Memory and the Brain

Magda B. Arnold

• Publisher: Psychology Press
• Year: 2013
• ISBN:
  9781134922819
• Edition: 1
• Topic: Psychology
• Subtopic: History & Theory in Psychology
• Index: Psychology

Published in the year 1984, Memory and the Brain is a valuable contribution to the field of Neuropsychology.

I	PSYCHOLOGICAL ASPECTS

1	Perception

Only recently have psychologists begun again to speak of direct perception as the basis of knowledge and a “valid and reliable source of information” (Turvey & Shaw, 1979). Unless we trust our perception, we cannot come to veridical conclusions about the world. As Turvey and Shaw point out, if we do not perceive what is really out there, all knowledge, necessarily based on perception, is suspect and no amount of reasoning or inference can make it valid. If perception is not veridical, it is inconceivable that animals could have successfully coped with their environment and evolved in it. While vision alone may deceive us, neither human beings nor animals depend on the information derived from a single sense.

PERCEPTUAL INTEGRATION

It is generally agreed that sensory experience depends on selective attention. The very word “stimulus” indicates that not everything in the environment will prompt a reaction. In any psychological experiment, conditions are so arranged that the subject will respond to the stimulus selected by the experimenter. In animal experiments, the animal usually has to be “shaped” before it will attend to the selected stimulus and give the desired response. To select and attend to one thing, it must be perceptible to our sense organs. It also must be sufficiently defined to stand out from its background.

Whatever the type of energy that impinges on the organism, whether electromagnetic, mechanical, or chemical, the sensory experience depends on the specific receptor organs stimulated. A single object may be experienced via different senses. We see a man playing the violin, hear the sound, can touch the violin and feel its vibrations. We know without any process of reasoning that the sound comes from the man playing the violin.

Individual senses cannot convey such integrated experience. All the sense of sight can do is mediate visual experience; the sense of hearing, auditory experience. Yet we see things, not patches of color, hear melodies, not single tones following one another. We touch an object and form a notion of its shape, rather than having discrete touch sensations. Sensory experience is integrated before we become aware of it. Such an integration of experience must be some kind of sensory function because it is unperceived, preattentive, as direct as all sensory experience.

A phrase coined by William James has it that the infant experiences the world as a “buzzing, blooming confusion.” If James meant, as some of his successors did, that the infant's world has no articulation, that objects must be established by moving toward them and manipulating them (Schilder, 1950), it is curious that he never explained how the child would ever manage to find the objects toward which to move. A visual field without any articulation, without up or down or side-by-side would make it impossible to single out anything for attention or manipulation. More than that, there is no reason in the world why the sense of touch, in manipulating something, should convey the notion of an object separated from other objects if the sense of vision cannot do so.

Much more likely, James meant that the infant's world has as yet no meaning, that the infant sees things but does not know what they will do to him or how he can cope with them. For such knowledge, he has to touch and manipulate them and find out how they will affect him. The memory of such experiences will then gradually make the world meaningful to him.

The integration and articulation of the environment into separate objects must necessarily occur before we experience anything. It must be a sensory function, completing the experience of seeing, hearing, touching; we could call it the function of an integrative sense, mediated, like sensory experience, by the cerebral cortex. In recent years, some “preattentive” perceptual integration has been postulated by theorists. So Johansson (1979) pointed out that seeing movement when a spot of light is directed successively at neighboring positions, presupposes an integration that is an immediate sense experience without any cognitive inference. And Allport (1979) assumes a preattentive visual integration. In the nature of the case, the existence of such an integrative sensory function must be inferred; it cannot be directly demonstrated because any conscious experience already contains the result of such integration. However, such integration can be prevented, either experimentally or as the result of brain lesions.

Thus Allport (1979) points out that conscious perception of a tachistoscopic array as words rather than as rows of squiggles is limited by the rate at which this perceptual integration can operate. And Faust (1955) has reported that patients experience a disintegration of form after occipital lesions. When such a patient looks at something for a short time, its form disappears; it may return if he looks away for a while. Usually, this disintegration of the visual field has been explained as abnormally quick fatigue of the visual apparatus after brain lesions. But if that were so, such disintegration should also be experienced without brain lesions when long periods of reading or close visual work result in fatigue. But normally, while increased visual fatigue may produce blurring or fiimmering, it never results in a disintegration of the total visual field. According to Faust, this disintegration failed to occur if letters or words were shown on a tachistoscope where each item is shown separately. Only when the patient tried to read a page of print did he seem incapable of coping with the task. Faust calls this impairment “spatial blindness” and says, “Characteristic for spatial blindness is the ‘loss’ of things seen, together with a continual seeking with the eyes, while the transition from one thing to the other becomes extremely difficult.”¹ From Faust's careful description it seems clear that this is a perceptual defect resulting in the impairment of visual integration, after damage to the primary visual cortex. In addition, the registration and recall of perceptual experience seems to be deficient as well. Faust points out that these patients are also unable to order things in imagination into a visual space. To imagine things in some side-by-side order, we need a visual memory schema. If it is missing, visual imagination cannot organize visual memory images.

VISUAL SPACE

Since Faust and other workers in this field often speak of “spatial ability,” it might be profitable to ask just what is implied in space perception. How do we see space? Is space, as Kant has it, a “condition of sensibility” that necessarily precedes all sensory knowledge? Or is it a special way of seeing, as Faust seems to imply?

Our notion of visual space implies that there is a certain order among the things that surround us, that they are spread out before our eyes. There is good reason to assume that depth perception is innate: the “visual cliff” is avoided by infants of many species before any learning can have occurred. This innate perception of distance seems to give us the first awareness that some things are near and others farther away. Similarly, there is a primitive knowledge (before any concepts are formed) that something is located to one side or another, in front or behind us, a knowledge that is acquired not only by sight but by hearing, touch, even smell, and is tested by every attempt to reach or avoid the things so experienced. Not every sensory modality can give us a precise notion of the location of things around us. We know that something we touch is close at hand, but we do not know exactly how far something is that we see or hear. But various cues (relative size, relative clearness, etc.) allow us to learn how to estimate distance more accurately. We innately perceive things ordered side-by-side and in depth; but the accurate perception of distance demands experience and memory.

When a man lacks sight, it is much more difficult for him to achieve a correct notion of the direction and distance of things in relation to himself, but it is possible with the help of movement and touch. People born blind are able to find their way around the house, around the neighborhood, and even around their district, with remarkable confidence. This surely means that they have formed a notion of the way things are arranged around them. They must have a map of their environment so that they can use spatial concepts without difficulty. Of course, their space is not a picture of things spread out around them but a structure of objects in various directions and at various distances from themselves, measured by the time it takes to walk to them.

Their space perception differs from that of the sighted, as shown by reports of people born blind who later gained their sight through an operation. When such a patient first opens his eyes, he seems to think that the things he sees are touching his eyes, and often covers them with his hand, afraid his eyes will be hurt. Senden (1932), who has collected many reports of such patients, emphasizes the difference in their space perception compared to the sighted. But he draws the unjustifiable conclusion that only vision can provide us with the notion of space. It is true that a man born blind has no perception of visual space; but it does not follow, as Senden claims, that the notion of space is inherent only in vision and can be formed from no other sense. If it were, a person born blind would not be able to move in space with confidence while blind, but should have normal space perception as soon as his vision was restored. Actually, some patients who have regained their sight find the effort required to move with eyes open too exhausting and never learn to use their newly acquired sense of sight for their daily tasks. What seems to have happened is that while blind they formed memory images of their environment on the basis of motion and touch. Because they have no visual memory of objects and their position around them, they are unable to recognize anything by sight or to move among the things they see.

Senden reports, for instance, that such patients did not recognize simple objects on seeing them. They could distinguish a circle from a square but could not say which was a circle and which a square. But when they traced the outline of both, they immediately knew their name, and ever after could recognize these two figures, no matter what size or color they were, or of what material they were made. Apparently, when blind, the patients had learned to recognize circle and square on the basis of tactual and particularly motor memory. Since the shape traced manually and so registered and remembered as a motor memory image had no connection with any visual memory image, merely seeing the two figures did not suggest the outlines the patients had traced and remembered. Once they had both seen and traced the two figures, and so connected the two experiences, they were able to recognize circle and square on seeing them.

It is curious how often we are misled by our linguistic habits. Because visual, tactual, motor, and conceptual memory normally work together, we speak of “memory” and assume that it is a single function, no matter what sense modality has produced it. When we are told that on gaining sight a man born blind cannot recognize a circle or a square although he can see that they are different, we assume that his difficulty cannot be a memory deficit because he still remembers the concept “circle” and “square” formed on the basis of motor and tactual experience.

Thus Senden assumes that the defect must be a “lack of space perception” supposedly inherent in vision. But once we entertain the notion that memory depends on various sense modalities that normally act in unison, it becomes plausible that visual memory requires the registration of visual impressions and their connection with memory traces from other modalities. We must see something and find out what it is called before we can recognize it by sight alone and repeat its name.

When sight can be used normally, together with all other senses, it will dominate our experience, not because of some mysterious “spatial” property of vision but simply because visual memory can be checked by moving about, in a way tactual memory cannot. Without sight, a person's notion of space is based on touch, hearing, and movement. The blind do not move, as Senden suggests, by calculating the distance and direction; if they did, they would never be able to move with assurance even among familiar things. They ate guided by the memory of the steps they have taken in walking toward something, or the movements they have made in reaching for something or tracing its outline. Such motor and tactual memory is not as efficient as visual memory. Using sight, a man can recognize landmarks before he comes to them and so can change his direction, if necessary, without retracing his steps. A person born blind certainly acquires a concept of space: he knows in which direction to move, and approximately for how long, before he can touch a particular piece of furniture. But because this spatial map is not a visual image, such a person will he intolerably confused on gaining sight until he has tried to move among the things he sees and by manipulating them has connected his tactual and motor memory with the visual images. This takes time and effort. It is not surprising that many people on gaining their sight as adults lose patience and prefer the familiar non-visual way—just as many people who become blind never manage to acquire a scheme based on touch and movement.

In short, Senden's explanation that space is an inherent characteristic of vision comes from first mistaking the visually ordered images of things for the concept of space, and next concluding that people born blind who have no such images cannot have a concept of space. They do have such a concept, but in their sightless days they had to derive it from touch, hearing, and moving, without the help of the visual perception of things arranged side-by-side, in front or behind them, which is the most important basis of the concept of space for the sighted.

CONSCIOUSNESS, MEMORY AND PERCEPTION

Every perceptual experience presupposes awareness; and awareness is impossible without memory. Our awareness includes not only the present moment but a stretch of time immediately before, what William James called the “specious present.” To be conscious means that we are aware of what goes on around us, that we sense, think, feel, can move and talk, that we can remember our immediate as well as our distant past, and reflect on our experiences. As Gasson says:

what is conscious must indicate some psychological experience, something lived through of which we know; a knowing or a wanting or a doing or happening in us of which we have direct knowledge and which we refer to ourselves. Such psychological experience, moreover, in itself or in its content, must be fully available to us here and now for the needs of the present moment. (1954, p. 209. Original emphases.)

Accordingly, unconscious in its simplest sense means the absence of the activities of knowing, wanting, doing, remembering, and reflecting. A disturbance of consciousness is an interference with these activities, or their temporary loss.

Of course, some of these activities may not be observable. A person may not be able to move or to talk, yet he may be fully aware of what goes on around him. But to be conscious at all, he must be able to perceive and evaluate what he perceives. To be fully conscious, he must be aware of the external world and of his own experience, present and past, and must be able to use what he knows.

Consciousness, like memory, has been a step-child of psychological science during the last few decades. But unlike memory, it has not as yet made a comeback. Early in this century, when psychology had barely been accepted as an experimental science, Watson had insisted that consciousness is not a fit object for scientific research; that science has to restrict itself to the investigation of phenomena accessible to public observation and measurement. Whatever the methodological reasons for such an ostrich policy, psychologists have followed it for many a long year. This neglect of consciousness has impoverished experimental psychology and has deprived clinical psychology and psychiatry of help in an area crucial for understanding mental disorders as well as the effects of brain injury. Only recently, with the advent of cognitive psychology, have theorists come to realize that there is an important gap in their scientific domain. As Norman (1979) says: “the phenomenon of consciousness is so fundamental to our mental lives that it seems strange that experimental psychologists have ignored it so conclusively.” (p. 142.)

While the functioning of at least some afferent sensory pathways is necessary for consciousness, the normal functioning of the sensory system is not sufficient. Experimental subjects may not even “see” a word presented tachistoscopically when it is “masked” by an inappropriate word that follows immediately afterward. According to Allport (1979), conscious awareness depends on a preattentive processing of visual impressions. An unconscious patient may receive sensory impressions (as shown by electrical potentials recorded from the sensory cortex) yet be unable to react to them in any way. In contrast, a person may move and even speak, yet be unable to reflect on what he is doing or remember his actions afterwards—for instance, in “temporal automatisms” (Penfield, 1952).

Full consciousness necessarily includes a person's ability to remember what is happening or what he is doing, and also to remember who he is, where he is, and what he is about to do. So-called “clouding of consciousness” is characterized by confusion: The patient does not know where he is, what year or season it is, or who are the people around him. Although this state has been defined differently by different psychiatrists, there is agreement on the main symptoms. The patient is confused, incoherent, inattentive, misidentifies things and people; in short, is unable to grasp the real situation. As a result, the patient is disinclined to move, is in...