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memory

  (mĕm'ə-rē) pronunciation
n., pl. -ries.
  1. The mental faculty of retaining and recalling past experience.
  2. The act or an instance of remembering; recollection: spent the afternoon lost in memory.
  3. All that a person can remember: It hasn't happened in my memory.
  4. Something remembered: pleasant childhood memories.
  5. The fact of being remembered; remembrance: dedicated to their parents' memory.
  6. The period of time covered by the remembrance or recollection of a person or group of persons: within the memory of humankind.
  7. Biology. Persistent modification of behavior resulting from an animal's experience.
  8. Computer Science.
    1. A unit of a computer that preserves data for retrieval.
    2. Capacity for storing information: two gigabytes of memory.
  9. Statistics. The set of past events affecting a given event in a stochastic process.
  10. The capacity of a material, such as plastic or metal, to return to a previous shape after deformation.
  11. Immunology. The ability of the immune system to respond faster and more powerfully to subsequent exposure to an antigen.

[Middle English memorie, from Anglo-French, from Latin memoria, from memor, mindful.]


 
 

The ability to store and access information that has been acquired through experience. Memory is a critical component of practically all aspects of human thinking, including perception, learning, language, and problem solving. See also Perception.

Stages

The information-processing approach divides memory into three general stages: sensory memory, short-term memory, and long-term memory. Sensory memory refers to the sensations that briefly continue after something has been perceived. Short-term memory includes all of the information that is currently being processed in a person's mind, and is generally thought to have avery limited capacity. Long-term memory is where all the information that may be used at a later time is kept.

A number of interesting facts are known about sensory memory, including the following: (1) sensory memories appear to be associated with mechanisms in the central nervous system rather than at the sensory receptor level, and (2) the amount of attention that a person pays to a stimulus can affect the duration of the sensory memory. Although all of the functions of sensory memory are not understood, one of its most important purposes is to provide people with additional time to determine what should be transferred to the next stage in the memory system, that is, short-term memory.

Information obtained from either sensory memory or long-term memory is processed in short-term memory in order for a person to achieve current goals. In some situations, short-term memory processing simply involves the temporary maintenance of a piece of information, such as remembering a phone number long enough to dial it. Other times, short-term memory can involve elaborate manipulations of information in order to generate new forms. For example, when someone reads 27 + 15, the person manipulates the symbols in short-term memory in order to come up with the solution. One useful manipulation that can be done in short-term memory is to reorganize items into meaningful chunks. For example, it is a difficult task to keep the letters S K C A U Q K C U D E H T in mind all at once. However, if they are rearranged in short-term memory, in this case reversing them, they can be reduced to a single simple chunk: THE DUCK QUACKS. Short-term memory can accommodate only five to seven chunks at any one time. However, the amount of information contained in each chunk is constrained only by one's practice and ingenuity. In order to increase the amount of information that can be kept in short-term memory at one time, people need to develop specific strategies for organizing that information into meaningful chunks. In addition, many studies have also demonstrated that the transfer of information from short-term to long-term memory is much greater when the information is manipulated rather than simply maintained.

One can keep massive amounts of information in long-term memory. In general, recall from long-term memory simply involves figuring out the heading under which a memory has been filed. Many tricks for effective retrieval of long-term memories involve associating the memory with another more familiar memory that can serve as an identification tag. This trick of using associations to facilitate remembering is called mnemonics. Long-term memory stores related concepts and incidents in close range of one another. This logical association of memories is indicated by subjects' reaction times for identifying various memories. Generally, people are faster at recalling memories if they have recently recalled a related memory. One good way to locate a long-term memory is to remember the general situation under which it was stored. Accordingly, techniques that reinstate the context of a memory tend to facilitate remembering.

Sometimes information may not have been filed in long-term memory in the first place, or if it has, is inaccessible. In these situations, the long-term memory system often fills in the gaps by using various constructive processes. One common component to memory constructions is a person's expectations. Countless studies have also indicated that memories tend to systematically change in the direction of a prior expectation or inference about what is likely to have occurred.

Physiology

A number of physiological mechanisms appear to be involved in the formation of memories, and the mechanisms may differ for short-term and long-term memory. There is both direct and indirect evidence suggesting that short-term memory involves the temporary circulation of electrical impulses around complex loops of interconnected neurons. A number of indirect lines of research indicate that short-term memories are eradicated by any event that either suppresses neural activity (for example, a blow to the head or heavy anesthesia) or causes neurons to fire incoherently (for example, electroconvulsive shock). More direct support for the electric circuit model of short-term memory comes from observing electrical brain activity. By implanting electrodes in the brain of experimental animals, researchers have observed that changes in what an animal is watching are associated with different patterns of circulating electrical activity in the brain. These results suggest that different short-term memories may be represented by different electrical patterns. However, the nature of these patterns is not well understood. See also Electroencephalography.

Long-term memories appear to involve some type of permanent structural or chemical change in the composition of the brain. This conclusion is derived both from general observations of the imperviousness of long-term memories and from physiological studies indicating specific changes in brain composition. Even in acute cases of amnesia where massive deficits in long-term memory are reported, often, with time, all long-term memories return. Similarly, although electroconvulsive therapy is known to eliminate recent short-term memories, it has practically no effect on memories for events occurring more than an hour prior to shocking. Thus the transfer from a fragile short-term memory to a relatively solid long-term memory occurs within an hour. This process is sometimes called consolidation. See also Electroconvulsive therapy.

The nature of the “solid” changes associated with long-term memories appears to involve alterations in both the structural (neural connections) and chemical composition of the brain. One study compared the brains of rats that had lived either in enriched environments with lots of toys or in impoverished environments with only an empty cage. The cerebral cortices of the brains of the rats from the enriched environment were thicker, heavier, endowed with more blood vessels, and contained significantly greater amounts of certain brain chemicals (such as the neurotransmitter acetylcholine). Other researchers have observed that brief, high-frequency stimulation of a neuron can produce long-lasting changes in the neuron's communications across synapses.

Researchers believe that different brain structures may be involved in the formation and storage of long-term memories. The hippocampus, thalamus, and amygdala are believed to be critical in the formation of long-term memories. Individuals who have had damage to these structures are able to recall memories prior to the damage, indicating that long-term memory storage is intact; however, they are unable to form new long-term memories, indicating that the long-term memory formation process has been disrupted. It is not known where long-term memories are stored, but they may be localized in the same areas of the brain that participated in the actual learning. See also Brain.


 

The computer's workspace, which is physically a collection of dynamic RAM (DRAM) chips. It is a major resource in the computer because it determines the size and number of programs that can be run at the same time, as well as the amount of data that can be processed instantly.

It All Takes Place in Memory

All program execution and data processing takes place in memory, often called "main memory" to differentiate it from memory chips on other circuit boards in the machine. The program's instructions are copied into memory from disk, tape or from the network and then extracted from memory into the control unit circuit for analysis and execution. The instructions direct the computer to input data into memory from a keyboard, disk, tape, modem or network.

Calculate, Compare and Copy

As data are entered into memory, the previous contents of that space are lost. Once the data are in memory, they can be processed (calculated, compared and copied). The results are sent to a screen, printer, disk, tape, modem or network.

An Electronic Checkerboard

Memory is like an electronic checkerboard, with each square holding one byte of data or instruction. Each square has a separate address like a post office box and can be manipulated independently. As a result, the computer can break apart programs into instructions for execution and data records into fields for processing. See early memories and RAM.

A Checkerboard of Bytes
Each checkerboard square of memory holds one byte. The contents of any single byte or group of bytes can be calculated, compared and copied independently. That is how fields are put together to form records and broken apart when read back in. On a disk, data are stored in sectors, typically 512 bytes long, that are the smallest unit that can be read or written by the drive.

Memory Does Not Remember

Oddly enough, the computer's memory does not "remember" anything when the power is turned off. So why do they call it memory? Because the first memory did "remember," but today's RAM chips do not, which is why files have to be saved before the application is ended. Although there are memory chips that do hold their content permanently (ROMs, PROMs, EPROMs, Flash, etc.), they are used for internal control purposes and not for the user's data. Just to bewilder you more, it is quite possible that in the future, memory will again "remember" (see future RAM chips).

"Remembering" memory in a computer system is its disks and tapes, and although they are sometimes called "memory devices," many prefer to call them "storage devices" (as we do) in order to differentiate them from internal memory.

Memory Can Get Clobbered!

Memory is an important resource that cannot be wasted. It must be allocated by the operating system as well as by applications and then released when not needed. Errant programs can grab memory and not let go of it, which results in less and less memory available as you load and use more programs. Restarting the computer gives memory a clean slate, which is why rebooting the computer clears up so many problems with applications.

In addition, if the operating system has bugs, a malfunctioning application can write into the same memory used by another program, causing all kinds of unspecified behavior. You discover it when the system freezes or something weird happens all of a sudden. If you were to be able to look into memory and watch how fast data and instructions are written into and out of it in the course of even 10 minutes, you would know it is truly a miracle that it works at all.

Other terms for the computer's main memory are RAM, primary storage and read/write memory. Earlier terms were core and core storage. See dynamic RAM, static RAM and memory module.



 

Space within a computer where information and program are stored while being actively worked on; also called core. It is expressed in terms of the number of characters (Bytes) that can be retained. The memory of the computer is in the form of read-only (ROM) and Ram (Random-Access Memory) or read/write memory. It is this memory facility that distinguishes the computer from devices such as calculators and bookkeeping machines, which, although they have input, output, and processing capabilities, cannot store programs internally within the processing unit.

 

Life is unpredictable. But memory provides organisms with the ability to learn — to modify their behaviour in the light of experience — and hence to reduce their uncertainty about the world. This is clearly an important behavioural adaptation, from the point of view of evolution. Indeed, most animals exhibit some forms of learning and memory, ranging all the way from gradual weakening (habituation) or strengthening (sensitization) of simple reflex actions, to conscious recollection of personal experiences.

We can remember a telephone message for the few seconds it takes to write it down. But we can also remember things over very long periods of time. For example, adults may still remember some of the things they were taught at school — both general abilities, such as how to add numbers together, and specific things, such as the translation of ‘la plume de ma tante’. Additionally, we can also remember (though unconsciously) many of the skills attained through life, such as how to ride a bicycle or play the piano. There are many different ways in which humans and other animals remember things. It follows that memory cannot be conceptualized simply and that there are likely to be a variety of different, interacting memory systems.

Much of our sense of who we are as individuals depends on a particular kind of memory, involving recollection of our own past experiences, feelings, and relationships. One only has to imagine not being able to recall what has happened in one's past, or whether or not one even has family and friends, to realize how disruptive and distressing severe amnesia (such as occurs in Alzheimer's disease) can be, both to the patients themselves and to those close to them.

Psychologists have long drawn distinctions between different types of memory systems and memory processes. As early as 1890 William James distinguished between ‘primary memory’ (information one is presently aware of) and ‘secondary memory’ (information in the psychological past). Current ideas still maintain a distinction between short-term memory and long-term memory, evidenced by impairments of one or the other in brain-damaged patients. However, early ‘multistore models’, which proposed separate short-term and long-term memory stores, have now been discredited as being too simplistic.

The idea of a unitary short-term store has now largely been replaced by the concept of ‘working memory’. The working memory system is concerned with both active processing and short-term storage of information and allows one to plan for the future and to bring together thoughts and ideas. Damage to the frontal lobes seems to impair working memory: patients with such damage function rather normally apart from being impaired in the use of stored knowledge to guide appropriate behaviour. Experiments on monkeys have shown that individual nerve cells in certain parts of the frontal cortex not only fire impulses when certain objects are seen by the monkey but continue to respond when the object disappears from view, as if holding a memory of the object. Furthermore, studies on the effects of damage of the frontal lobes in monkeys suggest that different forms of working memory can be localized to specific regions of the prefrontal cortex — the front part of the frontal lobes.

The concept of a single long-term store has also been replaced, by the view that there are several interacting long-term memory systems. There have been many attempts to subdivide long-term memory, but none has proved entirely successful. Another early distinction was between ‘episodic memory’ and ‘semantic memory’. Episodic memory is autobiographical recollection of personally experienced events (such as what you had for breakfast), whereas semantic memory is general knowledge about the world, factual information and its meaning (such as the fact that breakfast is a kind of meal). Despite a clear conceptual difference, there is less evidence that these two types of memory rely on different memory systems in the brain. Indeed, semantic and episodic memory would appear to be strongly interdependent. For instance, retrieving semantic information may depend upon recalling the particular episodic event or events during which the semantic knowledge was gained. Likewise, it has been argued that recalling an episodic event (for example, remembering seeing an elephant at the zoo) depends on intact semantic memory (the definition of an elephant). Both types of memory may therefore rely on common underlying neural structures.

An alternative distinction was made between ‘declarative memory’ and ‘procedural memory’. Declarative memory refers to knowing ‘what’, and includes both semantic and episodic information, whereas procedural memory refers to knowing ‘how’, and relates to skilled behaviour without the need for conscious recollection, such as the ability to remember how to drive a car. Support comes from observation of certain patients with amnesia who seem to have relatively intact procedural learning abilities (they can still learn how to do things) in the face of impaired declarative learning (e.g. not remembering where they are). However, the distinction between declarative and procedural knowledge is imprecise and many kinds of behaviour involve aspects of both. Furthermore, some patients with severe amnesia are capable of certain feats of memory (such as learning new factual information) that cannot be explained by procedural learning alone.

A further theoretical distinction was made between ‘explicit memory’ and ‘implicit memory’. Explicit memory is said to be involved in tasks that require conscious recollection of previous experiences, whereas tasks that are facilitated in the absence of conscious recollection are said to depend on implicit memory. Many traditional methods used to test memory involve the person being asked to remember specific experiences, and are therefore measures of explicit memory. For instance, the memory of a previously-seen list of words could be tested by free recall (‘Tell me the words that were on that list you saw earlier’), by recognition (‘Was this word among the list you saw?’), or by cued recall (‘Complete these letters to form a word that occurred on the list’).

To demonstrate implicit memory it is necessary to show that a person has a long-term memory of a past experience although they can't consciously recall it. For example, the perceptual identification of words presented extremely briefly is easier if the words have previously been seen. Amnesic patients perform relatively normally on such ‘repetition priming’ tasks, as well as being able to acquire new motor skills, yet they are impaired on most tests of explicit memory. However, the distinction between explicit and implicit memory is again rather general and does not account for all of the patterns of long-term memory performance in amnesic subjects. Furthermore, the theory does nothing to address the fact that amnesic subjects can still form conscious short-term memories, which clearly involve explicit learning.

Observations that amnesic patients can retain some information briefly but not for long periods of time led to the development of the ‘consolidation theory’. This suggests that immediate experiences are somehow crystallized into long-term memory, and that this process is disrupted in amnesia. The theory also maintains that the process of memory consolidation occurs over a period of time, during which memory traces are particularly vulnerable to permanent disruption by such things as a blow to the head, certain drugs, electric shock to the brain, etc. However, consolidation theory cannot account for the fact that apparently lost memories can sometimes be retrieved subsequently.

‘Context-dependent theories’ on the other hand propose that each memory trace (for instance of a particular person) is encoded together with information about the associated context (where you met the person), and that subsequent retrieval of the memory may be facilitated by reinstating the context. (Everyone is familiar with the fact that it is difficult to remember the names of even close friends when you meet them in unexpected places.) This theory is supported by the remarkable observation that divers recall more words learnt underwater when subsequently tested underwater than when tested on land, and vice versa. Learning while under the influence of certain drugs is also context-dependent, being better recalled when the same drug is administered.

Related ‘state-dependent theories’ maintain that agents or procedures that induce amnesia do not permanently disrupt memories but rather ‘re-encode’ the memory traces in association with the brain state induced by the amnesic agent or procedure. Patients who have electroconvulsive shock (for instance, to treat depression) often complain of loss of memories; and this procedure indubitably disrupts long-term memory when given experimentally to rats. But rats can retrieve their lost memories after a subsequent shock, because this puts the brain back into the condition in which the information was ‘re-encoded’, thereby providing an additional cue to aid remembering.

Although it is hard to verify whether a deficiency of memory reflects re-encoding or permanent memory loss, the importance of forgetting should not be underestimated. Although the brain has a huge capacity for memories, it must be finite. Since the brain appears to be able to form associations between disparate stimuli very easily, so it is important for it to be able to forget meaningless or arbitrary associations and remember only those associations that prove consistent or relevant. It has been theorized that inappropriate associations in the brain may specifically be weakened during the phase of sleep in which rapid eye movements and vivid dreams occur (REM sleep).

It is intuitively obvious that memories of all sorts involve functional changes in the brain, sometimes occurring remarkably quickly. Much of what we know about learning and memory has been gained from clever experiments involving the training of animals, both intact and with brain damage, as well as from studies of normal and amnesic human beings. But over the past few decades neurophysiologists and molecular biologists have made great strides in their understanding of the cellular mechanisms of learning and memory. One fruitful approach has involved examining basic forms of learning in animals with relatively simple nervous systems, such as the marine snail Aplysia. This animal withdraws its gill apparatus reflexly when the ‘mantle’ around it is touched, and the circuit of sensory and motor nerve cells responsible for this has been defined. This reflex is subject to habituation (if the touch to the gill is repeated time after time), and to sensitization (if the touch is coupled with other stimulation).

It turns out that these simple forms of short-term implicit learning involve changes in the effectiveness of synaptic transmission (mainly changes in the amount of transmitter substance per nerve impulse released at a particular synapse in the circuit). Longer-term memory requires new protein synthesis and the growth of new or larger synapses.

More complicated forms of learning may involve elaboration of a common set of molecular mechanisms. For instance, most animals can learn to associate one stimulus with another (such as the association formed between the sound of a bell and the sight of food in Pavlovs' famous experiments on classical conditioning). The underlying neural change, just as for sensitization in Aplysia, is thought to involve increased release of transmitter substance at synapses in the circuit associating the two forms of stimulation.

In recent years, attention has focused on a primitive part of the cerebral cortex called the hippocampus, which is tucked inside, under the lower edge of the temporal lobe of the cerebral hemispheres. Extensive damage to this general region in humans can cause devastating retrograde amnesia, which virtually eliminates the capacity to form new long-term conscious memories, while leaving old semantic and personal memories relatively intact. Traditionally, the hippocampus itself has been considered the seat of human episodic memory. However, recent research with monkeys has revealed several, functionally dissociable memory systems in this region of the temporal lobe. These include the perirhinal cortex, for object memory, and the amygdala, for memory for the emotional significance of stimuli and events. These individual areas, each with its different specialization, may then contribute to a broader-based temporal lobe memory system providing the basis of both episodic and semantic memory. The monkey's hippocampus may have a relatively restricted role in memory for spatial location.

In rodents, the hippocampus certainly seems particularly involved in spatial memory: when it is damaged, rats and mice cannot remember their way around mazes. It turns out that the connections between certain nerve cells in the hippocampus are remarkably ‘plastic’. Synapses can be strengthened simply by a brief burst of nerve impulses, so that single impulses will subsequently (and for very long periods of time) evoke much bigger electrical responses in the receiving cell. Much is now known about the molecular basis of this phenomenon, called long-term potentiation. This mechanism may provide the basis of, or at least contribute to, many forms of learning, in several different regions of the brain, ranging from perceptual learning in young animals to human explicit memory.

Memory is central to the human condition and has been investigated at many levels. Neuroscientists have studied the molecular and cellular mechanisms of memory in animals and humans, and psychologists have contributed to our understanding about the different kinds of processes involved in memory through research with amnesic patients and normal subjects. Temporal lobe dysfunction is commonly associated with declarative or explicit memory impairments. However, since most amnesic patients either exhibit diffuse brain damage (Korsakoff's syndrome) or have focal damage to a range of different structures, our present understanding of which particular neural systems are important for different memory processes has come predominantly from animal ‘models’ of human amnesia.

— Mark J. Buckley

Bibliography

  • Bolhuis, J. (2000). Brain, perception, memory: advances in cognitive neuroscience. Oxford University Press.
  • Eysenck, M. W. (1995). Cognitive psychology: a student's handbook, (3rd edn). Erlbaum, Hove

See also amnesia; brain; cerebral cortex; limbic system.

 
Thesaurus: memory

noun

  1. The power of retaining and recalling past experience: recall, recollection, remembrance, reminiscence. See remember/forget.
  2. An act or instance of remembering: recollection, remembrance, reminiscence. See remember/forget.

 
Antonyms: memory

n

Definition: ability to hold in the mind
Antonyms: amnesia, forgetfulness, ignorance


 

n

1. the ability to recall events, experiences, information, and skills. n 2. a general term for a device that stores data in binary code on electronic or magnetic media in computers. n 3. the ability of the immune system to greatly speed up the response to pathogens that have previously been encountered.

 

Computers

In digital computers, a physical device used to store such information as data or programs on a temporary or permanent basis. Most digital computer systems have two types of memory, the main memory and one or more auxiliary storage units. In most cases, the main memory is a high-speed RAM. Auxiliary storage units include hard disks, floppy disks, and magnetic tape drives. Besides main and auxiliary memories, other forms of memory include ROM and optical storage media such as videodiscs and compact discs (see CD-ROM).

Psychology

Power or process of recalling or reproducing what has been learned or experienced. Research indicates that the ability to retain information is fairly uniform among normal individuals; what differs is the degree to which persons learn or take account of something to begin with and the kind and amount of detail that is retained. Attention, motivation, and especially association facilitate this process. Visual images are generally better remembered than are other forms of sense-data. Memory prodigies, or people with "photographic" or "eidetic" memories, often draw heavily on visual associations, including mnemonics. Many psychologists distinguish between short- and long-term memory. The former (variously said to last 10 seconds to 3 minutes) is less subject to interference and distortion than the latter. Long-term memory is sometimes divided into episodic (i.e., event-centred) and semantic (i.e., knowledge-centred) memory. Various models of memory have been proposed, from the Enlightenment notion of impressions made on brain tissues (restyled as "memory molecules" or coded "engrams" in the 20th century) to B.F. Skinner's "black box" to more recent ideas concerning information processing or the formation of neuronal groups. Disorders of or involving memory include Alzheimer disease, amnesia, Korsakoff syndrome, post-traumatic stress disorder, and senile dementia. See also hypnosis.

For more information on memory, visit Britannica.com.

 
Architecture: memory

The quality of a material that enables it to return to its original shape after it has been compressed or stretched.


 

The power of the mind to think of a past that no longer exists poses both empirical, psychological problems, and more abstract philosophical ones. The scientist wants to know how the brain stores its memories, and whether the mechanism is similar for different types of memory, such as short-term and long-term memories. The philosopher is particularly puzzled by the representative power of memory. That is, if I summon up a memory of some event, how do I know to interpret it as representing the past, rather than being a pure exercise of imagination? Is there a specific ‘feeling of pastness’? But if so, might I not then have the feeling, but not know to interpret that as a feeling of pastness? Indeed, is there always a present representation, or might memory be a form of direct acquaintance with the past? This might at least give us a justification of the confidence we place in memory. But is not the sceptical hypothesis proposed by Russell, that the earth might have sprung into existence five minutes ago, with a population that ‘remembers’ a wholly unreal past, at least logically possible? But if it is logically possible, the question of how we know that this is not what has happened is set to look intractable.

 

The mental faculty that facilitates storage and retrieval of information that has been learned, such as sport knowledge or a motor programme. According to the black box theory, memory has been viewed as consisting of three components short-term sensory store short-term memory, and long-term memory. The hippocampus of the limbic system plays an important part in memory. The exact way in which the brain stores information is unknown, but it may involve chemical or structural changes. See also engram, memory-drum theory.

Memory (Click to enlarge)
Memory
(Click to enlarge)

 
in psychology, the storing of learned information, and the ability to recall that which has been stored. It has been hypothesized that three processes occur in remembering: perception and registering of a stimulus; temporary maintenance of the perception, or short-term memory; and lasting storage of the perception, or long-term memory. Two major recognized types of long-term memory are procedural memory, involving the recall of learned skills, and declarative memory, the remembrance of specific stimuli. For long-term memory to occur, there must be a period of information consolidation.

The process of forgetting was first studied scientifically by Hermann Ebbinghaus, a German experimental psychologist, who performed memory tests with groups of nonsense syllables (disconnected syllables without associative connection). Ebbinghaus showed that the rate of forgetting is greatest at first, gradually diminishing until a relatively constant level of retained information is reached. Theories to explain forgetting include the concept of disuse, which proposes that forgetting occurs because stored information is not used, and that of interference, which suggests that old information interferes with information learned later and new information interferes with previously learned information.

In some instances, memory loss is an organic, physiological process. Retrograde amnesia, i.e., the failure to remember events preceding a head injury, is evidence of interrupted consolidation of memory. In anterograde amnesia, events occurring after brain damage—e.g., in head injury or alcoholism—may be forgotten. Memory loss may also result from brain cell deterioration following a series of strokes, cardiovascular disease, or Alzheimer's disease (see dementia).

Physiologically, learning involves modification of neural pathways. PET scans and related studies have shown certain parts of the brain, such as the frontal lobe of the cerebral cortex and a structure called the hippocampus, to be particularly active in recall. Computer models of brain memory are called neural networks. In a study using genetic manipulation, a mouse with enhanced memory capabilities has been produced.

Bibliography

See M. H. Ashcroft, Human Memory and Cognition (1989, repr. 1994); N. Cowan, Attention and Memory (1995, repr. 1998); J. McConkey, ed. The Anatomy of Memory (1996); D. L. Schacter, Searching for Memory (1996) and The Seven Sins of Memory (2001); J. A. Groegerd, Memory and Remembering (1997); A. Baddeley, Human Memory (rev. ed. 1998); R. Rupp, Committed to Memory (1998).


 

If one views memory as the ability to retain and recall past states of consciousness, then psychoanalysis has played a considerable role in its delineation. But in terms of memory theory considered more broadly, its significance is much more modest. Freud approached memory from three perspectives. In terms of neurology, his contributions were original but limited. From the standpoint of psychology, he added to the pre-existing framework. Finally, in creating the psychoanalytic perspective, Freud essentially reworked views that had been extensively discussed in philosophy, literature, and scientific research.

In 1891 Freud's On Aphasia: A Critical Study (1891b) proposed a solution to the problem of memory retrieval and disorders of memory, which was much discussed at the end of the nineteenth century following the discoveries of Paul Broca. Freud did not take sides in the dispute between Broca, who localized language function to a specific cerebral area, and Carl Wernicke, who developed the functional concept of conduction aphasia. Freud's solution, which resembled the one that Henri Bergson adopted five years later in Matter and Memory, could serve as the basis for a dialogue between neurology and philosophy. But the 1891 text is a pre-psychoanalytic work.

Freud's second, psychological perspective finds him apparently subscribing to the theory of memory traces. Already expressed in its major outlines in Plato's Theatetus, this theory was commonplace in the nineteenth century, when the vogue for scientific materialism made it seem self-evident (although spiritualists also accepted it). In this sense Freud is close to his contemporary, Théodule Ribot, but for Freud the theory of memory traces assumed a specific form intended to account for the role the unconscious plays in remembering. This led to Freud's Project for a Scientific Psychology of 1895 (1950c [1895]) and the best expression of the doctrine, in chapter 7 of The Interpretation of Dreams (1900a). The "Mystic Writing Pad" (1925a) represents an attempt to provide the theory of memory traces and process of memory retrieval with a metaphor suitable for psychoanalysis. But in these texts, Freud was concerned to place facts revealed by psychoanalysis within the framework of conventional psychological theory; he made no effort to create a new "theory of memory."

Much more familiar (and often wrongly considered as the specific psychoanalytic contribution to problems of memory) is the third perspective, involving the alleviation of pathological symptoms by recalling forgotten traumata. Freud himself did a great deal to promote this point of view through the significance he attached in numerous of his writings to Josef Breuer's treatment of Anna O. Too common is the impression that the famous formula "hysterics suffer mainly from reminiscences" (Studies on Hysteria, 1895d, p. 7) expresses the most fundamental idea in psychoanalysis.

There is no question that the idea of recollection constitutes an essential part of psychoanalytic therapy, and to think otherwise is to betray Freud in a fundamental way. Serge Viderman's claim in La Construction de l'espace analytique (1970) that the search for lost memories is one of Freud's youthful illusions to be replaced, in analysis, with co-constructions of subjectivity, is simply an attempt to employ non-analytic therapy, proposed in the past by such authors as Karen Horney. Until the end of his life Freud remained attached to this model: trauma / repression / forgetting / symptom / remembering / healing. In 1937, in "Analysis Terminable and Interminable," he went so far as to say that, like hysterics, psychotics also suffer from reminiscences, implying that certain delusional representations were, in fact, the reappearance in consciousness of past experiences unrecognized as such. Between Anna O. and this late text, Freud's entire body of work is sprinkled with thoughts along these lines. In "Remembering, Repeating and Working-Through" (1914g), for example, he resolved the conflict between impossible access to memory and the sterility of repetition through the introduction of what he called "working through" (Durcharbeitung). Further proof is found in his "A Disturbance of Memory on the Acropolis" (1936a), in which Freud displaces the memory trauma (thinking the Acropolis did not exist) onto another type of fact (fear of surpassing the father). The "search for lost time," the attempt to alleviate repression that has produced a failure of memory and the associated symptom, is one of the major themes of Freudian psychoanalysis. However, reservations are in order regarding its originality and theoretical scope.

Even though Freud often felt that the cure for hysterical symptoms through recollection of repressed traumatic memories could be presented as a revolutionary discovery, such figures as Janet and other late nineteenth-century psychotherapists viewed the idea and even the method as commonplace. The idea can even be traced back much further. For example, in a letter to Pierre Chanut, dated June 6, 1647, René Descartes recounts that his penchant for girls with a squint came to an end with his recollection of a childhood memory. Descartes's interest in such women may not have been a true hysterical symptom, but the link between current behavior and its origin in the past is indicated along with all the characteristics (forgetting, unconsciousness, healing through remembrance) that Freud would later employ. Much earlier, Plato, in the Phaedrus, interpreted the process of falling in love in a similar manner. In short, there is no end to the number of literary, philosophical, and clinical sources for what is often considered the most significant psychoanalytic contribution to the theory of memory.

More plausibly, psychoanalysis lent to a certain type of amnesia and memory retrieval an unanticipated practical (therapeutic) scope. Its importance was practical. Although it constitutes an original theoretical point, it does not amount to a global theory such as those developed by philosophers and psychologists. However, it has a good fit with such theories. It works, for example, within the framework that Henri Bergson described and interpreted in Matter and Memory.

Bibliography

Bergson, Henri. (1896). Matter and memory. New York: Zone Books, 1988.

Freud, Sigmund. (1891b). On aphasia; A critical study. New York: International Universities Press, 1953.

——. (1900a). The interpretation of dreams. Part I, SE,4: 1-338; Part II, SE, 5; 339-625.

——. (1914g). Remembering, repeating and working-through (Further recommendations on the technique of psycho-analysis II). SE, 12: 145-156.

——. (1925a). A note upon the "mystic writing pad." SE, 19: 225-232.

——. (1936a). A disturbance of memory on the Acropolis. SE, 22: 239-248 ——. (1937c). Analysis terminable and interminable. SE, 23: 209-253

—YVON BRÈS

 

The capacity to recall previously experienced sensations, information, data and ideas.

  • brain m. — the ability of the brain to use knowledge gained from past experience. This is essential for the process of learning by animals. The process is poorly understood, but its practical application is sophisticated, especially in dogs.
  • m. cell — an expanded clone of small lymphocytes derived from stimulated antigen-sensitive B and T lymphocytes. They have antigen receptors of the same specificity as the parent cell. Important in the secondary immune response.
  • immunological m. — the ability of the immune system to respond to more strongly and rapidly to the second and subsequent exposures to an antigen.
  • suture m. — a property of some synthetic fibers which encourages the spontaneous untying of knots—the ‘memory’ of the fiber is that it is a straight fiber.


 
Word Tutor: memory
pronunciation

IN BRIEF: The act or power of remembering. Also: The part of a computer that stores information.

pronunciation We can invent only with memory. — Alphonse Karr (1808-1890)

Tutor's tip: The "memoir" (a biography or autobiography) of a person with a bad "memory" (the mental faculty of remembering) is often more fiction than fact -- and usually more entertaining!

 
Quotes About: Memory

Quotes:

"If you want to win friends, make it a point to remember them. If you remember my name, you pay me a subtle compliment; you indicate that I have made an impression on you. Remember my name and you add to my feeling of importance." - Dale Carnegie

"Memory is the mother of all wisdom." - Aeschylus

"This boy is dead now, I knew it before taking him in my arms, I can remember his face, his suffering, his voice." - Princess of Wales Diana

"If I could remember the names of all these particles, I'd be a botanist." - Enrico Fermi

"I always have trouble remembering three things: faces, names, and -- I can't remember what the third thing is." - Fred A. Allen

"People tend to remember my performances, not me." - Ellen Barkin

See more famous quotes about Memory

 
Wikipedia: memory


Neuropsychology


Topics

Brain-computer interfacesBrain damage
Brain regionsClinical neuropsychology
Cognitive neuroscienceHuman brain
NeuroanatomyNeurophysiology
PhrenologyPopular misconceptions

Brain functions

arousalattention
consciousnessdecision making
executive functionslanguage
learningmemory
motor coordinationperception
planningproblem solving
thought

People

Arthur L. BentonAntónio Damásio
Kenneth HeilmanPhineas Gage
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H.M.

Tests

Bender-Gestalt Test
Benton Visual Retention Test
Clinical Dementia Rating
Continuous Performance Task
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Lexical decision task
Mini-mental state examination
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Mind and Brain Portal

In psychology, memory is an organism's ability to store, retain, and subsequently retrieve information. Traditional studies of memory began in the realms of philosophy, including techniques of artificially enhancing the memory. The late nineteenth and early twentieth century put memory within the paradigms of cognitive psychology. In recent decades, it has become one of the principal pillars of a branch of science called cognitive neuroscience, a interdisciplinary link between cognitive psychology and neuroscience.

Processes

There are several ways to classify memories, based on duration, nature and retrieval of information. From an information processing perspective there are three main stages in the formation and retrieval of memory:

  • Encoding or registration (processing and combining of received information)
  • Storage (creation of a permanent record of the encoded information)
  • Retrieval or recall (calling back the stored information in response to some cue for use in a process or activity)

Classification

A basic and generally accepted classification of memory is based on the duration of memory retention, and identifies three distinct types of memory: sensory memory, short term memory and long term memory.

Sensory

Sensory memory corresponds approximately to the initial 200 - 500 milliseconds after an item is perceived. The ability to look at an item, and remember what it looked like with just a second of observation, or memorization, is an example of sensory memory. With very short presentations, participants often report that they seem to "see" more than they can actually report. The first experiments exploring this form of sensory memory were conducted by George Sperling using the "partial report paradigm." Subjects were presented with a grid of 12 letters, arranged into three rows of 4. After a brief presentation, subjects were then played either a high, medium or low tone, cuing them which of the rows to report. Based on these partial report experiments, Sperling was able to show that the capacity of sensory memory was approximately 12 items, but that it degraded very quickly (within a few hundred milliseconds). Because this form of memory degrades so quickly, participants would see the display, but be unable to report all of the items (12 in the "whole report" procedure) before they decayed. This type of memory cannot be prolonged via rehearsal.

Short-term

Some of the information in sensory memory is then transferred to short-term memory. Short-term memory allows one to recall something from several seconds to as long as a minute without rehearsal. Its capacity is also very limited: George A. Miller, when working at Bell Laboratories, conducted experiments showing that the store of short term memory was 7±2 items (the title of his famous paper, "The magic number 7±2"). Modern estimates of the capacity of short-term memory are lower, typically on the order of 4-5 items, and we know that memory capacity can be increased through a process called chunking. For example, if presented with the string:

FBIPHDTWAIBM

people are able to remember only a few items. However, if the same information is presented in the following way:

FBI PHD TWA IBM

people can remember a great deal more letters. This is because they are able to chunk the information into meaningful groups of letters. Beyond finding meaning in the acronyms above, Herbert Simon showed that the ideal size for chunking letters and numbers, meaningful or not, was three. This may be reflected in the tendency to remember phone numbers as several chunks of three numbers with the final four-number groups generally broken down into two groups of two.

Short-term memory is believed to rely mostly on an acoustic code for storing information, and to a lesser extent a visual code. Conrad (1964)[1] found that test subjects had more difficulty recalling collections of words that were acoustically similar (e.g. dog, fog, bog, log).

Long-term

The storage in sensory memory and short-term memory generally have a strictly limited capacity and duration, which means that information is available for a certain period of time, but is not retained indefinitely. By contrast, long-term memory can store much larger quantities of information for potentially unlimited duration (sometimes a whole life span). While short-term memory encodes information acoustically, long-term memory encodes it semantically. Baddeley (1966)[2] found that after 20 minutes, test subjects had the greatest difficulty recalling a collection of words that had similar meanings (e.g. big, large, great, huge).

Short-term memory is supported by transient patterns of neuronal communication, dependent on regions of the frontal lobe (especially dorsolateral prefrontal cortex) and the parietal lobe. Long-term memories, on the other hand, are maintained by more stable and permanent changes in neural connections widely spread throughout the brain. The hippocampus is essential to the consolidation of information from short-term to long-term memory, although it does not seem to store information itself. Rather, it may be involved in changing neural connections for a period of three months or more after the initial learning.

One of the main functions of sleep is thought to be to improve consolidation of information, as it can be shown that memory depends on getting sufficient sleep between training and test, and that the hippocampus replays activity from the current day while sleeping. For example, if we are given a random seven-digit number, we may remember it for only a few seconds and then forget, which means it was stored into our short-term memory. On the other hand, we can remember telephone numbers for many years through repetition; those long-lasting memories are said to be stored in our long-term memory.

Models

Models of memory provide abstract representations of how memory is believed to work. Below are several models proposed over the years by various psychologists.

Multi-store (Atkinson-Shiffrin memory model)

Multistore_model.png

The multi-store model (also known as Atkinson-Shiffrin memory model) was first described in 1968 by Atkinson and Shiffrin.

The multi-store model has been criticized for being too simplistic. For instance, long-term memory is believed to be actually made up of multiple subcomponents, such as episodic and procedural memory. It also proposes that rehearsal is the only mechanism by which information eventually reaches long-term storage, but evidence shows us capable of remembering things without rehearsal.

Working memory

The working memory model.
The working memory model.

In 1974 Baddeley and Hitch proposed a working memory model which replaced the concept of general short term memory with specific, active components. In this model, working memory consists of three basic stores: the central executive, the phonological loop and the visuo-spatial sketchpad. In 2000 this model was expanded with the multimodal episodic buffer.[3]

The central executive essentially acts as attention. It channels information to the three component processes: the phonological loop, the visuo-spatial sketchpad, and the episodic buffer.

The phonological loop stores auditory information by silently rehearsing sounds or words in a continuous loop; the articulatory process (the "inner voice") continuously "speaks" the words to the phonological store (the "inner ear"). The phonological loop has a very limited capacity, which is demonstrated by the fact that it is easier to remember a list of short words (e.g. dog, wish, love) than a list of long words (e.g. association, systematic, confabulate) because short words fit better in the loop. However, if the test subject is given a task that ties up the articulatory process (saying "the, the, the" over and over again), then a list of short words is no easier to remember.

The visuo-spatial sketchpad stores visual and spatial information. It is engaged when performing spatial tasks (such as judging distances) or visual ones (such as counting the windows on a house or imagining images).

The episodic buffer is dedicated to linking information across domains to form integrated units of visual, spatial, and verbal information and chronological ordering (e.g., the memory of a story or a movie scene). The episodic buffer is also assumed to have links to long-term memory and semantical meaning.

The working memory model explains many practical observations, such as why it is easier to do two different tasks (one verbal and one visual) than two similar tasks (eg two visual), and the aforementioned word-length effect. However, the concept of a central executive as noted here has been criticized as inadequate and vague.

Levels of processing

Craik and Lockhart (1972) proposed that it is the method and depth of processing that affects how an experience is stored in memory, rather than rehearsal.

  • Organization - Mandler (1967) gave participants a pack of word cards and asked them to sort them into any number of piles using any system of categorisation they liked. When they were later asked to recall as many of the words as they could, those who used more categories remembered more words. This study suggested that the act of organising information makes it more memorable.
  • Distinctiveness - Eysenck and Eysenck (1980) asked participants to say words in a distinctive way, e.g. spell the words out loud. Such participants recalled the words better than those who simply read them off a list.
  • Effort Tyler et al. (1979) had participants solve a series of anagrams, some easy (FAHTER) and some difficult (HREFAT). The participants recalled the difficult anagrams better, presumably because they put more effort into them.

Classification by information type

Long-term memory can be divided into declarative (explicit) and procedural (implicit) memories. (Anderson, 1976)

Declarative memory requires conscious recall, in that some conscious process must call back the information. It is sometimes called explicit memory, since it consists of information that is explicitly stored and retrieved.

Declarative memory can be further sub-divided into semantic memory, which concerns facts taken independent of context; and episodic memory, which concerns information specific to a particular context, such as a time and place. Semantic memory allows the encoding of abstract knowledge about the world, such as "Paris is the capital of France". Episodic memory, on the other hand, is used for more personal memories, such as the sensations, emotions, and personal associations of a particular place or time. Autobiographical memory - memory for particular events within one's own life - is generally viewed as either equivalent to, or a subset of, episodic memory. Visual memory is part of memory preserving some characteristics of our senses pertaining to visual experience. We are able to place in memory information that resembles objects, places, animals or people in sort of a mental image. Visual memory can result in priming and it is assumed some kind of perceptual representational system underlies this phenomenon. [1]

In contrast, procedural memory (or implicit memory) is not based on the conscious recall of information, but on implicit learning. Procedural memory is primarily employed in learning motor skills and should be considered a subset of implicit memory. It is revealed when we do better in a given task due only to repetition - no new explicit memories have been formed, but we are unconsciously accessing aspects of those previous experiences. Procedural memory involved in motor learning depends on the cerebellum and basal ganglia.

So far, nobody has successfully been able to isolate the time dependence of these suggested memory structures.

Classification by temporal direction

A further major way to distinguish different memory functions is whether the content to be remembered is in the past, retrospective memory, or whether the content is to be remembered in the future, prospective memory. Thus, retrospective memory as a category includes semantic memory and episodic/autobiographical memory. In contrast, prospective memory is memory for future intentions, or remembering to remember (Winograd, 1988). Prospective memory can be further broken down into event- and time-based prospective remembering. Time-based prospective memories are triggered by a time-cue, such as going to the doctor (action) at 4pm (cue). Event-based prospective memories are intentions triggered by cues, such as remembering to post a letter (action) after seeing a mailbox (cue). Cues do not need to be related to the action (as the mailbox example is), and lists, sticky-notes, knotted handkerchiefs, or string around the finger are all examples of cues that are produced by people as a strategy to enhance prospective memory.

Physiology

Overall, the mechanisms of memory are not completely understood. Brain areas such as the hippocampus, the amygdala, or the mammillary bodies are thought to be involved in specific types of memory. For example, the hippocampus is believed to be involved in spatial learning and declarative learning. Damage to certain areas in patients and animal models and subsequent memory deficits is a primary source of information. However, rather than implicating a specific area, it could be that damage to adjacent areas, or to a pathway traveling through the area is actually responsible for the observed deficit. Further, it is not sufficient to describe memory, and its counterpart, learning, as solely dependent on specific brain regions. Learning and memory are attributed to changes in neuronal synapses, thought to be mediated by long-term potentiation and long-term depression.

Disorders

Much of the current knowledge of memory has come from studying memory disorders. Loss of memory is known as amnesia. There are many sorts of amnesia, and by studying their different forms, it has become possible to observe apparent defects in individual sub-systems of the brain's memory systems, and thus hypothesize their function in the normally working brain. Other neurological disorders such as Alzheimer's disease can also affect memory and cognition.

While not a disorder, a common temporary failure of word retrieval from memory is the tip-of-the-tongue phenomenon.

Impaired memory can be a symptom of hypothyroidism.

Memorization

Memorization is a method of learning that allows an individual to recall information verbatim. Rote learning is the method most often used. Methods of memorising things have been the subject of much discussion over the years with some writers, such as Cosmos Rossellius using visual alphabets. The spacing effect shows that an individual is more likely to remember a list of items when rehearsal is spaced over an extended period of time. In contrast to this is cramming which is intensive memorization in a short period of time. Also relevant is the Zeigarnik effect which states that people remember uncompleted or interrupted tasks better than completed ones.

In March 2007 it was reported that German researchers found they could use odors to re-activate new memories in the brains of people while they slept and the volunteers remembered better later.[4]

Tony Noice, an actor, director, teacher and cognitive researcher, and his psychologist wife Helga, have spent years trying to understand how actors remember their lines. They've found that if anyone uses the techniques that actors use, those techniques will help to improve memory in general.[5]

At the Center for Cognitive Science at Ohio State University, researchers have found that memory accuracy of adults is hurt by the fact that they know more than children and tend to apply this knowledge when learning new information. The findings appeared in the August 2004 edition of the journal Psychological Science.

Improving memory

The best way to improve memory seems to be to increase the supply of oxygen to the brain, which may be accomplished with aerobic exercises; walking for three hours each week suffices, as does swimming or bicycle riding.[6]

Such aerobic exercises have helped elderly people switch between mental tasks, concentrate better, and improve short-term memory. Exercise increases the number of connections between neurons, which is responsible for improved memory.[citation needed]

The International Longevity Center [2] released in 2001 a report [3] which includes in pages 14-16 recommendations for keeping the mind in good functionality until advanced age. Some of the recommendations are to stay intellectually active through learning, training or reading, to keep physically active so to promote blood irrigation to the brain, to socialize, to reduce stress, to keep sleep time regular, to avoid depression or emotional instability and to observe good nutrition.

Cultural references