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PART III

CHAPTER XI

THE THRESHOLD OF MENTAL LIFE

IN discussing the psychic minimum, it has been pointed out that there is a minimum of consciousness beyond which the moment cannot fall, if it is to work efficiently in its functions and adaptations to the conditions of the external environment. The arousal of such a psychic minimum depends on the general state of the functioning aggregate. Under certain conditions the state of the functioning aggregate may change so as to make it more difficult to arouse the requisite psychic minimum; on the other hand, the conditions may be of such a nature as to make the psychic minimum more easily aroused. Both sets of conditions indicate an abnormal state of the functioning aggregate.

            Under the influence of certain toxic stimuli, such, for instance, as alcohol, cannabis and opium, the psychic minimum becomes easily aroused, associations in certain directions are awakened with great rapidity. This is clearly illustrated in the many forms of autotoxic and bacterial maladies accompanied by high temperature and consequent inducement of maniacal-like states, such, for instance, as are to be found in malaria., typhoid fever, and so on. Still clearer is the same condition revealed in the many states of mental alienation characterized by maniacal attacks, such as are to be found in the various forms of mania, simple mania, recurrent mania, alternating mania, mania furiosa and other states, in which the so-called maniacal outbreaks are manifested. In all these conditions the psychic minimum is readily aroused, the aggregate of moments has become more sensitive, and hence more responsive to stimuli coming from the external environment.

            In other states the psychic minimum may be aroused with great difficulty. Such states may occur under the influence of depressive drugs, such, for instance, as the bromides, the later stages of the action of toxic and autotoxic agencies. The man in the stage of drunkenness is awakened with difficulty, the difficulty corresponding with the depth of the stage of intoxication. The patient in the later stages of high fever is in a state of stupor, a condition from which it is the harder to arouse him the more insidious and more intense the fever is. In idiopathic and the later stages of Jacksonian epilepsy, conditions which may be, characterized as to their disorganized chaotic motor discharges as “motor manias,” are often followed by states of stupor in which the arousal of the psychic minimum of the mental aggregate becomes nigh impossible.

            In the different forms of melancholia, such as simple melancholia, the recurrent and alternating forms, and especially in the states termed stuporous melancholia, this condition of fall of the psychic minimum, with consequent difficulty of arousal of the mental aggregate, is clearly manifested. In melancholia the flow of associative psychomotor activity is greatly impeded, and mental synthesis is effected with difficulty. Moments require a considerable length of time to reach the fullness of their development and their association with other moments is one of a slow, difficult and painful process.

            The fluctuations in the ease and difficulty of arousal of the psychic minimum of the moment aggregate are but approximately estimated in complex mental states. In the more elementary forms of moments they may be determined with more or less precision by the intensity and duration of stimulation required. When the arousal of the aggregate requires a stimulus of high intensity, then the psychic minimum is aroused with difficulty; on the other hand, when the mental aggregate requires for its arousal a stimulus of low intensity, then the psychic minimum is aroused with ease. The difficulty of arousal of the mental aggregate means a fall and impoverishment of the psychic minimum, while the ease of arousal or of stimulation of the aggregate means a rise of the psychic minimum. Now, it seems clear that when the functions of the mental aggregate are effected with difficulty, there is a fall of the psychic minimum and a rise of the intensity of the stimulus, and when there is ease of inducing functioning activity in the aggregate, there is a rise of the psychic minimum and consequently a fall in the intensity of the stimulus. The external stimulus and the psychic minimum stand in inverse relation to each other.

            If the activity of the functioning aggregate is regarded in relation to the stimulus, the two are found to be intimately related. A definite amount of stimulus is required before the aggregate can begin to function. A fall below that amount will fail to arouse the psychic minimum. Now that intensity of stimulus which is next to the one just sufficient to arouse the aggregate to functioning activity and give rise to the psychic minimum, may be termed the stimulus threshold, while the state lower than the minimum may be termed the moment threshold. In order that a moment or aggregate of moments should become in a condition to function, it must first overstep the psychic or moment threshold, attain the psychic minimum, while the external stimulus must overstep the stimulus threshold.

            The relation in which the thresholds stand to the psychic minimum is not the same in which they are to each other. The psychic threshold and the stimulus threshold are in direct relation. If a higher stimulus is required to awaken the psychic minimum, that indicates that both the psychic and stimulus thresholds have been raised. The same condition, however, shows that the psychic minimum has not increased. The thresholds and the minimum are not directly related. A rise of the thresholds is a fall of the psychic minimum, while a fall of the thresholds is a rise of psychic minimum. The thresholds and the minimum are in inverse relation.

            In the simpler forms of sensory experience, the stimulus threshold is found by measurements for the different senses. Thus two parallel lines are for most people barely distinguishable when the distance between them subtends an angle of less than 60 seconds. In the sense of hearing, vibrations recurring between 30-35 per second are barely distinguishable. Below 16 vibrations per second no sensation of sound can be produced. Thresholds have been similarly determined for all other sensations. Thus the sense of touch, when tested by the aethesiometer, which, by the way, is an extremely unsatisfactory instrument, gives the average for the tip of the forefinger about 1.65 min., on the back of the hand about 16.0 mm. Sensitivity to pain as tested by the algometer varies from 10° to 15°. Sensitivity to smell varies with different substances; thus for smell of garlic sensitivity varies in detecting 1 part in 57,000 parts of water to 1 part in 44,000 parts of water; for oil of lemon from 1 to 280,000 to 1 in 116,000. Taste can detect the bitterness of quinine in a solution of 1 part quinine to about 400,000 to 450,000 of water; the sweetness of sugar can be detected in a solution of 1 part sugar to 200 of water; the taste of salt can be detected in a solution of 1 part salt to about 2,000 parts of water.

            In the higher and more complex moments there is no possibility, for the present at least, to determine mathematically the amount of the stimulus threshold: but all the phenomena reviewed by us, as well as the analogy with the simpler moments leave no doubt that such a threshold and its correlative threshold of the moment consciousness play a very important part in the formation and interrelation of functioning complex moment aggregates.

            The moment threshold rises with the activity of the moment. The longer the duration of the activity of the moment the greater is the relative increase of stimuli, both in number and intensity, requisite to prolong the activity at the same pitch. As our work on a subject progresses, unless new points of view unfold, serving as new stimulations, our interest wanes and our attention lags. In fixating a point we find that more and more effort is requisite to keep it before our eye, and that it finally disappears. Something new comes within the field of vision.

            In the sphere of sensation we find the same rise of moment threshold. We are all acquainted with the fact that an additional candle or lamp, for instance, in a well-lighted room does not produce the same sensory effect as when brought into a more or less dark room. An electric light in the sun is scarcely perceptible. An additional ounce to a lifted pound does not feel as heavy as when raised by itself. A sound added to another sound or to a noise, sounds less loud as when appearing isolated, or when the same sound is breaking upon silence. The same relation holds true in the case of other senses. This same truth is still more clearly brought out in the fact that if we take a certain stimulus as a unit giving rise to a definite sensation, then as we progressively ascend and add more and more units of the same stimulus, the intensity of the sensation is far from rising proportionately. If we take, for instance, the weight of an ounce as our unit of stimulation, then the successive moments of unit-stimulations, that is, of ounces, will not give rise to as distinct and similar sensations as the initial stimulation. The second ounce will give a sensation fainter than the first one, and the third fainter than the second, and so on until a point is reached when the sensation of the additional ounce will not at all be appreciated, will dwindle away and almost reach the zero point. In the same way, if the pressure of a gramme is excited in the hand, successive increments of grammes will not in equal degree increase the sensory effect; the additional increments of grammes, though they are equal units of stimulation, give rise to fainter and fainter sensations, until finally all sensory appreciation of the added unit fades away and disappears. If the hand is immersed in water, say at the freezing point, an addition of ten degrees will be perceptibly appreciated, while successive increments of ten degrees each will be felt less and less, and finally will not be noticed and become difficult to detect. In short, the moment threshold rises with its stimulation. To bring about a sensory response of an already stimulated sense-organ the intensity of the stimulus must be relatively increased. This is what constitutes Weber’s law. The continuous progressive sensory response of a sense-organ requires a constant increase of stimulations which, within certain limits, bears a constant ratio to the total stimulus. This law is sometimes summed up by psychologists in the statement that “the increase of the stimulus necessary to produce an increase of the sensation bears a constant ratio to the total stimulus.” Activity raises the moment thresh old; it is the beginning of fatigue.

            The rise of threshold after stimulation holds true in the whole domain of biological activity. If the gastrocnemius muscle of a frog, for instance, is stimulated by an electric current, the muscle, with each successive stimulation, responds less readily with a contraction, and this becomes more evident with the onset of fatigue. Pffefer, in a series of extremely interesting experiments, has shown that spermatozoids of ferns are attracted by malic acid, the progressive response of attraction of the cell requiring a constant increase of the degree of concentration of the acid, the increment of stimulations, as in the case of sensation, bearing, within certain limits, a constant ratio to the total stimulus. The threshold rises with each successive stimulation.

            The rise of moment thresholds increases with intensity and duration of stimulation as we approach the state of fatigue. Through the influence of exhaustion, fatigue, or the influence of toxic, autotoxic, emotional and other stimulations, the thresholds of certain moments have been raised so that ordinary or even maximal stimuli can no longer call out any response of the moments. Now, when such a rise of moment thresholds is present, the moments with raised thresholds can no longer enter into association with systems of moments with which they are usually associated, and the result is dissociation, giving rise to the great multitude of phenomena of functional psychosis with a subconscious background, the extent of which depends on the number of raised moment thresholds, on the extent of the dissociation effected.

            When a moment or aggregate of moments begins to function it also radiates stimulations to other moments or aggregates of moments. All the aggregates which these radiated stimulations reach will not equally begin to function. It will depend largely on the state of the aggregate and its threshold. If the radiated stimuli be minimal, the many aggregates that have a high threshold will not be affected at all. Furthermore, many aggregates whose arousal could otherwise be easily effected by the given stimulus may temporarily be in a condition in which their thresholds have become raised and thus fall outside the sphere of activity of the functioning aggregate. On the other hand, aggregates that are usually inaccessible to those minimal stimuli may under certain conditions get into activity by similar stimuli through the previous lowering of the threshold of the total aggregate. Thus the aggregates set into activity by the functioning aggregate are conditioned by the rise and fall of their thresholds.

            In case where the threshold of an aggregate is raised, the radiating minimal stimuli coming from a particular functioning aggregate may become efficient and reach the threshold, when another aggregate begins to function simultaneously: This holds true even in the case when the minimal stimuli coming from two different aggregates are just below the threshold stimulus. Thus, under certain conditions, when visual stimuli are barely or not at all discernible, they can become intensified by re-enforcing them with auditory stimuli. This is commonly found in the fact of forgetfulness of a name or of some event and in the mode of its recovery. We try to find the name and seek to come to it in one line of thought, but of no avail; new lines are attempted, and finally the combined activity of the systems reach the lapsed aggregate whose threshold, through a lapse, the nature of which will be discussed afterward, has become temporarily raised.

            We find the same truth further exemplified in the case of the infant under my observation. When with the nipple in his mouth the infant ceased nursing, the sucking movements could be induced again by stimulating some other sense-organ. The tactile pressure, temperature and taste stimuli coming from the nipple in the infant’s mouth became insufficient to stimulate to activity the functioning aggregate of sucking movement on account of its raised threshold, and only additional stimulation could bring about a further functioning of the lapsed aggregate. This, of course, could also be effected by making the tactual and pressure stimuli coming from the nipple more intense, such, for instance, as shaking the nipple while the infant kept it in his mouth. This increase of intensity, however, mainly indicates that the stimuli were no longer effective, and an additional stimulus was requisite, a stimulus that might come either from the same aggregate or from a totally different aggregate.

            In the many cases of post-hypnotic amnesia, we find the same truth further illustrated. In the deeper stages of hypnosis, from which the subject awakens with no remembrance of what had occurred during the state of hypnosis the lapsed memories can still be brought into the upper consciousness by plying the subject with many questions. During the trance or during the intermediate stages, with subsequent trance and suggested amnesia, the subject is made to perform a certain action, to light and extinguish the gas four times in succession, or to open and close the door four times. The subject is then awakened from his trance; he remembers nothing of what has taken place. If he is asked point-blank whether he remembers any incidents of his hypnotic state, he answers with an emphatic negative. If now the subject is asked whether he knows how much two times two are or his attention is incidentally directed to the gas or to the door, he at once becomes reflective, the subconscious memories are on the way to surge up, and a few further indirect questions, the number depending on the depth of hypnosis, finally bring about the lost memories. The threshold that has risen at the end of the trance is stepped over by the combined effect of the many stimulations coming from different directions and the subconsciously submerged moment or aggregate of moments surges up to the focus or nucleus of the upper consciousness.

            Once a particular moment is stimulated in its appropriate way, it may go on developing, and usually does so by stimulating and setting into activity aggregates of moments associated with it, or may form new combinations of aggregates. The solution of a problem may present great difficulties, but once started on the appropriate line, the whole series of combinations goes on unfolding, stimulating other moments and aggregates and forming more and more complex combinations. Thus, Archimedes, as the story runs, while in the bath made discovery of the law of specific gravity. Newton under the apple-tree made the discovery of universal gravitation. Hughes was startled by the idea of symmetry in his discovery of the laws of crystallography. Goethe was led to his conception of metamorphosis and evolution by a skull on the plains of Italy. Darwin, by reading Malthus’s economical treatise on population, was inspired to work out the great principles of the struggle for existence and natural selection. Myers, led by the greater redness of blood in the blood-vessels’ tropical patients to his grand conceptions of transformation and equivalence of energy. All these examples ill irate the fact that once a moment has been started, it goes on developing by stimulating other cognate moments and aggregates to functioning activity.

            The same condition is also found in psychopathic borderland states, such as dreams. In dreams a peripheral stimulus gives rise to sensations that start the functioning of moments, which in their turn give rise to phantastic combinations combinations of different aggregates. This phantastic combination of aggregates, giving rise to the functioning of otherwise unusual, or what may be termed abnormal constellations, is largely due to the fact of redistribution of thresholds in the dream state. The dream state is characterized by a rise of the thresholds of the moments and aggregates that have been functioning during the waking states, the thresholds of these aggregates having been raised through fatigue. In such a state as this moments that have their thresholds relatively or absolutely lowered through rest, in other words, moments or aggregates that are unusual during the waking state, will become aroused and begin to function, hence the phantasms of the world of dreams.