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P Rabbitt

Publications and source records attributed to P Rabbitt.

35 records · Page 2Linked to original sources
PubMed1994

Minor head injury: pathophysiological or iatrogenic sequelae?

This study addresses the possibility that cognitive sequelae--albeit of a transient or minor character--can be associated with mild head injury. Twenty men (aged 16-30 years of age), whose post-traumatic amnesia did not exceed eight hours, were examined within 48 hours of their accident and again one month later. This unselected sample had no previous history of head injury. A control group of 20 men of similar socioeconomic background, was selected from medical wards (where they had been admitted for orthopaedic treatment or a minor operation). They were also retested one month after the first examination. Neuropsychological tests were selected to measure abilities often compromised after significant head injury, namely memory and attention. The experimental component consisted of the fractionation of a complex skill (paced addition) to probe for deficits at different stages of information processing: perception and input into storage; search for and retrieval of information from working memory; and paced and unpaced addition. In general, no significant difference was found between the experimental and control groups, with the possible exception of an initial decrement on two working memory tasks: probe digits and a keeping track task (where the subject has to keep in mind and update a number of variables at the same time). The keeping track paradigm, ostensibly of ecological relevance, may well be worth further exploration in memory research, and in studies of more severely head-injured patients. It is further suggested that the appropriate management and counselling of mildly head-injured patients may help to avert symptoms that are of psychological rather than pathophysiological origin.

Adolescent↗
PubMed1993

Does it all go together when it goes? The Nineteenth Bartlett Memorial Lecture.

As groups of people age, the differences in the cognitive abilities of the most and least able become more extreme. This increase in between-individual variance is accompanied by an increase in within-individual variance: the difference between individuals' levels of performance on their best and least well retained skills. The implications of increasing between-individual variance are discussed in terms of the range of different factors that may affect cognitive ageing. Increases in within-individual variance are discussed in terms of differences between "fluid" and "crystallized" abilities. The usefulness of this distinction and its functional implications are questioned. The hypothesis that age-related declines in "fluid" abilities are best modelled in terms of declines in a single factor is evaluated. Evidence is presented of disparate rates of decline, even of "fluid" cognitive abilities, such as performance on IQ tests, ability on information-processing tasks, and efficiency on memory tasks. Data from large-scale cross-sectional studies suggests that cognitive skills do not "all go together when they go," but that there may rather, be characteristic patterns, or syndromes, of cognitive ageing.

Adult↗
PubMed1991

Do older people know how good they are?

Information and procedures that have been overlearned during a lifetime form a body of 'crystallized' intelligence that is relatively unaffected by ageing. Thus in spite of marked decrements in their 'fluid' memory abilities it is possible that older people may retain knowledge about the limitations and characteristics of their own memory ('metamemory'). To test whether efficiency of metamemory is, indeed, independent of age-related decline in fluid intelligence, 320 people aged from 50 to 79 years were asked to predict their probable performance on four simple memory tasks which had been carefully explained to them. They then experienced the tasks and their predictions were compared with their actual performances. Actual task performance was modestly predicted by chronological age and by AH 4 and Mill Hill IQ test scores but not by subjective self-ratings of everyday memory and cognitive efficiency (the Broadbent CFQ, and the Sunderland & Harris MQ). The data suggest that absolute levels of prediction of performance were associated with self-confidence and were best predicted by scores on the Beck depression scale and by fluid IQ test scores. There was also evidence that individuals with higher test scores gave more accurate as well as more optimistic predictions of their own abilities. Taken together these results suggest that the accuracy of individuals' assessments of their own abilities does alter with age-related changes in fluid IQ, but probably more radically by age-related changes in self-regard and in life-style.

Activities of Daily Living↗
PubMed1990

'Lost and found': some logical and methodological limitations of self-report questionnaires as tools to study cognitive ageing.

Laboratory tests show a decline in memory efficiency with age, but may not reflect highly practiced everyday memory skills. Self-rating questionnaires probe memory efficiency in everyday life, but seven logical and methodological problems ambiguate interpretation of the data they yield. To explore these problems, 442 volunteers aged from 50 to 85 years were given the AH 4 IQ tests, Mill Hill Vocabulary Tests, Beck Depression Inventory (BDI), Broadbent Cognitive Failures Questionnaire (CFQ), Sunderland & Harris Memory Failure Questionnaire (MFQ), the 'Lost and Found' Questionnaire (LF, a new domain-specific probe of the variety, frequency and aetiologies of losses of possessions) and two laboratory memory tests. All self-rating questionnaire scores correlated modestly with each other. Counter-intuitively, individuals over 60 years old reported fewer lapses on the LF and on the CFQ. No SRQ scores correlated with performance on laboratory tasks. CFQ scores did not correlate with IQ test scores but high IQ test scorers reported greater recent decline in memory efficiency (MFQ) and greater current frequency of losses of objects (LF). CFQ and LF scores correlated positively with Beck Depression Inventory scores, suggesting some common loading for poor self-regard. The results suggest that subjective self-ratings cannot reflect absolute levels of everyday competence, but only the relative success of individuals' adaptations to idiosyncratic environments which, as they age, may change faster than their abilities. However, besides exposing the limitations of self-report techniques, these analyses also suggest practical ways of adapting and using SRQs which may allow us to gain better insights into changes and individual differences in functional efficiency in everyday life.

Aged↗
PubMed1990

Mild hearing loss can cause apparent memory failures which increase with age and reduce with IQ.

Rabbit (1968) tested the accuracy with which young adults with excellent hearing could repeat lists of numbers, words or continuous text which they heard over a system which maintained a constant ratio of white noise to speech signal irrespective of signal strength. Noise levels which allowed individual subjects correctly to repeat every word as they heard it (i.e. shadow without errors) nevertheless reduced their ability to remember what they had heard. This appeared to be because increased effort necessary to recognise words through low levels of noise prevented adequate rehearsal or elaborative encoding of material to be remembered. This finding that slight degradation of sensory input had secondary consequences on memory and comprehension of spoken material led to an interpretation of findings that 960 individuals aged from 50 to 82 years, in contrast to young adults, showed markedly better recall for word lists presented visually than for word lists presented auditorally, even when each word in each list was correctly read or repeated aloud. Audiometric screening of a sub-set of this population allowed 30 individuals with mild hearing losses (35 to 50 db) in each of the three age-decades 50 to 59, 60 to 69 and 70 to 79 years to be compared with matched controls who had pure-tone hearing losses of less than 35 db on memory for lists of 30 words presented visually or over a good-quality sound system. In both presentation modes lists were only scored if all words were correctly read or repeated. Individuals with slight hearing loss recalled visually presented words as well, but recalled auditorally presented words significantly less well, than their controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Do clever old people have earlier and richer first memories?

In a study of 377 people, from 54 to 83 years old, it was shown that the age of earliest memories was unrelated to current age but was related to intelligence. People with high IQ test scores remembered first and second memories at an earlier age than did those with lower IQ test scores. Intervals between first and second memories were briefer for those with high scores. The content of early memories was unrelated to age or intelligence.

Aged↗
PubMed1980

Selective anticipation for events in old age.

When considering how momentary variations in attentional selectivity occur it is useful to distinguish between situations in which selectivity is controlled by external events (data-driven control) and other situations in which people use their previous experience to actively adjust their attentional selectivity from moment to moment (memory-driven control). In terms of this distinction Experiment 1 suggests that elderly people show preservation, or even enhancement, of data-driven control but loss of memory-driven control of selective attention. A general conclusion is that as people grow older they become more labile, and more subject to control by external events. Experiment 2 suggests that one possible reason may be that old subjects remember, analyse, and employ smaller samples of the recent past when they are computing what is most likely to happen next.

Adolescent↗
PubMedDate not supplied

Age, IQ and awareness, and recall of errors.

Younger people report more lapses than the elderly on the Broadbent Cognitive Failure Questionnaire, the Harris and Sunderland Memory Failure Questionnaire, and a 'Lost and Found' questionnaire. Lapses are not predicted by IQ or vocabulary test scores (AH 4 parts 1 and 2, and Mill Hill). These paradoxical findings reveal some logical and methodological difficulties in the interpretations of subjective self-ratings. Age and IQ differences in the memorability of errors were illustrated using choice reaction time (CRT) tasks. All age groups were equally efficient at 'automatic' error detection and correction, but older individuals more often omitted controller error-signalling responses. Errors followed by controlled responses were better remembered. It is argued that conscious self-monitoring and the ability to remember errors improves with IQ and declines with age.

Adolescent↗
PubMedDate not supplied

Cambridge Neuropsychological Test Automated Battery (CANTAB): a factor analytic study of a large sample of normal elderly volunteers.

The CANTAB battery was administered to a large group (n = 787) of elderly volunteers in the age range from 55 to 80 years. This battery, which is based on tests used to identify the neural substrates of learning and memory in non-human primates, has now been extensively used in the assessment of various forms of dementia and also validated on patients with neurosurgical lesions of the frontal and temporal lobes. The tests employed were pattern and spatial recognition, simultaneous and delayed matching to sample, learning of visuospatial paired associates, a matching to sample, reaction time task and a test of spatial working memory. The sample was banded into different IQ bands based on performance on 5 standard tests of intelligence. The MMSE was also administered to exclude cases of possible dementia (n = 16) in the normal sample. In general, performance declined with age and IQ, but these factors did not interact. A factor analysis (with varimax rotation) identified 4 factors with eigenvalues greater than 1, which accounted for over 60% of the variance. Factor 1 was equated with general learning and memory ability and loaded significantly with the Intelligence scores; factor 2 was related to speed of responding and loaded most heavily with Age. Comparisons were also made of performance on CANTAB of those subjects with dementing scores on the MMSE and the lowest 5th percentile of the population sample. The results are discussed in terms of the utility of the CANTAB battery for the assessment of dementia and of the implications for theories of changes in cognitive function during normal aging.

Aged↗
PubMedDate not supplied

The University of Manchester Age and Cognitive Performance Research Centre and North East Age Research Longitudinal Programmes, 1982 to 1997.

The United Kingdom Medical Research Council and Economic and Social Research Council have funded, since 1982, a longitudinal study of cognitive change in old age carried out on over 6000 volunteers aged between 50 and 96 years and resident in Newcastle-upon-Tyne and Greater Manchester. The Medical Research Council has guaranteed further funding until 1977. This paper describes the history of the study, the test batteries employed, the demographics of populations tested and the amount, and selectivity, of attrition by death and withdrawal from the study. Further aims of the study, and parallel work carried out on a number of related projects concerned with the epidemiology, time-course and everyday impacts of cognitive changes in normal old age are also discussed.

Aged↗