On the relationship between recall and recognition memory.

The relationship between recall and recognition has been a central topic for the study of memory. A test of alternative views about recall and recognition was arranged by studying amnesic patients. In amnesia, damage has occurred to a brain system important for declarative (conscious) memory, but skill learning, priming, and other forms of nonconscious memory are intact. Recall and recognition were found to be proportionately impaired in amnesic patients, and confidence ratings for the recognition judgments were commensurate with the level of impaired performance. The results are contrary to views that either recognition memory or associated confidence judgments are ordinarily supported significantly by nonconscious memory. The results favor the view that recall and recognition are related functions of declarative memory and equivalently dependent on the brain system damaged in amnesia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual thresholds and priming in amnesia.

The widely accepted idea that perceptual priming is intact in amnesia was challenged recently by the suggestion that perceptual identification (PID) thresholds are elevated in amnesia and that this impairment could mask a priming deficit by artificially inflating priming scores. The authors examined the PID thresholds of amnesic patients across a wide range of stimulus conditions and accuracy levels. Baseline thresholds and priming effects were fully intact for all amnesic patients except in a condition using small stimuli (1.1"?×?0.25" of visual angle). In that condition, only the patients with Korsakoff's syndrome were impaired. Accordingly, elevated perceptual thresholds are not a necessary consequence of amnesia, and normal priming in amnesia is not an artifact of threshold differences. The results support the conclusion that priming is independent of the brain structures important for declarative memory that are damaged in amnesia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is striatal dopaminergic receptor imbalance responsible for levodopa-induced dyskinesia?

Amnesic patients often exhibit spared priming effects on implicit memory tests despite poor explicit memory. In previous research, we found normal auditory priming in amnesic patients on a task in which the magnitude of priming in control subjects was independent of whether speaker's voice was same or different at study and test, and found impaired voice-specific priming on a task in which priming in control subjects is higher when speaker's voice is the same at study and test than when it is different. The present experiments provide further evidence of spared auditory priming in amnesia, demonstrate that normal priming effects are not an artifact of low levels of baseline performance, and provide suggestive evidence that amnesic patients can exhibit voice-specific priming when experimental conditions do not require them to interactively bind together word and voice information.     

A single-system account of the relationship between priming, recognition, and fluency.

A single-system computational model of priming and recognition was applied to studies that have looked at the relationship between priming, recognition, and fluency in continuous identification paradigms. The model was applied to 3 findings that have been interpreted as evidence for a multiple-systems account: (a) priming can occur for items not recognized; (b) the pattern of identification reaction times (RTs) to hits, misses, correct rejections, and false alarms can change as a function of recognition performance; and (c) fluency effects (shorter RTs to words judged old vs. judged new) and priming effects (shorter RTs to old vs. new words) can be observed in amnesic patients at levels comparable with healthy adults despite impaired or near-chance recognition. The authors' simulations suggest, contrary to previous interpretations, that these results are consistent with a single-system account. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impaired priming on the general knowledge task in amnesia.

The status of priming on the general knowledge test was examined in amnesia. Twenty amnesic and 20 control participants studied words (e.g., CHEETAH) under semantic and nonsemantic encoding conditions and attempted to answer general knowledge questions (e.g., "What is the fastest animal on earth"?) under implicit and explicit retrieval instructions. The measure of memory was how many more test questions participants answered correctly using studied than nonstudied words. Amnesic patients showed impaired memory under implicit and explicit retrieval instructions. Control participants showed equal memory under implicit and explicit retrieval instructions, a result indicating that they engaged in explicit retrieval in both instruction conditions. General-knowledge priming appears to involve explicit retrieval that depends on medial-temporal and diencephalic regions damaged in amnesia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A neuropsychological study of fact memory and source amnesia.

We investigated the ability of amnesic patients to learn new facts (e.g., Angel Falls is located in Venezuela) and also to remember where and when the facts were learned (i.e., source memory). To assess the susceptibility of fact and source memory to retrograde amnesia, patients prescribed electroconvulsive therapy were presented facts prior to the first treatment and were tested after their second treatment. All amnesic patients exhibited marked fact memory impairment. In addition, some amnesic patients exhibited source amnesia (i.e., they recalled a few facts but then could not remember where or when those facts had been learned). Source amnesia was unrelated to the severity of the memory deficit itself, because patients who exhibited source amnesia recalled as many facts as the patients who did not. These results show that the deficit in amnesia includes an impairment in acquiring and retaining new facts. Source amnesia can also occur, but it is dissociable from impaired recall and recognition and appears to reflect difficulty in remembering the specific context in which information is acquired. The findings are discussed in terms of their significance for how memory is organized. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intact and impaired conceptual memory processes in amnesia.

To examine the status of conceptual memory processes in amnesia, a conceptual memory task with implicit or explicit task instructions was given to amnesic and control groups. After studying a list of category exemplars, participants saw category labels and were asked to generate as many exemplars as possible (an implicit memory task) or to generate exemplars that had been in the prior study list (an explicit memory task). After incidental deep or shallow encoding of exemplars, amnesic patients showed normal implicit memory performance (priming), a normal levels-of-processing effect on priming, and impaired explicit memory performance. After intentional encoding of exemplars, amnesic patients showed impaired implicit and explicit memory performance. Results suggest that although amnesic patients can show impairments on implicit and explicit conceptual memory tasks, their deficit does not generalize to all conceptual memory tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The relationship between recall and recognition in amnesia: Effects of matching recognition between patients with amnesia and controls.

To examine the relationship between recall and recognition memory in amnesia, the authors conducted 2 experiments in which recognition memory was equated between patients with amnesia and control participants. It was then determined whether recall was also similar across groups. In Experiment 1, recognition was equated by providing amnesic patients with additional study exposures; in Experiment 2, recognition was equated by testing controls following a longer delay. These different methods of equating recognition across groups led to divergent results because amnesic patients' recall performance was lower than controls' recall performance in Experiment 1 but not in Experiment 2. These findings are accounted for by considering the differential contribution of recollection and familiarity to the performance of amnesic patients and controls in the 2 experiments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Level-of-processing effects in word-completion priming: A neuropsychological study.

Recent reviews (A. S. Brown & D. B. Mitchell, see record 82:16176; B. Challis & D. R. Brodbeck, see record 79:30007) concluded that level-of-processing (LOP) manipulations affect priming in perceptual tasks, contrary to earlier suggestions that such tasks are insensitive to LOP. In 3 experiments with amnesic patients and control Ss, the authors examined the effect of LOP manipulations on priming in word-stem and word-fragment completion and on recognition memory. Amnesic patients exhibited reduced or near-zero LOP effects in word-completion priming compared with controls. LOP affected recognition memory for both amnesic patients and control Ss, confirming that the LOP manipulation affected explicit memory. When the effect of explicit retrieval on control performance was reduced by using a low-level encoding task, priming was the same for amnesic patients and controls. The authors suggest that LOP effects in word-completion priming tasks reflect the influence of explicit retrieval, which can be used usefully by control Ss but much less so by amnesic patients. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recognition memory and familiarity judgments in severe amnesia: No evidence for a contribution of repetition priming.

The amnesic patient E.P. has demonstrated normal levels of repetition priming and at-chance recognition performance (S. B. Hamann & L. R. Squire, 1997), suggesting that the sense of familiarity used to make a recognition memory judgment is not based on the same mechanism responsible for repetition priming. However, the recognition tests previously used may have discouraged the use of familiarity and encouraged reliance on episodic memory. This issue was addressed in 5 experiments with E.P., 3 other amnesic patients with hippocampal damage, and 8 healthy controls. In Experiments 1–3, which were designed to discourage the use of episodic memory, the amnesic patients were impaired and E.P. performed at chance. In Experiments 4 and 5A, a stem-completion priming task was combined with a recognition memory task on each trial. E.P.'s priming was intact, yet his recognition memory performance was at chance. This suggests that although recognition memory judgments may be made on the basis of familiarity, repetition priming is not the source of this feeling of familiarity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Priming and baseline perceptual identification performance in amnesia: A comment on Hamann, Squire, and Schacter.

There is evidence that stimulus processing deficits, some of which may be due to striatal damage, are prevalent in memory-impaired patients. The deficits often result in impaired baseline performance in implicit memory tasks, which in turn is associated with increased priming effects. When priming scores were corrected for such processing deficits, the authors found a relationship between priming and both recognition memory and mesial temporal lobe damage. On the basis of 4 tachistoscopic word identification experiments, S. B. Hamann et al (see record 1995-14158-001) challenged the notion that either processing deficits or striatal damage is prevalent in amnesia patients. They claim that both priming and baseline word identification are normal in amnesia patients, except that patients with Korsakoff amnesia show deficits under certain restricted circumstances. The authors argue that the results of the Hamann et al study are entirely consistent with their previous reports. When Hamann et al did not find differences between amnesia patients and controls in word identification, the results were contaminated by ceiling effects, and there was poor control over the effective exposure duration of the stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuropsychological deficits in patients with an anterior communicating artery syndrome: a multiple case study

The neuropsychological performance of five patients with an anterior communicating artery (ACoA) syndrome (amnesia, confabulation and personality changes) was studied. Neuroimaging techniques revealed a basal forebrain and frontal lobe pathology in all patients. The limbic system appeared intact. There was no evidence for an intellectual deterioration relative to the estimated premorbid IQ in four patients. Regarding attention, all patients showed significant deficits. Visuospatial disabilities could not be observed. On tests of executive functioning, all patients did exhibit severe problems. Every patient displayed a profound amnesic syndrome. A retrograde amnesia could be documented and was characterised by a temporal gradient. Short-term memory appeared normal. Concerning long-term memory, all patients scored out of the normal range on total immediate recall tasks. Four patients showed a normal recognition performance but produced a large number of false alarms. Despite a normal recognition performance, they were impaired in delayed recall tasks. However, one patient showed a full-blown amnesic syndrome, because his delayed recall and recognition of learned items were both depressed. Our results with regard to long-term memory functioning support the hypotheses which assume (1) the existence of recognition superiority and pathological false recognition, and (2) basal forebrain amnesia in ACoA patients.     

Human amnesia and animal models of amnesia: Performance of amnesic patients on tests designed for the monkey.

The performance of amnesic patients was assessed on five tasks, which have figured prominently in the development of animal models of human amnesia in the monkey. The amnesic patients were impaired on four of these tasks (delayed nonmatching to sample, object-reward association, 8-pair concurrent discrimination learning, and an object discrimination task), in correspondence with previous findings for monkeys with bilateral medial temporal or diencephalic lesions. Moreover, performance of the amnesic patients correlated with the ability to verbalize the principle underlying the tasks and with the ability to describe and recognize the stimulus materials. These tasks therefore seem to be sensitive to the memory functions that are affected in human amnesia, and they can provide valid measures of memory impairment in studies with monkeys. For the fifth task (24-hour concurrent discrimination learning), the findings for the amnesic patients did not correspond to previous findings for operated monkeys. Whereas monkeys with medial temporal lesions reportedly learn this task at a normal rate, the amnesic patients were markedly impaired. Monkeys may learn this task differently than humans. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Procedural memory system supports single cue trace eyeblink conditioning in medial temporal lobe amnesia.

A number of studies investigating trace eyeblink conditioning have found impaired, but not eliminated, acquisition of conditioned responses (CRs) in both animals and humans with hippocampal removal or damage. The underlying mechanism of this residual learning is unclear. The present study investigated whether the impaired level of learning is the product of residual hippocampal function or whether it is mediated by another memory system that has been shown to function normally in delay eyeblink conditioning. Performance of bilateral medial temporal lobe amnesic patients who had a prior history of participating in eyeblink conditioning studies was compared to a control group with a similar training history and to an untrained control group in a series of single cue trace conditioning tasks with 500 ms, 250 ms, and 0 ms trace intervals. Overall, patients acquired CRs to a level similar to the untrained controls, but were significantly impaired compared to the trained controls. The pattern of acquisition suggests that amnesic patients may be relying on the expression of previously acquired, likely cerebellar based, procedural memory representations in trace conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Theoretical and computational analysis of skill learning, repetition priming, and procedural memory.

This article analyzes the relationship between skill learning and repetition priming, 2 implicit memory phenomena. A number of reports have suggested that skill learning and repetition priming can be dissociated from each other and are therefore based on different mechanisms. The authors present a theoretical analysis showing that previous results cannot be regarded as evidence of a processing dissociation between skill learning and repetition priming. The authors also present a single-mechanism computational model that simulates a specific experimental task and exhibits both skill learning and repetition priming, as well as a number of apparent dissociations between these measures. These theoretical and computational analyses provide complementary evidence that skill learning and repetition priming are aspects of a single underlying mechanism that has the characteristics of procedural memory. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Emotional perception and memory in amnesia.

The authors examined whether perception of emotional stimuli is normal in amnesia and whether emotional arousal has the same enhancing effect on memory in amnesic patients as it has in healthy controls. Forty standardized color pictures were presented while participants rated each picture according to emotional intensity (arousal) and pleasantness (valence). An immediate free-recall test was given for the pictures, followed by a yes-no recognition test. Arousal and valence ratings were highly similar among the amnesic patients and controls. Emotional arousal (regardless of valence) enhanced both recall and recognition of the pictures, and this enhancement was proportional for amnesic patients and controls. Results suggest that emotional perception and the enhancing effect of emotional arousal on memory are intact in amnesia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intact and long-lasting repetition priming in amnesia.

In 2 experiments, the ability of amnesic patients to exhibit long-lasting perceptual priming after a single exposure to pictures was evaluated. Ss named pictures as quickly as possible on a single occasion and later named the same pictures mixed with new pictures. In Exp 1, amnesic patients exhibited fully intact priming effects lasting at least 7 days. In Exp 2, the priming effect for both groups was shown to depend on both highly specific visual information and on less visual, more conceptual information. In contrast, recognition memory was severely impaired in the patients, as assessed by both accuracy and response time. The results provide the 1st report of a long-lasting priming effect in amnesic patients, based on a single encounter, which occurs as strongly in the patients as in normal Ss. Together with other recent findings, the results suggest that long-lasting priming and recognition memory depend on separate brain systems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impaired recognition memory in patients with lesions limited to the hippocampal formation.

A recent literature survey of results from a widely used recognition memory test raised questions about the extent to which recognition memory impairment ordinarily occurs in human amnesia and, in particular, whether recognition memory is impaired at all after damage limited to the hippocampal region (J. P. Aggleton & C. Shaw, 1996). Experiment 1 examined the performance of 6 amnesic patients on 11 to 25 different recognition memory tests. Three patients had bilateral lesions limited primarily to the hippocampus (G.D.) or the hippocampal formation (W.H. and L.M.), as determined by postmortem, neurohistological analysis (N. Rempel-Clower, S. M. Zola, L. R. Squire, & D. G. Amaral, 1996). All 6 patients exhibited unequivocally impaired recognition memory. In Experiment 2, the 3 patients still available for study were each markedly impaired on a test of object recognition similar to the kind used to test recognition memory in nonhuman primates. Recognition memory impairment is a robust feature of human amnesia, even when damage is limited primarily to the hippocampus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recognition and recall in amnesics.

Examined whether recall is disproportionately disrupted by amnesia compared with recognition, using 7 amnesics (mean age 51 yrs) without a history of alcoholism, 9 amnesic alcoholic Korsakoff syndrome patients (mean age 66 yrs), and 9 controls (mean age 53.2 yrs). It was postulated that if amnesia affects memory uniformly across different direct memory measures, recall of normal controls should not differ from the recall of amnesics when recognition scores of these 2 groups are equated. On the other hand, if recall is disproportionately disrupted, normal recall should be superior to amnesic recall even when recognition is equated. In the present study, amnesic recognition was equated with that of controls by providing amnesics with 8 sec of study time and normal Ss with 0.5 sec. Normal recall was superior to amnesic recall even when no differences were found in recognition. The results further specify the selective nature of amnesia. It is suggested that amnesia reflects a selective disruption of an aspect of memory critical to successful recall. (47 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A dissociation between perceptual explicit and implicit memory processes

Patient M.S., who underwent right-occipital lobe resection to treat intractable epilepsy, has intact recall and recognition memory for words, but impaired repetition priming in word identification and visual stem-completion tasks. This mirror dissociation to amnesia suggests that explicit recognition and visuoperceptual repetition priming are mediated by distinct neural systems. In prior studies, however, M.S.' recognition memory was tested only with tasks that drew upon his intact verbal knowledge. The present study examined M.S.' recognition memory for nonverbal perceptual information, namely, the modality and font of word presentation and line patterns. M.S.' recognition memory was intact, providing further evidence that perceptual explicit and implicit memory processes are subserved by functionally and neurally independent memory systems.