Dissociative effect of massed repetition on implicit and explicit measures of memory.

Ss saw or heard words presented once, or repeated 4 or 16 times in massed fashion, and then received an implicit or explicit memory test. Massed repetition did not increase priming on word fragment completion beyond that obtained from a single presentation but did enhance performance on various explicit tests (free recall, recognition, question cued recall, and word fragment cued recall) and an implicit general knowledge test. Modality of presentation affected implicit and explicit word fragment cued tests but did not affect performance on any of the other tests. Levels of processing affected performance on implicit and explicit question cued tests. These results are consistent with a transfer appropriate processing account of dissociations among memory measures and imply that massed repetition promotes conceptual processing but does not entail a repetition of perceptual-based processes responsible for priming on word fragment completion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prior knowledge: The effects of natural category size on memory for implicitly encoded concepts.

Studying a familiar word activates its associates, and these associates affect the likelihood of recalling the studied word in a cued recall task. These experiments examined variables that normally affect memory for the studied word to determine if they have similar effects on memory for the word's associates. Memory for associates was tested by cued recall (Experiments 1–3) or by recognition (Experiments 4–5), with the number and strength of the associates varied in all experiments. In different experiments, test instructions (direct–indirect), distractor tasks, lag, and amount of practice were manipulated. Provided that subjects were not distracted prior to test, the probability of recalling associates of the studied word decreased with the number of associates activated and with their strength under all conditions. The strength of the associates but not their number affected recognition. In general, variables that affected recall and recognition of studied words had parallel effects on their associates. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Encoding context and retrieval conditions as determinants of the effects of natural category size.

Studying a familiar word activates its associates in long-term memory. In the present experiments we manipulated the number of associates activated by words studied in the presence of unrelated context words, meaningfully related context words, or in the absence of modifying context words. Memory was tested by either cued or free recall. The results showed that the number of directly activated associates can facilitate, have no effect, or disrupt recall for studied words. The direction and magnitude of the effects of number of activated associates is shown to be determined by the encoding/retrieval context. Implications for the distinction between episodic and semantic memory are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adult age differences in implicit and explicit memory: Time course and encoding effects.

Young and older adults were tested at three delays on word-stem completion or cued recall following semantic or structural word judgments. Identical three-letter stems were present at retrieval for both implicit (completion) and explicit (cued recall) tasks; only the intention to recall list words differed. The young adults outperformed the older adults on both implicit and explicit task at all test delays. Under some conditions, the older but not the young adults performed more poorly on cued recall than on stem completion, suggesting a possible failure to use implicitly available information to support explicit remembering. These results suggest that some forms of implicit memory decline with normal aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Event-related potentials of verbal encoding into episodic memory: dissociation between the effects of subsequent memory performance and distinctiveness

Episodic memory encoding and distinctiveness detection were examined using event-related potentials (ERP) in a single-trial word list learning paradigm with free recall following distraction. To manipulate distinctiveness, encoding of high- and very low-frequency words was contrasted. Amplitudes of the N400 and late positive component (LPC) were larger for low- than for high-frequency words, and ERPs were more positive for subsequently recalled than not recalled words. This subsequent memory effect was dissociated from the correlates of distinctiveness by polarity for the N400 and by time course for the LPC and dissociable into two effects. The data suggest that the first subsequent memory effect, which occurred for both word categories, is more directly related to episodic memory formation, whereas the second effect, which occurred for high-frequency words only, is related to processes influencing episodic encoding success indirectly.     

Concreteness of relational effects on recall of adjective–noun pairs.

Studied the effects of concreteness and relatedness of adjective–noun pairs on free recall, cued recall, and memory integration. The authors report on 2 experiments in which Ss read phrases or sentences containing adjective–noun pairs that vary in rated concreteness and intrapair relatedness. In Exp 1 normative ratings on imagery and relatedness were provided by 23 graduate and 20 undergraduate students. 64 undergraduates participated in the memory experiment. Exp 2 extended Exp 1 by using complete sentences rather than adjective–noun word pairs. 72 undergraduates volunteered to participate in the memory experiment and a separate group of 14 volunteered to participate in a sentence rating task. Consistent with predictions from dual coding theory and prior results with noun–noun pairs, both experiments showed that the effects of concreteness were strong and independent of relatedness in free recall and cued recall. The 2 attributes also had independent (additive) effects on integrative memory as measured by conditionalized free recall of pairs. Integration as measured by the increment from free to cued recall occurred consistently only when pairs were high in both concreteness and relatedness. Relatedness, adjective imagery, and noun imagery ratings, along with word frequencies for adjectives and nouns, and sentences with relatedness ratings are appended. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Arbitrary associations in animals: What can paired associate recall in rats tell us about the neural basis of episodic memory? Theoretical comment on Kesner, Hunsaker, & Warthen (2008).

Detailed memories for unique episodes from an individual's past can be triggered, often effortlessly, when that individual is exposed to a stimulus that was present during the original event. The aim of Kesner et al. (see record 2008-17011-003) is to understand the neural basis of memory encoding that supports this cued recall of episodic memories. Kesner and colleagues make novel use of an object-place paired-associate task for rats to provide evidence for a critical role of dorsal CA3 in certain aspects of episodic memory encoding. Using one-trial cued recall versions of the task they show that when rats are cued with an object stimulus, they can be trained to revisit the location in which the object appeared previously. Conversely, when rats are cued with a location, they can learn to choose the object with which it was associated. Rats with dorsal CA3 lesions are severely impaired at these tasks. These data are consistent with the theory that the autoassociative network in CA3 supports the rapid formation of novel associations and may allow pattern completion--the phenomenom whereby a subset of the cues present at an encoding event triggers recall of the whole event. Although flexible recall of arbitrary associations is not fully demonstrated, the study contributes 2 novel behavioral tasks to the previously limited repertoire for studying paired associate recall in rats. It also builds on previous data to specify the role of the hippocampal CA3 subregion in cued recall--a critical aspect of episodic memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The dynamics of memory retrieval in older adulthood.

One of the most robust findings in cognitive aging is that of a significant decline in self-initiated recall from episodic memory. In laboratory studies this deficit can be seen in significant age differences in word-list free recall. In this article, the authors focus on free recall of categorized word lists where one observes "response bursting" in the form of a rapid output of within-category items with longer delays between categories. Age differences appear primarily in between category latencies, results that are consistent with a relative sparing of semantic memory combined with an age-deficit in episodic retrieval. When adjusted for differences in overall mnemonic ability, it is demonstrated that the relationship between organization and learning remains invariant with normal aging. The authors argue that the locus of the age deficit in free recall lies at the level of temporal coding of items and the use of temporal associations to guide recall. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interidentity amnesia for neutral, episodic information in dissociative identity disorder.

Interidentity amnesia is considered a hallmark of dissociative identity disorder (DID) in clinical practice. In this study, objective methods of testing episodic memory transfer between identities were used. Tests of both recall (interference paradigm) and recognition were used. A sample of 31 DID patients was included. Additionally, 50 control subjects participated, half functioning as normal controls and the other half simulating interidentity amnesia. Twenty-one patients subjectively reported complete one-way amnesia for the learning episode. However, objectively, neither recall nor recognition scores of patients were different from those of normal controls. It is suggested that clinical models of amnesia in DID may be specified to exclude episodic memory impairments for emotionally neutral material. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual memory change after anterior temporal lobectomy: a base rate analysis using regression-based outcome methodology

PURPOSE: To characterize patterns of base rate change on measures of verbal and visual memory after anterior temporal lobectomy (ATL) using a newly developed regression-based outcome methodology that accounts for effects of practice and regression towards the mean, and to comment on the predictive utility of baseline memory measures on postoperative memory outcome. METHODS: Memory change was operationalized using regression-based change norms in a group of left (n = 53) and right (n = 48) ATL patients. All patients were administered tests of episodic verbal (prose recall, list learning) and visual (figure reproduction) memory, and semantic memory before and after ATL. RESULTS: ATL patients displayed a wide range of memory outcome across verbal and visual memory domains. Significant performance declines were noted for 25-50% of left ATL patients on verbal semantic and episodic memory tasks, while one-third of right ATL patients displayed significant declines in immediate and delayed episodic prose recall. Significant performance improvement was noted in an additional one-third of right ATL patients on delayed prose recall. Base rate change was similar between the two ATL groups across immediate and delayed visual memory. Approximately one-fourth of all patients displayed clinically meaningful losses on the visual memory task following surgery. Robust relationships between preoperative memory measures and nonstandardized change scores were attenuated or reversed using standardized memory outcome techniques. CONCLUSIONS: Our results demonstrated substantial group variability in memory outcome for ATL patients. These results extend previous research by incorporating known effects of practice and regression to the mean when addressing meaningful neuropsychological change following epilepsy surgery. Our findings also suggest that future neuropsychological outcome studies should take steps towards controlling for regression-to-the-mean before drawing predictive conclusions.     

Retrieval constraints on associative elaborations.

This research investigated the role of associative elaborations on free- and cued-recall performance. Elaboration was manipulated by having subjects pronounce an associatively related word that could be integrated into an activated episodic trace following sentence-encoding operations on the target concept. In Experiments 1 and 2, free recall was facilitated when the word was related to the sentence context of the target encoding compared to when it was related only to the target, or both the target and the context. The target-related conditions did not differ from an unrelated control condition for positive response encodings. This same pattern held for cued recall when the sentence frame context was provided as the retrieval cue (Experiment 1). However, Experiment 2 showed that if the elaborating word was provided as a cue for the target, then recall was highest when it was related to both the target and its context or only to the target. The results are discussed in terms of retrieval constraints on associative elaborations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influences of intentional and unintentional forgetting on false memories.

In 2 experiments, we examined the interplay of 2 types of memory errors: forgetting and false memory--errors of omission and commission, respectively. We examined the effects of 2 manipulations known to inhibit retrieval of studied words--directed forgetting and part--list cuing--on the false recall of an unstudied "critical" word following study of its 15 strongest associates. Participants cued to forget the 1st of 2nd studied lists before studying the 2nd recalled fewer List 1 words but intruded the missing critical word more often than did participants cued to remember both lists. By contrast, providing some studied words as cues during recall reduced both recall of the remaining studied words and intrusions of the critical word. The results suggest that forgetting can increase or decrease false memories, depending on whether such forgetting reflects impaired access to an entire episode or retrieval competition among elements of an episode. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective use of the Eight-Word subtest in psychogeriatrics

Performance on the Amsterdam Dementia Screening Test (ADS) and the Expanded Mental Control Test (EMCT) was examined in a consecutive sample of 204 attendants of a psychogeriatric day care department. The ADS has six subtests: picture recognition, orientation, drawing alternating sequences, category fluency, copying geometric figures, and free recall with immediate yes-no recognition of eight words. As was determined by logistic regression analysis, attentional control (EMCT), category fluency and picture recognition scores were significant predictors of verbal free recall. Recognition memory for pictures and a short orientation questionnaire (month, year, place) predicted word recognition performance. In 97% of the subjects with poor scores on EMCT and category fluency, an equally poor free recall performance was found. In those cases the incremental diagnostic value of the free recall test is doubtful. Since word recall and word recognition were conceptually related to working memory and episodic memory respectively, the two components of the verbal learning test allow detection of differential impairments of these memory systems.     

Is priming in fragment completion based on a "traceless" memory system?

Four experiments investigated the relation between successive tests of primed fragment completion with the use of the same or different fragments on successive tests. The results were contrasted with successive tests of fragment cued recall using identical study/test stimuli and differing from the fragment completion task only in terms of instructions. Performance on successive tests of primed fragment completion was dependent if the same fragments were represented on both tests. There was no reliable dependence when different fragments were used on the two fragment completion tests. In contrast, when fragment cued recall instructions were given, successive tests with both same and different fragments yielded clear dependence. The results are interpreted as evidence that performance in the fragment completion task does not depend upon a specific cognitive unit or memory trace, whereas in episodic cued recall it does. This suggestion is elaborated in terms of an integration of the transfer-appropriate procedural approach with the idea of a traceless memory system that supports priming in tasks such as fragment completion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Investigating the structure and age invariance of episodic memory across the adult lifespan.

The structure of episodic memory was investigated by assessing different modalities of material (verbal, figural, and spatial) and different types of tests (recall, cued recall, and recognition). A 3-factor model that distinguished among modalities of material was found to be the best representation of memory and the verbal, figural, and spatial memory factors exhibiting construct validity. This 3-factor modality of material model also demonstrated configural, metric, and structural age invariance across a sample of adults (N = 327) between the ages of 18 and 94. There was evidence that latent constructs corresponding to recall, cued recall, and recognition could be distinguished from one another within the verbal domain but not within the figural and spatial domains. A mediation model examining the retrieval constructs was examined within the verbal domain, and there were unique age-related influences on cued recall and recall performance. This result is consistent with findings that increased age is associated with increased difficulty in retrieving information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Remote semantic memory in patients with Korsakoff's syndrome and herpes encephalitis.

Performance of patients with Korsakoff's syndrome and herpes encephalitis was compared on a retrograde amnesia (RA) test, asking subjects to recall and recognize the definitions of words that had come into the language at different time periods. Performance was also compared on a related test in which participants were asked to produce the words to definitions they were given in free recall and cued recall versions. It was hypothesized that, if the temporal gradient in remote memory results from a shift of information from episodic to semantic memory, then there should be a temporal gradient on these tasks, possibly steeper (i.e., greater relative sparing of early memories) in the patients in the Korsakoff group than in the herpes encephalitis group, who have widespread temporal lobe damage. Furthermore, in comparing semantic and episodic remote memory tests, consolidation theory would predict uniform temporal gradients across such tasks, whereas multiple trace theory would predict a differential pattern. The results showed that patients with Korsakoff's syndrome and patients with herpes encephalitis were significantly impaired across all time periods on the vocabulary tests, with only minimal evidence of temporal gradients, relative to healthy participants, and there was no evidence of a differential pattern of impairment between the two patient groups. Comparison with performance on measures of episodic retrograde amnesia, in which there was a differential pattern of temporal gradient, suggests that the relative preservation of early episodic remote memories in patients with Korsakoff's syndrome does not result from an episodic-to-semantic shift in the quality with which memories are stored. These findings are discussed in relation to existing theories of RA and to the patients' underlying patterns of neuropathology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neural correlates of cued recall with and without retrieval of source memory

A source memory procedure was used to investigate whether event-related potentials (ERPs) reflect the retrieval of episodic information (recollection) on tests of word-stem cued recall. 'Cued recall ERP effects' for recalled items were found to differ only in their magnitudes, and not their scalp distributions, according to the accuracy of source memory. This finding strongly supports the hypothesis that cued recall ERP effects reflect quantitative variation in the amount or quality of information which can be retrieved about recently experienced events. Topographic analyses also revealed that the distribution of the cued recall ERP effects changed over time, reflecting the activity of at least two temporally and neuroanatomically dissociable neural populations contributing to recollection on this task.     

Different ways to cue a coherent memory system: A theory for episodic, semantic, and procedural tasks.

An associative theory of human memory is proposed, which serves as a counterexample to claims that disassociations between episodic, semantic, and procedural memory tasks necessitate separate memory systems. The theory is based on task analyses of matching (recognition and familiarity judgments), retrieval (cued recall with list associates, extralist associates, and part-word cues), and production (producing the first word that comes to mind). These analyses are then embedded in a distributed storage model, and it is shown how proactive interference from old memories can be largely eliminated by combining cue strengths interactively at study and test. A distinction between modality-specific and more central, modality independent, memory codes is also introduced. The model is extended to the performance of amnesic patients, and the general approach to human memory is then evaluated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention and retrieval from long-term memory.

Conducted 9 experiments with 152 female volunteers (mean age 44.4 yrs) to investigate the disrupting effect of a secondary task on retrieval from long-term memory. Exps I–V studied the influence of concurrent card sorting or digit span on free recall or paired-associate learning of word lists. Exp VI explored recall probability using a recognition paradigm in which accuracy and latency could be measured simultaneously. Exp VII explored the latency effect with a semantic memory paradigm, and Exp VIII required Ss to make semantic category judgments while retaining sequences of 6 digits. Exp IX examined the effect of concurrent digital load on the rate of generating items from semantic categories. Overall findings reveal that a demanding concurrent task did not reduce the probability of retrieving an item from semantic or episodic memory. However, concurrent load during learning substantially effected recall performance. A concurrent task during retrieval did not have a clear effect on latency. The contrast between the pattern shown by errors and by that shown by latencies suggests that attempts to estimate the attentional demands of any task should be interpreted with considerable caution when based on a single measure, such as performance errors, performance latency, or a response to a probe RT signal. (38 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting episodic memory performance in dementia: Is severity all there is?

Whether individual differences in demographic, psychometric, and biological domains can predict episodic memory in dementia was investigated. Mildly to moderately demented very old persons performed episodic memory tasks (free recall and recognition of slowly and rapidly presented random words, free and cued recall of organizable words, and recognition of dated and contemporary famous faces). A factor analysis of the memory measures yielded 2 factors, 1 indexing recall and 1 recognition. Controlling for severity of dementia, only 2 predictors contributed to performance: (a) Block Design (a marker of fluid intelligence) was positively related to recall, and (b) age was negatively related to recognition. Although these results are similar to data reported on predictors of episodic memory in normal aging, (a) the number of predictive variables appears to be reduced in dementia, and (b) age seems to affect recall and recognition differentially in normal aging and dementia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)