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Vigilance Task (vigilance + task)
Selected AbstractsEffects of virtual lighting on visual performance and eye fatigueHUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 2 2002Vincent G. Duffy This study is designed to determine whether differences in eye fatigue and visual performance can be shown under varying virtual industrial lighting conditions. It is based on the results of studies of more traditional video display terminal (VDT) tasks reported in the literature. One experiment was designed to determine if the effects of virtual lighting on eye fatigue and visual performance in a simulated virtual industrial environment are similar to some other VDT tasks with varying luminance contrast. Results of a test of 20 participants in a vigilance task show that there is a significant difference in performance and eye fatigue in the virtual environment with varying virtual light conditions. These results may help designers see that performance in some virtual "lighting" conditions, for some tasks, is consistent with that in the real. However, due to the difficulties of determining the appropriate virtual objects to be considered for the luminance measures, additional research is needed to be able to generalize the results to other industrial training scenarios. A second experiment was intended to test for the luminance decrement in a VDT that was shown in recent literature. The results would have potential implications for the experiment that included a vigilance task. However, the results showed that the luminance decrement demonstrated in recent literature did not occur. These results suggest that the equipment used in the present experiments should not cause difficulty in interpreting the results of the vigilance task. © 2002 Wiley Periodicals, Inc. [source] Effects of dietary caffeine on EEG, performance and mood when rested and sleep restricted,HUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 8 2008Michael A. Keane Abstract Rationale: Until recently, little account had been taken of the confounding effects of caffeine withdrawal and withdrawal reversal when examining the net effects of dietary caffeine. Objectives: By including a manipulation involving sleep restriction, the present study aimed to extend recent findings from research in which caffeine withdrawal and withdrawal reversal were controlled. The main aims of the study were to examine the net effects of caffeine, as well as its potential restorative effects following sleep restriction, on EEG, performance and mood. Method: A randomised cross-over design was used in which 15 participants alternated weekly between ingesting placebo and caffeine (1.75,mg/kg) three times daily for four consecutive weeks following either usual sleep or sleep restriction. EEG activity was measured at 32 sites during eyes closed, eyes open and performance of a vigilance task. Results: Modest effects of caffeine were found in the delta and beta bandwidths, but no main effects of caffeine were observed in the theta or alpha bandwidths. Overall, the effects of caffeine on EEG activity were relatively few, weak and inconsistent, and no evidence was found of net restorative effects of caffeine for any outcome variables. Conclusions: The findings do not support the use of caffeine as a means for enhancing human function or as an antidote to the negative effects of sleep loss. Copyright © 2008 John Wiley & Sons, Ltd. [source] BOLD Response During Spatial Working Memory in Youth With Heavy Prenatal Alcohol ExposureALCOHOLISM, Issue 12 2009Andrea D. Spadoni Background:, Prenatal alcohol exposure has been consistently linked to neurocognitive deficits and structural brain abnormalities in affected individuals. Structural brain abnormalities observed in regions supporting spatial working memory (SWM) may contribute to observed deficits in visuospatial functioning in youth with fetal alcohol spectrum disorders (FASDs). Methods:, We used functional magnetic resonance imaging (fMRI) to assess the blood oxygen level dependent (BOLD) response in alcohol-exposed individuals during a SWM task. There were 22 young subjects (aged 10,18 years) with documented histories of heavy prenatal alcohol exposure (ALC, n = 10), and age- and sex-matched controls (CON, n = 12). Subjects performed a SWM task during fMRI that alternated between 2-back location matching (SWM) and simple attention (vigilance) conditions. Results:, Groups did not differ on task accuracy or reaction time to the SWM condition, although CON subjects had faster reaction times during the vigilance condition (617 millisecond vs. 684 millisecond, p = 0.03). Both groups showed similar overall patterns of activation to the SWM condition in expected regions encompassing bilateral dorsolateral prefrontal lobes and parietal areas. However, ALC subjects showed greater BOLD response to the demands of the SWM relative to the vigilance condition in frontal, insular, superior, and middle temporal, occipital, and subcortical regions. CON youth evidenced less increased brain activation to the SWM relative to the vigilance task in these areas (p < 0.05, clusters > 1,664 ,l). These differences remained significant after including Full Scale IQ as a covariate. Similar qualitative results were obtained after subjects taking stimulant medication were excluded from the analysis. Conclusions:, In the context of equivalent performance to a SWM task, the current results suggest that widespread increases in BOLD response in youth with FASDs could either indicate decreased efficiency of relevant brain networks, or serve as a compensatory mechanism for deficiency at neural and/or cognitive levels. In context of existing fMRI evidence of heightened prefrontal activation in response to verbal working memory and inhibition demands, the present findings may indicate that frontal structures are taxed to a greater degree during cognitive demands in individuals with FASDs. [source] Patterns of performance degradation and restoration during sleep restriction and subsequent recovery: a sleep dose-response studyJOURNAL OF SLEEP RESEARCH, Issue 1 2003Gregory Belenky SUMMARY Daytime performance changes were examined during chronic sleep restriction or augmentation and following subsequent recovery sleep. Sixty-six normal volunteers spent either 3 (n = 18), 5 (n= 16), 7 (n = 16), or 9 h (n = 16) daily time in bed (TIB) for 7 days (restriction/augmentation) followed by 3 days with 8 h daily TIB (recovery). In the 3-h group, speed (mean and fastest 10% of responses) on the psychomotor vigilance task (PVT) declined, and PVT lapses (reaction times greater than 500 ms) increased steadily across the 7 days of sleep restriction. In the 7- and 5-h groups speed initially declined, then appeared to stabilize at a reduced level; lapses were increased only in the 5-h group. In the 9-h group, speed and lapses remained at baseline levels. During recovery, PVT speed in the 7- and 5-h groups (and lapses in the 5-h group) remained at the stable, but reduced levels seen during the last days of the experimental phase, with no evidence of recovery. Speed and lapses in the 3-h group recovered rapidly following the first night of recovery sleep; however, recovery was incomplete with speed and lapses stabilizing at a level comparable with the 7- and 5-h groups. Performance in the 9-h group remained at baseline levels during the recovery phase. These results suggest that the brain adapts to chronic sleep restriction. In mild to moderate sleep restriction this adaptation is sufficient to stabilize performance, although at a reduced level. These adaptive changes are hypothesized to restrict brain operational capacity and to persist for several days after normal sleep duration is restored, delaying recovery. [source] The effects of caffeine on simulated driving, subjective alertness and sustained attentionHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 7 2001Carolyn Brice Abstract There is evidence that caffeine increases alertness and reduces fatigue. This may be especially so in low arousal situations (e.g. working at night or for prolonged hours). Caffeine has also been found to improve performance on vigilance tasks and simple tasks requiring sustained response. Again, these effects are often clearest when alertness is reduced, although there is evidence that benefits may still occur when the individual is unimpaired. Most studies to date have investigated the behavioural effects of caffeine in laboratory experiments using artificial tasks. In the current study 3,mg/kg caffeine was found to improve steering accuracy in a 1,h simulated drive. Measures of mood and performance on a sustained attention task also showed the benefits of caffeine. These findings suggest that laboratory results reflect a general benefit of caffeine that may also be observed in real-life situations. Other evidence examining the effects of caffeine on performance efficiency over the working day has shown the benefits of caffeine consumption on measures of sustained attention and alertness. This study also provided evidence suggesting that caffeine is often consumed when alertness is low to maximise alertness and performance efficiency. The implications of these findings for road safety are also considered. Copyright © 2001 John Wiley & Sons, Ltd. [source] | ||||||||||