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Query: UMLS:C0598853 (forgetting)
 3,232 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Seven cynomolgus monkeys (Macaca fascicularis) performed a series of tasks designed to assess their visual memory and their ability to identify visual stimuli. Preoperatively they were trained and tested in delayed and simultaneous matching-to-sample, both with a large stimulus set and with a small stimulus set; there were approximately 500 million possible stimuli in the large set, which effectively means that stimuli were trial-unique with this set, while in the small set there were only four stimuli, which appeared repeatedly in every session of training with the small set. Three of the monkeys then had the cortex within and adjacent to the rhinal sulcus removed bilaterally, while the other four served as an unoperated control group. Postoperatively, the animals with ablation of the rhinal cortex showed severe impairment in delayed matching-to-sample with the large set. With the large set they were also impaired, however, in matching-to-sample with no delay between sample and test (0 s delay) and in simultaneous matching-to-sample, in which the sample and the two choice patterns were simultaneously present for inspection. The impairment in simultaneous matching-to-sample was particularly clear when the task was made more difficult by reducing the physical discriminability of the trial-unique stimuli. With the small set of four stimuli, the animals with rhinal cortex ablation were not significantly impaired in overall performance level in delayed matching-to-sample, though their level was on average below that of the normal control animals. The stimulus set was then further restricted, so that there were now only two stimuli used throughout; in this condition, the animals with rhinal cortex ablation performed delayed matching-to-sample without any suggestion of impairment, showing indistinguishable performance levels from those of the control animals over a range of forgetting intervals. Subsequently, the animals were trained in trial-unique non-matching-to-sample with 0 s delay, which required reversal of the matching-to-sample rule they had previously learned; animals with rhinal cortex ablation showed a clear impairment in this rule-reversal learning. The final experimental task was a concurrent discrimination learning task in which 20 pairs of stimuli were presented once per session; the animals with rhinal cortex ablation learned more slowly than the control animals on average, but the difference between the groups did not attain statistical significance.(ABSTRACT TRUNCATED AT 400 WORDS)
Eur J Neurosci 1994 Sep 01
PMID:Preserved recognition memory for small sets, and impaired stimulus identification for large sets, following rhinal cortex ablations in monkeys. 800 May 70

Ss aged 52-83 years were asked to name 30 famous people 4 times over the course of an hour and to respond to 2 targets (a beard and a pipe) by marking the trial number on the response sheet. Initial performance in the prospective memory task was related only to a measure of incidental learning. Subsequent forgetting (i.e., success followed by failure) occurred more often for older Ss than for younger Ss, but there was no difference between the age groups in recovery (i.e., failure followed by success). Forgetting was predicted by age, even after a composite measure of general ability was included in the regression. Recovery was related to general ability alone. These results both replicate and extend those from a reanalysis of a previous study (Maylor, 1990a). They provide a striking contrast with the effect of age on retrospective memory, namely, age-related impairment on initial performance but no effect of age on subsequent forgetting.
Psychol Aging 1993 Sep
PMID:Aging and forgetting in prospective and retrospective memory tasks. 821 62

Age comparisons of performance-based measures of forgetting were carried out. In Exp. 1, 18- to 21-year-olds and 55- to 64-year-olds (n = 24) forgot at an equal rate when compared at 30 s and at 3, 6, and 24 hr after acquisition. In Exp. 2, 17- to 21-year-olds and 65- to 74-year-olds (n = 24) were compared at the same 4 retention intervals. Initial learning was equated for the 2 groups. There was evidence for an age difference in forgetting rate in cued recall when a minimal learning level was required. In Exp. 3, 440 men and women 17 to 74 years old were assigned to a retention interval from 10 min to 7 hr. Age was related to 4 performance-based measures of forgetting rate. Although the age differences were small, they imply 2 decremental processes: 1 before 10 min, possibly a result of incomplete consolidation, and a later 1 that is continuously and cumulatively operative thereafter. Evidence relating initial level to forgetting rate is presented.
Psychol Aging 1993 Sep
PMID:Adult age differences in forgetting sentences. 821 66

Following a thoracic trauma, which caused brain hypoxia, a 24-year-old man presented with a dense retrograde amnesia for events, persons and environments that spanned his whole life before injury. Knowledge acquired at school or through the media were equally lost, with the exception of arithmetical skills and some geographical knowledge. No deficit was apparent in language, object recognition, motor skills and intellectual tests. Anterograde memory was marked by very efficient learning capacity, an almost perfect retention of information at delay interval of 4 hours and pathologically rapid forgetting at longer delays. Informal observations agreed with test performance in showing that he could relearn facts of the past and easily acquire new information, but tended to lose these memories if the information was not frequently rehearsed. PET showed a hypometabolism of the posterior temporal lobes. Though some points remain obscure, we propose that a consolidation deficit hypothesis provides the most sensible interpretation of this peculiar pattern of memory deficit.
Cortex 1993 Sep
PMID:Dense retrograde amnesia, intact learning capability and abnormal forgetting rate: a consolidation deficit? 825 85

This study further examines the performance of diencephalic and temporal lobe amnesics on the recency judgement task (Parkin, Leng and Hunkin, 1990). The two patient groups were represented by patients with Wernicke-Korsakoff syndrome (WKS) and post-Herpes simplex encephalitis (HSE). Experiment 1 demonstrated that poorer recency judgements by WKS patients were not due to a general proactive interference effect, but from an inability to remember which items had been designated targets on a given trial. Experiment 2 demonstrated that the superior performance of the HSE group was not attributable to a putative faster forgetting rate. In addition, the study found no relationship between recency judgements and degree of frontal lobe impairment. It is concluded that diencephalic damage has a particular effect on the ability to make recency judgements and that this represents a fundamental difference between diencephalic and temporal lobe amnesia. Theoretical interpretations of this difference are discussed.
Cortex 1993 Sep
PMID:Recency judgements in Wernicke-Korsakoff and post-encephalitic amnesia: influences of proactive interference and retention interval. 825 87

Accelerated forgetting of name-face associations and grocery list items within the first hour postpresentation is demonstrated in 80 persons with Alzheimer's disease (AD) compared to 80 control subjects matched on age, education, and gender. Differences in forgetting which exceeded statistical regression effects remained, even when AD and control subjects were matched on rate of acquisition during the learning trials of name-face associations. Results are discussed in relation to the neuropathology of AD, organic amnestic disorders, and methodological factors concerning previous research on forgetting in persons with AD.
J Clin Exp Neuropsychol 1993 Sep
PMID:Accelerated forgetting in Alzheimer-type dementia. 827 30

Recent research has demonstrated that patients with dementia of the Alzheimer type (DAT) evidence more rapid forgetting than do patients with Huntington's disease (HD). The present study focused on whether such group differences translated into measures with adequate sensitivity and specificity at different stages of these disorders. It was found that measures of forgetting (i.e., savings scores) based upon the Logical Memory and Visual Reproduction tests of the Wechsler Memory Scale--Revised had satisfactory to excellent sensitivity and specificity in differentiating DAT and HD patients from healthy control subjects. Savings scores also had good sensitivity and specificity in differentiating DAT from HD in the early stages of the diseases. However, unsatisfactory specificity may limit the utility of savings scores in differentiating among patients with moderate DAT and HD.
J Clin Exp Neuropsychol 1993 Sep
PMID:The diagnostic utility of savings scores: differentiating Alzheimer's and Huntington's diseases with the logical memory and visual reproduction tests. 827 35

Several examples of experience-dependent perceptual improvement (perceptual learning) suggest that plasticity in specific neuronal loci could underlie the learning process. For a basic visual discrimination task (using an optimal stimulus for 'automatic' pre-attentive texture segregation), discrete retinal input-dependent changes within a very early stage in the stream of visual processing were indicated as the locus of a large and consistent learning effect. When do these changes occur? Here we report that except for a fast, rapidly saturating improvement early in the first practice session, performance was very stable within sessions. Indeed, observers showed little or no improvement until up to 8 hours after their last training session (latent phase). But large improvements occurred thereafter. Finally, there was almost no forgetting; what was gained was retained for at least 2-3 years. We conjecture that some types of perceptual experience trigger permanent neural changes in early processing stages of the adult visual system. These may take many hours to become functional.
Nature 1993 Sep 16
PMID:The time course of learning a visual skill. 837 79

Two experiments were performed to investigate the buildup of repetition priming in a lexical decision task with repeated presentations and its decline over the course of 2 months. Priming was found to accumulate as a power function of presentations and to decline as a power function of time. Accuracy measures indicated that the loss rate of priming was unaffected by the amount of initial priming. Response time measures indicated the same result when the experiments were analyzed separately; however, when the data were combined, increased initial priming was associated with greater losses in priming over time. The data were interpreted in terms of automaticity, and the power function decline in priming was taken as support for memory-based models of automaticity. Possible ways to incorporate forgetting into memory-based theories of automaticity are discussed.
Mem Cognit 1993 Sep
PMID:The loss of repetition priming and automaticity over time as a function of degree of initial learning. 841 13

In two experiments, subjects recalled one of two letter segments following a digit-filled retention interval. In Experiment 1, recall expectancy was manipulated by using precues that correctly informed or misinformed subjects concerning which letter segment would be tested for recall. In Experiment 2, item importance was varied by precuing one segment as important but requiring that the uncued segment be recalled first. Recall performance was very low under conditions of low expectancy and low segment importance, but the slopes of the retention functions did not demonstrate more rapid forgetting than under standard conditions. The previous observations of very rapid forgetting from primary memory may be a function of an elevated initial recall level in the earlier studies. Our retention functions were compared with predictions of the Estes perturbation model. The findings suggested that when secondary memory processes were reduced, forgetting order information from primary memory occurred at the same rate as that estimated on the basis of previous studies using the standard distractor task.
Mem Cognit 1993 Sep
PMID:Is there really very rapid forgetting from primary memory? The role of expectancy and item importance in short-term recall. 841 18


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