisest of us is at
best pitifully meager compared with the richness of nature. So
impossible is it for us to know all our material environment, that men
have taken to becoming specialists. One man will spend his life in the
study of a certain variety of plants, while there are hundreds of
thousands of varieties all about him; another will study a particular
kind of animal life, perhaps too minute to be seen with the naked eye,
while the world is teeming with animal forms which he has not time in
his short day of life to stop to examine; another will study the land
forms and read the earth's history from the rocks and geological strata,
but here again nature's volume is so large that he has time to read but
a small fraction of the whole. Another studies the human body and learns
to read from its expressions the signs of health and sickness, and to
prescribe remedies for its ills; but in this field also he has found it
necessary to divide the work, and so we have specialists for almost
every organ of the body.

2. THE NATURE OF PERCEPTION

HOW A PERCEPT IS FORMED.--How, then, do we proceed to the discovery of
this world of objects? Let us watch the child and learn the secret from
him. Give the babe a ball, and he applies every sense to it to discover
its qualities. He stares at it, he takes it in his hands and turns it
over and around, he lifts it, he strokes it, he punches it and jabs it,
he puts it to his mouth and bites it, he drops it, he throws it and
creeps after it. He leaves no stone unturned to find out what that thing
really is. By means of the _qualities_ which come to him through the
avenues of sense, he constructs the _object_. And not only does he come
to know the ball as a material object, but he comes to know also its
uses. He is forming his own best definition of a ball in terms of the
sensations which he gets from it and the uses to which he puts it, and
all this even before he can name it or is able to recognize its name
when he hears it. How much better his method than the one he will have
to follow a little later when he goes to school and learns that "A ball
is a spherical body of any substance or size, used to play with, as by
throwing, kicking, or knocking, etc.!"

THE PERCEPT INVOLVES ALL RELATIONS OF THE OBJECT.--Nor is the case in
the least different with ourselves. When we wish to learn about a new
object or discover new facts about an old one, we do precisely as the
child does if we are wise. We apply to it every sense to which it will
afford a stimulus, and finally arrive at the object through its various
qualities. And just in so far as we have failed to use in connection
with it every sense to which it can minister, just in that degree will
we have an incomplete perception of it. Indeed, just so far as we have
failed finally to perceive it in terms of its functions or uses, in that
far also have we failed to know it completely. Tomatoes were for many
years grown as ornamental garden plants before it was discovered that
the tomatoes could minister to the taste as well as to the sight. The
clothing of civilized man gives the same sensation of texture and color
to the savage that it does to its owner, but he is so far from
perceiving it in the same way that he packs it away and continues to go
naked. The Orientals, who disdain the use of chairs and prefer to sit
cross-legged on the floor, can never perceive a chair just as we do who
use chairs daily, and to whom chairs are so saturated with social
suggestions and associations.

THE CONTENT OF THE PERCEPT.--The percept, then, always contains a basis
of _sensation_. The eye, the ear, the skin or some other sense organ
must turn in its supply of sensory material or there can be no percept.
But the percept contains more than just sensations. Consider, for
example, your percept of an automobile flashing past your windows. You
really _see_ but very little of it, yet you _perceive_ it as a very
familiar vehicle. All that your sense organs furnish is a more or less
blurred patch of black of certain size and contour, one or more objects
of somewhat different color whom you know to be passengers, and various
sounds of a whizzing, chugging or roaring nature. Your former experience
with automobiles enables you to associate with these meager sensory
details the upholstered seats, the whirling wheels, the swaying movement
and whatever else belongs to the full meaning of a motor car.

The percept that contained only sensory material, and lacked all memory
elements, ideas and meanings, would be no percept at all. And this is
the reason why a young child cannot see or hear like ourselves. It lacks
the associative material to give significance and meaning to the sensory
elements supplied by the end-organs. The dependence of the percept on
material from past experience is also illustrated in the common
statement that what one gets from an art exhibit or a concert depends on
what he brings to it. He who brings no knowledge, no memory, no images
from other pictures or music will secure but relatively barren percepts,
consisting of little besides the mere sensory elements. Truly, "to him
that hath shall be given" in the realm of perception.

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