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Alertness

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Tzyy-ping Jung – One of the best experts on this subject based on the ideXlab platform.

  • Estimation of Alertness levels with changes in decibel scale wavelength of EEG during dual-task simulation of auditory sonar target detection
    2010 Annual International Conference of the IEEE Engineering in Medicine and Biology, 2010
    Co-Authors: Sridhar P Arjunan, Dinesh K Kumar, Tzyy-ping Jung

    Abstract:

    Changes in Alertness levels can have dire consequences for people operating and controlling motorized equipment. Past research studies have shown the relationship of Electroencephalogram (EEG) with Alertness of the person. This research reports the fractal analysis of EEG and estimation of the Alertness levels of the individual based on the changes in the maximum fractal length (MFL) of EEG. The results indicate that MFL of only 2 channels of EEG can be used to identify the loss of Alertness of the individual with mean (inverse) correlation coefficient = 0.82. This study has also reported that using the changes in MFL of EEG, the changes in Alertness level of a person was estimated with a mean correlation coefficient = 0.69.

  • Changes in decibel scale wavelength properties of EEG with Alertness levels while performing sustained attention tasks
    2009 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2009
    Co-Authors: Sridhar P Arjunan, Dinesh K Kumar, Tzyy-ping Jung

    Abstract:

    Loss of Alertness can have dire consequences for people controlling motorized equipment or for people in professions such as defense. Electroencephalogram (EEG) is known to be related to Alertness of the person, but due to high level of noise and low signal strength, the use of EEG for such applications has been considered to be unreliable. This study reports the fractal analysis of EEG and identifies the use of maximum fractal length (MFL) as a feature that is inversely correlated with the Alertness of the subject. The results show that MFL (of only single channel of EEG) indicates the loss of Alertness of the individual with mean (inverse) correlation coefficient = 3D 0.82.

  • Adaptive EEG-Based Alertness Estimation System by Using ICA-Based Fuzzy Neural Networks
    IEEE Transactions on Circuits and Systems I: Regular Papers, 2006
    Co-Authors: Li-wei Ko, Tzyy-ping Jung, I-fang Chung, Teng-yi Huang, Yu-chieh Chen, Sheng-fu Liang

    Abstract:

    Drivers’ fatigue has been implicated as a causal factor in many accidents. The development of human cognitive state monitoring system for the drivers to prevent accidents behind the steering wheel has become a major focus in the field of safety driving. It requires a technique that can continuously monitor and estimate the Alertness level of drivers. The difficulties in developing such a system are lack of significant index for detecting drowsiness and the interference of the complicated noise in a realistic and dynamic driving environment. An adaptive Alertness estimation methodology based on electroencephalogram, power spectrum analysis, independent component analysis (ICA), and fuzzy neural network (FNNs) models is proposed in this paper for continuously monitoring driver’s drowsiness level with concurrent changes in the Alertness level. A novel adaptive feature selection mechanism is developed for automatically selecting effective frequency bands of ICA components for realizing an on-line Alertness monitoring system based on the correlation analysis between the time-frequency power spectra of ICA components and the driving errors defined as the deviation between the center of the vehicle and the cruising lane in the virtual-reality driving environment. The mechanism also provides effective and efficient features that can be fed into ICA-mixture-model-based self-constructing FNN to indirectly estimate driver’s drowsiness level expressed by approximately and predicting the driving error

Edith Galy – One of the best experts on this subject based on the ideXlab platform.

  • Can the effect of low doses of alcohol on subjective and physiological Alertness of young drivers be balanced by effort?
    , 2018
    Co-Authors: Catherine Berthelon, Edith Galy

    Abstract:

    Young novice drivers have a high risk of crashes and a linear relationship has been demonstrated between blood alcohol concentration (BAC) and crash risk for this population [1, 2]. They are also over represented in crashes linked to long period of driving. Generally, it is well known that the major part of sleep (or fatigue)-related crashes takes place during the two daily periods of physiological decrease of Alertness [3]. Moreover, a monotonous road environment can influence the level of Alertness [4]. Thus, effort of novice drivers higher when Alertness is low and the lack of resources can explain this result [5]. Consequently, the aim of this work is to evaluate the combined effect of these factors of accident (alcohol and driving experience) on driving performance. The hypothesis is that an increase of effort decreases Alertness, notably when drivers lack of experience or in presence of alcohol, but could be balanced by an additional effort until a certain threshold.

  • Is the driving behaviour of young novices and young experienced drivers under alcohol linked to their perceived effort and Alertness?
    Advances in Intelligent Systems and Computing, 2018
    Co-Authors: Catherine Berthelon, Edith Galy

    Abstract:

    The aim of this study is to evaluate effort and Alertness perception and objective performance of young drivers depending on Blood Alcohol Concentration (BAC) and driving experience. Assuming that, during monotonous driving, performance should be impaired with alcohol when Alertness is low, the hypothesis was that subjective state linked to monotonous driving is modified with alcohol and produces impairment of performance depending on driving experience. Fifteen young novice drivers (18 years, two months of driving) and 15 young experience drivers (21 years, 3 years of driving) participated in three simulated driving sessions in which BACs were randomly assigned (0.0, 0.2 and 0.5 g/L). Every session took place between 2 and 4 pm, during postprandial period, around one hour after the drink. The circuit represented a typical highway road, the task was to drive during 45 min and to maintain a steady speed (110 Km/h) and a stable position on the lane. After each driving session, participants responded to Thayer scale (subjective Alertness) and to an adaptation of the NASA-TLX (only subjective effort dimension was analysed). Speed and lane position were continuously recorded. Generalized linear model were applied to data, completed with correlations. Preliminary correlation analyses showed that Alertness estimations were negatively correlated with perceived effort, stability of speed and of lateral position, notably for young novice drivers, indicating that when Alertness estimation was high, perceived effort, stability of speed and of lateral position were low. Results of generalized linear model analyses showed that young experienced drivers estimated to make less effort than young novice drivers. Moreover, a significant effect of alcohol was observed, with estimated Alertness level lower with 0.5 g/l of alcohol compared two other conditions (0.0 and 0.2 g/l). Another analysis revealed that driving performance (stability of speed and of lateral position) was determined by driving experience, with performance better for young experienced drivers than for young novice drivers, and by alcohol, with speed variation higher with 0.5 g/l than with the other two conditions. It existed too an interaction effect between perceived effort and alcohol and between Alertness and alcohol on driving performance. Thus, with 0.5 g/l of alcohol, speed variation increased with the effort, conversely with 0.2 g/l and 0.0 g/l an effort increase was linked to a speed variation decrease. On another side, an increase of subjective Alertness produced a speed increase with 0.2 g/l and 0.0 g/l only. Globally, young novice drivers seem to have more difficulties to stabilize their speed with 0.5 g/l than young experienced drivers. Thus, first effect of alcohol appears at lower doses for young novice drivers than for young experienced drivers and this result confirms our earlier works. Young novice drivers have not acquire all the competences necessary for a safe drive and to use regulatory mechanisms to preserve their driving performance. Moreover, with 0.5 g/l, an effort increase is not sufficient to maintain good performance. In summary, alcohol degrades driving performance, and especially when the effort is high, Alertness is low and drivers lack experience.

  • Are low doses of alcohol taken at 2 pm objectively and subjectively more decrement for novices drivers than for more experienced drivers ?
    , 2016
    Co-Authors: Catherine Berthelon, Edith Galy, Hugo Loeches De La Fuente

    Abstract:

    The objective was to evaluate subjective estimation and objective performance of drivers depending on Blood Alcohol Concentration (BAC) and driving experience. Assuming that during monotonous driving performance should be impaired with alcohol at a moment of Alertness decrease, the hypothesis was that this impairment would be significant greater for Young Novice Drivers (YND) than for Young Experienced Drivers (YED). 16 YND (18 years, two months of driving) and 15 YED (21 years, 3 years of driving) participated in three simulated driving sessions in which BACs were randomly assigned (0.0, 0.2 and 0.5 g/L). Every session took place between 2 and 4 pm, around one hour after the drink. The circuit represented a typical highway road, the task was to drive during 45 min and to maintain a steady speed (110 Km/h) and a stable position on the lane. After each driving session participants estimated their workload (NASA-TLX questionnaire) and their subjective Alertness (Thayer checklist). Driving performance was analysed for steps of 5 min. Globally, placebo session produced higher estimation of Alertness, lower estimation of time pressure, physical demand, frustration and effort than BAC sessions. Driving performance was also worse with alcohol. A decrease of Alertness and an increase of physical and mental effort were noted with the time-on-task. Thus, evaluation of Alertness and effort during monotonous driving task were relatively well correlated with objective performance under the influence of alcohol and with time-on-task. YND had a lower subjective Alertness level and estimate to have higher mental and physical workload than YED, their subjective performance and objective driving performance showed an effect of alcohol. YED performance and subjective evaluation are clearly sensitive to alcohol but also to time-on-task (combined effect).

Claudine Mélan – One of the best experts on this subject based on the ideXlab platform.

  • Effects of Cognitive Appraisal and Mental Workload Factors on Performance in an Arithmetic Task
    Applied Psychophysiology Biofeedback, 2015
    Co-Authors: Edith Galy, Claudine Mélan

    Abstract:

    לא נראה רלו We showed in a previous study an additive interaction between intrinsic and extraneous cognitive loads and of participants’ Alertness in an 1-back working memory task. The interaction between intrinsic and extraneous cognitive loads was only observed when participants’ Alertness was low (i.e. in the morning). As Alertness is known to reflect an individual’s general functional state, we suggested that the working memory capacity available for germane cognitive load depends on a participant’s functional state, in addition to intrinsic and extraneous loads induced by the task and task conditions. The relationships between the different load types and their assessment by specific load measures gave rise to a modified cognitive load model. The aim of the present study was to complete the model by determining to what extent and at what processing level an individual’s characteristics intervene in order to implement efficient strategies in a working memory task. Therefore, the study explored participants’ cognitive appraisal of the situation in addition to the load factors considered previously—task difficulty, time pressure and Alertness. Each participant performed a mental arithmetic task in four different cognitive load conditions (crossover of two task difficulty conditions and of two time pressure conditions), both while their Alertness was low (9 a.m.) and high (4 p.m.). Results confirmed an additive effect of task difficulty and time pressure, previously reported in the 1-back memory task, thereby lending further support to the modified cognitive load model. Further, in the high intrinsic and extraneous load condition, performance was reduced on the morning session (i.e. when Alertness was low) on one hand, and in those participants’ having a threat appraisal of the situation on the other hand. When these factors were included into the analysis, a performance drop occurred in the morning irrespective of cognitive appraisal, and with threat appraisal in the afternoon (i.e. high Alertness). Taken together, these findings indicate that mental overload can be the result of a combination of subject-related characteristics, including Alertness and cognitive appraisal, in addition to well-documented task-related components (intrinsic and extraneous load). As the factors investigated in the study are known to be critically involved in a number of real jobactivities, the findings suggest that solutions designed to reduce incidents and accidents at work should consider the situation from a global perspective, including individual characteristics, task parameters, and work organization, rather than dealing with each factor separately.

  • Differential 24-hour variation of Alertness and subjective tension in process controllers: Investigation of the relationship with body temperature and heart rate
    Chronobiology International, 2008
    Co-Authors: Magali Cariou, Edith Galy, Claudine Mélan

    Abstract:

    The effects of shift and time-on-shift on Alertness and perceived tension, as well as related physiological variables, were investigated in satellite controllers working a rapid forward rotating three-shift system. In controlled laboratory conditions, subjective tension and HR have been reported to display circadian variation and marked sensitivity to external factors. We examined whether circadian variations were masked for these particular variables in real-job conditions, unlike for Alertness and body temperature, which have been repeatedly shown to display circadian variation in these conditions. This hypothesis was tested in a repeated-measures design by collecting Alertness and tension self-reports and recording operators’ sublingual temperature on three occasions on each shift and HR continuously throughout shifts. Alertness and body temperature varied according to a typical diurnal trend; subjective tension was only enhanced on the initial recording of each shift (compared to the remaining ones), while HR displayed an intermediary trend. Intra-subject correlations revealed a positive relationship between Alertness, oral temperature, and HR, while no such relationship was found for subjective tension. These results support the hypothesis of a close dependence of Alertness and temperature, and to a lesser extent for HR, on endogenous mechanisms in this job-situation. In addition, some situation-specific factors, such as job-demand, would affect subjective tension and partially mask the circadian variations in HR.