De psychon-theorie van het bewustzijn

THE question, " What is consciousness ? " has been asked, but not answered, since the first dawnings of speculative thought. The present age, however, can boast of a new question all its own : " Does consciousness exist ? " To one whose common -sense life has been spent outside the intellectual fantasies of academic shades this question might seem ludicrous. Nevertheless, professors of the older school are beginning to experience a considerable degree of bepuzzlement when confronted with the task of convincing a healthfully sceptical younger generation that there is such a thing as consciousness.

" What is it ? " ask the student readers of Watson. " Where is it ? Prove to me that consciousness exists ! "

In vain does the instructor insist that " everyone knows what consciousness is, because everyone is conscious "; that " many phenomena which cannot be ' kicked ' (seemingly the prescribed behaviouristic test for recognizable beingj, can yet definitely be shown to exist."

" Very well ", reply the students, " show us, then."

Objective evidence of the existence of consciousness must necessarily be indirect evidence, just as is the case with electricity, Hertzian waves, and even disturbances of propagation in nervous tissue. No wireless wave, electric current, or nerve impulse is in itself sufficiently tangible to be made subject fo observation by human senses aided by such instruments as are at present available. The effects of these various forces upon observable materials, however, are accepted not only as proofs of the existence of the forces under

1 " The Psychonic Theory of Consciousness " made its first appearance in the Journal of Abnormal and Social Psychology for July, 1926. The theory was amplified in an article appearing in Psyche for July, 1927. Portions of both ai tides are reproduced in this chapter, and the author makers grateiul acknowledgment to the editors foi their kind permission to reprint the material.

examination, but also as scientifically descriptive criteria by which the nature of the unseen causes may be determined. Thus, an electric current may actuate a voltmeter or an ammeter; a Hertzian wave may produce differences of conductivity within an audion tube; and a nervous impulse may

result in easily recorded contractions of a strip of muscle fibre.

If, then, examination of consciousness is approached with similar objectivity, we must assume that consciousness itself, or the physical mechanism used to produce it, constitutes a definite, physical force, capable of registering its presence and nature by causing changes in some observable material. Further, this force, consciousness, if it exists anywhere, is to be found in the more complex reactions of the normal, adult, human being. In terms of the preliminary analysis of causation arrived at in our last chapter, we are now called upon to prove that a vitalistic-type cause called consciousness actually exists in some part of the human organism and that this supposedly complex form of energy exerts a measurable influence upon simpler energy units, within the body itself, capable of observation with the unaided senses or with laboratory instruments.

Most of the human family have observed, without the aid o* a psychologist, that some human activities seem to the subjects themselves to be more conscious than others. Habitual responses, luch as walking, twirling a watch fob, or swinging a stick, often do not seem to be accompanied by any consciousness whatever. On the other hand, the making of momentous decisions which may occupy many hours, days, or weeks, exemplify the type of human action which seems to include the greatest relative amount of consciousness. The question as to whether or not habitual actions are, in truth, totally devoid of consciousness may be regarded at the moment as t purely

academic. If our subjects unanimously report more of the phenomenon called consciousness in one sort of behaviour than in another, and if there are objectively observable effects which seem to proceed paripassu with the increase in consciousness, this constitutes scientifically acceptable proof that consciousness is a material force acting upon our bodies as a vitalistic-type cause. In exactly the same way, the fluctuating needle of the voltmeter is accepted as offering scientific proof of the invisible presence of an electric current acting as a

vitalis tic-type cause over the materials of the instrument. Should this causally effective force, consciousness, be identified later with nervous energy in some part of the brain, it would still remain a vitalistic-type cause, that is, a more complex form of energy than the materials moved. Moreover, when psychology has properly performed its task, we shall hope to find physical consciousness explicitly described in terms of physical energy units.

Our first question, then, is : What changes in bodily behavio.ur characteristically accompany this reported consciousness ?

Proofs of Consciousness

1. The more conscious a reaction is, the slower it is.

It has frequently been observed that the more conscious

an action is, the longer is the observable delay between reception of environmental stimuli and appearance of overt bodily responses. As already noted, habitual actions occur very quickly after contact with the stimulus; whereas, in the making of momentous decisions, overt activity may be delayed for days or weeks. Reflexes like the knee jerk, where no accompanying consciousness can be detected by the subject himself, manifest a still shorter reaction time than the habitual responses; while certain " thinking " activities, which may persist over a period of many hours, and which are, recognized as intensely conscious throughout the entire period, may never manifest a detectable ultimate response. One observable effect of consciousness upon bodily behaviour, then, would seem to be a lengthening of the time interval between stimulus and response.

2. The more consciousness accompanying a response, the longer ic persists after the stimulus is removed.

Quite in contrast to the first-mentioned result of the influence of conscious energy upon bodily behaviour is a second equally common effect. Strictly reflex, or habitual actions, tend to cease very quickly after the removal of the environmental stimulation that brought them about. For instance, a machine operator in a factory does not continue to press down the stopping lever of his machine after the machine has stopped. One does not continue to make watch-fob-twirling movements

when dressed in pyjamas, nor to swing the legs in a walking movement after stretching oneself out in an easy chair. On

the other hand, if a greater amount of consciousness is attached to a given action, the action is likely to persist for a much longer period after complete removal of the effective stimulus. Suppose a young man has responded to the stimulus of a chance remark that he is " mentally abnormal " by deciding, after some weeks of cogitation, to become a psychiatrist (an actual case which cajrie to my attention in clinic). He begins to act upon this remark within a few months by entering a medical school, but long years of training must follow before he can even begin to analyze his own personality. During these years he may not once have encountered any repetition of the suggestion that he is mentally unbalanced, but his original reaction, which was initially accompanied by intense and prolonged " consciousness " of both emotional and intellectual varieties, has persisted without abatement throughout a period of years after the disappearance of the environmental stimulus. Probably most physiological authorities would agree that such a tremendously extended response represents not a single reaction, but a long series of reactions. Since most of these responses are centrally initiated, and all are unified to accomplish a single purpose, the original stimulus must have evoked a large volume of energy somewhere in the central nervous system which continued to control behaviour for a long period of years. In conformance with this idea, R. S. Woexlworth 1 in his theory of " tendencies to action " and " preparatory reactions " holds that " damned up energy " may exist in the central nervous system for periods of months and years, escaping in tiny rivulets as the dam is punctured by appropriate environmental stimuli.

3. The more conscious a response is, the less its rhythm

corresponds with the rhythm of the stimulus.

Habitual or reflex actions show a much closer correspondence between the rhythm of end effect and the rhythm in which the stimulus is received than do more conscious responses. In the swinging of a cane or regulation of a semi-automatic machine, the rhythms of bodily response are adjusted automatically to the rhythms of stimulation. This type of adjust-

1 R. S. Woodworth, Psychology, New York, 1925, pp. 82-84..

3 o EMOTIONS OF NORMAL PEOPLE

ment is still more marked in such highly reflex activities as skilled chorus dancing, playing the piano, or using a typewriter. On the other hand, the more conscious the action becomes, the more the automatic correspondence between rhythm of stimulus and rhythm of response tends to be broken up. Let the dancer become suddenly aware of her steps, the typist of the keys, the pianist of his notes, and the established rhythm is shattered. Grace dissolves into jerky awkwardness, speedful accuracy into hesitant blundering and rhythmic harmony to lagging dissonance. " Introverted " persons, or. those customarily given to expressing a great deal of "selfconsciousness " while reacting to a stimulus, are notoriously awkward in games or physical exercises requiring close approximation of the rhythm of bodily responses to the rhythm of an environmental stimulus. Their physical actions are jerky, and indiscriminately slower or quicker than the rhythm of the physical stimulus to which they are attempting to adapt their own rhythms of action. The increased consciousness seems to interfere with the correspondence between rhythm

of stimulation and rhythm of response.

4. The more conscious a response is, the less its intensity corresponds with the intensity of the stimulus.

Within limits, the intensity of simple reactions, involving little consciousness, corresponds rather closely with the intensity of the physical stimulation. A vocalist unconsciously sings louder if the volume of the piano accompaniment is increased. Small adjustments in the reactions of walking are made " unconsciously " in response to differences in intensity of pressure stimulation presented by the path along which one is walking. A slight up grade which increases the intensity of the pressure upon the feet and also increases the intensity of muscular pressure upon the proprioceptive sense organs, is " unconsciously " followed by corresponding increase in the intensity of muscular exertion. But in responses which are reported as involving a great deal of consciousness, there may be little or no correspondence between the intensity of the stimulus and the intensity of reaction to the stimulus. In the case of the young psychiatric student just considered, the chance remark concerning his possible abnormality constituted a stimulus of slight intensity indeed. The same remark, or similar ones, had probably been made concerning nearly all of this young man's friends with no

particular effect, yet in the specific case cited it released a volume of energy regarded as " conscious ", which was probably many thousands of times as intense as the stimulus, and

which was also more intense than reactions to other stimuli much more intense than this stimulus. On the other hand, instances might be cited where increase of consciousness decreases intensity of response as compared with the intensity of the stimulus as when the singer thinks " The piano is too loud I will sing pianissimo and force him to follow ". Or the reduction in intensity of the response may be a positive inhibition this in turn to be accounted for by the positive agency of some active force within the organism. An example of an effect of this sort is to be found in the total elimination of overt actions which is caused by " pausing to think " after experiencing an irritating stimulus. One child may slap another child's face with considerable strength. Remembering the nursery adage of " count ten before you strike back ", the assaulted youngster finds that by the time he had counted ten he does not feel inclined to strike back at all. Voluntary increase of consciousness seems to have eliminated reaction to an intense stimulus altogether. Consciousness, then seems, on the whole, to alter markedly the correspondence between intensity of stimulus and intensity of respose.

5. The more consciousness attaches to subliminal stimuli, the greater is their tendency to summation.

A stimdlus evoking little or no consciousness, so far as the subject is able to observe, and which is too weak to produce a response, is not apt to bring about the reaction toward which it tends, even though the " unconscious " stimulus be repeated a large number of times. For instance, during my first two years of residence in New York City, I passed the Metropolitan Museum, riding in buses or automobiles, probably a hundred times or more, without making any move toward entering the building. On one of my earliest trips up-town a companion had pointed out the Museum, and I had formed a habit of

looking toward that side of the street in passing. But my subsequent visual sensations, though they controlled eye movements, evoked no thoughts or emotions concerning the building or its contents. In short, visual perception of the Metropolitan Museum constituted an almost " unconscious " Stimulus, of too slight intensity to arouse the reaction of

entering the building, toward which it tended; and constant repetition of this stimulus failed to bring about the final response. After more than two years of residence in the city, a guest from another part of the country chanced to expatiate, in my presence, upon the wonders of the Metropolitan Museum. This stimulus, though it intrigued my interest temporarily, and was accompanied by many fully conscious thoughts and feelings,also proved too weak a stimulus to result in a Museumseeing reaction. More than a month later another friend expressed enthusiasm concerning the Metropolitan, arousing still more consciousness concerning it. This stimulus, added to the first highly conscious stimulus, sent me to the Museum. It seems to me highly improbable that the numerous habitualview stimuli entered into the final summation of energy which brought about the response, or that another two years of viewing the building almost daily would have resulted in my entering it. One may argue, of course, that the two descriptions, by friends, of the museum's contents, were more intense stimuli than were mere views of the outside of the building; and so they were. But the point to be noted here is merely

that two stimulations which evoked much consciousness added themselves together to provoke a certain response, while a hundred little-conscious stimuli failed to bring about the same result. Many other instances of the same sort, from every-day life, might be cited. A person may gaze " unconsciously V at a store, as he walks by it, every day for months, without entering. A " window ticker " may then appear inUhe showwindow, and the subject may become conscious of a momentary wonder as to how the thing works. Next day this same consciousness concerning the ticker may again occur. On the third or fourth day the individual is likely to enter the store and purchase the cigarette or other article advertised by the ticket. It is not our present task to speculate as to how the additional consciousness was aroused by the advertising device; it is our present purpose to note that consciously experienced stimuli tend to add themselves together more quickly and effectively, upon repeated presentation, to evoke the reaction toward which they tend, than do stimuli " unconsciously " contacted.

6. The more conscious a response is, the more subject it is to fatigue.

The more consciousness accompanies any activity, the more quickly fatigue sets in, no matter whether the response is one of " thinking ", or one of violent physical exertion. Many a distance runner has found himself miraculously

refreshed by some sudden roadside occurrence that " takes his mind off " his own movements. His fatigue, in other words, becomes less when the consciousness attached to his own running is lessened. A person whose continuous occupation is " thinking " aloiig scientific lines may learn to increase his attention-span, correspondingly diminishing his mental fatigue, by ceasing to introspect upon his own thinking while he is doing it, thus cutting possibly in half the volume of consciousness accompanying his mental activity. Eventual physical fatigue is inevitable, of course, as a result of muscular fatigue products generated in the course of strenuous exercise or work; but the tirelessness of a well-trained and hardened body is amazing when the muscular tasks undertaken are regarded as mere matters of course, and are performed, as far as the subject can tell, unconsciously. The endurance feats of the American Indian, and the astonishingly continuous exertions of the pioneer type of person, in all lands, are illustrations in point. Where much consciousness is, there much fatigue will be, also; and the limits of endurance of unconscious activities, of all sorts, are difficult to determine.

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7. The more conscious a reaction is, the more variable is the threshold value of its stimulus.

Another easily observable effect which consciousness seems to have upon responses to which it attaches is to render less predictable the exact intensity of environmental stimuli necessary to bring about the reactions in question. Simple reflex reactions can usually be evoked by physical stimuli of approximately the same intensity. There is a margin of variability even here. The knee jerk, for example, as^Carlson 1

finds, shows marked increase of excitability, with presumable lowering of threshold stimulus intensity, during strong hunger contractions of the empty stomach. Nevertheless, even the difference caused by hunger pangs in the stimulus intensity necessary to call forth the patellar reflex, could not be measured outside the physiology laboratory.

1 A. J. Carlson, The Control of Hunger in Health and Disease, p. 85, Chicago, 1919.

Activities more complex than the simple reflex but still reported to be unconscious are definitely conditioned upon a specific intensity of stimulus. The unconscious response to the legend naming the destination of the street car or 'bus may frequently fail to occur if the electric illumination of the sign be reduced only slightly. Persons frequently fail to stop a street car because the letters of the legend on the front of the car are smaller than those to which they have accustomed themselves to respond. Machine operators who depend upon a certain sound in the machine they are operating to set off a reaction* of shifting gears, may fail to perform the required net if the sound has slightly less than the customary volume. A housewife, using an electric coffee percolator, and depending for a signal that the coffee is done upon a certain sound made by the bubbling water, may fail to turn off the electric current at the proper moment if the crucial bubbling sound be less in tense than usual.

On the other hand, where the activity is more highly conscious, it is impossible to name a fixed intensity of stimulus which will invariably set off a given reaction. Consider, for example, responses which necessitate a great deal of consciousness such as a decision to play tennis or to take a two hundred mile automobile ride. Upon one occasion a normal subject may assent immediately to a casual suggestion that the tennis be played or that the trip be undertaken. Next day, perhaps, no amount of persuasion or even moderate financial inducement would evoke the reaction bf playing tennis or driving the car. Should these very reactions become habitual, as a part of the subject's professional duties or principal life activity, his consciousness concerning the actions would be tremendously reduced, also the margin of variability of the intensity of stimulus to which he responded. Again, it is necessary to call attention to the fact that we are not considering at the moment the psycho-neural mechanisms by which these differences are brought about. The significant point seems to be that when a large amount of consciousness attends a given response it may be evoked at one time by a stimulus of very low intensity and at another time it may require an exceedingly intense stimulus; while if an action is habitual or " unconscious " it is brought about upon all occasions by stimuli of nearly equal intensity,.

8. The more conscious a response is, the more readily it can be inhibited.

Highly conscious actions are more easily susceptible to inhibition than are responses carrying little observable consciousness. A love response, for example, which may have occupied the consciousness of a young woman for many days or weeks, is frequently completely inhibited by a chance frown or impatient gesture, on the part of the loved one. The most fiercely aggressive purposes of an adult human male, carrying with them both prolonged and intense consciousness, may similarly be interrupted easily by inhibition at a crucial point, even though the intruding stimulus be of no greater intensity than the disapproval of a partner or the absence from the city of another individual concerned in the enterprise. On the other hand, habitual responses such as walking or finding one's way to one's place of business through crowded traffic of a great city, may fail to be inhibited or impaired in the slightest degree even by the most intense variety of stimulus such as business failure, or the loss of a loved member of one's family. They are inhibited only when brought into consciousness by the loud honk of an approaching motor. If an adult eats food with his knife, he can only overcome such a fixed habit by making himself fully aware of his act every time he performs it. If ^person is performing a task which requires him to think out every move, a single suggestion on the part of another may suffice to* inhibit the response altogether. Consciousness, then, seems to be associated with ready inhibition of response.

9. The more conscious two or more responses are, the more they tend to facilitate or to interfere with one another.

There is, we find, another characteristic propensity of conscious behaviour which very closely resembles the ease of inhibiting just considered. Reactions of a simple refl& type to which little consciousness is attached do not seem to be

markedly influenced by other responses which may happen to be simultaneously taking place. Highly conscious reactions, however, are readily facilitated or impeded by the addition of further conscious elements of behaviour. An interesting experiment, frequently performed by students of psychology, is to train oneself to write automatically while performing arithmetical sums, or while carrying on trivial conversation

with another person. When this ability has been acquired, we have a situation where two reflex processes, each as slightly conscious as it is possible to make them, proceed simultaneously without any observable influence one upon the other. Similar effects of the same sort are found in every day life. A person with very little social training can converse readily on superficial subjects, while dropping sugar or lemon in his tea. An automobile driver is required to manipulate the wheel with one hand, turn on the lights, perhaps, with the other hand, regulate the accelerator by pressing down with his right* foot, and let in trie clutch by raising his left foot from the floor of the car. Frequently he must perform all these actions simultaneously and without mutual influence one upon the other.

What happens when the response is necessarily accompanied by a great deal of consciousness ? Suppose that a couple ol research students are deep in discussion of the apparatus required for a given experiment. Another student brings into the room a piece of apparatus which he has used in his own

work. Inspection of his apparatus requires the initiation of a new and complicated group of reactions on the part of both students concerned in the original discussion. Yet their inspection responses will be sure to combine in some way with the discussion already going forward. The new apparatus may harmonize with the plans tentatively evolved. In that case a very noticeable increase in the vigour and vglume of the discussion will immediately occur. Or, as the apparatus is inspected, it may present hitherto unsuspected difficulties in the procedures under consideration. In that case the new set of reactions produced conflict with the preceding responses, the conflict manifesting itself to the casual observer in the form of hesitation, argument, and disagreement. There is little likelihood that inspection of the newly-presented apparatus can proceed simultaneously with the preceding discussion or that it even can alternate with this discussion without influencing it by way of facilitation or conflict or both. When responses already going forward attach to themselves much consciousness, it usually will be found impossible to undertake a new set of conscious responses simultaneously. If the super-added reactions fail to inhibit the preceding conscious behaviour altogether, which is always likely, the new reactions cojnbine with the old either by enhancing their efficiency

)r by introducing obvious conflicts. Whether this result is iue to what has traditionally been called " increase of associative connections " pari passu with increase of consciousness, :>r whether it is to be explained by some more explicit neurological mechanism, the fact remains that the more conscious my two reactions are, the more likely they are to inhibit one

another, to facilitate one another by alliance, or to diminish

one another's efficiency by conflict..

10. The more conscious a response is, the more easily it is abolished or enhanced by drugs.

Highly conscious responses may be abolished completely by the use of drugs, while reflex reactions of low order involving Little consciousness proceed with only slight diminution under moderate dosages of anaesthetic. In taking ether, the responses carrying the largest amount of consciousness are first abolished. The " unconscious " reactions proceed substantially undiminished after the patient has taken all the anaesthetic he is able voluntarily to inhale.

Other drugs, such as various forms of morphia and Indian hemp, in certain appropriate dosages, produce tremendous enhancement of the most highly conscious reactions while having a negligible effect upon the more unconscious types Df behaviour. The highly imaginative writings of DeQuincy triay be cited as examples of intensely conscious responses greatly enhanced, according to DeQuincy 's own report, by appropriate drugs. These same drugs at advanced stages of their influence upon the body may abolish or inhibit the habitual reactions, also; but the first effect to appear as well as the most quantitatively marked influence seems to be exercised upon the most highly conscious activities of the subject.

W. W. Smith has shown 1 that moderate doses of alcohol produce what he calls an " all or none " effect upon the emotional responses of his subjects. That is, the highly Affective

reactions carrying with them a great deal of consciousness require a much more intense stimulus to set them off. When, however, these highly conscious responses are evoked, their intensity is out of proportion to the intensity of the stimulus. We have already noted that conscious emotions were subject to greater variability of effective stimulus intensity and also to less close correspondence with stimulus intensity than are

1 W. W. Smith, The Measurement of Emotion, ch. viii., p. 124. *

the little conscious, or " unconscious " responses. Smithes work, therefore, seems to indicate that the influence of small amounts of alcohol is markedly apparent in those responses to which is attached the larger amount of consciousness. Drugs, then, whatever be the direction of their effect upon the body, appear to exercise their influence more clearly upon the reactions involving most consciousness.

In summary, there are ten easily observable objective changes in human behaviour appearing Simultaneously with the reported increase of consciousness, namely :

1. Logger period between application of the physical stimulus and appearance of bodily response.

2. Persistence of bodily responses after the physical stimulus has been removed.

3. Less correspondence between the temporal rhythm or intervals manifest in the reaction, and the time intervals at

which the environmental stimulus is received.

4. Less correspondence between the intensity of the final bodily response and the intensity of the stimulus.

5. Increased tendency for several stimuli, each too weak to arouse the response by itself, to add themselves together and jointly evoke the reaction toward which they tend.

6. Greater fatiguability.

7. Greater likelihood that the same reactions will occur, at different times, in response to stimuli of different intensity.

8. Increased tendency to be inhibited by stimuli of comparatively slight intensity.

9. Increased tendency to combine with, or to conflict with, simultaneously imposed responses.

10. Increased susceptibility to the influences of drugs. These ten behaviour variances, then, may be shown to

appear in human behaviour pari passu with the reported appearance of consciousness. Like the sparks from Ben Franklfn's kite-string they reveal a specific but as yet undescribed type of energy. Is this energy identical with consciousness ?

There is, of course, a logical possibility, not to be overlooked, that the effects noted may be ascribable to the same vitalistictype cause that simultaneously produces consciousness, instead of the effects being ascribable to consciousness itself acting as a vitalistic-type cause. Elaboration of this logical

issutf, however, is largely academic. All the effects noted

must be attributed, because of their positive nature, to some form of potent energy; and it is more of a philosophical than a psychological issue to decide whether this potent energy causes consciousness or is consciousness. The later form of expression seems, for scientific purposes, more simple and accurate.

If there exists, then, a describable form of energy somewhere within the human organism capable of influencing behaviour in the ways noted, and if this potent form of energy is always found appearing simultaneously with consciousness, we ma}' state, for psychological purposes at least, that lh form of energy thus discovered is consciousness. Should consciousness turn out to be an energy by-product of the primarily potent form of force producing effects enumerated, then we should find inevitably a new series of observable effects which the energy by-product, consciousness, exercises, both over the parent energy directly, or over the physical behaviour results supposed to be produced jointly with consciousness, indirectly.

Consider an analogous situation. During electrolysis of water, two sets of physical phenomena are readily observable the giving off of hydrogen gas, and the formation of bubbles on the electrodes. For a time, after the current is turned on, these two sets of changes run parallel to one another, and during that initial period the mistake might be made of attributing one phenomenon to the causal agency of the other,

instead of considering both as results of a common cause, the electric current. But, after a short time, the formation of bubbles interferes, slightly, with the passage of the current, so that the more bubbles are formed, the less hydrogen is given off. This change in relationship reveals, at once, that a common cause of both phenomena must be sought. So far as my own researches reveal, there is no indication of a change in the parallel relationship between symptomatic behaviour and consciousness, which might suggest that both are attributable to a common cause. In short, granted a complete correspondence between symptomatic behaviour effects, and the appearance of consciousness without subsidiary variance, there is strong likelihood that consciousness and the primarily potent energy cause of the behaviour symptoms are identical. When the nature of this energy is discovered, it can definitely be described, like any other form of energy.

Consciousness Is Not Intra-neuronic Energy

What, then, is the nature of this conscious-energy ? Where is it to be found ? The simplest suggestion, in answer to these questions, seems to be that consciousness, in its physical aspect, is merely intra-neuronic energy. When physiologists, who naturally tend toward this hypothesis, are asked to account for the presence of much consciousness in some responses, and little or no consciousness in others, they^reply that only in

the more highly evolved portions of the bVain is there a sufficient accumulation of nervous energy, or a sufficient intensity, or some other attribute ol nervous energy, to produce consciousness. A few theorists may, perhaps, suggest that somewhere in the brain is a special kind of nerve cell capable of manufacturing conscious energy; but, so far as reported to the literature, no new type of brain cell, differing basically from neurones in other parts of the central nervous system, has been discovered. Such a suggestion, therefore, represents sheer imaginative speculation, and need not be resorted to until all known sources have failed to yield a trace of identification of any known form of energy with consciousness. What, then, of the physiologist's proposition that a sufficient mass of nerve impulses, per se, may constitute consciousness ?

Does nerve trunk conduction actually correspond with consciousness ? There are many difficulties in the way of such a theory.

First, and most important, we find that the teij types of effect upon human behaviour enumerated above as probable results of consciousness, do not find their physical basis in intra-neuronic phenomena at all. They are, rather, attributable to synaptic influence. The ten varieties of end -effect mentioned, together with several other similar effects, are listed by Sherrington 1 as inhering in reflex-arc conduction only, and not in simple nervetrunk conduction at all. Sherrington further Ishows that the salient characteristic of reflex conduction is the fact that synapses are interposed in the total nerve impulse circuit. It is at these synapses that phenomena occur producing the effects reviewed. That is to say, the fewer synapses in any nervous circuit, the less prominently may we

expect the effects which we have seen to be typical of consciousness to appear.

1 C. S. Sherrington, The Integrative Action of the Nervous System, p. 14:

The simple reflex acts, characterized by least consciousness, would contain, on the other hand, by far the greatest proportion of intra-neuronic disturbances, or simple impulses of conduction within the nerve trunk, and by far the fewest synapses. If these nerve trunk impulses truly constitute consciousness, as some physiologists maintain, there is a complete contradiction between evidence and theory. Where least consciousness actually appears, the greatest proportion of nerve trunk activity is to be found, and vice versa. It seems impossible, therefore, to define consciousness as the totality of changes, or energy within simple nerve tisSue, since this does not contain the mechanisms for the effects most characteristic of consciousness in our every-day experience.. In the second place, the same nerve trunks may be used for several purposes, that is, to convey impulses ultimately associated with two or more diverse varieties of consciousness. By the all-or-none law, each nerve fibre must respond in toto if it reacts at all. If, then, different units of consciousness ultimately appear due to ultimately diverse paths over tiny lengths of nerve trunk in the brain, could they escape marked resemblances, one to the other, when the greater portion of

their purely intra-neuronic constituents had been identical ? Pain impulses, for example, seem to travel during the first part of their circuit, at least, over identical sensory neurones with cold, pressure, auditory, visual, and many other types of afferent excitations, modally distinct in consciousness one from the other.

This point 1 has been adversely criticised by A. Forbes, 8 of Harvard Medical School, who cites the work of Adrian and Zotterman. C. J. Herrick,' however, states, " From this it would appear that most sensory nerves may, upon occasion, function as pain nerves." Herrick holds that the painful quality of consciousness is superadded to the ordinary sensory consciousness of the receptor apparatus stimulated, unless the stimulation is excessively strong ". Moreover, according to both physiological and psychological theories of vision, and other senses, excitations ultimately producing different sensations may originate in the same sense organ, thus making the

1 The argument under discussion was advanced more briefly by the writer in " The Paychonic Theory of Consciousness," fourn. Abnormal and Social Psychology, July, 1926.

* In a letter to the writer.

8 C. J. Herrick, Introduction to Neurology, 1920, p, 277.

long, afferent conductor paths to the higher centres identical.

But no part of this identity seems to be left in the final sensory consciousness.

On the motor side, the term, " final common path ", speaks for itself. All motor impulses must travel final common paths with impulses originating from many different sources, so that all must have large identical elements of intra-neural excitement. Physiologists, to be sure, might attempt to avoid this further problem by denying the existence of such a thing as motor consciousness altogether, even though, in so doing, they introduce an inconsistency into their conception of consciousness by maintaining that half the nerve impulses of the body (motor nerves) are not conscious, while the other half (sensory impulses) are conscious. Without pursuing further, at this time, the arguments for and against motor consciousness, we may emphasize the fact that the lack of similarity in various sensory elements of consciousness initially employing identical afferent nerve paths still stands as evidence against the physiological theory that nerve-trunk excitement is consciousness.

In the third place, different neurons appear frequently to be used in manufacturing identical elements of consciousness. Centrally aroused sensation such as, for example, " memory " of the colour red, or of muscle sensations in the legjs or arms, or of the tone of a violin, may be consciously no whit different from the originals of these remembered.sensations when the sensations were evoked directly by environmental stimulation of appropriate sensory nerves. Yet we know that nervous impulses cannot travel backward down the afferent paths so that the actual nerve impulses responsible for the remembered sensations must differ greatly from the

intra-neuronic impulses which brought about the original sensations themselves. If consciousnass consisted of the actual totality of nervous impulses concerned, in each case, then a remembered red sensation might be expected to differ substantially from red sensations which resulted from nerve impulses travelling up the optic nerve. Granted that both environmentally aroused red and the remembered red sensation utilized the same final sensory paths in the visual centres of the brain, there would still be the entire amount of optic nerve trunk energy possessed by the original sensation but not by its memory. Is it probable to suppose that this added incre-

THE PSYCHONIC IHEORY OF CONSCIOUSNESS 43

ment of energy, if this energy were consciousness itself, would add nothing to the totality of consciousness in the original red sensation ?

This proposition might indeed contain greater probability were it not that the optic tract nerve trunks are of great length as compared to the microscopic lengths of conducting fibres in the higher centres of the brain. If each unit of nerve impulse energy is cQnscious, it is hard to see how the very short conductor tracts of* the cerebral centres could contribute a greater total amount of simple nerve impulse energy than could the long affeient nerve trunks; and it is still more difficult to guess how the relatively tiny conductor trunks in the brain could contribute enough nerve impulses to obscure altogether the quantity of intra-neuronic energy contribued by the

afferent nerve trunks. If, as previously noted, the presence of large identical units of nerve energy in the manufacture of different sensations does not make these different sensations in the least similar, no more does the presence of a considerable volume of nerve trunk energy in connection with a given sensation seem to cause the sensation to differ in the least from an identical sensation manufactured without a similar volume or locale of nerve trunk participation.

In the fourth place, although there seems to be a mnemonic factor intrinsic in the behaviour of a single neurone in forming habitual junctions with neighbouring cells 1 there clearly could exist no structural changes within the nerve itself which could actually constitute the process of functional conjunction, since this process by definition takes place in the synapse, externally to the intra-cellular protoplasms of all neurones concerned. Thus no train of consciousness could be consecutive or continuous, if it were regarded as being constituted by the changes within any nerve cell in a reflex arc, for whenever any nervous impulse passed from neurone to neurone the propagation of energy between the cells would be of a totally different nature 8 and so it would no longer be included in our

1 C. J. Herrick, Neurological Foundations of Animal Behavior, New York, 1924, p. 112.

2 C. S. Sherrington states : "... the intercalation of a trans - vcise surface of separation or rrembrane into the conductor must modify the conduction," and : "It (the synaptic membrane) would be

a mechanism where nervous conduction, especially if predominantly physical in nature, might have grafted upon it characteis ju3t such as those differentiating reflex-arc conduction irom nerve-tiunk> conduction." The Integrative Action of the Nervous System, p. 17.

definition of " consciousness ". Moreover, since all facilitations and conflicts between impulses seeking to use a common neural path must occur for the most part in the synapses between the antagonistic neurones and the cell which both sets of impulses are seeking to enter, such alliances and antagonisms could find no counterpart among " conscious " phenomena, were the latter confined to intra-neural activities. Yet frequently reported " feelings of conflict ", " conscious thwartedness ", and, on the other hand, "'relief " and " feelings of harmony " seem most probably to depend upon these very extrinsic relationships between opposed and allied nerve impulses which we have been considering.

Finally, we know that different rhythms of stimulation, simultaneously applied, and using the same final common path to evoke the same muscular response, do not interfere with each other or break up the existing rhythm of response. 1 This would indicate that two separate nervous impulses, though they may use the same neurones simultaneously, do not fuse or combine in any way within the conductor nerve cells. If this be so, then identification of " consciousness "

with intra-neuronic change would leave totally unaccounted for all those " psychological " fusions, alterations, and recombinations of " conscious " elements which are continually reported by nearly all observers. If such fusions actually do occur, as supposed, at the synapses, no possible change within the individual neurones in any reflex chain could ever give them " conscious " representation.

Consciousness is Synaptic Energy

We have seen, during the foregoing brief review, that there exist substantial objections to the definition of consciousness in terms ot nervous impulses. We have, therefore, the question still with us : What is consciousness ? Before discussing the intra-neuronic theory of consciousness, ten types of effect which consciousness seems to have upon human behaviour were mentioned. These ten types of influence were cited as proof that an active energy is generated somewhere in the human organism possessing the attributes of consciousness. During discussion of the first of our reasons for rejecting the intra-neuronic theory, the fact was disclosed that, although

1 C. S. Sherrington, The Integrative Action of the Nervous System, p. i&.

the ten types of conscious influence do not have their causal origin in nerve impulses of conduction, their origin is attributed by neurological authorities to whatever happens at the

synapse. Sherrington lists some thirteen of fourteen phenomena as characteristic of synaptic influence upon nerve conduction as follows 1 :

i latent period

2 after discharge

3 loss of correspondence between rhythm of stimulus and rhythm of end effect

4 interference with grading of intensity

5 temporal summation

6 fatiguability

7 variability of threshold value of the stimulus

8 inhibition

9 mutual facilitation and conflict of impulses (treated

separately in Sherrington 7 s original work) 10 increased susceptibility to drugs : also, irreversibility of direction of nerve impulses, marked refractory period, " bahnung ", shock, dependence upon blood circulation.

It will be noted that the first ten synaptic influences listed correspond to the ten influences consciousness exerts over human behaviour. It is quite easy, also, to discover close correspondence between consciousness and the other synaptic

influences mentioned. Such discussion of these further correspondences is omitted in order to avoid too technical an excursion into neurological subject matter.

While human reactions, from the simplest to the most complex, probably depend upon reflex arc conduction, each arc containing, according to Sherrington,* at least three neurones and, therefore, two synapses, the more complex the reaction, the more complex must be the reflex arcs involved. That is, the more synapses have to be passed in any response, tne more must be the synaptic phenomena under consideration. As the complexity of the arc is increased, the greater will be the volume of synaptic energy as compared to the volume of simple nerve trunk energy. And, as we have observed, the greater

1 C. S. Sherrington, The Iwtegrative Action of the Nervous System, p. 14.

1 "The reflex-arc consists, therefore, of at Jeast thre$ neurones," Sherrington, %bid t p. 35. *

46 JiMOJLlOWS OF JNUKMAL

the complexity of the reaction the more consciousness is to be found accompanying it. Simple reflexes and habitual actions are brought about by a maximum of nerve trunk energy and a minimum of synaptic energy. Simple reflex

responses contain little, or no, consciousness, which the subject himself can observe. Complex subjective responses involve a maximum of synaptic energy, and a minimum of nerve trunk activity. These are the responses which are uniformly regarded as containing a maximum amount of consciousness.

The intra-neuronic tlieoiy supposes that consciousness appears cnly in the higher centres of the brain, because in no other place is to be found sufficient concentration of nerve impulse energy which is regarded as a physical basis for consciousness. " The higher centres " referred to, however, are located in the grey matter of the brain, and the grey matter is characterized chiefly by the enormous number of synaptic connections which are there operative. The grey matter is, in fact, chiefly composed of microscopically small neurones, each forming a large number of synapses with many similar neurones. The cerebral centres, therefore, where some physiologists suppose consciousness to be, are composed almost entirely of synaptic junctures.

Granted that the physical basis of consciousness lies in tbe higher centres, made up chiefly of tremendous numbers of synaptic connections, this fact, together with the evidence offered that the effects of consciousness on human behaviour are also synaptic, lead to the conclusion that consciousness is to be identified with synaptic energy.

Concept of the Psychon, and of the Psychonio Impulse

" Synaptic energy " is, however, a somewhat vague term. Specific types of energy are customarily defined by describing the type of matter within which the energy in question takes its origin. " Matter " is a word that is somewhat out of

vogue, since it is now the fashion to conceive of matter itself in ultimate terms of energy. Nevertheless, if one understands by the word " matter " a form of energy so permanently established that it gives rise to a comparatively uniform sort of experience, it remains a very convenient word to use in a discussion such as the one we are now undertaking.

All physical science assumes that there is some sort of matter, moving. Description of any connected series of

changes in any form of matter and its movement may aptly be termed a study of its " behaviour " in that particular level of complexity. Physics seeks to present basic descriptions of the behaviour of matter in its most elementary forms, the proton and the electron, and to trace the behaviour propensities of larger material masses back to the interaction of proton and electron systems, within the atom. Chemistry begins where physics stops, and deals with the laws of behaviour of the atom and the molecule, each containing varying numbers of protons and electrons. Chemistry deals especially with the laws controlling the combinations of atoms and molecules into more complex forms of matter. Biology deals with the behaviour of still more complex matter units, usually called " living organisms " of various sorts. Biology includes botany, which describes the type of living organisms called " plants "; and zoology, which deals with another type of living organism called " animals ". Animals are matter-units

of such extreme complexity, that their component parts become subject matter for several specialized sciences. Physiology specializes in describing certain parts of the animal termed " bodily organs ", and their behaviour. Neurology selects matter-units called " nerves ", upon which the behaviour of many bodily organs largely depends, and attempts to describe the behaviour of these nerves or neurones. If, then, there exists no further type of matter-unit capable of modifying neuronic behaviour, psychology, for all I can see, is out of a job. Shomd I become convinced of this state of facts I should feel compelled to consider psychologists in the same relation to neurologists as are carpenters to architects, and I should, for my own part, try to escape the fixed limits of craftmanship by studying my way into the ranks of my immediate intellectual superiors.

But, if, as suggested, there exists still another sort of matter unit beyond the neurone, capable of undergoing iti, own particular series of changes called " conscious " or " psychical " changes, and capable of modifying, by these changes, the behaviour of neurones, then, and then only is psychology truly justified in assuming a definite place among the physical sciences by the side of physiology and neurology.

Neurologists inform us that a specific conductive structure does exist at the synapses in all types of nervous systems evolutionally above those of the coelenterates. " It is generally

4 8

Assignments of tKe Sciences

Dcscript/ons or the Behaviour or Eoc,rfc Unjfs or Progressive Levels of Complexity

Physics Profon-Eleclron

Figure i

admitted ", says Sherrington, 1 " that there is not actual confluence of the two cells together, but that a surface separates them; and a surface of separation is physically a membrane.... It would be a mechanism where nervous conduction, especially if predominantly physical in nature, might have grafted upon it characters just such as those differentiating reflex arc conduction from nerve trunk conduction. 1 '

" In most groups of animals above the coelenterates ",

says Herrick,* " the dells of which the nervous system is composed (or some of them) are related to each other quite differently from those seen in the mesh work of protoplasmic -strands which compose the nerve net... there is a membrane separating the neurones. The presence of such a barrier at the synaptic junction does not imply that the neurones are not in protoplasmic continuity, for the separating membrane itself is living substance. What it does indicate is that there is a change in the physico-chemical nature of the conducting substance at the synaptic barriers. Langley has termed this barrier ' junctional tissue ', and of its great physiological importance there can be no doubt."

Physiologists, then, agree that there exists a special type of matter unit at the synapse capable of giving rise to a special type of energy which differs, in essential respects, from the nervous impulse. Neurological authorities, however, are not in such close agreement concerning the physical description of this junctional tissue. In the case of the giant Mauthner's cells, synapses between these cells and adjacent neurones can be seen and studied under the microscope by means of preparations in which the material has been fixed and stained. G. W. Bartelmez originally reported 8 that the knob-like endings of the axone fibres of the eighth nerve were seen in contact with the surface of the adjacent cell. Bartelmez saw a distinct plasm, or membrane, over the root fibres; and, where the lateral dendrite was cut squarely, a smaller *aembrane could be distinguished around it. There is little delay at this synapse, yet Bartelmez found that two synaptic membranes forming a junction by contact with one another

1 C. S. Sherrington, Integrative Action of the Nervous System, p. 16.

2 C. J. Herrick, Neurological Foundations of Animal Behavior, 1924, pp. 104, 114, 115.

8 G. W. Bartelmez, "Mauthner's cell and the Nucleus Motorius Tegmenti," Jour. Comparative Neurology t 1915, vol. 25, pp. 87-128,

Figure 2 THE SYNAPSE (From Bartelmez, Jour, of Comp. Neurol.)

Uncrossed V3E

Capillary

Pen cellular Nef

^"Plasmic Membrane

-Lateral Dendrite

PART A. " The detail of the VHIth nerve endings, and pericellular net of the lateral dendrite of Mautlmer's cell, drawn from a single section of an adult Arneiurus brain fixed in osmic-Zenker and stained with iron hematoxylin... The section passes obliquely through the base of the lateral dendrite, and shows the bulb-like endings of the VIITth root fibres, and the fine meshed neuropil of the pericellular not on its surface."

Myelin 3heotK

Glia Cells

Uncrossed Eighth Root Fibr Lateral De.nd.rife

InferiorYenfrical Dendrite

SupenorVanfncal

PART B. " The right Mauthnor's cell from a young Ameiurus male, fixed In a formol-osmic-Zenker and stained with iron hematoxylln. A semidiagrammatio reconstruction of ten sections, 5/i thick, magnified 250 diameters, to show the relations of dondritoa and axone to the cell body and the two striking synapses of the cell, viz., the endings of the VHIth root fibres (Uncrossed VIII) upon the lateral dendrite, and the axone cap covering the medial surface of the cell. Only four of the cap dendrltes are shown."

had to be energized before conduction could continue through the recipient neurone. Marui, who used different fixing and staining solutions, reported, 1 on the other hand, that he was able to trace tiny connective fibres emerging through the outer membrane of the club endings, and that he traced these minute, protoplasmic threads into contact, at least, with the adjacent neurone. Says Marui, " it is clearly shown that the intra and extra cellular neural fibres communicate with each other ".

Bartelmez, in still a later paper 8, criticized Marui's technique on the ground that he had used formol in the staining solution,

and that the use of this fixative was responsible for the false appearance of intercellular fibres. Such connecting filaments, Bartelmez regards, therefore, as arte-facts. Sherrington 8 in a recent citation propounds a theory of synaptic phenomena which seems to assume the existence of a membrane similar to that described by Bartelmez. Forbes, 4 on the other hand, has propounded a theory of the synapse based upon the idea that the various synaptic phenomena are results of nerve impulses in adjacent neurones being compelled, at the synapses, to communicate their energy through intercellular fibres of much smaller dimensions than the nerve trunk fibres. This view would be in accord with Marui's description of the physical appearance of junctional tissue, rather than with the view of Bartelmez. The exact structural description of the connective synaptic tissue must, it would seem, be left in some doubt for the present. I believe that it will make little difference to the theor}' of consciousness, herein proposed, whether the junctional tissue be thought of as a pair of sheet electrodes formed from the surface membranes of adjacent fibres, or whether the junctional tissue may eventually be described by comparison to the Tungsten filaments of electric lamps. Whichever observation may turn out to be most accurate, the evidence for placing consciousness at the synapse remains unchanged.

1 K. Marui, Jour, of Comparative Neurology t Vol. 30, pp. 127-158.

8 G. W. Bartelmez, " The Morphology of the Synapse in Vertebrates,'* Archives of Neurology and Psychiatry, Vol. 4, pp. 122-126.

8 C. S. Shemngton, " Remarks on Some Aspects ot Reflex Inhibition." 1925. Proc. Royal Soc., VCII, 519.

A. Forbes. " The Interpretation of Simple Reflexes in Terms of Present Knowledge of Nerve Conduction," Physiological Reviews, Vol. II, No. 3, July, 1922, pp. 361-414. p

In view of all the evidence, I submit the suggestion that the totality of energy generated within the junctional tissue between any two neurones, whenever the junctional membrane is continuously energized, from the emissive pole of one adjacent cell to the receptive pole of the next, intrinsically constitutes consciousness.

In expounding this theory during lectures, I have found it very convenient to employ a single term descriptive of any particular unit of junctional tissue which may be under discussion. Neurology, the science of nervous behaviour, dubs its structural unit the "neurone". Following this analogy, I have ventured to term the structural unit of psychology, which, as a science, must surely undertake the study of " psychical " or " conscious " behaviour, the " psychon ".

Propagation of energy upon any psychon, or unit of junc-

tional tissue, is definitely dissimilar in nature to the passage of nervous energy through individual neurones. Following the neurological analogy to its logical completion, therefore, we may term any wave of physico-chemical excitation initiated within a psychon, a " psyihonic impulse ".

It is clearly established by neurologists that the principal function of the neurone is conduction. It is my suggestion that the principal function of the psychon is consciousness. Whatever conduction of energy may occur across a psychofi seems incidental to the modifying major effect of impeding, regulating, and generally psychon's that energy in the course of its passage. The Tungsten filament in an electric light bulb conducts, to be sure, a certain amount of electrical energy from electrode to electrode; but the principal function of the filament is, nevertheless, illumination. Thus, while we may probably regard the psychon as a certain sort of conductor of inter-neuronic energy, we may adequately describe its chief property only, I believe, as the generation of consciousness.