The aim of the research was to develop the non-intrusive physiological measure of using human facial skin temperature change as an indicator of mental workload. The forehead and nose temperature were obtained via thermography from the participants who drove in a simulator driving environment and/or in instrumented car experiments. The NASA TLX and the Modified Cooper-Harper metrics were adopted to assess the subjective workload for the validation of the physiological measure. Three driving experiments were conducted in order to acquire the physiological response and the workload score for the performed tasks. Forehead temperature was very stable throughout the experiments. Nose temperature dropped significantly after the experimental drive for all conditions in simulator test. Experiment 1 (NASA TLX Group: N=10; MCH Group: N=14) used simulator driving with different terrains as loading tasks. Neither the significant difference of the subjective workload nor the temperature drop was detected between different terrain conditions. In experiment 2 (N=33), mental workload was increased in a controlled manner by the introduction of mental arithmetic tests to the primary simulated drive. The mental arithmetic test conditions provoked a significantly greater nose temperature drop and also a higher perceived workload than the conditions without the arithmetic test. A weak correlation between the nose temperature drop and the subjective workload metric was yielded from the experiments. In Experiment 3 (N=13), facial temperature response and subjective workload score were compared between the simulator test and on-road driving. Driving in the simulator resulted in higher subjective workload and greater nose temperature drop than in real-car driving. When participants perceived a higher workload for a task, their nose temperature exhibited a greater drop. A significant correlation between the nose temperature change and the subjective workload score was found. Actual or potential applications of this research include real-time and unobtrusive mental workload assessment for human-system interaction development.

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No description available.

The complexity and broadening of competencies have led to a number of assessment frameworks that advocate for the use of rater judgment in direct observation of clinical performance. The degree to which these assessment processes produce scores that are valid, are therefore vitally dependent on a rater’s cognitive ability. A number of theories suggest that many of the cognitive structures needed to complete rating tasks are capacity limited and may therefore become a source of difficulty when rating demands exceed resources. This thesis explores the role of rating demands on the performance and behaviour of raters in the assessment of clinical competence and asks: in what way do rating demands associated with rating clinical performance affect rater performance and behaviour? I hypothesized that as rating demands increase, rating performance declines and raters engage in cognitive avoidance strategies in order to complete the task. I tested this hypothesis by manipulating intrinsic and extraneous sources of load for raters in the assessment of clinical performance. Results consistently demonstrated that intrinsic load, specifically broadening raters’ focus by increasing the number of dimensions to be considered simultaneously, negatively affected indicators of rating quality. However, extraneous demands failed to result in the same effect in 2 of 3 experiments. When we explored the cognitive strategies raters engage under high load conditions we learned of a number of strategies to reduce cognitive work, including idiosyncratically minimizing intrinsic demands (leading to poor inter-rater reliability) and active elimination of sources of extraneous load, explaining both findings. When we induced extraneous load in manner that could not be easily minimized by raters, we also found impairments in rater performance, specifically the provision of feedback. I conclude that rating demands, whether induced intrinsically or by extraneous sources, impair rater performance affecting both the utility of scores and the opportunity for learner development. Implications for health professions education and future directions are discussed. / Dissertation / Doctor of Philosophy (PhD)

Workload is defined as the cost incurred by an individual, given their capacities, while achieving a particular level of performance on a task with specific demands. Demands of a task or combination of tasks may include maintaining postural stability, executing physical actions, and/or performing cognitive tasks. While there have been attempts to establish a physiological measure of concurrent physical and mental workload, as yet there has been no work towards developing a single subjective method of evaluation. Select subjective assessment methodologies were evaluated quantitatively during laboratory-based experiments. Concurrent execution of mental and physical activity was required at various levels, since it was desired to be able to measure mental workload, physical workload, and also evaluate their interaction. Measurements of task performance were investigated to evaluate the effects of combined mental and physical demands and establish which subjective assessments were accurate and sensitive to changes in workload. The utility of existing subjective assessment tools created for one domain appeared to be limited when evaluating multi-task situations requiring substantial mental and physical activity. Further clarification of the impact of different types of physical demand on cognitive processing, performance and subjective workload assessment of a constant mental task was addressed in the second experiment. This experiment investigated the effect of several activity types, specifically global versus localized effort, changes in load, and different task frequencies. The results provided support that the type of activity, load and frequency of task influence subjective mental workload assessment scores and performance. Not all existing assessment tools accurately represented an individual's ability to perform a task when there was a combination of physical and mental demands. A unidimensional tool is suggested as a screening tool to identify situations requiring excessive or increased mental workload. Alternative methods, possibly a new multidimensional tool, should be developed to obtain more detailed information so ratings of workload for different tasks may be compared. Effectiveness of a subjective stability assessment tool was evaluated in situations demanding mental activity while maintaining an upright posture. Tests were performed over a wide range of conditions, including various mental loads, sensory conditions, and postural stances. The purpose was to determine the effects of each task variation on the perception of postural stability. Postural sway increased with task difficulty, regardless of the source (i.e. postural stance, visual condition, mental workload). The addition of mental workload did not alter the non-linear relationship between objective measures of postural sway and perceptions of postural stability. Since decrements in balance are well perceived, subjective assessment tools may be incorporated in control strategies to minimize falls. / Ph. D.

As handheld computers are becoming powerful, portable and wireless, they have recently received considerable attention in education because their multi-functionality and mobility can be used for supporting learning activities in various manner. In spite of the potential in education, handheld computers have several limitations. One of the critical limitations is the small screen size. In an attempt to find factors affecting text readability on the small screen of handheld computers, this study, first, reviewed basic reading process and reading model, previous studies examining potential factors affecting text readability on a small handheld screen. This study investigated the effect of screen orientation and margin on reading performance (reading speed and comprehension) and subjective impressions (ease of reading, mental workload and satisfaction) with a handheld computer. A 2x2 within-subject factorial design was conducted with 16 participants reading texts from a PDA (Compaq iPAQ 3850). The results of this study indicated that neither screen orientation nor margin had a significant influence on objective reading performance and subjective impression. It was found that there were no prevailing preference of screen orientation and margin in reading texts from a handheld computer screen. It was also found that participants had a favorable reading experience with the handheld computers. Based on results of experiments and post-experiment questionnaire, a set of recommendations was developed to improve reading from small screens of handheld computers. / Master of Science

Forward operators are subjected to both physical and mental workload in their work and a way to reduce mental workload and increase productivity is to automating the crane movement. To enable study the impact of automation you need methods to estimate the forwarder operators mental workload in conventional crane work and with semi automation. This study evaluated the psychophysiological parameters; trapezius muscle activity, heart rate, heart rate variability, respiratory rate, skin conductance and finger temperature. To ensure the validity and methodology reliability one need to perform more extensive studies. As for future studies this work propose additional studies of forward operator mental workload in the simulator environment regarding heart rate, heart rate variability and respiration. / Skogsmaskinförarens arbete innebär en hög belastning såväl fysiskt som mentalt. Dels för att det innefattar moment av statiskt och repetitvt arbete och dels för att en stor mängd information bearbetas och många beslut fattas på kort tid. Mental belastning är ett begrepp för olika former av belastning som påverkar människans förmåga att bearbeta information. Det finns ingen enskild faktor som kan utgöra ett mått på mental belastning. Såväl prestation som subjektiva bedömningar och psykofysiologiska mätmetoder används för att mäta mental belastning. Exempel på psykofysiologiska mätmetoder är muskelaktivitet, hjärtfrekvens, hjärtfrekvensvariabilitet, andningsfrekvens, hudkonduktans och fingertemperatur. Ett sätt att försöka minska belastningen för skotarföraren är att automatisera vissa moment i kranens arbete. Syftet med examensarbetet var att utvärdera psykofysiologiska mätmetoder lämpliga för att beöma skillnaden i mental belastning hos skotarförare vid arbete med konventionellt- och delautomatiserat kranarbete i simulatormiljö. Resultatet visar på en potential hos analyserna hjärtfrekvens, hjärtfrekvensvariabilitet och andning för fortsatta studier. Muskelaktiviteten i form av trapezius-EMG och hudkonduktans var analyser behäftade med höga brusnivåer och artefakter i studien. Arbetet ger även en bild av komplexiteten i studier där teknik och människa interagerar. Den tekniska kapaciteten på skogsmaskiner är idag så avancerad att maskinföraren bedöms vara den begränsande faktorn för prestationen. För att öka produktiviteten i skogsbruket är det av stor vikt att den tekniska utvecklingen samspelar med interaktionen mellan människa och maskin för att främja ett hållbart skogsbruk för såväl maskinförare som för skog och miljö.

This diploma thesis deals with impact of stress on performance of military pilots of supersonic aircrafts. The theoretical part is based on definition of the term stress, his relating theories, the strategies of coping with stress and possible methods of objectivization of mental workload. This part also provides an overview of stress occuring during flight activity and specifics of the job of military pilot. The research is based on theoretical models and previous researches and the aim is to analyze the hypothesis about the dependence of stress on performance of the military pilot.This correlation was empirically verified by experimental study conducted in tactical flight simulator designed for a training on supersonic airplanes. The mental workload was investigated by physiological data and psychological questionnaires. The results are showing the most stressful and most difficult situations that appeared during tactical combat mission. There was a significant correlation between personality, resting heart rate and the effectivity of the performance. Key words: Stress, Military pilots, Performance, Mental workload, Heart rate

Background: Concern has been raised that the workload of community pharmacists (CPs) is linked to the occurrence of dispensing errors (DEs). One aspect of workload that has not yet been measured in this setting, but has been linked to errors in other industries, is mental workload (MWL). Aims: (1) Measure the relationship between MWL and DEs during a routine pharmacy task, the final accuracy check, which research suggests is critical to DE prevention. (2) Quantify the role that expertise plays in this relationship. (3) Explore CPs and pharmacy students’ experiences of MWL and DEs. Methods: A mixed methods approach was taken and three studies were conducted. In study one, CPs (n=104) and students (n=93) checked dispensed items for DEs. Participants took part in one of four conditions (distraction, no distraction, dual-task or single-task) and their DE detection and MWL was measured. Study two was a diary study of CPs’ (n=40) MWL during a day in their “real-life” practice. Study three presented an interpretative phenomenological analysis of CPs’ (n=14) and students’ (n=15) experiences of MWL and DEs. Main findings: Study one found that high MWL was related to reduced DE detection, but only for students, confirming the important role of expertise. Distractions did not affect DE detection but was linked to increased MWL. Study 2 highlighted specific times of the day when CPs’ MWL was exceptionally high. Study 3 found several factors which increased MWL, including the lack of control CP’s had over their workload, difficulties communicating with prescribers and targets. Conclusions: MWL has been found to be a useful tool for measuring the impact of workload on pharmacy safety. The findings are linked to current work design and human factors theory and suggestions are made for how CPs’ work could be redesigned to reduce their MWL and improve safety.

This research compares methods for measuring pilot mental workload (MWL) from the electrocardiogram (ECG) signal. ECG-based metrics have been used extensively in MWL research. Heart rate (HR) and heart-rate variability (HRV) exhibit changes in response to varying levels of task demand. Classical methods for HRV analysis examine the ECG signal in the linear time and frequency domains. More contemporary research has advanced the notion that nonlinear elements contribute to cardiac control and ECG signal generation, spawning development of analytical techniques borrowed from the domain of nonlinear dynamics (NLD). Applications of nonlinear HRV analysis are substantial in clinical diagnosis settings; however, such applications are less frequent in MWL research, especially in the aviation domain. Specifically, the relative utility of linear and non-linear HRV analysis methods has not been fully assessed in pilot MWL research. This thesis contributes to aforementioned research gap by comparing a non-linear HRV method, utilizing transition probability variances (TPV), to classical time and frequency domain methods, focusing the analysis on sensitivity and diagnosticity. ECG data is harvested from a recent study characterizing spatial disorientation (SDO) risk amongst three candidate off-boresight (OBS) helmet-mounted display (HMD) symbologies in a tactically relevant live-flight task. A comparative analysis of methods on this dataset and supplemental workload analysis for the HMD study are presented. Results indicate the TPV method may exhibit higher sensitivity and diagnosticity than classical methods. However, limitations of this analysis warrant further investigation into this question.