The Fundamental Laws of Human Behavior
The generalizing function changing from a nervous and muscular into a purely nervous function. Relation between processes in the higher nerve centers and strictly subjective experiences. Nervous functions of generalization especially likely to have also the subjective aspect. For the generalizing nervous function in another person's brain we substitute an imaginary mental state. The nervous correlates of sensation and imagery. Associations of successive and of simultaneous mental states. Attention. Pleasantness and unpleasantness. Insufficiency of introspective psychology.
WE have discussed, in some detail, the biological significance of spoken and written language. We stated that practically no generalization is possible without speech. We showed that generalization, regarded as a biological function, comes about by the insertion of an additional link in the series of organic processes previously existing, and that the link added is a double link, a motor response, speaking, and a sensory excitation, the sounding word. One must, not conclude, however, that consequently in every process of generalization the subject must, actually speak the word upon which this generalization is based, that is, must innervate and move his speech organs. No doubt, generalization in general has its origin in actual speech. But the speech function in all generalizations tends to change during use from a nervous
( 228) and muscular function to a purely nervous function; and a highly educated individual may even originate generalizations without at all calling his speech organs into play.
Figure 54 helps us to understand the dropping out of the muscular function. The figure is a composite of Figures 59, and 53. In discussing the latter figures we showed that an excitation by any article of food of any one of the sensory points to the left (in Figure 54) may call forth a response at any one of the motor points to the right by mediation of Mw and Sw since the reaction at Mw, the organ of speech, results in a sound and thus in a physical stimulation of Sw, the ear.
In this way any article of food appearing before the eye or another sense organ tends to call forth any action of preparing for a meal and eating. Now, a glance at Figure 54 teaches that the generalization, as soon as established, no longer needs the peripheral points Sw and Mw, essential to its creation. A nervous excitation starting from Sa, Sb, Sc, or Sd can directly over S2abedw M2efghw take its path to Me, Mf, Mg, and Mh. The functional relation to the points Sw and Mw of this direct path is then merely historical, consisting in the fact that a part of the path from, say, Sa to Mh (namely, the part from the point
( 229) S2abcdw to the point M2efghw) has in the past been traveled over by nervous processes conking from Sw. A fact of this kind we shall soon find to be of a particular significance.
We have just seen that no actual speaking, nor writing either, is required for the functioning of a generalization once established. The biological function of generalization may be regarded as purely nervous. Moreover, it is a nervous process inevitably taking its path over higher —very high— nerve centers. Between nervous processes in the higher nerve centers and strictly subjective experiences, that is, the individual's states of consciousness, there is an important relation. We have good reason to believe that a mental state never occurs unless there is at the same time a nervous process taking its path through the higher nerve centers. It is probably not correct to call the relation between a mental state and a process in a higher nerve center causal, which would mean that the oil(, occurs first and the other after, or the other first and the one alter. More probably they are strictly simultaneous; but we are as yet unable to prove it because science has not yet invented all instrument by means of which we can observe I he process going on in our own brain while we have the mental state corresponding to it. If they are strictly simultaneous, we have the right, to describe them by saying that they are really only one phenomenon occurring in the world, but that this phenomenon has two aspects. In so far as it can be observed by any and all individuals, including the one whose brain is affected, who are in possession of the proper instruments (not yet invented), we call it an objective phenomenon, a nervous process. In so far as it is (and can be) known exclusively by the one individual whose brain is affected, we call it a subjective phenomenon, a mental state. We understand, then, that among all the possible nervous functions those
( 230) of generalization are especially likely to have also the second, the subjective aspect, because they occur in very high nerve centers.
This brings us back to the considerations with which we started out in the first lecture. We stated there that in pronouncing a moral judgment on a boy who has obstructed the track of a train, we seem to be interested chiefly in his thoughts, although only his actions, never his thoughts, can be known to us by observation. When in school, we seem to be interested chiefly in what our teacher thinks of us, although only his actions can be observed by us. The path is now open for our understanding this.
The proper valuation of the boy's or the teacher's action depends on the application of the proper generalization. It really does not matter much whether the boy placed a plank on the track by using his hands, or caused a rock to roll on the track by using his feet, or, by using his speech organs to pretend a different purpose, made a friend put a stick of dynamite there. What matters is only the fact that all these events are likely to cause the derailment of a car. The derailment, again, is not of so much importance for our judgment as the fact that the derailment may be the cause of many different events, the saving of a train from passing on a bridge with underwashed foundations, the killing and maiming of numerous passengers by the destruction of the car, and innumerable others. Our judgment, then, is impossible without generalization. It is itself a generalization of a high order. It expresses our decision as to what generalizing function determined the boy's motor activity, whether he said to himself (remember in Figure 54 the points Mw and Sw!): "I will save" or "I will kill."
As we found in the preceding lecture, however, it is not necessary that the boy actually pronounces the word. It leads to the same motor result if the particular generalizing function on which our judgment has decided, is purely nervous, a nervous process passing through a certain higher center in the boy's brain. Therefore, if our judgment were in every respect what it ought to be according to the standards of exact science, it would plainly express that this generalizing process occurred in this high center of the boy's nervous system. But, unfortunately, these nervous processes in the higher centers are only hypothetical, owing to the fact that the instruments for their observation have not yet been invented. That they will have been invented in a hundred years, or sooner, or later, does not help us. So we help ourselves by substituting in our imagination for the boy's nervous process which today the undeveloped state of physiology will not let us know, an assumed reality which we do not, shall not, cannot ever know, a mental state of the boy, his willing to save, or to kill. The right. to substitute this assumed mental state, in spite of its being forever unknowable, for the nervous process, which is insufficiently known only because of the insufficient development of scientific technic, we derive from the fact, that a (slightly familiar) nervous process like the boy's is in each of us, individually, regularly coexistent. with a, perfectly familiar state of willing to save or to kill.
In a similar way we substitute in our imagination for the nervous process determining our teacher's actions a mental state taken from the store-house of our subjective experiences. Objectively, scientifically, we know only our teacher's actions. We are not so much interested, however, in the particular act as in the class to which it belongs. We do not, for example, care so much whether he uses his writing hand or his talking mouth to praise us, as we care for the general fact that he
(232) praises us and does not blame us. It is, therefore, the generalizing nervous ,function in a high center of the teacher's brain that concerns us. And for this nervous function we substitute, for reasons stated, an imaginary mental state, imaginary since, not being ours, it is unknowable to us.
From this it must be clear that there can be little scientific progress in our knowledge of the interrelations between human beings until we shall be able to comprehend better the nervous processes of generalization which almost exclusively determine these interrelations, our social intercourse. But since we shall undoubtedly continue, for a long time to come, to substitute in our discussions of social events for the generalizing nervous processes imaginary mental states, it is important that we understand how in our individual life nervous processes and mental states are connected. We emphasized on page 2O9 that (in Figure 54) a part of the path of the generalizing function had in the past been traveled over by nervous processes coming from Sw. Let us note that stimulation of Sw is stimulation by a word, and let us remember the extraordinary part played in any generalizing function of our individual consciousness by word imagery. We draw the conclusion that our consciousness of the word-image, when any of the points Sa, Sb, Sc, or Sd in Figure 54 is stimulated and responded to by any of the points Me, Mf, Mg, or Mh, has its nervous correlate in the fact that a part of the nervous path taken by the excitation has previously been traveled over by a nervous excitation, coming from the sensory point SW corresponding to the particular nature of this word image (auditory, visual, etc.), while S«, remains at present unstimulated.
Thus we can at once establish a general rule concerning the nervous correlate of sensation, on the one hand, and of imagery, on the other. Sensation, we know from our individual experience, requires proper sensory stimulation, but requires also, we have good reason to believe, that the nervous excitation takes its path, not directly over a reflex arch, but over higher nerve centers; otherwise there is no consciousness. It is a common condition, then, for the existence of either sensation or imagery, that the nervous process does not remain in the lowest centers, but takes its path over higher nerve centers. The difference, whether our consciousness is a sensation or an image, depends on this : If the nerve center which is conducting a nervous excitation, is at present serving the sensory point corresponding to the mental state in question, that mental state is what we call a sensation; if the center has only in the past served the sensory point corresponding to the mental state in question, that mental state is what we call an image.
Introspective psychology, that is, the psychology which restricts its observations to (lure observing individual's) consciousness and attempts to comprehend human life by comprehending the one individual's life, has long ago formulated one important law, that of the association of mental states. An association may be one of successive or of simultaneous mental stales. In the former case, "association" means that the particular mental states tend to recur in the same order, or, more rarely, in reversed order. In the latter case, "association" means that the particular mental states tend to occur together at one moment rather than temporally separated from each other. Let us state, in the terms of nervous function employed in these lectures, the nervous correlate of the law of association.
A nervous process starting from a certain sensory point, say, Sa in Figure 16, terminates and is succeeded by another nervous process starting from Sb. This second process is then not uninfluenced by the first. A larger fraction of its flux takes its path over the connective neuron S2ab M2ab than would have done so if the other flux had not a moment ago been conducted partly by this neuron. (We have discussed this same fact in Lecture 10 with a somewhat different end in view, namely, in order to show that a nervous process can be more or less deflected not only by a simultaneous stronger one, but also by any directly preceding one.) When now, at any later time, Sa is stimulated again, more of the flux passes up from S1a to S2ab M2ab than the first time, since the resistance of the higher center S2ab M2ab , affected by two nervous processes, has been reduced relatively more than that of the lower center S1aM1a . If we represent by S1aM1a a relatively high center, (relative to the whole system), the flux in S1aM1a must be accompanied by consciousness. The nature of this consciousness is determined by the nature of the sensory excitation at Sa. The flux in the still higher neuron S2abM2ab is accompanied by the same consciousness, but also by the consciousness corresponding to the nature of the sensory excitation at Sb, because S2ab M2ab has been traveled over previously by a nervous process coming from Sb. It is clear that the mental state "b" must begin later than the mental state "a" since the relief of tension starting from Sa can not reach the point S2ab as soon as the point S1a. The successive association of the two mental states is therefore a simple consequence of our assumptions concerning the laws of nervous function.
What we have just said about two mental states of a successive association, holds equally for three, four, etc. Nothing new is to be found in these cases, except that, the
( 235) greater the number of different sensory excitations (for example, add Sc and Sd in Figure 16), the higher are the nerve centers coming, more or less, into play (up to S4abcd M4abcd in the same figure). This is evident enough. Another fact, however, deserves probably a brief discussion, that of reproduction of the mental states in the order opposite to the one in which they were acquired. The classic treatise of Ebbinghaus "On Memory" proves the existence also of a tendency for reproduction in the reversed order. The nervous correlate of this tendency is easily derived from the same example which we have just used. If Sb alone is stimulated, after the succession of stimulus "a" and stimulus "b" has had its opportunity for changing the relative resistances of the higher centers in Figure 16, the nervous excitation travels, not only over S1b M1b but also considerably over S2ab M2ab. The flux in the centers S1b M1b and S2ab M2ab is then accompanied by two mental states, "b" occurring first because the center S1b M1b can be reached from Sb in less time than S2ab M2ab . That is, the mental state "b" calls up the mental state "a" although in all the instances of twofold stimulation "b" was invariably preceded by "a."
Ebbinghaus rightly points out, however, that this reproduction of mental states in the order opposite to that of their acquisition by the individual is quite rare. He explains it by calling attention to the fact that, as a rule, the two mental states are members of a series and are followed by other mental states. In the alphabet, for example, "b" but rarely calls up "a," because its tendency to call up "c" is still greater. Let us explain the same fact in terms of nervous function by the aid of Figure 55. If in the mental process of memorizing the letters of the alphabet or any other series Sq is stimulated soon after a flux from Sp has occurred in the center S2pq M2pq , the part
( 236) of the flux which does not take its path from S1q to the right but upwards, must divide so that more passes in the direction of S2pq and over the center S2pqM2pq than in the direction of S2qr and over the center S2qrM2qr. We may say, then, that from any of the points S1a larger
flux travels up to the left than up to the right. This is indicated in Figure 55 by double and single lines. It is then immediately clear that during the memorizing any one of the neurons marked S2M2 receives from the right below a stronger flux than from the left below. For example, S2pqM2pq receives relatively a strong flux from Sq, a weak flux from Sp; and S2qrM2qr receives a strong flux from Sp, a weak flux from Sq. On some later occasion Sq alone is stimulated, say, for the sake of a test. The flux divides at S1q. A part travels over S1qM1q, another part over S2pqM2pq, a third over S2qrM2qr. Our problem is to show whether of the mental states other than "q, "namely "p" and "r," the one or the other has a higher degree of consciousness. Obviously, the degree of consciousness depends on the relative flux which has previously passed over the higher centers S2pqM2pq and S2qrM2qr from Sp
(237) and Sr. Above we found that the previous flux over the higher centers from Sr was relatively strong, from Sp, relatively weak. Accordingly, the mental state "q" tends to call up the associated mental state "r" rather than the associated state "p." Thus we have explained this rule of introspective psychology in terms of nervous function.
To explain in terms of nervous function the simultaneous association of mental states, it is only necessary to refer to our discussion of that kind of variation of the nervous path which we called motor condensation. If a number of sensory excitations unite in a higher center in order to pass into a common motor outlet, the condition for a simultaneous association of definite mental states is fulfilled. Whenever now, even from a single sensory point, a, nervous process travels over that center, the mental states corresponding to all those sensory excitations must simultaneously enter consciousness.
Aside from the time-honored law of association, only one other generally recognized law of mental life has been discovered by purely introspective psychology, the law of attention. By attention is meant. "he 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." It is plain that, in terms of nervous function,, this is the law of deflection of weaker nervous processes by a stronger one. The stronger nervous process determines the dominant aspect of the total mental slate. The weaker ones, if deflected from their own course before having reached any centers of a higher level, are not accompanied by any consciousness whatever. The higher the center reached by any of these nervous processes before it enters the path of the stronger process, the more pronounced, relatively, the corresponding consciousness; the greater,
( 238) obviously, also its chance of becoming later the prevailing nervous process itself and determining the animal's next action. Thus we must expect to find by introspection in our individual mind as a rule a single mental state dominant together with a large number of others of varying degrees of consciousness. The law of attention, which has caused introspective psychology so much discomfort, and which Herbart attempted in vain to clear up by his "mechanics of ideas," thus becomes clear enough as soon as we comprehend its nervous correlate.
Introspective psychology has long struggled to understand the relation between the feelings of pleasantness and unpleasantness (not meaning by the latter term "pain," which is a sensation) and human behavior. It seems advisable to approach the problem from another point of view, studying objective nervous functions, hypothetical as they may be for the present, rather than the introspections of the individual which by their very nature can never be anything but subjective. We can distinguish two classes of conflict between two nervous processes of which one originates while the other is still going on. Either, the first is stronger, deflects the second and by absorbing it grows still stronger. This corresponds to our experiences of pleasantness, for in all such experiences, however varied in other respects, we continue the same form of behavior more and more vigorously. Or, the second nervous process is stronger, weakens the first by deflection, and finally absorbs it completely. This corresponds to our experiences of unpleasantness, for in all such experiences our behavior suffers interference until it is completely replaced by another form of behavior, when the unpleasantness ceases. The nervous correlate of feeling may then be described in the following words. The nervous correlate of pleasantness and unpleasantness
( 239) is the increase or decrease of the intensity of a previously constant nervous process if the increase or decrease is caused by a force acting at a point other than the point of sensory stimulation. The condition of the second half of this sentence is necessary because our experiences of feeling do not depend on a change in the intensity of a stimulus, but on the interference of nervous processes in higher nerve centers.
Introspective psychology, disregarding behavior, for centuries has been satisfied with remarking that pleasant experiences are the experiences of helpful situations, unpleasant ones those of harmful situations,. This is true enough, for the animal body is so equipped by nature with nervous connections of sensory and motor points that reactions to a helpful situation continue and grow stronger, reactions to harmful situations are weakened until they discontinue. But there are exceptions to this rule which destroy its whole value for any mental or social science, for it is an undeniable fact that the pleasure-seeker may sacrifice his life to pleasure. Not, the study of the individual's consciousness, of "the structure of the mind," but the study of the nervous laws of behavior will enable us to understand the significance of human action for human life in the individual and in society. The scientific value of introspective psychology consists merely in the fact that it aids us in discovering the laws of nervous function.
How unreliable the results of introspective psychology are, can be learned, for example, from the attitude of
( 239) psychologists toward the question as to the relative importance of the kinesthetic sense. When, during the nineteenth century, sensory neuron endings were discovered in muscles and tendons, some psychologists made use of the new sense in order to explain numerous phenomena whose explanation had formerly been impossible.
Immediately they were opposed by others who asserted that the kinesthetic sense was of practically no significance since in their individual consciousness they could not, introspectively, discover any kinesthetic sensations or images at all. We saw in Lecture 13 that kinesthetic sensory activity is quite indispensable for the training of any temporally complex reaction, for example, speech. Introspective psychologists, however, are rarely among those people who—like mechanics, skilled factory workers, sportsmen, and athletes—acquire new habits of temporally complex reaction late in life. Their own habits of this kind were all acquired in early childhood and have long ago become completely automatic,—short-circuited, so to speak. Since the nervous processes of these reactions no longer pass over higher centers, there can then be little consciousness, especially no consciousness of kinesthetic sensation or imagery. It does not follow, however, that this consciousness was absent in their first few years of life when they received all the motor skill they possess; and it does not follow that the kinesthetic sense during any period of life is insignificant as a nervous function. This is, perhaps, the best example one can find of the failure of introspection in the explanation of human behavior.
Enormous is the amount of introspective research embodied in the publications belonging to the mental and social sciences from Aristotle to the present day, enormous the energy which has been spent on careful analysis of
( 241) introspective records by the application of generalizations, of abstractions. But if one attempts to collect results of these investigations which are generally recognized—or recognized at least by a majority of the scientists of the present day—as contributing toward an understanding of human life in the individual and in society, he is struck by the fact that there is almost nothing to be collected.
A few abstractions are recognized as valuable for the science of general psychology: memory, association, attention. In the special mental sciences, ethics, education, sociology, politics, political economy, little — aside from purely statistical facts — seems to be more than personal opinion. There appears to be only one hope that a real mental and social science, comparable to natural science, will ever come about, the hope based on the observation that just as far as the facts and laws of introspective psychology have hitherto been correlated with—replaced by—facts of behavior and its laws, has confusion and obscurity given place to order and clearness in the mental sciences. There is hope, then, that by future progress in our knowledge of the laws of human behavior more order and clearness will be there introduced.