35 research outputs found
EEG Theta Power Activity Reflects Workload among Army Combat Drivers: An Experimental Study
We thank HĂ©ctor Rieiro, Eduardo Bailon, and Jose M. Morales, (University of Granada) for
their help in data processing. We also thank Lieutenant Colonel Francisco de AsĂs Vázquez Prieto (Training and
Doctrine Command, Spanish Army) for his help in organizing the study.We aimed to evaluate the effects of mental workload variations, as a function of the road
environment, on the brain activity of army drivers performing combat and non-combat scenarios in a
light multirole vehicle dynamic simulator. Forty-one non-commissioned officers completed three
standardized driving exercises with different terrain complexities (low, medium, and high) while
we recorded their electroencephalographic (EEG) activity. We focused on variations in the theta
EEG power spectrum, a well-known index of mental workload. We also assessed performance and
subjective ratings of task load. The theta EEG power spectrum in the frontal, temporal, and occipital
areas were higher during the most complex scenarios. Performance (number of engine stops) and
subjective data supported these findings. Our findings strengthen previous results found in civilians
on the relationship between driver mental workload and the theta EEG power spectrum. This suggests
that EEG activity can give relevant insight into mental workload variations in an objective, unbiased
fashion, even during real training and/or operations. The continuous monitoring of the warfighter not
only allows instantaneous detection of over/underload but also might provide online feedback to the
system (either automated equipment or the crew) to take countermeasures and prevent fatal errors.This work was supported by Santander Bank–CEMIX UGR-MADOC (grant number PINs2018-15 to
CDP & LLDS) and the Centro Universitario de la Defensa–Zaragoza (grant numbers 2015-05 and 2017-03 to MVS).
Additional support was obtained from the Unit of Excellence on Brain, Behavior, and Health (SC2), funded by the
Excellence actions program of the University of Granada. The funding organizations had no role in the design
or conduct of this research. Research by LLDS is supported by the RamĂłn y Cajal fellowship program from the
Spanish State Research Agency (RYC-2015-17483)
Oculomotor Assessment of Diurnal Arousal Variations
Saccadic and pupillary responses are reliable indices of arousal decrement (e.g. fatigue), that might be exploited to improve work schedule guidelines. In this study, we tested the sensitivity of a short 30-s oculomotor test to detect diurnal arousal variations. Twelve participants (5 females, 7 males, 37.7+-11.9 years) volunteered to be assessed every hour (66+-20 min) for three consecutive working days, during their regular office-hours. We used a fully automated testing system, the FIT 2000 Fitness Impairment Tester (Pulse Medical Instruments Inc., Rockville, MD, USA), to measure and record saccadic peak velocity, pupil diameter, and latency and amplitude of the pupillary light reflex. In addition, we collected subjective levels of arousal using the Stanford Sleepiness Scale, and body core temperature. We analyzed the data using a linear mixed model approach for longitudinal data. Both saccadic velocity and subjective alertness decreased over the course of a day, while body core temperature increased (all p-values.05). The data also weakly suggested an increase of the pupil diameter (p 07). The findings support the use of oculomotor indices in the assessment of arousal and fatigue in applied settings
The influence of LED road stud color on driver behavior and perception along horizontal curves at nighttime
Scotopic lighting conditions (reduced level of natural light or presence of artificial lighting) may impair driving performance and, therefore, impact on road safety. Thanks to technological developments, low-cost light emitting diode (LED) studs are now being considered as an alternative and affordable pavement marking solution to assist drivers in these conditions. By helping them to maintain their vehicle within the marked lane, the studs should prevent any deterioration in driver performance when negotiating curves at nighttime. However, the few studies that investigated the impact of LED studs on driving performance produced inconsistent results, and the question of whether they actively improve driver performance remains open. Furthermore, while international road regulations allow the use of LED studs, they do not provide consistent prescriptions for their lighting color.Here, we assessed the influence of different LED lighting colors (red, white, and unlit) on longitudinal and transversal driver behavior when negotiating road curves with different radii and sense of direction. In the study, thirty-six drivers drove a dynamic virtual scenario featuring twenty-four curves. After the driving simulation, participants completed a static perception test in which they assessed each curve in terms of the perceived levels of risk, pleasantness, and arousal they experienced while driving on it.In comparison with the unlit and red lit curves, those marked with white lighting LED studs were perceived as less risky, less arousing, and more pleasant independently of the radii and curve direction. Furthermore, when entering these curves, participants tended to shift their driving trajectories towards the center of the road. This effect was most evident on the central part of the curve. Further studies are expected to corroborate these results by focusing on different road geometries and LED stud layouts, as well as testing driving behavior in controlled road field studies
The effect of traffic light spacing and signal congruency on drivers’ responses at urban intersections
Traffic lights are critical in regulating traffic flow and modulate the level of service and road user safety. As suggested by studies conducted with pedestrians, traffic light spacing and signal congruency could also impact a driver's decision-making process. However, requirements related to designing signalized intersections do not always consider the spacing between two consecutive traffic lights or the congruency of the information displayed. Here, using a classic traffic psychology paradigm, we developed a hybrid Go/No-go Flanker PC-based task to explore how traffic light spacing and signal congruency modulate drivers’ decisions in urban intersections. Real images of road intersections were edited to reproduce two specific conditions between traffic lights. Specifically, we manipulated both spacing (short vs. long) and congruency (congruent [e.g., red-red/green-green steady light] vs. incongruent [e.g., red-green/green-red steady light]). We found that incongruent information, displayed on short spacing traffic signals, delayed drivers’ responses without being detrimental to their decision-making processes. The results of this exploratory study could offer guidance to transportation engineers to simplify traffic light information readability and increase drivers’ awareness of traffic conditions and road safety
Ethical and legal challenges of automated driving: The prioritization of socio-political values
Much research on the ethics of automated driving (AD) focusses on moral decision-making processes in extreme traffic situations. However, more likely scenarios involving daily trade-offs among different values in the design and implementation of AD are also worth considering. Our main goal was to provide an in-depth analysis of how diverse experts and stakeholders prioritize different socio-political values. Through a series of workshops, semi-structured interviews, and focus groups, we assessed today's major social, ethical, and legal concerns related to AD, as well as their relative prioritization in specific near-future realistic traffic scenarios. We summarize experts’ and lay-people's opinions on the trade-offs among six socio-political values (privacy, autonomy, safety, security, performance, and costs) and present overall recommendations for the design of future AD technologies
Validation of Electroencephalographic Recordings Obtained with a Consumer-Grade, Single Dry Electrode, Low-Cost Device: A Comparative Study
The functional validity of the signal obtained with low-cost electroencephalography (EEG)
devices is still under debate. Here, we have conducted an in-depth comparison of the EEG-recordings
obtained with a medical-grade golden-cup electrodes ambulatory device, the SOMNOwatch +
EEG-6, vs those obtained with a consumer-grade, single dry electrode low-cost device, the NeuroSky
MindWave, one of the most a ordable devices currently available. We recorded EEG signals at Fp1
using the two di erent devices simultaneously on 21 participants who underwent two experimental
phases: a 12-minute resting state task (alternating two cycles of closed/open eyes periods), followed by
60-minute virtual-driving task. We evaluated the EEG recording quality by comparing the similarity
between the temporal data series, their spectra, their signal-to-noise ratio, the reliability of EEG
measurements (comparing the closed eyes periods), as well as their blink detection rate. We found
substantial agreement between signals: whereas, qualitatively, the NeuroSky MindWave presented
higher levels of noise and a biphasic shape of blinks, the similarity metric indicated that signals from
both recording devices were significantly correlated. While the NeuroSky MindWave was less reliable,
both devices had a similar blink detection rate. Overall, the NeuroSky MindWave is noise-limited,
but provides stable recordings even through long periods of time. Furthermore, its data would be of
adequate quality compared to that of conventional wet electrode EEG devices, except for a potential
calibration error and spectral differences at low frequencies.Spanish Department of Transportation, Madrid, Spain (Grant No.
SPIP2014-1426 to L.L.D.S.)A.C. is funded by a Spanish Ministry of Economy and Competitiveness
grant (PSI2016-80558-R to A.C.)S.R. is funded by an Andalusian Government Excellence Research
grant (P11-TIC-7983)L.J.F. is funded by a Spanish Ministry of Economy and Competitiveness grant
(PSI2014-53427-P) and a FundaciĂłn SĂ©neca grant (19267/PI/14)L.L.D.S. is currently supported by the
RamĂłn y Cajal fellowship program (RYC-2015-17483)C.D.-P. is currently supported by the CEIMAR
program (CEIMAR2018-2)C.D.-P. and L.L.D.S. are supported by a Santander Bank—CEMIX UGR-MADOC grant
(Project PINS 2018-15
Abnormal Capillary Vasodynamics Contribute to Ictal Neurodegeneration in Epilepsy
Seizure-driven brain damage in epilepsy accumulates over time, especially in the hippocampus, which can lead to sclerosis, cognitive decline, and death. Excitotoxicity is the prevalent model to explain ictal neurodegeneration. Current labeling technologies cannot distinguish between excitotoxicity and hypoxia, however, because they share common molecular mechanisms. This leaves open the possibility that undetected ischemic hypoxia, due to ictal blood flow restriction, could contribute to neurodegeneration previously ascribed to excitotoxicity. We tested this possibility with Confocal Laser Endomicroscopy (CLE) and novel stereological analyses in several models of epileptic mice. We found a higher number and magnitude of NG2+ mural-cell mediated capillary constrictions in the hippocampus of epileptic mice than in that of normal mice, in addition to spatial coupling between capillary constrictions and oxidative stressed neurons and neurodegeneration. These results reveal a role for hypoxia driven by capillary blood flow restriction in ictal neurodegeneration
Abnormal Capillary Vasodynamics Contribute to Ictal Neurodegeneration in Epilepsy
Seizure-driven brain damage in epilepsy accumulates over time, especially in the hippocampus, which can lead to sclerosis, cognitive decline, and death. Excitotoxicity is the prevalent model to explain ictal neurodegeneration. Current labeling technologies cannot distinguish between excitotoxicity and hypoxia, however, because they share common molecular mechanisms. This leaves open the possibility that undetected ischemic hypoxia, due to ictal blood flow restriction, could contribute to neurodegeneration previously ascribed to excitotoxicity. We tested this possibility with Confocal Laser Endomicroscopy (CLE) and novel stereological analyses in several models of epileptic mice. We found a higher number and magnitude of NG2+ mural-cell mediated capillary constrictions in the hippocampus of epileptic mice than in that of normal mice, in addition to spatial coupling between capillary constrictions and oxidative stressed neurons and neurodegeneration. These results reveal a role for hypoxia driven by capillary blood flow restriction in ictal neurodegeneration
How to take speed decisions consistent with the available sight distance using an intelligent speed adaptation system
Travelling at excessive speed increases the risk of having a road crash. Intelligent Speed Adaptation (ISA) systems might help the driver to make safe speed decisions along road sections with limited visibility. A recently
developed ISA system, called V–ISA (Hazoor et al., 2021), is able to estimate the dynamic (real-time) speed limit, based on the prevailing sight conditions and stopping distance. The V-ISA operates in the following three ways: it
can (i) display visual information, (ii) alert the driver with a warning sound, and/or (iii) intervene directly to modify and control vehicle speed. The effects of V-ISA on driving performance have yet to be investigated. Thus,
the question of whether V-ISA modulates driving speed choice remains open. Here, we assessed the impact of V-ISA variants on driver speed choice. Thirty expert drivers experienced four simulated driving conditions, in
which the three V–ISA variants together with the V-ISA off control condition were tested separately. Furthermore, drivers were asked for feedback on the acceptance and usability of the three V-ISA. Our results suggested
that V–ISA was effective in mitigating the risks associated with speeding, with relatively high acceptance and perceived usability levels. The results indicate that V–ISA can have a positive impact on road safety by helping
drivers to modulate their chosen driving speed
Intelligent speed adaptation for visibility technology affects drivers’ speed selection along curves with sight limitations
Sight obstructions along road curves can lead to a crash if the driver is not able to stop the vehicle in time. This is a particular issue along curves with limited available sight, where speed management is necessary to avoid unsafe situations (e.g., driving off the road or invading the other traffic lane). To solve this issue, we proposed a novel intelligent speed adaptation (ISA) system for visibility, called V-ISA (intelligent speed adaptation for visibility). It estimates the real-time safe speed limits based on the prevailing sight conditions. V-ISA comes with three variants with specific feedback modalities (1) visual and (2) auditory information, and (3) direct intervention to assume control over the vehicle speed.Here, we investigated the efficiency of each of the three V-ISA variants on driving speed choice and lateral behavioural response along road curves with limited and unsafe available sight distances, using a driving simulator. We also considered curve road geometry (curve direction: rightward vs. leftward). Sixty active drivers were recruited for the study. While half of them (experimental group) tested the three V-ISA variants (and a V-ISA off condition), the other half always drove with the V-ISA off (validation group). We used a linear mixed-effect model to evaluate the influence of V-ISA on driver behaviour.All V-ISA variants were efficient at reducing speeds at entrance points, with no discernible negative impact on driver lateral behaviour. On rightward curves, the V-ISA intervening variant appeared to be the most effective at adapting to sight limitations. Results of the current study implies that V-ISA might assist drivers to adjust their operating speed as per prevailing sight conditions and, consequently, establishes safer driving conditions