Episodic memory and metamemory in Parkinson’s disease patients.

This study investigated episodic memory and metamemory for verbs and nouns in patients who have cognitive impairments associated with Parkinson’s disease (PD). PD patients and healthy control participants were asked to recall word pairs and provide feeling-of-knowing (FOK) judgments for the items they were unable to recall. This was followed by a 4-alternative recognition test. PD patients were impaired in both recall and recognition, compared with controls. In terms of metamemory, PD patients were less confident in their ability to recognize the unrecalled items in a future recognition test. Most important, accuracy of PD patients’ FOK judgments was not above chance and was lower than that of control participants. The PD group correctly recognized fewer verbs than nouns, but type of material (verb vs. noun) had no impact on recall or FOK judgments. In addition, contribution of executive functions to FOK accuracy was different in PD patients and controls. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Accuracy of feeling-of-knowing judgments for predicting perceptual identification and relearning.

The feeling of knowing (FOK) refers to predictions about subsequent memory performance on previously nonrecalled items. The present research explored predictive accuracy with 2 new FOK criterion tests (in addition to recognition): relearning and perceptual identification. In 2 experiments, Ss attempted to recall the answers to general information questions, then made FOK predictions for all nonrecalled answers, and finally had a criterion test to assess the accuracy of the FOK predictions. Exp I, conducted with 32 undergraduates, demonstrated that perceptual identification can be employed successfully as a criterion test for the feeling of knowing FOK. This opens a new way for metamemory research via perception. Moreover, the FOK accuracy for predicting perceptual identification was not significantly correlated with the FOK accuracy for predicting recognition, in accord with the idea that these 2 tests assess memory differently. Exp II, conducted with 77 undergraduates, demonstrated that relearning performance can also be predicted by FOK judgments. Overall results show that there is a positive relationship between the FOK and the amount of time elapsing before a memory search is terminated during recall. (76 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Are you sure you forgot? Feeling of knowing in directed forgetting.

One significant issue in metamemory is how variables increasing memorability affect metamemory. Previous research has produced inconsistent results. The effect of directed forgetting on the magnitude and accuracy of feeling-of-knowing (FOK) judgments was investigated. Participants were presented with word pairs, some to be remembered and some to be forgotten, and then were asked to recall all target words regardless of initial instructions. For unrecalled items, they were asked to give FOK judgments about performance in a future memory task: a cued stem-completion task (Experiment 1) or a recognition test (Experiment 2). This encoding manipulation increased both the memory performance and the magnitude of FOK judgments. However, no such effect on the accuracy of FOK judgments was observed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dose effects of triazolam and scopolamine on metamemory.

The present study compared the acute dose effects of the benzodiazepine triazolam and the anticholinergic scopolamine on metamemory (knowledge and awareness of one’s own memory) in a two-phase paradigm designed to assess effects on both monitoring and control components of metamemory in both semantic (general knowledge) and episodic memory (cued-recall) tasks. Placebo and 2 doses each of triazolam (0.125, 0.25 mg/70 kg, oral) and scopolamine (0.25, 0.50 mg/70 kg, subcutaneous) were administered to 80 healthy volunteers (16 per group) in a double-blind, double-dummy, independent groups design. Both triazolam and scopolamine impaired episodic memory (quantity and accuracy) but not semantic memory. Results suggested that both drugs impaired monitoring as reflected in absolute accuracy measures (impaired calibration in the direction of overconfidence) and control sensitivity (the relationship between confidence and behavior). Overall, the results did not provide evidence for differences between triazolam and scopolamine in memory or metamemory. In addition to the clinical relevance of the observed effects, this study adds to the accumulating body of cognitive psychopharmacological research illustrating the usefulness of drug-induced amnesia as a vehicle to explore memory and metamemory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The semantic and episodic subcomponents of famous person knowledge: Dissociation in healthy subjects.

Fifty-two subjects between ages 40 and 79 years were administered a questionnaire assessing their ability to recall semantic information about famous people from 4 different decades and to recollect its episodic source of acquisition together with autonoetic consciousness via the remember-know paradigm. In addition, they underwent a battery of standardized neuropsychological tests to assess episodic and semantic memory and executive functions. The analyses of age reveal differences for the episodic source score but no differences between age groups for the semantic scores within each decade. Regardless of the age of people, the analyses also show that semantic memory subcomponents of the famous person test are highly associated with each other as well as with the source component. The recall of semantic information on the famous person test relies on participants' semantic abilities, whereas the recall of its episodic source depends on their executive functions. The present findings confirm the existence of an episodic-semantic distinction in knowledge about famous people. They provide further evidence that personal source and semantic information are at once distinct and highly interactive within the framework of remote memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociating knowing and the feeling of knowing: Further evidence for the accessibility model.

Predictions derived from the accessibility model of the feeling of knowing (FOK; A. Koriat, 1993) were tested regarding the basis of FOK and the reason for its accuracy. According to the model, FOK monitors the accessibility of partial information about unrecallable targets, and its validity depends on the accuracy of that information. General knowledge questions were classified in terms of their tendency to precipitate answers in recall (accessibility, or ACC), and the proportion of such answers that were correct (output-bound accuracy, or OBA). FOK increased with increasing ACC independent of actual recognition memory, and the FOK recognition correlation varied dramatically with OBA: It was positive for high-OBA questions, but nil or negative for low-OBA questions. The results suggest that people have no privileged access to the contents of their memory over and above what they can retrieve from it. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging, episodic memory feeling-of-knowing, and frontal functioning.

Groups of normal old and young adults made episodic memory feeling-of-knowing (FOK) judgments and took 2 types of episodic memory tests (cued recall and recognition). Neuropsychological tests of executive and memory functions thought to respectively involve the frontal and medial temporal structures were also administered. Age differences were observed on the episodic memory measures and on all neuropsychological tests. Compared with young adults, older adults performed at chance level on FOK accuracy judgments. Partial correlations indicated that a composite measure of frontal functioning and FOK accuracy were closely related. Hierarchical regression analyses showed that the composite frontal functioning score accounted for a large proportion of the age-related variance in FOK accuracy. This finding supports the idea that the age-related decline in episodic memory FOK accuracy is mainly the result of executive or frontal limitations associated with aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A further examination of the time-dependent effects of oxazepam and lorazepam on implicit and explicit memory

Until recently, research indicated that all benzodiazepines impair explicit memory, while only lorazepam impairs priming. Stewart and associates provided preliminary data which indicated that both oxazepam and lorazepam may impair implicit memory, but in a time-dependent fashion. The present study was designed to replicate Stewart et al.'s findings after overcoming several limitations of the original study. Thirty subjects were administered an acute dose of lorazepam (2 mg), oxazepam (30 mg) or a placebo and were tested with an implicit (word-stem completion) test and an explicit (cued recall) test. However, subjects were only tested at 170 min post-drug (close to oxazepam's theoretical peak concentration) to rule out the possible "explicit memory contamination" explanation of the Stewart et al. implicit memory findings. Consistent with previous research, both drugs impaired explicit memory relative to placebo. Also, both lorazepam and oxazepam impaired priming performance, supporting the "time-dependence" interpretation of the Stewart et al. findings. The results also indicate that episodic memory is impaired by both benzodiazepines in a time-dependent fashion even when the research methodology used involves everyday memory demands.     

Cognitive and subjective acute dose effects of intramuscular ketamine in healthy adults.

Ketamine is a noncompetitive N-methyl-D-aspartate (NMDA) antagonist. Given the purported role of the NMDA receptor in long-term potentiation, the primary purpose of the present study was to further understand the dose-related effects of ketamine on memory. The study was also designed to provide information about the relative effects of ketamine on memory versus nonmemory effects and to more fully characterize ketamine's overall pattern and time course of effects. Single intramuscular injections of ketamine (0.2 mg/kg, 0.4 mg/kg) were administered to 18 healthy adult volunteers using a double-blind, placebo-controlled, crossover design. Word lists were used to evaluate episodic memory (free recall, recognition memory, source memory) and metamemory. Working memory, time estimation, psychomotor performance, and subjective effects were assessed repeatedly for 5 hours after drug administration. Ketamine selectively impaired encoding (as measured by free recall) while sparing retrieval, working memory while sparing attention, and digit symbol substitution task speed while sparing accuracy. Ketamine did not significantly impair recognition or source memory, metamemory, or time estimation. There were no hallucinations or increases in mystical experiences with ketamine. Memory measures were less sensitive to ketamine effects than subjective or psychomotor measures. Subjective effects lasted longer than memory and most psychomotor impairments. Ketamine produces selective, transient, dose- and time-related effects. In conjunction with previous studies of drugs with different mechanisms of actions, the observed selectivity of effects enhances the understanding of the pharmacological mechanisms underlying memory, attention, psychomotor performance, and subjective experience. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How do we know that we know? The accessibility model of the feeling of knowing

Even when Ss fail to recall a solicited target, they can provide feeling-of-knowing (FOK) judgments about its availability in memory. Most previous studies addressed the question of FOK accuracy, only a few examined how FOK itself is determined, and none asked how the processes assumed to underlie FOK also account for its accuracy. The present work examined all 3 questions within a unified model, with the aim of demystifying the FOK phenomenon. The model postulates that the computation of FOK is parasitic on the processes involved in attempting to retrieve the target, relying on the accessibility of pertinent information. It specifies the links between memory strength, accessibility of correct and incorrect information about the target, FOK judgments, and recognition memory. Evidence from 3 experiments is presented. The results challenge the view that FOK is based on a direct, privileged access to an internal monitor.     

Age differences in feeling-of-knowing and confidence judgments as a function of knowledge domain.

For two semantic knowledge domains, general and computer-related, feeling-of-knowing (FOK) and confidence level (CL) ratings and their relative accuracy were assessed in young, middle-aged, and older adults, after test difficulty was equated across age groups. Global memory self-efficacy beliefs were also assessed for each domain. As expected, greater age was associated with poorer memory self-efficacy beliefs only in the computer domain. The oldest two groups were found to be more underconfident than young adults when rating their FOK but not their CL, for computer items but not for general items. Statistical control of age differences in memory self-efficacy beliefs in the relevant domain greatly reduced this age effect on computer-related FOK ratings. This finding suggests that absolute FOK judgments are more closely related to memory self-efficacy beliefs than are CL judgments. Gamma correlations between judgments and recognition performance revealed that all age groups were equally accurate in FOK and in CL judgments, in both domains. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of semantic encoding on recognition memory in Alzheimer's disease

Within the framework of the distinction between episodic and semantic memory, it has been argued that these two memory systems are organised in a hierarchical way. The hierarchical hypothesis assumes that episodic memory is a specific subsystem of semantic memory and therefore implies that episodic memory cannot exist without semantic memory. If this hypothesis is correct, it should be expected that patients with impaired semantic memory also have impaired episodic memory. In the present study, two experiments investigated the influence of semantic encoding on recognition memory performance in a population of 20 patients with Alzheimer's disease and 18 normal controls. Both experiments assessed recognition memory for semantically-related items. In Experiment 2, but not in Experiment 1, subjects were explicitly instructed to make a semantic association between the items. Alzheimer's disease patients were impaired, compared to the normal controls, on the recognition memory performance of both experiments. The ability to make a semantic association between two items was significantly and positively correlated with the subjects' performance on the recognition tasks. A further analysis showed that patients who were impaired on the semantic association task did significantly worse on the recognition task of Experiment 2 than normal controls and patients who were unimpaired on the semantic association task. These findings are discussed in the context of memory deficits in Alzheimer's disease, and are interpreted as supporting the view that episodic memory for an item is affected by the level of semantic awareness of that same item.     

Feeling of knowing in episodic memory following moderate to severe closed-head injury.

The ability to accurately monitor one's memory is a metacognitive process that is important in everyday life. The authors examined episodic memory feeling-of-knowing (FOK) ratings in 21 moderate to severe closed-head injury (CHI) participants (more than 1 year postinjury) and 21 controls. Participants studied 36 critical cue-target word pairs. Following a brief delay, they were asked to recall the target that corresponded to a given cue. Confidence ratings were made for recalled words, and FOK judgments were made for nonrecalled words in terms of the likelihood of recognizing the target word on a subsequent recognition test. CHI participants demonstrated less accurate recall but accurate ability to judge their recall performance (retrospective memory monitoring). They also demonstrated intact FOK judgments when providing binary judgments but demonstrated difficulties making finer discriminations on an ordinal scale (prospective memory monitoring). These findings suggest that memory monitoring is not a unitary construct. It is proposed that CHI participants may display intact memory monitoring when predictions are based on familiarity assessment but not when continued probing for additional episodic information is required. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

One declarative memory system or two? The relationship between episodic and semantic memory in children with temporal lobe epilepsy.

Objective: This study explored verbal semantic and episodic memory in children with unilateral temporal lobe epilepsy to determine whether they had impairments in both or only 1 aspect of memory, and to examine relations between performance in the 2 domains. Method: Sixty-six children and adolescents (37 with seizures of left temporal lobe onset, 29 with right-sided onset) were given 4 tasks assessing different aspects of semantic memory (picture naming, fluency, knowledge of facts, knowledge of word meanings) and 2 episodic memory tasks (story recall, word list recall). Results: High rates of impairments were observed across tasks, and no differences were found related to the laterality of the seizures. Individual patient analyses showed that there was a double dissociation between the 2 aspects of memory in that some children were impaired on episodic but not semantic memory, whereas others showed intact episodic but impaired semantic memory. Conclusions: This double dissociation suggests that these 2 memory systems may develop independently in the context of temporal lobe pathology, perhaps related to differential effects of dysfunction in the lateral and mesial temporal lobe structures. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Risk factors and prevention of vascular complications in polycythemia vera

Two experiments investigated long-term verbal memory performance in groups of 20-year-old heavy (HSDs) and light social drinkers (LSDs), in the presence and absence of a pharmacological challenge (lorazepam 2 mg). In Experiment 1 (n = 13), a verbal learning task was presented visually and it was found that lorazepam significantly impaired delayed verbal recall performance in both groups. Experiment 2 (n = 14) assessed the effect of presenting the verbal learning task in the auditory compared to the visual modality. Both groups' performance on the delayed trials of the visually presented task was reduced in the lorazepam treatment. However, in the auditory presented task, lorazepam reduced 30-min delayed recall performance in the HSDs but not in the LSDs. The differential effect of lorazepam on HSDs compared to LSDs on delayed recall performance when material is presented in the auditory modality may suggest that frequent heavy social drinking results in changes in CNS functioning.     

Multiple inputs to episodic memory: Words tell another story.

Seven patients with semantic dementia were asked to recall and recognize 10-word lists of object-name vocabulary preselected as either still "known" (correct picture naming and word-picture matching) or now "unknown" (incorrect picture naming and word-picture matching) to each individual patient. The patients showed a significant advantage for known words in immediate free recall after several learning trials and also in delayed recall and recognition. The majority of errors of commission for known words were semantic, whereas phonological errors, especially blends of target words, were produced in the unknown condition. These findings support claims that (a) multiple inputs from semantic and perceptual systems support episodic memory and (b) success in verbal and nonverbal episodic memory tasks is differentially dependent on semantic and perceptual information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feeling-of-knowing in fact retrieval: further evidence for preservation in early Alzheimer's disease

The ability to retrieve and monitor factual information varying in datedness (i.e., dated vs. contemporary) was examined in healthy older adults and patients in an early phase of Alzheimer's disease (AD). Subjects were given free recall and multiple-choice recognition tests of 48 general knowledge questions. For all questions not responded to in recall, subjects made feeling-of-knowing (FOK) judgments. Results indicated dementia-related deficits in both recall and recognition, although both groups showed better recall and recognition with the dated compared with the contemporary questions. Importantly, despite deficits in fact retrieval, the AD patients showed intact monitoring of stored knowledge, as indicated by equivalent FOK accuracy for both groups. In addition, FOK accuracy was similar for the dated and the contemporary information in both groups, suggesting independence between level of general knowledge and the ability to supervise information stored in memory.     

The influence of semantic and perceptual encoding on recognition memory in Alzheimer's disease

Previous results from a population of patients with Alzheimer's disease (Dalla Barba and Goldblum, 1996) demonstrated that the ability of patients to make a semantic association between two items was significantly and positively correlated to their performance on a yes/no recognition task for the same items and that patients who were impaired on the semantic task did significantly worse on the recognition task than patients who were unimpaired on the semantic task. These findings gave support to a hierarchical model of organization of human memory in which episodic memory depends on the integrity of semantic memory. The present study further investigates the relationship between semantic memory deficits and episodic recognition memory in 15 patients with Alzheimer's disease and 15 controls, as a function of their semantic and perceptual encoding abilities and of their cognitive impairment in other domains. The results confirmed the previous findings and showed that, although patients heavily relied on perceptual analysis, this type of encoding did not enhance their recognition memory. Correlations analyses showed that some patients who were not impaired in the semantic association, but with particularly low scores on a verbal fluency task presented with a pattern, in recognition memory tasks, that suggests a possible early involvement of frontal lobes in this subgroup of patients.     

A comparison of three predictors of an individual's memory performance: The individual's feeling of knowing versus the normative feeling of knowing versus base-rate item difficulty.

Compared the memory performance predictions of 168 undergraduates with normative item-difficulty predictions and with normative feeling-of-knowing (FOK) predictions. Ss attempted to recall the answers to general-information questions, made FOK judgments on nonrecalled items, and were subsequently administered a criterion test (relearning, perceptual identification, or 1 of 2 versions of recognition). Results indicate that, for predicting an S's criterion performance, the S's own FOK predictions were intermediate between 2 kinds of normative predictions: Ss' FOK predictions were more accurate than predictions derived from normative FOK ratings but were less accurate than predictions derived from base-rate item difficulty (normative probabilities of correct recall). Subsidiary analyses showed that factors other than unreliability were responsible for the partial inaccuracy of Ss' FOK. Possible ways to improve the accuracy of an individual's FOK predictions are discussed. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory and metamemory: A study of the feeling-of-knowing phenomenon in amnesic patients.

Tested accuracy of the feeling of knowing in 2 experiments, using 8 patients with Korsakoff's syndrome (mean age 54 yrs), 8 electroconvulsive shock therapy (ECT) patients (mean age 46.5 yrs), 4 Ss (mean age 47 yrs) with other causes of amnesia, 2 alcoholic control groups (7 Ss with a mean age of 47.6 yrs and 19 Ss with a mean age of 48.5 yrs), and 18 healthy controls (mean age 49 yrs). In Exp I, feeling-of-knowing accuracy for the answers to general information questions that could not be recalled was tested. Ss were asked to rank nonrecalled questions in terms of how likely they thought they would be to recognize the answers and were then given a recognition test for these items. Only Korsakoff's syndrome Ss were impaired in making feeling-of-knowing predictions. The other amnesic Ss were as accurate as control Ss in their feeling-of-knowing predictions. In Exp II, these findings were replicated in a sentence memory paradigm that tested newly learned information. Results show that impaired metamemory is not an obligatory feature of amnesia, because amnesia can occur without detectable metamemory deficits. The impaired metamemory exhibited by patients with Korsakoff's syndrome reflects a cognitive impairment that is not typically observed in other forms of amnesia. (50 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)