Source : Memory and the brain
Color coding : Violet - Question Red - Claim Blue - Evidence Green - Assumption Yellow - Constraints
Reinforcement, Reward: Appraisal and Affective Memory
In the last chapter, I have argued that attention is a necessary condition for perceiving and remembering, and that attention is initiated by an appraisal that this is good to know. Perception, aided by memory, eventually leads to action. But before we can approach anything or even want to do so, we must appraise it as good for us in some way: good to know, which leads to attention; good to have, which results in wanting and approaching it. We must also appraise a possible action as "good to do" and want to do it. No memory experiment will succeed unless the subject wants to learn, remember what he has learned, and wants to report it. Although modern cognitive psychologists are apt to disregard motivation in connection with memory experiments, the subjects must be motivated to do what the experimenter asks them to do. Given the docility of the usual subjects, psychology students, all the motivation they need is to know that participating in the experiment is required for a passing grade.
In animals, a psysiological state or drive (hunger, thirst) is assumed to impel the animal toward something (food, water) that will satisfy the drive. But both human beings and animals must be motivated to learn what the experimenter expects them to learn. Learning has usually been ascribed to the "law of effect" ( Thorndike, 1931), or the reinforcement of the correct response. In other words, the subject must be reinforced by each correct response to go on learning. Thorndike assumed that the correct response strengthens the stimulus-response association directly and automatically. He rejected the view that reinforcement merely determines the choice of response after correct recall. Later views of reinforcement have been divided between these two views ( Atkinson & Wickens, 1971). One view sees reinforcement as influencing the registration of memory (learning), the other, as determining the retrieval (performance). Some theorists are beginning to doubt that reinforcement theory, developed from animal research, can apply to human learning ( Estes, 1971). In answer, Voss ( 1971) points out that the real priority is to develop a satisfactory theory of human learning, and a theory of animal learning will take care of itself. He says: "Thus, even if one adheres to the continuity position, it does not necessarily follow that a reinforcement framework should be adopted for understanding reward and punishment in human learning; instead, it also would be possible that development of some other view may be fruitful, and even applicable to animal behavior" (p. 39).
Despite the vast research effort devoted to this problem for many years, none of the available reinforcement theories spells out just how reward or reinforcement produces its effect. True, the learner is rewarded and the response (or the association between learned items) is reinforced. But how does the reward promote learning, or how is the response reinforced? I propose to review briefly the more important motivational theories to discover whether any of the mechanisms proposed explains the function of reinforcement and could aid in the quest of identifying the pathways that mediate its effects.
REINFORCEMENT THEORIES
In an extensive review, Tapp ( 1969) classifies reinforcement theories, according to the main factor stressed, as motivational theories, stimulus theories and response theories. I follow him in this ordering.
Among motivational theories, Tapp points out, the drive-reduction theory has found considerable experimental support. According to this theory, the drive spurs the animal to learn a task; successful performance reduces the drive. But the theory cannot explain why "animals will learn a task . . . to taste a nonnutritive sweet substance . . . press bars to turn on lights or receive a puff of a novel odor . . . run mazes . . . to explore an empty goal box. . . . (or why) they will work to receive electric shocks or injections of minute amounts of chemicals into certain parts of their brain." (p. 390). None of these performances can reduce a physiological drive. The only way these experimental findings could be incorporated into the drive-reduction theory would be to postulate a new drive for every new reward, which, as Tapp says, would be rather uncomfortable.
The newer arousal theories ( Berlyne, 1967) hold that a stimulus or a need that moves the animal from an optimal state of arousal induces drive or tension; and anything that reduces this state again to an optimal level is reinforcing. Such theories avoid the paradox fatal to drive reduction theories that organisms sometimes seek arousal, and not drive reduction. But the concept of arousal, taken from the reported EEG arousal on stimulation of the brainstem reticular system, has little definition and suffers from lack of agreement as to what constitutes arousal. In addition, Berlyne's argument states that a reward is reinforcing when it can induce an optimal level of arousal. And the arousal potential of the reward is a function of the arousal level of the subject (his need). But how does the optimal (or near optimal) level of arousal reinforce?
Thursday, June 24, 2010
Tuesday, June 22, 2010
The connection between consciousness, perception and memory
The role of basic senses
Our senses first connect us with the external world. External-world consists of physical matters in different forms. We have the tools through which we come to know what is around us. Our sense mechanisms help us to be aware their existence.
Our basic senses include ability to see objects, ability to hear sound, capacity to feel through our skin and body surface, ability to smell and taste. They are mediated by the sense organs which takes the signal to our brain.
Do we have other senses ?
The basic senses helps us with the basic signals which they generate through our organs but the brain processes these signals in various ways to make us sensitive to other aspect of the physical world and also about our own self to control ourselves in various ways.
If we close our eyes and take our hand towards our nose, we can do it accurately. So we can sense our body parts and their locations and movements through the space.
Perception
Imagine that you are walking on the road and there is traffic on the road. How do you know, you are walking on the road? You feel the hard surface of the road. You see the stretch of road in front of you. You can hear the sound of the traffic and you can see the surrounding environment. Hence you become aware that you are walking on the road. You perceive yourself to be walking on the road.
As you can see from the above that different senses must integrate to develop the perception. Although you may not be attending to any specific matter separately but still you become aware that you are walking on the road. So perception is a preattentive phenomenon. And it is a direct in nature because you directly know of the object, environment or a concept.
Why memory is important for perception
When you wave your finger in front of someone, he immediately becomes aware what is happening before him. He is recognizes that what is that being moved in front of his face. It is your finger. How did he come to know of it? He must have seen the structure of the finger and remembers it. He unconsciously breaks the impression generated from is visual field into perceptible divisions and then come to know that moving structure is a finger and it is the finger of the man in front of him.
How do we know that something is moving in front of us? We see a structure of an object and also become aware that on a time difference the objects position changes in the space. This means we must remember the previous positions of the object to compare the various changed positions of the object that is moving. This proves that the perception of motion is a result of interaction happening between the various parts of the brain that processes our sensory stimuli and also uses the impressions that we are continuously storing in our memory over a period of time.
Spatial Perception
When we move around we can clearly understand where the objects are placed. Our eyes and ears help us to locate and understand the specific location of an object. We can understand relative distance between several objects and also from our own body. We also become aware of how the objects are distributed in the space before us.
A blind person can understand shape by remembering his own hand movements. This kind of memory may be termed as motor memory. So every time you ask a blind man to trace a circle he will be able to tell you that what shape he has traced. But if he suddenly gets back hi vision and sees a circle. He will never be able to tell that the shape is a circle. this is because what he remembers is what he traced moving his hand. He has no memory of a circles visual shape. But if he traces it out on the surface, he will be able to connect the visual experience with his motor memory of hand movements that he used during the tracing action.
It is seen that blind persons who are lacking their vision from their birth can move around in their familiar places. And they do it quite effectively. This means they remember the concept of arrangement of objects in the spece around them. They carry a mental map of how each of the objects are placed in the space within which they operate.
Normally a person with vision will have the map defined in some way in the brain and a blind person will have it in a different way in their brain. But one thing is true that in both of the cases t the entire spatial concept is stored in the memory in some way or other.
Consciousness
To be conscious simply means to be aware of the surrounding environment and actuvities. A conscious person can feel, think, move, understand and cmmunicate. He can remember things of past, plan for future and relflect on what he remembers.
Being unconscious similarly means the opposite. An unconsious person cannot think, understand, move, communicate, remember and reflect.
But to be conscious a person has to be capable of percieve things and also should be able evaluate the precieved idea or concept. The prcess of evaluation will be possible only if he can remember the past experiences, compare them with new experiences. This means to be conscious a person must have memory.
On the other hand if a person gets the sensory inputs in his bain but cannot repond to it he is no more conscious. If the memory recall process is affected and a person cannot remember the past data, we call it clouding of consiousness. A person is confused because he cannot remember where he is, what time it is, with whom he is speaking, or even who he is. This is also known as disorientation. Such a person's thinking become incoherent and
Today, the connection between perception and memory is increasingly recognized ( Murdock, 1979; Turvey & Shaw, 1979). When we try to identify the processes used in perception, we find that we must be aware of a situation, attend to it, and identify it by recalling similar situations. Often, when memory fails, we imagine what must have happened to fill the gaps. We can recall and imagine something seen or heard, even smelled, tasted or touched..
References
Memory and brain, Chapter : Perception
Our senses first connect us with the external world. External-world consists of physical matters in different forms. We have the tools through which we come to know what is around us. Our sense mechanisms help us to be aware their existence.
Our basic senses include ability to see objects, ability to hear sound, capacity to feel through our skin and body surface, ability to smell and taste. They are mediated by the sense organs which takes the signal to our brain.
Do we have other senses ?
The basic senses helps us with the basic signals which they generate through our organs but the brain processes these signals in various ways to make us sensitive to other aspect of the physical world and also about our own self to control ourselves in various ways.
If we close our eyes and take our hand towards our nose, we can do it accurately. So we can sense our body parts and their locations and movements through the space.
Perception
Imagine that you are walking on the road and there is traffic on the road. How do you know, you are walking on the road? You feel the hard surface of the road. You see the stretch of road in front of you. You can hear the sound of the traffic and you can see the surrounding environment. Hence you become aware that you are walking on the road. You perceive yourself to be walking on the road.
As you can see from the above that different senses must integrate to develop the perception. Although you may not be attending to any specific matter separately but still you become aware that you are walking on the road. So perception is a preattentive phenomenon. And it is a direct in nature because you directly know of the object, environment or a concept.
Why memory is important for perception
When you wave your finger in front of someone, he immediately becomes aware what is happening before him. He is recognizes that what is that being moved in front of his face. It is your finger. How did he come to know of it? He must have seen the structure of the finger and remembers it. He unconsciously breaks the impression generated from is visual field into perceptible divisions and then come to know that moving structure is a finger and it is the finger of the man in front of him.
How do we know that something is moving in front of us? We see a structure of an object and also become aware that on a time difference the objects position changes in the space. This means we must remember the previous positions of the object to compare the various changed positions of the object that is moving. This proves that the perception of motion is a result of interaction happening between the various parts of the brain that processes our sensory stimuli and also uses the impressions that we are continuously storing in our memory over a period of time.
Spatial Perception
When we move around we can clearly understand where the objects are placed. Our eyes and ears help us to locate and understand the specific location of an object. We can understand relative distance between several objects and also from our own body. We also become aware of how the objects are distributed in the space before us.
A blind person can understand shape by remembering his own hand movements. This kind of memory may be termed as motor memory. So every time you ask a blind man to trace a circle he will be able to tell you that what shape he has traced. But if he suddenly gets back hi vision and sees a circle. He will never be able to tell that the shape is a circle. this is because what he remembers is what he traced moving his hand. He has no memory of a circles visual shape. But if he traces it out on the surface, he will be able to connect the visual experience with his motor memory of hand movements that he used during the tracing action.
It is seen that blind persons who are lacking their vision from their birth can move around in their familiar places. And they do it quite effectively. This means they remember the concept of arrangement of objects in the spece around them. They carry a mental map of how each of the objects are placed in the space within which they operate.
Normally a person with vision will have the map defined in some way in the brain and a blind person will have it in a different way in their brain. But one thing is true that in both of the cases t the entire spatial concept is stored in the memory in some way or other.
Consciousness
To be conscious simply means to be aware of the surrounding environment and actuvities. A conscious person can feel, think, move, understand and cmmunicate. He can remember things of past, plan for future and relflect on what he remembers.
Being unconscious similarly means the opposite. An unconsious person cannot think, understand, move, communicate, remember and reflect.
But to be conscious a person has to be capable of percieve things and also should be able evaluate the precieved idea or concept. The prcess of evaluation will be possible only if he can remember the past experiences, compare them with new experiences. This means to be conscious a person must have memory.
On the other hand if a person gets the sensory inputs in his bain but cannot repond to it he is no more conscious. If the memory recall process is affected and a person cannot remember the past data, we call it clouding of consiousness. A person is confused because he cannot remember where he is, what time it is, with whom he is speaking, or even who he is. This is also known as disorientation. Such a person's thinking become incoherent and
Today, the connection between perception and memory is increasingly recognized ( Murdock, 1979; Turvey & Shaw, 1979). When we try to identify the processes used in perception, we find that we must be aware of a situation, attend to it, and identify it by recalling similar situations. Often, when memory fails, we imagine what must have happened to fill the gaps. We can recall and imagine something seen or heard, even smelled, tasted or touched..
References
Memory and brain, Chapter : Perception
Sunday, June 20, 2010
Study Notes - Memory and the brain - Chapter : Attention
Source : Memory and the brain
Color coding : Violet - Question Red - Claim Blue r- Evidence Green - Assumption Yellow - Constraints
To become aware of sensory experience apparently requires more than the activity of the different sense modalities. It requires a turning toward the source of such experience: it requires attention.
According to William James, everyone knows what attention is: "It is the taking possession by the mind, in clear and vivid form, of one out of . . . several simultaneously possible objects or trains of thought." ( 1890, p. 403.) But how do we pay attention, what is this "taking possession by the mind"? Is it a cognitive process? Most psychologists would unhesitatingly answer that it is. However, our experience speaks against this interpretation.
Take, for example, seeing, hearing, or touching: these are cognitive processes. They mediate knowledge and do so directly, immediately. We see as soon as we open our eyes, provided there is enough light; we hear whenever there is a sound, provided we are awake and our attention is not otherwise engaged. In contrast, attention is directed here or there, and can be withdrawn from something in front of our eyes and directed toward something imagined or remembered. Attention can increase the intensity of a sense experience: if we expect a sound, attention can lower the threshold of hearing. When directed elsewhere, attention may altogether prevent perception. Attention is a condition of cognition just as light is a condition of sight. A man engrossed in a book may not be aware that somebody is asking him a question. That he hears is shown by the fact that calling his name will attract his attention, although the questioner may not have raised his voice. Cognitive functions do not act in this manner. Sight, hearing, touch, smell, taste, simply mediate experience, they do not change it. They neither increase nor decrease the intensity of experience. Sensory receptors receive changes in cortical sensory areas even during sleep or light anesthesia.
Attention makes reflective knowledge or awareness possible; but is attention itself a cognitive function? This problem is usually not talked about. Recent experiments and theories of attention ( Norman, 1968, 1969; Kahneman, 1973) treat the effect of attention on sensory experience at great length, but never raise the question whether attention itself is cognitive in nature. As a result, theorists often conceive of the sensory system as a single communication channel with a selective filter (attention) that is part of the system and filters out irrelevant sensory impressions ( Broadbent, 1958; Bower, 1967). This filter, they postulate, can be tuned to any one of several inputs. Only information passed by the filter can be further processed and remembered.
Such a model seems to fit experiments on selective listening in which the subject is asked to repeat aloud what he hears in one ear while a different (irrelevant) message is fed to the other ear. In these experiments, the subject can switch attention at will from one message to the other, even when the voices in the two channels are identical. In fact, Spieth et al. ( 1954) found that such selective listening was possible when the voices were heard over loudspeakers placed only ten to twenty degrees apart. The subjects could also follow a voice coming through a low-pass filter, rather than one sent through a high-pass filter. Finally, Egan et al. ( 1954) found that the subjects can attend either to intensity or to frequency of sounds. In short, it is possible to attend to one of two simultaneous sequences of sounds different in quality, location, intensity, and frequency.
However, when the irrelevant (unattended) message contains the subject's name, he begins to attend to it ( Moray, 1959); also, he switches from one ear to the other when the message in that ear becomes relevant, for instance, when the message in the non-attending ear continues the passage read to the attending ear ( Treisman, 1960, 1964a,b). This switching in the middle of the message is difficult to explain on the basis of a filter theory. How can relevant stimuli on unattended channels capture attention? This problem is discussed by Craik and Jacoby ( 1979). For instance, several subjects recognized the rejected message if it was identical with the message they attended to. In fact, some bilingual subjects recognized such identity although the unattended message was in another language ( Treisman, 1964a,b). Treisman tried to explain this phenomenon by postulating several levels of processing, and insisted that the level reached depends not only on the physical characteristic of the stimulus but on current expectations in the analyzing system. Broadbent ( 1971) later accepted this modification of his filter theory. But neither the original theory nor Treisman's modification can explain how attention can be directed toward meaningful material when the filter is only equipped to deal with the physical features of the stimulus. It can hardly have biases and expectations that go beyond these characteristics. Norman ( 1968, 1969) has faced the difficulty of explaining a switch of attention on the basis of a filter model. He claims that a model that can account for such changed filters needs a more complicated system. According to him,
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Notes : Attention according ..... filter theory is equiped to deal with physicalfeatures of the stimulus but it does not explain how attention can be directed toward meaningful material.
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"all signals arriving at sensory receptors pass through a stage of analysis performed by the early physiological processes. Then, the parameters extracted from the processes are used to determine where the representation of the sensory signal is stored. Thus . . . all sensory signals excite their stored representation in memory. Now, at the same time, we assume that an analysis of previous signals is going on. This establishes a class of events deemed to be pertinent to the ongoing analysis. The set of pertinent items also excite their representation in memory. The item most highly excited by the combination of sensory and pertinent inputs is selected for further analysis." ( Norman, 1969, p. 33)
The difficulty with this description is that we are not certain what Norman is speaking about. Is he referring to a neural network, a computer model, a flow diagram, or a set of human activities? Often, Norman speaks explicitly of human mental processes, particularly in his later articles ( Norman, 1979). But he also describes processes that operate on knowledge structures in an almost mechanical way. When he speaks of "the item most highly excited by the combination of sensory and pertinent inputs," which is selected for further analysis (and presumably attended to), we begin to wonder whether he is perhaps alluding to the neural network. In such a network, the most intense excitation wins out. But the human being may pay attention not to the lecturer's loud voice and erudite discourse but to a fleeting distraction -- and who is to decide whether the distracting thought is more intense? Norman's notion of attention as the algebraic sum of excitation from perception and memory analyses does not explain why a subject should recognize a message read to the non-attending ear as identical with the message to which he has been paying attention all along, particularly when the two messages are in different languages. Nor does it explain why a memory analysis should establish a pertinent item in the first place -- unless it is the human being who decides what is relevant and directs his recall accordingly.
Both Norman's and Broadbent's models depend on the presence of memory traces, some of which are excited by the sensory input. But can we assume that there will always be stored memories to select an item for attention? Supposing a subject is instructed to press a button every time he sees a shade of red in the tachistoscope. No matter how many shades are shown, the subject has no difficulty in judging them correctly as red and pressing the button. The notion that there must be a memory trace for every type and intensity of sensory experience leads, as Norman says in another connection, "to a staggering amount of complexity in the neural network required to do the task. Moreover, it is not clear that any finite network could ever suffice, for there are truly an infinite number of ways we can see well-known objects" ( 1969, p. 40). Norman's solution is to suggest that stimulus-analyzing mechanisms recognize patterns, and recognize them by rules: "a set of rather general purpose operations examine the set of features extracted by the basic physiological analyzers and classify patterns, more by synthesizing them anew than by any other procedure" (p. 40). But if attention is merely the effect of various operations, as Norman says, the model does not explain how the subject decides that a given color is a shade of red. If he is instructed to look for "red," so that the instructions make this color pertinent, how does the expectation so aroused excite the trace for that particular shade? The concept "red" has no particular shade, hence there can be no memory trace for any given shade. Even if we assume, as some theorists do, that a concept is the generalized image of a class of objects, that is, a generalized shade of red, how can a particular shade excite the trace of such a generalized memory image? Again, it is the human being and not a stimulus-analyzing mechanism that forms concepts and recognizes a given shade of red as belonging to the class of "red."
Neisser ( 1967), a cognitive psychologist, also insists that attention "is simply an allotment of analyzing mechanisms to a limited region of the field. To pay attention to a figure is to make certain analyses of, or certain constructions in, the corresponding part of the icon." (p. 89.) For Neisser, focal attention can function only after "preattentive" global processes have already segregated the figural units involved. He insists that even a mechanical recognition system would have to have such a feature for separating certain units and selecting one after another for further processing.
Neisser's "preattentive processes" have an obvious similarity with the integrative sense discussed in chapter 1; so do Norman's stimulus-analyzing mechanisms. Without the ability to see a well-articulated scene, or to distinguish patterns of sound, it would be impossible to direct attention to any part of the visual field, or to begin listening to discover the drift of a conversation or the theme of a musical composition.
Like Norman, Neisser seems to consider attention simply as the result of certain preconscious operations. When he says that attention is "the allotment of analyzing mechanisms," who or what makes the allotment? Neisser disagrees with psychoanalytic writers who regard attention as the manifestation of a single process, an allocation of energy; but his own formulation shows little improvement. Whether attention is a process of allocating energy, or the allotment of analyzing mechanisms, we have no clue how this allotment is done, just as we do not know how the allocation of energy can result in attention.
It is more than doubtful that the same preattentive or preconscious process that segregates the manifold of sensory impressions into distinguishable units could also select a given unit for further processing. The preattentive global process that results in crude percepts cannot direct what is to be done next. Another function is needed that will allot mechanisms, allocate energy, and direct the memory search. And when we ask with Neisser: Who does the searching, the allotting? Is there a little man in the head, a homunculus? Neisser answers: As recently as a generation ago, processes of control had to be thought of as homunculi, because man was the only known model of the executive agent. Today, the stored-program computer has provided us with an alternative possibility, in the form of the executive routine. This is a concept which may be of considerable use to psychology. ( 1967, p. 295.)
Of course, Neisser admits that the executive routines must be programmed into the computer from the beginning and would not allow a change of direction in midstream, yet this is a common phenomenon in human experience. In man, he thinks, such executive functions are acquired through experience -- a case of learning like any other.
But learning is not the explanation. We do not learn attention, we merely learn to what we should attend, just as we do not learn to see, we merely learn to interpret what we see. It is odd that psychologists should be willing to accept "executive routines" that somehow (nobody knows how) direct man's behavior, when they are unwilling to agree that the human being directs his own behavior, yet that is a fact of everybody's direct experience. The very notion of a "little man in the head" could gain credence only because psychologists were convinced that psychological activities, like the movements of physical bodies, must be explained objectively, without appealing to any human agency. Yet a human being sees, pays attention to what he sees, appraises it, thinks about it, chooses to react to it in some way. He sometimes throws a ball or digs a ditch. We do not assume that a little man in the head pulls strings to make us see, make us dig ditches or throw a ball -- why should we need a homunculus to attend to something, to remember, to think?
To insist that human behavior is the result of learned executive routines is to indulge in a double analogy, from man to machine and from machine to man. Executive routines are instructions directing computer searches, on the analogy of a human being directing himself or others to investigate a particular area of interest. Instead of assuming that the human being uses executive routines, it is much simpler and closer to human experience to assume that we use various functions to deal with the world around us. When we do that, the only problem left is to identify the functions needed in a particular activity.
There has never been any difficulty about obvious sensory functions. Seeing, hearing, smelling, touching, and tasting have always been accepted as something we do -- except for early behaviorists who admitted responses to stimuli, but not the perception of stimuli. But the notion of an integrative sense that enables us to see objects rather than colored patches has found few adherents until it surfaced comparatively recently in the guise of global preattentive processes ( Neisser, 1967). Yet it is obvious that the visual sense itself can only mediate color. However, special cell columns in the visual cortex have been found to respond to vertical, horizontal, and oblique lines, and to movement ( Hubel & Wiesel, 1962). Hence it is the visual cortex with its six layers that seems to mediate vis- ual form and movement. It is a reasonable inference that the feltwork of the sensory cortex mediates sensory integration and articulates the visual field in such a way that we can focus on any part of it.
The primary function of attention is not that of analyzing or integrating sensory impressions, but of focusing other functions on the area of interest. We turn toward the object of attention, look, listen, and try to discover what we can about it. In other words, attention is a desire to see, hear, taste, smell, touch, think about, and so to know something as best we may. Attention requires some kind of intuitive or deliberate, unconscious or conscious judgment that something is worth knowing or investigating. Attention can be voluntary or involuntary. Involuntary attention is based on an intuitive, unwitting appraisal: a sudden loud sound, a bright color in a dull landscape, a whiff of perfume, or an unpleasant smell, all of these can alert us and draw our attention. Voluntary attention, on the other hand, is based on a person's conscious, deliberate judgment that this particular thing is something worth knowing about. If an experimental subject is instructed to press a button every time he sees a shade of red, he attends to the visual array. He wants to know it so that he can respond to it. As long as this desire lasts, he will be "set" to notice and report the shade that fits the concept. He may see other colors but will not react to them and may not even remember them.
Posner ( 1973) allows for both preconscious and conscious perceptual processing in his model of attention. A single-channel central processing capacity represents conscious attention, and is followed by rehearsal and the choice of response. Conscious attention is made possible by two stages of perceptual processing: the encoding of the stimulus, and a comparison of the stimulus with the contents of long-term memory. In his experiments, Posner showed a target stimulus (a digit or letter) to the subject, and later an array of similar stimuli with the instruction to locate the target stimulus. According to Posner, this search and comparison is preconscious. He comments that "both the target and non-target items are subject to a memory search process but only the target item gives rise to the phenomenological experience of jumping out at the subject." (p. 41.) But there is considerable doubt that this experience of the stimulus jumping out at the subject is the result of a comparison of each array stimulus with the remembered target stimulus. Indeed, research findings seem to be against such an assumption. For instance, Sternberg ( 1975) had his subjects commit a set of stimuli (letters, digits, figures) to memory; he called this the "positive set." He then showed a single test stimulus and asked his subjects to press one switch if the test stimulus was a member of the positive set, another if it was not. Sternberg found that the reaction time was so short that the subjects must have made about thirty comparisons per second, a rate considerably faster than the rate of subvocal speech which might have to be used for such comparisons. Sternberg also reported that the subjects were not aware of any search or comparison. Apparently the test stimulus simply felt familiar.
This is a prime example of an assumption based on a computer analogy: because the computer can locate the test stimulus only by search and comparison, the human being must do so, too. But the human being can recognize the test stimulus if he has seen it before (or memorized it, in Sternberg's experiment), that is, he can find it familiar. Recognition has always been considered different from recall. It is inaccessible to analysis, accounts for the target stimulus "jumping out" at the subject and is far faster than recall and comparison could ever be. In chapter 5, I discuss the difference between recall and recognition at greater length. Here, I will merely point out that recognition attracts attention (the stimulus "jumps out").
Shevrin and Dickman ( 1980) reviewed several different theories of attention and perception, all of which assume preconscious processing. A few of them also assume that such processing is qualitatively different from conscious attention. These authors suggested, on the basis of the available body of experimental research, that an initial preconscious stage of cognition is psychological (not physiological), affects conscious experience and may differ from conscious cognition in its principles of operation; conscious cognition is a later stage.
I would like to suggest that this preconscious cognition is an intuitive appraisal of something as familiar, or as good to know better because unfamiliar; this arouses a desire to turn toward it, look, listen, and investigate it. In the case of familiar objects, their recognition brings about a desire to do something about it, whether to report the occurrence or respond to it as usual. Hence attention is an appetitive and not a cognitive function. We want to turn toward the object, look, and listen. This immediately solves the problem of selective attention: all appetition implies a choice of goal, whether we want a new hat, a meal, to travel to Europe, or to look at a new car. If we attend to something, we select out of many possible things one we want to know better, whether we want to listen to a recording, watch an eclipse, or report on shades of red, locate a target stimulus, or identify the test stimulus in the positive set.
Involuntary attention, then, is the same impulse to look and listen, but based on the completely unconscious intuitive appraisal that this is unfamiliar, and should be investigated. Voluntary attention is based on a deliberate, conscious appraisal. In both cases, we have an impulse to focus on the selected object. But in voluntary attention, we want to look, in involuntary attention, we feel an urge to look.
Color coding : Violet - Question Red - Claim Blue r- Evidence Green - Assumption Yellow - Constraints
To become aware of sensory experience apparently requires more than the activity of the different sense modalities. It requires a turning toward the source of such experience: it requires attention.
According to William James, everyone knows what attention is: "It is the taking possession by the mind, in clear and vivid form, of one out of . . . several simultaneously possible objects or trains of thought." ( 1890, p. 403.) But how do we pay attention, what is this "taking possession by the mind"? Is it a cognitive process? Most psychologists would unhesitatingly answer that it is. However, our experience speaks against this interpretation.
Take, for example, seeing, hearing, or touching: these are cognitive processes. They mediate knowledge and do so directly, immediately. We see as soon as we open our eyes, provided there is enough light; we hear whenever there is a sound, provided we are awake and our attention is not otherwise engaged. In contrast, attention is directed here or there, and can be withdrawn from something in front of our eyes and directed toward something imagined or remembered. Attention can increase the intensity of a sense experience: if we expect a sound, attention can lower the threshold of hearing. When directed elsewhere, attention may altogether prevent perception. Attention is a condition of cognition just as light is a condition of sight. A man engrossed in a book may not be aware that somebody is asking him a question. That he hears is shown by the fact that calling his name will attract his attention, although the questioner may not have raised his voice. Cognitive functions do not act in this manner. Sight, hearing, touch, smell, taste, simply mediate experience, they do not change it. They neither increase nor decrease the intensity of experience. Sensory receptors receive changes in cortical sensory areas even during sleep or light anesthesia.
Attention makes reflective knowledge or awareness possible; but is attention itself a cognitive function? This problem is usually not talked about. Recent experiments and theories of attention ( Norman, 1968, 1969; Kahneman, 1973) treat the effect of attention on sensory experience at great length, but never raise the question whether attention itself is cognitive in nature. As a result, theorists often conceive of the sensory system as a single communication channel with a selective filter (attention) that is part of the system and filters out irrelevant sensory impressions ( Broadbent, 1958; Bower, 1967). This filter, they postulate, can be tuned to any one of several inputs. Only information passed by the filter can be further processed and remembered.
Such a model seems to fit experiments on selective listening in which the subject is asked to repeat aloud what he hears in one ear while a different (irrelevant) message is fed to the other ear. In these experiments, the subject can switch attention at will from one message to the other, even when the voices in the two channels are identical. In fact, Spieth et al. ( 1954) found that such selective listening was possible when the voices were heard over loudspeakers placed only ten to twenty degrees apart. The subjects could also follow a voice coming through a low-pass filter, rather than one sent through a high-pass filter. Finally, Egan et al. ( 1954) found that the subjects can attend either to intensity or to frequency of sounds. In short, it is possible to attend to one of two simultaneous sequences of sounds different in quality, location, intensity, and frequency.
However, when the irrelevant (unattended) message contains the subject's name, he begins to attend to it ( Moray, 1959); also, he switches from one ear to the other when the message in that ear becomes relevant, for instance, when the message in the non-attending ear continues the passage read to the attending ear ( Treisman, 1960, 1964a,b). This switching in the middle of the message is difficult to explain on the basis of a filter theory. How can relevant stimuli on unattended channels capture attention? This problem is discussed by Craik and Jacoby ( 1979). For instance, several subjects recognized the rejected message if it was identical with the message they attended to. In fact, some bilingual subjects recognized such identity although the unattended message was in another language ( Treisman, 1964a,b). Treisman tried to explain this phenomenon by postulating several levels of processing, and insisted that the level reached depends not only on the physical characteristic of the stimulus but on current expectations in the analyzing system. Broadbent ( 1971) later accepted this modification of his filter theory. But neither the original theory nor Treisman's modification can explain how attention can be directed toward meaningful material when the filter is only equipped to deal with the physical features of the stimulus. It can hardly have biases and expectations that go beyond these characteristics. Norman ( 1968, 1969) has faced the difficulty of explaining a switch of attention on the basis of a filter model. He claims that a model that can account for such changed filters needs a more complicated system. According to him,
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Notes : Attention according ..... filter theory is equiped to deal with physicalfeatures of the stimulus but it does not explain how attention can be directed toward meaningful material.
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"all signals arriving at sensory receptors pass through a stage of analysis performed by the early physiological processes. Then, the parameters extracted from the processes are used to determine where the representation of the sensory signal is stored. Thus . . . all sensory signals excite their stored representation in memory. Now, at the same time, we assume that an analysis of previous signals is going on. This establishes a class of events deemed to be pertinent to the ongoing analysis. The set of pertinent items also excite their representation in memory. The item most highly excited by the combination of sensory and pertinent inputs is selected for further analysis." ( Norman, 1969, p. 33)
The difficulty with this description is that we are not certain what Norman is speaking about. Is he referring to a neural network, a computer model, a flow diagram, or a set of human activities? Often, Norman speaks explicitly of human mental processes, particularly in his later articles ( Norman, 1979). But he also describes processes that operate on knowledge structures in an almost mechanical way. When he speaks of "the item most highly excited by the combination of sensory and pertinent inputs," which is selected for further analysis (and presumably attended to), we begin to wonder whether he is perhaps alluding to the neural network. In such a network, the most intense excitation wins out. But the human being may pay attention not to the lecturer's loud voice and erudite discourse but to a fleeting distraction -- and who is to decide whether the distracting thought is more intense? Norman's notion of attention as the algebraic sum of excitation from perception and memory analyses does not explain why a subject should recognize a message read to the non-attending ear as identical with the message to which he has been paying attention all along, particularly when the two messages are in different languages. Nor does it explain why a memory analysis should establish a pertinent item in the first place -- unless it is the human being who decides what is relevant and directs his recall accordingly.
Both Norman's and Broadbent's models depend on the presence of memory traces, some of which are excited by the sensory input. But can we assume that there will always be stored memories to select an item for attention? Supposing a subject is instructed to press a button every time he sees a shade of red in the tachistoscope. No matter how many shades are shown, the subject has no difficulty in judging them correctly as red and pressing the button. The notion that there must be a memory trace for every type and intensity of sensory experience leads, as Norman says in another connection, "to a staggering amount of complexity in the neural network required to do the task. Moreover, it is not clear that any finite network could ever suffice, for there are truly an infinite number of ways we can see well-known objects" ( 1969, p. 40). Norman's solution is to suggest that stimulus-analyzing mechanisms recognize patterns, and recognize them by rules: "a set of rather general purpose operations examine the set of features extracted by the basic physiological analyzers and classify patterns, more by synthesizing them anew than by any other procedure" (p. 40). But if attention is merely the effect of various operations, as Norman says, the model does not explain how the subject decides that a given color is a shade of red. If he is instructed to look for "red," so that the instructions make this color pertinent, how does the expectation so aroused excite the trace for that particular shade? The concept "red" has no particular shade, hence there can be no memory trace for any given shade. Even if we assume, as some theorists do, that a concept is the generalized image of a class of objects, that is, a generalized shade of red, how can a particular shade excite the trace of such a generalized memory image? Again, it is the human being and not a stimulus-analyzing mechanism that forms concepts and recognizes a given shade of red as belonging to the class of "red."
Neisser ( 1967), a cognitive psychologist, also insists that attention "is simply an allotment of analyzing mechanisms to a limited region of the field. To pay attention to a figure is to make certain analyses of, or certain constructions in, the corresponding part of the icon." (p. 89.) For Neisser, focal attention can function only after "preattentive" global processes have already segregated the figural units involved. He insists that even a mechanical recognition system would have to have such a feature for separating certain units and selecting one after another for further processing.
Neisser's "preattentive processes" have an obvious similarity with the integrative sense discussed in chapter 1; so do Norman's stimulus-analyzing mechanisms. Without the ability to see a well-articulated scene, or to distinguish patterns of sound, it would be impossible to direct attention to any part of the visual field, or to begin listening to discover the drift of a conversation or the theme of a musical composition.
Like Norman, Neisser seems to consider attention simply as the result of certain preconscious operations. When he says that attention is "the allotment of analyzing mechanisms," who or what makes the allotment? Neisser disagrees with psychoanalytic writers who regard attention as the manifestation of a single process, an allocation of energy; but his own formulation shows little improvement. Whether attention is a process of allocating energy, or the allotment of analyzing mechanisms, we have no clue how this allotment is done, just as we do not know how the allocation of energy can result in attention.
It is more than doubtful that the same preattentive or preconscious process that segregates the manifold of sensory impressions into distinguishable units could also select a given unit for further processing. The preattentive global process that results in crude percepts cannot direct what is to be done next. Another function is needed that will allot mechanisms, allocate energy, and direct the memory search. And when we ask with Neisser: Who does the searching, the allotting? Is there a little man in the head, a homunculus? Neisser answers: As recently as a generation ago, processes of control had to be thought of as homunculi, because man was the only known model of the executive agent. Today, the stored-program computer has provided us with an alternative possibility, in the form of the executive routine. This is a concept which may be of considerable use to psychology. ( 1967, p. 295.)
Of course, Neisser admits that the executive routines must be programmed into the computer from the beginning and would not allow a change of direction in midstream, yet this is a common phenomenon in human experience. In man, he thinks, such executive functions are acquired through experience -- a case of learning like any other.
But learning is not the explanation. We do not learn attention, we merely learn to what we should attend, just as we do not learn to see, we merely learn to interpret what we see. It is odd that psychologists should be willing to accept "executive routines" that somehow (nobody knows how) direct man's behavior, when they are unwilling to agree that the human being directs his own behavior, yet that is a fact of everybody's direct experience. The very notion of a "little man in the head" could gain credence only because psychologists were convinced that psychological activities, like the movements of physical bodies, must be explained objectively, without appealing to any human agency. Yet a human being sees, pays attention to what he sees, appraises it, thinks about it, chooses to react to it in some way. He sometimes throws a ball or digs a ditch. We do not assume that a little man in the head pulls strings to make us see, make us dig ditches or throw a ball -- why should we need a homunculus to attend to something, to remember, to think?
To insist that human behavior is the result of learned executive routines is to indulge in a double analogy, from man to machine and from machine to man. Executive routines are instructions directing computer searches, on the analogy of a human being directing himself or others to investigate a particular area of interest. Instead of assuming that the human being uses executive routines, it is much simpler and closer to human experience to assume that we use various functions to deal with the world around us. When we do that, the only problem left is to identify the functions needed in a particular activity.
There has never been any difficulty about obvious sensory functions. Seeing, hearing, smelling, touching, and tasting have always been accepted as something we do -- except for early behaviorists who admitted responses to stimuli, but not the perception of stimuli. But the notion of an integrative sense that enables us to see objects rather than colored patches has found few adherents until it surfaced comparatively recently in the guise of global preattentive processes ( Neisser, 1967). Yet it is obvious that the visual sense itself can only mediate color. However, special cell columns in the visual cortex have been found to respond to vertical, horizontal, and oblique lines, and to movement ( Hubel & Wiesel, 1962). Hence it is the visual cortex with its six layers that seems to mediate vis- ual form and movement. It is a reasonable inference that the feltwork of the sensory cortex mediates sensory integration and articulates the visual field in such a way that we can focus on any part of it.
The primary function of attention is not that of analyzing or integrating sensory impressions, but of focusing other functions on the area of interest. We turn toward the object of attention, look, listen, and try to discover what we can about it. In other words, attention is a desire to see, hear, taste, smell, touch, think about, and so to know something as best we may. Attention requires some kind of intuitive or deliberate, unconscious or conscious judgment that something is worth knowing or investigating. Attention can be voluntary or involuntary. Involuntary attention is based on an intuitive, unwitting appraisal: a sudden loud sound, a bright color in a dull landscape, a whiff of perfume, or an unpleasant smell, all of these can alert us and draw our attention. Voluntary attention, on the other hand, is based on a person's conscious, deliberate judgment that this particular thing is something worth knowing about. If an experimental subject is instructed to press a button every time he sees a shade of red, he attends to the visual array. He wants to know it so that he can respond to it. As long as this desire lasts, he will be "set" to notice and report the shade that fits the concept. He may see other colors but will not react to them and may not even remember them.
Posner ( 1973) allows for both preconscious and conscious perceptual processing in his model of attention. A single-channel central processing capacity represents conscious attention, and is followed by rehearsal and the choice of response. Conscious attention is made possible by two stages of perceptual processing: the encoding of the stimulus, and a comparison of the stimulus with the contents of long-term memory. In his experiments, Posner showed a target stimulus (a digit or letter) to the subject, and later an array of similar stimuli with the instruction to locate the target stimulus. According to Posner, this search and comparison is preconscious. He comments that "both the target and non-target items are subject to a memory search process but only the target item gives rise to the phenomenological experience of jumping out at the subject." (p. 41.) But there is considerable doubt that this experience of the stimulus jumping out at the subject is the result of a comparison of each array stimulus with the remembered target stimulus. Indeed, research findings seem to be against such an assumption. For instance, Sternberg ( 1975) had his subjects commit a set of stimuli (letters, digits, figures) to memory; he called this the "positive set." He then showed a single test stimulus and asked his subjects to press one switch if the test stimulus was a member of the positive set, another if it was not. Sternberg found that the reaction time was so short that the subjects must have made about thirty comparisons per second, a rate considerably faster than the rate of subvocal speech which might have to be used for such comparisons. Sternberg also reported that the subjects were not aware of any search or comparison. Apparently the test stimulus simply felt familiar.
This is a prime example of an assumption based on a computer analogy: because the computer can locate the test stimulus only by search and comparison, the human being must do so, too. But the human being can recognize the test stimulus if he has seen it before (or memorized it, in Sternberg's experiment), that is, he can find it familiar. Recognition has always been considered different from recall. It is inaccessible to analysis, accounts for the target stimulus "jumping out" at the subject and is far faster than recall and comparison could ever be. In chapter 5, I discuss the difference between recall and recognition at greater length. Here, I will merely point out that recognition attracts attention (the stimulus "jumps out").
Shevrin and Dickman ( 1980) reviewed several different theories of attention and perception, all of which assume preconscious processing. A few of them also assume that such processing is qualitatively different from conscious attention. These authors suggested, on the basis of the available body of experimental research, that an initial preconscious stage of cognition is psychological (not physiological), affects conscious experience and may differ from conscious cognition in its principles of operation; conscious cognition is a later stage.
I would like to suggest that this preconscious cognition is an intuitive appraisal of something as familiar, or as good to know better because unfamiliar; this arouses a desire to turn toward it, look, listen, and investigate it. In the case of familiar objects, their recognition brings about a desire to do something about it, whether to report the occurrence or respond to it as usual. Hence attention is an appetitive and not a cognitive function. We want to turn toward the object, look, and listen. This immediately solves the problem of selective attention: all appetition implies a choice of goal, whether we want a new hat, a meal, to travel to Europe, or to look at a new car. If we attend to something, we select out of many possible things one we want to know better, whether we want to listen to a recording, watch an eclipse, or report on shades of red, locate a target stimulus, or identify the test stimulus in the positive set.
Involuntary attention, then, is the same impulse to look and listen, but based on the completely unconscious intuitive appraisal that this is unfamiliar, and should be investigated. Voluntary attention is based on a deliberate, conscious appraisal. In both cases, we have an impulse to focus on the selected object. But in voluntary attention, we want to look, in involuntary attention, we feel an urge to look.
Between Life and Death - Part I - Coma
Coma
In medicine, a coma is a profound state of unconsciousness. A person in a coma cannot be awakened, fails to respond normally to pain, light or sound, does not have sleep-wake cycles, and does not take voluntary actions. A person in a state of coma can be described as comatose.
Understanding the condition
Coma is a sleeplike state in which the patient makes no purposeful response to the environment and from which he or she cannot be aroused. The eyes are closed and do not open spontaneously. The patient does not speak, and there is no purposeful movement of the face or limbs or non-purposeful reflex movements mediated through spinal cord or brainstem pathways.
Underlying causes
Coma results from a disturbance in the function of either the brainstem reticular activating system above the midpons or of both cerebral hemispheres, since these are the brain regions that maintain consciousness.
The severity and mode of onset of coma depends on the underlying cause. For instance, deepening hypoglycemia (low blood sugar) or hypercapnia (increased carbon dioxide levels in the blood) initially cause mild agitation and confusion, then progress to obtundation, stupor and finally complete unconsciousness. In contrast, coma resulting from a severe traumatic brain injury or subarachnoid hemorrhage can be instantaneous. The mode of onset may therefore be indicative of the underlying cause.
The most crucial aspect of the history is the time over which coma develops. In the absence of precise details about the mode of onset, information about when the patient was last seen in an apparently normal state may assist in establishing the time course of the disease process.
1. A sudden onset of coma suggests a vascular origin, especially a brainstem stroke or subarachnoid hemorrhage.
2. Rapid progression from hemispheric signs, such as hemiparesis, hemisensory deficit, or aphasia, to coma within minutes to hours is characteristic of intracerebral hemorrhage.
3. A more protracted course leading to coma (days to a week or more) is seen with tumor, abscess, or chronic subdural hematoma.
4. Coma preceded by a confusional state or agitated delirium, without lateralizing signs or symptoms, is probably due to a metabolic derangement.
Glasgow Coma Scale
The Glasgow Coma Scale or GCS, sometimes also known as the Glasgow Coma Score is a neurological scale which aims to give a reliable, objective way of recording the conscious state of a person, for initial as well as continuing assessment. The scale was published in 1974 by Graham Teasdale and Bryan J. Jennett, professors of neurosurgery at the University of Glasgow. The scale comprises three tests: eye, verbal and motor responses.
Progress
Outcomes range from recovery to death. Comas generally last a few days to a few weeks, rarely more than 2 to 5 weeks but it can last as long as several years. Rarely it lasts longer but it is possible.
According to the Guinness Book of Records, the longest period spent in coma was by Elaine Esposito. She did not wake up after being anaesthetized for an appendectomy on August 6, 1941, at age 6. She died on November 25 1978 at age 43 years 357 days, having been in a coma for 37 years 111 days.
People may emerge from a coma with a combination of physical, intellectual and psychological difficulties that need special attention. Recovery usually occurs gradually patients acquire more and more ability to respond. Some patients never progress beyond very basic responses, but many recover full awareness. Regaining consciousness is not instant: in the first days, patients are only awake for a few minutes, and duration of time awake gradually increases.
References
Medical Encyclopedia from Mobile Reference
Clinical Neurology, 7e, Roger P. Simson, MD, David A. Greenberg, MD, PHD
Friday, June 18, 2010
Notes from book - Memory and brain - Chapter Perception
Question - Violet Claim - Red Evidence - Blue Assumption - Green Constraint - Yellow
It is generally agreed that sensory experience depends on selective attention.
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.
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.
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Claim : Sensory experience depends on selective attention
Assumption : To attend and object it must be a percivable and must stand out.
Claim : Integration of senses are necessary for perception. Integration is direct, unpercieved and preattentive.
Claim : Individual senses cannot convey integrated experience
Evidence : by observation of sound comes from the man playing the violin.
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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.
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.
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Claim : The stimulus recieved from various senses must be associated and integrated for making meaningful perception of an object or environment. Not only that they must also be articulated (seperately conceptualized in parts) before we percieve.
Claim : 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.
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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.
VISUAL SPACE
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.
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Claim : Location and placement of an object and the estimation of distance there from requires various cues from different sensory organs.
Claim : accurate perception of distance demands experience and memory.
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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.
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Claim : To move around in a locality we require to have a Map of the environment so that we can use spatial concepts without difficulty. It is in form of a structure of objects in various directions and at various distances from themselves, measured by the time it takes to walk to them.
Evidence is in blue
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for instance, that such patients (blind presons who regained their sight) 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.
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Claim : To develop perception people need to connect their various sensations / sinals received from different sources then store them and then connect the stored sensations and images to develop different concepts.
Evidence : 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
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CONSCIOUSNESS, MEMORY AND PERCEPTION
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Claim : Every perceptual experience presupposes awareness; and awareness is impossible without memory
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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.
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).
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Claim : 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.
Claim : Cosciousness is necessary for perception
Evidence : 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.
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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.
It seems clear that brain function has been disturbed in such cases and has brought about an interference with the spontaneous continuous recall needed for remembering what is happening and what we are doing in our daily life. Delirium, brain damage, electroshock, and concussion, represent such an obvious interference with normal brain function that we may well ask ourselves whether psychosis might not also have the same effect
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Claim : To be conscious a person need to be able to remember
Evidence : In cases where brain functions are disturbed there develops some interference in the process of contenuous recall needed for remembering what has been happening in and what we are doing in our daily life.
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When we try to identify the processes used in perception, we find that we must be aware of a situation, attend to it, and identify it by recalling similar situations. Often, when memory fails, we imagine what must have happened to fill the gaps. We can recall and imagine something seen or heard, even smelled, tasted or touched. We may need the help of visual images to form a memory image of what it feels like to touch velvet, what a good steak tastes like, or to re-experience the fragrance of a rose. Still, these memories are not pure visual images; they are also touch, taste, and olfactory images. We could call this type of recall modality-specific memory.
In addition, we evaluate perceptual experiences. We appraise the situation as good or bad for us, as beneficial or harmful, to be approached or avoided. This appraisal also draws upon memory, both on the recall of specific similar instances, but also on past appraisals. What we have found pleasant in the past, we will find pleasant when we meet something similar. We could call this immediate positive or negative reaction to something affective memory. This type of memory is immediate, spontaneous, and non-deliberate, while modality-specific memory may be recalled spontaneously or deliberately. Ordinarily, affective memory accompanies modality-specific recall. But it may happen that we instantly (we often say, "instinctively") like or dislike something or someone without any conscious memory of having had such an encounter before.
we have no habitual way of dealing with the situation, we make a guess what to expect from it. This requires imagining possible situations and possible ways of dealing with them. The choice of what we judge the best alternative leads to a particular response.
Since perception involves different activities in a specific sequence, we have to look for structures and pathways that mediate each of these activities, one after the other, rather than looking for particular "memory centers."
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Summary
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It is generally agreed that sensory experience depends on selective attention.
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.
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.
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Claim : Sensory experience depends on selective attention
Assumption : To attend and object it must be a percivable and must stand out.
Claim : Integration of senses are necessary for perception. Integration is direct, unpercieved and preattentive.
Claim : Individual senses cannot convey integrated experience
Evidence : by observation of sound comes from the man playing the violin.
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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.
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.
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Claim : The stimulus recieved from various senses must be associated and integrated for making meaningful perception of an object or environment. Not only that they must also be articulated (seperately conceptualized in parts) before we percieve.
Claim : 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.
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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.
VISUAL SPACE
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.
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Claim : Location and placement of an object and the estimation of distance there from requires various cues from different sensory organs.
Claim : accurate perception of distance demands experience and memory.
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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.
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Claim : To move around in a locality we require to have a Map of the environment so that we can use spatial concepts without difficulty. It is in form of a structure of objects in various directions and at various distances from themselves, measured by the time it takes to walk to them.
Evidence is in blue
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for instance, that such patients (blind presons who regained their sight) 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.
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Claim : To develop perception people need to connect their various sensations / sinals received from different sources then store them and then connect the stored sensations and images to develop different concepts.
Evidence : 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
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CONSCIOUSNESS, MEMORY AND PERCEPTION
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Claim : Every perceptual experience presupposes awareness; and awareness is impossible without memory
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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.
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).
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Claim : 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.
Claim : Cosciousness is necessary for perception
Evidence : 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.
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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.
It seems clear that brain function has been disturbed in such cases and has brought about an interference with the spontaneous continuous recall needed for remembering what is happening and what we are doing in our daily life. Delirium, brain damage, electroshock, and concussion, represent such an obvious interference with normal brain function that we may well ask ourselves whether psychosis might not also have the same effect
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Claim : To be conscious a person need to be able to remember
Evidence : In cases where brain functions are disturbed there develops some interference in the process of contenuous recall needed for remembering what has been happening in and what we are doing in our daily life.
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When we try to identify the processes used in perception, we find that we must be aware of a situation, attend to it, and identify it by recalling similar situations. Often, when memory fails, we imagine what must have happened to fill the gaps. We can recall and imagine something seen or heard, even smelled, tasted or touched. We may need the help of visual images to form a memory image of what it feels like to touch velvet, what a good steak tastes like, or to re-experience the fragrance of a rose. Still, these memories are not pure visual images; they are also touch, taste, and olfactory images. We could call this type of recall modality-specific memory.
In addition, we evaluate perceptual experiences. We appraise the situation as good or bad for us, as beneficial or harmful, to be approached or avoided. This appraisal also draws upon memory, both on the recall of specific similar instances, but also on past appraisals. What we have found pleasant in the past, we will find pleasant when we meet something similar. We could call this immediate positive or negative reaction to something affective memory. This type of memory is immediate, spontaneous, and non-deliberate, while modality-specific memory may be recalled spontaneously or deliberately. Ordinarily, affective memory accompanies modality-specific recall. But it may happen that we instantly (we often say, "instinctively") like or dislike something or someone without any conscious memory of having had such an encounter before.
we have no habitual way of dealing with the situation, we make a guess what to expect from it. This requires imagining possible situations and possible ways of dealing with them. The choice of what we judge the best alternative leads to a particular response.
Since perception involves different activities in a specific sequence, we have to look for structures and pathways that mediate each of these activities, one after the other, rather than looking for particular "memory centers."
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Summary
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Thursday, June 17, 2010
Memory - The functional aspects
What is memory ?
Memory is a mechanism through which retain information acquired during our lifetime. This may be our day to day learning or the sensory inputs we receive from outside environments.
Memory does not comprise a single unitary system, but rather an array of interacting systems, each capable of encoding or registering information, storing it, and making it available by retrieval. Without this capability for information storage, we could not perceive adequately, learn from our past, understand the present, or plan for the future.
What are the various types of memory from functional point of view ?
Memory has many sub divisions or types depending on the kind of function that is done by the brain. Some of them are given below ..
Sensory memory : In order to see a continuously moving image it is necessary for the brain's visual system to store the information from rom one frame until the arrival of the next. The visual store responsible for this is one of a whole series of sensory memory systems that are intimately involved in our perception of the world.
An analogous series of sensory memories occurs in hearing. If a nine digit telephone number is read in front of someone. And then he is asked to repeat it, he likely to repeat it right. But if he is asked to write it he is likely to make errors. The greater number of such telephone number will likely to increase the number of errors he makes. However here the objective is to explain that when we remember the sound patter it is easier to repeat but converting the representation of sound pattern to visual pattern increases the likelyhood of errors.
Our system has a system of storage and retrival for other senses in the same way.
Short term memory : Short-term memory (or "primary" or "active memory") is the capacity for holding a small amount of information in mind in an active, readily available state for a short period of time.
Working memory : In both language comprehension and arithmetic, therefore, there is a need for the temporary storage of information in order to perform various functions subsidiary to understanding or calculating. Once the task has been achieved, the subsidiary information is no longer required. We call it working memory.
Working memory is the executive and attentional aspect of short-term memory involved in the interim integration, processing, disposal, and retrieval of information. This forms a small intermediate storage like one we use in computers.
Long term memory : Long term memory can store information for few days to decades or even for the lifetime. Short-term memory is a temporary potentiation of neural connections which can become long-term memory through the process of rehearsal and meaningful association. This represents information that is stored for considerable periods of time. Indeed, some theorists claim that information in memory never disappears, but simply becomes less and less accessible.
Remembering your own name, how to speak, where you lived as a child, or where you were last year or indeed five minutes ago are all assumed to depend on long-term memory. Such memory is primarily concerned with storing information, unlike sensory memory and short-term memory where the storage is an incidental feature of other aspects of the system.
Implicit memory : People rely on implicit memory every day in the form of procedural memory, the type of memory that allows people to remember how to tie their shoes or ride a bicycle without consciously thinking about these activities.
Implicit memory is a type of memory in which previous experiences aid in the performance of a task without conscious awareness of these previous experiences (Schacter, 1987). Evidence for implicit memory arises in priming, a process whereby subjects show improved performance on tasks for which they have been subconsciously prepared (Graf and Mandler, 1984).
Explicit memory : Explicit memory is the conscious, intentional recollection of previous experiences and information. We use explicit memory throughout the day, such as remembering the time of an appointment or recollecting an event from years ago. Whatever we can remember when we try to recollect is explicit memory.
Decliarative memory : Declarative memory is the aspect of human memory that stores facts. It is so called because it refers to memories that can be consciously discussed, or ''declared.'' It applies to standard textbook learning and knowledge, as well as memories that can be 'travelled back to' in one's 'mind's eye'. It is contrasted with procedural memory, which applies to skills. Declarative memory is subject to forgetting, but frequently-accessed memories can last indefinitely.
Semantic memory : Semantic memory refers to the memory of meanings, understandings, and other concept-based knowledge unrelated to specific experiences. The conscious recollection of factual information and general knowledge about the world is generally thought to be independent of context and personal relevance.
Episodic memory : Episodic memory refers to the memory of events, times, places, associated emotions, and other conception-based knowledge in relation to an experience. Semantic and episodic memory together make up the category of declarative memory, which is one of the two major divisions in memory.
Procedural memory : Refers to the use of objects or movements of the body, such as how exactly to use a pencil or ride a bicycle. While speaking what muscle movements are t be done in what sequence.
Spatial memory : spatial memory is the part of memory responsible for recording information about one's environment and its spatial (pertaining to space and location with respecto external environment) orientation. For example, a person's spatial memory is required in order to navigate around a familiar city.
Other important functions associated with memory ..
Memory plays a big role in our learning process. We will never be able to think if we are stuck in the present. Even for doing the next immediate task we have to associate with our previously done tasks. There are few very important functions which are assoiated with memory are listed below…
Language learning .. The way we learn and process language very much depends on certain basic abilities we have. Any language has its own set of sounds, vocabularies, grammar and the way we reproduce the language.
Vocabulary and Grammar : This is where the ability remember and select of words comes into play.
Language perception : When we listen to others .. we need to understand what they mean. We remember the experiences of our life, compare with beliefs and values and the make sense of what is being spoken about.
On the other side if we have to say something then we need to first make ourselves ready for that action by preparing to make sense whatever we going to communicate on.
Speech motor movements : When we try to express ourselves we have to make sounds and these sounds come after you re-execute the learned movements. It is purely a function of memory and brain. Our brain control the movements that we make for producing the sound,
Association : Every piece of information in our memory is connected to other pieces in some way or another. For example, if you are given the word "apple", what do you think of? Perhaps something like this: APPLE: red, round, sweet, teacher, tree, fruit. This property of memory is known as memory association.
Recognition : Our brain is capable of associate past experiences, learnings and sensory signals to the received inputs from our sensory organs and create perceptions which helps us in recognition of objects, faces, pictures etc.
Brain mapping for memory functions : Scientists and neurologists have come to know lot about our brain functions by making a functional map of brain. It was observed by them that certain specific functions are impaired when some lesions (abnormality/damage) have formed in specific part of brain. Thus most of our present knowledge of brain functions have been contributed by study of brain damaged persons.
Scientists have tried to map all of the memory functions discussed above one or more areas of the brain. We have been able to study brain functions and mappings with the help of medical equipments producing various kind of images during execution of specific tasks. In this process we try to access which of the brain ares are activated during a specific type of activity is performed.
Brain mapping may be dealt as a seperate topic in more detailed way in another article.
References
http://en.wikipedia.org/
Biological Psychology, 10e by James W. Kalat
Essentials of Human Memory, Alan D. Baddeley
Medical Encyclopedia from MobileReference
Memory is a mechanism through which retain information acquired during our lifetime. This may be our day to day learning or the sensory inputs we receive from outside environments.
Memory does not comprise a single unitary system, but rather an array of interacting systems, each capable of encoding or registering information, storing it, and making it available by retrieval. Without this capability for information storage, we could not perceive adequately, learn from our past, understand the present, or plan for the future.
What are the various types of memory from functional point of view ?
Memory has many sub divisions or types depending on the kind of function that is done by the brain. Some of them are given below ..
Sensory memory : In order to see a continuously moving image it is necessary for the brain's visual system to store the information from rom one frame until the arrival of the next. The visual store responsible for this is one of a whole series of sensory memory systems that are intimately involved in our perception of the world.
An analogous series of sensory memories occurs in hearing. If a nine digit telephone number is read in front of someone. And then he is asked to repeat it, he likely to repeat it right. But if he is asked to write it he is likely to make errors. The greater number of such telephone number will likely to increase the number of errors he makes. However here the objective is to explain that when we remember the sound patter it is easier to repeat but converting the representation of sound pattern to visual pattern increases the likelyhood of errors.
Our system has a system of storage and retrival for other senses in the same way.
Short term memory : Short-term memory (or "primary" or "active memory") is the capacity for holding a small amount of information in mind in an active, readily available state for a short period of time.
Working memory : In both language comprehension and arithmetic, therefore, there is a need for the temporary storage of information in order to perform various functions subsidiary to understanding or calculating. Once the task has been achieved, the subsidiary information is no longer required. We call it working memory.
Working memory is the executive and attentional aspect of short-term memory involved in the interim integration, processing, disposal, and retrieval of information. This forms a small intermediate storage like one we use in computers.
Long term memory : Long term memory can store information for few days to decades or even for the lifetime. Short-term memory is a temporary potentiation of neural connections which can become long-term memory through the process of rehearsal and meaningful association. This represents information that is stored for considerable periods of time. Indeed, some theorists claim that information in memory never disappears, but simply becomes less and less accessible.
Remembering your own name, how to speak, where you lived as a child, or where you were last year or indeed five minutes ago are all assumed to depend on long-term memory. Such memory is primarily concerned with storing information, unlike sensory memory and short-term memory where the storage is an incidental feature of other aspects of the system.
Implicit memory : People rely on implicit memory every day in the form of procedural memory, the type of memory that allows people to remember how to tie their shoes or ride a bicycle without consciously thinking about these activities.
Implicit memory is a type of memory in which previous experiences aid in the performance of a task without conscious awareness of these previous experiences (Schacter, 1987). Evidence for implicit memory arises in priming, a process whereby subjects show improved performance on tasks for which they have been subconsciously prepared (Graf and Mandler, 1984).
Explicit memory : Explicit memory is the conscious, intentional recollection of previous experiences and information. We use explicit memory throughout the day, such as remembering the time of an appointment or recollecting an event from years ago. Whatever we can remember when we try to recollect is explicit memory.
Decliarative memory : Declarative memory is the aspect of human memory that stores facts. It is so called because it refers to memories that can be consciously discussed, or ''declared.'' It applies to standard textbook learning and knowledge, as well as memories that can be 'travelled back to' in one's 'mind's eye'. It is contrasted with procedural memory, which applies to skills. Declarative memory is subject to forgetting, but frequently-accessed memories can last indefinitely.
Semantic memory : Semantic memory refers to the memory of meanings, understandings, and other concept-based knowledge unrelated to specific experiences. The conscious recollection of factual information and general knowledge about the world is generally thought to be independent of context and personal relevance.
Episodic memory : Episodic memory refers to the memory of events, times, places, associated emotions, and other conception-based knowledge in relation to an experience. Semantic and episodic memory together make up the category of declarative memory, which is one of the two major divisions in memory.
Procedural memory : Refers to the use of objects or movements of the body, such as how exactly to use a pencil or ride a bicycle. While speaking what muscle movements are t be done in what sequence.
Spatial memory : spatial memory is the part of memory responsible for recording information about one's environment and its spatial (pertaining to space and location with respecto external environment) orientation. For example, a person's spatial memory is required in order to navigate around a familiar city.
Other important functions associated with memory ..
Memory plays a big role in our learning process. We will never be able to think if we are stuck in the present. Even for doing the next immediate task we have to associate with our previously done tasks. There are few very important functions which are assoiated with memory are listed below…
Language learning .. The way we learn and process language very much depends on certain basic abilities we have. Any language has its own set of sounds, vocabularies, grammar and the way we reproduce the language.
Vocabulary and Grammar : This is where the ability remember and select of words comes into play.
Language perception : When we listen to others .. we need to understand what they mean. We remember the experiences of our life, compare with beliefs and values and the make sense of what is being spoken about.
On the other side if we have to say something then we need to first make ourselves ready for that action by preparing to make sense whatever we going to communicate on.
Speech motor movements : When we try to express ourselves we have to make sounds and these sounds come after you re-execute the learned movements. It is purely a function of memory and brain. Our brain control the movements that we make for producing the sound,
Association : Every piece of information in our memory is connected to other pieces in some way or another. For example, if you are given the word "apple", what do you think of? Perhaps something like this: APPLE: red, round, sweet, teacher, tree, fruit. This property of memory is known as memory association.
Recognition : Our brain is capable of associate past experiences, learnings and sensory signals to the received inputs from our sensory organs and create perceptions which helps us in recognition of objects, faces, pictures etc.
Brain mapping for memory functions : Scientists and neurologists have come to know lot about our brain functions by making a functional map of brain. It was observed by them that certain specific functions are impaired when some lesions (abnormality/damage) have formed in specific part of brain. Thus most of our present knowledge of brain functions have been contributed by study of brain damaged persons.
Scientists have tried to map all of the memory functions discussed above one or more areas of the brain. We have been able to study brain functions and mappings with the help of medical equipments producing various kind of images during execution of specific tasks. In this process we try to access which of the brain ares are activated during a specific type of activity is performed.
Brain mapping may be dealt as a seperate topic in more detailed way in another article.
References
http://en.wikipedia.org/
Biological Psychology, 10e by James W. Kalat
Essentials of Human Memory, Alan D. Baddeley
Medical Encyclopedia from MobileReference
Why blogging?
I will do blogging for personal growth .. It is one of the best way to record day to day events .. working. It may serve as a personal diary. It can also serve as a scrap book to store useful information. Initially I am planning to have two blogs .. the first one is for just recording ideas and preliminary workings on any article or subject. The second blog will be for keeping the final works after cleaning. The articles or messages published there would be put into various specialized groups for verification and comments. There may be other blogs also depending on which subject or what audience I am preparing it for.
The personal blog will be open to people who I consider to be contributing in the working process with their opinion and comments.
The personal blog will be open to people who I consider to be contributing in the working process with their opinion and comments.
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