Outlines of psychology

Front matter

LOTZE'S

OUTLINES OF PHILOSOPHY

IV PSYCHOLOGY

Introduction

§ l. Sensations, ideas, feelings, and acts of will, constitute the well-known facts, the whole of which we are accustomed to designate, although with the proviso of future proof, as the life of a peculiar entity, called ' the Soul.'

The requirements of science would be perfectly satisfied, —

(i) in case we could, as exact observation directs us, furnish a complete exhibition of all the single elements of this life and of the general forms in which a they are combined {Descriptive or Empirical Psychology) ; —

(2) in case we could tell the nature of the subject of this entire life, as well as the efficient forces and conditions by which it is produced and compelled to keep within those forms of its course that are known empirically {Explanatory, Mechanical or Metaphysical Psychology) * and, finally, —

(3) in case we could specify what is the rational meaning for which all this exists, or the vocation which the life of the soul in general has to fulfil

OUTLINES OF PSYCHOLOGY.

in the totality of the world {Ideal or Speculative Psychology).

Since the last of the foregoing problems does not admit of a solution in strictly scientific form, and the treatment of the first may conveniently be combined with that of the second, the essential question with which we are to be occupied is the following : Under what conditions, and by means of what forces, do the individual processes of the spiritual life originate ; and how do they combine with and modify each other, and by such cooperation bring to pass the whole of the spiritual life ?

We choose our way, however, so as to follow the course of the thing itself; that is to say, we speak first of the external impressions by which the spiritual activity is at every moment aroused anew, then of the manifold internal elaboration which these impressions undergo, finally of the reflex activities, motions, and other actions, which result from them. It is only after passing in review these single elements of the spiritual life that it is possible to give a comprehensive exposition of the interior nature of the subject which leads this life.

Chapter I. Of Simple Sensations

§ 2. By ' simple sensations ' we understand, in this place, those in whose content no composite structure out of parts, whether dissimilar or similar, is to be observed : and we further conceive of such sensations — for so the case customarily is — as induced by external impressions.

In such a case we distinguish, as the primary process in the originating of sensations, the external sense-stimulus. Nothing becomes an object of perception by means of its bare existence : everything becomes such only by being either itself brought near to the point of contact with our body, as is the case of impact ; or else by imparting to a medium, which surrounds it, certain motions that are transplanted from element to element in this medium, and that finally reach our body, — as is

OUTLINES OF PSYCHOLOGY.

the case with waves of sound and light. In all cases, however, such external sense-stimulus consists in some form or other of the motion of certain masses of matter : and it possesses in itself no similarity to the spiritual processes that are to result from it.

§ 3. The second process which is necessary is that within the body which the external stimulus excites.

On its entrance into the superficial parts of our body, the external stimulus produces manifold changes in the most external layers of its covering, — changes of which we know little, and which we do not need to investigate from the psychological point of view. For none of them become the occasions of sensations until they reach the ends of the nervefibres that are distributed everywhere throughout the body, and produce in these fibres an excitation which must be propagated along the entire course of the nerve-thread up to the brain, if a sensation is to originate. Every injury to the nerve which prevents suqji propagation of the impulse has, therefore, also the effect of rendering all stimulation of the peripheral nerve-ending completely inoperative so far as consciousness is concerned. Now we do not know with definiteness in what the aforesaid excitation, the so-called 'nerve-process,' consists; and.it is of

THE SUBJECT OF SENSATION.

importance for psychology merely to inquire, whether this process is simply a process of physical motion, or whether it from the beginning participates in the character of the spiritual life.

Now a sensation cannot exist in the nerve in a merely general form, but it must be accurately specified precisely who is to have the sensation. The nerve as a whole cannot be this subject ; because the nerve is an aggregate of many parts, and besides, it is by no means all at one time in the condition of excitation. On the contrary, one part after the other is affected in succession. Nothing more, therefore, could possibly be asserted than that each indivisible atom of the nerve is a ' sensitive subject,' and imparts its own sensation to its neighbor until finally it arrives. at the soul.

Since, however, this propagation of the excitation can be prevented by altering the physical continuity of the nerve — for example, by section of it — it is also undoubtedly not the result of an immediate sympathy, but of a physical influence which one nerve-atom a exercises upon the next atom b, etc. We should accordingly be compelled to say : The atom a acts physically upon b ; in consequence of its suffering this influence, b is thrown into a state of sensation S ; and, again, in consequence of that, b exerts a new physical impact upon c, which in turn

OUTLINES OF PSYCHOLOGY.

is by this means induced to the sensation S and in consequence thereof to the exercise of a physical impact upon the atom d. The last nerve-atom z would then act, in a manner as yet quite obscure, upon the soul, and stir this, too, to produce its sensation S.

Now it is obvious that this' last impact by means of which our sensation (the only one of which we actually know anything) originates in us, will have had its result quite as truly if the nerve-atoms should exercise merely a physical influence upon each other, and if sensations of their own (which are merely empty conjectures and not demonstrated facts) should be wholly dispensed with.

Since, therefore, these sensations peculiar to the nerves contribute nothing whatever to the explanation of our own sensation, and besides are not demonstrable, while the propagation of a physical impact cannot be denied ; we shall in future consider the nerve-process also as merely a process of physical motion, that is carried over from one particle of the nerve to another, and as yet has nothing of the psychical character which belongs to the sensation that follows it.

§ 4. The third member of this chain of processes is, now, the state of consciousness so well known to us all, the sensation itself, — the * seeing '

TWO ELEMENTS OF SENSATION.

of a light of definite color or the ' hearing ' of a sound.

Of the two elements in the latter process which we can distinguish in our thinking, — namely, the qualitative content of which we have an experience in sensation and the activity in sensation by means of which we are conscious of this content, — neither the one nor the other is comparable with the nature of the external stimulus or of the neural process. However accurately, too, we may analyze the nature of the waves of ether, we never discover in it a reason why it must be seen as brightness and not rather heard as sound; and just as little, why some waves must be experienced as the sensation red, and others as the sensation blue, — and not the reverse. Further : however we may combine physical motions of nerve-atoms with one another, there never comes a point at which it would be comprehensible as a matter of course, that the motion last produced is bound to remain motion no longer, and must rather pass over into this process of sensation so totally different in kind.

All efforts to demonstrate how it comes about that the merely physical motion gradually passes over into sensation are, therefore, wholly in vain. We must rather be satisfied with asserting that a necessity of nature, which has hitherto wholly escaped our knowledge, has in fact united these two series

IO OUTLINES OF PSYCHOLOGY.

of processes, — the motions and the sensations, — incomparable and irreducible to each other as the two are ; and has done this in such a way that a definite member of the one series always has for its consequent a definite member of the other.

§ 5. It is now, however, to be assumed that these two series of processes will not be concatenated wholly without some controlling principle ; that rather similar sensations will correspond to similar stimuli, and different sensations to different stimuli ; and that in cases where a definite increase, interference, periodicity, or prominent point exists in the series of stimuli, all these will find expression in some way or other in the series of sensations also.

Empirically we are able as yet to establish the foregoing conjecture to only a very limited extent.

In the first place, the various classes of sensations (colors, tones, smells) exist" without intervening terms and as a bare matter of fact, side by side with each other ; and they do not constitute a closed system. For example, from the fact that we experience waves of ether as light, it does not in the least degree follow that we must consequently experience waves of air as sound.

The same thing is true of the single members of the particular classes. He who had merely had the

DISSIMILARITY OF SENSATIONS. I I

sensation of 'sour' or of 'yellow/ would not thereby be led to the thought that there must be also 'bitter' and ' blue.'

Further, that a definite increase in the sensations corresponds to a definite increase in the series of stimuli we observe to be true only in the case of tones, the pitch of which rises with the number of the vibrations of the acoustic waves. On this matter it deserves to be remarked, that the manner in which the sensation renders these differences of the stimuli is quite peculiar to itself. The difference in pitch between two tones has no similarity at all to the difference of two numbers, but expresses an altogether peculiar increment of qualitative intensity, which by no means admits of being divined beforehand, and of which we have elsewhere no example. Just so the distinguished instance of a doubling of the number of waves finds an expression peculiar to it, in the octave, which is not experienced in sensation as a doubling of anything whatever, but as a noteworthy and otherwise unexampled combination of the identity and difference of both tones. Colors, on the contrary, although in their prismatic arrangement they originate from a similar ascending scale of the number of waves, do not by any means arrange themselves for the immediate impression into a series of increasing pitch. This is dependent on the fact, that we can rightly expect a proportionality to exist only between the sensations and the neural processes as their proximate conditions. But we have no acquaintance with these latter ; and on this account we compare, without reaching any comprehensive result, the sensations with the external stimuli on which they do not immediately depend.

Finally, since our sensations do not constitute a closed system, the thought is possible that the realm of the sensible is not exhausted by our senses ; on the contrary, that there are other animal souls, with kinds of sensation quite different and yet — as is natural — wholly unknown to us.

§ 6. The duration of sensation can be compared as a gross magnitude with the duration of the neural process which excited it. For we find that under ordinary circumstances it is never longer than the duration of the external stimulus, unless this latter leaves behind permanent after-effects, either outside of or within us, which themselves ^n turn become stimuli for new sensations.

Strictly taken, an excitation of the nerve which has once originated can never cease of itself, but must be annulled by efficient counteracting forces. This customarily takes place ; and, when the vitality is sound, it takes place by means of the ceaseless

ENDURING EFFECTS OF STIMULI. 1 3

activity of the whole process of metabolism, by which constantly the nerve's normal condition of equilibrium is re-established, and thus rendered capable of an impartial reception of new impressions.

Such recovery, however, fails to take place with sufficient speed, not merely when the stimuli are of very great strength, but particularly in the sense of sight as a rule ; and, in such a case, the well-known after-images correspond to the excitation which still continues to be kept up, and which sometimes even undergoes again a periodical increase. By ' after-images ' is meant actual sensations which, if they are lively enough, make the organ of sense incapable of the reception of new impressions ; — as, for example, the dazzling images which follow looking at the sun.

§ 7. Certain experiences of every-day occurrence — for example, the observation of a light approaching, or of a tone dying away — prove that we are in general very sensitive to minute differences in the intensity of the stimuli of sense. But this remains a mere matter of degree, greater or less ; and the moment never comes when we could say that according to the measure afforded by immediate impression, one light is half as bright, or one tone twice as loud, as another.

The above-mentioned circumstance prevents us from discovering in the shortest way the exact law in accordance with which the sensation depends on the strength of the stimulus. It is true that we can easily establish a series of stimuli whose different intensities admit of accurate measurement ; but we are unable to assign to each of these values, on the ground of introspection, the strength of the sensation that belongs to it, in numerical terms ; and, therefore, we are also unable to discover, from a comparison of these two sets of values, the universal law which satisfies them all. We are therefore compelled to employ the following circuitous method.

That is to say, it happens sometimes, although rarely, that we are uncertain whether two impressions, a and p, are at all different and not rather of equal intensity. Now since in any case, in order that they may appear different at all, the stimulus which forms the basis of one must be greater or less than the stimulus to which the other corresponds, the question may be raised in the ne^xt place : How large must be the difference between two stimuli (a and !>) of the same kind, in order that the two sensations (a and p) corresponding to them may appear ' just observably different ' ? and further : Is this difference of the stimuli (b-a), which is the necessary condition of such transition from the sim-

THE LAW OF WEBER. 1 5

ilarity of the sensations to the 'just observable difference ' in their intensity, always the same, or does it alter with the increase of the absolute magnitude of the stimulus ?

• According to the fundamental investigations of Ernst Heinrich Weber, which have since been confirmed and extended by many others, two sensations are distinguished as two only in case the intensities of both the stimuli which occasion them stand in a definite geometrical relation. In other words : To a certain stimulus a, in order that the sensation a, first excited by it, may pass over into a sensation p, whose difference from the former is just observable, there must be joined an increment x which is so much the greater, the greater a itself already is.

This relation which a and b (or, respectively, a and x) must sustain to the result in question, remains the same for the sensations of one and the same sense ; but, of course, only within the limits between stimuli of too small intensity, which do not excite the nerve, and those of too great intensity, which disturb its function. On the contrary, it is different for different senses : — approximately about 3 : 4 for hearing and for mere sensations of pressure on the skin ; 15 : 16 for the latter, in case they are supplemented (when the weights are lifted) by muscular feeling ; 100 : 101 for sensations of light.

§ 8. This dependence of our capacity for making distinctions upon the relation, in respect of magnitudes, of the stimuli, which has been directly derived from the observations, forms the content of the so-called " Law of Weber."

In all the foregoing the question remains as yet wholly undecided, in what way precisely this relation in the magnitudes of the stimuli makes us capable of distinguishing the resulting impressions : that is to say, whether it is due to the fact that stimuli of different intensity produce an observably different intensity of the sensation, while its kind remains wholly unchanged ; or whether it is due to the fact that different ' intensities ' of the same stimulus beget qualitatively different sensations, which are then separated by us just according to their differences of quality.

In itself considered, every sensation is a single indivisible act. Now it is undoubtedly permissible for us to separate in thought, as two constituent parts of this act, the qualitative content and the intensity with which this content is experienced ; — this, so far as the immediate impression, which alone can decide the point, accords therewith. Such is, for example, the case with tones. Here we may actually convince ourselves that a tone of definite pitch and color of ' clans: ' can sound louder or weaker

DISCUSSION OF WEBER S LAW. 1 7

without, on that account, altering its nature. On the contrary, it is very questionable whether the sensation of a pressure of greater intensity is really the same sensation as that of a smaller intensity, except that the former is stronger than the latter ; further, whether the taste of a concentrated acid is really the same taste as that of the dilute acid. Much more repugnant still is immediate feeling toward our considering cold as merely a weaker intensity of heat. Both are rather at opposite poles, although the causes of their production are similar processes. Finally, different intensities of light actually have likewise different shades of colors ; a white of a less intensity of brightness is not merely so, but it has become a gray, and this gray, as well as the black, which is the last result, cannot possibly be regarded as merely a feebler sensation of the white.

The foregoing considerations have hitherto not been sufficiently regarded ; and neither have they been refuted. What further is now to be adduced depends upon an assumption which is perhaps correct but which is unproved : namely, that sensations become distinguishable because their intensities vary according to a fixed standard.

§ 9. We have, then, in the first place, to recognize the truth that there must be a certain small magnitude of stimulus for each sense, below which it cannot fall if any sensation whatever is to originate. Naturally enough, some resistance, by which the stimuli of too small intensity are kept from an influ\ ence on the soul, is assumed in order to explain the above-mentioned circumstance, which is by no means a matter of course. But where such resistance is achieved, as it were, is not known.

It is further assumed, that the transition from complete likeness or unobservable difference between two impressions to a difference just observable is always one and the same constant increment of the intensity of the sensation (that is, of the second impression compared with that of the first); and, accordingly, the fineness of the distinctions may be employed as a measure for the intensity of the sensations.

The question may then be asked : How must the stimuli increase, in order that the transition from one of its values to another may invariably result in the same constant increment of the intensity of the sensation ?

According to the investigations already referred to, the foregoing question is answered as follows : If the intensities of the sensation are to increase by a constant difference, and therefore in an arithmetical series, the intensities of the stimuli must be aug-

DISCUSSION OF WEBER S LAW. 19

mented much more rapidly, that is, in a geometrical series. Or — what is the same thing — the relation of the first to the second is comparable to the relation of a logarithm to the number of which it is the logarithm. More simply expressed ; the sensation belongs to those achievements or activities which are always to be raised to a higher degree with the more difficulty the greater the intensity with which they are already in exercise.

The following questions, however, still remain to be answered : —

(1) Why does this peculiar relation take place at all ; and why does not the sensation rather (a thing which would be much more natural) increase as a simple proportional of the stimulus ? None of the theories proposed on this point is satisfactory ; but still the most probable is the assumption that, in the transformation of the external stimulus into excitations of the nerves, something or other occurs which causes the latter to augment much more slowly than the external stimuli increase.

(2) But how does it come about that, while the stimulus constantly augments in intensity, the intensity of the sensation increases not merely in a much smaller degree but also only discontinuously ? Why are not, as a rule, all the impressions distinguished as different ? How does it come about that, for example, a weight 3 must increase to at least -t in

order to gave a now sensation of pressure ; that, on the contrary, it gives no such sensation, if it is only 3J, 3}, 3| ? Something in itself impossible is involved in the thought that a force which increases constantly should, nevertheless, furnish the occasion for a second kind of action only by sudden increments or discontinuously ; and if not thus, then not at all. There are, then, doubtless contrivances conceivable, by means of which this discontinuitv of the sensation could be produced. But we have not the least information as to where or how, in the body or in the soul, such contrivances do in fact exist.

Both these riddles are therefore wholly unsolved.

§ 10. It may perhaps be asserted that a state of rest, or an excitation maintained with complete uniformity, is never the proximate condition of a sensation ; but that such condition is always nothing but the transition from one state to another.

It would follow from the foregoing that sensations, such as we might have last during a considerable time, — for example, the seeing of a light or the hearing f atone, — must depend on certain series of single impulses with intervening pauses ; so that in this case also a frequent repetition of the

CHANGE NECESSARY TO SENSATION. 21

alternation between excitation and non-excitation would take place. For sensations of light and sound this admits of being established by proof. In these cases, to be sure, every single flash of light, or every tone however brief, depends upon a considerable number of such discrete impulses which are carried to the organ of sense. As to the rest of the senses we lack information.

Now if the above-mentioned fact is expressed as follows, — that all processes of excitation which are to lead to sensations must have this form of oscillation between two opposite states, — then we must at least not add the statement that the sensation itself consists in the recounting, as it were, of these single impulses. In these impulses we can never see anything but the matter-of-fact condition to which the originating of the sensation is attached in an incomprehensible way. For in the content of the sensation itself, in the red or the warm, we perceive nothing of motions whatever ; and still less of the number of their oscillations, by means of which they become the causes of sensation.

§ 11. If the same excitation a, which is customarily effected in a nerve by an external stimulus, and upon which the sensation a follows, is exceptionally produced by a stimulus originated in the interior of the body ; then the same sensation a follows as well. In such a case the sensation is called subjective. Common examples are ringing in the ears, flashes of light before the eyes, the chill and flush of fever.

In connection with this, the so-called principle of the "Specific Energy of the Nerves" has been laid down, according to which every individual nerve of sense, by whatsoever means it may have been excited, always produces the same sensation.

If the fact were such, it would not be very wonderful. For every coherent system of parts, which is disturbed but not destroyed, enters upon efforts at the re-establishment of its equilibrium, the form of which depends solely upon its own structure and upon the connection of the forces effective in it ; and such system is not altered according to the variety of the disturbing stimuli. But in order that these efforts in the one nerve may be distinguished from those in every other, each nerve must have its own special structure, — a master of which we as yet know nothing.

There are no facts, however, such as it is intended to explain in this way. We merely know that the stimulus of light, impact and pressure, the passage of a current of electricity through the eye, awaken the sensation of light ; and perhaps that impact and electricity produce also the sensation

SPECIFIC STIMULI OF SENSE. 2$

of sound ; and the latter also the sensation of taste. Now a motion of the ponderable parts by means of impact can scarcely take place in the tense eye-ball without a part of this motion being also converted into motions of the ether that exists in the eye, and so producing a motion of light, which acts as adequate stimulus upon the nerve of sight in precisely the same way as if it came from without. Just so the imparted shocks may be changed into oscillations of the tense parts and membranes, which are then normal stimuli for the nerve of hearing just as well as are the acoustic waves that come from without. Finally, it is quite certain that the electrical current excites chemical decomposition of the fluids of the mouth, and that the adequate stimulus for the nerve of taste consists in this directly. It is still possible to make the following assertion : In order that a nerve may be thrown into the state a, upon which the sensation a follows, a definite adequate stimulus is always necessary ; but very many inadequate stimuli, in case of their being of influence, divide into different components : one of these components is then the adequate stimulus which is the condition of the sensation a; and the others become objects of perception through other sensations (for example, the pain contemporaneous with the impact).

§ 12. The influence of the external stimuli does

not take place in so simple a manner .is was formerly supposed; in such manner, for example, that the waves of light immediately as such act upon the nerve of sight and, in accordance with their nature, awaken all possible sensations of color and light. Instead of this we find in the eye certain layers of a peculiar, and still in many respects mysterious, structure (layers of rods and cones), which seem designed to transform the motion of light that reaches them into a chemical alteration of a special substance (visual purple) which, in turn, acts as the primary stimulus upon the nerve of sight. Just so do we find in the skin, and in the tongue, peculiarly constructed corpuscles of touch and corpuscles of taste, which first give to the stimulus, in a manner as yet unknown, the form in which it is to act upon the nerves contained in them.

In the organ of hearing we do not know hi anything similar. For its purpose, however, another form of contrivance seems to have been hit upon, so that each single nerve-fibre is susceptible only for a single tone. The entire expansion of the fibres (upon the organ of Corti) would therefore be comparable to the key-board of a piano, and each fibre accessible only to a definite rate of the vibration of the waves.

FUNDAMENTAL COLORS. 25

The phenomena of ' color-blindness ' have led to a similar hypothesis in relation to the eye. It is supposed that there are three species of fibres, each of which, when stimulated by itself alone, causes the sensation of one of the three fundamental colors, — green, red, and violet. From the synchronous excitation of the fibres of different species the other colors are then supposed to arise. This hypothesis is not invented gratuitously; but, as was just said, it has a reference to the facts of color-blindness, which it is designed to explain. The further demand, however, must not be made, — namely, to see into the reason why a definite mixture of synchronous excitations from red, green, and violet, causes the other colors, like blue and yellow, to originate ; when the latter, so far as the mere immediate impression of sensation is concerned, do not in the least degree appear deducible from the former.