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J Burkell

Publications and source records attributed to J Burkell.

4 recordsLinked to original sources
PubMed1996

A critique of an evaluation of the impact of hospital bed closures in Winnipeg, Canada: lessons to be learned from evaluation research methods.

In the last few years, the continuing increases in health care expenditures have led to a call for greater accountability in health care and have spurred evaluative research into the area of health care policy. Yet the challenge has been to develop health care policy evaluations that maximize the rigor of the evaluation process within the constraints and limitations of evaluation milieus. This paper describes the principles of evaluation research and, using the example of a study evaluating the impact of hospital bed closures on community health status in Winnipeg, Canada, demonstrates the epistemological, methodological and interpretive problems that can occur when these principles are not followed. The conclusions are that studies which fail to outline the causal links between policy actions and outcomes, and use designs and methods which threaten internal and external validity, are limited in their abilities to elucidate the impact of health care policy changes.

Health Expenditures↗
PubMed1994

Multiple parallel access in visual attention.

It is widely accepted that there exists a region or locus of maximal resource allocation in visual perception--sometimes referred to as the spotlight of attention. We have argued that even if there is a single locus of processing, there must be multiple loci of parallel access--several places in the visual field must be indexed at once and these indexes can be used to determine where attention is allocated. We have carried out a variety of studies to support these ideas, including experiments showing that subjects can track multiple independent moving targets in a field of identical distractors, that the enhanced ability to detect changes occurring on these targets does not accrue to nontargets nor to items lying inside the convex polygon that they form (so that a zoom-lens of attention does not fit the data). We have used a visual search paradigm to show that (serial or parallel) search can be confined to a subset of indexed items and the layout of these items is of little importance. We have also studied the phenomenon known as subitizing and have shown that subitizing occurs only when items can be preattentively individuated and in those cases location precuing has little effect, compared with when counting occurs, which suggests that subitizing may be carried out by counting active indexes rather than items in the visual field. And finally we have run studies showing that a certain motion effect that is sensitive to attention can occur at multiple precued loci. We believe that this evidence suggests that there is an early preattentive stage in vision where a small number of salient items in the visual field are indexed and thereby made readily accessible for a variety of visual tasks.

Attention↗
PubMed1983

The cost of visual filtering.

Speeded choice responses (reading or naming) to a relevant stimulus under conditions of spatial uncertainty are delayed by the simultaneous occurrence of other events. This "filtering cost" occurs despite high discriminability of target and distractors, which allows parallel detection of the target in search through the same displays. Reading is also delayed when the removal of irrelevant objects from the field coincides with the onset of the target. Filtering costs are caused by the processing of events rather than by the mere presence of irrelevant items. They are eliminated by advance information about the location of the target or by advance presentation of maintained distractors.

Adolescent↗