Controlled Retrieval Processes Research Articles

Working memory training improves episodic memory in older people: transfer based on controlled retrieval processes.

The results of working memory (WM) training to improve episodic memory in older people are inconsistent. This inconsistency could be due to the fact that the episodic memory tests used do not share the same cognitive resources as the trained WM task. The aim of this study was to assess whether performance on an episodic memory test will improve only when this test requires controlled processes of retrieval of information from secondary memory or recollection, similar to the processes exercised during WM training. Fifty-five people over 60 years of age participated in the study: 27 were randomly assigned to the experimental group (EG) and the rest to the control group (CG). The EG was trained in complex span tasks. Before and after training, both groups were tested on episodic memory tests (a verbal and a visuospatial recognition test) and WM span tasks (reading, digit and spatial location). ANOVAs revealed a greater improvement of recollection estimates in the EG than in the CG for both verbal recognition (p = 0.023) and visuospatial recognition (p = 0.014). Our results provide support for a cognitive mechanism whose shared presence favored transfer from training on a WM task to a test of episodic memory. Consistent with our predictions, training on complex span tasks improved performance on recognition tests only when recall required a controlled search process in secondary memory, or recollection. We therefore stress the importance of identifying other cognitive resources that are susceptible to transfer from a training task to other untrained tasks. A better understanding of the phenomenon of transfer is crucial for the design of increasingly effective intervention programs for older people.

Divergent thinking modulates interactions between episodic memory and schema knowledge: Controlled and spontaneous episodic retrieval processes.

The ability to generate novel ideas, known as divergent thinking, depends on both semantic knowledge and episodic memory. Semantic knowledge and episodic memory are known to interact to support memory decisions, but how they may interact to support divergent thinking is unknown. Moreover, it is debated whether divergent thinking relies on spontaneous or controlled retrieval processes. We addressed these questions by examining whether divergent thinking ability relates to interactions between semantic knowledge and different episodic memory processes. Participants completed the alternate uses task of divergent thinking, and completed a memory task in which they searched for target objects in schema-congruent or schema-incongruent locations within scenes. In a subsequent test, participants indicated where in each scene the target object had been located previously (i.e., spatial accuracy test), and provided confidence-based recognition memory judgments that indexed distinct episodic memory processes (i.e., recollection, familiarity, and unconscious memory) for the scenes. We found that higher divergent thinking ability-specifically in terms of the number of ideas generated-was related to (1) more of a benefit from recollection (a controlled process) and unconscious memory (a spontaneous process) on spatial accuracy and (2) beneficial differences in how semantic knowledge was combined with recollection and unconscious memory to influence spatial accuracy. In contrast, there were no effects with respect to familiarity (a spontaneous process). These findings indicate that divergent thinking is related to both controlled and spontaneous memory processes, and suggest that divergent thinking is related to the ability to flexibly combine semantic knowledge with episodic memory.

Neural evidence for age-related differences in representational quality and strategic retrieval processes

Mounting behavioral evidence suggests that declines in both representational quality and controlled retrieval processes contribute to episodic memory decline with age. The present study sought neural evidence for age-related change in these factors by measuring neural differentiation during encoding of paired associates and changes in regional blood oxygenation level–dependent activity and functional connectivity during retrieval conditions that placed low (intact pairs) and high (recombined pairs) demands on controlled retrieval processes. Pattern similarity analysis revealed age-related declines in the differentiation of stimulus representations at encoding, manifesting as both reduced pattern similarity between closely related events and increased pattern similarity between distinct events. During retrieval, both groups increased recruitment of areas within the core recollection network when endorsing studied pairs, including the hippocampus and angular gyrus. In contrast, only younger adults increased recruitment of, and hippocampal connectivity with, lateral prefrontal regions during correct rejections of recombined pairs. These results provide evidence for age-related changes in representational quality and in the neural mechanisms supporting memory retrieval under conditions of high, but not low, control demand.

Control the source: Source memory for semantic, spatial and self-related items in patients with LIFG lesions

Patients with multimodal semantic deficits following stroke (‘semantic aphasia’) have largely intact knowledge, yet difficulty controlling conceptual retrieval to suit the circumstances. Although conceptual representations are thought to be largely distinct from episodic representations of recent events, controlled retrieval processes may overlap across semantic and episodic memory domains. We investigated this possibility by examining item familiarity and source memory for recent events in semantic aphasia following infarcts affecting left inferior frontal gyrus. We tested the hypothesis that the nature of impairment in episodic judgements reflects the need for control over retrieval: item familiarity might be relatively intact, given it is driven by strong cues (re-presentation of the item), while source recollection might be more impaired since this task involves resolving competition between several potential sources. This pattern was observed most strongly when the degree of competition between sources was higher, i.e., when non-meaningful sources had similar perceptual features, and existing knowledge was incongruent with the source. In contrast, when (i) spatial location acted as a strong cue for retrieval; (ii) existing knowledge was congruent with episodic memory and (iii) distinctiveness of sources was increased by means of self-referential processing, source memory reached normal levels. These findings confirm the association between deregulated control of semantic and episodic memory in patients with semantic aphasia and delineate circumstances that ameliorate or aggravate these deficits.

Multinomial models reveal deficits of two distinct controlled retrieval processes in aging and very mild Alzheimer disease.

Dual-process models of episodic retrieval reveal consistent deficits of controlled recollection in aging and Alzheimer disease (AD). In contrast, automatic familiarity is relatively spared. We extend standard dual-process models by showing the importance of a third capture process. Capture produces a failure to attempt recollection, which might reflect a distinct error from an inability to recollect when attempted (Jacoby et al. Journal of Experimental Psychology: General, 134(2), 131-148, 2005a). We used multinomial process tree (MPT) modeling to estimate controlled recollection and capture processes, as well as automatic retrieval processes, in a large group of middle-aged to older adults who were cognitively normal (N = 519) or diagnosed with the earliest detectable stage of AD (N = 107). Participants incidentally encoded word pairs (e.g., knee bone). At retrieval, participants completed cued word fragments (e.g., knee b_n_) with primes that were congruent (e.g., bone), incongruent (e.g., bend), or neutral (i.e., &&&) to the target (e.g., bone). MPT models estimated retrieval processes both at the group and the individual levels. A capture parameter was necessary to fit MPT models to the observed data, suggesting that dual-process models of this taskcan be contaminated by a capture process. In both group- and individual-level analyses, aging and very mild AD were associated with increased susceptibility to capture, decreased recollection, and no differences in automatic influences. These results suggest that it is important to consider two distinct modes of attentional control when modeling retrieval processes. Both forms of control (recollection and avoiding capture) are particularly sensitive to cognitive decline in aging and early-stage AD.

Acute stress and episodic memory retrieval: neurobiological mechanisms and behavioral consequences.

Episodic retrieval allows people to access memories from the past to guide current thoughts and decisions. In many real-world situations, retrieval occurs under conditions of acute stress, either elicited by the retrieval task or driven by other, unrelated concerns. Memory under such conditions may be hindered, as acute stress initiates a cascade of neuromodulatory changes that can impair episodic retrieval. Here, we review emerging evidence showing that dissociable stress systems interact over time, influencing neural function. In addition to the adverse effects of stress on hippocampal-dependent retrieval, we consider how stress biases attention and prefrontal cortical function, which could further affect controlled retrieval processes. Finally, we consider recent data indicating that stress at retrieval increases activity in a network of brain regions that enable reflexive, rapid responding to upcoming threats, while transiently taking offline regions supporting flexible, goal-directed thinking. Given the ubiquity of episodic memory retrieval in everyday life, it is critical to understand the theoretical and applied implications of acute stress. The present review highlights the progress that has been made, along with important open questions.

Controlled Retrieval of Specific Context Information in Children and Adults.

This study adapted a procedure used by Luo and Craik (2009) to examine whether developmental differences exist in the ability to use controlled retrieval processes to access the contextual details of memory representations. Participants from 3 age groups (mean ages 9, 12, and 25 years) were presented with words in 3 study contexts: with a black-and-white picture, with a color picture, or alone without a picture. Six recognition tests were then presented that varied in the demands (high or low) placed on the retrieval of specific contextual information. Each test consisted of a mixture of words that were old targets from 1 study context, distractors (i.e., previously studied words from a different context), and completely new words. A high-specificity and a low-specificity test list was paired with each test question, with high and low specificity being determined by the nature of the distractors used in a test list. High-specificity tests contained words that were studied in similar contexts: old targets (e.g., words studied with black-and-white pictures) and distractors (e.g., words studied with color pictures). In contrast, low-specificity tests contained words that were studied in dissimilar contexts: old targets (e.g., words studied with black-and-white pictures) and distractors (e.g., words previously studied without a picture). Relative to low-specificity tests, the retrieval conditions of high-specificity tests were assumed to place greater demands on the controlled access of specific contextual information. Analysis of recollection scores revealed that age differences were present on high-but not low-specificity tests, with the performance of 9-year-olds disproportionately affected by the retrieval demands of high-specificity tests.

The Neural Basis of Involuntary Episodic Memories

Voluntary episodic memories require an intentional memory search, whereas involuntary episodic memories come to mind spontaneously without conscious effort. Cognitive neuroscience has largely focused on voluntary memory, leaving the neural mechanisms of involuntary memory largely unknown. We hypothesized that, because the main difference between voluntary and involuntary memory is the controlled retrieval processes required by the former, there would be greater frontal activity for voluntary than involuntary memories. Conversely, we predicted that other components of the episodic retrieval network would be similarly engaged in the two types of memory. During encoding, all participants heard sounds, half paired with pictures of complex scenes and half presented alone. During retrieval, paired and unpaired sounds were presented, panned to the left or to the right. Participants in the involuntary group were instructed to indicate the spatial location of the sound, whereas participants in the voluntary group were asked to additionally recall the pictures that had been paired with the sounds. All participants reported the incidence of their memories in a postscan session. Consistent with our predictions, voluntary memories elicited greater activity in dorsal frontal regions than involuntary memories, whereas other components of the retrieval network, including medial-temporal, ventral occipitotemporal, and ventral parietal regions were similarly engaged by both types of memories. These results clarify the distinct role of dorsal frontal and ventral occipitotemporal regions in predicting strategic retrieval and recalled information, respectively, and suggest that, although there are neural differences in retrieval, involuntary memories share neural components with established voluntary memory systems.

Monetary rewards influence retrieval orientations

Reward anticipation during learning is known to support memory formation, but its role in retrieval processes is so far unclear. Retrieval orientations, as a reflection of controlled retrieval processing, are one aspect of retrieval that might be modulated by reward. These processes can be measured using the event-related potentials (ERPs) elicited by retrieval cues from tasks with different retrieval requirements, such as via changes in the class of targeted memory information. To determine whether retrieval orientations of this kind are modulated by reward during learning, we investigated the effects of high and low reward expectancy on the ERP correlates of retrieval orientation in two separate experiments. The reward manipulation at study in Experiment 1 was associated with later memory performance, whereas in Experiment 2, reward was directly linked to accuracy in the study task. In both studies, the participants encoded mixed lists of pictures and words preceded by high- or low-reward cues. After 24h, they performed a recognition memory exclusion task, with words as the test items. In addition to a previously reported material-specific effect of retrieval orientation, a frontally distributed, reward-associated retrieval orientation effect was found in both experiments. These findings suggest that reward motivation during learning leads to the adoption of a reward-associated retrieval orientation to support the retrieval of highly motivational information. Thus, ERP retrieval orientation effects not only reflect retrieval processes related to the sought-for materials, but also relate to the reward conditions with which items were combined during encoding.

Event-related potential evidence for separable automatic and controlled retrieval processes in proactive interference

Interference between competing memories is a major source of retrieval failure, yet, surprisingly little is known about how competitive memory activation arises in the brain. One possibility is that interference during episodic retrieval might be produced by relatively automatic conceptual priming mechanisms that are independent of strategic retrieval processes. Such priming-driven interference might occur when the competing memories have strong pre-existing associations to the retrieval cue. We used ERPs to measure the neural dynamics of retrieval competition, and investigated whether the ERP correlates of interference were affected by varying task demands for selective retrieval. Participants encoded cue words that were presented either two or four times, paired either with the same or different strongly associated words across repetitions. In a subsequent test, participants either selectively recalled each cue's most recent associate, or simply judged how many times a cue had been presented, without requiring selective recall. Interference effects on test performance were only seen in the recall task. In contrast, ERPs during test revealed an early posterior positivity for high interference items that was present in both retrieval tasks. This early ERP effect likely reflects a conceptual priming-related N400 reduction when many associations to a cue were pre-activated. A later parietal positivity resembling the ERP correlate of conscious recollection was found only in the recall task. The results suggest that early effects of proactive interference are relatively automatic and independent of intentional retrieval processes, consistent with suggestions that interference can arise through conceptual priming.

Choosing Our Words: Retrieval and Selection Processes Recruit Shared Neural Substrates in Left Ventrolateral Prefrontal Cortex

When we speak, we constantly retrieve and select words for production in the face of multiple possible alternatives. Our ability to respond in such underdetermined situations is supported by left ventrolateral prefrontal cortical (VLPFC) regions, but there is active debate about whether these regions support (1) selection between competing alternatives, (2) controlled retrieval from semantic memory, or (3) selection and controlled retrieval in distinct subregions of VLPFC (selection in mid-VLPFC and controlled retrieval in anterior VLPFC). Each of these theories has been supported by some prior evidence but challenged by other findings, leaving the debate unresolved. We propose that these discrepancies in the previous literature reflect problems in the way that selection and controlled retrieval processes have been operationalized and measured. Using improved measures, we find that shared neural substrates in left VLPFC support both selection and controlled retrieval, with no dissociation between mid and anterior regions. Moreover, selection and retrieval demands interact in left VLPFC, such that selection effects are greatest when retrieval demands are low, consistent with prior behavioral findings. These findings enable a synthesis and reinterpretation of prior evidence and suggest that the ability to respond in underdetermined situations is affected by both selection and retrieval mechanisms for verbal material subserved by left VLPFC, and these processes interact in meaningful ways.

Investigating the attentional demands of recognition memory: Manipulating depth of encoding at study and level of attention at test

Two experiments investigated the effects of divided attention at test after manipulating levels of processing at study. In Experiment 1 items were studied either intact or as anagrams. In Experiment 2 items were studied with either full or divided attention (DA). In both experiments participants carried out a recognition test with either full or divided attention. Analysis of remember and know responses revealed that DA at test had no effect on remember responses to anagrams or to items studied with full attention. In contrast, Know responses decreased with DA at test, and this occurred for items studied in both deep and shallow encoding conditions. The present study confirms recent findings (Knott & Dewhurst, 2007a) that knowing can rely on more controlled retrieval processes, whereas remembering can rely on more automatic retrieval processes. Differences in the controlled processes associated with recollection and familiarity and remember and know responses are discussed.

The Medial Temporal Lobe and the Left Inferior Prefrontal Cortex Jointly Support Interference Resolution in Verbal Working Memory

During working memory retrieval, proactive interference (PI) can be induced by semantic similarity and episodic familiarity. Here, we used fMRI to test hypotheses about the role of the left inferior frontal gyrus (LIFG) and the medial temporal lobe (MTL) regions in successful resolution of PI. Participants studied six-word lists and responded to a recognition probe after a short distracter period. We induced semantic PI by using study lists containing words within the same semantic category (e.g., animals). We also measured PI induced by recent study, which should increase episodic familiarity, by comparing recent negative probes (lures studied in previous trial) to distant negative probes (lures that had not been presented within a block). Resolving both types of PI resulted in enhanced activation in LIFG and MTL regions. We propose that the LIFG and the MTL support successful resolution of interference via controlled retrieval processes that serve to recover detailed episodic (e.g., list-specific or source) information: Specifically, the data suggest that BOLD activation in the LIFG reflects the deployment of controlled retrieval operations, regardless of whether the retrieval attempt succeeds in recovering the target information, whereas MTL activation specifically reflects access to relevant episodic information that serves to successfully resolve PI.

Age differences in recollection: Specificity effects at retrieval

Three experiments were conducted to examine the effect of specificity at retrieval on the size of age differences in recollection. Participants encoded words in different contexts and were given recognition tests. Some of the test lists were constructed so that participants had to recollect specific aspects of the initial encoding events, whereas other test lists required participants to recollect only general aspects. Older adults showed reduced levels of recollection relative to younger adults for the high specificity tests, but not for the low specificity tests (Experiment 1). Encoding manipulations improved (Experiment 2) or reduced (Experiment 3) recollection levels but the effects did not interact with the specificity effect, whereas dividing attention (DA) at retrieval (Experiment 3) in younger adults resembled the effect of aging. The results suggest that older adults have greater difficulties in carrying out controlled retrieval processes to access specific information compared to their younger counterparts.

Controlled retrieval processing: Task-dependent constraints

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Divided attention at retrieval disrupts knowing but not remembering

The view that remember and know responses can be explained within a dual-process framework has recently been questioned (e.g., Gardiner, Konstantinou, Karayianni, & Gregg, 2005). The aims of the present study were to investigate further discrepancies between remember/know (R/K) studies and dual-process models of recognition memory. In two experiments participants were required to make old/new and R/K decisions under full and divided attention conditions. Experiment 1 used a two-step R/K procedure and showed that attention during retrieval reduced overall recognition performance. Experiment 2 used a one-step R/K procedure and showed that dividing attention at retrieval only affected know responses, suggesting that knowing but not remembering relies on controlled retrieval processes. These findings and findings from recent research provide evidence that is inconsistent with the dual-process explanation for R/K research.

Ventrolateral prefrontal cortex and tactile memory disambiguation in the human brain

Tactile sensory information is first channeled from the primary somatosensory cortex on the postcentral gyrus to the parietal opercular region (i.e., the secondary somatosensory cortex) and the rostral inferior parietal lobule and, from there, to the prefrontal cortex, with which bidirectional connections exist. Although we know that tactile memory signals can be found in the prefrontal cortex, the contribution of the different prefrontal areas to tactile memory remains unclear. The present functional MRI study shows that a specific part of the prefrontal cortex in the human brain, namely the midventrolateral prefrontal region (cytoarchitectonic areas 47/12 and 45), is involved in active controlled retrieval processing necessary for the disambiguation of vibrotactile information in short-term memory. Furthermore, we demonstrate that this particular part of the prefrontal cortex interacts functionally with the secondary somatosensory areas in the parietal operculum and the rostral inferior parietal lobule during controlled processing for the retrieval of specific tactile information.

Controlled retrieval processing in recognition memory exclusion tasks

ERPs were acquired in the test phases of two memory tasks where three classes of word were presented: (i) words encountered in a study phase (studied words), (ii) words presented at test for the first time (new words), and (iii) new words repeated after a lag of 7–9 words (repeated test words). In Experiment 1, participants responded on one key to studied words (targets) and on a second to repeated test words (non-targets) as well as to new words. In Experiment 2, participants responded on one key to repeated test words (targets) and on a second key to new and studied words (non-targets). The likelihood of a correct response to a target was higher in Experiment 2 than in Experiment 1. In both experiments, the focus for the ERP analyses was on parietally distributed ERP old/new effects, which are assumed to index recollection. Reliable parietal old/new effects were obtained for targets as well as non-targets in Experiment 1, but for targets only in Experiment 2. This pattern of data is consistent with previous suggestions that, when the likelihood of recollecting information about targets is high, participants use the success or failure of an attempt to recollect information about targets as the basis for distinguishing between targets and all other classes of test word. The findings in these two experiments are informative because they: (i) generalise those obtained in previous work to a different exclusion paradigm, (ii) add emphasis to claims regarding the potential utility of this particular paradigm in studies where changes in memory control according to age are assessed, and (iii) highlight important considerations when behavioural data obtained in exclusion tasks are employed in order to make estimates of the relative contributions of recollection and familiarity to task performance.

Selecting Among Competing Alternatives: Selection and Retrieval in the Left Inferior Frontal Gyrus

It has been widely argued that the left inferior frontal gyrus (LIFG) is involved in the control of retrieval of information from long-term memory. Recent claims that the LIFG is involved in selecting among semantic alternatives have been challenged on the grounds that the manipulation of selection demands may have been confounded with controlled retrieval. The current study used an event-related functional magnetic resonance paradigm to re-examine the possibility that LIFG activation is involved in selection processes. In order to minimize potential confounding effects of controlled retrieval, we used an automatic retrieval task (picture naming) and held retrieval demands constant, while varying selection demands by way of competitor priming from earlier semantically related trials. We found significant activation in LIFG as a function of increased selection demands; activation centred on two peaks, one in anterior LIFG and a second more superior and posterior region. These data support the view that LIFG plays a role in selection among semantic information, even in the absence of controlled retrieval processes.

Memoria automática observada en esquizofrenia mediante el procedimiennto de disociación de procesos

The nature of memory impairment in schizophrenia has been a matter of debate for a long time. It is normally agreed that both registration and storage are maintained, but that retrieval is impaired. We believe that this impairment could be located in controlled retrieval processes, as we found that when only automatic processes are required, performance is similar to that of control subjects. Furthermore, as regards controlled processes, the group of patients will have the same reaction for certain stimuli (uncommon words) as for normal words, a hypothesis that was not sustained. Finally, the expected relationship between positive and disorganised symptoms, such as possible phenomena of a lack of cognitive inhibition, frontal neuropsychological dysfunctions and decrease in controlled processes, was not sustained either. We use special methods, such as the “process-dissociation procedure” (Jacoby, 1991), that estimates more purely both types of processes, in a word stem completion task.