Introduction to psychology

Introduction To

PSYCHOLOGY.

COPYRIGHT DEPOSIT.

INTRODUCTION TO

PSYCHOLOGY

BY GEO. W. NEET,

Professor of Pedagogy in Valparaiso University, Valparaiso, Indiana.

Putliskcr,

Valparaiso, Indiana,

1906,

LIBRARY »f CONGRESS

Two Copies Keceivcd

C«»yrirht Entry

CO^Y B.

Preface

These studies in psychology are intended primarily for use in the author's own classes. As the title implies they are merely introductory to psychology. Every teacher of psychology has doubtless felt the need of work in his classes of which the definition of terms constitutes a large part. Such work is necessary preparation for intensive psychological study further on. It is the intention to supply this need in the author's own classes, that prompts to the present little volume.

A second thought is to give students a general idea of the organization of psychology, and a comprehension of its organizing principle to the end that an intensive study of any particular aspect of the subject may be seen in its proper relation to the science as a whole.

G. W. N.

Chapter I. The Nature, Subject-matter And Method Of Psychology

The Meaning of Science. — Every one who has lived very long among people has some knowledge of the human mind. This knowledge he has picked up here and there by experience. An examination of this knowledge will show that it is in bits, scraps, and fragments; that it consists of truth mixed with error; that is. it is not very accurate ; and that it is not very extensive, and so not complete. Such knowledge, unsystematic, inaccurate, and incomplete is called common, or ordinary, knowledge. Common knowledge may be transformed by experiment, observation, and thinking into knowledge which is systematic, accurate and complete; that is, into scientific knowledge, or science. Thus the following statement may be made for science :

Science is knowledge which results from making systematic, accurate, and complete commo7i knowledge. It is to be noticed that science is a product of the human mind. It is a mistake to think that, for instance, botany as a science has existed as long as the truths of plant life. Botany has existed only since humanity has learned the truths of plant life, has made them into a system, accurate, and complete. Thus the truths of plant life are many, many years older than botany.

The Presupposition of Science. — Science is based upon the presupposition that the human mind acts uniformly; that is, that under the same conditions, one person's mind acts in general as other persons' minds act; also, that one person's mind acts at one time in general as it acts at other times under the same conditions.

Illustration. — When ten persons look at snow it appears white to each one; also, if one person looks at snow at ten different times, it looks white to him each time. That is to say, the mind acts uniformly, and only this enables it to establish the scientific truth that snow is white. If to one it appeared white; to a second, green; to a third, yellow, and so on, or to one at one time, white; a second time, green; a third time, yellow, and so on, the truth could never be established. And this because the mind did not act uniformly.

Mental Fhenomena. — If one will turn his attention inward and notice what his own mind does, one of the first things which he will discover is that it changes. Now he finds his mind thinking, for instance, about grammar and at another time he finds his mind thinking about history. The only way he can account for his mind's heing in different conditions at different times is that it changes. This, one knows, if he knows anything. There is nothing of which one can be more certain than that his mind changes. These changes of the mind psychologists call mental phenomena. A change is a phenomenon, and a mental change is a mental phenomenon. Other terms which have the same

Introduction To Psychology. 9

meaning are activity and experience. From the above the following statement may be made :

A mental phenomenon is a mental change, or activity, of any kind.

Physical Phenomena. — Any physical thing is a thing which occupies space, such as wood, a book, a horse, or one's body. If one observes physical things about his first discovery is, that they change. This he knows as well as he can know anything except that his mind changes. That his mind changes he knows most surely of all things.

The thing that enables one to know that physical things change is that they are found to be in different conditions and positions at different times, and the only explanation for this is that they have changed.

The human body occupies space, and since it is seen to be in different conditions and different positions at different times, it is known to change. These changes of the body are physical phenomena.

An important truth about mental phenomena is that all mental phenomena are accompanied by physical phenomena. Sometimes the physical phenomena seem to precede the mental, and sometimes the mental seem to precede the physical, and sometimes they seem to be simultaneous. But in any case, so far as we know, there is never a mental phenomenon unless there is in some way connected with it a physical phenomenon. They are said to correspond; that is, there are corresponding mental and physical phenomena.

Now, no one knows ultimately what the mind is, nor can any one study the mind directly. But no one lO INTRODUCTION TO PSYCHOLOGY.

knows ultimately what a tree is ; no one knows what light or electricity is. We do know, though, how they act or change; that is, we know their phenomena, and such knowledge is very valuable to us. So we need not be discouraged that we can not know or study the mind directly, for we can know and study its phenomena and that is as much as we can study and know about anything. Now the science which deals with the phenomena of the mind and the corresponding phenomena of some part or parts of the body is psychology.

Every science deals with laws ; that is, truths which are true of a large number of cases. Thus, psychology deals with the laws of mental and corresponding physical phenomena, truths that are true of the phenomena of all normal minds. From the above study the following definition of psychology is reached :

Psychology is the science which treats of the laws of mental phenomena together with their corresponding physical phenomena.

The word, psychology, is derived from the two Greek words, psyche, meaning mind or soul and logos, meaning thought or knowledge.. Thus literally psychology means knowledge of soul or mind.

The terms mind, soul, and spirit are used interchangeably by psychologists. Theology makes some distinctions in the meanings of these terms, but such distinctions are not observed in psychology.

Subject-matter of Psychology, — In the mastery of any subject various points of truth must be studied and learned. These truths are usually called facts. Also in mastering the subject the connection among the facts or

Introduction To Psychology. 11

truths of the subject must be learned. Thus in mastering a subject the facts and their relations must be learned. These facts and relations in any subject constitute its subject-matter. The following are formal statements for subject-matter :

A subject-matter of any subject is the facts and relations to be learned in any subject.

A subject-matter is the material of study in any subject.

In the subject-matter of psychology are to be found two points in general, as follows :

1. Mental phenomena.

2. Corresponding physical phenomena.

In physiology physical phenomena are studied, too. But physiology is not psychology. Not so many physical phenomena are studied in psychology as are studied in physiology. For instance, circulation, respiration, and digestion are studied carefuUy in physiology, but are hardly studied at aU in psychology.

And again the physical phenomena are studied in psychology in different connections, or relations, from what they are studied in physiology. In psychology they are always studied in connection with the mental phenomena, in so far as they affect and in turn are affected by mental phenomena.

The Method of Psychology. — The question for study in this connection is In what manner may the mind study psychology 'f That is to say. How may the mind get at, classify, and explain the facts of psychology?

In general the four following methods of studying psychology may be seen :

1. The Introspective method.

2. The Experimental method.

3. The Comparative method.

4. The Objective method.

Introspective Method. — The introspective method is the process of studying psychology by means of introspection. But what is introspection? It comes from intro meaning within and spicere, meaning to look. The ion in the word signifies the act of. Thus introspection is the act of looking within.

We learn the physical phenomena in the world around us with our senses; with sight, hearing, touch, taste, etc. Thus we learn the moving of objects, lightning, thunder, the fragrance of the rose, and the aroma of fruit. But we cannot learn the phenomena of the mind in this way. These must be learned by the mind's looking into itself. We can turn our minds in upon themselves and let them learn their own phenomena. Thus we can study our wishes, our hopes, our motives, our thoughts, and our feelings. The process of thus looking within with the mind's eye is introspection. The following is a formal statement for it:

Introspection is the process of making one^s own mental phenomena ohjects of study to find out what they are.

Introspection is also called internal perception.

Difficulty of Introspection. — There are two aspects to the difficulty of introspection.

1. It is hard for those who have been used to studying objects learned through the senses to turn their

Introduction To Psychology. 13

minds in upon intangible, spiritual things and study them.

2. If one turns his mind in upon a thought or feeling to study it, it at once disappears and he has only the memory of it to study.

The things in our minds which we know through introspection are objects just as truly as the things we touch, taste, see, etc. But so accustomed do we become to thinking of only the things which we can know through senses as objects that it is difficult at first for us to see that mental phenomena are also objects. Thus since it is difficult to think of mental phenomena at all, it is of course much more difficult to observe, explain, and classify them accurately.

It is one thing to have the feeling of love or anger but an entirely different thing to study it. Just as soon as the mind is turned inward to study the love or anger, it disappears and only the memory of it remains to be examined.

But even if the introspective method does have its two difficulties, it is entirely necessary to the study of psychology. Without introspection no one could ever be made to understand mental phenomena. No one can understand anger except he himself has been angry, and he can study his own anger only through the introspective method.

Psychology must then he studied hy the introspective method.

The Experimental Method. — We can experiment with plants directly in the study of botany ; with animals directly in the study of zoology, or with matter directly in the study of physics, but not with mental phenomena directly in studying psychology. Yet there is such a thing as the experimental method in studying psychology. We can experiment with the mind indirectly through its connection with the body. The connections of the mind with the body; that is, its connection with eyes, ears, nerves, muscles, etc., can be experimented with, and thus mental phenomena changed and studied.

The study of mental phenomena in connection with the body gives rise to what is called physiological psychology ; that is, the study of physiology in connection with mental phenomena not for the purpose of better understanding the physiology, but for the purpose of better understanding the psychology.

The study of mental phenomena wholly through introspection gives rise to introspective psychology ; that is, psychology so far as it can be learned through introspection.

Comparative Method. — Psychology deals essentially with the phenomena of the normal mind. But help comes to the student of psychology from comparing the phenomena of the normal mind with phenomena of other minds. Thus the phenomena of the normal adult mind may be compared with the phenomena of the minds of the following:

1. Lower animals.

2. Children in various stages of development.

3. Persons with defective or disordered minds. The study of psychology through such comparing

is by the comparative method, and gives rise to what is called comparative psychology.

Introduction To Psychology. 15

The Objective Method. — The mind acts and produces results which are objective. The student can study these objective results of the mind and thus learn much about it in a similar way to his learning much about electricity by studying the results it produces. These objective results are fixed, certain and definite signs to us of the way the mind works. Some of these results are :

1. Language and science.

2. Institutions of civilization.

3. Artistic creations.

4. Philosophy and religion.

Studying mental phenomena by means of these objective manifestations is by the objective method.

Necessity of Introspection. — It matters not by what method we study mental phenomena we are able to understand them only by referring them to our own mental experiences and this we can do only by introspection. Thus the student of psychology can make no progress at all in its study without introspection. No one who had never had a sensation could be made to understand what a sensation is. The man who had always been blind thought scarlet must resemble the sound of a trumpet.

Thus the introspective method in psychology is the most fundamental method, and introspective psychology is the most fundamental kind of psychology.

The Nature of the Mind. — The question always asked the psychological student either by himself or by some one else and never very satisfactorily answered is What is the mindl This question is no more unanswerable than the questions, What is electricity? or What is matter ?

Every student soon learns that the most persistent thing in the world in which he lives is force; that is, that which does work. Force does all the work done in the world of any kind whatever. Force working in various forms which we can in any way know we call various things. Thus force manifests itself in one way and we call it electricity ; in another way and we call it heat ; in another way and we call it gravitation; in another way and we call it a horse ; in another way and we call it an oak tree ; in another way and we call it a star ; in another way and we call it the mind. But the form in which the force which we call the mind manifests itself is in consciousness. Thus the following definition of the mind is reached :

The mind is that form of force which manifests itself in the phenomena of consciousness.

It is not supposed that this definition will be fully comprehended by the student who is a beginner in psychology, but it is believed that further study will clarify and elaborate it to such an extent that it will prove very helpful.

Chapter II. The Units Op Investigation

Meaning of Unit of Investigation. — The subject of psychology is a science, and has resulted from the fact that the human mind is dissatisfied with common, or ordinary, knowledge and abhors vagueness. In its effort to change ordinary knowledge to science it begins by stripping away from the subject of study all irrelevant, accidental, and occasional facts, seeking the simple, elementary, and persistent. It is this simplest, most elementary, and persistent form of the subject-matter which is the unit of investigation. The formal statement for it is as follows :

The unit of investigation in any science is the simplest, most elementary, and persistent form of its subject-matter. That is to say, it is the simplest, most elementary, and persistent whole thing which can be studied in a science.

Each science has its unit of investigation. The chemist knows that his science is concerned with the element; namely, oxygen, hydrogen, carbon, calcium, sodium, chlorine, nitrogen, etc. He studies their number, qualities, atomic weights, combinations and products. Thus the element is the unit of investigation in chemistry.

The botanists have found that their unit of investigation is the organic vegetable cell. The zoologists have found that their unit of investigation is the organic animal cell. They study its structure, development, combinations and products.

The science of psychology differs somewhat from other sciences with regard to its unit of investigation. Other sciences have but one unit, psychology has two. This is because of the two distinct divisions in the subject-matter of psychology: first, the mental phe7iomena, and secondly, the corresponding physical phenomena. The unit of investigation in the study of the physical phenomena is the nerve cell. The unit of investigation in the study of the mental phenomena is the sensation.

Hotv It May Be Studied. — How does the psychologist study the unit of investigation in psychology 1

His first task is to observe it in order to find out what it is; that is, its nature so that he may be able to think about it in some definite way.

His second task is to find out how it behaves itself; how it acts ; what its processes are under various conditions.

His third task is to find out what new products or combinations are brought into being as a result of the activities or processes of the unit of investigation.

The psychologist 's fourth task is to discover, formulate, state and learn the laws and principles of both the mental phenomena and the corresponding physical phenomena.

The Nerve Cell. — The nerve cell is a small body of neucleated nervous matter with thread-like extensions

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reaching from it. Both the central body and the thread-like extensions make up the nerve cell. The extensions are of the same kind of material as the central body and are continuous with it. It has been sometimes stated that just the central body is the nerve cell. And that the extensions from it are not portions of the cell. But this is wrong. It takes both the central body and all the extensions to make the nerve cell. Nerve cells thus consisting of the central body and the extensions are called neurones by neurologists.

Form of Neurones. — Neurones are of various forms. The central body may be spherical, cylindricaly pyramidal or irregular. All are however more or less irregular and all developed cells have the thread-like extensions. There are mere germ cells which have no extensions. They are, so to speak, undeveloped baby cells. They are called neuroblasts.

Material of Nerve Cells. — Nerve cells are composed of a granular, viscid substance usually called protoplasm. Protoplasm is a living substance. Vitality is one of its necessary characteristics. There is no such thing as dead protoplasm. Its exact chemical composition is unknown, though it is known to be very complex. Its main characteristics are absorption, secretion and excretion.

Nerve Fibers. — Nerve fibers are parts of nerve cells, the extensions, or prolongations, leading off from the central body. They are too small to be seen with the naked eye, but vary much in both diameter and length. Some are as large as one twelve hundredth of an inch in diameter, and some are no larger than one one hundred thousandth of an inch in diameter. They vary in size between these two extremes. They have a branching structure and vary in length from a part of an inch to several feet in length.

There are in general two kinds of nerve fibers: those which carry impulses toward nerve centers, and those which carry impulses from nerve centers. Those of the first kind are called afferent nerve fibers and those of the second kind, efferent nerve fibers. The derivation of these words helps in remembering their meaning. Afl'erent is from ad, meaning to and ferre, to carry. Thus afferent nerve fibers are carrying to nerve fibers. Efferent is from ex, meaning from and ferre, to carry. Thus efferent nerve fibers are carrying from nerve fibers.

Sensory and motor are terms which mean nearly the same as afferent and efferent when applied to nerve fibers, but not quite the same. Sensory and motor are not quite as broad terms as afferent and efferent. Nerve fibers that carry impulses to nerve centers which do not result in consciousness are afferent nerve fibers, but not sensory. Such are the afferent nerve fibers carrying impulses from the iris of the eye to their nerve centers. And nerve fibers carrying impulses from their nerve centers which do not result in muscular action are efferent nerve fibers, but not motor. Such are the fibers carrying impulses from their centers to the liver, resulting in the secretion of the bile.

The function of the nerve fibers is to unify the action of the nervous system. This they do by carrying impulses from one nerve center to another. Thus by

Introduction To Psychology. 21

means of the nerve fibers the touch corpuscles in one's toes are in communication with the nerve centers in the highest part of one's brain.

Number of Nerve Cells. — The number of nerve cells in the human body is so great that one can form no adequate idea of them. It is estimated that there are more than three thousand million in the brain alone. At any rate it is certain that every one has a good many million which remain unused and so never develop.

It is well known that cells increase in number by cell division. Nerve cells increase in number in this way early in the life of the human being. But this increase in the number of nerve cells in the human being ceases before birth. There is no increase in the number of nerve cells in the human body after birth. Not one of us has a nerve cell more than we had when we were born. Some of us may have fewer, but none has more.

Connectioyis Among Nerve Cells, — Contrary to popular belief, no two nerve cells in the human body have a continuous nervous connection. Each nerve cell is a distinct and separate thing. There is no extension from any nerve cell which is continuous with the extension from any other nerve cell. Thus there is not a connection of continuity between nerve cells.

How then are nerve cells connected ? Very much in the same way that the branches of two trees growing side by side are connected. Or in the same w^ay that the roots of two trees growing side by side are connected. This connection is a connection of contact. Thus nerve cells have contact connections but do not have connections of continuity.

It has previously been seen that developed nerve cells consist partly of extensions or prolongations from the central body.

''These are of two kinds, (1) the axone, a fiber having the quality of conductivity and becoming what we have called the axis cylinder of a simple nerve, or nerve fiber; (2) the dendrons, which divide into finer branches or rootlets, called dendrites. Their functions are somewhat uncertain, including possibly that of nutrition in the service of the cell body, but probably that of conductivity also.

'^Axones. — The axones have a branching structure and vary greatly in length, from a fraction of an inch up to two or three feet, according to location and use. They often branch greatly, throwing off side branches called laterals, which branch again in turn. They usually terminate in little tufts resembling the fingers of a hand, or the rootlets of a plant, and known as the arborization of the axone. The arborization of one axone may, in appearance, clasp or encompass the cell body of another neurone, or the arborization of one axone may, interlace with the dendrites of another, and thus effect communication with it by a process thought to be similar to that of electrical induction. The arborized connections between neurones are numerous in the spinal cord and medulla, and seem to obviate the necessity for axones of greater length, while furnishing a greater diversity of paths between various parts of the brain and the outlying members of the body. Neurones are anatomically separate, do not penetrate one another, but

Introduction To Psychology. 23

communicate force something like a row of men clasping hands with one another."

The Sensation. — When the end of any sensorynerve fiber is stimulated, it arouses a disturbance there; this disturbance extends along the nerve fibers until it reaches the brain and causes a disturbance there which in some way arouses a state of consciousness, if the disturbance is great enough. This state of consciousness is what psychologists call the sensation. The awareness of cold, warmth, pressure, color, noise are states of consciousness which are sensations.

Steps Leading to. — The steps leading to the sensation are partly mental and partly physical, and are as follows :

1. External stimulus.

2. Excitation of outer nerve ending.

3. Transmission of impulse.

4. Disturbance in brain.

5. Corresponding disturbance in mind.

6. The resulting state of consciousness — the sensation.

Illustration. If one should put his hand on a hot stove, the motion in the particles of the stove — the stimulus — would cause a disturbance in the touch corpuscles in his hand which would extend along the nerve fibers and arouse a disturbance in the brain. Then there would be a corresponding disturbance in the mind from which would result the pain, the state of consciousness — the sensation.

Or again, if a gun were fired the motion in the air would disturb the ends of the nerve fibers in the ears.

which disturbance would extend along the nerve fibers and disturb the brain. Then there would be a corresponding disturbance in the mind from which would result the sound, the state of consciousness — the sensation.

External Stimulus. — In the two illustrations above the thing which disturbs the outer end of the nerve fibers is motion. In the first instance it is motion in the particles of the stove and in the second it is motion in air. A careful analysis of various kinds of stimulus will reveal the truth that it is always motion in some form.

"But numerous as seem the various ways in which external bodies may affect us it is found that these various modes are reducible to one — motion. Whether a body is near or far, the only way in which it affects the organism so as to occasion sensation is through motion. The motion may be of the whole mass, as when something hits us ; it may be in the inner particles of the thing, as when we taste or smell it ; it may be a movement originated by the body and propagated to us through the vibrations of a medium, as when we hear or see. But some form of motion there must be. An absolutely motionless body would not give rise to any affection of the body such as ultimately results in sensation. ' '

But there may be much motion in the world about us that is not stimulus to us. That motion may be stimulus it must come in contact with some part of the nervous system. Thus the following statement for stimulus is reached :

Stimulus is any form of ^notion which comes in co7ttact with the nervous system.

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While stimulus is most frequently external to the body, it is not necessarily so. But it is always external to the mind.

Excitation of Outer Nerve Ending. — Most of the sensory nerves have specialized outer, or peripheral, endings. The retina of the eye; the touch corpuscles, the taste buds, etc. are the specialized ends of nerve fibers. Motion coming in contact with these arouses them to a state of motion, disturbance, or vibration. It is this disturbance which is called the excitation of th^ peripheral nerve ending.

This disturbance gives the impulse a strong initiative and sends it forward with greater strength than it would otherwise have.

Transmission of Impulse. — The disturbance in the peripheral nerve ending extends along the nerve fiber to the nerve center, the brain, and this is called the transmission of the impulse.

But what is the thing which is called an impulse? It is an excess of energy, or a surplus of force. A surplus of force always produces motion. Thus the impulse produces motion. The nerve fiber may be thought of as made up of very small particles in contact with each other. Stimulus disturbs the end particles which disturb those in contact with them, those disturbing the next, and so on. The motion of each particle is produced by the excess of energy transferred to it by motion. In a similar way a nerve center may possess an excess of energy, or force, and motion results. All motion in the world is the result of impulse, or of an excess of force, or energy. The ultimate source of all impulses in so far as our material universe is concerned is the sun.

Rate of Transmission. — It used to be thought that the impulse was an electrical current passing along the nerve fiber as if it were a wire. But now, since the rate of the nervous impulse has been measured, it is known to be much too slow. The nervous impulse travels about 110 feet per second, while an electric current travels about 186,000 miles per second. One hundred and ten feet per second is the approximate rate of nervous transmission of impulse. Conditions sometimes change this a few feet one way or the other. One hundred and ten feet per second is seventy-five miles per hour. So nervous impulse travels as fast as a train with a speed of seventy-five miles per hour.