Visual working memory phenomena based on categorical tasks replicate using a continuous measure: A simple interpretation and some methodological considerations.

An increasingly popular method for investigating visuospatial working memory assumes stored features of objects such as color and orientation vary along continua subject to internal noise. It adapts the stimulus adjustment procedure from perceptual psychophysics to assess the precision with which stored features are represented in memory. This contrasts with methods using discrete, categorical measures of feature retention. The current study examined the replicability of some phenomena documented using conventional methodology when assessed using a continuous measure of feature recall. These concern memory for a short series of objects and include effects of recency, prioritizing an individual object, and presenting an irrelevant additional object after the last item (a poststimulus 'suffix'). In two experiments we find broadly similar results using a continuous measure of color-orientation binding to those obtained previously using categorical measures, with small differences we regard as minor. We interpret the convergence between methods in terms of a simple analogy between categorical memory and categorical perception whereby categorical retrieval involves the application of a discrete criterion to an underlying continuum of stored feature information. We conclude by discussing some of the advantages and limitations of continuous and categorical measures of retention.

Forgetting rates of gist and peripheral episodic details in prose recall.

In a seminal study, Slamecka and McElree showed that the degree of initial learning of verbal material affected the intercepts but not the slopes of forgetting curves. However, more recent work has reported that memories for central events (gist) and memory for secondary details (peripheral) were forgotten at different rates over periods of days, with gist memory retained more consistently over time than details. The present experiments aimed to investigate whether qualitatively different types of memory scoring (gist vs. peripheral) are forgotten at different rates in prose recall. In three experiments, 232 participants listened to two prose narratives and were subsequently asked to freely recall the stories. In the first two experiments participants were tested repeatedly after days and a month, while in the third experiment they were tested only after a month to control for repeated retrieval. Memory for gist was higher than for peripheral details, which were forgotten at a faster rate over a month, with or without the presence of intermediate recall. Moreover, repeated retrieval had a significant benefit on both memory for gist and peripheral details. We conclude that the different nature of gist and peripheral details leads to a differential forgetting in prose free recall, while repeated retrieval does not have a differential effect on the retention of these different episodic details.

Rate of forgetting is independent from initial degree of learning across different age groups.

It is well established that the more we learn, the more we remember. It is also known that our ability to acquire new information changes with age. An important remaining issue for debate is whether the rate of forgetting depends on initial degree of learning. In two experiments, following the procedure used by Slamecka and McElree (Exp 3), we investigated the relationship between initial degree of learning and rate of forgetting in both younger and older adults. A set of 36 (Exp 1) and a set of 30 (Exp 2) sentences was presented four times. Forgetting was measured via cued recall at three retention intervals (30 s, 1 hr, and 24 hr). A different third of the original sentences was tested at each delay. The results of both experiments showed that initial acquisition is influenced by age. However, the rate of forgetting proved to be independent from initial degree of learning. The conclusion is that rates of forgetting are independent from initial degree of learning.

Intact high-resolution working memory binding in a patient with developmental amnesia and selective hippocampal damage.

Debate continues regarding the possible role of the hippocampus across short-term and working memory tasks. The current study examined the possibility of a hippocampal contribution to precise, high-resolution cognition and conjunctive memory. We administered visual working memory tasks featuring a continuous response component to a well-established developmental amnesic patient with relatively selective bilateral hippocampal damage (Jon) and healthy controls. The patient was able to produce highly accurate response judgments regarding conjunctions of color and orientation or color and location, using simultaneous or sequential presentation of stimuli, with no evidence of any impairment in working memory binding, categorical accuracy, or continuous precision. These findings indicate that hippocampal damage does not necessarily lead to deficits in high-resolution cognitive performance, even when the damage is severe and bilateral.

The effect of selective retrieval practice on forgetting rates in younger and older adults.

Recent findings demonstrate that selective retrieval practice (SRP), specifically the retrieval of subparts of material, not just retrieval of the entire encoded material, can enhance later memory performance. We present two experiments that investigated whether SRP enhances memory performance among older adults. We also examined to what extent this effect is enhanced by the level of integration of the studied material. We used a design that contrasts the performance of the groups in conditions with and without SRP. This design also allowed us to examine whether older adults present with faster forgetting compared to younger individuals when assessed over a long delay. In both experiments, participants were exposed to a learning phase in which they had to achieve a criterion of 70% correct recall and were then tested at 1 month. The SRP for the experimental group occurred 1 day and 1 week after the learning phase (the control group received no SRP). None of the items at 1-month delay was probed in the retrieval practice. Experiment 1 used integrated material (four short stories). Experiment 2 used less integrated material (16 sentences). Both age groups showed a decline in memory performance over 1 month, however, groups tested repeatedly showed better performance (irrespective of age or material). (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Rate of forgetting is independent of initial degree of learning.

It is commonly assumed that the rate of forgetting depends on initial degree of learning. Hence, comparison of forgetting across groups is usually carried out equating initial performance. However, these matching procedures add confounding variables. In four experiments, following Slamecka and McElree (1983, Exp 3), we challenge this assumption through manipulating initial acquisition by varying the number of presentations of the material and studying the effect on rate of subsequent forgetting. A set of 36 sentences was presented either visually or auditorily. Different participants were exposed to the material two, four or six times. Forgetting was measured by means of a cued recall test at three time-intervals (30 s, 1 day and 1 week in experiments 1 and 2; 30 s, 1 day, and 3 days in experiments 3 and 4). A different subset of 12 sentences was tested at each delay. The outcome of these experiments showed that the initial acquisition depends on number of learning trials. However, the rate of forgetting proved to be independent of initial acquisition. This pattern remains constant across modalities of presentation and of the number of learning trials. The conclusion is that forgetting does not depend on initial acquisition.

Translating words into actions in working memory: The role of spatial-motoric coding.

Research from a working memory perspective on the encoding and temporary maintenance of sequential instructions has established a consistent advantage for enacted over verbal recall. This is thought to reflect action planning for anticipated movements at the response phase. We describe five experiments investigating this, comparing verbal and enacted recall of a series of action-object pairings under different potentially disruptive concurrent task conditions, all requiring repetitive movements. A general advantage for enacted recall was observed across experiments, together with a tendency for concurrent action to impair sequence memory performance. The enacted recall advantage was reduced by concurrent action for both fine and gross concurrent movement with the degree of disruption influenced by both the complexity and the familiarity of the movement. The results are discussed in terms of an output buffer store of limited capacity capable of holding motoric plans for anticipated action.

Is the study of memory unduly preoccupied with its sins?

A broad functional approach is taken to the analysis of human memory. The overall importance of episodic memory, the capacity to remember specific events, is illustrated by the devastating effect that loss of this aspect of memory has on the capacity to cope in the case of densely amnesic patients. Recent applied research has however focussed heavily on factors compromising the reliability of eyewitness testimony in the forensic field and on the creation of false memories. While acknowledging the progress made on this issue, it presents two dangers. The first is practical, the danger of generalising too readily from laboratory-influenced simulations that differ in important ways from the context to which they are applied. This suggests a need for fewer but more realistically representative studies. The second is a broad theoretical issue, that of extending the findings from this important but limited applied area, within which precise detail may be crucial, to the whole of memory, consequently failing to appreciate its many strengths.

Detecting accelerated long-term forgetting: A problem and some solutions.

While many memory disorders occur with normal rates of forgetting, an accelerated rate of long-term forgetting (ALF) may occur, sometimes in the absence of a learning deficit. Detecting ALF presents a problem as it is desirable that the learned material is re-tested after each of several delays. This may result in earlier retrievals confounding later tests, with evidence suggesting that both positive and negative interaction can occur between successive tests. An earlier study (Baddeley et al., 2019) tested cued recall of a series of four crimes or four visual scenes by probing a different sample of features from all four crimes/scenes at each delay. Even though no question was asked twice, the interpolated tests markedly reduced the rate of forgetting. We suggest that this decelerated forgetting effect may result from the retrieval of probed features activating other associated features within that episode, hence facilitating their recall on subsequent tests. If so, the effect should be removed when only single and separate episodes, or individual items, are tested at each delay. We test this by probing a separate episode at each delay (Experiment 1), or by replacing integrated episodes with recognition memory for isolated words (Experiments 2 and 3) or visual scenes (Experiments 4 and 5). As predicted, we find no reduction in the rate of forgetting, in contrast to our earlier studies. The theoretical and clinical implications of our results are discussed. We conclude that the previously developed Crimes and Four Doors Tests (Baddeley et al., 2019) and the present single item recognition tests are complementary and are both likely to be necessary to ensure the reliable detection of ALF.

Developing the Concept of Working Memory: The Role of Neuropsychology1.

The evolution of the concept of a multicomponent working memory is described with particular reference to the contribution from neuropsychology. Early evidence from patients with the classic amnesic syndrome, together with others showing the opposite deficit of impaired short-term but preserved long-term memory argued strongly for a separation between long- and short-term memory systems. Simulation of the short-term deficit in healthy participants using a dual task approach suggested the need to assume a three component system serving as a multi-purpose working memory comprising an overall attentional control system, the Central Executive, aided by separable temporary buffer stores for phonological and visuospatial information. An account is then given of the way in which evidence from patients was combined with the study of healthy participants to test and expand the model over subsequent years. This led to the need to propose a fourth component, the Episodic Buffer, a system that combines information from multiple sources and makes it accessible to conscious awareness. I conclude with a brief account of how the multicomponent approach resembles and differs from that of other current models of working memory.

The use of novel measures to detect Accelerated Long-term forgetting in people with epilepsy: The Crimes Test and Four Doors Test.

Most patients with memory disorders appear to forget at a relatively normal rate. Hence testing retention beyond the initial test session becomes unnecessary. However, it is now well established that a subsample of patients, most notably people with epilepsy, can show substantially increased forgetting rates even when acquisition rate is normal, raising the need for new tests focused on the assessment of long-term forgetting. Our study is part of the process of developing two such tests. Both focus on the need to test the same person several times and address the problem that each successive test may interfere with the memory of the event being tested. Depending on conditions, such effects can be substantial and may be either positive or negative. The Crimes and Four Doors Tests tackle this problem by presenting easily memorised episodes or scenes, from which a different sample of features is tested at each delay by telephone. We apply these two novel tests to assess rates of forgetting in groups of people with epilepsy and a matched control group. Both the visual and verbal tests showed clear evidence of accelerated forgetting in the epilepsy group supporting the potential value of the tests as convenient and sensitive measures of the rate of long-term forgetting.

Can valuable information be prioritized in verbal working memory?

Though there is substantial evidence that individuals can prioritize more valuable information in visual working memory (WM), little research has examined this in the verbal domain. Four experiments were conducted to investigate this and the conditions under which effects emerge. In each experiment, participants listened to digit sequences and then attempted to recall them in the correct order. At the start of each block, participants were either told that all items were of equal value, or that an item at a particular serial position was worth more points. Recall was enhanced for these higher value items (Experiment 1a), a finding that was replicated while rejecting an alternative account based on distinctiveness (Experiment 1b). Thus, valuable information can be prioritized in verbal WM. Two further experiments investigated whether these boosts remained when participants completed a simple concurrent task disrupting verbal rehearsal (Experiment 2), or a complex concurrent task disrupting verbal rehearsal and executive resources (Experiment 3). Under simple concurrent task conditions, prioritization boosts were observed, but with increased costs to the less valuable items. Prioritization effects were also observed under complex concurrent task conditions, although this was accompanied by chance-level performance at most of the less valuable positions. A substantial recency advantage was also observed for the final item in each sequence, across all conditions. Taken together, this indicates that individuals can prioritize valuable information in verbal WM even when rehearsal and executive resources are disrupted, though they do so by neglecting or abandoning other items in the sequence. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Does learning the Qur'an improve memory capacity? Practical and theoretical implications.

Our understanding of human memory has gained greatly from the study of individuals with impaired memory but rather less from outstandingly high levels of memory performance. Exceptions include the case of London taxi drivers whose extensive route learning results in modification of their hippocampus. Our study involves a group whose extensive verbal learning potentially provides a similar natural experiment. The Muslim faith encourages followers to memorise the whole of the Qur'an, some 77,449 words in its classic Arabic form. Successful memorisers are known as "Hafiz". We tested 10 Hafiz, 12 background-matched Muslim controls and 10 non-Muslim participants, on their detailed knowledge of the Qur'an and on their performance on standard measures of verbal and visuospatial learning. We found no differences between the three groups in their capacity to memorise verbal or visuospatial material and hence no evidence of generalisation of learning capacity in the Hafiz group. More surprisingly, however, half of the Hafiz group did not understand Arabic but were equivalent in Qur'anic memory to those who did. Given the importance that meaning is typically assumed to play in long-term memory, this was unexpected. We discuss the practical and theoretical implications of these results for verbal memory and long-term learning.

Unimodal and crossmodal working memory binding is not differentially affected by age or Alzheimer's disease.

Working Memory Binding (WMB) entails the integration of multiple sources of information to form and temporarily store unique representations. Information can be processed through either one (i.e., Unimodal WMB) or separate sensory modalities (i.e., Crossmodal WMB). OBJECTIVE: In this study, we investigated whether Crossmodal WMB is differentially affected by normal or pathological aging compared to Unimodal WMB. METHOD: Experiment 1: 26 older and 26 younger adults recalled the target feature matching the test probe to complete a previously displayed color-shape binding (visually presented in the Unimodal condition; auditorily and visually presented in the Crossmodal condition). Experiment 2: 35 older and 35 younger adults undertook the same paradigm while carrying out articulatory suppression to limit verbal recoding. Experiment 3: 24 Alzheimer's disease (AD) patients and two groups of 24 healthy matched controls (tested respectively with the same and an increased memory load compared to the patients) were recruited to perform a similar task. RESULTS: Results show no age-related additional cost in Crossmodal WMB in respect to Unimodal WMB. AD patients had poor attainment in both WMB tasks regardless of specific binding condition. CONCLUSION: These findings provide evidence identifying WMB per se to be impaired in AD, regardless of the type of to-be-bound material. This supports the view that WMB is a suitable cognitive marker for AD. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Forgetting in Alzheimer's disease: Is it fast? Is it affected by repeated retrieval?

OBJECTIVES: Whether people with Alzheimer's Disease present with accelerated long term forgetting compared to healthy controls is still debated. Typically, accelerated long term forgetting implies testing the same participants repeatedly over several delays. This testing method raises the issue of confounding repetition effects with forgetting rates. We used a novel procedure to disentangle the two effects. METHODS: Four short stories were presented during an initial in-person assessment of 40 patients with Alzheimer's Disease and 42 age-matched healthy controls. Our aim was for participants to reach a score of 70% correct (9 out of 13 questions) at encoding. If this criterion was not achieved after the first trial, the four stories were presented again (in a different order); participants took the 1 min filler task again and were then retested. We repeated this process until participants reached the 70% criterion or to a maximum of four trials. Cued recall memory tests were completed during follow-up telephone call(s) at different delay intervals. Study material was presented only at encoding, then probed with different question sets on all other delays. Each question set tested different sub-parts of the material. The experiment employed a mixed design. Participants were randomly allocated to either a condition without retrieval practice or a condition with retrieval practice. Participants in the condition without retrieval practice were only tested at two delays: post encoding filled delay and at one month. Participants in the condition with retrieval practice were tested at four delays: post encoding filled delay, one day, one week and one month. Our methodological design allowed us to separate the effects of retesting from the effects of delay. RESULTS: Alzheimer's Disease patients showed a significant encoding deficit reflected in the higher number of trials required to reach criterion. Using Linear Mixed Models, we found no group by delay interactions between the post encoding filled delay retrieval and one month delays, with Alzheimer's Disease groups having a similar decline in performance to healthy controls, irrespective of testing condition. Significant condition by delay interactions were found for both groups (Alzheimer's Disease and healthy controls), with better performance at one month in the condition with retrieval practice. CONCLUSIONS: Our data showed that Alzheimer's Disease is not characterised by accelerated long term forgetting, patients in our sample forgot at the same rate as healthy controls. Given the additional trials required by Alzheimer's patients to reach the 70% correct criterion, their memory impairment appears to be one of encoding. Moreover, Alzheimer's Disease patients benefited from repeated testing to the same extent as healthy controls. Due to our methodological design, we were also able to show that performance improved under repeated testing conditions, even with partial testing (sampling different features from each narrative on every test session/delay) in both healthy controls and Alzheimer's Disease.

Attention and binding in visual working memory: Two forms of attention and two kinds of buffer storage.

We review our research on the episodic buffer in the multicomponent model of working memory (Baddeley, 2000), making explicit the influence of Anne Treisman's work on the way our research has developed. The crucial linking theme concerns binding, whereby the individual features of an episode are combined as integrated representations. We summarize a series of experiments on visual working memory that investigated the retention of feature bindings and individual features. The effects of cognitive load, perceptual distraction, prioritization, serial position, and their interactions form a coherent pattern. We interpret our findings as demonstrating contrasting roles of externally driven and internally driven attentional processes, as well as a distinction between visual buffer storage and the focus of attention. Our account has strong links with Treisman's concept of focused attention and aligns with a number of contemporary approaches to visual working memory.

The problem of detecting long-term forgetting: Evidence from the Crimes Test and the Four Doors Test.

While most individuals who have problems acquiring new information forget at a normal rate, there have been reports of patients who show much more rapid forgetting, particularly comprising a subsample of patients with temporal lobe epilepsy. Currently available tests are generally not designed to test this since it requires multiple different tests of the same material. We describe two tests that aim to fill this gap, one verbal, the Crimes Test, the other visual, the Four Doors Test. Each test involves four scenes comprising five features. In each case, this allows four tests of 20 different questions to be produced and used at four different delays. Two experiments were run, each comprising a multi-test condition in which immediate testing was followed by retesting after 24 h, one week and one month, and a second condition involving a single test after one month. Both the visual and verbal tests showed clear evidence of forgetting in the single test condition, together with little evidence of forgetting in the multi-test conditions. We suggest that the testing of individual features encourages participants to remember the whole episode which then acts as a further reminder. Further research is needed to decide whether this serendipitous lack of forgetting in healthy individuals (decelerated long-term forgetting) will provide an ideal test of accelerated long-term forgetting by avoiding the danger of floor effects, or whether it will simply prove to be a further complication. Theoretical implications are discussed, as well as possible ways ahead in further investigating the surprisingly neglected field of long-term forgetting.