A neural system analysis of memory storage and retrieval.

Contends that from an information-processing viewpoint, memory can be subdivided into cue-access, short-term memory, and long-term memory storage and retrieval systems, which in turn are controlled by a number of operations, (e.g., match-mismatch, decay, and selective attention). Furthermore, it is assumed that specific neural substrates are maximally involved in the modulation of these specific processes essential to efficient mnemonic processing of information. Evidence is presented from previous studies to support this theoretical view of information processing. This evidence suggests that (a) the sensory systems and the cerebral cortex are critically involved in match-mismatch processing of information in the cue-access system, (b) the midbrain reticular formation and association cortex process information in the short-term memory system, and (c) the hippocampus is critically involved in consolidation and read-out of information in the long-term memory system. Evidence is also presented to suggest that after an initial preperceptual analysis information is transferred in parallel to the short-term and long-term memory systems, but that superimposed upon this parallel structure are sequential transfer processes (e.g., rehearsal). (6 p. ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term working memory.

To account for the large demands on working memory during text comprehension and expert performance, the traditional models of working memory involving temporary storage must be extended to include working memory based on storage in long-term memory. In the proposed theoretical framework cognitive processes are viewed as a sequence of stable states representing end products of processing. In skilled activities, acquired memory skills allow these end products to be stored in long-term memory and kept directly accessible by means of retrieval cues in short-term memory, as proposed by skilled memory theory. These theoretical claims are supported by a review of evidence on memory in text comprehension and expert performance in such domains as mental calculation, medical diagnosis, and chess. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory skill.

Argues that acquired memory skills best account for individual differences in memory performance. W. G. Chase and K. A. Ericsson's (1982) theory that improved memory or memory skills are due to the acquisition of more efficient storage and retrieval processes using long-term memory (LTM) is presented. This theory specifies 3 principles that characterize the structure of memory skills: (1) Information rapidly stored in LTM is encoded in terms of knowledge structures in semantic memory (meaningful encoding); (2) during storage in LTM, special retrieval cues are explicitly associated with the memory encoding of the presented information (retrieval structure); and (3) encoding and retrieval operations using LTM can be dramatically sped up by practice, making the rate of information storage in LTM comparable to that of short-term memory. Empirical evidence of the exceptional performance of a large number of memory experts is examined in the light of these principles. It is contended that strong evidence for these principles has also been found for normal Ss, when they are given more than a couple of hours of practice or training on memory tasks. It is concluded that expert memory skill is related to normal Ss' superior memory for meaningful information. (French abstract) (4? p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The retrieval of attention-dependent long-term memory traces

Phenomenon of memory dissociation is proposed as a paradigm for studying the retrieval processes of the long-term memory. The memory-dissociated states of brain are produced by external influence and result in selective reversible disturbances of the retrieval processes without substantial changes in perception and storage of new information. Analysis of dissociated states induced by pharmacological influences has led us to the following conclusions: 1) the reversible failures of the retrieval processes are usual for the attention-dependent form of long-term memory, 2) hippocampus is the key structure in brain mechanisms that realize the engram selection during memory retrieval, 3) the central cholinergic and GABAergic systems regulate the retrieval of information, 4) steady disturbances of retrieval of the long-term attention-dependent memory are accompanied by strongly pronounced changes in hippocampal cells including those at the membrane and genomic levels.     

Evolving conceptions of memory storage, selective attention, and their mutual constraints within the human information-processing system.

The purpose of this review is to formulate a revised model of information processing that takes into account recent research on memory storage, selective attention, effortful versus automatic processing, and the mutual constraints that these areas place on one another. One distinctive aspect of the proposed model is the inclusion of two phases of sensory storage in each modality. The first phase extends sensation of several hundred milliseconds, whereas the second phase is a vivid recollection of sensation. The mechanism of at least the longer phase is the activation of features in long-term memory, comparable to the mechanism of non-sensory, short-term storage. Another distinctive aspect of the model is that habituation/dishabituation and central executive processes together are assumed to determine the focus of attention, without the need for either an early or a late attentional filter. Research issues that contribute to a comparison of models is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory and individual differences in comprehension and memory of text.

Attempted to determine whether working memory processes measured by the Reading Span Test would be strongly associated with the ability to integrate information from different parts of a passage to infer an idea not explicitly stated in the passage. The study also assessed the influence of working memory processes on ability to encode explicitly stated and inferred information into long-term memory. 29 undergraduates were administered a letter span test and a reading span test. The ability to store and process information in working memory was shown to be positively related to (a) scores on a standardized reading comprehension test, (b) long-term memory encoding and retrieval of explicitly stated text information, and (c) integration of text information for the purpose of drawing inferences. Variations in only the storage capacity of working memory were not related to these measures. It is concluded that the ability to coordinate storage and process functions in working memory may be an important determinant of text processing skill, especially with respect to encoding information into long-term memory. (12 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of levels of processing on recall from working memory and delayed recall tasks.

Recent research in working memory has highlighted the similarities involved in retrieval from complex span tasks and episodic memory tasks, suggesting that these tasks are influenced by similar memory processes. In the present article, the authors manipulated the level of processing engaged when studying to-be-remembered words during a reading span task (Experiment 1) and an operation span task (Experiment 2) in order to assess the role of retrieval from secondary memory during complex span tasks. Immediate recall from both span tasks was greater for items studied under deep processing instructions compared with items studied under shallow processing instructions regardless of trial length. Recall was better for deep than for shallow levels of processing on delayed recall tests as well. These data are consistent with the primary-secondary memory framework, which suggests that to-be-remembered items are displaced from primary memory (i.e., the focus of attention) during the processing phases of complex span tasks and therefore must be retrieved from secondary memory. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Predicting syndromes of amnesia from a composite holographic associative recall/recognition model (CHARM)

The composite holographic associative recall/recognition model (CHARM) is used to predict the amnesia syndromes that are expected under conditions of discrete lesions to different components of the model. The components that are needed to allow recognition, recall, and rehearsal are: (1) perceptual/lexical processing and pattern identification, (2) consciousness or working memory, (3) association formation, (4) composite storage, (5) novelty monitoring and control, and (6) retrieval. Deficits in each of these components will have specific effects on memory, generating characteristic profiles of performance. Comparison of the profiles exhibited by patients to the component-based profiles predicted by the model identify the component impaired in a given patient, and connect the memory impairments to the underlying infarcted brain structures. The model, thus, relates the memory tasks to the particular memory components that allow enactment of those tasks, and shows how the dysfunction of particular components produces specific impairments.     

Short- and long-term memory retrieval: A comparison of the effects of information load and relatedness.

The separate applications of the Sternberg and fact-retrieval paradigms promote a view that short- and long-term memory are functionally distinct. However, effects of information load and relatedness, observed in both paradigms, support a more unified approach to memory retrieval. The two experiments of this article allow for direct comparison of these effects as observed in a fact-retrieval task, a Sternberg task, and a hybrid precuing task. These experiments are motivated by an associative approach in which performance in all tasks is seen to depend upon a parallel search driven by spreading activation. Decision-time data are explained in an indirect-pathway model with two important features: (a) Pretrial activation levels of areas in memory can vary to reflect differences between short-term and long-term retrieval; and (b) for related material, decisions can be based upon indirect pathways that connect the elements of a test probe through preexperimental associations in memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychobiology of active and inactive memory.

Presents a brief history and review of the short-term and long-term memory distinction and concludes that this distinction is no longer adequate for either human or animal memory data. Simple memories for events are apparently formed quickly and are permanent. In such cases, an initial physiologically unstable period is not required. Thus, most forgetting is the result of a retrieval failure rather than a storage failure. A distinction between active memory (AM) and inactive memory (IM) is made. AM is a subset of IM and contains either newly formed memories or established retrieved memories or both. Implications for psychobiology of the AM and IM distinction are discussed. It is suggested, for example, that while in AM, memories are particularly open to disruption either by amnesic agents or through other forms of interference. The forgetting process for new and established memories is time dependent (but independent of memory age) and is based on interference. It is desirable to maintain the distinction between memory storage and memory retrieval even while recognizing that associative storage aids in retrieval. The search for the biological basis of rapidly forming memories, perhaps based on the restructuring of protein fragments, remains important, but the physiological brain processes underlying memory interference and retrieval require greater emphasis. (5? p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sequential effects in lexical decision: Tests of compound-cue retrieval theory.

According to compound-cue retrieval theories, responses in lexical decision are determined by a passive process that matches a compound of the items in short-term memory against all of the information in long-term memory. Because responses depend on other items in short-term memory in addition to the target item about which a lexical decision is required, compound-cue theories must predict sequential effects and priming effects. For example, a nonword preceding a target should slow responses to the target, and a prime word related to a target word can affect responses to the target even when another item intervenes between them. In this article, the results of 4 experiments are presented and sequential effects are shown to be in accord with compound-cue theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synergistic ecphory in recall and recognition.

Describes a general model of retrieval of episodic memory information, within which basic phenomena of recall and recognition can be integrated and related to commonly accepted theoretical ideas. The model also provides a statement of the relation between recall and recognition as 2 forms of retrieval: They are similar with respect to the process of ecphory, combining trace information and retrieval information into ecphoric information; they are different with respect to conversion of ecphoric information into recollective experience and memory performance. (French abstract) (52 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Human problem solving: The state of the theory in 1970.

Summarizes research of the past 15 yr. directed toward discovering and explicating the organization of information processes that underlies human problem solving. The basic characteristics of the human information processing system (IPS) serial processing, small short-term memory, infinite long-term memory with fast retrieval but slow storage impose strong conditions on the ways in which the system can seek solutions to problems in large problem spaces. The current theory is described in 4 broad propositions: (a) a few gross characteristics of the human IPS are invariant over task and problem solver; (b) these characteristics determine that a task environment is represented (in the IPS) as a problem space, and that problem solving takes place in a problem space; (c) the structure of the task environment determines the possible structures of the problem space; and (d) the structure of the problem space determines the possible programs that can be used for problem solving. These propositions and their relation to the known characteristics of the IPS are developed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal dynamics of brain activation during a working memory task

Working memory is responsible for the short-term storage and online manipulation of information necessary for higher cognitive functions, such as language, planning and problem-solving. Traditionally, working memory has been divided into two types of processes: executive control (governing the encoding manipulation and retrieval of information in working memory) and active maintenance (keeping information available 'online'). It has also been proposed that these two types of processes may be subserved by distinct cortical structures, with the prefrontal cortex housing the executive control processes, and more posterior regions housing the content-specific buffers (for example verbal versus visuospatial) responsible for active maintenance. However, studies in non-human primates suggest that dorsolateral regions of the prefrontal cortex may also be involved in active maintenance. We have used functional magnetic resonance imaging to examine brain activation in human subjects during performance of a working memory task. We used the temporal resolution of this technique to examine the dynamics of regional activation, and to show that prefrontal cortex along with parietal cortex appears to play a role in active maintenance.     

Interpreting the influence of implicitly activated memories on recall and recognition.

A model concerning the influence of implicitly activated information on cued recall and recognition is presented. The model assumes that studying a familiar word activates its associates and creates an implicit representation in long-term working memory. Test cues also activate their associates, with memory performance determined by a sampling process that operates on the intersection of information activated by the test cue with information previously activated by the studied word. Successful sampling is enhanced by preexisting connections among the associates of the studied word and by preexisting connections between it and the retrieval cue. However, the usefulness of the implicit representation is reduced by the activation of competing associates and by shifts of attention before testing. Experiments designed to test predictions of the model indicate that the associates of a familiar word can exert a powerful effect on its cued recall and recognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Origin and evolution of sleep: roles of vision and endothermy

The origin of both sleep and memory appears to be closely associated with the evolution of mechanisms of enhancement and maintenance of synaptic efficacy. After the origin of activity-dependent synaptic plasticity, whereby single activations of synapses led to short-term efficacy enhancements, lengthy maintenance of the enhancements probably was achieved by repetitive activations ("dynamic stabilization"). These are thought to have occurred either in the course of frequent functional use, or to have been induced spontaneously within the brain to maintain synaptic efficacies in circuits that were in infrequent use. The latter repetitive activations are referred to as 'non-utilitarian' dynamic stabilization. With the evolution of increasing repertories and complexities of behavioral and sensory capabilities-with vision usually being the vastly preeminent sense-brain complexity increased markedly. Accompanying the greater complexity, needs for storage and maintenance of hereditary and experimental information (memories) also increased greatly. It is suggested that these increases led to conflicts between sensory input processing during restful waking and concomitant 'non-utilitarian' dynamic stabilization of infrequently used memory circuits. The selective pressure for the origin of primitive sleep may have been a need to achieve greater depression of central processing of sensory inputs-largely complex visual information-than occurs during restful waking. The electrical activities of the brain during sleep (aside from those that subserve autonomic activities) may function largely to maintain sleep and to dynamically stabilize infrequently used circuitry encoding memories. Sleep may not have been the only evolutionary adaptation to conflicts between dynamic stabilization and sensory input processing. In some ectothermic vertebrates, sleep may have been postponed or rendered unnecessary by a more readily effected means of resolution of the conflicts, namely, extensive retinal processing of visual information during restful waking. By this means, processing of visual information in central regions of the brain may have been maintained at a sufficiently low level to allow adequate concomitant dynamic stabilization. As endothermy evolved, the skeletal muscle hypotonia of primitive sleep may have become insufficient to prevent sleep-disrupting skeletal muscle contractions during 'non-utilitarian' dynamic stabilization of motor circuitry at the accompanying higher body temperatures and metabolic rates. Selection against such disruption during dynamic stabilization of motor circuitry may have led to the inhibition of skeletal muscle tone during a portion of primitive sleep, the portion designated as "rapid-eye-movement sleep." Many marine mammals that are active almost continuously engage only in unihemispheric non-rapid-eye-movement sleep. They apparently do not require rapid-eye-movement sleep and accompanying 'non-utilitarian' dynamic stabilization of motor circuitry because this circuitry is in virtually continuous use. Studies of hibernation by arctic ground squirrels suggest that each hour of sleep stabilizes brain synapses for as long as four hours.     

Word-frequency effects on short-term memory tasks: evidence for a redintegration process in immediate serial recall

Four experiments investigated the mechanisms responsible for the advantage enjoyed by high-frequency words in short-term memory tasks. Experiment 1 demonstrated effects of word frequency on memory span that were independent of differences in speech rate. Experiments 2 and 3 showed that word frequency has an increasing effect on serial recall across serial positions, but Experiment 4 showed that this effect was abolished for backward recall. A model that includes a redintegration process that operates to "clean up" decayed short-term memory traces is proposed, and the multinomial processing tree model described by R. Schweickert (1993) is used to provide a quantitative fit to data from Experiments 2, 3, and 4.     

Effects of serial rehearsal training on memory search.

Examined the effects of storage processing on short-term memory search. 32 moderate and 32 high IQ 4th-5th graders were given an S. Sternberg (1966, 1969) recognition memory task. Half of the Ss were trained to use a serial rehearsal strategy during target set storage, and half were given no specific strategy training. The training variable was crossed with rehearsal requirement (overt or covert) so that storage processing could be monitored directly. Dependent measures included S-paced study times, overt rehearsals, and reaction times. Results indicate IQ-related differences in the rate of memory search in the absence of differences in rehearsal during storage. In addition, serial rehearsal training facilitated memory search when rehearsal was covert, particularly for high IQ Ss. The data are discussed with regard to target set storage resulting from a serial rehearsal pattern and to the apparent inverse relationship between IQ and memory-search rate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of mood and severity on memory processes in depression and mania.

This article examines the relation between mood state, severity of psychopathology, and memory in the affective disorders by reviewing the literature concerned with memory processes in depression and mania. On the basis of this review, a model is presented that tries to reconcile the varied findings encountered in the literature. Specifically, this model proposes that memory processes in these disorders result from the operation of two diagnostically nonspecific mechanisms, mood state and severity of psychopathology. Mood state is thought to affect memory in two related ways: (a) by activating a negative self-schema that is responsible for the selective encoding and retrieval of information congruent with the current state, and (b) by providing contextual cues that result in the activation of mood-state-congruent memory associations. The effect of severity of pathology is also proposed to occur via one or both of two possible routes: (a) by disrupting trace processing and storage by its disorganizational nature, and/or (b) by producing low levels of effort in encoding and storage. (PsycINFO Database Record (c) 2010 APA, all rights reserved)