Sensation, Imagination and Consciousness
John E. Boodin
Carleton College, Northfield, Minnesota
Our scientific concepts generally are in the melting-pot. They are all infected by relativity. This is as true in psychology and philosophy as in the physical sciences. In each case we must be willing to reconstruct our concepts on the basis of new evidence. Psychology has too long been hampered by a false tradition, and incidentally it has dragged philosophy with it into the slough of subjectivism. Brilliant discoveries in the realms of physiology and pathology throw new light on many of the fundamental concepts of psychology, spite of the fact that the investigators themselves have sometimes been misled by the old tradition. We are here concerned with their data, not with their theories. The evidence, as I interpret it, gives the death-blow to the old subjectivistic psychology. As regards sensations, the evidence shows, on the one hand, that their character is independent of consciousness; but, on the other hand, it equally disproves the assumption that the sense-qualities exist in the physical world just as we know them and independently of the organism. The evidence further shows that the centers of the central nervous system constitute a hierarchy of energy patterns, not storehouses or factories of content, sensational or imaginal. The content is due to lines of motion, connecting those energy patterns with the sense-organs. The processes of selection, suppression, and integration at the various levels of the nervous system are due, not to consciousness, but to the characteristic energy patterns of these levels. There is no reason to limit consciousness to any particular level, though we can have evidence of it only in connection with one type of pattern, viz., meaning patterns. What con-
( 426) -sciousness contributes in connection with the various energy patterns and their excitement is the bare fact of awareness. It is not an explanatory principle. Furthermore, so long as we regard the individual in the abstract, we do not require the concept of mind. We can explain behavior in terms of neural patterns and their stimulation. It is only when we take account of social relations that we find it necessary to introduce mind. In neither case do we invoke consciousness as a principle of explanation. With this brief introduction, we shall now proceed to the examination of the evidence.
THE NATURE OF SENSE QUALITIES
In the annals of psychology nothing more heroic has been recorded than Dr. Head's subjecting himself to vivisection in cutting certain nerves that supply the superficial organs of cutaneous sensation. The evidence thus arrived at has been corroborated by a mass of pathological cases, especially from the late war. The evidence is so familiar that it will only be necessary to state it in outline. The elimination of the functioning of the superficial organs strips bare the deeper sensibility and reveals its quality. These deeper organs of muscles, joints, and tendons respond to pressure and to pain. They furnish a fairly accurate localization in space. And it is they which furnish the impressions which when conducted to the cortical field, give us the sense of passive posture or three-dimensional space.
When recovery begins to take place, the primitive punctate or protopathic system becomes active and confuses the process of localization. The protopathic system responds, through its punctate organs, to pressure, hot and cold, and pain. But its responses are diffuse, massive and primarily affective. It informs us, not of the qualities of things, but of how stimuli affect the organism. It centers in the optic
( 427) thalamus rather than the cortex. It is adapted for defensive withdrawal of the body, not for differential reaction having reference to the part affected. Its responses are crude and non-discriminative. It is characterized by the `all or none' reaction. It responds to extensity of stimulation, not to graduated intensity. Nor does it respond to localized stimulation. The stimulations radiate to distant parts. They lack control. It cannot discriminate the two points of the compass. It is different when the healing process is complete and the epicritic system appears. This superimposes control upon the crude mass response of the protopathic system. The sense stimulation no longer spreads to distant parts. We can now project points, i.e., respond to the locality stimulated. The `all or none' type of reaction disappears and the response is approximately graded according to variations in intensity. We can now take account of the physical qualities of things as well as the affective qualities. We can discriminate simultaneous and successive points in two dimensional space. Adaptation, which is absent on the protopathic level, returns. All this of course presupposes the intactness of the central nervous system. The epicritic system is ultimately centered in the cortex, as the protopathic in the optic thalamus.
The sense-organs are characterized by structural differentiation, and upon their reaction to external stimuli depend in the last analysis the different sense qualities. We cannot follow the assumption that these qualities are merely transmitted from the external world. If we compare the sense organs to resonators, they are at any rate not neutral resonators, but contribute a differential quality of their own. They are specific energies. The cold spots will respond to temperatures below 22º C. with a characteristic cold quality. But they will also respond, in the absence of inhibition from the hot-spots, with an ice-cold sensation to temperatures of 45ºC., which when applied to the hot-spots or the general surface give us a sensation of pleasant warmth. In the absence of the functioning of the cold-spots, the hot-spots respond to stimuli of 22º C. with a characteristic warm
(428) sensation. Sensations, in other words, are compound energies. They depend, to be sure, on the character of the stimulus, but they depend also on the energy complex of the sense-organs. This is especially evident in the case of the chemical senses which at any rate include all but hearing, if not the latter. It is as absurd to suppose that the physical vibrations, which our physical instruments reveal, are red or green, as to suppose that they are cold or painful. It happens that we carry a polychromatic camera in our heads. But we can also construct polychromatic cameras that can see colors. Neither the cameras in our heads nor the artificial cameras can see color unless they possess the specific energies to respond in a characteristic way. Sensations are ordinarily physico-physiological processes, though they can, under certain conditions, be produced by the organism independently of the physical stimulus. We have no evidence that they can be produced in the absence of the specific conditions furnished by the sense-organs or similar organs. Even in the case of sound, though we carry a harp in our ears, be it the basilar membrane or some other organs, we know that harps respond with a quality of their own. Sounds, too, are compound energies.
While we hold to the specific energies of the senses, this does not mean that sensations are transmitted to the cortex just as they result from the reaction of the senses. The evidence of Dr. Head and others shows that the crude sensations undergo selective analysis and new integrations on the way to the cortex. This, however, does not necessarily mean a change of specific quality. We are not in a position to dogmatize about the difference which the various neural patterns make to the sensory impulses as they are permitted to pass the hierarchy of `vigilances.'  But, at any rate as regards the cortical field, pathological evidence goes to show that there is no raising of the threshold unless the cortical injury be very extensive. The difference between the normal reactions and the pathological may be reduced to one of
( 429) `clearness.' There is a lack of `clearness,' 'pointedness,' `sharpness' in the case of a cortical lesion affecting certain parts. This leads to uncertainty, hesitation, guessing, and hallucination. It is a failure in discrimination or a difference in attention. What holds on the cortical level probably holds in the case of the neural levels below it and their pattern reactions. In any case there is no reason to suppose that the characteristic qualities of sense-impulses are altered. And what is true of sense-impulses, holds equally of affective qualities. While the optic thalamus seems to be peculiarly the center of these qualities, the discrimination of intensive graduation within these qualities and their weaving into the complex patterns of emotions and sentiments, with their objective reference, must be peculiarly the work of the cortex. In any case the affective qualities do not owe their nature to consciousness.
SELECTION AND INTEGRATION IN TERMS OF NEURAL LEVELS
If the evidence disproves the subjectivistic interpretation of sensations, it no less breaks down the subjective view of the selection and integration of sensations. We can state the selective and integrative functions in purely physiological terms. They are present at all the levels of neural reaction and do not, any more than the data, owe their character to consciousness. We can thus give a physiological statement of the 'subject-object' relation. For the subject relation means the selection of data with reference to certain ends, whether these ends are ingrained in our nervous structure as a result of biological heredity or are further elaborated in terms of the life history of the individual. Obviously the first subject reactions must be biological, as individual history must start somewhere; but throughout individual history our selective activity is fundamentally determined by biological patterns, however much overlaid by individual experience. At each level of the nervous system, selection is conditioned by the unique neural pattern of that level as it is organized in terms of race and individual history. The object consists of the afferent impulses which are selected
( 430) and integrated by the pattern, or rather hierarchy of patterns, and which thus become effective in guiding conduct. The afferent impulses may figure as part of either the subject relation or object relation. They are part of the object relation when they are selected as data to be integrated and acted upon. They are part of the subject relation in so far as they are the rebound of the selective activity and figure as part of its tension, as for example the motor sensations in active attention. They become, then, means of selection, not data which are selected.
Let us now try to make our meaning clearer by examining the functions of the central nervous system at various levels. The nervous system consists of a hierarchy of fields of energy or controls. These fields must be thought of in physiological rather than in structural terms, though of course they have structure. The structure, however, is too complicated for us to follow its internal dynamics. It is fraught with a past of indefinite duration of which we know little. We must therefore be pragmatic and judge neural structures by their functions. While these energy fields differ vastly in complexity and in their characteristic patterns, they have certain essential characteristics in common. Their part is to select, sort into kinds, suppress incompatible impulses and facilitate compatible, and finally redirect or integrate these impulses so that they may be carried out in accordance with the needs of the organism. Their adaptation throughout is of the trial and error kind; and it is clear that natural selection has acted effectively to eliminate the conspicuous failures of nature's experimentation, even though natural selection as a purely negative agency is barren so far as producing adaptation is concerned.
The sorting process begins at the first synaptic junction in the spinal cord. The sensory impulses of hot, cold and pain cross to the other side and travel along separate secondary paths. The tactile impulses travel both along the posterior columns and along secondary paths as far as the top of the spinal cord before they all cross into secondary tracts. Like impulses are grouped together from all three systems--
( 431) epicritic, protopathic, and deeper sensibility. Thus the tactual sensations from the three systems are combined. Impulses of hot, cold, pressure and pain proceed along separate paths to the optic thalamus which is the center for the crude discrimination of these sensations, but especially the center for the affective qualities of comfort and discomfort. The three sensory qualities of space are bound up with the tactile impulses along the posterior columns of the spinal cord; but above it they follow each a separate path through the fillet of the optic thalamus to the cerebellum and cerebrum.
The cerebellum has to do with the control and regulation of the postural and tonic aspects of muscular activity which involves complex discriminations and adjustments, though we do not ordinarily associate consciousness with such activity. The cortex is the organ of objective cognition. On it depend, in the first place, the more delicate discriminations of data. It is only at the cortical level that we discriminate graduated intensities of stimuli. It is also the supreme organ for spatial discrimination in the three dimensions--point localization, discrimination in two-dimensional space, such as the two compass points, and the sense of posture. The last implies a cumulative sense of positional values, or what Dr. Head calls a schema, which, however, must be understood as a cortical pattern reaction and not a contribution by consciousness. The cortex discriminates the physical qualities of size, shape, weight, and texture and makes graduated comparisons possible within those qualities. It also has the capacity of recognizing a series of minute and vibratory differences, thus giving us our immediate sense of duration. With the recognition of sense differences goes the projection of lines of reference to the parts affected, without which the information conveyed would be of no practical value, and this capacity depends primarily upon the cortex.
IMAGINATION PATTERNS AND SENSATIONS
The cortex is not only the great organ for objective discrimination but also the great organ for establishing relations between data. For this complex pattern reaction of
( 432) the cortex, we may use the term meaning. Pathology  indicates a considerable specialization within the cortex for meaning reactions. The meaning of single words or names may exist when the propositional meaning of words is lost and vice versa. Both kinds of meaning are lost in deep semantic disorders. Meaning to a certain extent may exist spite of failure of verbal expression. The patient may still be able to point to things signified. However crude such recognition in the absence of language expression may be, it should give us pause from identifying meaning entirely with language mechanisms, valuable though the latter are as instruments of meaning and indeed indispensable for its abstract elaboration. There is of course ample evidence for language mechanisms taking the place of thought, but then we no longer have the process of thinking.
It is evident that the great superiority of the cortex lies in the perspectives which the meaning patterns make possible. As it is equipped with the `long distance receptors in space,' especially sight (as pointed out by Sherrington), so it is equipped with long distance receptors in time. While in the lower centers, such as those of the spinal cord, the past endures as condensed in their present structure, this responds only to present stimuli. The cortex, on the other hand, through its memory patterns can respond differentially to distant events in time. Again, through its anticipation patterns, it can project events into the future and build the bridge before coming to it. This hierarchy of relation patterns in the cortex, from the comparatively passive revival of past experience to the active reconstruction of experience to meet new events we shall call imagination. It is not necessary for our purpose to distinguish between imagination and thought. Or rather thought is one type of imagination. It is constructive imagination as contrasted with reproductive, though sometimes we limit thought to constructive imagina-
( 433) -tion which works with abstract symbols. This distinction has tended perhaps to draw the line too sharply between thought and artistic invention. Thought may work with concrete imagery, while artistic imagination may be singularly lacking in such material.
What I want to emphasize is that constructive imagination or thought is as genuine a type of neural pattern as is the reflex arc or the primitive instinct. In the absence of its specific cortical pattern, thought cannot be aroused any more than a reflex can be aroused in the absence of the specific neural pattern. You cannot make an idiot think, try as you may. Thought is not an instinct, as Graham Wallas intimates. It is a far more complicated pattern. It may be aroused by curiosity or any other instinctive activity; it may also be aroused by sensations. But it may act from its own peculiar restlessness, one thought process stimulating another. Thought is not to be regarded as a beast of burden of our lower propensities, as the anti-intellectualists maintain, though it may be evoked, and should be evoked, to guide and control the instincts. It may, however, work for its own creative satisfaction. Its bodily expression varies with temperament. It may be organic as in what Fouillée calls the `sensitive temperament'; and then one can think best by lying flat on one's back; or it may be motor, and then one can think best by giving the large muscles play. It is essentially social, and so implies the need for expression of which language is an instinctive neural pattern.
And now we must say a word about images. The pathological evidence indicates that images play at most an unimportant part in behavior. Postural images may be present as vivid as ever in a cortical lesion on one side of the cerebrum, but such images are impotent to guide postural adjustment. They lead neither to effective recognition nor appropriate expression. Evidently images have been much over-rated by traditional psychology. But what are they? Since Galton there can be no doubt that there are marked differences in concrete types of imagination, i.e., in the relation of imagination patterns to the different organs.
(434) Some peoples' imagination relates more to the eyes, others' to the ears, etc. But this does not mean that the cortex fabricates a peculiar content, whether sensations or images, nor that it stores content. There is no more reason to suppose that the cortex stores or fabricates content than to suppose that the spinal cord does so. The neural centers of the various levels are systems of energy patterns of increasing complexity and uniqueness. They are not store-houses of content. What they store are lines of motion as potential energy. All content is sensational and exists only in the degree that the senses are active. All the real evidence points that way.
In the first place, it is impossible to distinguish between imaginative content and sensational content at the minimal level of intensities. This is what gives rise to the troublesome complication of `expectant attention' in our experiments. If imaginative content had a unique quality, as some maintain, this confusion should not exist. We should no more confuse an image with its corresponding sensation than we confuse color with pressure, even at minimal intensities. In the second place, much at least of what has been supposed to be imaginative content is proved upon inspection to be sensational. This is particularly obvious in regard to motor imagination. But there is good reason to believe that it holds of all the types of content in imaginative activity. In the third place, we can arouse bona fide sensations through imagination. Imagine yourself riding on the back of a tiger, and you will find that you have veridic sensations of shiver all over. To a certain extent you can control the succession of color fields in the case of visual imagination when it is directed to producing color fields on the retina, and some experimenters claim to have complete control. Moreover, if you extrovert your attention in the case of a vivid visual image, you will find it on the retinal field. At least that has been my experience. Of course the pattern is cortical. A Scotch plaid would not happen by chance on the retinal field.
The anatomical mechanism, by which such sensational content is furnished, in the case of imaginative activities, is
( 435) obscure for the most part. In the case of motor imagination the sensational content is sufficiently explained by the close connection between meaning patterns and expression patterns in the cortex. The sensational content is the afferent result of this arc. But we cannot see how the motor adjustment of the eye could give us anything but motor sensations. It could not account for the variety of visual patterns that imagination furnishes. And the same problem meets us in the other sense departments. There is, to be sure, a close connection between incipient articulation and internal hearing, but it hardly seems sufficient to account for the range of auditory values of a symphony, considering the limited range of our vocal organs. They couldn't very well supply what they cannot produce, though they no doubt are contributory. It has, however, been definitely proved that there are centrifugal sensory fibers running from the sensory centers of the cortex to the sense organs as well as centripetal sensory fibers from the sense-organs to the cortex. Such centrifugal fibers have been found where they seemed least likely, viz., in the ear. We have here, it would seem, the required physiological mechanism to account for imaginative content.
We may hold, I think, that the imaginative patterns in the cortex are connected by lines of motion, centrifugal as well as centripetal, with the sense-organs of the body; that what is stored is not content but lines of motion, thus connecting the meaning patterns with the parts of the body; that imaginative revival means that these energy patterns are brought into play and communicate their motion outward to the sense-organs, which if the excitement is sufficient to overcome their inertia respond by sending sense impulses to
( 436) the cortex. Unusually high excitement in the cortex would tend to produce illusion and hallucination. We can thus account for the proof-reader's errors and for our supplying the pianissimo treble notes which the player only feigns supplying; and we can understand why people see life-size ghosts with clothes on, just as they expect or fear they will. Individual variations of permeability in the direction of certain sense-organs would account for the relative dominance or absence of certain types of imagery. The fact that images do not ordinarily come ready made but are the result of fixation by attention, voluntary or involuntary; that, moreover, they increase with attention in vividness and definiteness until they result, as they often do, in veridic, and not merely nascent sensations; that under such circumstances, if we are careful observers, we can notice a corresponding excitement in the sense-organs-all this fits in with the above theory. Cases of insistent images can be shown to be due to an insistent cortical pattern which has established unusual permeability for itself in a certain sensory direction. We can account for negative after-images, resulting from imagination, which, however rare, are now acknowledged to be veridic, i.e., some observers in imagining red have succeeded in getting a negative after-image of green. The theory would also help to explain various phenomena of centrally initiated pain sensations, so familiar to the pathologist. But the psychological reader can easily multiply instances where the theory would be useful.
It is not difficult to account for what has been termed imageless thought on the above theory. In the first place, there is wide variation as regards the presence of concrete imagery and in some individuals it is largely absent. But further than that, when the attention is absorbed in the search for abstract relations, there is a tendency to suppress the revival of sensational impulses, for these might confuse rather than increase the effective working of attention. The law of economy operates to suppress the useless and to emphasize that which tends to further the end involved. It seems, moreover, that a continuous tendency to suppress
( 437) concrete imagery leads to atrophy of the functions of revival in that direction or, in other terms, tends permanently to block expression of that type. We recall as a familiar instance of this the regret expressed by Darwin in his later life that he was no longer able to enjoy music or poetry which had been an important part of his life in his earlier years. Coupled with this regret was a feeling that such loss of concrete appreciation had probably caused a deterioration of a moral kind.
It has been suggested as an objection to the above theory of imagination that people who have lost an arm or a leg still have the feeling of a `phantom' arm or leg, which, according to some, seems shrunk and smaller than the other. The evidence is by no means unambiguous, but it would seem that in such cases it is visual imagination and not tactual which furnishes the pattern. Dr. Head has shown that the image of the phantom limb, which may exist in cases of lesions on one side of the cortex, has no value in recognition or postural adjustment. If the patient's affected hand is moved after his eyes are closed, and he is asked to indicate its position, with the other hand, he will point to the place where it was when he saw it. As to the sense of shrinkage or shortening, that would seem to be a matter to be interpreted in terms of tactual sensibility. Since the sensational response to the projected sensory lines is actually cut short and shrunk in bulk, the fact would be just what we should expect on the theory we have advanced. On the other hand, if the sensory processes are cortically produced there seems to be no reason for any shrinkage. Another objection which has been raised is that persons whose eyes have been removed, including the retina, still have visual imagination. It is necessary to have more definite facts before attempting to answer such an objection. In the first place, the term image has been and is a very ambiguous word; and it is therefore difficult to know what people mean when they speak of an image. There would still be meaning patterns directed towards the eyes, though there were no concrete imagery. Again, the actual facts of the operations
( 438) would have to be established. In the nature of the case there could be no objective test, and the introspective test must always be uncertain. Furthermore, we are under a peculiar difficulty in the case of the end organ of vision, owing to its being, as it were, a projected part of the cortex. We cannot be sure how much is included in the organ of vision. But in both of the above objections the facts are still too much in the nature of old wives' tales to be taken seriously; the important thing is that the theory should meet the ordinary and established facts.
SUPPRESSION AND NEURAL LEVELS
The sorting and integration of sensory impulses would be useless except for another function of the nervous system, viz., that of selective inhibition or, to use Dr. Rivers's term, suppression. A certain `vigilance' is exercised by each neural level which permits only those impulses to pass which fit in with the general set. There is a constant struggle for dominance amongst incompatible impulses at the various levels. Were all allowed to reach the highest level of discrimination, there would be endless confusion. But only the victors reach the higher levels. Which among several competing impulses emerges as victor not merely depends upon the quality, intensity and duration of the preceding impulses but implies the entire history of the nerve-center,-the duration of previous lines of motion, whether of race history or individual history, as structure or potential energy. And we must take account not only of the set of the individual center, but of its relation to the levels above it which under normal conditions to a large extent control its behavior. Prepotency is, therefore, a very complex affair and can be studied by us only as revealed in function.
It is easy to illustrate the fact of suppression in connection with sensory impulses. Suppose you apply a metal disc of
( 439) a temperature of 45ºC. to the back of your hand. You stimulate not only the hot spots, but the cold spots, the pressure spots and the pain spots. Yet the sensation is one of pleasant warmth. The other impulses, under normal conditions, do not reach the cortex. This does not mean that they are absent. Pathological cases show us that they are always present, ready to come to light when the epicritic control is removed. Visceral sensations are always present, but it is only under abnormal conditions that they reach the highest discriminative centers, and this because their information becomes important for self-preservation. The suppressed sensations, moreover, may count, even when they do not reach the higher levels, in guiding reflexes of the lower centers.
It is, however, not only in connection with sensory impulses that the nervous system selects the compatible and suppresses the incompatible. The principle holds throughout. Dr. Rivers  has shown how within the cortical level there are various strata, due in the first place to organic evolution, with recapitulation in part at least of its main periods, but overlaid in the course of individual development. Here we have again the struggle for dominance of the various tendencies of the more primitive levels, on the one hand, and the epicritic control by the later levels, on the other. The earlier strata, such as the infantile level, the childhood level, the adolescent level, etc., do not disappear in the later life of the individual, but the crust of custom of the upper level exercises strict `vigilance' over them, and we may not under ordinary circumstances suspect their presence. Their suppression may, however, very much complicate the life of the individual; and they are ready to assert themselves with excessive vigor when the ordinary `vigilance' is relaxed. How to reduce the suppressed tendencies to a minimum by integrating them into a comprehensive scheme and sublimating them into the activities of normal life is a problem not only for the physician but for society at large.
NEURAL FUNCTIONING ILLUSTRATED IN MORE COMPLETE REACTIONS
Our emphasis so far has been upon the sensory and cognitive functioning of the organism. But we might have selected the more complete reactions with equal effect. The cognitive aspect does not exist by itself, but is bound up with the executive and motor aspects, and their complicated systems of patterns. The more thoroughgoing is the cognitive or informative function, the more definite and adequate is the affective or motor aspect. In the case of the reflex arc, the simplest complete neural act, we have the selection of sense impulses, the suppression of incompatible impulses, the integration of impulses into the prevailing pattern and finally the projection of lines of action to the part affected. This of course assumes the intactness of the central nervous system. In the conflict for dominance in the neural centers, the physical law of summation of forces, as Sherrington  points out, does not hold. When the flexor reflex and the extensor reflex conflict, the result is not an algebraical summation, but one or the other becomes prepotent; the other is suppressed. Orderly succession of adjustments means the supersession of one reflex or group of reflexes by another. It means the passing from one reflex pattern to another, determined in part by the quality and intensity of the stimulus, in part by the set at the time of the neural center, this set being due to its previous stimulation and constitution on the one hand, and its relation to the higher centers on the other. Thus coördination is established as between reflexes; and the ends of the organism are furthered.
The simplest neural centers thus reveal the essential traits of group conduct. "The nervous system," says Sherrington, "is in a certain sense the highest expression of what the French physiologists term the milieu interne."  We may look at nerve-cells from three points of view. In the first place, we must take account of them as individuals. "Nerve-
(441) -cells like all other cells lead individual lives--they breathe, they assimilate, they dispense their own stores of energy, they repair their own substantial waste; each is, in short, a living unit, with its nutrition more or less centered in itself." In this respect nerve cells are like other living cells. In the second place, nerve cells present a high degree of contagion. "They have in exceptional measure the power to spatially transmit (conduct) states of excitement (nerve-impulses) generated within them. When we approach the problem from the social point of view we find a similar relation between individual organisms. This phenomenon is especially prominent in the case of crowd excitement and certain artificial and pathological states. In the third place, the reactions of nerve cells have the function of integration. "In the multicellular animal, especially in those higher reactions which constitute its behavior as a social unit in the natural economy, it is nervous reaction which par excellence integrates it, welds it together from its components, and constitutes it from a mere collection of organs an animal individual." The simplest level of conduct, that of the reflex arc, thus foreshadows the characteristics of the most complex levels of behavior, including the interactions of the highest organisms.
If we turn now to the instincts and emotions, we find the same fundamental functions of selection, suppression, integration, and projection. They have, as McDougall has pointed out, their cognitive, affective and motor aspects. Cannon  has shown that emotions owe their specific and unique character to their being neural pattern reactions, resembling in this respect reflexes such as sneezing, though of course vastly more complicated. "They are ingrained in the nervous organization," and respond "instantly and spontaneously when the appropriate `situation' actual or vividly
( 442) imagined is present." They are, among the higher animals, for the most part cortical patterns, but Sherrington's experiments on decorticated dogs and cats show that `at least one such pattern, that of anger, persists after the removal of the cerebral hemispheres.' We cannot, it is true, neglect expression as a factor in emotions. They `gain expression through discharges along the neurones of the autonomic nervous system,' and in this way get what James called their `bulk.' But the setting off of the autonomic system depends upon the intensity of the emotional stimulus rather than its specific character and could not possibly differentiate the emotions.
That the emotion patterns are genuine energy patterns is shown by their effect upon secretions and muscular contractions and by their stimulation of the adrenal gland which increases blood sugar in intense excitement. It is also shown in pain and great emotion by the `hastening of the coagulation of blood' and in general by the `energizing influence' which `the fierce emotions' exercise.
The sentiments, again, as Shand  has shown, manifest still greater complexity of pattern. This is due in part to inherited connections between emotions. "Every primary impulse, whether it is independent or belongs to a primary emotion, is innately connected with the systems of fear, anger, joy and sorrow in such a way that when opposed, it tends to arouse anger, when satisfied, joy; when frustrated, sorrow; and when it anticipates frustration, fear; these symptoms being similarly connected together." In the case of such a complex sentiment as maternal love, the innate connections are immensely complicated. But the complexity of patterns increases vastly in the course of individual experience as the emotions become organized in terms of patterns of imagination and their objective implications. In general, "every sentiment tends to include in its system all the emotions, thoughts, volitional processes and qualities of character which are of advantage to it for the attainment of its ends, and to reject all such constituents as are either superfluous or antagonistic." The sentiments tend to form a hierarchy in
( 443) which greater systems are superimposed upon lesser systems, including the bodily systems, until a character is formed, the more inclusive systems exercising `vigilance' over the more primitive. They are in Shand's phrase, "forces; they work in certain ways and in certain directions. They arc within us to perform certain functions."
That the meaning patterns of the cortex are an integral part of the complex volitional arc and issue in certain definite motor patterns for the control of conduct is attested by the whole trend of modern psychology. The motor patterns owe their definiteness and control to the meaning patterns and in turn make them effective. No impression without expression is a psychological commonplace and holds of the cerebral levels as well as of the lower levels. Language patterns are only one form of this expression, though socially a very fundamental one. All the facts go to indicate that we must regard the nervous system as a hierarchy of energy systems with increasing complexity and interconnection as we proceed to the upper centers. Each level has its own quality or functions which pathological evidence has enabled us to dissociate from the total system.
We must not forget the integrity of the nervous system, when we talk about the reaction of nerve centers. It is a singular fact that the lower centers owe their definite and stereotyped functioning to the control of the upper centers. In the case of stimuli of high intensity, the control is broken; and then the lower centers act in an indeterminate and unpredictable way. When through accident the lower spinal centers become separated from the upper part of the nervous system, they respond by mass reflex and in other diffuse ways. They no longer project their response to definite points, but relapse to the old defensive reactions of withdrawal of the entire part of the body.
If it is true that the lower centers are dependent upon the upper, it is no less true that the upper are dependent upon the lower. This dependence, moreover, is not merely an execu-
( 444) -tive dependence but concerns the whole life of the upper centers. We all know how deeply rooted are the instincts and emotions in the primitive reflexes of the organism. And the sentiments in turn are rooted in the emotions. But imagination, too, even in its highest stages of creative organization, is closely dependent upon the primitive part of us. I have in mind, not merely the serious complications of the sex life which often accompany intense work of the higher type, but the more positive fact that our higher activities draw their energy, color and zest from their aliveness to sense experience and the passions. This will no doubt be recognized with reference to the more sentimental imaginative activities, but it is true of abstract thought, too. No person who is a mere intellectualist is likely to make any profound discovery or to move the imagination of human beings. The really great thinkers are poets at heart. And it is when we express the emotions rather than when we repress them that thought takes wings, that creative imagination comes to free and momentous expression. Your dry as dust intellect may do valuable secondary service, but it is not likely to do first class work. You must have a passion for beauty or your fellow men or something greater than yourselves to sustain great thought. There is something almost infantile and primitive about genius that ensures youthful freshness to its work and makes its world a world of perpetual wonder. This is merely another way of saying that the great and fruitful intellect is not a mere cerebral language machine but lives clear down to his toes. All the levels are tapped and converge to give reality to his thought. The whole organism, and not least the despised parts below the diaphragm, contribute their vital share to the real life of creativeness. Your whole cubic capacity must be alive, to borrow an expression from William James, if you are to do your best intellectual work.
CONSCIOUSNESS NOT AN EXPLANATORY CATEGORY
So long as we limit ourselves to the individual organism and its implications, we can project all our facts on one plane,
( 445) viz., that of physiology, even though we are under the necessity of borrowing some of the terms that have been associated with psychology. In the first place, there is no need to take account of consciousness. We may regard it as a universal property. It is a fair assumption that it is present on all the levels, even though it is only on the cortical level that it becomes significant and therefore known. There are limiting cases of well-nigh pure perception in our experience, but these are remembered because they issue into processes which have meaning. Consciousness in any case accounts for no processes. These must be explained in terms of our reaction patterns and their lines of relation to the terminal organs which furnish our data. Consciousness is everywhere a neutral light. It is not consciousness that colors the processes. It is they that color it. It is not consciousness which gives unity to our energy patterns. It is they which give unity to it. Consciousness controls no reactions. These are controlled, in so far as they are controlled, by the system of energy patterns of each level and of the whole. Consciousness is therefore useless for explanatory purposes and we can cancel it, as we cancel a factor in an equation when it figures in the same way on both sides. To be sure, there is the fact which Alexander has called `enjoyment'; but this owes nothing to consciousness except the bare awareness, and in any case the fact would not be patent in a solipsistic world. There are, of course, different levels of control with
their conflicts and subordinations. It is true that the great mass of our life lies below the cortical attention level with which we usually identify our ego. But this complexity of levels and controls is in no wise explained by consciousness. I suggested some years ago the awkward adjective, subattentive, for the levels below the customary crust.
The concept of consciousness has long been a stumbling block to a consistent account of behavior. It has been felt that there is an impassable gulf between consciousness and physico-organic causes and effects. Huxley says: "How it is that anything so remarkable as a state of consciousness comes about as the result of irritating nervous tissues, is just
( 446) as unaccountable as the appearance of the Djin when Aladdin rubbed his lamp in the story." And Tyndall says: "The passage from the physics of the brain to the corresponding facts of consciousness is unthinkable." The answer is that there is no such passage. The physiologist in describing behavior in terms of physico-organic mechanism never runs across the fact of consciousness. It is not an energy category and therefore does not figure in the chain of causes and effects. It constitutes another dimension from energy at any of its levels, physical, organic or mental. It is not originated by energy changes, neither does it originate energy changes. It is therefore irrelevant to causal explanation. It is relevant only when we deal with the significance of behavior. And what it contributes is merely awareness.
MIND AS A SOCIAL SYSTEM OF PATTERNS
If the study of individual behavior in the abstract does not require the concept of consciousness for explanatory purposes, neither does it require the concept of mind. It is entirely arbitrary to identify mind with any special level of the nervous system. All the levels, we have seen, have the same essential characteristics. They all discriminate, inhibit, reinforce, integrate, and project in accordance with their unique energy patterns and their relation to the economy of the whole. Individual psychology is an unreal abstraction and in fact is not psychology at all. It is a misnomer. We can, it is true, study the human individual as a system of indicative signs or implied meanings, just as we study geological strata or the life of plants. But this is behavior as the physiologist studies it and should be called what it is, viz., physiology.
The issue has been confused by the fact that psychology so-called has followed no consistent principle of explanation. When it has dealt with the more elementary processes of habit, emotion and sense perception, it has leaned on physiology or pretended to do so. When, on the other hand, it has dealt with the more complex processes, such as the sentiments, thinking and will, it has fallen back on social
( 447) psychology. It has as a matter of fact started with the adult behavior of the psychologist as differentiated, integrated and stereotyped through social relations, but has abstracted from those relations. Instead of treating of the individual within the matrix of social relations, under the control of which he acquires his habits, attitudes and perspectives, it has made him an abstract entity. It has forgotten that the world as it exists for the psychologist, with its things, qualities and relations, its values and attitudes, its play of free ideas and its organized will, is the product of social communication and interaction, made possible by a highly evolved language and tradition. The physiologist, who starts with the simple reflex of the nervous system and follows this through more complex levels of selection, integration and control, at any rate is consistent in his explanation. In the most complex behavior of the organism he sees the play of ever more complex mechanical causes. And though these may not furnish the sufficient reason of the behavior, they at any rate are an index of behavior and make a consistent story. If consciousness is present in this account it is at any rate irrelevant so far as explanation is concerned. It is assumed that the organic mechanism in its entirety,-neural, chemical, physical,-would indicate all the various complexities of behavior, could we follow it, which we cannot. At any rate, it is all we have so long as we deal with the individual organism in the abstract.
Mind is essentially a system of intersubjective meanings or valuations and of controls as resulting therefrom. We may speak of mind as a superorganic system of relations as we may speak of life as a superchemical system. In any case each is a unique type of energy system with characteristics of its own. In the absence of expression, mind is inchoate and ineffective. It can at best be regarded as potential from the spectator's point of view. The formative idea is the soul whether in the individual or in the group. And this is created in social relations and can only be understood through social relations. Mind comprises, it is true, relations to the physical world as well as to the social. But the former exist
( 448) as meanings only because they are selected and integrated into social patterns. The physico-organic concept of mechanism employed by physiology is itself such a socially constructed system of patterns and should be worked so far as it can be worked. But it proves inadequate when we come to deal with social relations. I may add in passing that it is not necessary that the formative idea or system of ideas should be conscious at all times. It is at most only partly conscious at any one time; and at times, as in sleep, it may not be conscious at all. The mental patterns are, no more than the neural patterns, dependent on consciousness for their existence, though they cannot have significance without consciousness.
It is only when we are concerned with expressive signs, with social relations, that the concept of mind becomes necessary. Here we have a new perspective of relations, a new reading of the facts. We no longer deal with neural patterns except as instrumental to the new type of relations. We are concerned with a new type of energy field where will relations, the craving for association and reciprocal sympathy, the intention to express and to be understood, the desire to share in a common life become the important facts. We have to do with teleological causes-the realization of needs and interests in social relations. We are concerned only indirectly and instrumentally with mechanical causes and effects. Here we have selection, inhibition, facilitation, reinforcement and integration of conative impulses, obeying in the main the same laws that we have become familiar with in the physiological field. There is the grouping of like impulses with like, there is the struggle for dominance and the selective inhibition of the incompatible impulses, the facilitation of the compatible and their integration into a common direction by the controlling pattern or set of will relations. In this pattern, duration plays an even more important part than in the physiological patterns, for here we have the past conserved, not merely in the slowly formed patterns of bio-
( 449) -logical heredity, but also in the cumulative tradition, embodied in language, art and institutions, and moulding the habits of each generation, through education and social sanctions, into conformity with itself. And we have the projection of the future, which is not merely the projection of the past but has a forward-looking implication-due to our being part of a larger cosmic order which we cannot understand but which somehow determines our course and our survival conditions. We have fusion, as in the orchestration of a vast number of musical instruments of varying timbre, of the various complex energy patterns of individuals and groups into a common tradition and a common life; and here, as in the physiological field, we have to take account of the quality, the intensity and the number of components as well as the total situation of the controlling energy field. This forms a continuum of a unique sort, cutting the individuals into various planes, protopathic or epicritic, according to the type of control and the situation at the time.
The fact that we are so organized that every instinct and emotion is provided with selective inlets or receptors for sympathetic response to corresponding instincts and emotions in others and that, further, we can only realize our nature and find our satisfaction in association with others goes to show that the evolution of life has assumed a new type of energy pattern in which the group is the unit rather than the individual, just as in the multicellular organism the organic whole becomes the unit of control rather than the cell. The types of group-unity vary all the way from the nutritive unity in the lowest stages of animal life, through the organic family of the bee, to organized self-planning society. The future is dark to us, but judging from human history so far and from our newly gained psychology of human nature, it would seem that if the race is to survive it must evolve a pattern of social relations which furnishes, on the one hand, a maximum freedom of individual human nature and, on the other hand, a maximum of sympathetic coöperation for common ends. Only such races as can meet these two tests are likely to survive in the long run.
Whether we translate the facts into mental or physiological terms, it is clear that we must explain behavior in terms of energy systems or patterns and their action, reaction and interaction with the energy patterns of the environment. We cannot on the social level, any more than on the physiological, explain behavior in terms of consciousness. The evidence shows that not only are the sense qualities and affective qualities independent of consciousness but the functions of selection and integration, or, in an older terminology, analysis and synthesis, must also be accounted for in terms of energy patterns-neural or mental according to our approach-and independently of consciousness.
The subject-object relation now becomes one of significant selection on the basis of past and future perspectives. With the aid of language mechanisms, meaning patterns, ingrained by heredity and organized by personal experience, function as judgments, expressed, supplemented and corrected in terms of social relations, present and past. Selected impulses now become data for conscious construction and reconstruction to meet the needs of life. And life includes pure thought. It takes delight in successful action, theoretical as well as practical. But in any case, the process is a trial and error process. The final test of proper thinking is proper conduct within the dominant purpose. This is as true in the realm of theoretical construction as in the sphere of practical judgment.
Mind patterns may express themselves not merely in immediate social relations, but also in forms of matter, institutions and language. A great genius may express his meaning in musical patterns of vast complexity like a symphony of Beethoven or in sculpture like the Zeus of Phidias. He may express his thought in the building of cathedrals or in systems of philosophy or in great epics. And these patterns, with the will communicated to them, continue to live in the history of the race long after the creator has passed away, thus giving his mind a continuous vitality in history for long periods of time perhaps latent for centuries but always ready to spring into renaissance when the proper
( 451) conditions arise. It is so that English culture has been organized and continues to be organized through the ongoing genius of a Shakespeare, who in turn is ever reconstructed in the living tradition of the race. So Plato lives through the centuries and makes us Greeks, while we in turn give his genius the coloring and vitality of our time. Such influences are lines of motion entering into ever new systems, yet always retaining their individuality as the historic pageant passes, dwindles or grows, through the endless perspectives of space-time.
Having once been compelled to introduce the conception of mind in order to understand social relations, we can now return to the individual and study his behavior from the social point of view. Strip the individual of all social reference and nothing remains but a bare physiological automaton. But it is different when we consider the individual as part of the group. It is obvious that meaning and language are the articulation of the need `for expression and reciprocal sympathy, i.e., they are group planes which intersect individuals. Creative imagination, whether concrete or abstract, exists to organize and give form to this need for expression and mutual understanding. The sentiments are emotional patterns moulded upon social objects in the course of group relations: Even the instincts are all equipped with inlets for social sympathy. They are highly contagious. The cerebrum, in short, becomes an organ for social interactions, past, present and future, i.e., it is an organ of mind.
As for the other neural levels, they too acquire new significance. It has been customary to start with reflex arcs and to judge the other reactions on that type. If we start with the assumptions of the physical sciences, it is natural to treat this arc as purely physico-mechanical. And having once made this assumption, there is no place where we can stop; and we are under the necessity of projecting the whole of conduct on the plane of the physico-mechanical. But we can now interpret the functioning of the lower centers from the social point of view. We can project the functioning of these centers on the plane of mind. They have their own
( 452) reality, their own contribution to make to the life of social relations. This fact is unfortunately overlaid and obscured in our artificial society. The cortex is preëminently an abstract language mechanism and its increasing tyranny over the lower centers, owing to extreme centralization of functions, tends to suppress unduly the more primitive functions. Under artificial conditions such as hypnosis and the spontaneous trance, and in the less abstract life of primitive peoples, we have an opportunity to observe a more immediate and more nearly protopathic sense of social relations which is largely suppressed in us except under conditions of extreme crowd excitement. The increasingly abstract epicritic control gives us our intellectualistic theories of individualism, so foreign to primitive society. We must, I think, presuppose an immediate protopathic sense (however overlaid and difficult to disentangle) of social presence which constitutes the sense of reality of social relations. It furnishes the primitive continuum which is canalized and overlaid by the later epicritic cognitive functions and only under unusual conditions rises into the attention-field. In genius there seems to be an unusual persistence of the protopathic type of immediacy and hence an unusual liveliness of the immediate and first-hand values.
The question may well be raised whether the extreme cortical centralization of the organism, with the consequent suppression of the primitive sense of rhythm, movement and concrete imagination, which is the course of civilization, is not a tendency to senility and therefore self-defeating. If the psychic attitudes make a difference, directly and indirectly, to the blood, and if the blood in turn makes a difference to the germ-cells, then it may well be that the absence of proper stimuli and interactions may cause certain tendencies in the germ-cells to atrophy or at any rate to make them available only under such exceptional conditions as to make them of little service. This should give us pause in our artificial and murderous civilization.