PubMed Health⌕ Search

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 253 records · Page 14Linked to original sources
PubMed1995

The N400 as a function of the level of processing.

In a semantic priming paradigm, the effects of different levels of processing on the N400 were assessed by changing the task demands. In the lexical decision task, subjects had to discriminate between words and nonwords, and in the physical task, subjects had to discriminate between uppercase and lowercase letters. The proportion of related versus unrelated word pairs differed between conditions. A lexicality test on reaction times demonstrated that the physical task was performed nonlexically. Moreover, a semantic priming reaction time effect was obtained only in the lexical decision task. The level of processing clearly affected the event-related potentials. An N400 priming effect was only observed in the lexical decision task. In contrast, in the physical task a P300 effect was observed for either related or unrelated targets, depending on their frequency of occurrence. Taken together, the results indicate that an N400 priming effect is only evoked when the task performance induces the semantic aspects of words to become part of an episodic trace of the stimulus event.

Adult↗
PubMed2000

Vocal control of acoustic information for sonar discriminations by the echolocating bat, Eptesicus fuscus.

This study aimed to determine whether bats using frequency modulated (FM) echolocation signals adapt the features of their vocalizations to the perceptual demands of a particular sonar task. Quantitative measures were obtained from the vocal signals produced by echolocating bats (Eptesicus fuscus) that were trained to perform in two distinct perceptual tasks, echo delay and Doppler-shift discriminations. In both perceptual tasks, the bats learned to discriminate electronically manipulated playback signals of their own echolocation sounds, which simulated echoes from sonar targets. Both tasks utilized a single-channel electronic target simulator and tested the bat's in a two-alternative forced choice procedure. The results of this study demonstrate changes in the features of the FM bats' sonar sounds with echolocation task demands, lending support to the notion that this animal actively controls the echo information that guides its behavior.

Animals↗
PubMed2004

Face-gender discrimination is possible in the near-absence of attention.

The attentional cost associated with the visual discrimination of the gender of a face was investigated. Participants performed a face-gender discrimination task either alone (single-task) or concurrently (dual-task) with a known attentional demanding task (5-letter T/L discrimination). Overall performance on face-gender discrimination suffered remarkably little under the dual-task condition compared to the single-task condition. Similar results were obtained in experiments that controlled for potential training effects or the use of low-level cues in this discrimination task. Our results provide further evidence against the notion that only low-level representations can be accessed outside the focus of attention.

Adult↗
PubMed1999

Depressed mood in multiple sclerosis: relationship to capacity-demanding memory and attentional functioning.

Because it is theorized that depression results in reduced available attentional capacity that, in turn, can explain the impaired performance on capacity-demanding tasks in depressed individuals, the authors predicted that multiple sclerosis (MS) patients with depressed mood would have difficulty with these types of tasks. Twenty depressed mood MS participants were compared with 41 nondepressed mood MS participants and 8 nondepressed mood controls on 5 attentional capacity-demanding clinical memory and attentional tasks and 3 tasks with minimal capacity demands. Depressed mood MS patients performed significantly worse than both nondepressed mood groups on the 3 speeded capacity-demanding attentional measures but not on any of the tasks requiring few capacity demands, supporting the authors' predictions. The possibility that the impaired performance of depressed mood MS patients on speeded attentional tasks was mediated by reduced verbal working memory capacity, impaired deployment of executive strategies that access working memory capacity, or psychomotor slowing is explored.

Attention↗
PubMed1983

[Development of demands with increasing technology in text processing].

Text-processing task demands are inquired about by means of an Ergonomic Job Description Questionnaire. The tasks are related to 5 steps of technologies and demands are documented for each of the technologies. With increasing technology demands on visual perception and work organisation dominate, while some demands on energetic work and environmental conditions decrease.

Computers↗
PubMed2026

The asymmetry of working memory training transfer: A systematic review and meta-analysis.

Working memory (WM) training is widely used to enhance cognitive performance; however, its transfer to untrained tasks remains controversial. Traditional theories emphasize task similarity as the primary determinant of training transfer, but they cannot fully explain emerging evidence of asymmetric transfer across tasks. Two directional transfer hypotheses are proposed here to explain this asymmetry: the resource-based transfer advantage hypothesis predicts stronger transfer from more to less cognitively demanding tasks, whereas the ability-based transfer advantage hypothesis predicts stronger transfer from tasks engaging broader task-general abilities to tasks engaging task-specific narrower abilities. The contrast between span and updating paradigms provides an informative framework for distinguishing these accounts, because updating tasks are generally more cognitively demanding, whereas span tasks involve broader abilities. Accordingly, we conducted a three-level meta-analysis of 55 studies (208 effect sizes; N = 3,492). The results showed that updating training transferred reliably to span tasks (g = 0.176, p < .001), whereas span training did not reliably transfer to updating tasks (g = 0.048, p = .453), supporting the resource-based account. This advantage of updating training also extended to non-WM outcomes and was more pronounced at lower training doses, in non-adult samples, and with verbal stimuli. Together, these findings extend WM transfer theory beyond task similarity by highlighting the importance of cognitive demand and offer guidance for WM training design.

Humans↗
PubMed1997

Stability of reach-to-grasp movement patterns in Parkinson's disease.

The performance of patients with Parkinson's disease on two reach-to-grasp tasks was compared with that of age-matched control subjects. The aim of the study was to determine whether Parkinson's disease patients have problems coordinating concurrently executed tasks within the same system of effectors in a natural context and whether such problems would be exacerbated by increases in task difficulty. We examined how subjects concurrently executed the transport and grasp components of reach-to-grasp movements in the presence of two types of change in task demands: (i) increases in demands for accurate digit pad placement and (ii) use of two reach-to-grasp tasks, i.e. the standard unimanual task and a bimanual task which increased the control and coordination demands relative to the unimanual task. If Parkinson's disease patients have coordination problems they should demonstrate increased impairment with increasing accuracy demands and in the bimanual task; any such differences should be absent or much smaller in the control group. The Parkinson's disease group showed substantial impairments in all conditions, moving about 30% slower than the control group, with much increased jerking and with signs of difficulty controlling the speed of movement. However, there were no consistent indications that the Parkinson's disease group were differentially impaired on the bimanual task nor that movement deficits increased with increasing accuracy requirements. Grasp and transport components were coordinated similarly by Parkinson's disease and control groups in both reach-to-grasp tasks, and the Parkinson's disease group co-ordinated the two limbs in the bimanual task effectively and in a fashion similar to that of the control group. These results are interpreted to mean that higher levels (effector-independent levels) of motor programming are preserved in Parkinson's disease and that execution of a motor programme need not be compromised by increasing the number of muscle-/joint-level degrees of freedom which are used.

Aged↗
PubMed2002

Dissociation in human prefrontal cortex of affective influences on working memory-related activity.

Although neural activity associated with emotion is becoming better understood, the influence of affective parameters on brain activity reflecting cognitive functioning in humans remains poorly characterized. We examined affective influences on working memory (WM) and tested the hypotheses that (i) dorsolateral prefrontal cortex (DLPFC) activity reflecting WM is influenced by the emotion-evoking qualities of task-relevant stimuli, but only when brought "on-line" by task demands, and (ii) DLPFC and orbitofrontal cortex (OFC) activities are inversely related as a function of emotional valence. Participants performed two tasks while event-related functional MRI measured brain activity; one task required active maintenance of stimulus representations in WM, and the other task required target detection responses with no demand for WM. Stimuli were standardized emotional (pleasant and unpleasant) and neutral pictures. Emotional stimuli differentially influenced DPFC and OFC activity during WM; DLPFC was influenced by emotional valence, enhanced by pleasant and reduced by unpleasant, compared to neutral stimuli, only when task conditions required WM. OFC was valence-sensitive during both tasks, greater to arousing than neutral stimuli when WM demand was low and in inverse relationship to DLPFC with high WM demand. Further, DLPFC and OFC activities are inversely related with respect to emotional valence during the WM task. The results are consistent with the hypothesis that the intrinsic valence of task-relevant stimuli maintained in WM modulates DLPFC activity but only when the DLPFC is required for task demands. Findings suggest a conceptualization of DLPFC and its involvement in WM that takes into account a role for affective parameters.

Adult↗
PubMed2003

Trunk recruitment during spoon use in tetraparetic cerebral palsy.

In the present study we investigated the extent to which individuals suffering from spastic tetraparesis as a consequence of cerebral palsy tune their trunk involvement to accuracy demands in a spoon-handling task. Twenty-two participants (ten adolescents with spastic tetraparesis and 12 control participants) had to transport a spoon filled with water or sugar to a small or a large bowl that was placed within reach. Even though trunk displacement was larger in the tetraparetic participants than it was in the control participants, the effects of the imposed accuracy constraints were remarkably similar. Participants in both groups increased trunk displacement with increasing precision requirements. Furthermore, in both groups the largest trunk involvement was found in the initial and final part of the substance-transporting phase, when wrist velocity was lowest. We propose several explanations for these findings and conclude that the large trunk involvement in individuals with tetraparetic cerebral palsy should, in any case, not be regarded as a primary symptom of the disorder, but rather as an adaptive reaction to increased task demands.

Adolescent↗
PubMed1975

An alternative approach to dose reduction in dental radiography.

A responsible approach to dose reduction in dental radiography requires that relative exposure be related to the specific diagnostic task performed. All but the most demanding tasks can be performed when suitable film is used in conjunction with high-speed screens. Placing the source of radiation inside the mouth permits radiographic information to be recorded on an improved Polaroid cassette that has a relatively high quantum efficiency. As a result, the radiation dose can be significantly reduced in a versatile system which provides for instantaneous processing and interpretation from prints rather than negatives.

Radiation Dosage↗
PubMed2004

Parametric study of accuracy and response time in schizophrenic persons making visual or auditory discriminations.

The inability to modulate processing time in conjunction with varying difficulty levels may be a core component of schizophrenia's cognitive deficit. In this study we used a parametric design to demonstrate this group's inability to increase and decrease response times in association with varying levels of task demand during auditory and visual recognition tasks. Unlike participants with schizophrenia, healthy volunteers responded to increasing levels of difficulty and high error by robustly increasing their average response times. In the group with schizophrenia, the greater the correlation between a subject's Response-Time and error rate the better was the subject in his/her overall discrimination accuracy. The higher their correlations the better they performed across all levels of difficulty in both modalities. The schizophrenia group's tendency to process high and low error conditions with similar behavioral resources may reflect a relatively static, non-dynamic cognitive repertoire.

Adult↗
PubMed1992

Verbal fluency and positron emission tomographic mapping of regional cerebral glucose metabolism.

Impairment in verbal fluency (VF) has been a consistently reported clinical feature of focal cerebral deficits in frontal and temporal regions. More recent behavioral activation studies with healthy control subjects using positron emission tomography (PET), however, have noted a negative correlation between performance on verbal fluency tasks and regional cortical activity. To see if this negative relationship extends to steady-state non-activation PET measures, thirty-three healthy adults were given a VF task within a day of their 18F-2-fluoro-2-deoxy-D-glucose PET scan. VF was found to correlate positively with left temporal cortical region metabolic activity but to correlate negatively with right and left frontal activity. VF was not correlated significantly with right temporal cortical metabolic activity. Some previous studies with normals using behavioral activation paradigms and PET have reported negative correlations between metabolic activity and cognitive performance similar to that reported here. An explanation for the disparate relationships that were observed between frontal and temporal brain areas and VF might be found in the mediation of different task demands by these separate locations, i.e., task planning and/or initiation by frontal regions and verbal memory by the left temporal area.

Adult↗
PubMed1997

Response learning of rats in a Morris water maze: involvement of the medical prefrontal cortex.

This study is concerned with the question whether the medial prefrontal cortex mediates spatial navigation requiring the expression of response learning. It consists of two parts. In the first experiment it was investigated whether intact male Wistar rats can learn a spatial response task in a Morris water maze, and, if so, how the learning of this task compares with the learning of a place task, in the same water maze. The data illustrate that rats can indeed learn the response task demands, but also demonstrate that this task is more difficult to learn than the place task. This is evidenced by a slower and more capricious acquisition. Based on these findings a second experiment was conducted, in which sham-operated rats and rats with damage of the medial prefrontal cortex (mPFC) were compared for their acquisition in the response task in the Morris water maze. The results showed that both escape latency and path length of the mPFC-damaged animals were significantly higher than those of the sham-operated animals. A behavioral analysis of the swimming paths demonstrated that the mPFC-damaged rats were more persistent in their use of a place strategy, while the sham-operated animals sooner switched to the more successful taxon-orientation strategy. Taken together with previous findings these data support the hypothesis of a functional dissociation of the mPFC with regard to its involvement in the expression of place and response learning.

Animals↗
PubMed2003

Which clinical decisions benefit from automation? A task complexity approach.

OBJECTIVE: To describe a model for analysing complex medical decision making tasks and for evaluating their suitability for automation. METHOD: Assessment of a decision task's complexity in terms of the number of elementary information processes (EIPs) and the potential for cognitive effort reduction through EIP minimisation using an automated decision aid. RESULTS: The model consists of five steps: (1) selection of the domain and relevant tasks; (2) evaluation of the knowledge complexity for tasks selected; (3) identification of cognitively demanding tasks; (4) assessment of unaided and aided effort requirements for this task accomplishment; and (5) selection of computational tools to achieve this complexity reduction. The model is applied to the task of antibiotic prescribing in critical care and the most complex components of the task identified. Decision aids to support these components can provide a significant reduction of cognitive effort suggesting this is a decision task worth automating. CONCLUSION: We view the role of decision support for complex decision to be one of task complexity reduction, and the model described allows for task automation without lowering decision quality and can assist decision support systems developers.

Artificial Intelligence↗
PubMed2000

The development of children's knowledge of attention and resource allocation in single and dual tasks.

Developmental changes in kindergarten, 1st-, and 4th-grade children's knowledge about the variables that affect attention sharing and resource allocation were examined. Findings from the 2 experiments showed that kindergartners understood that person and strategy variables affect performance in attention-sharing tasks. However, knowledge of how task variables affect performance was not evident to them and was inconsistent for 1st and 4th graders. Children's knowledge about resource allocation revealed a different pattern and varied according to the dissimilarity of task demands in the attention-sharing task. In Experiment 1, in which the dual attention tasks were similar (i.e., visual detection), kindergarten and 1st-grade children did not differentiate performance in single and dual tasks. Fourth graders demonstrated knowledge that performance on a single task would be better than performance on the dual tasks for only 2 of the variables examined. In Experiment 2, in which the dual attention tasks were dissimilar (i.e., visual and auditory detection), kindergarten and 1st-grade children demonstrated knowledge that performance in the single task would be better than in the dual tasks for 1 of the task variables examined. However, 4th-grade children consistently gave higher ratings for performance on the single than on the dual attention tasks for all variables examined. These findings (a) underscore that children's meta-attention is not unitary and (b) demonstrate that children's knowledge about variables affecting attention sharing and resource allocation have different developmental pathways. Results show that knowledge about attention sharing and about the factors that influence the control of attention develops slowly and undergoes reorganization in middle childhood.

Attention↗
PubMed2002

Expertise, attention, and memory in sensorimotor skill execution: impact of novel task constraints on dual-task performance and episodic memory.

Two experiments explored the attention and memory processes governing sensorimotor skill. Experiment 1 compared novice and experienced golf putting performance in single-task (putting in isolation) and dual-task conditions (putting while performing an auditory word search task). At specific intervals, participants also produced episodic descriptions of specific putts. Experiment 2 assessed novice performance following training on the same putting task. In Experiment 1, experienced golfers did not differ in putting accuracy from single-to dual-task conditions and, compared to novices, had higher recognition memory for words heard while putting but diminished episodic memories of specific putts. However, when using an s-shaped arbitrarily weighted "funny putter" designed to disrupt the mechanics of skill execution, experienced golfers produced extensive episodic memories of specific putts but showed decreased dual-task putting accuracy and recognition memory for secondary task words. Trained novices produced results intermediate between the untrained novices and experienced golfers. As predicted by current theories of practice-based automaticity, expertise leads to proceduralized control that does not require constant attention. Resources are free to devote to secondary task demands, yet episodic memory for primary task performance is impoverished. Novel task constraints (e.g., a funny putter) increase attention to execution, compromising secondary task performance but enhancing memory for skill execution.

Attention↗
PubMed2004

Prefrontal-subcortical dissociations underlying inhibitory control revealed by event-related fMRI.

Using event-related fMRI, this study investigated the neural dynamics of response inhibition under fluctuating task demands. Fourteen participants performed a GO/NOGO task requiring inhibition of a prepotent motor response to NOGO events that occurred as part of either a Fast or Slow presentation stream of GO stimuli. We compared functional activations associated with correct withholds (Stops) required during the Fast presentation stream of stimuli to Stops required during the Slow presentation stream. A predominantly right hemispheric network was activated across conditions, consistent with previous studies. Furthermore, a functional dissociation of activations between conditions was observed. Slow Stops elicited additional activation in anterior dorsal and polar prefrontal cortex and left inferior parietal cortex. Fast Stops showed additional activation in a network that included right dorsolateral prefrontal cortex, insula and dorsal striatum. These results are discussed in terms of our understanding of the impact of preparation on the distributed network underlying response inhibition and the contribution of subcortical areas, such as the basal ganglia, to executive control processes.

Adult↗