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PubMed1998

Effects of signal probability on individual differences in vigilance.

Decrements in the proportion of signals detected over time on task and large individual differences in performance are typical findings in studies of vigilance. This study investigates the effects of signal probability on individual differences in vigilance performance. Participants monitored stimulus events on computer displays over 2-h periods at three signal probability levels (.01, .04, & .12). Results were analyzed between groups, within groups, and within subjects. Detection decrements were found to be inversely related to signal probability levels across groups. High signal probabilities generated consistent within-group and within-subject performance, whereas low probabilities generated both lower performance and larger within-subject variance. This relationship between signal probability and within-group and within-subject variance has not been previously demonstrated. Future investigations should focus on the sources of both between-subjects and within-subject variation in vigilance performance in order to identify optimal interventions. Actual or potential applications include designing work to minimize vigilance decrement and maximize human performance under conditions that require sustained attention.

Analysis of Variance↗
PubMed1972

Signal frequency and shock probability as determinants of prolonged vigilance performance in rhesus monkeys.

The effects of changing signal frequency on a prolonged vigilance task were investigated by systematically increasing the average inter-trial interval between successive signals. During a 6-hr watch, vigilance performance remained constant when the rate of signal presentation was 40, 20, and 10 per hour. When the rate of signal presentation was reduced to 7 or 4 per hour, marked decrements in detection performance were observed. Similar vigilance decrements occurred when the average rate of signals per hour was kept constant (10 per hour) and the probability of receiving a shock for missing a signal was systematically varied. The results of this study indicate the importance of reinforcement factors in the control and maintenance of vigilance performance.

Animals↗
PubMed2001

Post-marketing surveillance and vigilance for medical devices: the European approach.

The extent to which the medical device manufacturers are responsible for actively monitoring the performance of their products after they have successfully passed the rigorous pre-market approval process has always been a matter of diverse opinion. Within Europe, the law is unhelpfully vague on this point. While there are some comparatively clear obligations for reporting incidents to the authorities (known as the 'vigilance system'), little detail is given on how diligently the manufacturer should try to find out about such incidents. In the early stages of the European Community Directives covering medical devices, there was much emphasis upon formulating guidance to help interpret the vigilance reporting requirements. It is, however, only recently that attention has turned to attempting to clarify what is expected from post-marketing surveillance (PMS) in its broader sense. This article discuses both the vigilance and PMS processes and outlines the currently available European, and particularly UK, guidance documents which are aimed at promoting a more level playing field across industry where these activities are concerned. In particular, it explains the principle differences between vigilance and post-marketing surveillance: the former being the reporting of adverse incidents by manufacturers to the regulatory authorities and their subsequent sharing of key incident data between each other; the latter being the process by which information on overall devise performance is captured, analysed and acted upon. Nevertheless, it is still a struggle to gain widespread appreciation that these two activities are not in fact one and the same.

Equipment and Supplies↗
PubMed2005

Perspectives on the use of data mining in pharmaco-vigilance.

In the last 5 years, regulatory agencies and drug monitoring centres have been developing computerised data-mining methods to better identify reporting relationships in spontaneous reporting databases that could signal possible adverse drug reactions. At present, there are no guidelines or standards for the use of these methods in routine pharmaco-vigilance. In 2003, a group of statisticians, pharmaco-epidemiologists and pharmaco-vigilance professionals from the pharmaceutical industry and the US FDA formed the Pharmaceutical Research and Manufacturers of America-FDA Collaborative Working Group on Safety Evaluation Tools to review best practices for the use of these methods.In this paper, we provide an overview of: (i) the statistical and operational attributes of several currently used methods and their strengths and limitations; (ii) information about the characteristics of various postmarketing safety databases with which these tools can be deployed; (iii) analytical considerations for using safety data-mining methods and interpreting the results; and (iv) points to consider in integration of safety data mining with traditional pharmaco-vigilance methods. Perspectives from both the FDA and the industry are provided. Data mining is a potentially useful adjunct to traditional pharmaco-vigilance methods. The results of data mining should be viewed as hypothesis generating and should be evaluated in the context of other relevant data. The availability of a publicly accessible global safety database, which is updated on a frequent basis, would further enhance detection and communication about safety issues.

Adverse Drug Reaction Reporting Systems↗
PubMed2006

Effects of acute simulated microgravity on nocturnal sleep, daytime vigilance, and psychomotor performance: comparison of horizontal and 6 degrees head-down bed rest.

This study examined the effect of acute simulated microgravity on nocturnal sleep, daytime vigilance, and psychomotor performance. Each of 7 volunteers were maintained for 3 days of head-down and horizontal bed rest in a counter-balanced design. Assessment measures were polysomnographic recordings on the first night and performance on psychophysiological tasks on the second day involving subjective and objective vigilance, P300, simple reaction time tasks, and dual performance tasks. No clear difference in sleep structure was observed between the head-down and horizontal conditions, except for a slight decrease in Stage 4 for head-down. Both subjective and objective daytime vigilance, P300, and the simple RT task showed no statistical difference, although tracking performance on the dual task showed deterioration at 10:00 for the head-down condition. These results suggest that nocturnal sleep, daytime vigilance, and psychophysiological functions were not disturbed in head-down sleep conditions, although there was a mild deterioration of higher attentional function in the morning.

Adult↗
PubMed1976

Attentiveness in behaviorally deviant and nondeviant children: I. Auditory vigilance performance.

The present study examined the vigilance performance of 16 behaviorally deviant and 16 nodeviant children and suggested that the vigilance paradigm might serve as a basis for a standardized test of continuous attention in children. The deviant and nondeviant children performed an auditory vigilance task administered on two separate occasions, 4 days apart. Performance during the first administration of the task deteriorated significantly for the deviant children as a function of time but not for the nondeviant ones. This finding was consistent with several prior clinical studies with children and suggested that the behaviorally deviant children were relatively less able to maintain a continuous level of attention. In addition, the vigilance procedure yielded relatively high test-retest reliability coefficients for both groups of children as well as performance which tended to vary as a function of chronological age.

Attention↗
PubMed2000

A spatial model of antipredator vigilance.

Many species of animals have to perform two contradictory tasks: feeding, and avoiding becoming food for others. A large number of theoretical and empirical studies have investigated the trade-off between feeding and antipredator vigilance, especially in birds. An important factor which has been neglected in these studies is that of the area occupied by the flock. If individuals feed close together, competition increases and feeding rates decrease. However, if individuals space themselves widely, then vigilance efficiency goes down and there is an increased predation risk. We develop a vigilance model which allows birds to control the area the flock occupies as well as their vigilance rate. The optimal strategy is found for the birds under a variety of environmental conditions. In particular the effect of each environmental parameter on this optimum is considered in turn. How the model can be adapted for different bird species is also investigated.

Animals↗
PubMed2000

Paclitaxel does not cause central nervous adverse effects: a prospective vigilance-controlled EEG mapping study in ovarian cancer patients.

BACKGROUND: The objective of this study was to evaluate potential adverse effects of paclitaxel-containing chemotherapy on the central nervous system in women with ovarian cancer. METHODS: Twenty-eight women with histologically confirmed epithelial ovarian carcinoma and treated with combination chemotherapy consisting of paclitaxel and carboplatin were entered into the study. Patients were tested with vigilance-controlled EEG before and after chemotherapy. Additionally, a battery of neuropsychologic tests before, after 3 cycles and at the end of the chemotherapy were performed. RESULTS: Twenty of the 28 patients responded to chemotherapy (71%). Eleven patients (39%) developed peripheral neurotoxicity. A reduced vigilance in patients with ovarian cancer prior to chemotherapy compared to healthy controls was observed (clearly demonstrated by an attenuated total power, a decrease in fast alpha and slow beta activity, an increase in delta and theta activity as well as a deceleration of the centroid of the total power spectrum). On the other hand, an improved vigilance in patients with ovarian cancer treated with paclitaxel/carboplatin was observed (demonstrated by an increase in total power and an increase in beta power, being more pronounced in the right than in the left hemisphere, between pre- and post-treatment). The results of EEG mapping concurred with those of psychometric tests. The test results did not deteriorate during chemotherapy. A statistically significant improvement in the alphabetical crossout test from the first to the third measurement was observed, indicating an improvement in short-term attention, concentration and the constancy of work during chemotherapy. CONCLUSIONS: Combination chemotherapy consisting of paclitaxel and carboplatin does not cause encephalopathy, but a trend towards an improved vigilance and an improvement of short-term attention and concentration was observed in patients with ovarian cancer after chemotherapy.

Adult↗
PubMed1999

[Assessment of vigilance for patients with sleep disordered breathing].

OBJECTIVE: Assessment of vigilance for patients with sleep disordered breathing. METHODS: Vigilance of the patients referred to sleep study for suspected sleep disorders was evaluated prospectively by a computerized driving simulator SteerClear before (evening) and after (next morning) nocturnal sleep study. The vigilance was quantified by means of the averaged percentages of obstacle hitting made during the evening and the morning driving test, abbreviated as %Hm. Controls included 11 normal volunteers. Kruskal-Wallis ANOVA by Rank was used to compare the %Hm in patients with that in normal controls; Spearman Rank Correlation was used to analyze the relationship between %Hm and parameters obtained from sleep study. RESULTS: The %Hm in normal subjects and in patients were (expressed as median and range): normal subjects 0.6 (0 - 2.5), n = 11; sleep snoring 1.1 (0.2 - 2.0), n = 7; obstructive sleep apnea syndrome (OSAS) 2.2 (0.2 - 7.7), n = 22; central sleep apnea syndrome (CSAS) 2.7 (0.9 - 5.4), n = 6. The %Hm of the patients with OSAS and CSAS but not the patients with sleep snoring (P > 0.05) was significantly higher than that of normal subjects (P < 0.05). Among the normal subjects, the patients with OSAS or with sleep snoring, there existed a significant correlation between the %Hm and the percentage of cumulated time spent at the oxygen saturation below 90% (r = 0.41, n = 40, P < 0.05), whereas the %Hm was not correlated to apnea/hypopnea index (r = 0.22, n = 40, P > 0.05) nor to arousal index (r = 0.10, n = 17, P > 0.05). CONCLUSIONS: The vigilance of the patients with OSAS or CSAS but not those only with sleep snoring is impaired, the impairment may relevant to the oxygen desaturation during their sleep.

Adult↗
PubMed2003

Level of vigilance influences licking frequency in rats.

In rats, the basic licking rhythm is generated by the central pattern generator located in the brainstem. Nevertheless, the licking frequency can be regulated between about 7.5 and 4 Hz by changing the drinking conditions. If these conditions are kept constant, the licking frequency can be influenced only to a minor degree by factors such as deprivation level, type of solution, and phase of the session. The aim of our study was to compare the licking frequency of rats at different levels of vigilance. We investigated spontaneous licking of rats by an electrical lick sensor; parallel behavior monitoring was also performed. Animals kept in a stable environment and showing a lower level of vigilance licked at a rate of 5.96 Hz, fully vigilant rats licked significantly more rapidly at a frequency 6.57 Hz. The fastest rate of licking (6.49 Hz and 6.82 Hz, respectively) was encountered in alert rats under a mild stress caused by the presence of a second animal in the experimental box. The vigilance level is thus another factor affecting the licking rate of rats that should be taken into account in behavioral licking experiments.

Animals↗
PubMed2003

Clockwise and counterclockwise rotating shifts: effects on vigilance and performance.

INTRODUCTION: Arguments against counterclockwise shift schedules, such as those used in air traffic control, are prevalent in the literature; however, few studies have examined direction of rotation in rapidly rotating schedules. The present study directly compared clockwise (CW) and counterclockwise (CCW) rapidly rotating shiftwork schedules on measures of complex and vigilance task performance. METHODS: Participants (n = 28) worked day shifts for the first week of the study (0800-1600 h), followed by 2 wk of either a CW (n = 14) or CCW (n = 14) shiftwork schedule. Participants completed three 1.5-h sessions on the Multiple Task Performance Battery (MTPB) on each shift. Each session contained active- and passive-task components. In addition, participants completed a 0.5-h Bakan Vigilance Test at the beginning and end of each shift. RESULTS: A three-way, rotation condition by shift by session interaction (F (8,19) = 3.0, p < 0.05) for the active task composite scores and a rotation condition by shift interaction (F (4,23) = 6.2, p < 0.05) for the Bakan Vigilance Task indicated that effects of rotation condition were modulated by shift type, such that on particular shifts, performance in the CCW rotation was actually better than in the CW rotation. DISCUSSION: These data do not support the hypothesis that a CW rotation will result in better outcomes on complex or vigilance task performance. The results of this study indicate that two problem areas in both CW and CCW rapidly rotating shift schedules are early morning and midnight shifts.

Aviation↗
PubMed2003

Sleep, vigilance and cognition in postmenopausal women: placebo-controlled studies with 2 mg estradiol valerate, with and without 3 mg dienogest.

OBJECTIVE: To determine the effects in postmenopausal women with insomnia of hormone replacement therapy (HRT) with 2 mg estradiol valerate (E2V) alone, or in combination with 3 mg dienogest (DNG), in the context of the introduction of the novel preparation Climodien (2 mg E2V/2 mg DNG) (Schering AG, Berlin, Germany). METHODS: Parallel groups of women with insomnia related to the postmenopausal syndrome were randomized to 2 months' treatment with 2 mg E2V, 2 mg E2V/3 mg DNG or placebo (respectively, n = 17, 16, 16). Patients were then studied with techniques for assessing sleep quality, vigilance and cognition. Sleep quality was determined subjectively by means of the questionnaire-based sleep and awakening quality scale (SSA), and objectively with polysomnography. Sleep-related breathing disorders were evaluated by means of the apnea/hypopnea index. Vigilance was measured using quantitative electroencephalography with statistical probability mapping. Cognition (speed of information processing, cognition processing capacity and perceptual processing resources) was studied using the techniques of auditory event-related potentials (P300 latency and amplitude). RESULTS AND CONCLUSIONS: Treatment with 2 mg E2V and 2 mg E2V/3 mg DNG significantly improved subjective sleep quality and showed trends towards improvements in objective sleep quality. The combination of 2 mg E2V/3 mg DNG also improved the apnea/hypopnea index. Vigilance was slightly improved by treatment with 2 mg E2V and markedly with 2 mg E2V/3 mg DNG. Speed of information processing was improved with 2 mg EV2 and 2 mg E2V/3 mg DNG, whilst the latter also improved cognitive processing capacity and perceptual processing resources. The study provides evidence that HRT can improve sleep quality and mental functioning in postmenopausal women and that E2V/DNG combinations, such as 2 mg E2V/2 mg DNG, should be considered for this indication and also for the treatment of sleep-related breathing disorders in the menopause. The addition of dienogest to estradiol valerate did not antagonize the benefits of estradiol valerate in terms of sleep quality but rather potentiated estradiol valerate-related improvements in vigilance and some aspects of cognition.

Aged↗
PubMed2005

Eye preference for vigilance during feeding in coot Fulica atra, and geese Anser anser and Anser cygnoides.

Most research in avian brain lateralisation has been done using birds under laboratory conditions rather than natural settings. I studied eye preference during feeding in coot and geese when head position only allows use of one eye for vigilance. Birds regularly interrupt feeding to be vigilant. This behaviour is directed towards detecting predators. Recently, evidence was found that birds might perform some kind of "low-cost" vigilance even during feeding. Because coot and geese often turn their head to either side during feeding, laterality in head turning is expected to follow a consistent pattern in which the eye used for detecting predators should be less often directed towards the obstructive ground. Coot and geese were digitally videotaped and the number of pecks with either side oriented towards the ground at an angle of at least 45 degrees was counted. I found a strong bias in swan geese oriented their left eye towards the ground and thus using the right eye for vigilance during feeding. Coot showed a similar but less pronounced pattern, while in greylag geese no preference could be detected.

Animals↗
PubMed1985

Study of the long-term action of a Ginkgo biloba extract on vigilance and mental performance as determined by means of quantitative pharmaco-EEG and psychometric measurements.

The action of a Ginkgo biloba extract (rökan, Tanakan, G.B.E.) in promoting blood flow has been demonstrated in several animal and human pharmacological studies. The aim of this present study was to estimate the action of the substance on the central nervous system in order to be able to assess its potential use as a therapeutic agent in geriatric patients with cerebral insufficiency. Quantitative pharmaco-EEG is the method of choice for studying the vigilance-promoting effects of a drug. It is incomparable for confirming the findings of behavioural and psychometric studies. 60 volunteers of either sex participated in the double-blind trial. They were aged 57-77 years and showed mental deterioration corresponding to their age. They were randomly divided into three experimental groups: 20 subjects received 3 X 40 mg/day G.B.E., 20 received 5 mg nicergoline and 20 received a placebo of similar appearance. The subjects underwent an extensive series of examinations before and 4, 8 and 12 weeks after the start of medication. Analysis of the EEG results for the whole group revealed no significant advantage of G.B.E. over the two reference substances with regard to vigilance. However, a subclassification of the subjects showed that the vigilance of those persons with a more unfavourable initial situation measured in the resting EEG could be clearly improved by chronic G.B.E. medication. This increase in vigilance was reflected at the behavioural level by an improvement of reaction times in the G.B.E. group by comparison with the reference substances.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Vigilance: a concept and a reality.

Vigilance is a word that is underused in current anesthesia practice. Attention is turning from the patient to the machine and monitor. Vigilance has a definite role in anesthesia safety and the high technology anesthesia environment only enhances the need for vigilance. This article analyzes the concept of vigilance and its implication on nurse anesthesia practice.

Attention↗
PubMed2005

Prevalence of peanut sensitization in a population of 4,737 subjects--an Allergo-Vigilance Network enquiry carried out in 2002.

A total of 4,737 people consulting allergologists were routinely tested for peanut sensitization. The study involved 84 allergologists in the Allergo-Vigilance Network over a period of 30-60 consecutive days. Investigation procedures were identical. Results classified subjects into four groups according to the clinical history and prick-tests to common inhalants: group 1: subjects suspected of having a food allergy; group 2: subjects with ongoing atopic disease; group 3: subjects with an underlying predisposition to atopy, as showed by one or more positive results to prick-tests with airborne allergens; group 4: non atopic subjects. The sensitization rates were 22.7%, 8.7%, 4%, and 0.4% respectively. Assuming that 25% of the French population is allergic the rate of sensitization to peanut in the general population should be between 1% and 2.5%. Considering a ratio of 3.3 between sensitization and clinical allergy as plausible, the prevalence of peanut allergy could be 0.3% to 0.75% of the French population. This figure is lower than that for the UK, the US and Canada (0.8% to 1.5%). The correlation between the data in this study and those from previous epidemiological studies validates the methodology used in this type of enquiry. One of the aims of the Allergo-Vigilance Network set up in 2001 is to collect data from a large number of people. We present here the results of a study carried out in 2002 by 84 allergologists in the Allergo-Vigilance Network. The primary aim was to assess the prevalence of peanut sensitization in the French population seeking treatment for various allergic disorders. The second objective was to determine whether there was any difference in risk of peanut sensitization in people with ongoing atopic disease, in those with an underlying predisposition to atopy (shown by positive prick-tests) and finally in non atopic people.

Arachis↗
PubMed1999

Predicting flock vigilance from simple passerine interactions: modelling with cellular automata.

Vigilance in flocks can be described and modelled as a plausible set of local interactions between neighbouring birds. Each bird in the modelled flock chooses to feed or to scan based solely on whether or not its neighbours are feeding or scanning. This simple model has the ability both to reproduce observations that have not been previously explained and to predict flock behaviours that might be confirmed with future field studies. Examples include simulations showing decreased vigilance with increased flock size (as observed in the field), greater time spent scanning when obstacles such as trees are present (as observed) and a coordinated feed/scan pattern (that is predicted to become increasingly coordinated when the birds look up from feeding more frequently). The numerical model also predicts that flock geometry influences vigilance. If two flocks are the same size, individuals in the one with the larger perimeter will spend more time scanning. This prediction could be tested with field studies and already has been observed empirically for two limiting cases: birds arranged in a line (high perimeters, high scan times) and birds in a circle (lower perimeters, lower scan times). As demonstrated by its multiple successes, cellular models of this type are a powerful new approach to understanding bird flock behaviours. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Group Dynamics in Top Management Teams: Groupthink, Vigilance, and Alternative Models of Organizational Failure and Success.

This study explored the heuristic value of Janis' (1982) groupthink and vigilant decision making models as explanations of failure and success in top management team decision making using the Organizational Group Dynamics Q-sort (GDQ). Top management teams of seven Fortune 500 companies were examined at two historical junctures-one when the team was successful (defined as satisfying strategic constituencies) and one when the team was unsuccessful. Results strongly supported the notion that a group' decision making process is systematically related to the outcomes experienced by the team. Ideal-type Q-sorts organized around Janis' analysis of groupthink and vigilance were substantially correlated with Q-sorts of failing and successful groups, respectively. The fit was, however, far from perfect. Ideal-type Q-sorts derived from other frameworks correlated better with the failure-success classification than did the Janis-derived ideal types. Successful groups showed some indicators of groupthink (e.g., risk-taking, cohesion, and strong, opinionated leaders), whereas unsuccessful groups showed signs of vigilance (e.g., internal debate to the point of factionalism). The results illustrate the usefulness of the GDQ for developing and empirically testing theory in organizational behavior from historical cases. Copyright 1998 Academic Press.

Journal Article↗