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)     

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)     

Working memory and work with memory: visual-spatial and further components of processing

Empirical and theoretical evidence for the concept of working memory is considered. We argue that the major weakness of this concept is its loose connection with the knowledge about background perceptive and cognitive processes. Results of two relevant experiments are provided. The first study demonstrated the classical chunking effect in a speeded visual search and comparison task, the proper domain of a large-capacity very short term sensory store. Our second study was a kind of extended levels-of-processing experiment. We attempted to manipulate visual, phonological, and (different) executive components of long-term memory in the hope of finding some systematic relationships between these forms of processing. Indeed, the results demonstrated a high degree of systematicity without any apparent need for a concept such as working memory for the explanation. Accordingly, the place for working memory is at all the interfaces where our metacognitive strategies interfere with mostly domain-specific cognitive mechanisms. Working memory is simply our work with memory.     

Mediators of long-term memory performance across the life span.

An individual-differences approach was used to examine the component processes that predict episodic long-term memory performance. A total of 301 participants ages 20-90 received a 7-hr cognitive battery across 3 days. Key constructs hypothesized to affect long-term memory function were assessed, including multiple measures of working memory and perceptual speed. Latent-construct, structural equation modeling was used to examine the relationship of these measures and age to different types of long-term memory tasks. Speed was a key construct for all 3 types of memory tasks, mediating substantial age-related variance; working memory was a fundamental construct for free and cued recall but not spatial memory. The data suggest that both speed and working memory are fundamental to explaining age-related changes in cognitive aging but that the relative contributions of these constructs vary as a function of the type of memory task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Varieties of working memory as seen in biology and in connectionist/control architectures

Biological and computational concepts that underlie the nature of working memory are briefly reviewed. The conceptualization of working memory has changed dramatically in the last 30 years. Current biological work has monitored several aspects of memory, including activation decay, sustained activation, long-term connection change, and differential structures for episodic (hippocampal formation) and procedural learning. Current connectionist modeling has identified factors including multiple-region-based processing, control processing as well as data storage, tradeoffs between fast- and slow-connection-change learning effects, and the speeding of acquisition via multiple levels of learning. The need to relate the biological, behavioral, and computational constraints into models of working memory is discussed. Finally, conceptualizations of working memory must acknowledge the need for human learning systems to be robust enough to operate in a dynamic world.     

Similarities and differences between working memory and long-term memory: Evidence from the levels-of-processing span task.

Two experiments compared the effects of depth of processing on working memory (WM) and long-term memory (LTM) using a levels-of-processing (LOP) span task, a newly developed WM span procedure that involves processing to-be-remembered words based on their visual, phonological, or semantic characteristics. Depth of processing had minimal effect on WM tests, yet subsequent memory for the same items on delayed tests showed the typical benefits of semantic processing. Although the difference in LOP effects demonstrates a dissociation between WM and LTM, we also found that the retrieval practice provided by recalling words on the WM task benefited long-term retention, especially for words initially recalled from supraspan lists. The latter result is consistent with the hypothesis that WM span tasks involve retrieval from secondary memory, but the LOP dissociation suggests the processes engaged by WM and LTM tests may differ. Therefore, similarities and differences between WM and LTM depend on the extent to which retrieval from secondary memory is involved and whether there is a match (or mismatch) between initial processing and subsequent retrieval, consistent with transfer-appropriate-processing theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is working memory still working?

The current state of A. D. Baddeley and G. J. Hitch's (1974) multicomponent working memory model is reviewed. The phonological and visuospatial subsystems have been extensively investigated, leading both to challenges over interpretation of individual phenomena and to more detailed attempts to model the processes underlying the subsystems. Analysis of the controlling central executive has proved more challenging, leading to a proposed clarification in which the executive is assumed to be a limited capacity attentional system, aided by a newly postulated fourth system, the episodic buffer. Current interest focuses most strongly on the link between working memory and long-term memory and on the processes allowing the integration of information from the component subsystems. The model has proved valuable in accounting for data from a wide range of participant groups under a rich array of task conditions. Working memory does still appear to be working. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Processing speed, working memory, and IQ: A developmental model of cognitive deficits following cranial radiation therapy.

IQ decrements following cranial radiation therapy (CRT) for acute lymphoblastic leukemia (ALL) are most apparent years after treatment. The authors examined a developmental model for delayed deficits by evaluating the relationship between processing speed, working memory, and IQ in long-term survivors of childhood ALL (n?=?27) compared with demographically matched controls (n?≠??7). The ALL group treated with CRT showed deficits in IQ, working memory, and processing speed relative to controls. Differences in IQ between the CRT group and controls were mediated by differences in working memory. Processing speed did not fully account for the working memory deficit in the CRT group. Participants with ALL treated only with chemotherapy showed similar working memory and processing speed as matched controls. Data suggest that deficits in processing speed and working memory following CRT may underlie declines in IQ. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory and aphasia

This study investigated the relationship between working memory capacity and reading comprehension in aphasia. A measurement of working memory capacity was obtained using a modified version of Daneman and Carpenter's (1980) Reading Span Task. Sets of sentences ranging in length from one to six words were presented to 22 aphasic subjects who were required to retain the terminal words following each sentence for subsequent recognition. The maximum number of words retrieved was used as an index of working memory capacity. Two versions of the task (listening and reading) were presented depending on the subjects' ability to read. Strong positive correlations were found between working memory capacity, reading comprehension, and language function. These results support the notion that the ability of aphasic individuals to comprehend language is predictable from their working memory capacities.     

Are working memory deficits in bipolar disorder markers for psychosis?

Working memory deficits have been identified in bipolar disorder, but there is evidence suggesting that these deficits may be markers for psychosis rather than affective disorder. The current study examined this issue by comparing two groups of individuals with bipolar disorder, one with psychotic features and one without psychotic features, with a group of normal controls. Working memory was conceptualized as a multicomponent system that includes auditory and visuospatial short-term stores, executive control processes, and an episodic buffer that allows for communication between short- and long-term memory stores (Baddeley & Logie, 1999). Results indicated that only executive control processes significantly differentiated the psychotic and nonpsychotic bipolar groups, although visuospatial working memory differentiated both bipolar groups from controls. The results support the idea that some aspects of working memory performance are markers for psychosis, while others may be more general markers for bipolar disorders. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The relationships of working memory, secondary memory, and general fluid intelligence: Working memory is special.

Recent efforts have been made to elucidate the commonly observed link between working memory and reasoning ability. The results have been inconsistent, with some work suggesting that the emphasis placed on retrieval from secondary memory by working memory tests is the driving force behind this association (Mogle, Lovett, Stawski, & Sliwinski, 2008), whereas other research suggests retrieval from secondary memory is only partly responsible for the observed link between working memory and reasoning (Unsworth & Engle, 2006, 2007). In the present study, we investigated the relationship between processing speed, working memory, secondary memory, primary memory, and fluid intelligence. Although our findings show that all constructs are significantly correlated with fluid intelligence, working memory—but not secondary memory—accounts for significant unique variance in fluid intelligence. Our data support predictions made by Unsworth and Engle (2006, 2007) and suggest that the combined need for maintenance and retrieval processes present in working memory tests makes them special in their prediction of higher order cognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory and the vividness of imagery.

The working memory framework was used to investigate the factors determining the phenomenological vividness of images. Participants rated the vividness of visual or auditory images under control conditions or while performing tasks that differentially disrupted the visuospatial sketchpad and phonological loop subsystems of working memory. In Experiments 1, 2, and 6, participants imaged recently presented novel visual patterns and sequences of tones; ratings of vividness showed the predicted interaction between stimulus modality and concurrent task. The images in experiments 3, 4, 5, and 6 were based on long-term memory (LTM). They also showed an image modality by task interaction, with a clear effect of LTM variables (meaningfulness, activity, bizarreness, and stimulus familiarity), implicating both working memory and LTM in the experience of vividness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visuospatial cues for reinstating mental models in working memory during interrupted reading.

Reading involves constructing a mental representation in long-term working memory of the world described by the text. Disrupting short-term working memory can interfere with the maintenance of mental models (sets of retrieval cues) needed to access these representations, producing detrimental effects on reading time. In two experiments, subjects read passages that included pairs of coreferential sentences interrupted by unrelated text. As in previous research, reading times increased for the first sentence after the interruption, likely reflecting a reinstatement process for mental models in working memory. In the present research, pictures were provided as visuospatial cues to aid the reinstatement process. The interruption effect was found to be smaller with pictures related to the passages than with unrelated pictures (Experiment 1) or titles (Experiment 2); however, both of these effects occurred only for slow readers. The authors hypothesize that slow readers take the time needed to integrate visuospatial information into their mental models, providing more resilient access to long-term working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Models of visuospatial and verbal memory across the adult life span.

The authors investigated the distinctiveness and interrelationships among visuospatial and verbal memory processes in short-term, working, and long-term memories in 345 adults. Beginning in the 20s, a continuous, regular decline occurs for processing-intensive tasks (e.g., speed of processing, working memory, and long-term memory), whereas verbal knowledge increases across the life span. There is little differentiation in the cognitive architecture of memory across the life span. Visuospatial and verbal working memory are distinct but highly interrelated systems with domain-specific short-term memory subsystems. In contrast to recent neuroimaging data, there is little evidence for dedifferentiation of function at the behavioral level in old compared with young adults. The authors conclude that efforts to connect behavioral and brain data yield a more complete understanding of the aging mind. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial working memory is independent of hippocampal CA1 long-term potentiation in rats.

This study investigated the relationship between spatial working memory and hippocampal long-term potentiation (LTP) using the allocentric place discrimination task (APDT) in rats, in which the selection accuracy is a good index for spatial working memory. Either the selective M1 muscarinic receptor antagonist pirenzepine (50 μg) or the choline uptake inhibitor hemicholinium-3 (5 μg) impaired APDT selection accuracy, but neither affected the induction of LTP in the hippocampal CA1 region in anesthetized rats. In contrast, the selective N-methyl-{d}-aspartate receptor antagonist D-amino-5-phosphonopentanoate (200 nmol) did not impair APDT selection accuracy but completely blocked hippocampal CA1 LTP. These results suggest that spatial working memory is independent of hippocampal CA1 LTP and that the central cholinergic system is involved in spatial working memory, but not through the modulation of hippocampal CA1 LTP. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working and long-term memory deficits in schizophrenia: Is there a common prefrontal mechanism?

This study tested the hypothesis that dorsolateral prefrontal cortex deficits contribute to both working memory and long-term memory disturbances in schizophrenia. It also examined whether such deficits were more severe for verbal than nonverbal stimuli. Functional magnetic resonance imaging was used to assess cortical activation during performance of verbal and nonverbal versions of a working memory task and both encoding and recognition tasks in 38 individuals with schizophrenia and 48 healthy controls. Performance of both working memory and long-term memory tasks revealed disturbed dorolateral prefrontal cortex activation in schizophrenia, although medial temporal deficits were also present. Some evidence was found for more severe cognitive and functional deficits with verbal than nonverbal stimuli, although these results were mixed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term study of chronic oral aluminum exposure and spatial working memory in rats.

The authors report an effort to advance animal models that mimic the cognitive decline of Alzheimer's disease. Rats were trained and repeatedly tested in a spatial delayed matching-to-position paradigm in the water maze, with the location of the submerged platform changing between, but not within, days. After Trial 1 (random search) and intertrial intervals of 30 s or 1 hr, memory was tested in Trial 2. Young rats quickly acquired this task and were repeatedly tested after different intervals over 7 months, with a slight increase in performance toward the end of testing, but no difference in latencies between delays. Oral long-term treatment of 1 group with 0.1 % aluminum caused no delay-dependent working memory deficit. This testing protocol may enable between- and within-subject long-term assessment of spatial working memory before and after drug treatment and may prove useful in animal models of progressive cognitive decline. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Divergent trajectories in the aging mind: Changes in working memory for affective versus visual information with age.

Working memory mediates the short-term maintenance of information. Virtually all empirical research on working memory involves investigations of working memory for verbal and visual information. Whereas aging is typically associated with a deficit in working memory for these types of information, recent findings suggestive of relatively well-preserved long-term memory for emotional information in older adults raise questions about working memory for emotional material. This study examined age differences in working memory for emotional versus visual information. Findings demonstrate that, despite an age-related deficit for the latter, working memory for emotion was unimpaired. Further, older adults exhibited superior performance on positive relative to negative emotion trials, whereas their younger counterparts exhibited the opposite pattern. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working and strategic memory deficits in schizophrenia.

Working memory and its contribution to performance on strategic memory tests in schizophrenia were studied. Patients (n?=?18) and control participants (n?=?15), all men, received tests of immediate memory (forward digit span), working memory (listening, computation, and backward digit span), and long-term strategic (free recall, temporal order, and self-ordered pointing) and nonstrategic (recognition) memory. Schizophrenia patients performed worse on all tests. Education, verbal intelligence, and immediate memory capacity did not account for deficits in working memory in schizophrenia patients. Reduced working memory capacity accounted for group differences in strategic memory but not in recognition memory. Working memory impairment may be central to the profile of impaired cognitive performance in schizophrenia and is consistent with hypothesized frontal lobe dysfunction associated with this disease. Additional medial-temporal dysfunction may account for the recognition memory deficit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory and the syndromes of schizotypal personality

The aim of this study was to investigate dorsolateral prefrontal function, as assessed by a spatial working memory task, in relation to the syndromal features of schizotypal personality. We found a weak association between a self-report measure of schizotypy and the working memory performance. Those with a high score on the schizotypal personality questionnaire tended to make more errors on the spatial working memory task. One sub-scale of the schizotypal personality questionnaire that taps into social functioning was significantly correlated with working memory deficit. This result suggests the presence of subtle prefrontal deficit in a sub-group of psychometrically ascertained schizotypic individuals and renders support for the past reports of working memory deficit in schizophrenia and schizotypy.