CHAPTER I

PSYCHOLOGY

AN ELEMENTARY TEXT-BOOK

BY

HERMANN EBBINGHAUS

PROFESSOR OF PHILOSOPHY IN THE UNIVERSITY OF HALLE; AUTHOR OF

“ÜBER DAS GEDÄCHTNIS,” “GRUNDZÜGE DER PSYCHOLOGIE,” ETC.;

EDITOR OF THE “ZEITSCHRIFT FÜR PSYCHOLOGIE”

TRANSLATED AND EDITED BY

MAX MEYER

PROFESSOR OF EXPERIMENTAL PSYCHOLOGY

IN THE UNIVERSITY OF MISSOURI

BOSTON, U.S.A.

D. C. HEATH & CO., PUBLISHERS

1908

COPYRIGHT, 1908,

BY D. C. HEATH & CO.

TRANSLATOR’S PREFACE

The present book is a free translation of Ebbinghaus’s “Abriss der

Psychologie” (Veit & Co., Leipzig, 1908). It is intended primarily to

serve as a text-book for college students, but it should appeal also to

the general reader. It will commend itself through its brevity and the

excellent proportions of the material selected. The translator became

interested in this book because of the fact that the author has

succeeded in keeping entirely free of all fads, and has presented only

that which is generally accepted by psychological science; on the other

hand, he has given to the highest constructive processes of the human

mind, religion, art, and morality, the attention which they deserve

because of their tremendous importance for human life.

In some places the original text has been somewhat condensed,

particularly in the description of the anatomy of the nervous system in

section 2. Section 4 of the original has been omitted, since its

contents seemed to be sufficiently emphasized in the other sections of

the book. The numbers of the following sections differ, therefore, from

those of the German text. The translator regards this as insignificant,

since his intention is not to aid his brother-psychologists in making

themselves acquainted with Ebbinghaus’s views,--for this end they are

referred to the German original,--but to furnish an elementary text-book

for the English-speaking student. Wherever there was any doubt as to the

comprehensibility to the American student of any application or

illustration of the laws discussed by the author, the translator has

unhesitatingly sacrificed the interest of the professional psychologist

to that of the beginner-student. In a few places he has made slight

additions to the original; for instance, figures 7, 8, and 9 are his own

property. But he has decided to abstain from enumerating all changes,

since this would be of interest only to the professional psychologist.

In no case are his additions opposed to the author’s views.

The questions added to each section are not exercises to be worked out

by the student or puzzles to be solved by the general reader. They are

intended to serve as an aid to the intelligent perusal of the book, by

directing the reader’s attention to the essential contents of each

section.

M. M.

CONTENTS

INTRODUCTION

PAGE

A SKETCH OF THE HISTORY OF PSYCHOLOGY 3

CHAPTER I

GENERAL PSYCHOLOGY

§ 1. BRAIN AND MIND 27

§ 2. THE NERVOUS SYSTEM 30

1. The Elements of the Nervous System 30

2. The Architecture of the Nervous System 34

3. The Anatomy of the Nervous System 38

4. The Nervous System and Consciousness 41

§ 3. EXPLANATION OF THE FUNCTIONAL RELATION BETWEEN

BRAIN AND MIND 43

1. The Brain a Tool of the Mind 44

2. The Brain an Objectified Conception of the Mind 47

CHAPTER II

THE SPECIAL FACTS OF CONSCIOUSNESS

_A._ _The Elements of Mental Life_

§ 4. SENSATION 50

1. The Newly Discovered Kinds of Sensation 50

2. The Other Sensations 57

3. Temporal and Spatial Attributes 65

4. Sensation and Stimulus 69

§ 5. IMAGINATION 78

§ 6. FEELING 81

§ 7. WILLING 85

_B._ _The Fundamental Laws of Mental Life_

§ 8. ATTENTION 87

§ 9. MEMORY 93

§ 10. PRACTICE 99

§ 11. FATIGUE 102

_C._ _The Expressions of Mental Life_

§ 12. PERCEPTION AND MOVEMENT 105

§ 13. THOUGHT AND MOVEMENT 108

CHAPTER III

COMPLICATIONS OF MENTAL LIFE

_A._ _The Intellect_

§ 14. PERCEPTION 114

1. Characteristics of Perception 114

2. Illusions 120

§ 15. IDEATION 123

§ 16. LANGUAGE 128

1. Word Imagery 128

2. The Acquisition of Speech 130

3. The Growth of Language 135

4. The Significance of Language 139

§ 17. JUDGMENT AND REASON 142

1. Coherent Thought 142

2. The Self and the World 145

3. Intelligence 148

§ 18. BELIEF 152

_B._ _Affection and Conduct_

§ 19. COMPLICATIONS OF FEELING 162

1. Feeling Dependent on Form and Content 162

2. Feeling Dependent on Association of Ideas 164

3. Irradiation of Feeling 167

§ 20. EMOTIONS 168

§ 21. COMPLICATIONS OF WILLING 173

§ 22. FREEDOM OF CONDUCT 176

CHAPTER IV

HIGHEST ACCOMPLISHMENTS OF CONSCIOUSNESS

§ 23. EVILS OF KNOWLEDGE 183

§ 24. RELIGION 189

§ 25. ART 196

§ 26. MORALITY 204

CONCLUSION 210

INDEX 213

ILLUSTRATIONS

PAGE

Multipolar Cell Body 30

Pyramidal Cell Body 31

Dendrites of a Nerve Cell of the Cerebellum 31

Various Types of Cell Bodies 32

Longitudinal Section of a Nerve Fiber with Stained Fibrils 32

Terminal Arborization of Optical Nerve Fibers 33

Diagram of Nervous Architecture: Reflex Arches connected by a

Low Nerve Center 36

Diagram of Nervous Architecture: Lower Nerve Centers connected

by a Higher Center 36

Diagram of Nervous Architecture: Higher Nerve Centers connected

by a Still Higher Center 37

Frontal Section of the Right Cerebral Hemisphere 39

Sections of the Cerebral Cortex 40

Localization of Peripheral Functions in the Cerebral Cortex 41

Color Pyramid 59

“A Burnt Child fears the Fire” 111

Two Possibilities of Perception 120

Varieties of Perception 121

Visual and Kinesthetic Control of Voluntary Action: the Former

Intact, the Latter Lost 175

PSYCHOLOGY

AN ELEMENTARY TEXT-BOOK

PSYCHOLOGY

INTRODUCTION

A SKETCH OF THE HISTORY OF PSYCHOLOGY

Psychology has a long past, yet its real history is short. For thousands

of years it has existed and has been growing older; but in the earlier

part of this period it cannot boast of any continuous progress toward a

riper and richer development. In the fourth century before our era that

giant thinker, Aristotle, built it up into an edifice comparing very

favorably with any other science of that time. But this edifice stood

without undergoing any noteworthy changes or extensions, well into the

eighteenth or even the nineteenth century. Only in recent times do we

find an advance, at first slow but later increasing in rapidity, in the

development of psychology.

The general causes which checked the progress of this science and thus

made it fall behind the others can readily be stated:--

“The boundaries of the Soul you cannot find, though you pace off all its

streets, so deep a foundation has it,” runs a sentence of Heraclitus,

and it hits the truth more fully than its author could ever have

expected. The structures and functions of our mental life present the

greatest difficulties to scientific investigation, greater even than

those presented by the phenomena, in many respects similar, of the

bodily life of the higher organisms. These structures and processes

change so unceasingly, are so fleeting, so enormously complex, and

dependent on so many factors hidden yet undoubtedly influential, that it

is difficult even to seize upon them and describe their true substance,

still more difficult to gain an insight into their causal connections

and to understand their significance. We are just now beginning to

recognize the full force of these difficulties. Wherever in recent years

research in any of the many branches of psychology has made any

considerable advance,--as in vision, audition, memory, judgment,--the

first conclusion reached by all investigators has been, that matters are

incomparably finer and richer and fuller of meaning than even a keen

fancy would previously have been able to imagine.

There is, besides, a second obstacle. However difficult it may be to

investigate the nature and causal connections of mental phenomena,

everybody has a superficial knowledge of their external manifestations.

Long before these phenomena were considered scientifically, it was

necessary for practical human intercourse and for the understanding of

human character, that language should give names to the most important

mental complexes occurring in the various situations of daily life, such

as judgment, attention, imagination, passion, conscience, and so forth;

and we are constantly using these names as if everybody understood them

perfectly. What is customary and commonplace comes to be self-evident to

us and is quietly accepted; it arouses no wonder at its strangeness, no

curiosity which might lead us to examine it more closely. Popular

psychology remains unconscious of the fact that there are mysteries and

problems in these complexes. It loses sight of the complications because

of the simplicity of the names. When it has arranged the mental

phenomena in any particular case under the familiar designations, and

has perhaps said that some one has “paid attention,” or has “given free

rein to his imagination,” it considers the whole matter explained and

the subject closed.

Still a third condition has retarded the advance of psychology, and will

probably long continue to do so. Toward some of its weightiest problems

it is almost impossible for us to be open-minded; we take too much

practical interest in arriving at one answer rather than the other. King

Frederick William I was not the only person who could be persuaded of

the danger of the doctrine that every mental condition is governed by

fixed law, and that in consequence all of our actions are fully

determined--a doctrine fundamental to serious psychological research. He

believed that such a teaching undermined the foundations of order in

state and army, and that according to it he would no longer be justified

in punishing deserters from his tall grenadiers. There are even to-day

numerous thinkers who brand such a doctrine dangerous. They believe that

it destroys all possibility of punishment and reward, makes all

education, admonition, and advice meaningless, paralyzes our action, and

must because of all these consequences be rejected.

In a similar way the discussion of other fundamental questions, such as

the real nature of mind, the relation of mind and body in life and

death, becomes prejudiced and confused on account of their connection

with the deepest-rooted sentiments and longings of the human race. In

recent years this has been the case especially in connection with the

question of the evolution of mental life from its lower forms in the

animals to its higher in man. What ought to be taught and investigated

on its own merits as pure scientific theory, as the probable meaning of

experienced facts, comes to be a matter of belief and good character, or

is considered a sign of courageous independence of spirit and

superiority to superstition and traditional prejudice. All of this is

quite comprehensible when we consider the enormous practical importance

of the questions at issue. Yet such an attitude will scarcely be of much

help in finding answers most correct from a purely objective standpoint;

it rather discourages the advance of research along definite lines.

Nevertheless, as we have stated in the beginning, psychology has now

entered upon a positive development. What favorable circumstances have

made it possible to overcome, at least in part, the peculiar opposing

difficulties?

There are many; but in the end they all lead back to one: the rise and

progress of natural science since the sixteenth century. However, this

has made itself felt in two quite different ways; the force of the first

wave was increased to its full magnitude by a closely following second

wave. First, natural science served--if we overlook the hasty

identification of mind and matter which had its origin in natural

science--as a shining and fruitful example to psychology. It suggested

conceptions of mental life analogous to those conceptions which had been

found to make material processes comprehensible. It led to attempts at

employing methods similar to those which had proved valuable in natural

science. This influence was especially active in the seventeenth and

eighteenth centuries, and lasted into the nineteenth. Later a more

direct influence began to make itself felt: an actual invasion by

natural science of special provinces of psychology. Natural science, in

the course of its further development, was led at many points into

investigations which lay as well in the sphere of psychology as in its

own prescribed paths. When it attacked them and worked out beautiful

solutions for them, psychologists also received a strong impulse not to

stand aside, but to take up those problems themselves and pursue them

independently for their own quite different purposes. So it was in the

nineteenth century, especially in its second half.

Let us discuss more in detail a few particular results of this twofold

general influence.

As the first important fruit of that indirect advancement through

analogy, may be instanced the idea of the absolute and inevitable

subjection to law of all mental processes, which I have just said forms

the foundation of all serious psychological work. This was a familiar

idea as far back as the later period of ancient philosophy, but was

afterwards repudiated by the theological representatives of philosophy

and psychology in the Middle Ages. To be sure, they always felt more or

less attracted toward this view on account of the doctrine of the

omnipotence and omniscience of God. For if God is almighty, then there

can be no event in the future, either in the outer world or in the heart

of man, which does not depend entirely on him; and if he is also

all-knowing, or if in the eternity of God the human differences of past

and future altogether disappear, then the future must be already known

to God, and in consequence be fixed unalterably. But in spite of this

argument, these medieval thinkers felt bound to affirm a spiritual

freedom (that is, a merely partial determination) under the pressure of

popular psychological and ethical thought and in consequence of their

contemplation of the holiness and justice of God. For how could God have

willed the sinful deeds of man, or have caused them, even indirectly?

Or how could he punish men for doing things which they were compelled to

do by unalterable laws which he himself had made? Although, so it was

argued, man had his origin in God, he was nevertheless not absolutely

bound by the divine within him; he could turn away from it voluntarily,

that is, causelessly.

The influence of the rising natural science led to the opposite answer

to the question as to whether the basis of our responsibility is

spiritual freedom or universal causation. Hobbes and Spinoza became the

champions of universal causation, presenting their answer to the

question with a clearness and incisiveness imposing even to-day. Leibniz

too adopted it, but took care not to offend those holding to the other

view. It has never been lost again from psychology. These men teach that

the phenomena of the mental life are in one respect exactly like those

of external nature, with which they are indeed closely connected: at any

moment they are definitely fixed through their causes, and cannot be

otherwise than as we actually find them. Freedom of action in the sense

of causelessness is an empty concept. It follows from this that one can

properly mean by freedom of action only that there is no compulsion from

without, that the action of a thing or being is determined only by its

own nature, its own indwelling properties. We say of water that it flows

along freely if it is not checked by rocks or dams; or of a horse, that

it runs about freely, if it is not tied up or locked in a stall. We can

in this sense call the good deeds of a person or his living together

with other people his own free action, if it springs from his own

deliberations and desires and is not coerced by force or threats.

Nevertheless all these manifestations, the flowing, the running about,

and also the good actions, are alike the regular effects of definite

causes.

What constantly prevents men from recognizing this causality and leads

them to a belief in a misinterpreted freedom, is solely their ignorance.

Out of the multitude of motives for their actions they see, in most

cases, only a single one; and if the action which takes place does not

correspond with it, they are convinced that the decision occurred

without cause. “A top,” says Hobbes, “which is spun by boys and runs

about, first towards one wall then towards another, would think, if it

perceived its own motion, that it moved about by the exercise of its own

will, unless it happened to know what was spinning it.” In the same way

people apply for a job or try to make a bargain and think that they do

this by their own wills; they do not see the whips by which their wills

are driven. In order to understand correctly the thoughts and impulses

of man, we must treat them just as we treat material bodies, or as we

treat the lines and points of mathematics. The pretended dangers of such

a conception of things disappear, as soon as we face them without

prejudice and try to understand them. The conception may be misused,

especially by people of immature mind, but “for whatever purpose truth

may be used, true still remains true,” and the question is not, “what is

fit to be preached, but what is true.”

Supported by this view of a universal determination of mental activity,

there has arisen the idea of a special determination, likewise copied

from natural science. The coming and going of our thoughts is ordinarily

considered as an unregulated play, defying calculation. That order rules

even here, that the train of thought is governed by similarity to the

mental states just present, or by a previous connection with these

mental states, was clearly recognized and expressed even in the times of

Plato and Aristotle. Yet this had remained merely the knowledge of a

curiosity; no theoretical use whatever was made of it. Now it was

brought into connection with newly recognized physical facts. This

determination of the trains of thought depends, according to Hobbes, on

the fact that our ideas are connected with material movements within the

nerves and other organs, and that these movements, when once started,

cannot immediately cease, but must gradually be consumed by resistance.

The laws of association are to him in the spiritual sphere, what the law

of inertia is in the physical. To Hume, a hundred years later, they

depend on a kind of attraction, an idea suggested by Newton’s law of

gravitation. And since inertia and attraction had been recognized as the

most important and fundamental causes of material processes, it was a

natural thing to regard the laws of association, which had been compared

with them, as the fundamental phenomena of mental life, and to derive

from them as manifold and important consequences as had been done in the

case of the physical world. So arose the English associational

psychology. It attempted to explain the traditional faculties of the

mind, such as memory, imagination, judgment, and also the results of

their combined activity (for instance, the consciousness of self and of

the outer world) as natural and, so to speak, mechanical effects of the

laws of association governing the processes of mind. No doubt this

attempt, appearing also in a somewhat different form in the

sensationalism of France, represents, in spite of its one-sidedness, a

very great advance over the psychology of the past.

Just as associationism corresponds to the explanatory natural science of

Galileo and Newton, the empirical psychology of the German

enlightenment corresponds to the descriptive science of Linnæus and

Buffon. But aside from a few exceptions, such as Tetens, its work must

be regarded as a failure. To be sure, its intention is also to explain

mental phenomena, to comprehend them first by careful introspection, and

then to find by analysis the simplest faculties from which they have

sprung. But its actual accomplishment does not go beyond a mere

description of the occurrences offering themselves to first observation.

And the results reached teach impressively that description is an

unfruitful task unless, as sometimes of late, it is made to include also

explanation. The numerous different expressions of mind, already

distinguished by popular psychology, are only arranged in certain groups

beside and above each other, and the explanation consists in presenting

each expression as the effect of a special faculty. Thus we obtain a

great multitude of complicated mental performances, inwardly related to

each other, which are made to stand on a footing of equality and perfect

independence, for example, perception, judgment, reason, imagination,

and also abstraction, wit, symbolism, and so on. Like mere little

_homunculi_ in the large _homo_, they act now in harmony, now in

opposition. The poetic faculty, for example, “is a coöperation of

imagination with judgment.” In connection with reason, imagination

produces foresight. “Wit often does harm to judgment, and leads it to

false verdicts.... Judgment must therefore be constantly on its guard

against wit.” The advancement in this case did not result from a

development of these views, but from their overthrow. But the opposition

raised was turned also against associationism.

Of the defects of associationism this is the greatest: it gives no

explanation of the phenomenon of attention. The peculiar fact that of a

great number of conscious impressions or ideas simultaneously offered to

the mind, only a few can ever be carried through and become effective,

is not to be explained on the basis of the associative connection of

ideas. The associationists pass over this important fact either with

complete silence or with a very insufficient treatment, and thus put a

weapon into the hands of their opponents. The mind seems, in fact, in

the case of attention to mock at all attempts at explanation and to

prove itself, quite in the sense of the popular conception, a reality

separable from its own contents--standing face to face with them, and

treating them capriciously now in one way, now in another.

It is the chief service of Herbart to have recognized a weak point here,

and to have attempted to remedy it. “The regularity of the mental life,”

he is convinced, “is fully equal to that of the movements of the stars.”

Physical analogies guide him in his attempt at explanation. He regards

ideas as mutually repellent structures, or, as it were, elastic bodies,

assigned to a space of limited capacity, forced together and made

smaller by mutual pressure, but never annihilating each other. If

several ideas are simultaneously called forth, they become conflicting

forces, on account of the unity of the mind, in which they are compelled

to be together, and on account of the opposition which exists among

them. In this struggle their clearness suffers and their influence on

consciousness is impaired. However, they do not perish, but become, to

the extent that they suffer, latent forces.

As soon as the opposing factors lose their strength these latent forces

emerge again into full consciousness out of the obscurity in which they

have been buried. After making some further simple assumptions as to the

strength of these interferences, Herbart concludes that two ideas are

sufficient to crowd a third completely out of consciousness. To his

great satisfaction he thus gains from the consideration of a simple

mechanism “a solution of the most general of all psychological

problems.” By this problem he means the fact that of all the knowing,

thinking, wishing, which at any moment might be brought about by the

proper causes, only a very small part plays a significant rôle, while

the rest is not really lost. That is, he means the fact of attention.

But this principle of the mutual interference of ideas is not the only

one he uses. The second principle upon which his theory is based is that

of association. With these two weapons he takes up the fight against the

faculty psychology, and carries it to a successful end. He believes that

all those activities traditionally placed side by side, even feeling and

desire, can be made comprehensible as results of the mechanics of ideas.

Yet Herbart seeks by still another means to “bring about a mental

science similar to the natural science: ... by quantitative methods and

the application of mathematics.” We find here and there before this time

the idea of advancing psychology by such means. The brilliant results

produced in natural science by measurement and calculation readily

suggested the idea that something similar might be done for psychology.

But the philosophical thinkers interested in psychology did not find the

right tools; they justified their inability by asserting that such an

undertaking was impossible. The most famous is the denial by Kant that

mathematics can be applied to the inner mental life and its laws,

because time, within which the mental phenomena would have to be

represented as occurring, has but one dimension. To be sure Herbart is

not actually the pioneer in this field: he never gave a single example

of how a measurement of a mental process was to be taken. However, he at

least recognized that the mental life is open to quantitative treatment,

not only with regard to time, but also in other respects. And in

attempting to solve problems quantitatively, through the statement of

numerical assumptions and their logical development to their

consequences, he so strongly emphasized a side of the matter which had

previously been wholly neglected, that more correct ways of clearing it

up were soon found.

A strong and enduring influence was exerted by Herbart, yet the further

progress of psychology did not occur along the path marked out by him.

Many of his general assumptions, particularly those upon which his

calculations are based, were entirely too vague to appear probable

merely because a few of their consequences agreed with experience.

Besides, a strong opposition had arisen against the intellectualism

supported by him and by the associationists,--against the almost

exclusive regard for the thinking and knowing activities of the mind. If

mental life is really nothing but a machinery of ideas, a coöperation

and opposition of masses of ideas, what is such a thing as religion? Is

it a small complex of true and rational ideas, to which is added a large

complex of superstitious fables, invented, or at any rate cultivated, by

priests and princes, in order to keep men under their authority? So low

a valuation of religion is scarcely possible. Or, what is art? Are the

lyric poems of Goethe or the symphonies of Beethoven really only

institutions for the conveyance of knowledge through the senses, as the

name _esthetics_ indicates, or for the unsuspected instilling of ideas

which make men more virtuous or more patriotic?

Certainly one thing which stands in the center of all mental life seems

entirely incomprehensible as the result of a mere mechanics of ideas,

that is, that unity of mind without which we could not speak of

personality, of character, of individuality, without which we could not

call one man haughty and another humble, one good and another bad, one

noble and another base. Because of this weakness in the theory numerous

great thinkers, Rousseau, Kant, Fichte, Schopenhauer, raised their

voices to insist upon the significance of the life of feeling and will

as well as of the life of ideas, even to give to the former the first

place, as the expression of mind’s most real inner being. Thus

intellectualism was opposed by what we now call voluntarism.

This transferring of the conceptions of natural science to psychological

research, in spite of the mighty impulse it gave to psychology, was not

without its disadvantage. The first brilliant advances in natural

science were in the province of physics, especially of mechanics. It is

no wonder, then, that psychologists, in their gropings after something

similar, turned first to mechanical-physical processes. Inertia,

attraction, and repulsion, as we have seen, aggregation and chemical

combination, were the categories with which they worked. No wonder,

either, that facts were often distorted and their comprehension made

difficult. For if mind is a machine, it is certainly not such a machine

as even the most ingeniously constructed clock or as a galvanic battery.

It is bound up with the organic body, especially with the nervous

system, and on the structure and functions of the nervous system its own

existence and activity somehow depend. So, if one wishes to use material

analogies and to make them fruitful for the comprehension of mental

structures, they must be taken from organic life, from biology rather

than from physics and chemistry. We may find phenomena comparable to

individuality and character, to the mind’s feeling and willing, in the

unitary existence of every plant and animal organism, in the peculiar

determination of its instinct of life and in the many special branches

into which this instinct ceaselessly unfolds. And indeed the

specifically mechanical categories gradually disappeared from psychology

during the nineteenth century, and made way for the biological

categories--reflex, inhibition, practice, assimilation, adaptation, and

so on. Especially that great acquisition of modern biology, the theory

of evolution, was at once seized upon by psychologists, and was utilized

for gaining an understanding of the processes as well in the mind of the

individual as in human society.

But side by side with such advances, springing from analogy and

adaptation, there arose in the nineteenth century another and more

direct influence of natural science, as previously mentioned. In its

natural progress scientific research came to touch upon psychological

problems at several points, and since it laid hold of them and followed

them out for its own ends, it immediately became a pioneer for

psychology.

The first and at the same time the strongest of these impulses came from

the advance of the physiology of the senses. In the fourth decade of the

nineteenth century remarkably active and fruitful work in this field

began. Physiologists and physicists vied with each other in accurate

study of the structure and functions of sense organs. Naturally they

were not able to stop at the material functions in which they were most

directly interested. They could not forbear to draw into the circle of

their investigations those mental functions mediated by the

physiological functions and explainable on a physiological basis. The

eye, especially, attracted scores of investigators, both because it is

very richly endowed with dioptric and mechanical auxiliary apparatus and

because it is particularly important on account of the delicacy and

diversity of its functions. Yet cutaneous sensations and hearing were

not neglected.

Johannes Müller, E. H. Weber, Brewster, and above all--especially

versatile, far-seeing, and inventive--the somewhat younger Helmholtz,

are only a few of the most noteworthy representatives of this class of

research. They brought to psychology results such as it had never known

before--results resting on well-conceived and original questions as to

the nature of things, and on skillful attempts at arranging the

circumstances for an answer, that is, on _experiment_ and when possible

on exact _measurement_ of the effects and their causes. When Weber in

1828 had the seemingly petty curiosity to want to know at what distances

apart two touches on the skin could be just perceived as two, and later,

with what accuracy he could distinguish between two weights laid on the

hand, or how he could distinguish between the perception received

through the muscles in lifting the weights and the perception received

through the skin, his curiosity resulted in more real progress in

psychology than all the combined distinctions, definitions, and

classifications of the time from Aristotle to Hobbes. The surprising

discovery of hitherto unknown sense organs, the muscles and the

semicircular canals, was made at that time, although not thoroughly

verified until later. That discovery meant not only an increase of

knowledge, but also a widening of the horizon, since the most

conspicuous peculiarity of these organs is that they do not, like the

others, bring to our consciousness external stimuli in the ordinary

sense, but processes on the inside of the body.

One result in particular of these investigations in the physiology of

the senses became the starting point of a strong new movement. The

course of biology in the second quarter of the nineteenth century was

toward methodical and exact study of empirical facts, and away from

speculation in the philosophy of nature. But for some time this exact

study and this speculation were often to be found combined in the same

men. Fechner was one of these. On the one hand he was a speculative

philosopher, a follower of Schelling’s philosophy of nature, a disciple

of Herbart in his attempt at applying mathematics to psychology. So we

find him speculating as to what might be the exact relations between

body and soul, seeking for a mathematical formulation of the dependence

of the corresponding mental and nervous processes. One October morning

in 1850, while lying in bed, he conceived a formula which seemed to him

plausible. In spite of this speculative tendency he was a physicist of

scientific exactness, accustomed to demand a support of facts for such

plausible formulas, ready to attack problems not only with his mind, but

also with his hands. In following up his speculations he came across

some of the results of the work of Weber. By the use of more exact

methods and by long-continued series of experiments he carried Weber’s

investigations farther, at the same time utilizing the observations of

others to which no one had before paid any attention. He succeeded in

formulating the first mathematical law of mental life, Weber’s law as he

called it, according to which an increase of the external stimulus in

geometrical progression corresponds to the increase of the mental

process in arithmetical progression. (We shall discuss this law in §

4.) He classed together all of his speculations, investigations,

formulations, and conclusions as a new branch of knowledge,

Psychophysics, “the scientific doctrine of the relations obtaining

between body and mind.”

Fechner’s work called forth numberless books and articles, confirming,

opposing, discussing it, or carrying its conclusions still further. The

chief question which they discussed, the question whether the law

formulated by Fechner was correct or not, has gradually lost its

importance, and made way for other problems. Quite aside from this

question, which originally formed the center of interest, Fechner’s work

has made itself felt in three different ways. Herbart’s mathematical

fiction of the combat among ideas had made such an impression upon the

thinkers of the time, that--incredible as it may seem--as late as 1852

Lotze confessed that he would prefer it to formulas found by experiment.

For this fiction Fechner substituted a scientific law derived from

actual measurement of physical forces. Further, he gave to these facts

their proper place in a broad system, showed their significance for the

deepest psychological problems, and thus compelled even those

psychologists who had affiliated themselves with philosophy and had

previously remained unaffected by the physiology of the senses, to take

notice of the new movement in their science. And finally, he worked out

a methodical procedure for all psychophysical investigations, which was

far superior to the methods then employed by psychologists and which

continues to be of great use for the study of sensation and perception.

At about the same time, in the sixties, psychology received a third kind

of impulse. Although weaker than the two just mentioned, it contributed

not a little toward increasing the number of psychological problems to

which experimental methods could be applied.

In the year 1796 the Reverend Nevil Maskelyne, director of the Greenwich

observatory, noticed that the transits recorded by his assistant,

Kinnebrook, showed a gradually increasing difference from his own,

finally amounting to almost a full second. He suspected his assistant of

having deviated from the prescribed method of observation, the so-called

eye and ear method, and of having substituted some unreliable method of

his own. He admonished the young man to return to the correct method and

do better in the future. But his admonition was in vain, and he found

himself obliged to part with his otherwise satisfactory assistant.

Kinnebrook lost his position on account of the deficient psychological

knowledge of his time. It was not until two decades later that Bessel

discovered that such differences between the results of observations by

different individuals were quite general and normal, and that in

Kinnebrook’s case they were only unusually great. They depend on the

manner of giving attention to both the sound of the pendulum and the

sight of the moving star, which naturally differs in different

individuals.

At first this question of the so-called personal equation remained a

purely practical astronomical problem. But a few decades later it gave

rise to two classes of investigations of psychological importance, both

of the experimental kind. The first was an investigation of a

comparatively simple problem--the duration of the mental processes.

Among such processes measured were the simple perception, the

discrimination of several perceptions, the simple reaction to them, the

reproduction of any suggested idea, the reproduction of a specific

suggested idea, and so forth. Not only was the duration of these

processes studied, but also their dependence on differences of

stimulation, the accompanying circumstances, the individual differences,

the subject’s trend of thought. The second class of investigations was

concerned with the more complex mental processes of attending and

willing. As examples may be mentioned inquiries into the attention of a

person confronted by a multitude of impressions, a study of the order in

which the several impressions are perceived, a determination of the

largest number of impressions perceptible as a mental unit, and research

into the causal relations between ideas and actions.

A more recent contribution of natural science to the advancement of

psychology has come from investigations in the physiology and pathology

of the central nervous system since the discovery about 1870 of the

so-called speech center by Broca, and of the motor areas of the brain

cortex by Fritsch and Hitzig. Some have placed a rather low value on

this contribution and, noticing the errors and immature conceptions of

this or that investigator, have arrived at the conclusion that

psychology can learn nothing worth mentioning from the work of these

men. This, it seems to me, is a great mistake.

Quite aside from innumerable details, psychology owes to the

investigations made in recent years concerning the physiology of the

brain two fundamental conceptions. In the first place it has come to be

generally recognized that the search of centuries for the exact seat of

the soul in the brain--for the point where mind and body come into

interaction--is without an object. There is no seat of the soul in this

sense; the brain is the embodiment of almost absolute decentralization.

Our mind receives the impressions of the external world by means of

widely separated parts of the brain, as different sensations, according

to the peripheral organs stimulated. And our mind controls our actions

by means of widely separated parts of the brain according to the local

differences of the muscle groups which are called into action. All the

parts of the brain are connected, but they function in relative

independence, without being controlled from a single point. Now, it is

clear that insight into this fact is of no little significance for our

conception of the nature of mind.

In the second place it is only through the work of these neurologists

that psychologists have come to realize how enormously complicated are

even those mental functions which have always been regarded as

comparatively simple. That the speech function, for example, involves

consciousness of sound, of movement, and sometimes of sight, may be

recognized immediately, and has been recognized. That our images of

things are directly nothing but revived sense impressions of various

kinds, visual, auditory, olfactory, and so on, and that our skill in

handling things depends upon our experience obtained through running our

fingers over them, is also recognized. But that all these images are

more than abstractions, that they have a concrete significance even

though the subject may not be aware of them, has been recognized only

after the study of pathological cases, where, in consequence of peculiar

lesions of the brain a dissociation has occurred among those factors

which usually work together harmoniously, and where some of them are

perhaps entirely lost. It was not until these pathological facts were

known that psychology was able to give a definite formulation to certain

of its problems. It then became clear that many former problems which

took their origin from those popular simplifications, will, judgment,

memory, or from the seeming simplicity of ideas and movements, were

perfect nonsense, considering the actual complexity of the facts. Now,

after having learned how to formulate its problems, psychology can at

last hope to understand the phenomena of mental life.

The study of the brain has also had an indirect influence upon

psychology through the strong impulse which it gave to psychiatry. The

knowledge gained in the study of the abnormal mind gave a new insight

into the processes of the normal mind. And since psychiatrists most

often came into contact with the highly complex mental states, such as

emotion, intelligence, self-consciousness, the impulses which they gave

to psychology were a happy supplement to those other influences which

concerned chiefly sensation and perception.

* * * * *

During the last decades of the nineteenth century all these buds of a

new psychology were--first by Wundt--grafted on the old stem and so

united into an harmonious whole. They have rejuvenated the apparently

dying tree and brought about a strong new growth. The psychology of the

text-book and the lecture room has become a different science. The most

conspicuous sign of this new conception of the science of the mind is

the establishment of numerous laboratories exclusively devoted to

psychological research.

In earlier times psychology was but the handmaid of other interests.

Psychological research was not an end in itself, but a useful or

necessary means to higher ends. Usually it was a branch or a servant of

philosophy. Men took it up particularly in order to understand the

foundations of knowledge, or how our conceptions of the natural world

originated, and this again in order to draw metaphysical or ethical

conclusions, to settle the controversy between idealism and

materialism, to answer the question as to the relation of body and mind,

to derive rules for a rational conduct of life, often also with the mere

purpose of confirming views springing from some other source. Others

took up the study of psychology with a practical aim, for example, in

order to find out how to make the most of their lives, or how to improve

their memories. It is, to be sure, greatly to be hoped that psychology

will not entirely lose its connection with philosophy, as natural

science has unfortunately done. At no time, indeed, has the practical

importance of psychology, its great usefulness in education, psychiatry,

law, language, religion, art, been more strongly felt, or given rise to

more numerous investigations than at present. But it is now recognized

that, here as elsewhere, it is more fruitful for the true and lasting

advancement of philosophical ends, instead of always thinking of

advancing them, to forget them for the time, and to work on the

preliminary problems as if these preliminary problems were the only ones

existing. And so psychology, formerly a mere means to an end, has come

to be regarded as a special science, to which a man can well afford to

give his full time and energy.

A few data may illustrate what we have just said. Until the last decades

of the nineteenth century psychology has not been able to support a

journal of its own. A few attempts in this direction were made in the

eighteenth century, when two psychological periodicals were started; but

neither published more than a few volumes. Even in the middle of the

last century magazine articles of psychological content were rare enough

and appeared only in philosophical, physiological, or physical journals.

During the last thirty years a complete revolution has taken place in

this respect, more remarkable than in any other branch of science.

First at longer intervals, then in quick succession, numerous purely

psychological journals were founded in the principal civilized

countries, of which none thus far has been compelled to retire on

account of lack of either contributors or readers. We count at present

at least fifteen, six of them in German, four in English, three in

French, one in the Italian language, and one representing the

Scandinavian peoples. And there is an equal number of periodical

publications of single investigators and institutions, and also numerous

writings of psychological importance published in philosophical,

physiological, psychiatrical, pedagogical, criminological, and other

journals.

QUESTIONS

1. How old is the science of psychology?

2. What do you know about its early growth?

3. What are the difficulties besetting psychology?

4. What is the origin of popular psychology?

5. Why is psychology so much hampered by prejudice?

6. State the two ways in which psychology has been influenced by

natural science.

7. How was psychology influenced by medieval theology?

8. Who were the opponents of theological psychology?

9. What does freedom of action mean?

10. What kind of ignorance is the cause of the belief in absolute

freedom?

11. How did the associational psychology originate?

12. What is meant by the faculty psychology?

13. What does psychology owe to Herbart?

14. What is voluntarism?

15. Why are mechanical explanations of mental life inadequate?

16. From which science can psychology obtain the most fruitful

analogies?

17. Which science gave in the earlier part of the nineteenth

century the strongest direct impulse to psychology?

18. What is psychophysics and who is its author?

19. What is meant by the personal equation?

20. What experimental investigations were suggested by the personal

equation?

21. How did the study of the physiology of the brain influence

psychology?

22. Is psychology a special science?

CHAPTER I

GENERAL PSYCHOLOGY

§ I. BRAIN AND MIND

As we all know, the processes of our mental life stand in the closest

relationship with the functions of the nervous system, especially with

the functions of its highest organ, the brain. Local anemia, that is, a

lack of blood in the brain, causes fainting, a cessation of

consciousness; on the other hand, during mental work the blood pressure

in the brain is higher than usual and metabolism is increased. Narcotic

or poisonous drugs, as alcohol, caffein, and morphine, which influence

mental activity, do this by means of their effect on the nervous system.

Aside from such experiences, there are two special groups of facts upon

which our knowledge of this relationship is based.

First the dependence of mental development on the development of the

nervous system. This is most conspicuous when man and animals are

compared. It is somewhat obscured, however, by the relation of the size

of the brain to the size of the animal. The larger animal has as a rule

the larger brain. Therefore the brain of man can be compared only with

the brain of such animals as are of nearly the same size. When such a

comparison is made, man is found to be no less superior in nervous

organization than in intelligence. His brain is about three times as

heavy, absolutely and relatively, as that of the animals most nearly

approaching him, the anthropoid apes; eight to ten times as heavy as

the brain of the most intelligent animals lower down in the scale, for

instance large dogs. Similar relations between brain weight and

intelligence are found in the human race itself. Of course, we cannot

expect that this relation will always be found in a comparison of only

two individuals. The conditions are too complex for such a regularity to

exist; but it is easily demonstrated when averages of groups of

intelligent and unintelligent men are compared. We do not expect,

either, that in every individual case physical strength is exactly

proportional to the weight of the muscles, although no one doubts that

strength depends on the weight of the muscles.

The second of the facts upon which our knowledge of the relationship

between mental life and nervous function is based, consists in the

parallel effects of disturbances of their normal condition. Diseases or

injuries of the brain are, as a rule, accompanied by disturbances of the

mental life. On the other hand, mental disturbances can often be traced

to lesions or structural modifications in the brain. This cannot be done

in every case; but the actual connection is none the less certain. It is

often very difficult to decide whether or not any mental abnormality

exists. Expert psychiatrists have for weeks at a time observed men

suspected of mental disease without being able to pronounce judgment.

Equally difficult is the discovery of material changes in the brain and

its elements. Much progress has been made in recent times in this

respect; but it is still far from easy to recognize the more delicate

changes in nervous structure resulting from disease. Certain

abnormalities may never become directly visible although they involve

disturbances of function, for instance, abnormalities in the nutrition

of the nervous elements or changes in their normal sensitivity. No

wonder, then, that for many mental diseases, as hysteria, corresponding

material lesions are not yet known. But the correctness of our thesis is

so strongly secured by the enormous number of cases in which it has been

demonstrated, that no one doubts that it applies also to those cases in

which, often for good reasons, its demonstration has thus far been

impossible.

Of much importance is the particular form of this relationship between

brain function and mental life. Popular thought attributes the chief

classes of total mental activity to special parts of the brain. Judgment

is thought to have its seat behind the thinker’s high forehead. The

occipital part of the brain is, according to the medieval philosophers,

the organ of memory. And so Gall’s phrenology met with ready acceptance

from the public at large, which was delighted to learn that musical

ability, mathematical talent, religious sentiment, egotism and altruism,

and many other character traits had their special organs in the brain.

But anatomists and physiologists have not been able to admit the

plausibility of this doctrine.

Yet popular thought has, on the other hand, always emphasized the unity

of mind. Those who regard its unity as the chief characteristic of mind

have for centuries sought for the single point in the brain where the

mind can be said to have its seat. If it were distributed all through

the brain, would it not be possible to cut the mind into pieces by

simply cutting the brain?

That both these views of the relation between brain and mind are

inadmissible has become certain. Since about forty years ago the truth

in this matter has been known. But to understand it clearly it is

necessary first to familiarize ourselves with the construction of the

nervous system.

QUESTIONS

23. What do we learn from a comparison of brain weight and

intelligence?

24. What is the relation between nervous pathology and mental

abnormality?

25. Is phrenology admissible?

26. What view concerning the relation of brain and mind is

suggested by the unity of mind?

§ 2. THE NERVOUS SYSTEM

1. _The Elements of the Nervous System_

[Illustration: FIG. 1.--MULTIPOLAR CELL BODY.]

The number of elements making up the nervous system is estimated at

about four thousand millions. It will help us to comprehend the

significance of this number if we understand that a man’s life devoted

to nothing but counting them would be too short to accomplish this task,

for a hundred years contain little more than three thousand million

seconds. These elements are stringlike bodies, so thin that they are

invisible to the naked eye. They are generally called _neurons_. Within

them different parts are to be distinguished. The part which is most

important for the neuron’s life is a spherical, bobbin-shaped,

pyramidal, or starlike body, called the ganglion cell or cell body,

located usually near one of the ends of the long fiber of the neuron,

but sometimes nearer the middle of the fiber. The length of the fiber

varies from a fraction of an inch to several feet. The fiber may be

compared with a telephone wire, inasmuch as its function consists in

carrying a peculiar kind of excitatory process.

[Illustration: FIG. 2--PYRAMIDAL CELL BODY.

_a_, Nerve fiber with collaterals.]

[Illustration: Fig. 3.--DENDRITES OF A NERVE CELL OF THE CEREBELLUM.]

At both ends of the neuron are usually found treelike branches. When the

cell body is located near one of the ends of the fiber, many of these

branches take their origin from the cell body and give it the pyramidal

or starlike appearance illustrated by figures 1, 2, and 4. These

branches are called dendrites, from the Greek word for tree, _dendron_.

How wonderfully complicated the branching of a neuron may be is

illustrated by figure 3. In addition to the dendrites a neuron possesses

another kind of branches, resembling in character the tributaries of a

large river, entering into it at any point of its course. These are

called collaterals (lowest part of figure 2).

[Illustration: FIG. 4.--VARIOUS TYPES OF CELL BODIES.

_1_ and _2_, Giant pyramidal cell bodies; _n_, nerve fiber.]

[Illustration: FIG. 5.--LONGITUDINAL SECTION OF A NERVE FIBER WITH

STAINED FIBRILS.

_a_, Medullated sheath.]

The ganglion cells have a varying internal structure, which may be made

visible to the eye when the cells have been stained by the use of

different chemicals. They are found to contain small corpuscles with a

network of minute fibrils between them, as shown in figures 1 and 4. The

nerve fibers, too, in spite of being only 1/40 to 1/500 mm. thick,

permit us to distinguish smaller parts (fig. 5). The core consists of a

bundle of delicate, semi-fluid, parallel fibrils, the axis-cylinder.

This is surrounded generally by a fatty, marrow-like sheath, and in the

peripheral parts of the system this sheath is again inclosed in a

membrane. Certain fibers attain a considerable length, for example,

those which end in the fingers and toes, having their origin in the

spinal region of the body.

The treelike branches of the main fiber and of the collaterals, if far

away from the cell body, are sometimes called the terminal arborization,

from the Latin word for tree, _arbor_ (fig. 6). The treelike branching

has most probably a functional significance of great importance. It

enables the endings of different neurons to come into close enough

contact to make it possible for the nervous processes to pass over from

one neuron into another neuron, without destroying the individuality,

the relative independence of each neuron.

[Illustration: FIG. 6.--TERMINAL ARBORIZATION OF OPTICAL NERVE FIBERS.]

Wherever large masses of neurons are accumulated, the location of the

ganglion cells can be found directly by the naked eye. The fibers are

colorless and somewhat transparent. Where they are massed together, the

whole looks whitish, as is the case with snow crystals, or foam. The

ganglion cells, however, contain a dark pigment, and where many of them

are present among the fibers, the whole mass looks reddish gray.

Accordingly one speaks of white matter and gray matter in the nervous

system.

The nature of the excitatory process for the carriage of which the

neurons exist is still unknown. It is certain, however, that this

process is not an electrical phenomenon. Electrical changes accompany

the nervous process and enable us to recognize its presence and even to

measure it; but they are not identical with the nervous process.

Probably it is a kind of chemical process, perhaps analogous to the

migration of ions in the electrolyte of a galvanic element, the lost

energy being restored by the organism. Two facts are especially

noteworthy. The velocity of propagation has been found to be about 60

meters per second in the human nervous system. In the lowest animals

propagation is often considerably slower. It is clear, therefore, that

it is an altogether different magnitude from the velocities found in

light, electricity, or even sound.

A second fact is the summation of weak stimulations. The second one

produces a stronger effect than the first, the third again a stronger

effect, and so on. It also happens that a number of successive stimuli

produce a noticeable effect, whereas one of these stimuli alone, on

account of its weakness, would produce none. On the other hand, if

strong stimuli succeed one another, the effect becomes less and less

conspicuous. The neurons are fatigued, as we say, and require time for

recuperation.

2. _The Architecture of the Nervous System_

The elements of the nervous system just described are combined into one

structure according to a surprisingly simple plan, in spite of its

seeming complexity. This apparent complexity results chiefly from the

enormous number of elements entering into the combination. The purpose

of the nervous architecture may be briefly described thus: The

conductivity of the nervous tissue is employed to _bring all the sensory

points of the living organism into close connection with all the motor

points, thus making a body capable of unitary action out of a mere

accumulation of organs, each of which serves its specific end_. Walking

along and meeting an obstacle, I must be able first to look about and

find a way of pushing it aside or climbing over it, and then to push or

climb. This is impossible unless my eyes are connected with the muscles

of the head, the arms, the legs. Perhaps I am inattentive, or it is

dark, so that I run against the obstacle with my feet or my body. In

this case it is necessary that the sensory points of my skin be

connected with all those muscles. Hearing a call, I must be able to turn

my head so that I may hear more distinctly the sound I am expected to

perceive; but I must also be able to move my tongue and the rest of my

vocal organs in order to answer, or, as the case may require, my arms

and legs in order to defend and protect myself. Thus the ear and all

other sensory points of the body must be closely connected with all the

motor points.

It is plain, then, that the simplest kind of nervous system must consist

of three kinds of neurons: sensory (often called afferent), motor (often

called efferent), and connecting neurons. To improve the working of such

a system, the afferent and the efferent neurons, and especially the

connecting (associating) paths, are developed by the introduction of

additional neurons, serving to cross-connect the primary chains of

neurons. Figure 7 illustrates the architecture of an exceedingly simple

nervous system of the most rudimentary kind.

A perfection of the system is brought about by a superstructure built on

essentially the same plan. Figure 8 is a diagram illustrating this. The

points _S´_ and _M´_ correspond to the points of the same names in

figure 7. But several systems (three in the diagram) like that of figure

7 have been combined by connecting neurons in exactly the same manner in

which the combination was effected in figure 7. In this higher system

(nerve center, we should call it) the points _S´´´_ and _M´´_ have a

significance comparable to that of _S´_ and _M´_.

[Illustration: FIG. 7.--DIAGRAM OF NERVOUS ARCHITECTURE: REFLEX ARCHES

CONNECTED BY A LOW NERVE CENTER.

(From Psychological Review, 15, 1908.)]

[Illustration: FIG. 8.--DIAGRAM OF NERVOUS ARCHITECTURE: LOWER NERVE

CENTERS CONNECTED BY A HIGHER CENTER.

(From Psychological Review, 15, 1908.)]

Several of these larger systems (three in the diagram) are combined

again by means of connecting neurons in exactly the same manner as

before. This is illustrated by figure 9. The points _S´´´_ and _M´´´_

have a significance like that of _S´_ and _M´_, _S´´´_ being nearer to

sensory points of the body than to motor points, _M´´´_ being nearer to

motor points. This system of connecting neurons represents again what we

may call a higher nerve center--higher still than those which are

combined in it.

[Illustration: FIG. 9.--DIAGRAM OF NERVOUS ARCHITECTURE: HIGHER NERVE

CENTERS CONNECTED BY A STILL HIGHER CENTER.]

Thus we may conceive any number of systems, one still higher than the

other. And we may understand how it is possible that simpler mental

functions may enter into a combination, forming a unitary new function,

without completely losing their individuality as functions of a lower

order; for combinations of simple functions represented by _direct_

connections into complex functions are brought about only by mediation

of higher connecting neurons which represent the _less direct_

connections of sensory and motor points. The most manifold associations

are made possible. A practically inexhaustible number of different

adaptations is structurally prepared, so that the most complicated

circumstances and situations find the organism capable of meeting them

in a useful reaction. This type of nervous system is the property of the

highest animals and of man. The lower type of nervous system is

represented by the reflex arches of the so-called spinal and subcortical

centers. The higher type is represented by the cerebrum and cerebellum,

which during a process of evolution covering hundreds of thousands of

years have gradually been developed to serve as the highest centers of

the nervous system.

3. _The Anatomy of the Nervous System_

The most prominent part of the nervous system is that inclosed within

the skull and the vertebral column. The spinal cord runs all through

this column up to the skull. Entering into the skull, it thickens and

forms what is called the bulb (medulla oblongata). It then divides into

several bodies, which are referred to as the subcortical centers,

because they are located below the cortex, which is the surface layer of

the cerebrum, or large brain. These subcortical centers contain the

central ends of neurons which are links of chains of afferent neurons

coming from the higher sense organs and from the sensory points of the

skin and the internal organs. Chains of efferent neurons, on the other

hand, take their origin in the subcortical centers, reaching at their

peripheral ends the motor points of the body, that is, the muscle fibers

of our skeletal muscles and of the muscle tissues contained in the

alimentary canal and the other internal organs.

Above and partly surrounding the subcortical centers are the large brain

and the cerebellum or small brain. The ganglion cells of the neurons

contained in the cerebrum and cerebellum are all located near the

surface or cortex. There seems to be a peculiar advantage--not yet

perfectly understood--in having the gray matter spread out over the

surface of the cerebrum and cerebellum in as thin a layer as possible.

To this end the surface of the cerebrum is much increased by the

formation of large folds, separated by deep fissures (see figure 10).

In the cerebellum the folds are more numerous and exceedingly fine, and

they do not have the appearance of being the product of fissuration. The

surface of the cerebrum is estimated to be equal to a square with a side

eighteen inches long. Without the fissures the surface would be only

about one third of this. The mixture of ganglion cells and fibers making

up the gray matter of the brain is illustrated in figures 11 and 12.

Both are sections of the cortex of the cerebrum. In figure 11 the cell

bodies alone are stained and thus made visible; in figure 12 the fibers

alone are stained.

[Illustration: FIG. 10.--FRONTAL SECTION OF THE RIGHT CEREBRAL

HEMISPHERE.]

From what has been said thus far it is clear that certain areas of the

cortex must be connected with certain groups

[Illustration: FIG. 11.--SECTION OF THE CEREBRAL CORTEX.

Only the cell bodies are stained.]

[Illustration: FIG. 12.--SECTION OF THE CEREBRAL CORTEX.

Only the fibers are stained.]

of sensory points or motor points of the body much more directly than

with others. This is confirmed by histological, pathological, and

experimental investigations. For the eyes and the ears, for the muscles

of arms and legs, hands and feet, even the several fingers and toes, the

corresponding areas of the cortex--that is, the areas with which there

is direct connection--are definitely known. Figure 13 conveys an idea of

the relation between certain parts of the brain and the sensory and

motor organs of the body.

[Illustration: FIG. 13.--LOCALIZATION OF PERIPHERAL FUNCTIONS IN THE

CEREBRAL CORTEX.]

4. _The Nervous System and Consciousness_

We have already touched on the question as to the relation between the

nervous system and consciousness. It is evident that no single point of

the nervous system can be regarded as the long-searched-for seat of the

soul, since no single point is structurally or functionally

distinguished from all others. But it does not follow that mental

functions are localized in different parts of the brain according to

the popular conception of judgment, memory, will, and so on, each

depending on a special part of the brain. There is no more truth in the

similar assertions of phrenology. Localization of function in this sense

is impossible. Judgment is not a mental function which can be separated

from memory and attention. No more separable from each other are such

functions as religious sentiment, filial love, self-consciousness. The

sensational, ideational, and affective elements of these functions are

to a considerable extent the same.

Localization of mental functions really means this:--Since there is a

division of labor among the sensory and motor organs of the body, and

since each of these organs is most directly connected with certain areas

of the cortex and much less directly with the other areas, it is to be

expected that certain states of consciousness will occur only when

certain areas of the cortex are functioning. It is but natural that the

province of the cortex most directly connected with the eyes serves

vision, including both visual perception and visual imagination; that

the province of the cortex most directly connected with the ears serves

audition. Who would expect anything else? In the same sense, the

sensations of touch, of taste, and so on, are localized in the brain.

The same rule holds good for movements. When our limbs move in

consequence of some thought concerning them, the areas of the cortex

which are most closely connected with them must function, while other

areas may remain inactive. Activity of our vocal organs, in the service

of our mind, can occur only by the influence of that province of the

cortex which is most directly connected with the muscles of the vocal

organs. But how varied are the thoughts which may bring about action of

the vocal organs! On the other hand, how diversified may be the

movements by which a mother may react upon the crying of her child! In

either case it may be right to say that our mind is localized in the

brain as a whole--not, of course, equally in every infinitesimal

particle, but distributed through the brain in a manner comparable to

the distribution of the roots and branches of a tree.

QUESTIONS

27. To what kind of things are the neurons comparable?

28. How many neurons does the nervous system contain?

29. What kinds of branches does a neuron possess?

30. What are white matter and gray matter?

31. How does the velocity of a nervous process compare with other

velocities in nature?

32. What is the general function of the nervous system?

33. Can you draw a diagram illustrating the architecture of a

simple and of a more complex nervous system?

34. How can simpler nervous functions enter into a combination

without completely losing their individuality?

35. What is meant by subcortical?

36. What is meant by afferent and efferent neurons?

37. How large is the surface of the brain?

38. What is meant by sensory and motor areas of the cortex?

39. Where is the seat of the soul?

§ 3. EXPLANATION OF THE FUNCTIONAL RELATION BETWEEN BRAIN AND MIND

How the functional relation between the mind and the nervous system

should be explained, is a question discussed for centuries and variously

answered. But all the answers are essentially either the one or the

other of these two: (1) Either the brain is a tool of the mind, or (2)

it is an objectified conception of the mind itself.

1. _The Brain a Tool of the Mind_

Popular thought, supported by desires common to all human beings,

readily accepts the view that mind is essentially different from matter,

that its laws are in every respect different from the laws of material

nature, and that the brain, being a part of the material nature, is

simply the special tool used by the mind in its intercourse with nature.

Consider what a contrast seems to exist between logical certainty and

the mere probability derived from more or less deceptive sense

impressions, between voluntary attention and sensual desire, between

religious inspiration and ordinary perception, artistic creation and

everyday work. Nevertheless, these highest as well as the lowest

activities of the mind need a tool with which they can get into

communication with the world; and this tool, says popular thought, is

the brain. By means of this tool the mind can take possession of the

world and shape it at will. This explanation of the functional relation

between the mind and the nervous system agrees well with the facts above

discussed concerning brain weight and intelligence, and nervous

pathology and mental abnormality. That the magnitude, the architecture,

the normal condition of a tool have an influence on the task performed,

is plain enough. Many a piece of music can be played on a large organ

having a great variety of stops, whereas its performance on a small

instrument would be impossible. Raffael might have deserved the name of

a great painter if born without arms, but the world would never have

known it.

The facts of localization of function, however, do not agree so well

with this tool conception of the brain, which always leads us back again

to the theory that the mind takes hold of its tool at a single point. If

the mind can suffer or produce _this_ change only here, _that_ change

only there, it is difficult to see why we should regard it as an

altogether separate entity. Some have pointed out, as an analogy, that

truth too is everywhere, and because of its absolute unity, everywhere

in its totality, without being bound to space and time. I must doubt,

however, if truth is present where such analogies are worked out, for

nothing can be less clear than the assertion that truth has unity. Mind

is not everywhere in its totality, neither in the brain nor in the whole

world. It is partly here, partly there; as seeing mind it is in the

occipital convolutions of the brain, as hearing mind in the temporal

convolutions. Thus we are forced, if we regard the brain as the mind’s

tool, to regard the mind as an entity possessing spatial form. If we

reject this conclusion, we must also reject the premise that the brain

is the mind’s tool.

There are two other difficulties of very considerable importance. One of

them is compliance with the principle of the conservation of energy. If

mind is an entity independent of the brain, if the brain is a tool which

mind can use arbitrarily, without having to obey the laws of the

material world, there would be a serious break in the continuity of

natural law, and the principle of the conservation of energy would

suffer an exception.

Until recently it was, not probable, but at least possible, that this

principle of the conservation of energy was not strictly correct when

applied to conscious beings, especially to man. But in recent years

direct experiment has proved that it applies to the dog, and even to

man. In an animal performing no gross muscular work the energy supplied

by the food is completely transformed into heat, which is absorbed by

the animal’s surroundings. Rubner has found as the result of very exact

measurements that the heat produced by an animal during several weeks

is within one half of one per cent (that is, within the probable error)

equal to the quantity of chemical energy received from the food. One

might think that it would be rash to apply conclusions reached by

experimenting on a dog to man, whose mental life stands on a much higher

level. But even this objection has been removed by Atwater. He performed

similar experiments on five educated persons, varying the conditions of

mental and muscular activity or relative rest. The result is the same.

Taking the total result, there is absolute equality between the energy

supplied and the energy given out; in the human organism, mind has thus

been proved to be subject to the laws of the natural world.

The second difficulty spoken of consists in the fact that, accepting the

view which regards the brain as the mind’s tool, we cannot well avoid

regarding the mind as a kind of ghost or demon, similar to the demons

with which the imagination of primitive peoples populates the

universe--gaseous and usually invisible men, women, giants, or dwarfs.

Mankind has always felt strongly inclined to believe in the existence of

such demons, and is still fond of making them the subjects of fairy

tales and similar stories. But the more mature experience of the last

centuries of human history has eliminated them from our theories of the

actual world and assigned them their proper places in tales and

mythology. Winter and summer, rain and sunshine, even the organic

processes in the heart or the spinal cord are understood only by

excluding from the explanation the assumption of such demons. The same

is by analogy true for the processes in the brain, for the brain is not

likely to be an exception to the rule. It is more difficult, of course,

to determine directly whether such a demon exerts his influence in the

inaccessible cavity of the skull than it is on the street or even in a

haunted house. But no assertion is entitled to be regarded as true

merely because we cannot go to the place in question and observe that it

is false. Why not assert that heaven is located on the back side of the

moon and hell in the center of the sun, merely because no one can see

with his own eyes that they are not there? We must make only those

assumptions which, considered from all points of view, have a high

degree of probability, not those which flatter our vanity or appeal to

us as the fashionable belief of the time. Now, it does not seem probable

that our brain is the residence of a separable demon, no matter whether

we attribute to him the power of changing at will the total amount of

energy contained in our body, or conceive his activity, as some

psychologists do, as a new form of energy added to the mechanical,

thermal, electric, chemical, and so on,--requiring only an additional

transformation of energy and not breaking down the principle of its

conservation.

2. _The Brain an Objectified Conception of the Mind_

If we cannot regard the brain and the mind as two independent entities,

scarcely any other conception of them is possible except as a single

entity of which we may obtain knowledge in two ways, an objective and a

subjective way. _Mind_ knows itself directly, without mediation of any

kind, as a complex of sense impressions, thoughts, feelings, wishes,

ideals, and endeavors, non-spatial, incessantly changing, yet to some

extent also permanent. But _mind_ may also be known by other minds

through all kinds of mediations, visual, tactual, and other sense

organs, microscopes and other instruments. When thus known by other

minds, mind appears as something spatial, soft, made up of

convolutions, wonderfully built out of millions of elements, that is, as

brain, as nervous system. By mind and brain we mean the same entity,

viewed now in the aspect in which mind knows itself, now in the aspect

in which it is known by other minds.

Suppose a person is asked a question and after some hesitation replies.

In so far as this act is seen, heard, and otherwise perceived (or

imagined as seen, heard, or otherwise perceived), it is a chain of

physical, chemical, neurological, etc., processes, of material processes

as we may say. But that part of the chain of material processes which

occurs in the nervous system may not only be known by others, but may

know itself directly, as a transformation of perceptual consciousness

into thought, feeling, willing. The links of these two chains of

material processes in the brain and of mental states should not be

conceived as intermixed and thus forming one new chain, but rather as

running parallel--still better as being link for link identical. The

illusion that one of these chains brings forth the other is caused by

the fortuitous circumstance that they do not both become conscious at

once. He who thinks and feels cannot at the same time experience through

his sense organs the nervous processes as which these thoughts and

feelings are objectively perceptible. He who observes nervous processes

cannot at the same time have the thoughts and feelings as which these

processes know themselves. Those objective processes, however, which go

on outside of the nervous system, in particular those outside of the

experiencing organism, in the external world, precede or follow mental

states as causes generally precede their effects and effects follow

their causes. There is no objection to speaking of a causal relation

between material processes of this kind and mental states.

Whatever explanation of the functional relation between brain and mind a

person may accept, he need not constantly be on his guard lest he be

inconsistent. We speak of the rising and setting sun without meaning

that the earth is the center of the universe and that the sun moves

around it. So we may also continue to speak quite generally of the

material world as influencing our mind, and of the mind as bringing

about changes in the material world.

Our view of the relation between body and mind leads to the further

conclusion that, as our body may be distinguished from its parts without

having existence separate from its parts, so our mind may be

distinguished from the several states of consciousness without having

existence separate from them. Mind is the concept of the totality of

mental functions. As self-preservation is the chief end of all bodily

function, so self-preservation is the chief end of mental life.

QUESTIONS

40. Do the facts of comparative anatomy and of localized function

agree with the view that the brain is the mind’s tool?

41. Is mind subject to the law of the conservation of energy?

42. Is mind a demon interfering with the laws of nature?

43. What is the cause of the illusion that nervous processes bring

forth mental states, or that mental states bring forth nervous

processes?

44. Why is it correct to regard certain events going on outside of

the organism--and even in the organism, but outside of the nervous

system--as effects or as causes of certain mental states?

45. Is there any objection to distinguishing our mind from the

several mental states?