Short-term memory (sometimes referred to as "primary memory In psychology, memory is an organism's ability to store, retain, and recall information. Traditional studies of memory began in the fields 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" or "active memory") refers to the capacity for holding a small amount of information Information, in its most restricted technical sense, is an ordered sequence of symbols. As a concept, however, information has many meanings. Moreover, the concept of information is closely related to notions of constraint, communication, control, form, instruction, knowledge, meaning, mental stimulus, pattern, perception, and representation in mind Mind is the aspect of intellect and consciousness experienced as combinations of thought, perception, memory, emotion, will and imagination, including all unconscious cognitive processes. The term is often used to refer, by implication, to the thought processes of reason. Mind manifests itself subjectively as a stream of consciousness in an active, readily available state for a short period of time. The duration of short-term memory (when rehearsal or active maintenance is prevented) is believed to be in the order of seconds. Estimates of short-term memory capacity limits vary from about 4 to about 9 items, depending upon the experimental design used to estimate capacity. A commonly-cited capacity is 7±2 "The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information" is one of the most highly cited papers in psychology. It was published in 1956 by the cognitive psychologist George A. Miller of Princeton University's Department of Psychology in Psychological Review elements. In contrast, long-term memory Long-term memory is memory that can last as little as a few days or as long as decades. It differs structurally and functionally from working memory or short-term memory, which ostensibly stores items for only around 18 seconds (Peterson and Peterson, 1959). Biologically, short-term memory is a temporary potentiation of neural connections that can indefinitely stores a seemingly unlimited amount of information.

Short-term memory should be distinguished from 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. Working memory tasks include the active monitoring or manipulation of information or behaviors. It is a theoretical construct within cognitive psychology and neuroscience. Theories which refers to structures and processes used for temporarily storing and manipulating information (see more details below).

Contents

Existence of a separate store

A classical model of memory developed in the 1960s assumed that all memories pass from a short-term to a long-term store after a small period of time. This model is referred to as the "modal model" and has been most famously detailed by Shiffrin.[1] The exact mechanisms by which this transfer takes place, whether all or only some memories are retained permanently, and indeed the existence of a genuine distinction between the two stores, remain controversial topics among experts.

One form of evidence, cited in favor of the separate existence of a short-term store comes from anterograde amnesia Anterograde amnesia is a loss of the ability to create memories after the event that caused the amnesia occurs, leading to a partial or complete inability to recall the past. Anterograde amnesia and retrograde amnesia, where memories created prior to the event are lost, can occur together in the same patient. To a large degree, anterograde amnesia, the inability to learn new facts and episodes. Patients with this form of amnesia, have intact ability to retain small amounts of information over short time scales (up to 30 seconds) but are dramatically impaired in their ability to form longer-term memories (a famous example is patient HM Henry Gustav Molaison , better known as HM or H.M., was a memory-impaired patient who was widely studied from the late 1950s until his death. His case played a very important role in the development of theories that explain the link between brain function and memory, and in the development of cognitive neuropsychology, a branch of psychology that). This is interpreted as showing that the short-term store is spared from amnesia.

Other evidence comes from experimental studies showing that some manipulations (e.g., a distractor task, such as repeatedly subtracting a single-digit number from a larger number following learning) impair memory for the 3 to 5 most recently learned words of a list (presumably still held in short-term memory), while leaving recall for words from earlier in the list (presumably stored in long-term memory) unaffected; other manipulations (e.g., semantic similarity of the words) affect only memory for earlier list words,[2] but do not affect memory for the last few words in a list. These results show that different factors affect short term recall (disruption of rehearsal) and long-term recall (semantic similarity). Together, these findings show that long-term memory and short-term memory can vary independently of each other.

Not all researchers agree that short-term and long-term memory are separate systems. Some theorists propose that memory is unitary over all time scales, from milliseconds to years[3]. Support for the unitary memory hypothesis comes from the fact that it has been difficult to demarcate a clear boundary between short-term and long-term memory. For instance, Tarnow shows that the recall probability vs. latency curve is a straight line from 6 to 600 seconds, with the probability of failure to recall only saturating after 600 seconds [4]. If there were really two different memory stores operating in this time frame, one could expect a discontinuity in this curve. Other research has shown that the detailed pattern of recall errors looks remarkably similar for recall of a list immediately after learning (presumably from short-term memory) and recall after 24 hours (necessarily from long-term memory).[5]

Biological basis

It is proposed that short term memory is prolonged firing of neurons which depletes the Readily Releasable Pool (RRP) of neurotransmitter vesicles at presynaptic terminals[6]. The pattern of depleted presynaptic terminals represents the long term memory trace and the depletion itself is the short term memory. After the firing has slowed down, endocytosis Endocytosis is the process by which cells absorb molecules from outside the cell by engulfing them with their cell membrane. It is used by all cells of the body because most substances important to them are large polar molecules that cannot pass through the hydrophobic plasma or cell membrane. The process opposite to endocytosis is exocytosis causes short term memory to decay. If the endocytosis is allowed to finish (the memory is not activated again), the pattern of exhausted postsynaptic terminals becomes invisible and the short term memory disappears. The long term memory remains as the metastable pattern of the neuronal excitations.

Relationship with working memory

The relationship between short-term memory and 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. Working memory tasks include the active monitoring or manipulation of information or behaviors. It is a theoretical construct within cognitive psychology and neuroscience. Theories is described differently by various theories, but it is generally acknowledged that the two concepts are distinct. Working memory is a theoretical framework that refers to structures and processes used for temporarily storing and manipulating information. As such, working memory might also be referred to as working attention. Short-term memory generally refers, in a theory-neutral manner, to the short-term storage of information, and it does not entail the manipulation or organization of material held in memory. Thus while there are short-term memory components to working memory models, the concept of short-term memory is distinct from these more hypothetical concepts. Within Baddeley Alan Baddeley FRS, CBE is professor of psychology at the University of York. He is known for his work on working memory, in particular for his multiple components model's influential 1986 model of working memory there are two short-term storage mechanisms: the phonological loop and the visuospatial sketchpad. Most of the research referred to here involves the phonological loop, because most of the work done on short-term memory has used verbal material. In recent years, however, there has been a surge in research on visual short term memory[7], and also increasing work on spatial short term memory.[8]

Duration of short-term memory

The limited duration of short-term memory immediately suggests that its contents spontaneously decay over time. The decay assumption is part of many theories of short-term memory, most notably Baddeley's model of working memory. The decay assumption is usually paired with the idea of rapid covert rehearsal: In order to overcome the limitation of short-term memory, and retain information for longer, information must be periodically repeated, or rehearsed — either by articulating it out loud, or by mentally simulating such articulation. In this way, the information will re-enter the short-term store and be retained for a further period.

Several researchers, however, dispute that spontaneous decay plays any significant role in forgetting over the short term [9][10], and the evidence is far from conclusive[11].

Authors doubting that decay causes forgetting from short-term memory often offer as an alternative some form of interference: When several elements (such as digits, words, or pictures) are held in short term memory simultaneously, their representations compete with each other for recall, or degrade each other. Thereby, new content gradually pushes out older content, unless the older content is actively protected against interference by rehearsal or by directing attention to it[12].

Capacity of short-term memory

Whatever the cause or causes of forgetting over the short term may be, there is consensus that it severely limits the amount of new information that we can retain over brief periods of time. This limit is referred to as the finite capacity of short-term memory. The capacity of short-term memory is often called memory span, in reference to a common procedure of measuring it. In a memory span test, the experimenter presents lists of items (e.g. digits or words) of increasing length. An individual's span is determined as the longest list length that he or she can recall correctly in the given order on at least half of all trials.

In an early and highly influential article, The Magical Number Seven, Plus or Minus Two "The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information" is one of the most highly cited papers in psychology. It was published in 1956 by the cognitive psychologist George A. Miller of Princeton University's Department of Psychology in Psychological Review,[13] the psychologist George Miller George Armitage Miller is the author of one of the most highly cited papers in psychology, "The Magical Number Seven, Plus or Minus Two" published in 1956 in Psychological Review. This paper suggests that seven (plus or minus two) is the magic number that characterizes people's memory performance on random lists of letters, words, suggested that human short-term memory has a forward memory span of approximately seven items plus or minus two. More recent research has shown that this "magical number seven" is roughly accurate for college students recalling lists of digits, but memory span varies widely with populations tested and with material used. For example, the ability to recall words in order depends on a number of characteristics of these words: fewer words can be recalled when the words have longer spoken duration; this is known as the word-length effect,[14] or when their speech sounds are similar to each other; this is called the phonological similarity effect.[15] More words can be recalled when the words are highly familiar or occur frequently in the language.[16] Recall performance is also better when all of the words in a list are taken from a single semantic category (such as sports) than when the words are taken from different categories.[17] According to the available evidence, the best overall estimate of short-term memory is about four pieces or "chunks" of information.[18]

Chunking

Chunking is the process with which we can expand our ability to remember things in the short term. Chunking is also a process by which a person organizes material into meaningful groups. Although the average person may only retain about four different units in short-term memory, chunking can greatly increase a person's recall capacity. For example, in recalling a phone number, the person could chunk the digits into three groups: first, the area code (such as 215), then a three-digit chunk (123) and lastly a four-digit chunk (4567). This method of remembering phone numbers is far more effective than attempting to remember a string of 10 digits.

Practice and the usage of existing information in long-term memory can lead to additional improvements in one's ability to use chunking. In one testing session, an American cross-country runner was able to recall a string of 79 digits after hearing them only once by chunking them into different running times (e.g. the first four numbers were 1518, a three-mile time.)[19]

Factors Affecting Short Term Memory

It is very difficult to demonstrate the exact capacity of STM due to the fact that it will vary depending on the nature of the material to be recalled. Until now, there is no way of defining the basic unit of information to be stored in the STM store. It is also possible that STM is not the store described by Atkinson and Shiffrin. In that case, the task of defining the task of STM becomes even more difficult.

Some other factors are listed below: Reading Aloud: Digital spans tend to increase if the digits are read aloud by participants instead of being read sub-vocally. Baddley (1999) suggests that the sounds are also stored in the echoic store which makes storing it easier.

See also

References

Notes

  1. ^ Atkinson and Shiffrin, 1968
  2. ^ Davelaar, E. J., Goshen-Gottstein, Y., A., A., Haarmann, H. J., & Usher, M. (2005): The demise of short-term memory revisited: empirical and computational investigation of recency effects. Psychological Review, 112, pp. 3–42.
  3. ^ Brown, G. D. A., Neath, I., & Chater, N. (2007). A ratio model of scale-invariant memory and identification. Psychological Review, 114, 539-576.
  4. ^ Tarnow, 2007
  5. ^ Nairne, J. S., & Dutta, A. (1992). Spatial and temporal uncertainty in long-term memory. Journal of Memory and Language, 31, 396-407.
  6. ^ Tarnow, Eugen (2008): Short Term Memory May Be the Depletion of the Readily Releasable Pool of Presynaptic Neurotransmitter Vesicles. ([1])
  7. ^ Luck, S. J., & Vogel, E. K. (1997). The capacity of visual working memory for features and conjunctions. Nature, 390, 279-281.
  8. ^ Parmentier, F. B. R., Elford, G., & Maybery, M. (2005). Transitional information in spatial serial memory: path characteristics affect recall performance. Journal of Experimental Psychology: Learning, Memory, and Cognition, 31, 412-427.
  9. ^ Lewandowsky, S., Duncan, M., & Brown, G. D. A. (2004). Time does not cause forgetting in short-term serial recall. Psychonomic Bulletin & Review, 11, 771-790.
  10. ^ Nairne, J. S. (2002). Remembering over the short-term: The case against the standard model. Annual Review of Psychology, 53, 53-81.
  11. ^ Jonides, J., Lewis, R. L., Nee, D. E., Lustig, C. A., Berman, M. G., & Moore, K. S. (2008). The mind and brain of short-term memory. Annual Review of Psychology, 59, 193-224.
  12. ^ Oberauer, K., & Kliegl, R. (2006). A formal model of capacity limits in working memory. Journal of Memory and Language, 55, 601-626.
  13. ^ Miller, G. A. (1956). The magical number seven, plus or minus two: Some limits on our capacity for processing information. Psychological Review, 63, 81-97.
  14. ^ Baddeley, Thomson & Buchanan, 1975
  15. ^ Conrad & Hull, 1964
  16. ^ Poirier & Saint-Aubin, 1996
  17. ^ Poirier & Saint-Aubin, 1995
  18. ^ Cowan, N. (2001). The magical number 4 in short-term memory: A reconsideration of mental storage capacity. Behavioral and Brain Sciences, 24, 97-185.
  19. ^ Ericsson, Chase & Faloon, 1980

Bibliography

External links

Memory In psychology, memory is an organism's ability to store, retain, and recall information. Traditional studies of memory began in the fields 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
Basic concepts

Encoding In the study of memory, encoding is the processing of physical sensory input into one's memory. It is considered the first of three steps in memory information processing; the remaining two steps are storage and retrieval. During memory encoding, information may be processed about space, time, and frequency through automatic processing or • Storage The human memory has three processes: encoding , storage (throughput) and retrieval(output). Storage is the process of retaining information whether in the sensory memory, the short-term memory or the more permanent long-term memory • Recall When discussing memory, recall is the act of retrieving from long term memory a specific incident, fact or other item. A temporary failure to retrieve information from memory is known as the tip of the tongue phenomenon. Various means, including metacognitive strategies, priming, and measures of retention may be employed to improve later recall of

Attention Attention is the cognitive process of selectively concentrating on one aspect of the environment while ignoring other things. Attention has also been referred to as the allocation of processing resources • Memory consolidation Memory Consolidation is a category of processes that stabilize a memory trace after the initial acquisition. Consolidation is distinguished into two specific processes, Synaptic Consolidation, which occurs within the first few hours after learning and System Consolidation, where hippocampus-dependent memories become independent of the hippocampus • Neuroanatomy of memory The hippocampus is a structure in the brain that has been associated with various memory functions. It is part of the limbic system, and lies next to the medial temporal lobe. It is made up of two structures, the Ammon’s Horn, and the Dentate gyrus, each containing different types of cells
Long-term memory Long-term memory is memory that can last as little as a few days or as long as decades. It differs structurally and functionally from working memory or short-term memory, which ostensibly stores items for only around 18 seconds (Peterson and Peterson, 1959). Biologically, short-term memory is a temporary potentiation of neural connections that can Active recall Active recall is a principle of efficient learning, which claims the need to actively stimulate memory during the learning process. It contrasts with passive review, in which the learning material is processed passively • Autobiographical memory An autobiographical memory is a personal representation of general or specific events and personal facts. Autobiographical memory also refers to memory of a person’s history. An individual does not remember exactly everything that has happened in one’s past. Memory is constructive, where previous experience affects how we remember events and • Declarative memory Declarative memory is one of two types of long term human memory. It refers to memories which can be consciously recalled such as facts and events. Its counterpart is known as non-declarative or Procedural memory, which refers to unconscious memories such as skills (e.g. learning to ride a bicycle). Declarative memory can be divided into two • Episodic memory Episodic memory is the memory of autobiographical events that can be explicitly stated. Semantic and episodic memory together make up the category of declarative memory, which is one of the two major divisions in memory. The counterpart to declarative, or explicit memory, is procedural memory, or implicit memory • Explicit memory Explicit memory involves conscious recollection, compared with implicit memory which is an unconscious, nonintentional form of memory. Remembering a specific driving lesson is an example of explicit memory, while improving your driving skills during the lesson is an example of implicit memory • Flashbulb memory A flashbulb memory is a memory created in great detail during a personally significant event. These memories are perceived to have a "photographic" quality. The term was coined by Brown and Kulik, who found highly emotional memories were often vividly recalled, even some time after the event. For example, a great many people in the U.S • Hyperthymesia Hyperthymesia also known as piking or hyperthymestic syndrome is a condition where the affected individual has a superior autobiographical memory. "Thymesia" comes from the Greek word θύμησις, thymesis meaning "memory". As first described in the Neurocase article "A case of unusual autobiographical remembering," • Implicit memory 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. Evidence for implicit memory arises in priming, a process whereby subjects show improved performance on tasks for which they have been subconsciously prepared. Implicit memory also leads to • Procedural memory Procedural memory is our memory for how to do things. When needed, procedural memories are automatically retrieved and utilized for the execution of the step-by-step procedures involved in both cognitive and motor skills; from tying your shoes to flying an airplane. This process occurs without the need for conscious control or attention • Rote learning Rote learning is a learning technique which avoids understanding of a subject and instead focuses on memorization. The major practice involved in rote learning is learning by repetition. The idea is that one will be able to quickly recall the meaning of the material the more one repeats it • Selective retention • 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. Semantic and episodic memory together make up the • Tip of the tongue The tip of the tongue phenomenon is an instance of knowing something that cannot immediately be recalled. TOT is an experience with memory recollection involving difficulty retrieving a well-known word or familiar name. When experiencing TOT, people feel that the blocked word is on the verge of being recovered. Despite failure in finding the word,
Short-term memory The Magical Number Seven, Plus or Minus Two "The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information" is one of the most highly cited papers in psychology. It was published in 1956 by the cognitive psychologist George A. Miller of Princeton University's Department of Psychology in Psychological Review • 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. Working memory tasks include the active monitoring or manipulation of information or behaviors. It is a theoretical construct within cognitive psychology and neuroscience. Theories
Sensory memory Sensory memory is the ability to retain impressions of sensory information after the original stimulus has ceased. It refers to items detected by the sensory receptors which are retained temporarily in the sensory registers and which have a large capacity for unprocessed information but are only able to hold accurate images of sensory information Echoic memory Echoic Memory, the audit version of sensory memory, refers to the phenomenon in which there is a brief mental echo that continues to sound after auditory stimuli has been heard. In comparison to sensory and iconic memory, echoic memory is thought to last a little longer, for upwards of about three or four seconds. Due to its short span, echoic • Iconic memory Iconic memory is a type of short term visual memory , named by George Sperling in 1960. Experiments performed by Sperling and colleagues provided evidence for a rapidly decaying sensory trace, lasting only approximately 250 ms after the offset of a display • Motor learning Motor learning is the process of improving the motor skills, the smoothness and accuracy of movements. It is obviously necessary for complicated movements such as speaking, playing the piano, climbing trees and eating bananas but it is also important for calibrating simple movements like reflexes, as parameters of the body and environment change • Visual memory Visual memory is a 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. Some authors refer to this experience as an “our mind's eye” through which we can retrieve from our memory a
Forgetting Amnesia Amnesia is a condition in which memory is disturbed or lost. Memory in this context refers either to stored memories or to the process of committing something to memory. The causes of amnesia have traditionally been divided into the "organic" or the "functional". Organic causes include damage to the brain, through physical • Anterograde amnesia Anterograde amnesia is a loss of the ability to create memories after the event that caused the amnesia occurs, leading to a partial or complete inability to recall the past. Anterograde amnesia and retrograde amnesia, where memories created prior to the event are lost, can occur together in the same patient. To a large degree, anterograde amnesia • Childhood amnesia • Forgetting curve • Memory inhibition • Post-traumatic amnesia • Psychogenic amnesia • Repressed memory • Retrograde amnesia • Selective memory loss • Transient global amnesia • Weapon focus
Research Art of memory • Exceptional memory • Indirect tests of memory • Lost in the mall technique • Memory disorder • Reconstruction of automobile destruction • The Seven Sins of Memory
Related concepts Absent-mindedness • Atkinson-Shiffrin memory model • Confabulation • Cryptomnesia • Emotion and memory • Eidetic memory • Exosomatic memory • Free recall • Involuntary memory • Levels-of-processing effect • List of memory biases • Memory and aging • Memory and trauma • Metamemory • Mnemonic • Prospective memory • Priming • Recovered memory therapy • Retrospective memory
Culture and society Cultural memory • False memory syndrome • Politics of memory • Shass Pollak • Transactive memory • World Memory Championships
Notable people Robert A. Bjork • Stephen J. Ceci • Susan Clancy • Dominic O'Brien • Hermann Ebbinghaus • Sigmund Freud • Jennifer Freyd • Patricia Goldman-Rakic • Jonathan Hancock • HM (patient) • Ivan Izquierdo • Judith Lewis Herman • Eric Kandel • KC (patient) • Elizabeth Loftus • Geoffrey Loftus • Marcia K. Johnson • James McGaugh • Paul R. McHugh • George Armitage Miller • Lynn Nadel • Ben Pridmore • Henry L. Roediger III • Steven Rose • Cosmos Rossellius • Daniel Schacter • Richard Shiffrin • Larry Squire • Susumu Tonegawa • Anne Treisman • Endel Tulving

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