Directed forgetting of autobiographical memory in mild Alzheimer's disease

Using the autobiographical directed forgetting method (Barnier et al., 2007), the present paper addressed the intentional inhibitory processes of episodic and semantic autobiographical memory in Alzheimer's disease (AD). Mild AD patients and healthy elderly people were instructed to either forget or to continue remembering previously generated autobiographical events. In a later recall test they were asked to reconstruct the early-generated memories regardless of the forget/remember instruction. Autobiographical reconstruction was further distributed into episodic and semantic memories. Results showed no forget instruction effect on episodic or semantic autobiographical recall with AD patients, whereas healthy elderly people were able to inhibit only episodic autobiographical memories. The findings suggest an impairment of the intentional inhibitory processes in autobiographical memory with AD and a relative preservation of these mechanisms with normal ageing. They also demonstrate an earlier decline in the intentional inhibitory processes compared to the autobiographical deterioration in AD.     

Directed forgetting of autobiographical events

Two diary experiments demonstrated directed forgetting (DF) of autobiographical events, previously observed only for less complex memory items. Using a 2-week diary paradigm, we compared recall between a group of participants who were directed to forget Week 1 memories (forget group) and a group who did not receive a forget instruction (remember group). In Experiment 1, the forget group remembered fewer items from Week 1 than did the remember group. The effect was observed for negative and positive valence events, as well as for high and low emotional intensity events. The effect was replicated in Experiment 2 despite a memorable holiday (Valentine's Day) that occurred during the manipulation week. Forget participants remembered fewer low emotional intensity items in Experiment 2. We conclude that intentional forgetting is a plausible explanation for the loss of some autobiographical memories.     

Directed forgetting of recently recalled autobiographical memories

In 6 experiments, the authors investigated list-method directed forgetting of recently recalled autobiographical memories. Reliable directed forgetting effects were observed across all experiments. In 4 experiments, the authors examined the impact of memory valence on directed forgetting. The forget instruction impaired recall of negative, positive, and neutral memories equally, although overall, participants recalled fewer unemotional memories than emotional memories. The preexisting organization of memories enhanced the directed forgetting effect, and a release from forgetting occurred only when the forgotten memories were directly cued. The authors discuss the roles of emotion, retrieval dynamics, and organization in these effects and suggest that the directed forgetting of recently recalled autobiographical memories may reflect the inhibition of recently formed memories of remembering, that is, episodic inhibition. The authors consider the implications of these findings for the control of autobiographical remembering in everyday life.     

Directed search through autobiographical memory

Two experiments were designed to study retrieval from a well-ordered set of overlearned information in long-term autobiographical memory. In Experiment 1, each of 161 university students was asked to recall the name of one teacher from each of the 12 preuniversity school years. Recall was cued in forward (Grades 1-12), backward (Grades 12-1), or random order. Backward-ordered search proved most efficient: Fewer students failed to complete the task :in that search order, and those who did complete the task were faster than the successful students in the other search orders. Experiment 2 was similar to Experiment 1, except that the 148 students tested were asked to “think aloud” as they attempted recall. From the resulting protocols, 25 categories of verbal reports were identified, including four that reflected retrieval strategies. Omission errors (failures to recall teachers’ names) and, with one exception, frequencies of verbal reports decreased as recency increased. Taken together, the results of both experiments show that the recall of one item can indirectly aid the recall of contiguous items and that the probability of recalling an item from autobiographical memory is primarily a function of recency.     

Memory of myself: autobiographical memory and identity in Alzheimer's disease

A number of theories posit a relationship between autobiographical memory and identity. To test this we assessed the status of autobiographical memory and identity in 20 individuals with Alzheimer's disease (AD) and 20 age-matched controls, and investigated whether degree of autobiographical memory impairment was associated with changes in identity. Two tests of autobiographical memory (Autobiographical Memory Interview, autobiographical fluency) and two measures of identity (Twenty Statements Test, identity items of the Tennessee Self Concept Scale) were administered. AD participants exhibited significant impairments on both memory tests, and changes in the strength, quality, and direction of identity relative to controls. Impairments of some components of autobiographical memory, particularly autobiographical memory for childhood and early adulthood, were related to changes in the strength and quality of identity. These findings support the critical role of early adulthood autobiographical memories (16-25 years) in identity, and suggest autobiographical memory loss affects identity.     

Directed forgetting in working memory: age-related differences

This study explored the effects of ageing on working memory by means of the directed forgetting procedure designed by Reed (1970). Memory for a letter trigram was compared in conditions where it was either presented alone (single-item), or followed by a second trigram to be recalled (interference), or followed by a second trigram to be forgotten (directed forgetting). The results clearly indicated that elderly participants inhibited the no-longer-relevant information less efficiently (recall in the single-item condition - recall in the directed forgetting condition), as predicted by the model of Hasher and Zacks (1988). However, the results also demonstrated that sensitivity to interference (recall in the single-item condition - recall in the interference condition) increased in the condition in which no inhibition was directly required.     

Directed forgetting and directed remembering in visual working memory

A defining characteristic of visual working memory is its limited capacity. This means that it is crucial to maintain only the most relevant information in visual working memory. However, empirical research is mixed as to whether it is possible to selectively maintain a subset of the information previously encoded into visual working memory. Here we examined the ability of participants to use cues to either forget or remember a subset of the information already stored in visual working memory. In Experiment 1, participants were cued to either forget or remember 1 of 2 groups of colored squares during a change-detection task. We found that both types of cues aided performance in the visual working memory task but that observers benefited more from a cue to remember than a cue to forget a subset of the objects. In Experiment 2, we show that the previous findings, which indicated that directed-forgetting cues are ineffective, were likely due to the presence of invalid cues that appeared to cause observers to disregard such cues as unreliable. In Experiment 3, we recorded event-related potentials and show that an electrophysiological index of focused maintenance is elicited by cues that indicate which subset of information in visual working memory needs to be remembered, ruling out alternative explanations of the behavioral effects of retention-interval cues. The present findings demonstrate that observers can focus maintenance mechanisms on specific objects in visual working memory based on cues indicating future task relevance. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

The use of a wearable camera improves autobiographical memory in patients with Alzheimer's disease

Despite the marked impairment of recent episodic memories in Alzheimer's disease, there have been few attempts to rehabilitate these deficits. We used a novel external memory aid to promote recall of episodic memories in patients with mild to moderate Alzheimer's disease. SenseCam, a small wearable camera, recorded significant events in the lives of six Alzheimer's disease patients. Every two days for two weeks each patient's memory for an event was assessed, followed by a structured review of the SenseCam images. Longer-term recall was tested one and three months later. A written diary control condition followed the same procedure. Across 40 events the SenseCam review method resulted in significantly more details of an event being recalled over two weeks than the written diary method in five out of the six patients. At three months post event, four out of five patients (one had dropped out) recalled significantly more details of events in the SenseCam condition while the other patient showed no significant difference. Viewing SenseCam images of personally experienced events may significantly improve autobiographical memory in patients with even moderate Alzheimer's disease.     

Directed forgetting in the list method affects recognition memory for source

The effects of list-method directed forgetting on recognition memory were explored. In Experiment 1 (N = 40), observers were instructed to remember words and their type-cases; in Experiment 2 (N = 80), the instruction was to remember words and their colours. Two lists of 10 words were presented; after the first list, half of the observers (forget) were instructed to forget that list, and the other half (remember) were not given the forget instruction. Recognition of items (words) as well as source (encoding list + case/colour) was measured for forget and remember observers. The forget instruction affected case/colour memory more consistently than item and list memory; a multinomial analysis indicated that source information was affected by the forget instructions. The results indicated that recognition of source information may be a more sensitive indicator of forgetting than recognition of items.     

Directed forgetting in the list method affects recognition memory for source

The effects of list-method directed forgetting on recognition memory were explored. In Experiment 1 (N = 40), observers were instructed to remember words and their type-cases; in Experiment 2 (N = 80), the instruction was to remember words and their colours. Two lists of 10 words were presented; after the first list, half of the observers (forget) were instructed to forget that list, and the other half (remember) were not given the forget instruction. Recognition of items (words) as well as source (encoding list + case/colour) was measured for forget and remember observers. The forget instruction affected case/colour memory more consistently than item and list memory; a multinomial analysis indicated that source information was affected by the forget instructions. The results indicated that recognition of source information may be a more sensitive indicator of forgetting than recognition of items.     

Evaluation of prospective memory training for individuals with mild Alzheimer's disease

Prospective memory (PM) refers to the timely execution of a previously formed intention. PM deficits are one of the earliest measurable deficits in Alzheimer's disease (AD; Huppert & Beardsall, 1993) and yet, there has been little systematic research devoted to identifying ways in which these deficits can be compensated for or minimized. In this pilot study, individuals with mild AD participated in a new training program aimed at improving PM performance on an experimental PM task. PM training consisted of errorless learning and spaced retrieval techniques taught in six sessions in subjects' homes. Results showed that compared to untrained AD controls. AD patients who received PM training performed a PM task successfully across 7 weeks posttreatment (over 90% accuracy; controls 16-33% accuracy).     

Cognitive control of familiarity: Directed forgetting reduces proactive interference in working memory

Proactive interference (PI) occurs when previously learned information interferes with new learning. In a working memory task, PI induces longer response times and more errors to recent negative probes than to new probes, presumably because the recent probe’s familiarity invites a “yes” response. Warnings, longer intertrial intervals, and the increased contextual salience of the probes can reduce but not eliminate PI, suggesting that cognitive control over PI is limited. Here we tested whether control exerted in the form of intentional forgetting performed during working memory can reduce the magnitude of PI. In two experiments, participants performed a working memory task with directed-forgetting instructions and the occasional presentation of recent probes. Surprise long-term memory testing indicated better memory for to-be-remembered than for to-be-forgotten items, documenting the classic directed-forgetting effect. Critically, in working memory, PI was virtually eliminated for recent probes from prior to-be-forgotten lists, as compared to recent probes from prior to-be-remembered lists. Thus cognitive control, when executed via directed forgetting, can reduce the adverse and otherwise persistent interference from familiarity, an effect that we attribute to attenuated memory representations of the to-be-forgotten items.     

Influence of motoric encoding on forgetting function of memory for action sentences in patients with Alzheimer's disease

This study assessed whether verbal encoding and motoric encoding have different effects on the forgetting function for action sentences of patients with Alzheimer's disease. Subjects were 13 healthy elderly adults and 10 patients diagnosed with Alzheimer's disease. Three tasks were used: verbal tasks, subject-performed tasks, observed tasks. On the verbal tasks, subjects only heard the action sentences as read to them. On the subject-performed tasks, subjects heard, then performed each action sentence. On the observed tasks, subjects heard the action sentences read while observing the object mentioned in each action sentence. After presentation of each task, subjects conducted immediate and 30-min. delayed recall tests, and then a recognition test. Analysis indicated recall performance for subject-performed tasks was significantly better than that for verbal tasks and observed tasks at both immediate and delayed recall in each group. On the recognition test, carrying out the action had no effect, but for both groups recognition was enhanced by observing the object. Elderly adults performed significantly better than patients on all tasks of recall and recognition. However, the results indicate that patients with Alzheimer's disease can use multimodal resources from motoric encoding even if time passes.     

The involuntary nature of music-evoked autobiographical memories in Alzheimer's disease

The main objective of this paper was to examine the involuntary nature of music-evoked autobiographical memories. For this purpose, young adults, older adults, and patients with a clinical diagnosis of probable Alzheimer's disease (AD) were asked to remember autobiographical events in two conditions: after being exposed to their own chosen music, and in silence. Compared to memories evoked in silence, memories evoked in the "Music" condition were found to be more specific, accompanied by more emotional content and impact on mood, and retrieved faster. In addition, these memories engaged less executive processes. Thus, with all these characteristics and the fact that they are activated by a perceptual cue (i.e., music), music-evoked autobiographic memories have all the features to be considered as involuntary memories. Our paper reveals several characteristics of music-evoked autobiographical memories in AD patients and offers a theoretical background for this phenomenon.     

Directed forgetting of emotional words

Emotional material may induce processing limitations affecting memory performance. In the present study, the authors investigated how the emotional content of words influences the degree to which participants can be directed to forget them. In Experiment 1, the authors found that negative-valence words were recalled better when participants were told to forget them than when they were told to remember them. This effect was only obtained when a study-list of negative words was presented after the cue to remember or forget the first list. The effect was correlated with negative mood as assessed by the PANAS. Similar results were obtained in Experiment 2, in which the induction of negative arousal by a mild stressor abolished the directed forgetting of words when the following study list was comprised of negative words. These results support the idea that directed forgetting relies on cognitive control processes that may be disrupted by negative emotion.     

Direct versus indirect tests of memory: Directed forgetting meets the generation effect

Subjects read 20 words and generated 20 others from definitions during a 40-item study phase. Production of each word was followed by an instruction to remember or to forget that word. In free recall, a direct test of memory, words that had been generated were recalled much better than words that had been read. The remember-forget instructional manipulation affected read words but not generated words. In speeded word reading, an indirect test of memory, all studied words showed priming, but read words showed more priming than generated words. Here, the effect of remember versus forget instructions appeared only for generated words. These dissociations of a direct and an indirect test indicate that two powerful encoding manipulations affect separable processes to which these tests are differentially sensitive.     

Directed forgetting in acute stress disorder

The rationale underpinning the diagnosis of acute stress disorder is that cognitive mechanisms result in avoidant processing of aversive experiences. This study investigated acutely traumatized participants with either acute stress disorder (ASD; n = 15) or no ASD (n = 14) and nontraumatized comparison participants (n = 16). Participants were administered intermixed presentations on a computer screen of positive, neutral, and trauma-related words that were followed by instructions to either remember or forget each word. On a subsequent recall test, ASD participants displayed poorer recall of to-be-forgotten trauma-related words than did non-ASD participants. Severity of psychopathology was negatively correlated with to-be-remembered positive words. These findings are consistent with the proposal that people who develop ASD display an aptitude for superior forgetting of aversive material.     

Semantic memory in Alzheimer's disease

Patients with Alzheimer's disease have been suggested to have a semantic memory impairment not present in the normal old. This article reviews the performance of Alzheimer patients on tests of various aspects of semantic memory, including word finding, knowledge of the semantic attributes, and associates of concepts, as well as their category membership. The effect that semantic context has on cognitive processes such as lexical and semantic priming and memory encoding is also reviewed. Finally, the ability of theoretical constructs such as implicit memory and automaticity to explain intertask variability in Alzheimer patients' semantic performance is discussed.     

Directed forgetting for categorised pictures: recognition memory for perceptual details versus gist

ABSTRACT

Item-based directed forgetting (DF) was tested using 2-alternative forced-choice recognition to examine the effects of forgetting instructions on memory for perceptual detail and gist of categorised pictures of scenes and objects in three experiments. When the distractor is from the same category as the target (exemplar test condition), discrimination must be based on memory for perceptual details, whereas recognition can be based on gist or general category information when the distractor is from a novel category (novel test condition). Recognition accuracy was greater for Remember-cued than Forget-cued pictures when discrimination must be based on perceptual details in the exemplar test condition but not when discrimination could be based on gist in the novel test condition. Accuracy in scene and object recognition is greater for gist than for perceptual details, and DF instructions serve to reduce recognition memory based on perceptual details.     

Directed forgetting of a single item

In two experiments, we investigated directed forgetting of a single item. We presented participants with two phone numbers to remember and instructed half of the participants to forget the first phone number. The first number was either learned on a single trial (Experiment 1) or on three trials (Experiment 2). In Experiment 1, there was evidence of directed forgetting as a result of differential encoding; the forget instruction affected recall and recognition for both phone numbers. In Experiment 2, the evidence favored differential rehearsal because the forget instruction affected recall but not recognition. These results indicate that instructions to forget can affect memory of single items.