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PART III

CHAPTER V

THE PSYCHIC MINIMUM

THIS economizing is by no means an endless process; there is a certain minimum of consciousness beyond which the psychic states cannot pass. This minimum of consciousness once reached, must remain stationary, for a fall below it is the arrest of the activity of that aggregate. In other words, there is a certain minimum below which consciousness cannot be reduced with impunity. Reduce the consciousness of the total psychic state by lowering the sensibility of its constituents or by raising the threshold of consciousness and the whole aggregate will cease to function. Diminution of the stimulus to which the aggregate has adapted itself in the course of its growth, both phylogenetic and ontogenetic, gives the same results; the aggregate does not respond. Either a summation of successive small stimuli or an intense stimulus that should reach the threshold is requisite to set the aggregate into activity. In short, a minimum of consciousness is always required for the proper functioning of mental aggregates.

            This condition of minimum of consciousness requisite for the proper function of lower mental aggregates is clearly seen in different forms of pathological cases.

            In the initial stages of tabes, when the kinaesthetic sensations of the feet and legs become hypoaesthetic, the patient is unable to walk well and must be guided by visual sensations, so that when his eyes are closed, he stumbles. Although he may feel that his limbs were moved, if the movement is quick and thorough a considerable angle, so that the stimulus is intense, he still does not know the direction of the movement, nor is he aware of the position of the limb when left to itself. Similarly in cases of onset or slowly recovering hemiplegia, the sensibility falling below the requisite minimum produces a total failure in the sensori-motor adjustments by means of content coming from the visual sense.

            As a good illustration of the point in question, I may mention a very interesting case of my own now under investigation. The patient suffers from tactile anesthesia all over the trunk, with the exception of neck and face and lower extremities; the other sensations, such as those of temperature, pain, pressure, muscular sense and kinaethesis, are greatly diminished. The patient does not feel one short, sudden stimulus, such as a prick, pinch, burn, but only a long continuous stimulus, or a quick succession of more or less intense stimuli. The patient is unable to adapt herself to the changes of external environment and often hurts herself, before she becomes aware of danger and is enabled to react and ward off the harmful stimulus. The aggregates with a reduced minimum of consciousness fail in their function and are unable to adjust themselves to the external environment.

            This failure to function in case of fall below the standard minimum is still further illustrated in the diminution of the patient’s muscular sensibility. If she is told to close her eyes, and her arm is taken roughly and given a quick and sharp wrench, she is aware of the movement and also of its direction. If, however, the same passive movement is produced slowly, gently, by degrees, then the patient is unaware, both of the movement and direction; even if the hand has been rotated in a circle or raised in a horizontal position from a position of repose close to the body, the patient thinks that the hand has not moved and is still in the same place. If now the patient is told to touch a part of her body, such, for instance, as the nose, eye, or ear, the attempt is often a failure, on account of the unnecessary extra amount of energy put forth in the muscular effort of bringing the hand in the required position. This extra amount of effort put forth is determined by the extent of hypoaesthesia and the false notion of the position of the arm.

            If the experiment is somewhat modified and the arm is raised a little faster, so that the patient becomes aware of the changed position, of the movement, but not of the direction, the results are no less interesting. If under such conditions the patient is asked to put the hand to the nose, eye, or ear, the answer is uniformly the same: “I cannot; I do not know where the hand is.” Once more the sensori-motor aggregate, with its lowered minimum of consciousness, fails to act and carry out its adjustments to its surroundings.

            A variation of the experiments leads again to the same conclusion. If the patient, with the hand at rest, is told to raise it, and when she starts the movement the hand is seized and kept forcibly, the patient, after making strained efforts finally declares that the hand is raised; the sensori-motor aggregate fails to act and make the proper adaptations.

            A further variation of the experiment reveals still clearer the paralysis of an aggregate with a lowered psychic minimum. If the arm is half raised and the patient, with the eyes closed, is told to raise it still higher, and as soon as the patient starts the movement the hand is seized and moved in a different direction, after some time she declares that the hand is raised, although the hand is in a much lower position than the original one. Once more we find that a lowering of the minimum of consciousness of a psychic aggregate brings about a complete failure of adjustment and is equivalent to a paralysis of its function. A definite minimum of consciousness is the sine qua non of psychic aggregates.