The Effects of Work Zone Configurations on Physiological and Subjective Workload

There is a dearth of research on the effect of driving through work zones on physiological and subjective workload of drivers. The objectives of this research were to (a) study the effect of work zones and traffic density on physiological measures of workload, subjective workload and performance variables (b) study the relationship between physiological measures of workload, subjective workload and performance variables. Conventional lane merge (CLM), joint lane merge (JLM) and a road without a work zone (control) were modeled with high and low traffic density by using a full-size driving simulator. 13 female and 17 male students volunteered to participate in this study. Data regarding physiological measures of workload through heart rate variability measures (RMSSD, LF, HF and LF/HF ratio) were collected by using a heart monitoring watch. NASA-TLX was used to measure subjective workload. Variability in steering, braking and speed were used as performance variables. Results showed that the driving scenarios and traffic density did not affect physiological measures of workload. In terms of subjective workload, CLM and JLM did not differ significantly from each other. However, with respect to mental demand, temporal demand, effort and total workload, CLM was significantly more demanding than the control group. Total workload for driving in high traffic density was 27.2% more than that of in low traffic density. No significant differences were observed in brake variability between different scenarios. However, CLM and JLM had significantly higher speed variability than the control group but they were not significantly different from each other. Steer variability and brake variability were higher in high traffic density. In conclusion, results showed that when it comes to using driving simulators, physiological measures of workload show no sensitivity to changes in the work zone but subjective and performance variables are influenced and can be used to compare different work zone configurations

Improving passive driver fatigue, sitting health risk factors and user experience in automobiles. Conception, development and evaluation of a novel interactive seating system

Lange Fahrten in Automobilen werden oftmals von monotoniebedingter Ermüdung durch mangelnde Stimulation sowie körperlichen Gesundheitsrisiken durch langanhaltendes Sitzen begleitet. In der Literatur werden kognitive Zusatzaufgaben als Maßnahme gegen monotoniebedingte Ermüdung vorgeschlagen. Der Stand der Technik um gesundheitliche Risiken durch langanhaltendes Sitzen im Fahrzeug zu reduzieren, beschränkt sich hauptsächlich auf Sitzsysteme, welche die Passagiere passiv mobilisieren. Mit dem Ziel die Fahrsicherheit zu erhöhen und gleichzeitig Gesundheitsrisiken zu reduzieren, wurde ein neuartiges interaktives Sitzsystem (IASS) konzipiert, entwickelt und evaluiert. Das IASS soll den Fahrer/die Fahrerin oder die Passagiere dazu motivieren mit dem Sitz zu interagieren und dabei aktive Bewegungen gegen die Sitzfläche auszuführen. Im Gegensatz zu aktuellen interaktiven Sitzsystemen erfolgt die grundlegende Interaktion nicht über ein Display. Stattdessen werden auditive Einsprachen, Luftblasen in der Lehne, Vibrationsmotoren sowie die Ambientebeleuchtung genutzt. Ein Display kommt lediglich bei der Einführung in die Nutzung des Systems oder ergänzend für die Passagiere zum Einsatz. Das ermöglicht, dass der Fahrer/die Fahrerin den Blick und damit auch die Aufmerksamkeit auf der Straße behalten kann. Dadurch soll das System, im Gegensatz zum Stand der Technik, nicht nur für die Passagiere, sondern auch für den Fahrer/die Fahrerin geeignet sein. Das wiederum eröffnet die Möglichkeit das IASS als Zusatzaufgabe neben dem Fahren zu nutzen, um einer momotoniebedingten Reduktion der Aufmerksamkeit entgegenzuwirken. Dabei ist anzumerken, dass die erhöhte Fahrsicherheit durch eine verbesserte Aufmerksamkeit nicht nur den Insassen, sondern auch den anderen Verkehrsteilnehmern dient. Gleichzeitig haben alle Passagiere die Möglichkeit, durch die physiologisch sinnvollen Bewegungen gegen den Sitz, die Gesundheitsrisiken durch langanhaltendes Sitzen zu reduzieren. Insgesamt wurden drei Probandenstudien durchgeführt, um das IASS zu entwickeln und zu evaluieren. Die erste Probandenstudie diente der Entwicklung des IASS. Um die Bewegungen des Passagiers/der Passagierin bei der Interaktion zu detektieren, wurden Drucksensoren in der Sitzlehne integriert. Zur Gewährleistung einer zuverlässigen Bewegungserkennung von Passagieren mit unterschiedlichen anthropometrischen Merkmalen, war es entscheidend, die Sensoren an optimalen Positionen in der Lehne zu platzieren. Daher war der erste Schritt im Entwicklungsprozess des IASS die Durchführung einer Probandenstudie, um diese optimalen Positionen festzulegen. Im Rahmen der Studie wurden Sitzdruckverteilungsbilder erfasst und anschließend mit einer Methode, dem Statistical Parametric Mapping ausgewertet, die für gewöhnlich bei der funktionellen Magnetresonanztomographie eingesetzt wird. In der vorliegenden Arbeit wurde diese Methode erstmalig zur Auswertung von Sitzdruckverteilungen herangezogen. Der Vorteil gegenüber herkömmlichen Methoden ist die hohe örtliche Auflösung. Damit war es möglich, die Sensoranbringungspunkte sehr präzise zu definieren. Anschließend wurde das IASS auf Basis der in der ersten Studie gewonnenen Information aufgebaut und anschließend in zwei weiteren Probandenstudien mit einem aktuellen Sitzmassagesystem (MS) hinsichtlich Wirksamkeit verglichen. In der zweiten Probandestudie sollte das Potential des IASS für die Fahrsicherheit bewertet werden. Die im Fahrsimulator durchgeführte Studie zeigte, dass das IASS die monotoniebedingte Ermüdung reduzierte, während dieser Effekt bei Nutzung des MS nicht auftrat. Das IASS wurde ebenfalls bezüglich des Nutzererlebnisses sowie der emotionalen Wahrnehmung gegenüber dem MS bevorzugt. Außerdem bewerteten die Probanden und Probandinnen, dass das IASS im Vergleich zum MS, sowohl Komfort wesentlich stärker erhöhte als auch Diskomfort stärker reduzierte. In der dritten und abschließenden Probandenstudie wurde untersucht, ob das IASS den körperlichen Gesundheitsrisiken durch langanhaltendes Sitzen besser entgegen wirkt als das MS. Hierfür wurden beide Sitzsysteme in einem Serienfahrzeug verbaut. Um die Effekte beider Sitzsysteme zu vergleichen, wurden gesundheitsrelevante Parameter erfasst. Damit fahrtbedingte Signalstörungen ausgeschlossen werden konnten, wurde die Studie im stehenden Fahrzeug durchgeführt. Das Elektrokardiogramm zeigte, dass ausschließlich das IASS die Herzfrequenz erhöhte. Elektromyographische Messungen zeigten außerdem, dass das IASS die Aktivität in den sechs erfassten Muskeln erhöhte, während beim MS lediglich ein Muskel eine Tendenz zur Aktivitätserhöhung zeigte. Entsprechend sind die gesundheitsfördernden Effekte des IASS im Vergleich zum MS als wesentlich stärker einzustufen. Nach dem Kenntnisstand des Autors, ist dies die erste wissenschaftliche Publikation welche eine motorische Zusatzaufgabe als Maßnahme gegen monotoniebedingte Ermüdung im Fahrzeug untersucht. Darüber hinaus wurde erstmalig direkt verglichen, ob ein automobiles Sitzsystem welches zu aktiven Bewegungen animiert, einem System das die Passagiere passiv bewegt, hinsichtlich der Reduktion der negativen körperlichen Effekte des Sitzens überlegen ist

Deciphering Psychological-Physiological Mappings While Driving and Performing a Secondary Memory Task

An autonomic space model of sympathetic and parasympathetic influences on the heart has been proposed as a method of deciphering psychological-physiological mappings for driving-related tasks. In the current study, we explore the utility of the autonomic space model for deciphering mappings in a driving simulation environment by comparing a single-task driving-only condition to two dual-task, driving-with-a-secondary-workingmemory task conditions. Although limited by a small sample size, the results illustrate the advantages physiological measures can have over performance measures for detecting changes in the psychological process required for drivingrelated task performance. Future research will include a repetition of this same study with more subjects as well the collection of on-the-road autonomic nervous system data

Inconsistencies between mental fatigue measures under compensatory control theories

Mental fatigue has traditionally been defined as a condition of reduced cognitive efficiency and performance, accompanied by a subjective feeling of fatigue. Even though we could expect to find associations between the three defining characteristic of mental fatigue (performance impairment, physiological deactivation and subjective fatigue), research has shown that the emergence of inconsistencies between measures is more frequent than one might expect: people proved capable of maintaining adequate performance levels even after having declared themselves fatigued. This could be explained under the compensatory control mechanism models, which state that humans are able to provide additional resources under demanding conditions, but only at the expense of psychophysiological cost and subjective fatigue. We tested this explanation by manipulating task complexity and time performing a simulated air-traffic control task. We collected psychophysiological, performance and subjective data. A decrease in pupil size was seen in the low-aircraft-density condition, while pupil size remained constant in the high-aircraft-density condition. Participants’ task performance was optimal in both conditions, though they showed an increase in subjective feelings of fatigue, especially in the high-complexity task condition. Thus, complexity seemed to trigger compensatory mechanisms, which reallocated extra resources that physiologically activated participants in order to deal with a higher complexity task, whereas subjective fatigue could be acting as a signal to the organism of impending resource depletion. Our findings support compensatory control theories and offer an explanation of inconsistencies between fatigue measures. Further research on compensatory mechanisms is needed to enable better management of fatigue effects to prevent work-related accidents.Spanish Ministry of Industry PI-1461/201

Exploring the effect of simulated Motion Conditions on Task Performance

This thesis explored the effect that four different areas of motion conditioning presented in a motion simulator had on defence-force based task performance. It is produced in conjunction with the Defence Science and Technology Organisation, Land Operations Division, to expand their understanding of how these conditions may affect their personnel. The four conditions are explored are Motion Sickness, Motion Fatigue, Motion Perception and Mental Workload under motion conditions. All studies involved first year psychology students enrolled at the University of Sydney in accordance with the University’s ethical guidelines (2013/388). In the study of Motion Sickness, nausea was shown to have very little detrimental effect on task performance. In long term driving exposure there was a slight negative effect on the reaction time that was linked to motion sickness symptoms. Two styles of driving were researched for Motion Fatigue: boredom and constant motion. The boredom drive was seen to have a slightly negative effect on performance compared to the motion drive. In analysing biomarkers of fatigue relevant to a defence context, the best indicators were respiratory rate and the Root Mean Square of Successive Differences between normal heart beats. In Motion Perception, 6-axes of motion at 3 intensities were tested using Defence force tasks to determine whether any one axis, or a certain intensity, negatively affected performance more than others. Higher errors occurred in the Roll direction. The Pitch direction was the least comfortable for participants. In the final chapter of Mental Workload under motion, increased workload did not have a great impact on performance, although further studies are needed. In an analysis of subjective scales of workload in simple tasks, participants were able to accurately determine their task performance. From a bio-measure perspective, pupil diameter and respiratory rate were found to be the most indicative of changing levels of workload

Exploring the effect of simulated Motion Conditions on Task Performance

This thesis explored the effect that four different areas of motion conditioning presented in a motion simulator had on defence-force based task performance. It is produced in conjunction with the Defence Science and Technology Organisation, Land Operations Division, to expand their understanding of how these conditions may affect their personnel. The four conditions are explored are Motion Sickness, Motion Fatigue, Motion Perception and Mental Workload under motion conditions. All studies involved first year psychology students enrolled at the University of Sydney in accordance with the University’s ethical guidelines (2013/388). In the study of Motion Sickness, nausea was shown to have very little detrimental effect on task performance. In long term driving exposure there was a slight negative effect on the reaction time that was linked to motion sickness symptoms. Two styles of driving were researched for Motion Fatigue: boredom and constant motion. The boredom drive was seen to have a slightly negative effect on performance compared to the motion drive. In analysing biomarkers of fatigue relevant to a defence context, the best indicators were respiratory rate and the Root Mean Square of Successive Differences between normal heart beats. In Motion Perception, 6-axes of motion at 3 intensities were tested using Defence force tasks to determine whether any one axis, or a certain intensity, negatively affected performance more than others. Higher errors occurred in the Roll direction. The Pitch direction was the least comfortable for participants. In the final chapter of Mental Workload under motion, increased workload did not have a great impact on performance, although further studies are needed. In an analysis of subjective scales of workload in simple tasks, participants were able to accurately determine their task performance. From a bio-measure perspective, pupil diameter and respiratory rate were found to be the most indicative of changing levels of workload

Quantifying cognitive workload and defining training time requirements using thermography

Effective mental workload measurement is critical because mental workload significantly affects human performance. A non-invasive and objective workload measurement tool is needed to overcome limitations of current mental workload measures. Further, training/learning increases mental workload during skill or knowledge acquisition, followed by a decreased mental workload, though sufficient training times are unknown. The objectives of this study were to: (1) investigate the efficacy of using thermography as a non-contact physiological measure to quantify mental workload, (2) quantify and describe the relationship between mental workload and learning/training, and, (3) introduce a method to determine a sufficient training time and an optimal human performance level for a novel task by using thermography. Three studies were conducted to address these objectives. The first study investigated the efficacy of using thermography to quantity the relationship between mental workload and facial temperature changes while learning an alpha-numeric task. Thermography measured and quantified the mental workload level successfully. Strong and significant correlations were found among thermography, performance, and subjective workload measures (MCH and SWAT ratings). The second study investigated the utility of using a psychophysical approach to determine workload levels that maximize performance on a cognitive task. The second study consisted of an adjustment session (participants adjusted their own workload levels) and work session (participants worked at the chosen workload level). Participants were found to fall into two performance groups (low and high performers by accuracy rate) and results were significantly different. Thermography demonstrated whether both group found their optimal workload level. The last study investigated efficacy of using thermography to quantify mental workload level in a complex training/learning environment. Experienced drivers’ performance data was used as criteria to indicate whether novice drivers mastered the driving skills. Strong and significant correlations were found among thermography, subjective workload measures, and performance measures in novice drivers. This study verified that thermography is a reliable and valid way to measure workload as a non-invasive and objective method. Also, thermography provided more practical results than subjective workload measures for simple and complex cognitive tasks. Thermography showed the capability to identify a sufficient training time for simple or complex cognitive tasks

A Quantitative analysis of the mental workload demands of MRAP vehicle drivers using physiological, subjective, and performance assessments

United States Special Operations Command (USSOCOM) Operators and vehicle Commanders are specially trained United States military Warfighters that have the demanding task of operating or working onboard Mine Resistant Ambush Protected (MRAP) All Terrain Vehicles (M-ATVs). Their missions encounter significant mental demands resulting from fatigue, highly stressful situations, and interactions with Government Furnished Equipment (GFE). Excessive mental demands can be the primary factor leading to compromised vehicle communication, missed improvised explosive device (IED) detection, and increased incidents of vehicle roll-over. Research has demonstrated the consequences of mental overloading including increased errors, performance decrements, distraction, cognitive tunneling and inadequate time to appropriately process information. The objectives of this thesis were to evaluate the extent to which task-related factors impact the mental workload of Warfighters and to evaluate the consistency among the three categories of mental workload metrics. The 14 participants studied in this research were Marine Corps personnel who had heavy vehicle driving experience. Physiological, subjective and performance measures were collected during a four-segment course that progressed in difficulty and analyzed across all participants to assess changes in mental workload. It was found that task-related factors impacted the mental workload of Warfighters. The subjective metric was able to capture changes in workload more accurately than biosignals. Due to technical problems with the biosignal data, comparison of consistency across metrics was inconclusive. The subjective workload ratings were significantly different between course segments and experience levels. The experiment resulted in workload ratings that increased by as much as 94% between segments and were 18% higher among novice drivers. This study showed that mental workload fluctuates while driving in a stressful situation, despite training and experience, and consequently, detection performance will be impacted which could have very adverse consequences. There is the need for additional research to have a better understanding of the true impact of mental workload on MRAP vehicle drivers, especially in an operational environment

EEG-based mental workload neurometric to evaluate the impact of different traffic and road conditions in real driving settings

Car driving is considered a very complex activity, consisting of different concomitant tasks and subtasks, thus it is crucial to understand the impact of different factors, such as road complexity, traffic, dashboard devices, and external events on the driver’s behavior and performance. For this reason, in particular situations the cognitive demand experienced by the driver could be very high, inducing an excessive experienced mental workload and consequently an increasing of error commission probability. In this regard, it has been demonstrated that human error is the main cause of the 57% of road accidents and a contributing factor in most of them. In this study, 20 young subjects have been involved in a real driving experiment, performed under different traffic conditions (rush hour and not) and along different road types (main and secondary streets). Moreover, during the driving tasks different specific events, in particular a pedestrian crossing the road and a car entering the traffic flow just ahead of the experimental subject, have been acted. A Workload Index based on the Electroencephalographic (EEG), i.e., brain activity, of the drivers has been employed to investigate the impact of the different factors on the driver’s workload. Eye-Tracking (ET) technology and subjective measures have also been employed in order to have a comprehensive overview of the driver’s perceived workload and to investigate the different insights obtainable from the employed methodologies. The employment of such EEG-based Workload index confirmed the significant impact of both traffic and road types on the drivers’ behavior (increasing their workload), with the advantage of being under real settings. Also, it allowed to highlight the increased workload related to external events while driving, in particular with a significant effect during those situations when the traffic was low. Finally, the comparison between methodologies revealed the higher sensitivity of neurophysiological measures with respect to ET and subjective ones. In conclusion, such an EEG-based Workload index would allow to assess objectively the mental workload experienced by the driver, standing out as a powerful tool for research aimed to investigate drivers’ behavior and providing additional and complementary insights with respect to traditional methodologies employed within road safety research