Using rehearsal, we can keep information in short-term memory for a much longer period

Abstract

Short-term memory (STM) refers to systems which provide retention of limited amounts of material for a limited time period (seconds). Most investigated systems include Phonological, Spatial, and Visual STM, while STM storage exists also in other domains, as the somatosensory system. STM includes storage and rehearsal components, with the latter providing maintenance of events in memory against short-term forgetting. Discrete brain regions support STM, with left hemisphere posterior parietal and premotor frontal networks being more involved in Phonological STM, and right hemisphere regions in spatial STM. STM contributes to learning of new information and aspects of speech comprehension and production.

Short-term Artificial Memories

Short-term or working memory within the AIS is where new information is transitionally stored in a temporary knowledge domain (Crowder and Carbone, 2011a) while it is processed into new knowledge. This follows the paradigm that information content has no value until it is thought about (Brillouin, 2004). Short-term memory is where most reasoning within the AIS happens. Short-term memory provides a major functionality called rehearsals, which allows the AIS to continually refresh or rehearse STMs while they are being processed and reasoned about, so that memories do not degrade until they can be sent on to long-term memory (LTM) and acted upon by the artificial consciousness processes within the AIS’s cognitive framework (Crowder and Carbone, 2011a).

Short-term memory is much smaller in relative space compared with LTM. Short-term memory should not necessarily be perceived as a physical location, as in the human brain, but rather as the rapid and continuous processing of information content relative to a specific AIS directive or current undertaking. One must remember that STM, which includes all external and internal sensory inputs, will trigger a rehearsal if the AIS discovers a relationship to a previously interred piece of information content in either STM or LTM. Figure 14.2 illustrates the STM lower ontology for the AIS.

Summary

Short-term memory is an ability of the mind that is both enabled and constrained by the function and structure of neural circuits and systems. Prefrontal cortex plays a vital role in establishing the sustained patterns of neural activity that represent information in short-term memory, and the functional organization of prefrontal cortex provides valuable information regarding the nature of those representations. However, short-term memory is not localized to the prefrontal cortex. Many of the psychological aspects of short-term memory, including capacity limits, effects of interference, and its relationship to attention and long-term memory, can be best understood by considering the properties of the multiple, interacting components of these circuits and systems.

Abstract

Short-term memory (STM) encompasses cognitive functions for the storage, maintenance, and mental manipulation of information that is no longer present in the sensory environment. Selective attention, on the other hand, relates to functions that modulate the processing of sensory events during encoding. We review evidence from a series of three tactile memory experiments using electroencephalography and discuss our observations in the context of research on tactile perceptual attention and visual STM. Striking similarities across the domains of STM and perception indicate that the central executive system for tactile STM relies on control mechanisms that accomplish attentional selection during somatosensory encoding. Our findings support the view that STM emerges when attention is directed to the representation of sensory signals stored in modality-specific brain areas.

Short-term and long-term memory

Short-term memory, such as remembering a new telephone number, is easily disrupted until it has been stored in long-term memory, a process called consolidation. After consolidation, it can remain permanently, although the ability to retrieve it from long-term store depends on factors such as how often it is retrieved. Only a small number of short-term memories are consolidated, and this depends on the level of arousal and attention, which will depend on the personal significance of the information.

Short- and long-term memory are separate processes, and items do not have to pass through short-term memory in order to reach long-term memory. This is shown in the few patients whose short-term memory is damaged but who can still consolidate memories into long-term memory.

Definition

Short-term memory (STM) refers to the active retention (for humans, the ‘keeping in mind’) of information when it is not accessible from the environment. Working memory can be thought of as ‘STM+,’ the ‘+’ referring to the ability to manipulate or otherwise transform this information, to protect it in the face of interference, and to use it in the service of such high-level behaviors as planning, reasoning, and problem solving. STM and working memory are of central importance to the study of high-level cognition because they are believed to be critical contributors to such essential cognitive functions and properties as language comprehension, learning, planning, reasoning, and general fluid intelligence.

1.02.3.2 Short-Term Storage

Short-term memory (or short-term storage; the two are often used interchangeably) refers to retention of information in a system after information has been categorized and reached consciousness. In fact, contents of short-term memory are sometimes equated with the information of which a person is consciously aware. Information can be continually processed in short-term storage (e.g., via rehearsal or subvocal repetition). If a person is distracted, information is rapidly lost from this store.

Many different techniques have been developed to study aspects of short-term memory, but all have in common that subjects are given relatively brief numbers of items (often digits or words) and are asked to recall or recognize them later (often after some brief interfering task). Another term used for short-term memory is primary memory, owing to a distinction introduced by William James (1890/1950) between primary and secondary memory (reintroduced to the field much later by Waugh and Norman, 1965). Primary memory is what can be held in mind at once, whereas secondary memory referred to all other kinds of long-term memory. The terms short-term memory and long-term memory seem to have become accepted today.

1.02.3.2 Short-Term Storage

Short-term memory (or short-term storage; the two are often used interchangeably) refers to retention of information in a system after information has been categorized and reached consciousness. In fact, contents of short-term memory are sometimes equated with the information of which a person is consciously aware. Information can be continually processed in short-term storage (e.g., via rehearsal or subvocal repetition). If a person is distracted, information is rapidly lost from this store.

Many different techniques have been developed to study aspects of short-term memory, but all have in common that subjects are given relatively brief numbers of items (often digits or words) and are asked to recall or recognize them later (often after some brief interfering task).

Another term used for short-term memory is primary memory, owing to a distinction introduced by William James (1890/1950) between primary and secondary memory (reintroduced to the field much later by Waugh and Norman, 1965). Primary memory is what can be held in mind at once, whereas secondary memory referred to all other kinds of long-term memory. The terms short-term memory and long-term memory seem to have become accepted today.

1 Definitions and Terminology

‘Short-term memory’ refers to memory over a short time interval, usually 30s or less. Another term for the same concept is ‘immediate memory.’ Both these terms have been distinguished from the related terms ‘short-term store’ and ‘primary memory,’ each of which refers to a hypothetical temporary memory system. However, the term ‘short-term memory’ has also been used by many authors to refer to the temporary memory system. Thus, here the term ‘short-term memory’ is used in both senses.

It is important to distinguish ‘short-term memory’ from the related concepts ‘working memory’ (see Working Memory, Psychology of) and ‘sensory memory’. Some authors have used the terms ‘short-term memory’ and ‘working memory’ as synonymous, and indeed the term ‘working memory’ has been gradually replacing the term ‘short-term memory’ in the literature (and some authors now refer to ‘short-term working memory’; see Estes 1999). However, ‘working memory’ was originally adopted to convey the idea that active processing as well as passive storage is involved in temporary memory. ‘Sensory memory’ refers to memory that is even shorter in duration than short-term memory. Further, sensory memory reflects the original sensation or perception of a stimulus and is specific to the modality in which the stimulus was presented, whereas information in short-term memory has been coded so that it is in a format different from that originally perceived.

Summary of short-term memory and working memory deficits and their role in language processing

Reduced STM span, as often observed in aphasia, has few consequences for language comprehension and production if the span deficit reflects difficulty maintaining phonological information. In contrast, a deficit in maintaining semantic information causes difficulties for both comprehension and production. Phonological STM is important, however, for learning new phonological information; similarly, semantic STM is important for learning new semantic information. There is controversy whether semantic STM deficits reflect a rapid loss of semantic information or a deficit in various EFs (such as an inhibition deficit). Deficits in more complex WM appear to affect the ability to carry out what have been termed postinterpretive aspects of sentence processing rather than more on-line interpretive aspects (Caplan & Waters, 1999).