Home About us Contact
|
Home About us Contact | ||
|
|
||
Task Demands (task + demand)
Selected AbstractsHistamine H1 receptor blockade predominantly impairs sensory processes in human sensorimotor performanceBRITISH JOURNAL OF PHARMACOLOGY, Issue 1 2009P Van Ruitenbeek Background and purpose:, Centrally active antihistamines impair cognitive performance, particularly sensorimotor performance. The aim of the present study was to further elucidate the scarcely studied subprocesses involved in sensorimotor performance, which may be affected by H1 receptor blockade. Better knowledge about the cognitive deficits associated with histamine dysfunction can contribute to better treatment of clinical disorders in which histamine hypofunction may be a contributing factor, such as in schizophrenia. Experimental approach:, Interactions of dexchlorpheniramine with specific task manipulations in a choice reaction time task were studied. Task demands were increased at the level of sensory subprocesses by decreasing stimulus quality, and at the level of motor subprocesses by increasing response complexity. A total of 18 healthy volunteers (9 female) aged between 18 and 45 years participated in a three-way, double-blind, crossover design. Treatments were single oral doses of 4 mg dexchlorpheniramine, 1 mg lorazepam and placebo. Behavioural effects were assessed by measuring reaction times and effects on brain activity by event-related potentials. Key results:, Dexchlorpheniramine significantly slowed reaction times, but did not significantly interact with task manipulations. However, it did significantly interact with stimulus quality, as measured by event-related potentials. Lorazepam slowed reaction times and interacted with perceptual manipulations, as shown by effects on reaction times. Conclusions and implications:, The results confirm that the histamine system is involved in sensory information processing and show that H1 blockade does not affect motoric information processing. Histamine hypofunction in clinical disorders may cause impaired sensory processing, which may be a drug target. [source] Working memory controls involuntary attention switching: evidence from an auditory distraction paradigmEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2003Stefan Berti Abstract One function of working memory is to protect current mental processes against interference. In contrast, to be able to react flexibly on unpredictable environmental changes working memory should not totally be encapsulated from processing task unrelated information; that is, it should remain distractible. By manipulating the task load of the primary task in an auditory distraction paradigm we investigated how these opposing functions are coordinated by working memory. The behavioural results show that distraction effects were still present but reduced markedly with higher task demands. This suggests that working memory exerts some control over involuntary attention. In addition, event-related brain potentials related to the different processing stages reveal that the preattentive change detection system underlying distraction was not modulated by task demand whereas distraction per se was. The present data suggest that working memory is able to coordinate the maintenance of distractibility and the focus on the task at hand. [source] The neural control of bimanual movements in the elderly: Brain regions exhibiting age-related increases in activity, frequency-induced neural modulation, and task-specific compensatory recruitmentHUMAN BRAIN MAPPING, Issue 8 2010Daniel J. Goble Abstract Coordinated hand use is an essential component of many activities of daily living. Although previous studies have demonstrated age-related behavioral deficits in bimanual tasks, studies that assessed the neural basis underlying such declines in function do not exist. In this fMRI study, 16 old and 16 young healthy adults performed bimanual movements varying in coordination complexity (i.e., in-phase, antiphase) and movement frequency (i.e., 45, 60, 75, 90% of critical antiphase speed) demands. Difficulty was normalized on an individual subject basis leading to group performances (measured by phase accuracy/stability) that were matched for young and old subjects. Despite lower overall movement frequency, the old group "overactivated" brain areas compared with the young adults. These regions included the supplementary motor area, higher order feedback processing areas, and regions typically ascribed to cognitive functions (e.g., inferior parietal cortex/dorsolateral prefrontal cortex). Further, age-related increases in activity in the supplementary motor area and left secondary somatosensory cortex showed positive correlations with coordinative ability in the more complex antiphase task, suggesting a compensation mechanism. Lastly, for both old and young subjects, similar modulation of neural activity was seen with increased movement frequency. Overall, these findings demonstrate for the first time that bimanual movements require greater neural resources for old adults in order to match the level of performance seen in younger subjects. Nevertheless, this increase in neural activity does not preclude frequency-induced neural modulations as a function of increased task demand in the elderly. Hum Brain Mapp, 2010. © 2010 Wiley-Liss, Inc. [source] Person,project fit and R&D performance: a case study of Industrial Technology Research Institute of TaiwanR & D MANAGEMENT, Issue 3 2007Sen-Hao Cheng This study examined the relation between the research and development (R&D) performance and the fit between a researcher's cognitive type and the task demand of the project that was implied in Wang, Wu & Horng's (1999) study. Three hundred and eighteen research projects completed by 205 project leaders in the 3 years were classified into Unsworth's four creativity types along two dimensions: (1) whether the research addressed an open- or closed-ended problem and (2) whether the project was assigned or actively sought by the researcher. Each researcher's personal traits were assessed using Myers,Briggs Type Indicator (MBTI) and Kirton's Adaptor,Innovator Scale (KAI). Results show that researchers with a conforming, feeling, or judging-type cognition performed better with assigned projects for solving closed problems. Those with an originality and intuitive-type cognition performed better on self-initiated projects for solving open-ended problems. Researchers with sensing-type cognition performed better with assigned projects for solving open-ended questions. Thus, a careful match between a researcher's cognitive type and the task demand of project is important for R&D management. [source] The effect of divided attention on inhibiting the gravity errorDEVELOPMENTAL SCIENCE, Issue 3 2006Bruce M. Hood Children who could overcome the gravity error on Hood's (1995) tubes task were tested in a condition where they had to monitor two falling balls. This condition significantly impaired search performance with the majority of mistakes being gravity errors. In a second experiment, the effect of monitoring two balls was compared in the tubes task and a spatial transposition task not involving gravity. Again, monitoring two objects produced impaired search performance in the gravity task but not in the spatial transposition task. These findings support the view that divided attention disrupts the ability to exercise inhibitory control over the gravity error and that the performance drop on this task is not due to the additional task demands incurred by divided attention. [source] Judgment and action knowledge in speed adjustment tasks: experiments in a virtual environmentDEVELOPMENTAL SCIENCE, Issue 2 2003Susanne Huber Two experiments were conducted to investigate children's and adults' knowledge of time and speed in action and judgment tasks. Participants had to set the speed of a moving car to a new speed so that it would reach a target line at the same time as a reference car moving at a higher speed and disappearing in a tunnel at the midway point. In Experiment 1 (24 10-year-olds, 24 adults), children's and adults' speed adjustments followed the normative pattern when responses had to be graded linearly as a function of the car's initial speed. In a non-linear condition, only adults' action responses corresponded with the normative function. Simplifying the task by shortening the tunnel systematically in Experiment 2 (24 10-year-olds, 24 adults) enabled children to grade the speeds adequately in the action conditions only. Adults now produced normative response patterns in both judgment and action. Whether people show linearization biases was thus shown to depend on the interaction of age, task demands and response mode. [source] The validity of self-reports of alcohol consumption: state of the science and challenges for researchADDICTION, Issue 2003Frances K. Del Boca ABSTRACT Aims To review three topics pertaining to the validity of alcohol self-reports: factors that influence response accuracy; the relative merits of different self-report approaches; and the utility of using alternative measures to confirm verbal reports. Findings Response behavior is influenced by the interaction of social context factors, respondent characteristics, and task attributes. Although research has advanced our knowledge about self-report methods, many questions remain unanswered. In particular, there is a need to investigate how task demands interact with different patterns of drinking behavior to affect response accuracy. There is also a continuing need to use multiple data sources to examine the extent of self-report response bias, and to determine whether it varies as a function of respondent characteristics or assessment timing. Conclusion Self-report methods offer a reliable and valid approach to measuring alcohol consumption. The accuracy of such methods, however, can be improved by research directed at understanding the processes involved in response behavior. [source] Basal ganglia and frontal involvement in self-generated and externally-triggered finger movements in the dominant and non-dominant handEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2009Félix-Etienne François-Brosseau Abstract Although there are a number of functional neuroimaging studies that have investigated self-initiated and externally-triggered movements, data directly comparing right and left hands in this context are very scarce. The goal of this study was to further understand the role of the basal ganglia and prefrontal cortex in the realm of self-initiated and externally-triggered right and left hand movements. Young healthy right-handed adults performed random, follow and repeat conditions of a finger moving task with their right and left hands, while being scanned with functional magnetic resonance imaging. Significant activation of the dorsolateral prefrontal cortex was observed when comparing the self-initiated movements with the repeated control and externally-triggered movements when using either hand in agreement with its role in monitoring. The caudate nucleus activation was found during self-initiated conditions compared with the control condition when either hand was used, showing that it is particularly involved when a new movement needs to be planned. Significant putamen activation was observed in all within-hand contrasts except for the externally-triggered vs. control condition when using the left hand. Furthermore, greater putaminal activation was found for the left vs. the right hand during the control condition, but for the right vs. the left hand subtraction for the self-initiated condition. Our results show that the putamen is particularly involved in the execution of non-routine movements, especially if those are self-initiated. Furthermore, we propose that, for right-handed people performing fine movements, as far as putamen involvement is concerned, the lack of proficiency of the non-dominant hand may prevail over other task demands. [source] Spatial and temporal analysis of fMRI data on word and sentence readingEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2007Sven Haller Abstract Written language comprehension at the word and the sentence level was analysed by the combination of spatial and temporal analysis of functional magnetic resonance imaging (fMRI). Spatial analysis was performed via general linear modelling (GLM). Concerning the temporal analysis, local differences in neurovascular coupling may confound a direct comparison of blood oxygenation level-dependent (BOLD) response estimates between regions. To avoid this problem, we parametrically varied linguistic task demands and compared only task-induced within-region BOLD response differences across areas. We reasoned that, in a hierarchical processing system, increasing task demands at lower processing levels induce delayed onset of higher-level processes in corresponding areas. The flow of activation is thus reflected in the size of task-induced delay increases. We estimated BOLD response delay and duration for each voxel and each participant by fitting a model function to the event-related average BOLD response. The GLM showed increasing activations with increasing linguistic demands dominantly in the left inferior frontal gyrus (IFG) and the left superior temporal gyrus (STG). The combination of spatial and temporal analysis allowed a functional differentiation of IFG subregions involved in written language comprehension. Ventral IFG region (BA 47) and STG subserve earlier processing stages than two dorsal IFG regions (BA 44 and 45). This is in accordance with the assumed early lexical semantic and late syntactic processing of these regions and illustrates the complementary information provided by spatial and temporal fMRI data analysis of the same data set. [source] Repetition suppression of induced gamma band responses is eliminated by task switchingEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2006Thomas Gruber Abstract The formation of cortical object representations requires the activation of cell assemblies, correlated by induced oscillatory bursts of activity >,20 Hz (induced gamma band responses; iGBRs). One marker of the functional dynamics within such cell assemblies is the suppression of iGBRs elicited by repeated stimuli. This effect is commonly interpreted as a signature of ,sharpening' processes within cell-assemblies, which are behaviourally mirrored in repetition priming effects. The present study investigates whether the sharpening of primed objects is an automatic consequence of repeated stimulus processing, or whether it depends on task demands. Participants performed either a ,living/non-living' or a ,bigger/smaller than a shoebox' classification on repeated pictures of everyday objects. We contrasted repetition-related iGBR effects after the same task was used for initial and repeated presentations (no-switch condition) with repetitions after a task-switch occurred (switch condition). Furthermore, we complemented iGBR analysis by examining other brain responses known to be modulated by repetition-related memory processes (evoked gamma oscillations and event-related potentials; ERPs). The results obtained for the ,no-switch' condition replicated previous findings of repetition suppression of iGBRs at 200,300 ms after stimulus onset. Source modelling showed that this effect was distributed over widespread cortical areas. By contrast, after a task-switch no iGBR suppression was found. We concluded that iGBRs reflect the sharpening of a cell assembly only within the same task. After a task switch the complete object representation is reactivated. The ERP (220,380 ms) revealed suppression effects independent of task demands in bilateral posterior areas and might indicate correlates of repetition priming in perceptual structures. [source] Prefrontal-subcortical dissociations underlying inhibitory control revealed by event-related fMRIEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2004A. M. Clare Kelly Abstract 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. [source] Working memory controls involuntary attention switching: evidence from an auditory distraction paradigmEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2003Stefan Berti Abstract One function of working memory is to protect current mental processes against interference. In contrast, to be able to react flexibly on unpredictable environmental changes working memory should not totally be encapsulated from processing task unrelated information; that is, it should remain distractible. By manipulating the task load of the primary task in an auditory distraction paradigm we investigated how these opposing functions are coordinated by working memory. The behavioural results show that distraction effects were still present but reduced markedly with higher task demands. This suggests that working memory exerts some control over involuntary attention. In addition, event-related brain potentials related to the different processing stages reveal that the preattentive change detection system underlying distraction was not modulated by task demand whereas distraction per se was. The present data suggest that working memory is able to coordinate the maintenance of distractibility and the focus on the task at hand. [source] Locus of control and the flow experience: An experimental analysisEUROPEAN JOURNAL OF PERSONALITY, Issue 7 2008Johannes Keller Abstract The present research addresses the notion that the compatibility of skills and task demands involved in a given activity elicits a flow experience that renders the respective activity rewarding. The study employed an experimental paradigm to document the causal impact of skills,demands compatibility on the emergence of flow and revealed that participants characterized by a strong internal locus of control (LOC) were most sensitive to the manipulation of skills,demands compatibility and experienced flow under conditions of a fit of skills and task demands, whereas individuals with a weak internal LOC did not enter the state of flow. In line with previous findings, this suggests that distinct personality attributes are of critical relevance for the experience of flow to emerge. Copyright © 2008 John Wiley & Sons, Ltd. [source] Language dominance assessment by means of fMRI: Contributions from task design, performance, and stimulus modalityJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2001Margret Hund-Georgiadis MD Abstract We investigated the influence of different task demands, task designs, and presentation modalities on the functional MRI activation patterns during a language lateralization task in a group of 14 right-handed control subjects. A word classification task was presented as target task appropriate to evoke language-related activation in the inferior frontal gyrus (IFG). The choice of the contrasting baseline task was demonstrated to have a major impact on the functional outcome: While a fixation baseline elicited activations in the inferior frontal gyrus of both hemispheres, a nonsemantic perceptual control task helped to isolate the relevant target task of word classification. The modality of stimulus presentation did not influence the functional data: Auditory and visual presentation modes broadly evoked activations in similar brain regions during word classification. Minor differences in task performance and the side of the responding hand did not interfere with the functional activation patterns of the target task. On the basis of our results, a protocol of functional lateralization in the inferior frontal gyrus is suggested. J. Magn. Reson. Imaging 2001;13:668,675. © 2001 Wiley-Liss, Inc. [source] Modulation of the human mirror neuron system during cognitive activityPSYCHOPHYSIOLOGY, Issue 6 2008Suresh D. Muthukumaraswamy Abstract In this experiment we examined the relationship between the mirror neuron system and increased attention caused by task demands. Whole head MEG recordings were made from 13 participants who were asked to passively observe finger movement sequences, observe these sequences with the knowledge they would later have to perform the sequence presented, and finally, to perform a nonmotor mathematics task based on the finger-movement sequences. Beta-band (15,35 Hz) sensorimotor desynchronization was found in overlapping areas during passive observation and in a separate motor execution condition, indicating the activity of the human mirror neuron system. The beta desynchronization in these areas was enhanced relative to passive viewing when participants had to watch the stimuli to later imitate and when they performed the mathematics task, indicating that mirror neuron system activity can be modulated by attention. [source] Expertise and self-regulation processes in a professional taskAPPLIED COGNITIVE PSYCHOLOGY, Issue 7 2009Nathalie Huet This study investigated self-regulation processes in a professional task, a beverage service task, using the model of self-regulated study. The main purpose was to explore how self-regulatory activity changes both with professional experience and with memory task demands. In a simulated beverage service task, 22 beginner waiters and 22 experienced waiters were asked to request the drink ordered by each customer until they were sure they knew the entire order. Then, they had to execute an immediate recall of the customer-beverage pairs and a delayed recall. Results showed that globally beginners did not modify their self-regulation processes as a function of task demands. By contrast to beginners, experienced waiters increased their self-regulatory activity when they had to face with a more demanding task. Besides, experts showed higher recall performance than beginners under all conditions. In the conclusion, results from this more naturalistic task were compared to those obtained in experimental studies and discussed. Copyright © 2008 John Wiley & Sons, Ltd. [source] Interruptions create prospective memory tasksAPPLIED COGNITIVE PSYCHOLOGY, Issue 1 2009Rahul M. Dodhia When the theory of prospective memory is brought to bear on the ubiquitous experience of failing to resume interrupted tasks, the cognitive reasons for these failures may be understood and addressed. We examine three features of interruptions that may account for these failures: (1) Interruptions often abruptly divert attention, which may prevent adequate encoding of an intention to resume and forming an implementation plan, (2) New task demands after an interruption's end reduce opportunity to interpret resumption cues, (3) The transition after an interruption to new ongoing task demands is not distinctive because it is defined conceptually, rather than by a single perceptual cue. Hypotheses based on these three features receive support from two experiments that respectively manipulate encoding and retrieval conditions. The data support our contention that interrupted tasks are a special case of prospective memory, and allow us to suggest practical ways of reducing vulnerability to resumption failure. Copyright © 2008 John Wiley & Sons, Ltd. [source] Breaks and task switches in prospective memoryAPPLIED COGNITIVE PSYCHOLOGY, Issue 5 2006Kraig Finstad Based on research showing that easing task demands improves prospective memory, we examined the effects of breaks and task switches on prospective memory. The first experiment suggested that people tend not to take advantage of breaks to improve prospective memory unless specifically instructed to do so. The next two experiments showed that both breaks and task switches interfered with prospective memory. The results indicate that work settings with frequent breaks and task switches may be especially susceptible to prospective memory failure. Copyright © 2006 John Wiley & Sons, Ltd. [source] Neural correlates of deficient response inhibition in mentally disordered violent individualsBEHAVIORAL SCIENCES & THE LAW, Issue 1 2008Ian Barkataki Ph.D. In this study, response inhibition and associated neural activation during a motor inhibition paradigm were investigated in (i) men with antisocial personality disorder (APD) with a history of violence (n,=,14), (ii) men with schizophrenia with a history of violence (n,=,12), (iii) men with schizophrenia without a history of violence (n,=,12), and (iv) healthy control subjects (n,=,14) using functional magnetic resonance imaging (fMRI). At the behavioural level, individuals with schizophrenia showed impaired performance across all conditions, whereas an increased error rate was seen in the APD group only during the conditions requiring inhibition. At the neural level, both violent groups showed reduced thalamic activity, compared with controls, in association with modulation of inhibition by task demands. In addition, the violent schizophrenia group, compared with controls, showed reduced activity in the caudate nucleus during the condition requiring inhibition. It is concluded that violence may not be specifically associated with impaired voluntary inhibition in schizophrenia but this is likely in APD. Reduced thalamic function, perhaps due to its known association with sensorimotor disturbances, is implicated in violent behaviour across both disorders. In addition, caudate dysfunction may contribute, given its role in timing and temporal processing as well as suppression of motor actions, to deficient inhibition and violent behaviour in schizophrenia. Copyright © 2008 John Wiley & Sons, Ltd. [source] The evolution of intelligence: adaptive specializations versus general processBIOLOGICAL REVIEWS, Issue 3 2001EUAN M. MAGPHAIL ABSTRACT Darwin argued that between-species differences in intelligence were differences of degree, not of kind. The contemporary ecological approach to animal cognition argues that animals have evolved species-specific and problem-specific processes to solve problems associated with their particular ecological niches: thus different species use different processes, and within a species, different processes are used to tackle problems involving different inputs. This approach contrasts both with Darwin's view and with the general process view, according to which the same central processes of learning and memory are used across an extensive range of problems involving very different inputs. We review evidence relevant to the claim that the learning and memory performance of non-human animals varies according to the nature of the stimuli involved. We first discuss the resource distribution hypothesis, olfactory learning-set formation, and the ,biological constraints' literature, but find no convincing support from these topics for the ecological account of cognition. We then discuss the claim that the performance of birds in spatial tasks of learning and memory is superior in species that depend heavily upon stored food compared to species that either show less dependence upon stored food or do not store food. If it could be shown that storing species enjoy a superiority specifically in spatial (and not non-spatial) tasks, this would argue that spatial tasks are indeed solved using different processes from those used in non-spatial tasks. Our review of this literature does not find a consistent superiority of storing over non-storing birds in spatial tasks, and, in particular, no evidence of enhanced superiority of storing species when the task demands are increased, by, for example, increasing the number of items to be recalled or the duration of the retention period. We discuss also the observation that the hippocampus of storing birds is larger than that of non-storing birds, and find evidence contrary to the view that hippocampal enlargement is associated with enhanced spatial memory; we are, however, unable to suggest a convincing alternative explanation for hippocampal enlargement. The failure to find solid support for the ecological view supports the view that there are no qualitative differences in cognition between animal species in the processes of learning and memory. We also argue that our review supports our contention that speculation about the phylogenetic development and function of behavioural processes does not provide a solid basis for gaining insight into the nature of those processes. We end by confessing to a belief in one major qualitative difference in cognition in animals: we believe that humans alone are capable of acquiring language, and that it is this capacity that divides our intelligence so sharply from non-human intelligence. [source] Development of Mental Attention in Gifted and Mainstream Children: The Role of Mental Capacity, Inhibition, and Speed of ProcessingCHILD DEVELOPMENT, Issue 6 2003Janice Johnson The study examined performance of 6- to 11-year-old children, from gifted and mainstream academic programs, on measures of mental-attentional capacity, cognitive inhibition, and speed of processing. In comparison with mainstream peers, gifted children scored higher on measures of mental-attentional capacity, responded more quickly on speeded tasks of varying complexity, and were better able to resist interference in tasks requiring effortful inhibition. There was no group difference on a task requiring automatic inhibition. Comparisons between older and younger children yielded similar results. Correlations between inhibition tasks suggest that inhibition is multidimensional in nature, and its application may be affected by task demands. Measures of efficiency of inhibition and speed of processing did not explain age or group differences on a complex intellective measure of mental-attentional capacity. [source] | ||||||||||||||||