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Biomedical subjects

P Meudell

Publications and source records attributed to P Meudell.

12 recordsLinked to original sources
PubMed1994

Long lasting indirect memory performance for abstract shapes in amnesics and matched controls.

The speed with which subjects copied complex geometrical shapes was used as an indirect memory measure in a group of 12 organic amnesics of several aetiologies and their matched controls, tested at two delays. Both subject groups were found to copy previous seen shapes faster than new foil shapes, and the magnitude of the speed up effect did not differ significantly between amnesics and matched controls when tested at two delays of 10 min and 24 hr, respectively. The size of the indirect memory effect did not decline across the delay in either group. In contrast to indirect memory performance, measured by two-choice recognition of the shapes, was impaired in the amnesic group and there was some suggestion that recognition performance declined across the delay in both subject groups.

Adult↗
PubMed1993

Preserved pattern completion priming for novel, abstract geometric shapes in amnesics of several aetiologies.

Two experiments were conducted using a paradigm developed by Gabrieli et al., Neuropsychologia 28, 417-427, 1990, which assessed both indirect and direct memory performance in a completion task for novel abstract geometric patterns. The preferred method of scoring was the lines method, based on the number of correct and incorrect lines produced for each item. It was chosen because it is both the simplest and the most informative measure. Two methods of scoring were used in previous work, namely, the strict whole figure method and the lenient whole figure method (Gabrielli et al., 1990; Verfaelie et al., Brain Cognit. 18, 34-45, 1992). Therefore to facilitate comparisons between studies and to determine the characteristics of different scoring methods, results with all three measures were included. In Experiment 1, two different encoding strategies of naming and copying were used in order to explore the relationship between indirect and direct memory performance. Indirect memory performance in the naming condition was at baseline whereas in the copying condition it was significantly above baseline. Cued recall did not differ across encoding conditions but recognition was higher in the naming condition than the copying condition. In Experiment 2, an attempt was made to extend the findings of two studies, one with H.M. (Gabrielli et al., 1990) and one with nine Korsakoffs (Verfaelie et al., 1992), to a larger group of 14 amnesics of several aetiologies. Indirect memory performance was found to be equivalent for the amnesics and their matched controls, only when the lenient and the lines methods of scoring were used. Recognition and cued recall performance was impaired for the amnesics compared to the controls.

Adult↗
PubMed1993

Short report: is spatial information encoded automatically in memory?

A dual-task paradigm was used to test Hasher and Zacks' (1979) hypothesis that spatial memory is automatic. Subjects saw two sets of 16 words each, the words being presented singly in random corners of a monitor screen. They were asked to remember the words and the corner in which each word was shown. In addition, subjects were given a concurrent task to perform. This task was either "easy" (counting aloud by ones) or "difficult" (counting aloud by sevens). Attention was focused either on the memory task or on the counting task. Word recognition was better when subjects carried out the easier competing counting task and when subjects concentrated mainly upon remembering the words and their positions. Contingent spatial memory was unaffected by either manipulation, supporting the hypothesis that spatial memory is automatic.

Adult↗
PubMed1990

Performance on tests sensitive to frontal lobe lesions by patients with organic amnesia: Leng & Parkin revisited.

Groups of amnesics with aetiologies that included chronic alcoholism, encephalitis and ruptured anterior communicating artery aneurysm (ACoAA) were examined on the Cognitive Estimation Test (CET), FAS Word Fluency Test (FAS) and the full and Nelson (1976) versions of the Wisconsin Card Sorting Test (WCST). The alcoholic amnesics were impaired on all four tests, whereas the post-encephalitic amnesics were impaired on the FAS and CET but performed normally on both versions of the WCST. The ACoAA amnesics were impaired on both the FAS and the CET, and scored at a level in between the other amnesic subgroups on the WCST.

Adult↗
PubMed1986

Amnesia can facilitate memory performance: evidence from a patient with dissociated retrograde amnesia.

A case is reported of a patient who experienced numerous episodes of transient global amnesia (TGA) during which anterograde amnesia was less prominent than usual, and who developed a permanent selective retrograde amnesia. On formal testing, he performed well on traditional verbal memory tests, but showed marked retrograde amnesia for verbal material, including items on a famous voices recognition test. He was administered a paired-associate learning test where the names of famous personalities for which he was amnesic were associated with incongruous activities (e.g. John Newcombe-singing). Our patient performed better on this task than a group of five matched control subjects. Our observations indicate that in the organization of human memory retrograde amnesia may be fractionated from anterograde amnesia and that in certain situations specific types of amnesia can produce a facilitation effect compared to the performance of control subjects.

Aged↗
PubMed1981

A similarity between weak normal memory and amnesia with two and eight choice word recognition: a signal detection analysis.

Two and eight choice recognition memory was compared in a group of normal individuals shortly after learning a list of words and seven days later. In addition to selecting the correct response, subjects were required to indicate the confidence of their choices. The results showed that eight choice recognition performance was differentially worse than two choice recognition at delayed compared to immediate test. These results were similar to some reported by Miller (1977) in which he compared recognition in dementing amnesics and controls at immediate test. While Miller interpreted his data in terms of a selective retrieval deficit in amnesics, our data suggests that both sets of results arise because Signal Detection Theory is applicable to recognition memory data. An additional result was that subjects felt they guessed correctly selected words more frequently after a delay.

Adult↗
PubMed1981

How similar is the effect of cueing in amnesics and in normal subjects following forgetting?

Verbal recognition and cued recall were compared in normal subjects after intervals of 15 minutes, one week and six weeks. When given cues subjects were encouraged to produce as many appropriate words as possible in a 30 second period and rate the words for familiarity. Guessing controls were used and subjects' skill at generating words without a memory component was also assessed. The results confirmed others in showing that cued recall declines more slowly over time than recognition. Further, although subjects cued well at six weeks they did not feel correctly cued words to be familiar. A similar effect has been noted with amnesic cueing. Also, at the six week interval, correct words tended to be generated later than after the shorter intervals, and there was a correlation between cued recall and cueing skill in general. These findings suggest that normal subjects who have largely forgotten and, probably, also amnesics use cues differently from normal subjects who are tested immediately after learning.

Adolescent↗
PubMed1980

Is amnesia caused by an activational deficit? A preliminary electrophysiological investigation of acquisition in amnesics.

Six alcoholic amnesics were compared with 6 matched controls in a task involving visual presentation of words under 'learn', 'repeat' and 'passive' instructions whilst their EEG was recorded from the vertex. Although the amnesics' N2-P3 component to word stimuli was similar to that of controls, their word-elicited N1-P2 component was of greater amplitude and their EEG showed an overall reduction in power in the period immediately following word offset. The group difference for N1-P2 was similar in all instructional conditions, but the EEG power difference was greater in the learn condition. It was argued that the N1-P2 enhancement may reflect an attempt by the amnesics to compensate for an unspecified activational impairment indicated by their reduced post-word EEG power.

Alcoholism↗
PubMed1980

Amnesia is not caused by cognitive slowness.

It has been suggested that the memory disorder in human organic amnesia might be caused by the slow processing of information. Such slowness might be differentially greater for semantic tasks, and/or for tasks requiring the extraction of multiple features of stimuli, or it might simply be a non-specific slowing. These possibilities were tested in a group of alcoholic amnesics and matched normal controls by presenting subjects with a series of words and requiring them to identify one specified word or one of two specified words, or membership of a specified category or one of two specified categories. Although amnesics' reaction times were slightly slower than controls' the effect was insignificant, and there was no hint of differential slowing in the semantic or multiple processing tasks. It was concluded from these results and a consideration of the reaction time literature that cognitive slowness is unrelated to the main cause of amnesia.

Alcohol Amnestic Disorder↗