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Biomedical subjects

A F Sanders

Publications and source records attributed to A F Sanders.

16 recordsLinked to original sources
PubMed1992

Changing trends in treatment of substance abuse: a look at some of the factors involved in third-party providers and treatment planning.

In order to better focus our care in providing patients with treatment that matched their needs, an inpatient study was done on patient discharges for 1990 involving 267 patients. Our study points out the influence of the changing drug scene in this country. In approximately 40% of the patients admitted, the drug of choice is other than alcohol. The importance of family and employer involvement in effective treatment stands out. Fewer patients are being admitted but those admitted are sicker and require more treatment. Chemical dependency programs in Louisiana and the United States are experiencing significant declines in the utilization of their service and many are closing. The patient census has been impaired primarily by the expense of or lack of insurance coverage by third-party payors. For patients with insurance coverage the criteria for inpatient treatment by third-party reviewers are so stringent that staff assessment recommendations are frequently over-ruled. Substance abuse is a chronic relapsing illness, yet many insurance companies limit coverage both in time and money. In no other field of medicine do patients leave treatment prematurely as they do in substance abuse.

Adult↗
PubMed1991

Perceptual processing and speed-accuracy trade-off.

Three experiments are described on speed-accuracy trade-off during a visual fixation. In a typical trial subjects started by fixating a fixed position at their left side at which a degraded digit (SL) was presented. At about the same time an intact digit (SR) was briefly presented at a fixed right side position. SL and SR were separated by a binocular visual angle of 45 degrees. The task was to verbally report both digits, which implied that the eyes should be rapidly shifted from SL to SR, so as not to miss SR. Under these conditions the distribution of the fixation latencies of SL appeared to consist of two parts, suggesting the occurrence of either anticipations or reactions. This argues against a strategy of optional stopping of information accrual during the fixation of SL and is in line with a strategy of either fully neglecting or fully encoding SL. However, this interpretation meets the difficulty that, at trials where SL is reacted to, subjects showed a shorter fixation latency than in a control condition, in which they had ample time to view both SL and SR. The results of the second and third study supported the view that, when under time stress, subjects can end a fixation as soon as a preliminary code of SL is obtained. This code (a) is insensitive to the complexity of SL, (b) cannot be elaborated during the saccade to SR, and (c) can be used as a starting point for further analysis, as soon as the eyes reach SR.

Achievement↗
PubMed1991

Simulation as a tool in the measurement of human performance.

The paper outlines and discusses issues in the present-day development and application of simulations of complex tasks. It is noted that this development is observed in basic as well as in applied research, resulting in a trend away from the investigation of elementary properties of human functioning in favour of the analysis of complete tasks. One of the problems in simulation concerns appropriate output measures (section 2). Some recent sophisticated measures of performance are derivatives of more elementary measures of time and accuracy, but they still facilitate new insights into the measurement of performance. In addition, recent views are discussed of verbal reports as potential measures of cognitive skills. It is noted that the issue of performance measurement has been severely neglected and ignored in many applications of simulators. The paper also focuses on theoretical models (section 3). It is concluded that models for complete tasks face the problem of excessive complexity, thus inhibiting detailed parametric analysis. In this respect the analysis of elementary properties has a clear advantage. A strategy of back-to-back experimentation, originally proposed by Gopher and Sanders (1984), is reiterated and an example of a back-to-back study is described. Section 4 of the paper is devoted to the issue of validation with major emphasis on the possibilities and limitations of the transfer paradigm and the measurement of direct correspondence. The final section (5) is devoted to some selective remarks about the three main areas where simulators are applied, namely training, equipment design, and personnel assessment. The paper ends by summarizing some emerging trends and issues for future research.

Computer Simulation↗
PubMed1990

Stratification in perception and action.

This paper discusses the concept of stratification, in the sense of levels of analysis and levels of control, in relation to human perception and performance. It is contended that functional analysis is the proper level of analysis for the domain of perception and action. This is illustrated by means of models of cognitive energetics and motor control. The functional level of analysis can be situated in between the level of symbolic representations and the level of neurophysiological mechanisms. It is also argued that the concept of levels of control provides a way of integrating or relating ecological and information-processing approaches to psychology, in the sense that ecological psychology is concerned with lower and more peripheral levels of control (coordinative structures). Finally, some remarks are made on the relation between cognition and perception and action, drawing on Piaget, and it is proposed that the concept of schema is more appropriate for the domain of perception and action than is the notion of symbolic representations.

Attention↗
PubMed1989

Resources and dual-task performance; resource allocation versus task integration.

This study aims at contributing to the explanation of dual-task performance in terms of either resource allocation or of task interference and integration. Twenty-four subjects carried out, single and in combination, a motor interval production task and a perceptual target detection task on the basis of combined memory and display search. The demands of the target detection task were varied by increasing or decreasing the presentation rate of successive search displays. Furthermore, the presentation rate was either constant or variable. The dual-task condition had a negative effect on interval production, the extent of which was unaffected by either rate or variability of display presentation. This means that there was no evidence for synchronizing interval production with display presentation, so that the major opportunity for task integration did not substantiate. It is suggested that the two tasks use different resource pools in addition to a common mechanism, the limited capacity of which causes a general interference in dual-task conditions.

Adolescent↗
PubMed1988

Drugs and information processing in skilled performance.

A concise review is presented of recent research on task aspects with respect to determining the effects of drugs on human information processing. It is concluded that progress in this area is hampered by lack of a theoretical basis to most behavioral tasks, preventing firm conclusions about the effects of drugs on either well-defined mental functions or on real-life performances. It is argued that the effects of drugs should only be tested in behaviorally well-researched tasks. Some proposals are discussed with an emphasis on perceptual-motor skills.

Humans↗
PubMed1975

Some effects of ACTH 4-10 on performance during a serial reaction task.

Eighteen subjects worked continuously for half an hour in a self-paced reaction task. Half of the subjects were injected with ACTH 4-10 (30 mg/s.c.) and the other half with a placebo. The subjects injected with ACTH 4-10 showed a larger improvement in reaction time during the experimental session than the placebo group. However, this effect disappeared in a short retest, which was given half an hour after the experimental session. These results suggest that ACTH 4-10 has no effect on skill acquisition, but counteracts the build-up of reactive inhibition during the experimental session; that is, the peptide suppresses the decrease in motivation, which usually occurs during continuous performance tasks. This notion is confirmed by an analysis of the frequency distributions of the reaction times. Treatment effects were only found for the long reaction times. Long reaction times tend to occur with increasing frequency as a function of time-on-task and are an indication for the level of motivation of the subject. It was concluded that ACTH 4-10 counteracts the usual decay in performance as a function of time-on-task due to increasing boredom and mental fatigue.

Adrenocorticotropic Hormone↗