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Although the focus of the discussion regarding the significance of the error related negatively (ERN/Ne) has been on the cognitive factors reflected in this component, there is now a growing body of research that describes influences of motivation, affective style and other factors of personality on ERN/Ne amplitude. The present study was conducted to further evaluate the relationship between affective style, error related ERP components and their neural basis. Therefore, we had our subjects fill out the Behavioral Activation System/Behavioral Inhibition System (BIS/BAS) scales, which are based on Gray's (1987, 1989) biopsychological theory of personality. We found that subjects scoring high on the BIS scale displayed larger ERN/Ne amplitudes, while subjects scoring high on the BAS scale displayed larger error positivity (Pe) amplitudes. No correlations were found between BIS and Pe amplitude or between BAS and ERN/Ne amplitude. Results are discussed in terms of individual differences in reward and punishment sensitivity that are reflected in error related ERP components.

We tested whether behavioural manifestations of mental fatigue may be linked to compromised executive control, which refers to the ability to regulate perceptual and motor processes for goal-directed behaviour. In complex tasks, compromised executive control may become manifest as decreased flexibility and sub-optimal planning. In the study we use the Wisconsin Card Sorting Test (WCST) and the Tower of London (TOL), which respectively measure flexibility (e.g., perseverative errors) and planning. A simple memory task was used as a control measure. Fatigue was induced through working for 2 h on cognitively demanding tasks. The results showed that compared to a non-fatigued group, fatigued participants displayed more perseveration on the WCST and showed prolonged planning time on the TOL. Fatigue did not affect performance on the simple memory task. These findings indicate compromised executive control under fatigue, which may explain the typical errors and sub-optimal performance that are often found in fatigued people. (C) 2002 Elsevier Science B.V. All rights reserved.

The present study investigated the acute effects of cortisol administration in normal healthy male volunteers on immediate free recall and recognition of pleasant, unpleasant, and neutral nouns using a between-subjects double-blind design. Two hours after cortisol (10 mg) or placebo administration, impaired recall and recognition of neutral and pleasant words was found in the treatment group, whereas recall and recognition of unpleasant words was similar in both groups. The interaction between treatment and stimulus valence was not mediated by "semantic cohesion," nor does it seem to have been mediated by stimulus arousal. Cortisol did not change mood. The changes with cortisol in recall and recognition of pleasant and unpleasant words parallel those found in depression, a condition that is often accompanied by elevated basal cortisol levels.

The effects of variables derived from a work stress theory (the effort-reward imbalance theory) on the power in the high frequency (HF_HRV) band of heart rate (0.14-0.40 Hz) throughout a work day, were determined using multilevel analysis. Explanatory variables were analysed at two levels: at the lowest level (within-day level), the effects of positive mood, negative mood, demand, satisfaction, demand-satisfaction ratio, and time of day were assessed. At the highest level (the subject level), the effects of sleep quality, effort, reward, effort-reward imbalance, need for control, type of work (profession), negative affectivity, gender and smoking on HF_HRV were assessed. Need for control has a negative effect on HF_HRV after controlling for time of day effects, i.e. subjects with a high need for control have a lower vagal control of the heart. In the long run, these subjects may be considered to be at increased health risk, because they have less of the health protective effects of vagal tone. The interaction between effort-reward imbalance and time of day has a positive effect on HF_HRV, i.e, the cardiac vagal control of subjects with a high effort-reward imbalance increases as the day progresses. It is discussed that this probably reflects reduced effort allocation, ensuing from disengagement from the work demands. (C) 2001 Elsevier Science B.V. All rights reserved.

This study investigates the hypothesis that long lasting mental work demands are reflected in after-effects on attention demanding post-test probe tasks. Sixteen subjects were engaged in 2 simulated workdays consisting of mentally demanding tasks. On the difficult day the afternoon consisted of highly demanding information processing tasks; on the easy day the demands during the afternoon were low. The mornings of both days were equally demanding. At the start (pre-test) and the end (post-test) of both days, after 5 min (immediate post-test) as well as after approximately 2 h of recuperation (delayed post-test), a probe task was carried out. A memory-search task (varied mapping) is used as probe task. After-effects were expected in terms of a shift in the ratio between performance and effort on the post-test probe tasks compared with the pre-test probe task. Performance measures were reaction time and errors; effort was indicated by heart rate variability in the 0.07-0. 14 Hz band, referred to as 0.1 Hz component. Dayload manipulation appeared to be effective because of the load-related differences between the urinary excretion rates of adrenaline during both afternoons. Compared with the pre-test, only the number of errors was significantly increased in the post-test, carried out immediately at the end of the difficult afternoon. However, compared with the easy day, in the delayed post-test probe task after the difficult day, subjects tended to shorten reaction times, made significantly more errors, and invested significantly less effort. Moreover, at that time they felt more fatigued and deactivated as indicated by the results of the 'Scale of Experienced Load' (SEB) (fatigue) and 'Groninger Adjective Checklist' (GACL) (mood) questionnaires. The observed shift towards low-effort, more 'risky' task strategies in the post-tests fits well with Hockey's (1993) fatigue after-effects degradation pattern expected after periods of high workload. The repeated measurement of the relation of performance, effort and feelings reveals the dynamics of the pattern of fatigue after-effects over the (recovery) time.

Two experiments were carried out in a driving simulator in order to study driving behaviour in reduced visibility conditions. Both studies show that drivers maintain larger time headways when preview is limited. The results suggest that the adaptation of time headway was related to difficulty of anticipation rather than perceptual degradation due to reduced visibility. Drivers who were instructed to drive on a fixed time schedule did not increase their time headway in adverse visibility circumstances. However, they reacted very accurately to decelerations of lead cars, which prevented the occurrence of critical situations. In general, the results indicate that drivers apply a hierarchy of adaptive strategies which are aimed at the control of time pressure in driving. In normal visibility conditions, drivers adopt an anticipatory driving strategy. When the possibilities for anticipation are reduced, drivers compensate by means of speed reductions and increases in time headway, in order to increase the time available to react to potential threats. When this compensatory strategy is impossible or undesirable, drivers have to maintain high alertness in order to react accurately to unpredictable hazardous events. This strategy imposes a high time pressure on the driver. Presumably, drivers try to restrict time pressure and therefore the effort costs of driving when they have the opportunity to do so.

It is well known that chronically elevated catecholamine excretion rates are associated with health problems, indicating the importance of recovery after work. In 28 male truck drivers, unwinding after work was found to be insufficient. The resulting spillover of sympathoadrenal activation, as assessed by urinary excretion rate of adrenaline and noradrenaline, was significantly related to self-reported psychosomatic health complaints. Age had a significant effect on spillover of noradrenaline, whereas this personal factor was only marginally significant for adrenaline. This study shows that elevated sympathoadrenal activation after work, and not only increased reactivity during work, causes health problems, although it is also plausible that young and healthy drivers are able to unwind more quickly than older drivers with psychosomatic complaints. (C) 1998 John Wiley & Sons, Ltd.

Adhering to the schedule, providing service to passengers, and driving safely are among the most important psychosocial demands of the bus driver's job. The ways bus drivers cope with these varying and conflicting demands are addressed in this article, which uses data from 4 interrelated studies. In a large-scale questionnaire study (Study 1), behavioral styles in coping with these psychosocial demands were identified. Next, in Studies 2 and 3, the relations of these styles with well-being and health status were examined. Study 4 addressed the coping process during work itself by examining the relations among objective workload indicators, perceived effort, and psychophysiological stress reactions during work. (PsycINFO Database Record (c) 2016 APA, all rights reserved)

Used the passive-active dimension of the job demand–control model (T. Theorell and R. A. Karasek, see record 83:28881) to examine the impact of behavioral factors on the exposure to and actual uptake of airborne lead in 2 lead exposed populations of male workers (18 from an electric accumulator factors and 18 from a lead smeltery) and to ascertain work-related determinants of hygienic behavior. Environmental exposure was assessed by measurement of the concentration of lead dust in ambient air at the workplace, and the intake of lead was assessed by measurement of the lead in blood level. In the work environment of Ss in active jobs, lower concentrations of lead in air were measures, but higher levels of lead in blood were observed in these workers. The opposite was true of workers in passive jobs. Differences in hygienic behavior (e.g., use of protective equipment) at work may explain these results. (PsycINFO Database Record (c) 2016 APA, all rights reserved)

The performance and mental effort in a memory search task were studied in relation to length of preceding working times and the scheduling of intermittent rest pauses during work. Performance was measured by reaction time and percentage of missed signals. Mental effort was measured by means of the 0.10 Hz component in the spectral analysis of the heart rhythm signal. It was found that subjects protected their performance by spending more effort in the more unfavourable conditions: after several hours of work and after continuous work without breaks. In the most unfavourable condition, after 8 hours of work combined with sleep loss, the efficiency of the information processing was broken down. Performance was no longer protected by effort. This phenomenon is interpreted as a serious sign of mental fatigue.

Objective: To investigate to what extent vocational rehabilitation and working on a trial basis have an impact on employment after rehabilitation.Design: Follow-up survey, conducted in 1991, among all patients, aged 14 to 64, who were treated between 1984 and 1987. Setting: An out-clinic department of a rehabilitation center in the west of The Netherlands.Subjects: 395 patients (59% of the original sample) participated in the study. They suffer from musculoskeletal impairments due to back pain (41%), brain injury (20%), neurological disorder (12%), trauma to the upper and/or lower extremities (8%), rheumatoid arthritis (7%), or other disorders (12%). No differences were found between those who did and those who did not respond with regard to age, gender, marital status, disorder, work experience, and participation in vocational rehabilitation.Main Outcome Measure: Odds ratio of having a paid job after rehabilitation.Results: Participation in vocational rehabilitation and working on a trial basis depends on age, gender, work experience, and disorder. When statistically controlled for these variables vocational rehabilitation (odds ratio 1.96; 95% confidence interval 1.12 to 3.42) and working on a trial basis (odds ratio 3.26; 95% confidence interval 1.74 to 6.11) proved to have a significant impact on employment after rehabilitation.Conclusions: The findings suggest that rehabilitation programs that aim specifically at promoting employment for people with disabilities are effective, in particular when they take place in both a laboratory and a natural setting. The validity of this suggestion must be further tested by means of an experimental design. (C) 1995 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

Background: Plasma prolactin levels are sensitive to dopamine and serotonin function, and fatigue. Low cortisol, dopamine and/or serotonin may be involved in burnout and detachment. Methods: In this double-blind within-subject study, we treated 9 female burnout subjects and 9 controls with 35 mg cortisol and placebo orally. We measured state affect and plasma prolactin, oxytocin, cortisol and adrenocorticotropic hormone levels, and administered an attachment questionnaire. Results: The burnout subjects displayed an extreme distribution of basal prolactin levels, displaying higher or lower levels compared to the controls. The low prolactin burnouts had profoundly low attachment scores and tended to have low oxytocin levels. The high prolactin burnout subjects tended to show cortisol-induced decreased prolactin and fatigue, and increased vigor. Conclusion: Results are consistent with the hypothesis that burnout subjects are either characterized by low serotonergic function or by low dopaminergic function, and that the latter group benefits from cortisol replacement. These preliminary results suggest that differentiating between two syndromes may resolve inconsistencies in research on burnout, and be necessary for selecting the right treatment strategy.

Previous results suggest that both cortisol. mobilization and the error-related negativity (ERN/Ne) reflect goal engagement, i.e. the mobilization and allocation of attentional and physiological resources. Personality measures of negative affectivity have been associated both to high cortisol levels and large ERN/Ne amplitudes. However, measures of positive social adaptation and agreeableness have also been related to high cortisol levels and large ERN/Ne amplitudes. We hypothesized that, as long as they relate to concerns over social evaluation and mistakes, both personality measures reflecting positive affectivity (e.g. agreeableness) and those reflecting negative affectivity (e.g. behavioral shame proneness) would be associated with an increased likelihood of high task engagement, and hence to increased cortisol mobilization and ERN/Ne amplitudes. We had female subjects perform a flanker task while EEG was recorded. Additionally, the subjects fitted out questionnaires measuring mood and personality, and salivary cortisol immediately before and after task performance was measured. The overall pattern of relationships between our measures supports the hypothesis that cortisol. mobilization and ERN/Ne amplitude reflect task engagement, and both relate positively to each other and to the personality traits agreeableness and behavioral shame proneness. We discuss the potential importance of engagement-disengagement and of concerns over social evaluation for research on psychopathology, stress and the ERN/Ne. (c) 2006 Elsevier Ltd. All rights reserved.

The effects of mental fatigue on attention were assessed. Subjects performed a visual attention task for 3 h without rest. Subjective levels of fatigue, performance measures and EEG were recorded. Subjective fatigue ratings, as well as theta and lower-alpha EEG band power increased, suggesting that the 3 h of task performance resulted in an increase in fatigue. Reaction times, misses and false alarms increased with time on task, indicating decreased performance efficiency in fatigued subjects. Subjects were unable to inhibit automatic shifting of attention to irrelevant stimuli, reflected by a larger negativity in the N1 latency range for irrelevant, compared to relevant stimuli. This difference in negativity was unaffected by time on task. However, N1 and N2b amplitude did change with time on task: NI amplitude decreased, and the difference in N2b amplitude between relevant and irrelevant stimuli (larger N2b amplitude evoked by relevant stimuli) decreased with time on task. The results indicate a dissociation in the effects of mental fatigue on goal-directed (top-down) and stimulus-driven (bottom-up) attention: mental fatigue results in a reduction in goal-directed attention, leaving subjects performing in a more stimulus-driven fashion. (c) 2005 Elsevier B.V All rights reserved.

The acute effects of cortisol (35 mg) administration in 11 healthy male volunteers on resting frontal EEG asymmetry measured in the alpha band were investigated, using a within-subjects double-blind design. Results were indicative of a relative increase of right frontal activity with cortisol. This pattern of activity is similar to the deviant pattern that has been reported in patients suffering from depression, a condition often accompanied by elevated plasma cortisol levels. The significant effect on frontal asymmetry provides convergent support for our hypothesis, based upon previous results, that sustained (> 30 minutes after stress termination) relative high levels of cortisol inhibit approach motivation. (c) 2004 Elsevier B.V. All rights reserved.

In this study we examined whether the effects of mental fatigue on behaviour are due to reduced action monitoring as indexed by the error related negativity (Ne/ERN), N2 and contingent negative variation (CNV) event-related potential (ERP) components. Therefore, we had Subjects perform a task, which required a high degree of action monitoring, continuously for 2 h. In addition we tried to relate the observed behavioural and electrophysiological changes to motivational processes and individual differences.Changes in task performance due to fatigue were accompanied by a decrease in Ne/ERN and N2 amplitude, reflecting impaired action monitoring, as well as a decrease in CNV amplitude which reflects reduced response preparation with increasing fatigue. Increasing the motivational level of our subjects resulted in changes in behaviour and brain activity that were different for individual subjects. Subjects that increased their performance accuracy displayed an increase in Ne/ERN amplitude, while subjects that increased their response speed displayed an increase in CNV amplitude. We will discuss the effects prolonged task performance on the behavioural and physiological indices of action monitoring, as well as the relationship between fatigue, motivation and individual differences. (c) 2005 Elsevier B.V. All rights reserved.

In a recent study we investigated the acute effects of cortisol administration in healthy male volunteers on free recall of pleasant, unpleasant, and neutral nouns using a between-subjects double-blind placebo-controlled design. The volunteers were administered 10 mg of hydrocortisone or placebo between 9:00 and 10:30. Two hours after administration of cortisol a decline in recall of neutral and pleasant words was found, while recall of unpleasant words did not change. These results are consistent with a possible inhibitory influence of cortisol on a prefrontal dopaminergic mechanism involved in approach and positivity bias. In this paper we first explain why this interpretation would predict recall of pleasant words from recency positions to be especially sensitive to cortisol administration. Comparing primacy and recency recall of pleasant and unpleasant words, there proved to be a selective decline in recall of pleasant recency words. These results did not appear to stem from differences in recall strategies between our groups of volunteers. (C) 2003 Elsevier Ltd. All rights reserved.

To stress or relax: neurochemical aspects of activity and rest To stress or relax: neurochemical aspects of activity and rest M. Tops, M.M. Lorist, A.A. Wijers & T.F. Meijman, Gedrag & Organisatie, volume 17, February 2004, nr. 1, pp. 32-42. In this paper we formulate ideas about acute and chronic fatigue (especially burnout) in terms of brain neuromodulator functions. We describe dopaminergic, serotonergic and norepinephrinergic functions in energy expenditure and their role in the initiation and maintenance of behavior. We specifically focus on a dopaminergic approach-system, since there is accumulating evidence that dopaminergic systems play a central role in the symptomotology of fatigue. We argue that many symptoms of both acute fatigue and burnout can be seen as reflecting a decreased approach-motivation. Within the neuromodulator framework we propose two possible mechanisms for the development of burnout. We hope that our attempt to offer a physiological substrate for psychological ideas concerning fatigue and burnout will lead to new insights at a more applied level.

When drivers perform additional tasks while driving, research shows conflicting results: primary driving performance may deteriorate but adaptive changes such as reducing driving speed have also been noted. We hypothesized that the nature of the secondary task may be important: drivers may give more priority to tasks that serve goals of the driving task itself, for example route finding, than tasks not directly relevant for driving, for example tuning the radio. The main objective of the present driving simulator study was to test this hypothesis. Twenty subjects performed two different subsidiary tasks while driving through two levels of traffic density: a working memory (WM) task and a map reading (MAP) task. It was hypothesized that in high task demand situations, the WM task, irrelevant for the driving task, would be neglected more than the MAP task. The results confirmed the hypothesis: in MAP conditions, the WM task was indeed neglected, but map reading resulted in more swerving, indicating that the subjects looked at the map despite the high task demands. It is concluded that drivers will be highly motivated to get route information, and RG systems should therefore present their information in a readily understandable format.

During fatiguing submaximal contractions a constant force production can be obtained at the cost of an increasing central command intensity. Little is known about the interaction between the underlying central mechanisms driving motor behaviour and cognitive functions. To address this issue, subjects performed four tasks: an auditory choice reaction task (CRT), a CRT simultaneously with a fatiguing or a non-fatiguing submaximal muscle contraction task, and a fatiguing submaximal contraction task alone. Results showed that performance in the single-CRT condition was relatively stable. However, in the fatiguing dual-task condition, performance levels in the cognitive CRT deteriorated drastically with time-on-task. Moreover, in the fatiguing dual-task condition the rise in force variability was significantly larger than during the fatiguing submaximal contraction alone. Thus, our results indicate a mutual interaction between cognitive functions and the central mechanisms driving motor behaviour during fatigue. The precise nature of this interference, and at what level this interaction takes place is still unknown.

Objectives: The purpose of this cross-sectional study with repeated measurements was to find out to what extent neuroendocrine reactivity during work and neuroendocrine recovery from work, and work characteristics, are related to subjective need for recovery and perceived health status. Methods: Neuroendocrine reactivity and recovery were studied in 59 subjects by measuring urinary adrenaline and cortisol repeatedly during five consecutive days. Measures of work characteristics, subjective need for recovery, and health status were obtained by self-reports. Two hierarchical multiple linear regression analyses were performed. Results: The work characteristics alone explained 39% and 28% of the variation in subjective need for recovery and health status, respectively, while these figures rose to 49% and 53% in the full models. Significant neuroendocrine contributors were found for cortisol in reactivity during work and recovery immediately after work and recovery during the day off-work, and for adrenaline in baseline level and recovery during the day off-work. Job characteristics contributed significantly as well. Conclusion: Both neuroendocrine measures and work characteristics were predictors for the amount of perceived need for recovery after work as well as for health status. The results are consistent with the cognitive activation theory of stress. (C) 2001 Elsevier Science Inc. All rights reserved.

Item does not contain fulltext An experiment was carried out in a driving simulator in order to study time-on-task effects in driving with special attention to distance keeping and hazard avoidance performance. As expected, increases of fatigue in the course of sustained performance were associated with a deterioration of perceptual-motor performance and an increase of safety margins. In general, the results indicate that performance in less central task components such as steering deteriorates in the course of time, whereas performance in high-priority sub-tasks such as hazard avoidance remains intact. Time-schedule instructions disrupted the adaptation of safety margins in prolonged driving. This study has practical implications for the design of driver impairment monitoring systems

The effects of mental fatigue on planning and preparation for future actions were examined, using a task switching paradigm. Fatigue was induced by “time on task,” with subjects performing a switch task continuously for 2 hr. Subjects had to alternate between tasks on every second trial, so that a new task set was required on every second trial. Manipulations of response–stimulus intervals (RSIs) were used to examine whether subjects prepared themselves for the task change. Behavioral measurements, event-related potentials (ERPs), and mood questionnaires were used to assess the effects of mental fatigue. Reaction times (RTs) were faster on trials in which no change in task set was required in comparison with switch trials, requiring a new task set. Long RSIs were used efficiently to prepare for the processing of subsequent stimuli. With increasing mental fatigue, preparation processes seemed to become less adequate and the number of errors increased. A clear poststimulus parietal negativity was observed on repetition trials, which reduced with time on task. This attention-related component was less pronounced in switch trials; instead, ERPs elicited in switch trials showed a clear frontal negativity. This negativity was also diminished by time on task. ERP differences between repetition and switch trials became smaller with increasing time on task.

The present study was designed to elucidate the effect of depressive symptomatology on the cortisol response to strenuous exercise. Thirteen healthy, post-menopausal women participated in this study. The results show that acute bicycle exercise activates the hypothalamic-pituitary-adrenal (HPA) axis resulting in rapid increases in plasma cortisol. Concerning the effect of depressive symptomatology on cortisol release during physical performance, we found a trend toward a negative relation between the level of depression and the change in cortisol measured after termination of the exercise, but it failed to reach statistical significance, probably due to the small sample size. Interestingly, we found a significant negative correlation between basal cortisol levels and cortisol release to the exercise protocol. Although this finding is preliminary, it seems to suggest that a sustained activation of the HPA axis may coincide with an adrenal insufficiency in response to physical performance of post-menopausal women.

Item does not contain fulltext Driving is a task that requires the timely detection of critical events and relevant changes in traffic circumstances. Adaptation of speed and safety margins allows drivers to control the time available to react to potential hazards. One of the basic safety margins in driving is the time headway preserved with respect to cars ahead. To avoid rear-end collisions, drivers have to detect decelerations of lead cars. It can be assumed that fast or abrupt decelerations of the lead car are detected faster than slow or gradual decelerations. Moreover, expected decelerations are presumably detected faster than unexpected decelerations. Drivers' responses to rather abrupt and more gradual decelerations of the lead were investigated in a driving simulator. Situational traffic cues were used to manipulate the driver's expectations. Drivers adjusted the timing of their responses very well to the level of deceleration of the lead car. If cues in the environment indicated that the lead car was likely to decelerate, drivers reacted faster. Moreover, drivers increased their headway before the lead car actually started to decelerate, which can be considered an anticipatory response. In general, anticipation allows drivers to maintain their preferred headway and control time pressure in driving.

Two groups of six city bus drivers whose absence rate differed during the previous year were studied. Catecholamine (adrenaline, noradrenaline and dopamine) excretion rates were measured from urine samples obtained at 3-5-hour intervals over 2 working days and, for control purposes, over the first and second consecutive free days. After 3-5-hour periods of work heart rate variability was studied in laboratory conditions. In addition self-assessed workload was measured. As a major result differential neuro-endocrine and cardiovascular reactivity was found.

Car drivers appear to reduce their driving speed in high task demand situations. Summala's [Safety Sci. 22 (1996) 103–117]; [in: J.A. Rothengatter, & E. Carbonell Vaya (Eds.), Traffic and Transport Psychology: Theory and Application, Pergamon, Oxford, 1997, pp. 41–52] model of behavioural adaptation (MBA) also assumes that drivers increase speed in low task demand situations or attend to additional tasks more. The present study investigated the relation between driving speed and task demands in simulated driving. Participants were observed under three speed conditions, driving fast, driving as if taking a driving test, and following a fast-driving car. The same route was driven twice under each of these speed conditions: once with and once without the concurrent performance of an auditory short-term memory task. All other things being equal, driving fast required more effort than driving more slowly, which was not compensated for by better memory performance. This refutes one assumption of the MBA. When following a fast-driving car, participants invested less effort than when driving fast. As auditory route guidance messages were embedded within the memory task, participants were forced to attend the memory task in all rides of the Fast and Accurate conditions, but not in the Car Following conditions. This can also explain why the memory task had no effect on cognitive effort. It is concluded that car drivers prioritise their task goals.