Outlines of psychology : dictations from lectures

Preface

The translation of Lotze's Grundznege der Psychologies which forms the principal part of this book, was made in 1882, and it was- expected to publish it at once. Circumstances prevented, for the time, the carrying out of the plan, but lately a personal need of some small text book to use in connection with the study of comparative anatomy in the scientific department of an Undergraduate course led to its revival. This circumstance explains why the short chapter on anatomy has been appended unnecessarily, as it may seem. It is believed that, in its present form, this volume will prove convenient: firstly, for use in connection with the little that can usually be said upon the physiology of the nervous system in the comparative anatomy of our ordinary colleges, at the same time furnishing a thoroughly reliable foundation upon which to add the more extended work in psychology; secondly, as a first book of psychology where for any reason the physiological side does not receive special attention in the philosophical department. Of the value of Lotze's little work nothing need be said here, the great German philosopher is rapidly gaining recognition even in

IV PREFACE.

America, while the series of " Outlines." of which this forms a part, has been exceedingly well received abroad. Attention may be asked, however, to the fact that these are but outlines, and embrace but the dictated portions of au extended lecture course. Their use in the school room implies oral explanation and illustration, or, better, they may form the frame work for a lecture course which may deal as fully with anatomical and physiological details as time permits. It is a matter of regret that no English work in this department has as yet appeared which is not devoted to the indirect inculcation of a theory (unorthodox or otherwise), or for some other reason un adapted to place in the hands of college students. Of the writer's part of the work it is not becoming to speak further than to express the hope that the sacrifice of literal accuracy will be found to have been attended with compensating advantages in perspicuity. The very forcible and colloquial style, which is so striking in the original, is verv hard to imitate, and one may be satisfied if the attempt prove intelligible.

Table Of Contents

Introduction -

Chapter First. — Simple Sensations - - Definitions — Excitations of Sense Nervous Action

Sensation Proper - - -

Correspondence between the Irritation and Sensation ------

Duration of Sensation - Intensity of Sensory Stimuli

Weber's Law

Increments in Intensity - - Periodicity of Sensory Stimuli Subjective Sensation -------

Complexity of Organs of Sense Subjectivity or Objectivity of Sensations -

cond. — The Process of Conception

Concepts distinguished from Sensations

Unconscious Concepts ... -

Memory - -

Vividness of Concepts -

Contents of Conception -

The Power of Concepts - - - -

Section 11.

Section 12.

Chapter S:

5 5

■7

10 11 13 14 16 17 19 20

22 22 23 24 26 26

VI

TABLE OF CONTENTS.

PAGE.

9.7

Section 7. Association of Concepts -

Section 1. Position ------- 82 Omnipresence ------ 82

Physical Analogies Applied to the Operation of Psychical Forces 83 Section 4. Soul Centers in the Brain - - - - 84

Section 5. A Fallacious Notion of Position - - 84 Section 6. The Soul and the Brain - - - .86

Section 7. Partial Truth of Materialism - - . 86

Chapter Fourth. — The Relation of the Soul to Time - 88

Section 1. Immortality ------

Section 2. Substance as Explaining Existence - Section 3. Essential Unity of Nature and the Conditioning Power of the Absolute - Section 4. Source of Permanency in Nature. (Figure omitted) -------

Section 5. Birth of the Soul -

Chapter Seventh. — The Realm of Souls o. Sects >n

PAGE.

- 106 107

- 108 109

Animal and Plant Souls - - - - 114 Diversity of Souls - - - - -115 Humanity Distinguished by Understanding 110 Humanity Distinguished by Reason - - 117 Humanity Distinguished by Will - - 118 Freedom of the Will - - - - - 119

PART THIRD. THE STRUCTURE OF THE BRAIN. Structure of the Brain

Section 1. Cells as Unit i of Structure - - - -125 Section 2. Origin of Cells - - 126 Section 3. Three Stages of Growth and Three Primitive Germ Layers - - - - 126 Section 4. Nerve Cells and Nerves - - - - 127 Section 5. Motory and Sensory Nerves - - - 128 Section 6. Chemical Constituents - ■ T 130 Section 7. Form and Development of the Central

Portion of the Nervous System - - 132

Section 8. Connection Between the Brain and other

parts of the Nervous System - - - 138

Section 9. Physiology of the Brain - - - - 141

Section 10. Development of Sensory Functions - - 143

Introduction

Sensations, conceptions, feelings, and acts of will constitute the group of familiar facts which we are accustomed to designate, although with a reservation in view of future discoveries, as the life of a peculiar being — the soul.

In order to fully meet our scientific requirements it is necessary, first, through the agency of observation, to completely set forth all the individual elements of this life and the general formulas for their combination — Descriptive or Empirical Psychology; secondly, to specify the nature of the subject in which this life subsists as well as those active forces and conditions by which this life is produced and caused to maintain that course with which experience has made us familiar — Explanatory or Metaphysical Psychology ; finally, to give a rational explanation why all these facts exist, or, in general, the mission of soul-life in the world — Ideal or Speculative Psychology. Now since the latter problem does not admit of a solution in strict scientific form, while the treatment of the first is easily combined with that of the second, the question with which we are chiefly concerned is this: u Under what conditions and

INTKODUCTION.

by means of what forces are the single processes of spiritual life produced; how are they united with, and modified by each other so as to produce, through their combined activity, the total of spiritual life."

Our course is that offered by the phenomena themselves, that is, we begin with external impressions, by which the spiritual activity is excited from moment to moment afresh, then consider the manifold internal transformations which these impressions undergo, lastly the reflex activities — motions or other acts — which result from them.

Only after the enumera'ion of these individual elements of the spiritual life is it possible to pass to a comprehensive consideration of the nature of that subject which controls this life.

Chapter First. Simple Sensations

§1. We here understand by simple sensations those which evince no combination of similar or dis-similar parts, and we, furthermore, assume them to be induced (as is usually the case) by external impressions.

In this case we distinguish in the production of a sensation, as the first process, the external sense excitement. No object becomes, by virtue of its existence simply ; an object of apprehension; it becomes such only as it either itself approaches to contact with our body, as in the case of impact, or communicates to the surrounding medium motions which extend from element to element until at length they reach our body, as is the case with sound and light waves.

In all cases, however, the external sensory stimulus is a motion of some sort or other and has no similarity to the mental processes which are evoked by it.

§2. The second essential is that process within the body which is caused by the external excitement. By their contact with the body these external irritants produce manifold changes in the external layers, of which we know little, and which we do not need to follow

OUTLINES OF PSYCHOLOGY.

psychologically because they can only become the sources of sensation when they reach the ends of the nerves distributed throughout the body. In them an excitement is produced which must extend through the entire length of the nerve-thread to the brain before a sensation can be produced.

An injury of the nerve, which prevents this transmission, results in the complete loss to consciousness of knowledge of the irritations in the peripheral nerve termini.

In what that excitement known as the nervous action consists is not definitely ascertained, but it is only important in psychology to answer the question whether this is simply a sort of physical motion or whether it already participates in the character of psychical life.

Sensation does not simply exist at large in the nerves but we must explain just what it is that is affected by the sensation. The nerve as a whole it cannot be, for the nerve is an aggregate of many parts and, moreover, is never, as a whole, in a state of excitement but, on the contrary, one part is affected after another successively.

It would therefore be necessary to assume that each indivisible atom of the nerve is a sensitive subject and each transmits its sensation to its neighbor until at last it reaches the soul.

The fact that the transmission of the excitement may be prevented by alterations in the physical continuity of the nerve, as, for example, by incision, shows that

OUTLINES OF PSYCHOLOGY.

this transmission is the result, not of an immediate sympathy, but of a physical effect produced upon one nerve atom by another.

Then we must suppose that the atom a acts physically upon the atom b and, as a result of this action, b enters the state of sensation E. Then atom b imparts a physical impulse to atom c which thus, in turn, becomes affected by the sensation E, The last nerve atom z acts then, in a way entirely unknown, upon the soul and now this also is so excited as to produce its sensation E,

It is easy to see that this last impulse, by means of which our sensation (which is, after all, the only thing of which we really know anything) is produced, would have exactly the same result if the nerve atoms exerted simply a physical influence upon each other and if their own sensations (which are simply assumptions and not discovered facts) did not exist at all. Since the idea of sensation in the nerves themselves contributes nothing to the explanation of our own sensations, and, moreover is not demonstrable, while the passage of a physical impulse can not be denied, we shall, in the future, consider the nervous action as simply physical motion which passes from one nerve element to another and which does not partake of the psychical nature characteristic of the resulting sensation.

§3. The third link in this chain of processes is that

OUTLINES OF PSYCHOLOGY.

condition of consciousness so familiar to all, the sensation itself — the act of seeing a light of a definite color or the hearing of a sound, for example.

Of the two elements in this process which we are able to distinguish in our thinking, namely the qualitative content, which we perceive, and the perceiving activity by which it is made known to us, neither the one or the other is comparable with the nature of the external excitement or the nerve process. As accurately as we may analyze the nature of ether waves we never discover in them the reason why they are seen as light rather than heard as sound, nor why one sort is perceiyed as red and another as blue and not the reverse. Furthermore, however we may combine the physical motions of nerve atoms there never comes a point where it is clear that the motion last produced is not to remain motion but must pass over into the entirely different process of sensation.

Vain are all attempts to discover how it is that the simple physical motion gradually passes over into sensation. We must, the rather, be content to state that nature has, by one of its imposed necessities, quite unknown to us, so correllated these two dissimilar series of processes — motions and sensations — (which we are unable to derive the one from the other) that a member of the one series always produces a definite member of the other.

§4. It would be assumed that these two series of processes would not be linked together without system, but rather that similar excitements in one series would correspond to similar sensations in the other and different excitements to different sensations. And, when, in the series of stimuli, a definite progress, retardation, periodicity, or prominent elements occur it would be expected that, in some way, all these would find expression in the corresponding series of sensations.

This assumption is but partially supported by experience. In the first place, the various classes of sensations ('colors, sounds, odors) occur serially one after the other, forming no complete system. It does not in the least follow because we perceive ether waves as light that we must perceive air waves as sound. The same is true of the individual elements of the different classes. He whose experience of taste and sight was limited to the taste sour and the color yellow would not be led to suspect the existence of bitter and blue.

Again, it is only in the case of sounds that we find a definite progression in the series of excitements corresponding to a similar progressive arrangement of the series of sensations; the pitch of sounds increasing with the rapidity of the vibrations of the sound waves. It should here be noticed that the manner in which the sensations reflect the variation in the exciting cause is itself quite peculiar. The difference in pitch between two tones has no similarity to the difference between two numbers, but expresses an entirely peculiar increase of qualitative intensity which could not have been expected and of which we have no other illustration.

In like manner the remarkable instance of the doubling of the number of waves finds a peculiar expression in the octave, which is not perceived as the doubling of anything but as a remarkable combination of identity and dissimilarity between the tones unexemplified elsewhere.

On the other hand colors, although they correspond in their prismatic arrangement to a similarly increasing wave-rate, dm not at all arrange their impressions in a series of increasing intensity. This discrepancy results from the fact that we can only legitimately expect a correspondence between sensations and their immediate causes — the nerve-processes. The latter, however, we do not understand, and are forced to compare, in all cases, only the results of sensation with the external stimulus upon which, as we saw, they do not immediately depend.

Finally, since our sensations do not form a perfect system, it is possible that the realm of sensations is not exhausted by our senses but that other animal souls may exist with entirely different, although, of course, to us unknown, forms of sensation.

§5, The duration of sensation can be roughly compared, in general, to that of the nerve process which produces it. For we find, under ordinary circumstances, that it never continues longer than the duration of the external irritation, unless the latter leaves behind enduring effects without or within us, which themselves constitute the stimulus for new sensations.

Strictly speaking, however, an excitement of the nerve, once produced, cannot cease of itself but must be interrupted by active opposition. This is usually furnished during health by the continuous activity of the nutritive process, by means of which the normal and indifferent condition of the nerves is restored and they thus prepared to impartially receive new impressions.

Very generally, however, not only when the irritation is very severe but particularly in the case of the sense of sight, the process may not be rapid enough. Then we have continuous or sometimes periodical excitations corresponding to the well-known illusions, i. e., actual sensations, which, if active enough, prevent the sense from receiving new impressions. An example of this is furnished by the brilliant figures produced by looking at the sun.

§6. Every day experience, as, for example, observation of an approaching light or of an expiring sound, shows that we are, in general, very sensitive to small differences in the intensity of the stimuli of sense. They are, however, only perceived as more or less intense and the moment never conies when we can affirm, from the evidence furnished by the impression simply, that one light is half as bright or one sound half as loud as another.

This circumstance prevents us from finding, by the most direct method, the exact law governing the dependence of the sensation upon the intensity of the stimulus.

We can, indeed, easily arrange a series of irritations which admit of an accurate measurement of their various intensities but we can not, by means of the observation of the intensity of our own sensation corresponding to them, refer to each its value in numbers. We can not, therefore, derive from the comparison of these two sets of values the general law which suffices for all. We are, therefore, driven to the following circumlocution, depending on the fortunate circumstance that we are at least able to judge with a high degree of accuracy and certainty of the likeness of two sensations. According to the fundamental experiments of Ernst Heinrich Weber (article " Sense of touch and sensation " in R. Wagner's Dictionary of Physiology, vol. Ill, part 2. ) which have since been confirmed and extended by many others, two similar excitements, when they begin to vary, do not produce two evidently distinguishable (instead of identical) sensations until their intensities stand in a definite geometric ratio. This ratio remains the same for one and the same sense, within the limits, of course, of irritations so small as not to awaken the nerve and so violent as to disturb the function. On the other hand it is different for different senses, approaching about 3 : 4 for the hearing and simple feeling of pressure upon the skin; 15 : 16 for the latter when supplemented by muscular sensation in lifting; 100 : 101 for sensations of light.

§7. The dependence of our capacity for distinguishing impressions upon the ratio of the intensity of the irritation, which has been derived from observation, is embodied in Weber's Law.

It does not explain, however, in what way the ratio of the intensity of the irritation really prepares us to distinguish impressions.

It does not explain, namely, whether the variations in the intensity of the irritations produce a noticable difference in the intensity of sensations, these otherwise remaining the same, or whether they produce sensations qualitatively different, and which are in this way distinguished.

In itself, every sensation is a single indivisible act. To separate in thought as distinct elements the qualitative content and the intensity with which it is perceived is indubitably permissible in so far as the immediate impression, with regard to which we can alone decide, agrees with it. This is, for example, the case with sounds. Here we may really convince ourselves that a sound of definite pitch and timbre may become louder or fainter without altering its character on this account.

On the other hand, it is quite questionable if the sensation of a heavy pressure is the same as that of a lighter one, or if the taste of a concentrated acid is really the same taste as that of a more dilute acid of the same kind. Still more reluctant are we to consider the sensation of cold as simply that of a feebler heat. Both are, rather, opposite poles, although the agencies producing them are similar processes.

Finally, various intensities of light have really various colors; a less brilliant white is not simply pale white, but it has become gray, and this gray, as well as black, cannot be considered as simplv a feebler sensation of white. These points have been overlooked hitherto and not disposed of.

The following discussion depends upon the assumption, which, although unproven, may be correct, that sensations are distinguished because their intensities vary according to a definite scale.

§8. It must be first remembered that for each sense a certain small irritation is necessary before a sensation can result. Naturally, in order to explain this circumstance, which is not at all self-evident, a resistance of some sort must be assumed by reason of which a very small irritation is prevented from affecting the mind. Where this resistance is offered is not known.

It is farther assumed that the passage from complete identity or imperceptible difference in two impressions to a difference just distinguishable is always one and the same constant increment of the sensation (i. e., of the second impression as compared to the firsts and that the minuteness of the distinction, may, therefore, be employed as a scale for measuring the intensity of the sensation.

It may be inquired, how must the irritation increase so that the passage from one value of it to another may always produce a constant increment in the intensity of sensation. According to the experiments referred to the answ r er is this: In order that the intensity of the sensation may increase by a constant difference, i. e., in arithmetical ratio, the intensity of the irritation must be increased much more rapidly, i. e., in geometrical ratio; or, the relation of the first to the second is comparable to that of a logarithm to the number of which it is the logarithm; more simply expressed, sensation belongs to that class of activities which rise in intensity with greater difficulty the more intense the activity they are already exerting.

The following questions remain to answer: —

1. Why this peculiar relation occurs at all, and why the sensation and the irritation are not, the rather, directly proportional, which would seem more natural? None of the theories offered is satisfactory, but the most plausible assumption is that, in the transformation of the external irritation, something or other takes place which proceeds slower as the irritation increases.

2. But why is it that all impressions are not distinguished — that, for example, a weight 3 must increase to 4 in order to produce an additional sensation of pressure and none is produced by 3^, 3^, or 3§? Certain arrangements can be easily thought of by which this discontinuity in the series of sensations could be produced but it is not in the least known where or how in the body or soul such arrangements are situated.

Both these riddles are quite unsolved.,

(Comp. G. Th. Fechner, Elements of Psycho-physics, Leipzig, 1860.

G. E. Mueller, Foundation of Psycho-physics, Berlin, 1878.)

§9. It may, perhaps, be claimed that a state of rest or an entirely unvaried excitement is never the immediate occasion of sensation, but that the passage from one condition to another is always necessary. From this it would follow that sensations which may continue to us for a long time, for example, the seeing of a light or the hearing of a sound, must be based on series of single impulses with intervening pauses so that here also a frequent repetition of alterations between excitement and a state of rest would occur.

In the case of sensations of light and sound this can be proven. Here even every single flash of light and every shortest sound consists of a considerable number of discrete impulses which are transferred to the organs of sense. In the case of the other senses this evidence is wanting.

If it be said that all processes of stimulation which are to produce sensations must have the form of oscillations between two opposite conditions, it, at least, must not be understood that the sensation consists in the enumeration of these impulses. They can only be regarded simply as the actual conditions upon which the origin of sensation in an unknown way depends. In the content of sensation itself — in redness or warmth — we discover no motion whatever and still less the number of the oscillations by reason of which it becomes the cause of sensation.

§10. If an excitement a, which is ordinarily produced by the operation of an external irritant and which is followed by the sensation A , be exceptionally produced by an irritant arising within the body then the same sensation A will follow; this is called subjective sensation.

Common examples are the ringing in the ear, flashes of light in the eye, and fever chills and heat.

In connection with this stands the theory of the specific energy of the nerve according to which each individual sensory nerve always produces the same sensation however it may be irritated. If it were so, it would not be strange, for every connected system of parts which is disturbed but not destroyed reacts in attempts to regain its equilibrium, the form of which re-action, depending upon its own structure and its inherent active forces, is not altered by the diversity of the disturbing irritants. But, in that case, since this attempt in one nerve is distinguishable from that in every other, each nerve must have its own peculiar structure, a condition which we have not, as yet, discovered.

There are no facts, however, which require to be thus explained. We simply know that light stimuli, blows, pressure and the passage of electrical currents through the eye waken sensations of light, and, perhaps, that blows and electricity produce sensations of sound, and the latter of taste.

Now a motion of the ponderable portion of the elasticglobe of the eye can hardly take place as the result of a blow without its being followed by a translation of a part of it into motions of the ether within it, thus producing light waves which would constitute as sufficient an irritant to affect the optic nerve as if they came from without.

In like manner, a blow may impart to tense membranes and orgcins vibrations which then constitute normal stimuli to the auditory nerve equally with sound waves from without.

Finally, the electric current produces certain chemical decompositions of the fluids of the mouth in which are to be found sufficient irritants to affect the gustatory nerve.

Hence it may be maintained that in order that the nerve should reach the condition a which is followed by the sensation A a definite adequate irritation is necessary, but very many inadequate irritants exist which subdivide in tneir operation into various components^ one of which may be an irritant adequate to produce the sensation A, others being perceived at the same time in other sensations, as, for example, the simultaneous feeling of pain in case of a blow.

§11. The operation of the external irritation is not as simple as formerly supposed; waves of light not acting, for example, directly upon the optic nerves to awaken according to their constitution all possible color and light sensations. There are found in the eye peculiarly constructed layers, as yet not well understood (rod and spindle layers) which appear to be designed to translate the light waves entering them into chemical changes in a peculiar substance (optic-purple) which then act as irritants upon the optic nerve. In the skin and tongue we likewise find peculiar tactile and gustatory organs, which, in some unknown way ; are supposed to give to the irritation the definite character necessary to affect the nerves contained in them.

In the ear we find something analogous, although here the simpler arrangement seems to prevail, each single nerve-fibre being receptive only to a single tone. The entire expanse of the fibres (in the organ of Corti)

is thus like a piano and each thread receptive to only one rate of vibration.

A similar hypothesis is in vogue as to the eye. According to this theory there are three sorts of threads, of which each is irritated independently, and each is sensitive to one of the three fundamental colors — green, red, and violet. The other colors result from the simultaneous irritation of threads of the other sorts.

This hypothesis is not invented gratuitously, but to account for the phenomena of color-blindness which are explained by it.

It is necessary to explain, however, why a definite combination of simultaneous excitements can produce from red, green and violet, the other colors, as yellow, blue, and red, which, so far as the impressions of sensation are concerned, seem not at all likely to be derived from them.

§12. In one sense, all sensations are but subjective, i. e.. only appearances in our consciousness which have nothing corresponding to them in the external world. Even in antiquity this truth was outlined, and modern physics fills out the picture. The external world is neither silent nor loud, neither bright uor dark, but is as utterly incomparable to these as is sweetness to a line. Nothing is happening outside of our bodies but motions of various sorts.

Physiology often makes the untenable statement that sensations are simply apprehensions of our own condition. All that goes on in the nerves while we are seeing is not in the least perceived by ns, and there is known no process in our souls preceding the sensation so intimately that it may be called an act of perception of the sensation. It may be said, therefore, that sensations are appearances within us which are, indeed, the results of external irritations, but are not strictly representations of them.

The proofs upon which this theory rests, all, admit of evasion. It may be still assumed that things are realty red or sweet, but we cannot know them to be so except as they cause motions to operate upon us which certainly are neither red nor sweet, but cause to arise in our minds the same redness and sweetness, as sensations, that really are peculiarities of things. The real proof is that such objective peculiarities are unthinkable- Wherein consists the brightness of a light which no one ever saw, or the sound of a tone no one has heard is quite as impossible to say, as what a toothache would be which no one ever had.