SEARCH · PubMed Health

Results for “Task demands”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 541 records · Page 30Linked to original sources

PubMed2004

Preserved obstacle avoidance during reaching in patients with left visual neglect.

We asked 12 patients with left visual neglect to bisect the gap between two cylinders or to reach rapidly between them to a more distal target zone. Both tasks demanded a motor response but these responses were quite different in nature. The bisection response was a communicative act whereby the patient indicated the perceived midpoint. The reaching task carried no imperative to bisect the gap, only to maintain a safe distance from either cylinder while steering to the target zone. Optimal performance on either task could only be achieved by reference to the location of both cylinders. Our analysis focused upon the relative influence of the left and right cylinders on the lateral location of the response. In the bisection task, all neglect patients showed qualitatively the same asymmetry, with the left cylinder exerting less influence than the right. In the reaching task, the neglect group behaved like normal subjects, being influenced approximately equally by the two cylinders. This was true for all bar two of the patients, who showed clear neglect in both tasks. We conclude that the visuomotor processing underlying obstacle avoidance during reaching is preserved in most patients with left visual neglect.

Aged↗

PubMed2004

Transient inactivation of the rat nucleus accumbens does not impair guidance of instrumental behaviour by stimuli predicting reward magnitude.

The involvement of the nucleus accumbens (NAc) in the determination of reaction times (RTs) of instrumental responses by the expectancy of future reward was investigated. A simple RT task demanding conditioned lever release was used, in which the upcoming reward magnitude (5 versus 1 pellet) was signalled in advance by discriminative cues. In rats which acquired the task, RTs of instrumental responses were significantly shorter to the discriminative cue predictive of high reward magnitude. Inactivation of the NAc by lidocaine had no effect on RTs and their determination by cue-associated reward magnitudes, and did not affect the rate of correct responses. In keeping with an earlier study, intra-NAc infusion of amphetamine decreased RTs, impaired RT determination by cue-associated reward magnitudes and reduced the rate of correct responses. The unexpected finding that lidocaine inactivation of the NAc had no effect parallels previous data showing that lesions of NAc did not impair RT performance, while manipulation of intra-NAc glutamate or dopamine transmission impaired various aspects of RT performance in comparable tasks. It is suggested that experimental manipulations such as transient and permanent inactivation, which almost completely inhibit NAc neuronal output, allow alternative routes to be used to effectively control behaviour in the task employed here.

Animals↗

PubMed1981

Inferotemporal neurons distinguish and retain behaviorally relevant features of visual stimuli.

Single-cell activity was recorded in the inferotemporal cortex of monkeys performing a task that requires perception and temporary retention of colored stimuli. Many cells reacted differentially to the stimuli. By changing the relevance of certain features of compound stimuli, it was found that the reactions of some cells to color depend critically on whether or not the task demands that the animal pay attention to color. A substantial number of cells showed color-dependent differences in frequency of discharge during the retention periods of the task. The temporal characteristics of differential discharge and its dissolution when memory is no longer required indicate that the cells that display it are involved in retaining visual information.

Action Potentials↗

PubMed2001

Cognitive performance and muscle activation in workers with chronic shoulder myalgia.

The present study determined whether workers with chronic shoulder myalgia exhibit impaired cognitive performance and elevated muscle activation. Ten workers with and 10 without shoulder myalgia performed three sessions, each consisting of three different cognitive tasks. Subjective pain was reported on visual analogue scales (VAS). Surface electromyography was recorded bilaterally from the trapezius and forearm extensor muscles. Speed and error rates of the cognitive work were almost the same in the two groups, but the myalgia subjects reported more stress during the work. In two of the cognitive tasks, both groups increased their speed of performance to the same extent from the first to the third session, despite pain increase in the myalgia subjects. In the biomechanically demanding task, the speed fell from the first to the third session in both groups. Muscle activation was equal in the two groups and constant throughout the protocol despite changes in speed of performance and pain. It is concluded that localized chronic muscle pain does not significantly alter cognitive performance, or muscle activation level during cognitive work. However, the perceived burden of work is larger, as indicated by the higher stress reported during cognitive work in the myalgia subjects compared with their pain-free controls.

Chronic Disease↗

PubMed2003

Abnormal sequencing of motor actions in patients with schizophrenia: evidence from grip force adjustments during object manipulation.

OBJECTIVE: During object manipulation, grip force must be adjusted in anticipation of destabilizing load forces to prevent the object from slipping. This study used three gripping tasks to assess whether schizophrenia affects the predictive mechanisms required for the scaling, timing, and/or sequencing of motor actions. METHOD: Sixteen patients with schizophrenia and 16 comparison subjects matched for age, sex, and educational level 1) lifted objects of various mass and texture (lift task) and 2) used a manipulandum to hit (hit task) or resist (resist task) impacts produced by a collision with a pendulum. For an optimized performance, all tasks demanded a predictive increase in grip force and the timing of external events. The fluid sequencing of finger and hand submovements was required for the lift and the hit tasks but not for the resist task. RESULTS: Patients were impaired in the smooth execution of both the lift and the hit tasks but not in the performance of the resist task. In all three tasks, the scaling of grip force was similar for patients and comparison subjects. CONCLUSIONS: Schizophrenia is associated with a specific deficit in the sequencing of motor actions rather than with an overall problem in the predictive control of movement.

Adolescent↗

PubMed2000

[The influence of verbal encoding on the memory of visual information].

The previous research which investigated the effect of verbal encoding on the memory of visual information has yielded contradictory results: facilitation and inhibition of performance by verbal encoding. However, it has not been elucidated why and how these conflicting results were brought about. The main purpose of this study is to show that verbal encoding not only facilitates but also impairs performance by taking task demand and characteristics of visual representations into account. Another purpose is to investigate how verbal encoding would influence the memory of color information, which is irrelevant for the memory task. In Experiment 1, the results showed that verbal encoding could have two opposite effects in the same task. In Experiment 2, the results showed that the effect of verbal encoding on the memory of color would differ from that on the memory of the shapes of pictures.

Adult↗

PubMed1991

Auditory attention switching: a developmental study.

The developmental course of the ability to rapidly allocate attention was studied using a dichotic listening task with 8-year old, 11-year old and college age subjects. In this task, subjects were instructed to listen to one ear for predescribed targets and then were later signaled (on some trials) to switch their attention to the other ear. Reorientation was assessed by comparing the pattern of subjects' omission and intrusion errors on trials following a command to switch ears with the pattern of errors on no-switch trials. Older subjects were better able to reallocate their attention in accordance with task demands, with the greatest gains in performance occurring between ages 8 and 11. This developmental change appears to be generally continuous and quantitative in nature. Since successful performance of this task requires flexibility in subjects' ability to control their focus of attention, these results support the hypothesis that the basis of the developmental improvement in the ability to ignore irrelevant information is linked to the ability to use active attentional strategies.

Adolescent↗

PubMed2004

Differential effects of active and passive stress on food intake in restrained and unrestrained eaters.

This study examined the effects of active (AC) and passive coping (PC) stress tasks on food intake in female restrained (n = 20) and unrestrained eaters (n = 20) Participants completed a reaction time task (AC), a cold-pressor test (PC), and a relaxation control condition separated by 1-week intervals. Food intake was assessed after each task. Self-reported anxiety, heart rate and blood pressure (BP) were measured before and after each task. Restraint was measured using the Dutch Eating Behaviour Questionnaire. Significant increases in BP were evident in the AC task only. Stress tasks produced significant increases in self-rated anxiety. Restrained eaters consumed more than unrestrained following the reaction time task, while the opposite was observed following relaxation. The findings of this study show that disinhibited eating of restrained eaters can be triggered by the distracting effects of a cognitively demanding task and may be independent of anxiety experienced.

Adaptation, Psychological↗

PubMed1999

Neglect without extinction.

A patient, AB, is reported who showed clear signs of neglect but no extinction (N+ E-). Several hypotheses proposed to account for this dissociation were put to the test. The postulated association between motor neglect and extinction did not hold good, nor did the possibility that the N+ E- dissociation may be traced back to the difference in test requirements and therefore observed only in patients with object-centred neglect. Likewise, manipulating the physical features of the stimuli (relative size, exposure time, presentation synchrony) did not elicit extinction. However, when the task demands were modified by asking the patient to perform a further spatial analysis of the stimuli, rather than simply detect them, extinction emerged. Since AB performed well on several neglect tasks requiring parallel processing, while failing all tasks calling for serial processing, the hypothesis is put forward that AB's N+ E- dissociation could be interpreted within the parallel/serial distinction framework.

Aged↗

PubMedDate not supplied

Knowing what the others know: a study on interprofessional communication between nurses and medical doctors.

Communication and cooperation between experts from different specialties is a necessary element of professional competence. We have set up a research program to investigate cognitive aspects of interprofessional and interdisciplinary communication. We assume that successful communication essentially relies on communicants' ability to take the perspective of the other, i.e., assessing the background knowledge, expertise, plans, and so on, of one's co-communicators. The present paper reports on an interview study with medical doctors and nurses from three paediatric oncology units. The research interview was especially designed to allow for a detailed assessment of the professionals' ability to take their work-partners' perspective. Two areas will be examined: The ability to assess the work demands resulting from parental questions, and the use of differences in professional perspectives for prognosis. With respect to parental questions, doctors' and nurses' assessments of their respective work partner's task demands turned out to be only partly correct. Furthermore, the results suggest that doctors do not effectively benefit from nurses' experiential knowledge about patients when venturing prognoses. Educational measures designed to improve interprofessional communication could help to overcome these deficits.

Child↗

PubMed1998

Learned industriousness: replication in principle.

Undergraduate students completed a series of training tasks consisting of solving anagrams, performing addition problems, and making perceptual discriminations, to validate findings of learned industriousness. The group that received high-effort training was given difficult and demanding tasks, whereas the group that received low-effort training was given easy tasks. Controls were given no preliminary training activity. For the criterion task, all participants were provided with a series of pencil and paper mazes to complete. They were allowed to "pass" on whatever mazes they wished (they could progress to the next maze but could not return to any that had been passed). Participants who had received high-effort training passed on significantly fewer mazes than did those in the control and low-effort conditions, thus supporting the generality of effects of reinforced high effort.

Humans↗

PubMed2006

A preliminary analysis of self-control with aversive events: the effects of task magnitude and delay on the choices of children with autism.

When faced with a choice between two aversive events, a person exhibits self-control by choosing a smaller, more immediate aversive event over a larger, delayed aversive event. Task demands are often aversive to children with autism and other developmental disabilities. The purpose of this study was to evaluate behavioral sensitivity to differences in the amount and delay of tasks as part of a preliminary study on self-control. Participants were 2 children with autism who engaged in problem behavior maintained by escape. Results indicated a lack of self-control with respect to choosing between two aversive tasks and suggested potential strategies for increasing self-control (i.e., choosing a small immediate task over a large delayed task).

Attention Deficit and Disruptive Behavior Disorder↗

PubMed1998

An integrative conceptual framework for assessing and treating suicidal behavior in adolescents.

Suicidal adolescents represent a uniquely demanding clinical population. Regardless of psychotherapeutic orientation, the existing standards of care demand a relatively broad and integrative approach with multiple and specific treatment targets, as well as ongoing and repeated risk assessment. The current article provides an integrative conceptual framework for these tasks in day to day clinical practice with essentially two goals: (1) to provide a summary of therapeutic and assessment tasks (i.e. the content of therapy and assessment) consistent with existing standards of care and supported by empirical findings, and (2) to emphasize the varied roles, tasks, demands and limitations of psychotherapy with suicidal adolescents.

Adolescent↗

PubMed2006

In-vehicle workload assessment: effects of traffic situations and cellular telephone use.

PROBLEM: Assessment of drivers' on-road workload is an important traffic safety consideration. This study was conducted to examine the effects of cellular phone communication on driving performance, with particular emphasis on variations in task demand in different traffic situations. METHOD: Twelve participants were asked to drive on urban roads and motorways with or without concomitant mathematical-addition tests relayed via cellular phone. Measurements included task and driving performance, physiological responses, and compensatory behavior. RESULTS: Analysis of task performance revealed that mean response time was markedly increased (11.9%) for driving on urban roads compared to motorways. The mean driving speed only decreased 5.8% in the presence of phone tasks in comparison to normal driving without distractions. In addition, overall physiological workload increased through compensatory behavior in response to the phone tasks. CONCLUSIONS: Driving with phone use in different traffic environments induced measurable variations in driver workload. IMPACT ON INDUSTRY: When faced with heavy traffic, a greater safety margin is typically adopted, with more lowered driving speed and restricted phone use, and it can be assumed that there is a general trade-off between tasks to preserve driving safety.

Adult↗

PubMed2006

Changing channels: an fMRI study of aging and cross-modal attention shifts.

Age-related deficits in visual selective attention suggest that the efficiency of inhibitory processes is particularly affected by aging. To investigate whether processing inefficiencies observed in visual attention are similar in auditory attention and when shifting attention across modalities, we conducted an fMRI study with healthy young and older adults using a task that required sustained auditory and visual selective attention and cross-modal attention shifts. Older adults in this study performed as well as the younger adults, but showed age-related differences in BOLD responses. The most striking of these differences were bilateral frontal and parietal regions of significantly increased activation in older adults during both focused and shifting attention. Our data suggest that this increased activation did not reflect new recruitment, but reliance on brain regions typically used by younger adults when task demands are greater. Older adults' activation patterns suggested that even during focused attention conditions they were "shifting" attention to stimuli in the unattended modality. Increased activation during processing of both task-relevant and task-irrelevant information implies age-related loss of processing selectivity. These patterns may reflect both task-specific compensatory neural recruitment and degradation of sensory inhibition.

Acoustic Stimulation↗

PubMedDate not supplied

Aging and feature search: the effect of search area.

The preattentive system involves the rapid parallel processing of visual information in the visual scene so that attention can be directed to meaningful objects and locations in the environment. This study used the feature search methodology to examine whether there are aging-related deficits in parallel-processing capabilities when older adults are required to visually search a large area of the visual field. Like young subjects, older subjects displayed flat, near-zero slopes for the Reaction Time x Set Size function when searching over a broad area (30 degrees radius) of the visual field, implying parallel processing of the visual display. These same older subjects exhibited impairment in another task, also dependent on parallel processing, performed over the same broad field area; this task, called the useful field of view test, has more complex task demands. Results imply that aging-related breakdowns of parallel processing over a large visual field area are not likely to emerge when required responses are simple, there is only one task to perform, and there is no limitation on visual inspection time.

Adult↗

PubMed2006

Task-irrelevant visual motion and flicker attenuate the attentional blink.

Our reduced ability to correctly report two sequentially presented targets is seen in the robust effect known as the attentional blink (AB; Raymond, Shapiro, and Arnell, 1992). One recent report (Olivers and Nieuwenhuis, 2005) strikingly reveals the AB to be virtually abolished when non-task-demanding music occurs in the background. The authors suggest that a diffuse attentional state is the mediating factor. Here, we seek to broaden the finding's generality by determining if task-irrelevant visual motion and flicker also attenuate the AB. In our experiments, the AB task was presented together with a background field of moving dots that could move away from or toward the central AB task, or flicker. In the control condition, the dots remained static. The AB was attenuated--though to different degrees--in all experimental conditions, but not in the static condition. Our findings add to the generality of the previous conclusions, and we emphasize an account based on the overallocation of attention.

Adult↗

PubMed2000

Expertise in women's gymnastic judging: an observational approach.

Observation was used to study expertise in gymnastic judging. 10 expert and 10 novice gymnastic judges were videotaped while judging at actual competitions. Analyses showed that novice judges, as compared to expert judges, spent less time looking at the gymnast perform, spent more time looking at the scoring paper, and were less able to engage in the dual-task demands required in gymnastic judging.

Achievement↗