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Biomedical subjects

M H Broadbent

Publications and source records attributed to M H Broadbent.

8 recordsLinked to original sources
PubMed1990

Human attention: the exclusion of distracting information as a function of real and apparent separation of relevant and irrelevant events.

A leading theory suggests that human vision operates by separate and parallel analysis of each of the simple features of the visual scene; but computation of the identity of objects, which needs combination of these features, is undertaken selectively and only for some parts of the incoming information. It is known that the identity of distracting events affects reaction time only for distractors spatially close to the reaction signal. This suggests that the selection is spatially based; perhaps taking place in the projection areas. Experiments on this topic have, however, normally considered events only at a fixed viewing distance; in this study different viewing distances were employed. It was found that, over the range of conditions used, the ability to exclude irrelevant distractors depended upon the true physical separation and not on the angular separation at the eye of the observer. Hence the 'attention' system must operate at a point later than the computation of true physical location, rather than at the very early stage where angular separation only is available.

Attention↗
PubMed1986

Encoding speed of visual features and the occurrence of illusory conjunctions.

Earlier studies have found that people show characteristic errors when asked to observe a rapid stream of events and to name the colour of a certain letter, or the letter in a certain colour. They tend to report the letter or colour from an event later in time than the correct one. This is not true, however, if they are asked to name the colour of a digit amongst letters, without knowing in advance the identity of the digit. There is also some evidence that the errors are symmetric if the location of the target is not known in advance. Three experiments are reported which show that this symmetry results from slow encoding of the colour as compared with the digit. It is still true that uncertainty about target identity does reduce the tendency to see the target in a later than an earlier colour. This effect is, however, superimposed on asymmetries resulting from coding speed, and the effect of uncertainty of location may be due only to this.

Color Perception↗
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

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↗
PubMed1980

Modality differences in relation to grouping in immediate recall.

An earlier study of auditory grouped presentation of digit strings had shown recall to be impaired by recalling the last group first. From this, it has been concluded that the item codes formed at Stage 1 of processing, and before conversion to a group code at Stage 2, were not yet in an output buffer. The present paper employs visual presentation for two similar studies, with results opposite to the earlier one; in a third experiment, ungrouped auditory stimulation gave results which were a compromise between those for vision and those for grouped auditory stimulation. These results suggest a use of echoic storage, over long intervals; in the visual case this is not so and an output buffer is employed.

Adult↗