LECTURE VIII
THE UNCONSCIOUS
Our studies up to this point have led us to the general conclusion that a large measure of the experiences of life are conserved or deposited in what may be called a storehouse of neurographic dispositions or residua. This storehouse is the unconscious. From this storehouse our conscious processes draw for the material of thought. Further, a large amount and variety of evidence, which we have briefly and incompletely reviewed, has shown that conserved experiences may function without arising into consciousness, i.e., as a subconscious process. To what extent such processes take part in the mechanism of thought, contribute to the formation of judgments, determine the point of view and meaning of ideas, give direction to the stream and formulate the content of consciousness, and in particular conditions, by a species of translation, manifest themselves consciously as phenomena which we designate abnormal constitute special problems which require to be studied by themselves.
Physiological memory and processes.—There is one phase of the unconscious which for the sake of completeness ought to be touched upon here, particularly as it is of considerable importance in any biological conception of intelligence. There is every reason to believe that intrinsically there is no essential difference between those physiological dispositions and activities of the lower nervous centers (subcortical ganglia and spinal cord), which condition and determine unconscious behavior, and those dispositions and activities of the higher centers—the cortex—which condition and determine both conscious and unconscious behavior. The former are undoubtedly innate in that they are primarily conditioned by inherited anatomical and physiological prearrangements of neurons and the latter are pre-eminently acquired through experience although probably not wholly so. (Our knowledge of the localization of function in the nervous system is not sufficiently definite to enable us to delimit the localization of either innate or acquired dispositions.) The innate activities of the lower nervous centers so far as represented by movements can be clearly differentiated from those of the higher centers and recognized in the behavior of so-called “spinal” animals and of animals from which the cerebral hemispheres have been removed. In the former the connection between the spinal cord and all parts of the nervous system above having been severed, whatever movements are executed are performed by the spinal cord alone and therefore of course by unconscious processes. The latter animals, although their actions are more complex and closely approximate (with important differences) those of normal animals, are also devoid or nearly devoid of consciousness. I say “nearly devoid” because in the interpretation of the experiments it is difficult to disprove that, as some hold, elementary sensations—qua sensation—are retained, though others regard the animals as purely unconscious physiological machines.
In the spinal animal, in response to specific stimuli, various movements are elicited which though of a purposive character are effected, as has been so admirably worked out by Sherington, by complex spinal mechanisms of a reflex character. The so-called “scratch reflex” and the reflex movements of walking, trotting, and galloping (the animal being suspended in air) are examples. Such reflexes involve not only the excitation of certain movements appropriate to the stimulus but the inhibition of antagonistic muscles and reflex movements. Further in the integration of the spinal system, reflexes are compounded, one bringing to the support of another allied accessory reflexes so that various coöperative[coöperative] movements are executed. A constellation of reflexes leads to quite complex spinal mechanisms responsive to groups of stimuli acting concurrently and resulting in behavior which is purposive and adaptive to the situation. The neural processes executing such movements are necessarily conditioned by inherited dispositions and structural arrangements of the neurons.
In the animal from which the cerebral hemispheres only have been removed there can be little doubt that the physiological mechanisms governing behavior differ only in complexity, not in kind, from those of the spinal reflexes; that in passing through successive anatomical levels from the spinal animal to this decerebrate animal with the addition of each successive ganglion the increasing complexity of behavior corresponds to increasing complexity of mechanisms or compounding of reflexes. And yet in the decerebrate animal without consciousness, as we must believe (excepting perhaps elementary sensations), the subcortical ganglia and spinal cord continue to perform exceedingly complex actions ordinarily, as we suppose, guided in the normal animal by consciousness. The reptile crawls; the fish swims; indeed the lancet fish has no brain, all its functions being regulated by its spinal cord. The frog hops and swims; the hen preens its feathers, walks and flies; the dog walks and runs. These, however, are the simplest examples of decerebrate behavior. Indeed it may be quite complex. The more recent experiments of Schräder on the pigeon and falcon and Goltz and Rothmann on the dog, not to mention those of earlier physiologists, have shown that the decerebrate unconscious (?) animal performs about all the movements performed by the normal animal.[[123]] “A mammal such as a rabbit, in the same way as a frog and a bird, may in the complete or all but complete absence of the cerebral hemispheres maintain a natural posture, free from all signs of disturbance of equilibrium, and is able to carry out with success at all events all the usual and common bodily movements. And as in the bird and frog, the evidence also shows that these movements not only may be started by, but in their carrying out are guided by and coordinated by, afferent impulses along afferent nerves, including those of the special senses. But in the case of the rabbit it is even still clearer than in the case of the bird that the effects of these afferent impulses are different from those which result when the impulses gain access to an intact brain. The movements of the animal seem guided by impressions made on its retina, as well as on other sensory nerves; we may perhaps speak of the animal as the subject of sensations; but there is no satisfactory evidence that it possesses either visual or other perceptions, or that the sensations which it experiences give rise to ideas.”[[124]]
Even spontaneity which at one time was supposed to be lost it is now agreed returns if the animal is kept alive long enough. It “wanders about in the room untiringly the greater part of the day” (Loeb).
Of course there are differences in the animal’s behavior when compared with normal behavior, but these differences are not so easy to interpret in psychological terms. Loeb, apparently following Schräder, does not believe the animal is blind or deaf or without sensation for it reacts to light, to noise, to smell, to tactile impressions, etc. It avoids obstacles and is guided by visual impressions, etc. The falcon jumps at and catches a mouse introduced in its cage; the dog growls and snaps if its paw is pinched and endeavors to get away or bite the offending hand; the pigeon flies and alights upon a bar, apparently visually measuring distance, and so on. But though it is guided by visual and other sensory impressions, does it have visual, auditory and other images, that is, conscious sensory states? This is not easy to answer. It certainly acts like an animal that is not blind nor deaf nor without tactual sensation, and yet it is conceivable that it is guided simply by sensory mechanisms without conscious sensation. The main reason, apparently, for believing the animal to be without sensation, as some believe (e. g., Morgan) is the absence of the cerebral cortex in which alone sensation is believed to be “localized.” Recently Rothmann[[125]] has succeeded in keeping alive for three years a dog from which the entire cerebrum was extirpated. It was then killed. Although the dog, like Goltz’ dog, in its behavior exhibited an abundance of functions in the spheres of mobility, sensibility, feeding, barking, etc., Rothmann came to the conclusion that it was blind and deaf.[[126]] Although apparently without taste for bitter, sweet, sour, and acid, yet the dog reacted differently to edible and non-edible substances, swallowing the former and rejecting the latter (moist sand); raw flesh was eaten preferably to cooked flesh and Goltz’ dog rejected from its mouth food made bitter with quinine. Some kind of gustatory processes (probably purely reflex as in Pawlow’s association experiments) were therefore retained though not necessarily taste as such. But blindness and deafness in the dog cannot negative the retention in birds and other animals of visual and auditory impressions of some kind which guide and originate behavior. But whether such impressions are psychologically sensations or not, the animal certainly does not possess visual or other perceptions, because the “sensations” have no “meaning.” Schräder’s falcon, for example, would jump at and catch with its claws a moving mouse in the cage, but there the matter was at an end; it did not devour it as would a normal falcon. Any moving object had for it the same meaning as a mouse and excited the same movement. So the decerebrate dog does not distinguish friend from stranger and other dogs have no meaning for it. All objects are alike to all decerebrate animals. In the popular language of the street “all coons look alike” to them. In other words the main defect is loss of memory for conscious experiences, of what Loeb calls associative-memory, the conscious memory which gives meaning to sensations, transforms them by synthesis into perception of objects and gives still further meaning to the objects. Hence for the pigeon without its cerebrum “Everything is only a mass in space, it moves aside for every pigeon or attempts to climb over it, just as it would in the case of a stone. All authors agree in the statement that to these animals all objects are alike. They have no enemies and no friends. They live like hermits no matter in how large a company they find themselves. The languishing coo of the male makes as little impression upon the female deprived of its cerebrum as the rattling of peas or the whistle which formerly made it hasten to its feeding place. Neither does the female show interest in its young. The young ones that have just learned to fly pursue the mother, crying unceasingly for food, but they might as well beg food of a stone.”[[127]]
One of the chief utilities of conscious memory is the means it offers the psycho-physiological organism to make use of past experiences to adapt present conduct to a present situation. This the brainless animal cannot do. Hence it is a mindless physiological automaton. All the actions performed by it, however complex they may be, are unquestionably performed and primarily conditioned by inherited neural arrangements and dispositions. They may be even regarded as complexly compounded reflex processes similar excepting in complexity, as Sherrington has held, to the mechanisms of the spinal cord. The behavior of the animal is therefore by definition instinctive. But even so this fact in no way throws light upon the intrinsic nature of the physiological process, but only upon the conditions of its occurrence. Acquired behavior is also conditioned—conditioned by acquired dispositions. The difference physiologically between the two is that in instinctive behavior the neural processes are confined to pathways established by evolutionary development, and in acquired behavior to pathways established by experience. Both must be conditioned by pathways, and the process in its inner nature must be the same in both. Many cortical processes, to be sure, are conscious—i.e., correlated with consciousness—but probably not all. And this quality of consciousness permitting of conscious memory is of great utility in the organization of acquired dispositions that provide the means for the adaption of the animal to each new environmental situation.
Furthermore, it is not at all certain that the behavior of the decerebrate animal is not in part determined by secondarily acquired dispositions. In the normal animal instinctive actions become modified and perfected after the very first performances of the act by conscious experience[[128]] and it is not at all certain that dispositions so acquired and essential for these modifications are not conserved and incorporated in the unconscious neural arrangements of the subcortical centers. So far as this may be the case the acquired modifications of instinctive behavior may be manifested in the actions of the decerebrate animals. In other words, the unconscious processes of the lower nervous centers motivating movements (and visceral functions) may include acquired dispositions or physiological memories.
That the subcortical centers are capable of memory seems to have been shown for the first time by Rothmann’s dog. This mindless animal proved to be capable of a certain amount of education. It learned to avoid hitting against objects, and to do certain tricks—jumping over a hurdle and following on its hind legs a stool upon which its fore feet were placed as the stool was dragged forward. “In the perfection of all these performances the influence of practice was easily recognized.” This means, if the interpretation given is correct, that new dispositions and new connections may be acquired within the lower centers without the intervention of the integrating influence of the cortex or conscious intelligence.[[129]] This is an important contribution for apparently the attempt to educate brainless animals had not been previously made, and their capability for education demonstrated.