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Biomedical subjects

D E Broadbent

Publications and source records attributed to D E Broadbent.

At least 19 recordsLinked to original sources
PubMed1991

Short term prospective study of cognitive functioning in lead workers.

In a short term prospective study 70 male lead workers performed a series of cognitive tasks on three occasions during an eight month period. Concurrently with the cognitive testing, the concentrations of blood lead, zinc protoporphyrin (ZPP) and urinary aminolaevulinic acid (ALA) were measured. Indicators of lead absorption were stable during the study and each subject was allocated to either a low (below 20 micrograms/dl), medium (21-40 micrograms/dl), or high (41-80 micrograms/dl) group on the basis of their average blood lead concentrations. Performance deficits tended to be restricted to the high lead group and, in general, neither practice nor continued exposure during the study altered the magnitude of these deficits. The main deficit was a slowing of sensory motor reaction time, which was seen most clearly when the cognitive demands of the task were low. In the cognitively simple five choice task, blood lead concentration correlated with impaired decision making, response execution, and "lapses in concentration." In the other cognitive tasks the high blood lead group tended also to be slower by a factor of about 1.08 but the dominance of cognitive over sensory motor demands attenuated the exposure-performance correlations. The high lead group also had difficulty in recalling nouns poorly related to the focus of an earlier semantic classification task. This difficulty increased over time and was one of the few findings that correlated with all measures of lead absorption. It is concluded that the primary psychological profile of lead impairment is one of sensory motor slowing coupled with difficulties in remembering incidental information.

Adult↗
PubMed1990

Effective decisions and their verbal justification.

Recent experimental work on human control of complex systems has drawn attention to the discrepancy that may exist between the person's reported knowledge of the system and their ability to control it. Sometimes people act correctly but cannot answer questions about what they are doing; sometimes they can say verbally what they should do (perhaps having had verbal instruction in the right answers), but still do not do it. This discrepancy is of major practical importance, for example in designing training programmes or in eliciting expert knowledge for incorporation in a mechanical 'expert system'. It is also puzzling for psychological theory, as it rules out certain plausible models of the functioning of the brain. This paper considers what mechanisms are still possible.

Decision Making↗
PubMed1990

The processing of non-target words: semantic or not?

It is known that people reacting to visual words may be affected by the meaning of accompanying non-target words. On the approach to perception developed by Treisman (e.g. 1986), this is surprising, because meaning might be thought to require analysis of conjunctions of physical features and so should remain uncomputed for non-target words. Treisman's approach does, however, assert that analysis of the target may unleash further processes that would prime the system for detection of related words. If this were so, then presentation of the target earlier than the distractors would increase the effect of the latter; whereas if analysis of non-targets were independent of priming, they might be expected to have a smaller effect when delayed. Further, if the sets of words involved are small and familiar, then individual features of primed non-targets, rather than conjunctions of features, might trigger interference. They might especially do so when spatial separation of target and non-target is small. Five experiments using a paradigm developed by Shaffer and LaBerge confirm that the meaning of non-target words affects response to targets; but (1) this is more true for early than for late arrival of the target; (2) it is affected by target/non-target separation in space; (3) it is true for familiar sets of repeated words but not, in these data, for words used once only in the experiment. It is therefore concluded that the results are more consistent with a Treisman type of explanation than with a theory of universal and automatic full analysis.

Adolescent↗
PubMed1990

Work preferences as moderators of the effects of paced and unpaced work on mood and cognitive performance: a laboratory simulation of mechanized letter sorting.

This article describes a laboratory study of work preferences (ideal job demand and discretion levels) as moderators of the effects of paced and unpaced work on cognitive and affective responses. Posttest measures of cognitive performance and self-reported stress and arousal were used as outcome measures with covariance control for the corresponding pretest values. The experimental design allowed within-subjects contrasts of fast versus slow pacing and of machine-paced versus self-paced conditions. Self-paced performance compared favorably with machine-paced performance; however, individual differences in ideal demand influenced the relative speed of work under the two conditions. Work preferences also moderated relationships between pacing and outcome measures; ideal discretion moderated machine-pacing versus self-pacing effects in relation to cognitive performance and stress, and ideal demand moderated fast versus slow pacing effects in relation to arousal. These findings are discussed in relation to existing literature on pacing and on person-environment fit.

Adult↗
PubMed1989

Cognitive functioning in lead workers.

In a cross sectional study of occupational exposure to inorganic lead 91 men performed a series of microcomputer based tasks assessing sensor motor reaction time, memory, attention, verbal reasoning, and spatial processing. Performance on the tasks was studied in relation to three ranges of blood lead concentration (low, less than 20 micrograms/dl; medium, 21-40 micrograms/dl; and high, 41-80 micrograms/dl) and exposure response correlations for blood lead concentration, zinc protoporphyrin (ZPP) (range 7-210 micrograms/dl), and urinary aminolaevulinic acid (ALA) (range 0.5-22.0 mg/l). The results show that the high group were impaired on most of the tasks used and, in general, the magnitude of the impairment correlated better with blood lead concentration than ZPP or urinary ALA. An examination of the patterns of task impairment indicated a general slowing of sensory motor reaction time which was relatively independent of the nature of the cognitive functions being tested. There was some evidence, however, suggesting mild impairment of attention, verbal memory, and linguistic processing. In general, workers with high blood lead concentrations showed clear impairment of sensory motor functions in the absence of correspondingly strong evidence for impaired processing and memory functions. It is argued that a general slowness in responding may underlie many previous reports of widespread cognitive impairment in lead workers.

Adult↗
PubMed1988

Mood and cognitive functions in anaesthetists working in actively scavenged operating theatres.

Twenty-two anaesthetists participated in a study to assess the influence of occupational exposure to anaesthetic agents on mood (arousal and stress) and cognitive functions. In a cross-over design, each anaesthetist worked one day in a reference facility (for example, intensive care) and another day in a scavenged operating theatre where time-weighted exposure averaged nitrous oxide 58 p.p.m. and halothane 1.4 p.p.m. The results showed that arousal scores reached a peak in the middle of the theatre day, but this appeared to reflect the nature of operating theatre work rather than exposure. Reports of stress were also unaffected by exposure, although higher scores were associated with longer and more demanding work. Similarly, there was no evidence that exposure impaired performance of tasks assessing syntactic and semantic reasoning, verbal and spatial memory, sensory-motor reaction time and attention. Performance in these tasks was, however, sensitive to the cognitive demands of the tasks and to naturally varying non-exposure factors. It is concluded that, compared with the reference condition, the concentrations of anaesthetic agents found in actively scavenged operating theatres have no detrimental effect on either the mood or the cognitive functions of anaesthetists.

Adult↗
PubMed1988

Negative self-schema: the effects of induced depressed mood.

A depth-of-processing incidental recall paradigm, previously used as a measure of negative self-schema in depressed patients (Derry & Kuiper, 1981), was administered to normal subjects in whom depressed or neutral mood had been induced. Subjects in whom depressed mood was induced showed a pattern of recall similar to that previously found for depressed patients, suggesting (1) that at least some of the effects observed in depressed patients were a function of transient mood state, rather than persistent characteristics, and (2) that these effects of depressed mood also occur in individuals who have not been selected for vulnerability to clinical depression.

Adult↗
PubMed1987

Spatial factors in visual attention: some compensatory effects of location and time of arrival of nontargets.

It is well established that the identity of nontarget events may affect reaction to a target event, but that spatial separation between the two will reduce such an influence. Two experiments are reported in which an attempt was made to distinguish between two accounts of this effect. On one, some of the information about events spatially distant from the target is shut out from analysis altogether. On the other, such events are fully analysed, but either the analysis proceeds more slowly or else it starts only after a delay. In the experiments the time of arrival of, and the distance between, the target and nontarget events were systematically varied. The conventional effects of the distance of nontargets from target were greatly reduced when the target and nontarget events were asynchronous. If the nontargets arrived first, they had an effect on reaction to the target whether they were near to or far from it. If they arrived second, their identity had no effect at either separation. These results appear to rule out any simple view of attention according to which information outside the target region is denied analysis. Rather, distant nontarget events are analysed, but produce their effects at a later time than less peripheral events.

Adolescent↗
PubMed1986

Performance correlates of self-reported cognitive failure and of obsessionality.

In six experiments, two performance tests, measuring a number of aspects of attention, were administered to 129 people from the general population. Self-reported cognitive failure, and a measure of obsessional personality, were related to one particular measure of attention. There was evidence that individuals with low cognitive failure show different patterns of attention when anxious, as compared with high scorers; this may underlie differences in vulnerability to environmental stresses.

Adolescent↗
PubMed1985

The clinical impact of job design.

This paper summarizes some of the evidence that particular features of jobs are associated with particular types of neurotic symptoms, in a way consistent with broader views both of cognitive psychology and biological studies of stress. Particular emphasis is placed on interactive effects of certain characteristics of individuals, making them more or less vulnerable to stress.

Adaptation, Psychological↗
PubMed1985

Health of workers exposed to electric fields.

The results of health questionnaire interviews with 390 electrical power transmission and distribution workers, together with long term estimates of their exposure to 50 Hz electric fields, and short term measurements of the actual exposure for 287 of them are reported. Twenty eight workers received measurable exposures, averaging about 30 kVm-1h over the two week measurement period. Estimated exposure rates were considerably greater, but showed fair correlation with the measurements. Although the general level of health was higher than we have found in manual workers in other industries, there were significant differences in the health measures between different categories of job, different parts of the country, and in association with factors such as overtime, working alone, or frequently changing shift. After allowing for the effects of job and location, however, we found no significant correlations of health with either measured or estimated exposure to electric fields.

Anxiety↗
PubMed1984

Some further studies on the prediction of experimental colds in volunteers by psychological factors.

An analysis of the incidence of colds in volunteers, exposed experimentally to various rhinovirus and influenza virus challenges, confirmed an earlier report that assessments of virus shedding show a higher degree of infection by rhinovirus in Introverts than they do in Extroverts. The influenza trials however did not show such an effect. In addition, people with higher scores on a widely used self-report inventory of mild psychoneurotic symptoms tended to show more evidence of increased nasal secretion after infection by either type of virus. The specific scale showing the latter effect most clearly was that of Obsessional Symptoms. Taking account of these psychological factors greatly increased the sensitivity of a study of the beneficial effects of interferon.

Antibodies, Viral↗
PubMed1984

Performance and its measurement.

Performance involves numerous sub-functions, and cannot be treated as a unit. Several attempts have been made to separate functions impaired by different classes of drug: for example, high (monitoring) vs lower (performing) levels of function, early (perceptual) vs later (motor) functions, and strategic vs executive functions. The practical implications are that one cannot predict effects of a drug from a single performance test. One must either simulate the practical situation exactly, or use a battery of analytical tests to form a profile of effects. The latter is the policy urged in this paper.

Amphetamine↗