Mental Task Performance Research Articles

Effect of dried-bonito broth on mental fatigue and mental task performance in subjects with a high fatigue score

Dried-bonito broth is commonly employed as a soup and sauce base in Japanese cuisine and is considered to be a nutritional supplement that promotes recovery from fatigue. Previous human trials suggest that the ingestion of dried-bonito broth improves several mood states; however, its effect on fatigue has not yet been clarified. The aim of this study was to clarify the effects of daily ingestion of dried-bonito broth on fatigue and cognitive parameters by a placebo-controlled double blind crossover trial. Forty-eight subjects with fatigue symptoms ingested the dried-bonito broth or a placebo solution every day for 4 weeks. Mood states were evaluated by the Profile of Mood States (POMS), and mental task performance was evaluated by the Uchida–Kraepelin psychodiagnostic (UKP) test. Fatigue and total mood disturbance (TMD) scores on the POMS test decreased significantly during the dried-bonito broth ingestion ( p < 0.05), but did not change significantly during placebo ingestion. The change in vigor score during dried-bonito broth ingestion was significantly higher than that during placebo ingestion at 2 weeks ( p < 0.05). The results of the UKP test indicate that the numbers of both total answers and correct answers significantly increased during dried-bonito broth ingestion ( p < 0.05), while no significant changes were observed in the placebo ingestion. These results suggest that the daily ingestion of dried-bonito broth may improve the mood states, may reduce mental fatigue and may increase performance on a simple calculation task.

The Effects of Sex, Sexual Orientation, and Digit Ratio (2D:4D) on Mental Rotation Performance

In spite of the reduced level of experimental control, this large scale study brought some clarity into the relation between mental rotation task (MRT) performance and a number of variables where contradictory associations had previously been reported in the literature. Clear sex differences in MRT were observed for a sample of 134,317 men and 120,783 women, with men outperforming women. There were also MRT differences as a function of sexual orientation: heterosexual men performed better than homosexual men and homosexual women performed better than heterosexual women. Although bisexual men performed better than homosexual men but less well than heterosexual men, no significant differences were observed between bisexual and homosexual women. MRT performance in both men and women peaked in the 20-30 year range, and declined significantly and markedly thereafter. Both men and women showed a significant negative correlation between left and right digit finger ratio and MRT scores, such that individuals with smaller digit ratios (relatively longer ring finger than index finger) performed better than individuals with larger digit ratios.

Quantitative EEG and Electromagnetic Brain Imaging in Aging and in the Evolution of Dementia

Electroencephalographic (EEG) changes with normal aging have long been reported. Departures from age-expected changes have been observed in mild cognitive impairment and dementia, the magnitude of which correlates with the degree of cognitive impairment. Such abnormalities include increased delta and theta activity, decreased mean frequency, and changes in coherence. Similar findings have been reported using magnetoencephalography (MEG) at rest and during performance of mental tasks. Electrophysiological features have also been shown to be predictive of future decline in mild cognitive impairment (MCI) and Alzheimer's disease (AD). We have recently reported results from initial quantitative electroencephalography (QEEG) evaluations of normal elderly subjects (with only subjective reports of memory loss), predicting future cognitive decline or conversion to dementia, with high prediction accuracy (approximately 95%). In this report, source localization algorithms were used to identify the mathematically most probable underlying generators of abnormal features of the scalp-recorded EEG from these patients with differential outcomes. Using this QEEG method, abnormalities in brain regions identified in studies of AD using MEG, MRI, and positron emission tomography (PET) imaging were found in the premorbid recordings of those subjects who go on to decline or convert to dementia.

Exposure to Bright Light Modifies HRV Responses to Mental Tasks during Nocturnal Sleep Deprivation

This study was intended to determine the effects of continuous bright light exposure on cardiovascular responses, particularly heart rate variability (HRV), at rest and during performance of mental tasks with acute nocturnal sleep deprivation. Eight healthy male subjects stayed awake from 21.00 to 04.30 hours under bright (BL, 2800 lux) or dim (DL, 120 lux) light conditions. During sleep deprivation, mental tasks (Stroop color-word conflict test: CWT) were performed for 15 min each hour. Blood pressure, electrocardiogram, respiratory rate, urinary melatonin concentrations and rectal temperature were measured. During sleep deprivation, BL exposure depressed melatonin secretion in comparison to DL conditions. During sleep deprivation, exposure to BL delayed the decline in heart rate (HR) for 4 h in resting periods. A significant increment of HR induced by each CWT was detected, especially at 03.00 h and later, under DL conditions only. In addition, at 04.00 h, an index of sympathetic activity and sympatho-vagal balance on HRV during CWT increased significantly under DL conditions. In contrast, an index of parasympathetic activity during CWT decreased significantly under DL conditions. However, the indexes of HRV during CWT did not change throughout sleep deprivation under BL conditions. Our results suggest that BL exposure not only delays the nocturnal decrease in HR at rest but also maintains HR and balance of cardiac autonomic modulation to mental tasks during nocturnal sleep deprivation.

Control over the scheduling of simulated office work reduces the impact of workload on mental fatigue and task performance.

Two experiments tested the hypothesis that task-induced mental fatigue is moderated by control over work scheduling. Participants worked for 2 hr on simulated office work, with control manipulated by a yoking procedure. Matched participants were assigned to conditions of either high control (HC) or low control (LC). HC participants decided their own task scheduling, whereas LC participants had to follow these fixed schedules. For Experiment 1, fatigue was higher in LC participants who worked harder, so Experiment 2 compared control effects in high- and low-workload groups. As predicted, the impact of workload was reduced under HC conditions, for subjective fatigue, and most secondary tasks and aftereffects. The findings are interpreted within the framework of compensatory control theory.

Stimulation of Cortisol During Mental Task Performance in a Provocative Virtual Environment

Fully immersive and stereoscopic Virtual Environments (VE) represent a powerful multimedia tool for laboratory-based simulations of distinct scenarios including scenarios for evaluating stressful situations resembling reality. Thus far, cortisol secretion as a neuroendocrine parameter of stress has not been evaluated within a Virtual Reality (VR)-based paradigm. In this study 94 healthy volunteers were subjected to a provocative VR-paradigm and a cognitive stress task. Provocative in this context means the VE was designed to provoke physiological reactions (cortisol secretion) within the respective users by purpose. It was tested (a) if a fully dynamic VE as opposed to a static VE can be regarded as a stressor and (b) if such a fully dynamic VE can modify an additional response to a cognitive stressor presented within the VE additionally. Furthermore, possible gender-related impacts on cortisol responses were assessed. A significant cortisol increase was observed only after the combined application of the fully dynamic VE and the cognitive stressor, but not after application of the dynamic VE or the cognitive stressor alone. Cortisol reactivity was greater for men than for women. We conclude that a fully dynamic VE does not affect cortisol secretion per se, but increases cortisol responses to a dual task paradigm that includes performance of a stressful mental task. This provides the basis for the application of VR-based technologies in neuroscientific research, including the assessment of the human Hypothalamus-Pituitary-Adrenal (HPA) axis regulation.

Nonlinear Analysis of Cortical Activity during Mental Task Performance

Nonlinear Analysis of Cortical Activity during Mental Task Performance

Introducing a baroreflex model for studying cardiovascular effects of mental workload

A quantitative baroreflex control model is presented aimed at estimating differences in autonomic activation due to mental task performance. The model, which builds on earlier work of Wesseling and colleagues, is strongly supported by well-established knowledge of physiological control processes. Spectral measures of heart rate and blood pressure variability provide the information to estimate autonomic gain and tone parameters. The article gives a detailed model description as well as an evaluation in terms of spectral variability distributions, respiratory sinus arrhythmia, and vagal control mechanisms. The estimation procedure is outlined while presenting two studies that describe the effects of mental workload and vagal blockade, respectively. It is concluded that, using the model approach, cardiovascular effects of mental task performance can be interpreted in terms of specific changes in autonomic state. The model is implemented in a Matlab/Simulink environment and is available for other researchers in the field.

Antiaging treatments have been legally prescribed for approximately thirty years.

There is an interesting divergence between the achievements of geriatrics and gerontology. On the one hand, during the last 30 years physicians in many developed countries have successfully prescribed several medicines to cure various symptoms of senescence. On the other hand, the influence of such medicines on human life span practically has not been studied. The most common of the relevant medicines are nootropic piracetam, gamma-aminobutyric acid (GABA), selegiline, Ginkgo biloba, pentoxifylline, cerebrolysin, solcoseryl, ergoloid, vinpocetin, sertraline, and estrogens, among others. Available data from human clinical practices and experimental animal studies indicate that treatments with these drugs improve learning, memory, brain metabolism, and capacity. Some of these drugs increase tolerance to various stresses such as oxygen deficit and exercise, stimulate the regeneration of neurons in the old brain, and speed up the performance of mental and physical tasks. This means that modern medicine already has "antiaging" treatments at its disposal. However, the influence of such treatments on the mean and maximal life span of humans, and on the age trajectory of a human survival curve has been poorly studied. The increase in human life expectancy at birth in the second half of the last century was mostly caused by the better survival at the old and oldest old rather than at the young ages. In parallel, the consumption of brain protective and regenerative drugs has been expanding in the elderly population. We provide evidence in support of the idea that the consumption of medicines exerting antiaging properties may contribute to the increase in human longevity.

Hostility disturbs learning.

Many studies have shown that there is a strong correlation between hostility and coronary artery disease; however, the pathogenic mechanisms by which hostility causes coronary artery disease have not been identified. Several studies have shown that hostility is associated with increased cardiovascular reactivity to mental stress. Sloan and colleagues used mental arithmetic and the Stroop Color-Word Task as psychological stressors and suggested that hostility is associated with diminished cardiac vagal control. It is supposed that the diminished cardiac vagal control results in uncontrollability of increased heart rate under stressful conditions so performance on mental stress tasks is poor. However, performance was not analyzed on the Stroop Color-Word Task. If hostility influences the autonomic nervous system, the performance of this mental stress task may also differ according to extent of hostility. In the present study, whether hostility disturbed performance of a mental stress task and the practice on it was examined. Subjects completed the Cook-Medley Hostility Scale and were divided into three groups (High, Middle, and Low) by their total scores and three subscales (Cynicism, Hostile Affect, and Aggressive Responding). They also completed the Stroop Color-Word Task. Analysis showed practice by High and Middle scoring groups on Aggressive Responding had a significantly smaller effect than that by Low scoring groups. The pathogenic mechanisms by which hostility may underlie coronary artery disease were discussed.

Posture and mental task performance when viewing a moving visual field

We investigated the characteristics of standing posture and performance of concurrent cognitive tasks in subjects confronted by whole field visual motion. Movements of the head and centre of pressure (COP) were recorded in 12 subjects who performed modified Brooks spatial and verbal tasks when in quiet stance viewing a chequerboard pattern, planar, visual field, moving with uniform velocity (25°/s, 50°/s and 76°/s). Eight subjects were also tested seated to control for the effect of stance. Task load was monitored by heart rate and eye movements were recorded to ensure viewing compliance. Subjects rated their quotidian susceptibility to visual disorientation on a validated scale. In both lateral and antero-posterior directions there were small amplitude but significant increases in COP sway path length and standard deviations of both COP and head sway during exposure to visual motion in proportion to visual flow speed. Performing cognitive tasks during visual motion attenuated sway S.D. The effects on sway of task and visual flow were independent. Visual motion induced a slight tilt and turn of the head and body in the direction of flow together with slight neck flexion. Errors on both verbal and spatial tasks increased >250% during visual motion both when standing and when seated. Ratings of subjects’ susceptibility to disorientation were un-related to either verbal or spatial task error rates. A current hypothesis is that the enhancement of sway by visual motion is destabilisation. We propose an alternative explanation that sway enhancement could be exploratory ‘testing of the ground’ movements to check for self motion. Hence decrease in sway magnitude during a cognitive task could be caused by a reduction in exploratory movement because attention is diverted from postural control to a secondary task. Mere passive viewing of a moving visual field may interfere with cognitive tasks possibly because the threat of disorientation by whole field motion diverts attentional resources.

A picture is worth a thousand connections: the facilitative effects of diagrams on mental model development and task performance

This study investigated the influence of training format on knowledge structure development and how differing knowledge structure measurement techniques can be used to best assess training effectiveness. The presence of diagrams was manipulated in a computer-based training tutorial designed to assess mental model development and knowledge acquisition. Participants presented with diagrams were more likely to accurately draw connections across modules of the training. Diagrams also facilitated performance on measures of integrative knowledge but not on measures of declarative knowledge. The results are discussed in the context of mental model theory.

The Influence of Emotionally Relevant Context on the Evoked Cardiac Response Triggered by an Irrelevant Stimulus

Abstract The effect of stimulus valence was examined in the evoked cardiac response (ECR) elicited by the exposition of neutral and negative slides as well as by an innocuous auditory stimulus presented on the affective foregrounds generated by the slides. The exposition of the aversive slide produced prolonged cardiac deceleration in comparison with the neutral slide. Similar prolonged deceleration accompanied exposition of the neutral auditory stimulus on the negative visual foreground in comparison with the neutral foreground. We interpret these results as an autonomic correlate of extended stimulus processing associated with the affective stimulus. The initial deceleration response, covering two or three slower heart beats, may be prolonged for several seconds before HR reaches the baseline level again. In such a case the evoked cardiac deceleration can be functionally divided into two parts: the reflexive bradycardia (ECR1) elicited by neutral stimuli and a late decelerative component (LDC). We can speculate that the latter is associated with an additional voluntary continuation of processing of the stimulus. This must involve some cognitive aspect different from the mental task performance which leads to the accelerative ECR2, and we suggest that processing of a stimulus with negative valence is involved in generating the LDC.

Summary, conclusions and recommendations: adverse temperature levels in the human body

In the spring of 2002, The World Health Organization workshop 'Adverse Temperature Levels in the Human Body' brought together scientists with expertise in biological effects of hyperthermia to review the data and determine the evidence that could be used to evaluate potential adverse effects from human exposures to radiofrequency (RF) electromagnetic radiation in the range of 10-300 GHz. Standards for RF exposure in this frequency range are based currently on thermal effects. Information was reviewed on the ability of hyperthermia, either to the whole body or to part of the body to affect physiology, particularly the heart and circulatory system, to induce other thermoregulatory responses such as sweating, to affect the performance of simple and complex mental tasks, to induce various heat-related disorders such as heat stroke and to damage body tissue. Risks to a variety of organs were considered. In addition, thresholds for effects on developing embryos and foetuses and possible carcinogenic effects were also examined. These findings were discussed in the context of known cellular and biochemical responses of cells and tissues to hyperthermia. The experts judged the relevance of each study for informing decision-makers on the scientific basis for establishing safe exposure levels. The consensus was that standards should consider both temperature and time of exposure, whenever possible.

Spatial task performance, sex differences, and motion sickness susceptibility.

There are substantial individual differences in susceptibility to motion sickness, yet little is known about what mediates these differences. Spatial ability and sex have been suggested as possible factors in this relationship. 89 participants (57 women) were administered a Motion Sickness Questionnaire that assesses motion sickness susceptibility, a Water-level Task that gauges sensitivity to gravitational upright, and a Mental Rotation Task that tests an individual's awareness of how objects typically move in space. Significant sex differences were observed in performance of both the Water-level Task (p<.01), and the Mental Rotation Task (p<.005), with women performing less accurately than men. Women also had significantly higher scores on the Motion Sickness Questionnaire (p<.005). Among men, but not women, significant negative relationships were observed between Water-level Task performance and Motion Sickness Questionnaire score (p<.001) and between Mental Rotation Task performance and Motion Sickness Questionnaire score (p<.005). In conclusion, women performed significantly more poorly than men did on the spatial ability tasks and reported significantly more bouts of motion sickness. In addition, men showed a significant negative relationship between spatial ability and motion sickness susceptibility.

The Relationship of Group Process Variables and Team Performance

The efficacy of three group process variables—group potency, social cohesion, and team-member exchange—in explaining team performance was examined for 648 military officers working in 50 self-managed teams over a 5-week period. Team performance was assessed on two objective criteria (mental task performance and physical task performance) and one subjective criterion (commander team performance ratings). Each of the group process variables was related to at least one aspect of team performance. Of the three group process variables, group potency exhibited the greatest predictive efficacy as it explained unique variance in team performance over that accounted for by both social cohesion and team-member exchange.

SPATIAL TASK PERFORMANCE, SEX DIFFERENCES, AND MOTION SICKNESS SUSCEPTIBILITY

There are substantial individual differences in susceptibility to motion sickness, yet little is known about what mediates these differences. Spatial ability and sex have been suggested as possible factors in this relationship. 89 participants (57 women) were administered a Motion Sickness Questionnaire that assesses motion sickness susceptibility, a Water-level Task that gauges sensitivity to gravitational upright, and a mental Rotation Task that tests an individual's awareness of how objects typically move in space. Significant sex differences were observed in performance of both the Water-level Task (p<.01), and the Mental Rotation Task (p<.005), with women performing less accurately than men. Women also had significantly higher scores on the Motion Sickness Questionnaire (p<.005) Among men, but not women, significant negative relationships were observed between Water-level Task performance and Motion Sickness Questionnaire score (p<.001) and between Mental Rotation Task performance and Motion Sickness Questionnaire score (p<.005). In conclusion, women performed significantly more poorly than men did on the spatial ability tasks and reported significantly more bouts of motion sickness. In audition, men showed a significant negative relationship between spatial ability and motion sickness susceptibility.

In Summary: Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations.

Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations is available for sale from the National Academy Press, 2101 Constitution Avenue, NW, Box 285, Washington, DC 20055; call (800) 624-6242 or (202) 334-3313 (in the Washington metropolitan area), or visit the NAP’s on-line bookstore at http://www.nap.edu. For more information about the Institute of Medicine, visit the IOM home page at http://www.iom.edu. Support for this project was provided by the US Department of the Army, Army Medical Research and Materiel Command through grant No. DAMD17-94-J-4046 and grant No. DAMD17-99-1-9478. The US Army Medical Reearch Acquisition Activity, 820 Chandler Street, Fort Detrick, MD 21702-5014, is the awarding and administering acquisition office. The views presented in this publication are those of the Committee on Military Nutrition Research and do not necessarily reflect the position or policy of the government, and no official endorsement should be inferred. © 2001 by the National Academy of Sciences Permission is granted to reproduce this report brief in its entirety, with no additions or alterations.

Modeling Mental Workload and Task Performance for Indirect Vision Driving

Cognitive workload and task performance are modeled for indirect vision driving with fixed flat panel displays. The model is derived from the results of a field study in which eight participants negotiated a driving course in a military vehicle with natural and indirect vision. For the latter, the vehicle was driven with fixed flat panel, liquid crystal displays in the cab and a forward viewing monocular camera array mounted on the front roof of the vehicle and tilted slightly downward. In addition to recording driving performance, the study collected test battery ratings of the mental workload measures of attention allocation, perceived workload, situational awareness, motion sickness, perceived stress, and cognitive performance. As a result of the study, a mathematical model of road speed was derived for indirect vision driving as a function of the camera's field of view. The model considers the effects of scene compression on the informational needs of the driver in a self-paced task. Concurrently, a task analysis mental workload model was derived for indirect vision driving by mapping the cognitive and mental workload measures to a “skills-rules-knowledge” model of information processing. The model successfully explains apparently conflicting results for indirect vision driving from different experiments that examined on-board and teleoperations from the different camera lens used in the studies.

Interference between postural control and mental task performance in patients with vestibular disorder and healthy controls

OBJECTIVESTo determine whether interference between postural control and mental task performance in patients with balance system impairment and healthy subjects is due to general capacity limitations, motor control interference, competition...