The role of retrieval in schizophrenic memory deficit.

To distinguish between information that is unavailable or inaccessible in the schizophrenic's memory store, 48 schizophrenics and 48 normals learned 3 lists of categorized words. The lists were either cued or not cued at recall. Demographic and pretest measures validated the diagnosis of schizophrenia and indicated no significant differences between the experimental groups on age, education, intelligence, or categorizing ability. Results indicate that under conditions where the input did not exceed the limits of immediate memory span, schizophrenic memory deficit could be explained in terms of an "inaccessibility" of items due to a retrieval dysfunction. Under conditions where input exceeded these limits, the recall analysis was suggestive of an "unavailability" of items in the memory store. It is concluded that schizophrenics suffer deficits throughout the information processing system rather than at any specific stage. The locus of breakdown was dependent on the task demands of the experimental situation. (French summary) (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of working memory capacity in retrieval.

The verbal fluency task that requires generation of category exemplars and appears to be an example of what M. Moscovitch (1995) calls a strategic test of memory retrieval. Four experiments explored the role of individual differences in working memory (WM) capacity on verbal fluency under various secondary load conditions. High WM participants consistently recalled more exemplars. However, load conditions caused a decline in recall only for high WM participants. Low WM participants showed no effect of secondary workload on exemplar generation. WM group differences and load effects were observed even in the 1st min of retrieval, which suggests that differences were not due to differences in knowledge. A model of retrieval is supported that relies on cue-based-automatic activation, monitoring of output for errors, controlled suppression of previously recalled items, and controlled strategic search. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Components of verbal working memory: evidence from neuroimaging

We review research on the neural bases of verbal working memory, focusing on human neuroimaging studies. We first consider experiments that indicate that verbal working memory is composed of multiple components. One component involves the subvocal rehearsal of phonological information and is neurally implemented by left-hemisphere speech areas, including Broca's area, the premotor area, and the supplementary motor area. Other components of verbal working memory may be devoted to pure storage and to executive processing of the contents of memory. These studies rest on a subtraction logic, in which two tasks are imaged, differing only in that one task presumably has an extra process, and the difference image is taken to reflect that process. We then review studies that show that the previous results can be obtained with experimental methods other than subtraction. We focus on the method of parametric variation, in which a parameter that presumably reflects a single process is varied. In the last section, we consider the distinction between working memory tasks that require only storage of information vs. those that require that the stored items be processed in some way. These experiments provide some support for the hypothesis that, when a task requires processing the contents of working memory, the dorsolateral prefrontal cortex is disproportionately activated.     

Imagery, encoding, and retrieval of information from memory: Some specific encoding-retrieval changes in Huntington's disease.

Used mixed lists of 10 high-imagery and 10 low-imagery words as stimuli in a prompted, free-recall experiment. On each trial, only words not recalled on the previous trial were presented again as stimuli. Normal controls recalled more words on each test of recall than did 8 41–53 yr old patients with Huntington's disease. Controls remembered more high-imagery words after fewer presentation trials and could recall them with greater consistency than low-imagery words. Patients with Huntington's disease required far more trials to remember words, never recalled all 20 words, and did not differentiate high- and low-imagery words with respect to their recall probability. Results indicate that these patients, unlike controls, cannot consistently retrieve responses that were recalled previously. Findings are discussed in terms of the relationship between encoding and retrieval processes. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of divided attention on encoding and retrieval processes in human memory: further support for an asymmetry

Despite a tradition in cognitive psychology that views encoding and retrieval processes in human memory as being similar, F. I. M. Craik, R. Govoni, M. Naveh-Benjamin and N. D. Anderson (1996) have recently shown that notable differences exist between the 2 when divided-attention manipulations are used. In this article, the authors further examined this asymmetry by using several manipulations that changed task demands at encoding and retrieval. The authors also used a secondary-task methodology that allowed a microlevel analysis of the secondary-task costs associated with encoding and retrieval. The results illustrated the resiliency of retrieval processes to manipulations involving different task demands. They also indicated different loci of attention demands at encoding and retrieval. The authors contend that whereas encoding processes are controlled, retrieval processes are obligatory but do require attentional resources for their execution.     

The effects of divided attention on encoding and retrieval processes in human memory.

The authors examined the effects of divided attention (DA) at encoding and retrieval in free recall, cued recall, and recognition memory in 4 experiments. Lists of words or word pairs were presented auditorily and recalled orally; the secondary task was a visual continuous reaction-time (RT) task with manual responses. At encoding, DA was associated with large reductions in memory performance, but small increases in RT; trade-offs between memory and RT were under conscious control. In contrast, DA at retrieval resulted in small or no reductions in memory, but in comparatively larger increases in RT, especially in free recall. Memory performance was sensitive to changes in task emphasis at encoding but not at retrieval. The results are discussed in terms of controlled and automatic processes and speculatively linked to underlying neuropsychological mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Layout geometry in encoding and retrieval of spatial memory.

Two experiments investigated whether the spatial reference directions that are used to specify objects' locations in memory can be solely determined by layout geometry. Participants studied a layout of objects from a single viewpoint while their eye movements were recorded. Subsequently, participants used memory to make judgments of relative direction (e.g., "Imagine you are standing at X, facing Y, please point to Z"). When the layout had a symmetric axis that was different from participants' viewing direction, the sequence of eye fixations on objects during learning and the preferred directions in pointing judgments were both determined by the direction of the symmetric axis. These results provide further evidence that interobject spatial relations are represented in memory with intrinsic frames of reference. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Verbal memory in drug-naive, newly diagnosed Parkinson's disease. The retrieval deficit hypothesis revisited.

Objective: The retrieval deficit hypothesis on memory impairment in patients with Parkinson's disease (PD) implies a selective impairment in recall of learned material with normal encoding, retention, and recognition. This hypothesis has been challenged by new data. We have therefore investigated verbal memory and learning in a large sample of newly diagnosed, drug na?ve, non-demented patients with PD. Method: From a sample of patients with PD from the Norwegian ParkWest study, 133 PD patients and 133 controls matched on sex, age, and education were included. The California Verbal Learning Test-2 (CVLT-2) was used to assess verbal memory. Results: Patients performed significantly worse than controls on free and cued recall as well as on recognition memory. Patients used the semantic clustering learning strategy significantly less extensively than the controls and the learning slope of the PD patients was significantly less steep. There was no difference in retention when controlling for encoding. Patients did not perform better on the recognition measure or on cued recall (d-prime), as compared to free recall. Executive functions explained a substantial part of the memory deficits. Conclusions: This study suggests that memory impairment in drug na?ve early PD to a large degree is a deficit of learning/ encoding and not of retention or retrieval. An implication is that the retrieval deficit hypothesis should be moderated in its general form. Executive deficits and less extensive use of the efficient semantic clustering learning strategy had a strong impact on learning and memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of spatial working memory in inhibition of return: evidence from divided attention tasks

Inhibition of return (IOR) refers to a bias against returning attention to a location that has been recently attended. In the present experiments, we examined the role of working memory in IOR by introducing secondary tasks (in the temporal interval between the cue and the target) that involved a working memory component. When the secondary task was nonspatial in nature (monitoring odd digits or adding digits), IOR was present, although overall reaction times were greater in the presence of the secondary task. When the task involved a spatial working memory load (remembering the directionality of arrows or the orientation of objects), IOR was eliminated. However, when the participants had incentive to process the directionality of an arrow but did not have to use any memory system, IOR persisted at peripheral locations. Overall, the results suggest that IOR is partially mediated by a spatial working memory system.     

Source memory in older adults: An encoding or retrieval problem?

Source memory has been found to be more affected by aging than item memory, possibly because of declining frontal function among older adults. In 4 experiments, the authors explored the role of the frontal lobes (FLs) in source memory, the extent to which they may be involved in the encoding and/or retrieval of source or context, and the conditions under which the source memory deficit in older people may be reduced or eliminated. Results indicated that only a subset of older adults show deficits in source memory, namely those with below average frontal function, and these deficits can be eliminated by requiring people at study to consider the relation between an item and its context. These results provide convincing evidence of the importance of frontal function during the encoding of source and suggest that older adults with reduced FL function fail to initiate the processes required to integrate contextual information with focal content during study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The time course of consolidation in visual working memory.

How long does it take to form a durable representation in visual working memory? Several theorists have proposed that this consolidation process is very slow. Here, we measured the time course of consolidation. Observers performed a change-detection task for colored squares, and shortly after the presentation of the first array, pattern masks were presented at the locations of each of the colored squares to disrupt representations that had not yet been consolidated. Performance on the memory task was impaired when the delay between the colored squares and the masks was short, and this effect became larger when the number of colored squares was increased. The rate of consolidation was approximately 50 ms per item, which is considerably faster than previous proposals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging and prospective memory: The influence of increased task demands at encoding and retrieval.

A feature of prospective memory tasks is that they tend to be embedded into other background activities. Two experiments examined how the demands of these background activities affect age differences in prospective memory. The first experiment showed that increasing the demands of the background activities (by adding a digit-monitoring task) significantly reduced prospective memory performance. Planned comparisons revealed that age differences in prospective memory were reliable only in the more demanding background condition. The second experiment revealed significant prospective memory declines when the demands were selectively increased at encoding for both younger and older adults. When the demands were selectively increased at retrieval, older adults were particularly affected. The authors propose a model that relies on both automatic retrieval processes and working memory resources to explain prospective memory remembering. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Anxiety, diazepam and retrieval from semantic memory

Diazepam, an anxiolytic, was administered to 16 undergraduate volunteers in a double-blind design. Eight subjects were selected to be high in State and Trait anxiety and were slow in recall on a semantic memory task compared to non-anxious subjects. Instead of alleviating this detrimental effect of anxiety on memory, diazepam slowed recall in both the anxious and non-anxious.     

A model of hippocampal memory encoding and retrieval: GABAergic control of synaptic plasticity

The current view of the role of GABAergic interneurones in cortical-network function has shifted from one of merely dampening neuronal activity to that of an active role in information processing. In this review, we explore a potential role of hippocampal GABAergic interneurones in providing spatial and temporal conditions for modifications of synaptic weights during hippocampus-dependent memory processes. We argue that knowledge of spatiotemporal activity patterns in distinct classes of interneurone is essential to understanding the cellular mechanisms underlying learning and memory.     

Memory dysfunction in multiple sclerosis: Its relation to working memory, semantic encoding, and implicit learning.

Memory disturbance is common in patients with multiple sclerosis (MS), as previously demonstrated on clinical memory tests of explicit learning using effortful retrieval paradigms. To better understand the mechanisms underlying memory failure, the authors compared the performance of 46 MS patients and 47 demographically matched normal controls on experimental tests of working memory, semantic encoding, and implicit memory. On the working memory task, MS patients demonstrated an exaggerated word length effect, which indicates a deficit in the control process of articulatory rehearsal. In contrast, MS patients demonstrated a normal buildup and release from proactive inhibition, which suggests intact semantic encoding. Finally, on priming and procedural memory tasks, MS patients performed without difficulty. The MS patients' test performance was not correlated with illness duration or course, severity of physical disability, or psychoactive medication use. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Context, time, and memory retrieval in the interference paradigms of Pavlovian learning.

Reviews research and theory on the "interference paradigms" in Pavlovian learning. In these situations (e.g., extinction, counterconditioning, and latent inhibition), a CS is associated with different unconditioned stimulus/stimuli (UCS) or outcomes in different phases of the experiment; retroactive interference, proactive interference, or both are often observed. In all of the paradigms, contextual stimuli influence performance, and when information is available, so does the passage of time. Memories of both phases are retained, and performance may depend on which is retrieved. Despite the similarity of the paradigms, conditioning theories tend to explain them with separate mechanisms. They also do not provide an adequate account of the context's role, fail to predict the effects of time, and overemphasize the role of learning or storage deficits. By accepting 4 propositions about animal memory (i.e., contextual stimuli guide retrieval, time is a context, different memories are differentially dependent on context, and interference occurs at performance output), a memory retrieval framework can provide an integrated account of context, time, and performance in the various paradigms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The attentional demands of encoding and retrieval in younger and older adults: 2. Evidence from secondary task reaction time distributions.

Three studies examined the effects of encoding or retrieval on properties of secondary task reaction time (RT) distributions in younger and older adults. Relative to full attention conditions, encoding and retrieval increased secondary task RT medians and standard deviations more for older adults than for younger adults, and the age-related RT increase was most pronounced among the slowest RTs. Hierarchical regression analyses revealed two age-related mechanisms underlying these effects, which were interpreted as cognitive slowing and reductions in attentional resources. Cognitive slowing affects the entire RT distribution regardless of the memory task. By contrast, reduced attentional resources result in very long RTs, especially when the tasks require self-initiated encoding or retrieval operations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recognition memory for words and pictures: an event-related potential study

Event-related potentials (ERPs) were recorded during the test phase of recognition memory tests for words and pictures of objects. ERPs elicited by recognized items contained a temporo-parietally distributed positive shift (the parietal old/new effect), which was strongly left lateralized regardless of stimulus type. This finding suggests that the lateral distribution of the parietal old/new effect is unrelated to the lateralization of the memory functions supported by the medial temporal lobe memory system. The ERPs to pictures, but not to words, also demonstrated frontally distributed old/new effects, which shifted over time from a left- to a right-sided maximum. These effects may reflect the richer informational content associated with episodic memory for pictures.