Numerous aspects of job scheduling in manufacturing systems have been the focus of several studies in the past decades. However, human factors in manufacturing systems such as workers’ mental conditions are still neglected issues and have not received adequate attentions. Job boredom and mental fatigue are both aspects of workers’ mental condition. They affect work performances by increasing sick leave duration and decreasing work productivity. On the other hand, job rotation could be an alternative strategy to cope with such human issues at work. The benefits of job rotation for both employees and firms have been widely recognized in the literature. Although some studies found job rotation as a means to reduce workers' physical work-related traumas, they did not consider the effect of variable mental conditions on workers. Despite the proven importance of boredom and mental fatigue at the workplace, they have not been a combined precise objective of any job rotation problem in current literature. The study of mental conditions proposed in this paper attempts to extend the previous works by addressing new methods and developing a feasible solution to increase manufacturing productivity. A new job scheduling program has been designed specifically which combines a new job rotation model and a job assignment method.

Introduktion: Tidigare forskning tyder på att hjärntrötthet är ett komplext tillstånd som negativt påverkar individens livssituation och kan skapa obalans i vardagliga aktiviteter. Syfte: Att beskriva arbetsterapeuters erfarenheter av interventioner för individer med hjärntrötthet. Metod: En kvalitativ design valdes för att besvara studiens syfte. Avsiktligt urval användes för att utse tio arbetsterapeuter med erfarenhet inom området. Data samlades in med hjälp av semistrukturerade intervjuer med öppna intervjufrågor. Innehållsanalys genomfördes på de transkriberade intervjuerna, vilket resulterade i ett tema, tre kategorier samt sju underkategorier. Resultat: Resultatet sammanfattades i temat ”Arbetsterapeuten som coach med individen i fokus”. Kategorierna som framkom var; Information och rådgivning: vikten av att informera patienter och anhöriga om innebörden av hjärntrötthet samt nyttan med interaktion där arbetsterapeuten agerade coach och patienten gavs möjlighet att reflektera. Strategier: genom exempelvis identifiering, planering och struktur av aktivitetsmönster erbjöds patienten hantering av hjärntröttheten och kunde därmed bättre klara sin vardag. Hjälpmedel: individanpassade hjälpmedel av olika slag kunde underlätta i patientens vardag. Slutsatser: Det fanns inte några färdiga interventioner för patienter med hjärntrötthet utan åtgärderna behövde anpassas för varje specifik individ. Genom coachning, strategier och hjälpmedel kunde patienterna lära sig att hantera sin hjärntrötthet och få vardagen att fungera. / Introduction: Previous researches indicate that mental fatigue is a complex condition that adversely affects the individual's life situation and can cause imbalance in everyday activities. Aim: To describe occupational therapists' experiences of interventions for individuals with mental fatigue. Method: A qualitative design was chosen to answer the purpose of this study. Target selection was used to elect ten occupational therapists with experience in the field. Data was collected using semi-structured interviews with open interview questions. Content analysis was conducted on the transcribed interviews, resulting in one theme, three categories and seven subcategories. Result: The result was summarized in a theme: Occupational therapist as a coach with focus on the individual. The categories were; Information and counseling: the importance of informing patients and relatives about mental fatigue as well as the benefit of interaction. Strategies: further interventions were enabled through patients identifying and acquiring insight of his or her own situation. Assistive devices: individualized assistive devices could support the patient's everyday life. Conclusions: Results showed that there were no ready-made interventions for patients with mental fatigue and that the interventions had to be individualized for each specific individual. The purpose of the interventions was to teach patients to deal with their mental fatigue and

This work describes basics of electroencephalography, measuring methods of electroen- cephalographic signals, their processing and especially the interpretation of EEG signal in frequency and time-frequency domains for mental fatigue detection purposes. Mental fatigue, its sources, consequences and connection with sensory-cognitive system and link to memory is discussed. The most basic normalized international system for measuring EEG from the scalp as well as some of the experiments that ultimately lead to mental fatigue are described. With this knowledge in mind, an experiment was prepared for inducing such a state. Ten subjects participated in the test which was conducted in la- boratory with EEG machine GES 410MR by EGI. The data were analyzed mainly with S-transform and Hilbert-Huang transform. These two transforms represent two distinct state of the art time-frequency methods of spectral analysis. The result of this work lies in evaluating the relationship between mental fatigue, errors accumulated during the task and with time.

Im Rahmen dieser Arbeit wird untersucht, wie Daten der Eye-Tracking Brille Pupil Invisible genutzt werden können, um mit Methoden der Mustererkennung Mentoring-Anlässe zu erkennen. Die Arbeit ist Teil der Erforschung eines virtuellen Mentoring-Systems, welches Studierende bei der Bearbeitung von Online-Learnaufgaben auf der Lernplattform OPAL unterstützt. Als Mentoring-Anlass wird in erster Linie die Erkennung von mentaler Ermüdung untersucht, wobei Methoden der Psychologie zur Erkennung und Induktion ebendieser genutzt werden. Dabei werden im Rahmen einer Vorstudie Eye-Tracking Daten gesammelt, die anschließend von den Mustererkennungsalgorithmen Stützvektormaschine, Random Forest und künstlichem neuronalen Netz ausgewertet werden. Die Ergebnisse zeigen, dass die Erkennung von mentaler Ermüdung anhand der verwendeten Methodiken möglich ist. Zusätzlich wird ein Toolkit entwickelt, um die beschriebenen Prozesse zu automatisieren und die Einbindung in ein virtuelles Mentoring-System zu vereinfachen.:Kurzfassung, Abstract Selbständigkeitserklärung Vorwort Abkürzungsverzeichnis 1 Einführung 1.1 Motivation 1.2 Zielsetzung 2 Theoretische Grundlagen 2.1 Grundlagen des Eye-Trackings 2.1.1 Grundbegriffe und Charakteristiken des Eye-Trackings 2.1.2 Arten des Eye-Trackings 2.1.3 Wichtige Algorithmen 2.2 Grundlagen der Mustererkennung 2.2.1 Vorverarbeitung 2.2.2 Merkmalsextraktion und Auswahl 2.2.3 Klassifikation und Beurteilung 2.3 Grundlagen zu mentaler Ermüdung 2.3.1 Definition 2.3.2 Abgrenzung 3 Stand der Forschung 3.1 Pupil Invisible 3.2 Erkennung von mentaler Ermüdung 3.3 Einordnung 4 Methodik und Implementierung 4.1 Vorstudie 4.1.1 Sitzungsskript 4.1.2 Einarbeitung 4.2 Datenvorverarbeitung 4.2.1 Pistol-Framework 4.2.2 Verarbeitung der Rohdaten 4.2.3 Problemspezifische Merkmalserzeugung 4.3 Klassifikationsalgorithmen 4.3.1 Optimierung 4.3.2 Klassifikation mit künstlichen neuronalen Netzen 4.3.3 Auswertung 4.4 Toolkit 5 Ergebnisse 5.1 Vorstudie 5.2 Auswahl der Merkmale 5.3 Klassifikation 6 Diskussion 7 Zusammenfassung und Ausblick 7.1 Zusammenfassung 7.2 Ausblick Abbildungsverzeichnis Tabellenverzeichnis Literaturverzeichnis Anhang A.1 Tabellen A.1.1 Pearson und Spearman Korrelationstests (vollständig) A.2 Sitzungsskript A.2.1 Ablauf A.2.2 Durchzuführende Aufgaben / This thesis investigates how data from the eye-tracking glasses Pupil Invisible can be used to detect mentoring occasions using pattern recognition methods. The work is part of the research of a virtual mentoring system that supports students in completing online learning tasks on the OPAL learning platform. As a mentoring occasion, the detection of mental fatigue is primarily investigated, using methods from psychology for the detection and induction of just that. In this regard, eye-tracking data is collected as part of a preliminary study, which is then evaluated by the support vector machine, random forest and artificial neural network pattern recognition algorithms. The results show that the detection of mental fatigue is possible based on the methodologies used. In addition, a toolkit is developed to automate the described processes to facilitate their incorporation into a virtual mentoring system.:Kurzfassung, Abstract Selbständigkeitserklärung Vorwort Abkürzungsverzeichnis 1 Einführung 1.1 Motivation 1.2 Zielsetzung 2 Theoretische Grundlagen 2.1 Grundlagen des Eye-Trackings 2.1.1 Grundbegriffe und Charakteristiken des Eye-Trackings 2.1.2 Arten des Eye-Trackings 2.1.3 Wichtige Algorithmen 2.2 Grundlagen der Mustererkennung 2.2.1 Vorverarbeitung 2.2.2 Merkmalsextraktion und Auswahl 2.2.3 Klassifikation und Beurteilung 2.3 Grundlagen zu mentaler Ermüdung 2.3.1 Definition 2.3.2 Abgrenzung 3 Stand der Forschung 3.1 Pupil Invisible 3.2 Erkennung von mentaler Ermüdung 3.3 Einordnung 4 Methodik und Implementierung 4.1 Vorstudie 4.1.1 Sitzungsskript 4.1.2 Einarbeitung 4.2 Datenvorverarbeitung 4.2.1 Pistol-Framework 4.2.2 Verarbeitung der Rohdaten 4.2.3 Problemspezifische Merkmalserzeugung 4.3 Klassifikationsalgorithmen 4.3.1 Optimierung 4.3.2 Klassifikation mit künstlichen neuronalen Netzen 4.3.3 Auswertung 4.4 Toolkit 5 Ergebnisse 5.1 Vorstudie 5.2 Auswahl der Merkmale 5.3 Klassifikation 6 Diskussion 7 Zusammenfassung und Ausblick 7.1 Zusammenfassung 7.2 Ausblick Abbildungsverzeichnis Tabellenverzeichnis Literaturverzeichnis Anhang A.1 Tabellen A.1.1 Pearson und Spearman Korrelationstests (vollständig) A.2 Sitzungsskript A.2.1 Ablauf A.2.2 Durchzuführende Aufgaben

Assessing the pilot’s cognitive state is of increasing importance in aviation, especially for the development of adaptive assistance systems. For this purpose, the assessment of mental workload (MWL) is of special interest as an indication when and how to adapt the automation to fit the pilot’s current needs. Thus, there is a need to assess the pilot continuously, objectively and non-intrusively. Neurophysiological measurements like electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) are promising candidates for such an assessment. Yet, there is evidence that EEG- and fNIRS-based MWL measures are susceptible to influences from other concepts like mental fatigue (MF), and decrease in accuracy when MWL and MF confound. Still, there are only few studies targeting this problem, and no systematic investigation into this problem has taken place. Thus, the validity of neurophysiological MWL measures is not clear yet. In order to undertake such a systematic investigation, I conducted three studies: one experiment in which I investigated the effects of increasing MWL on cortical activation when MF is controlled for; a second experiment in which I examined the effects of increasing MF on cortical activation when MWL is controlled for; and a further comparative analysis of the gathered data. In order to induce MWL and MF in a controllable and comparable fashion, I conceived and used a simplified simulated flight task with an incorporated adapted n-back and monitoring task. I used a concurrent EEG-fNIRS measurement to gain neurophysiological data, and collected performance data and self-reported MWL and MF. In the first study (N = 35), I induce different four levels of MWL by increasing the difficulty of the n-back task, and controlled for MF by means of randomization and a short task duration (≤ 45 minutes). Higher task difficulty elicited higher subjective MWL ratings, declining performance, increased frontal theta band power and decreased frontal deoxyhaemoglobin (HbR) concentration. Furthermore, fNIRS proved more sensitive to tasks with low difficulty, and EEG to tasks with high difficulty. Only the combination of both methods was able to discriminate all four induced MWL levels. Thus, frontal theta band power and HbR were sensitive to changing MWL. In the second study (N = 31), I. I induced MF by means of time on task. Thus, I prolonged the task duration to approx. 90 minutes, and controlled for MWL by using a low but constant task difficulty derived from the first experiment. Over the course of the experiment, the participants’ subjective MF increased linearly, but their performance remained stable. In the EEG data, there was an early increase and levelling in parietal alpha band power and a slower, but steady increase in frontal theta band power. The fNIRS data did not show a consistent trend in any direction with increasing MF. Thus, only parietal alpha and frontal theta band power were sensitive to changing MF. In the third study, I investigated the validity of two EEG indices commonly used for MWL assessment, the Task Load Index (TLI) and the Engagement Index (EI). I computed the indices from the data of the two experiments, and compared the results between the datasets, and to single band powers. The TLI increased with increasing MWL, but was less sensitive than theta band power alone, and varied slightly with increasing MF. The EI did not vary with MWL, and was not sensitive to gradually increasing MF. Thus, neither index could be considered a valid MWL measure. In sum, neurophysiological measures can be used to assess changes in MWL. Yet, frontal HbR was the only measure sensitive to MWL that did not also vary with MF, and further research is needed to conclude if this finding holds true under different task characteristics. Thus, the tested EEG and fNIRS measures are only valid indications of MWL when confounding effects of MF are explicitly controlled for. I discuss further influences on the tested EEG and fNIRS measures, possible combinations with other data sources, and practical challenges for a neurophysiological MWL assessment. I conclude that neurophysiological measures should be used carefully outside the laboratory, as their validity will likely suffer in realistic settings. When their limitations are understood and respected, they can help to understand the cognitive processes involved in MWL, and can be a valuable addition to an MWL assessment.

Self-control exertion leads to performance decrements during tasks demanding of muscular and cardiovascular systems (Bray et al., 2008; Marcora et al., 2009). Several reviews have also implicated self-control depletion with the psychobiological state of fatigue (Hagger et al., 2010; Van Cutsem et al., 2017). In this state, individuals have also been noted to report higher levels of perceived exertion when exercising at vigorous intensities (MacMahon et al., 2014; Marcora et al., 2009; Wagstaff et al., 2014). The purpose of this study was to investigate physical performance and ratings of perceived exertion during a self-paced maximum distance cycling trial (MDT) following a short bout of mentally-fatiguing cognitive activity (thought-suppression). Recreationally active participants (N = 16, Mage = 20.94) completed one familiarization session and two testing sessions. All visits were separated by ≥ 72-hours. Control and experimental trials were counterbalanced, with either a 6-minute bout of thought-logging (control) or a 6-minute bout of thought-suppression (experimental) being performed prior to each respective MDT. Ratings of perceived exertion (RPE) were solicited from participants across three sensory domains relevant to MDT task performance (Leg-muscle, Respiration, Mental). Thought-suppression was perceived to be significantly more demanding than the control task, which resulted in significantly higher ratings of mental fatigue (p = 0.04, 2 = 0.26). Distance travelled on the MDT was not significantly different following thought suppression, relative to control trials (p = 0.84, 2 = 0.00). Similarly, a repeated-measures ANOVA showed no differences in HR between conditions (p = 0.95, 2 = 0.00). Despite these similarities, ratings of perceived leg-muscle exertion (RPE-L) were significantly higher during the MDT following thought-suppression (p = 0.05, 2 = 0.24). RPE-R (respiration) and RPE-M (mental) ratings also trended towards higher scores following the experimental manipulation, although they did not differ significantly. RPE-L was perceived to be significantly higher than both RPE-R and RPE-M in both conditions on the MDT (ps < 0.05). RPE-M was rated significantly lower than RPE-L and RPE-R during MDTs in both conditions (ps < 0.05). Results indicate that performing a demanding self-control exertion task for a short duration leads to increased feelings of mental fatigue. The observed levels of fatigue were also associated with higher than normal ratings of perceived exertion during cycling tasks of equal demands and performance. / Thesis / Master of Science (MSc) / Any thought, emotion or behaviour that an individual modifies in order to better suit their goals occurs as a result of self-control exertion. Research indicates that just like the exertion of muscular strength, exerting self-control impacts subsequent attempts to do so. Using a mentally-demanding task, we induced states of self-control depletion which left individuals feeling mentally-fatigued. As a result of this state, participants needed to exert themselves harder in order to complete a task that was perceived less demanding, when non-fatigued.

People’s decisions regarding effort-based tasks such as engaging in physical activity depend on the subjective value of the activity: weighing the costs against the benefits (Chong et al., 2016). Exerting cognitive effort while performing one task negatively biases people's decisions to exert effort on subsequent cognitive tasks, suggesting a shift in their subjective valuation of the task due to mental fatigue (Kool & Botvinick, 2014). Similarly, exerting physical effort negatively biases decisions to further exert effort on a future physical task (Iodice et al., 2017a, Iodice et al., 2017b). The purpose of the present study was to investigate the effect of mental fatigue on people's decisions to engage in an acute bout of exercise and whether the effect of mental fatigue on decision-making was mediated by a benefit-cost analysis. Among those who decided to exercise, the study also aimed to investigate the relationship between mental fatigue and exercise behaviours during a self-selected, self-paced, bout of exercise. Recreationally active participants (N = 55, Mage = 19.04 ± 1.04 years) completed either a 10-minute, high cognitive demand (Stroop) task or low cognitive demand (documentary viewing) task to manipulate levels of mental fatigue. Participants then made a choice between engaging in a 20-minute self-paced moderate-to-vigorous intensity exercise task or a 20-minute non-exercise task. Prior to choosing, participants rated their mental fatigue and their perceived benefits and costs of the exercise task. The cognitive task had a strong effect on mental fatigue (p < .001, Cohen's d = 1.40). The mediation analysis showed no direct effect of mental fatigue on choice; however, there was a significant indirect effect indicating the benefit-cost score mediated the effect of mental fatigue on choice (95% C.I. = -.02 to -.0004). Higher levels of mental fatigue were associated with a lower benefit-cost score (r = -.33, p = .01) which, in turn, was associated with a decreased likelihood of choosing the exercise task (r = .31, p = .02). For those who chose to engage in the exercise task (N = 28), higher levels of mental fatigue were associated with higher ratings of perceived exertion (r = .38, p = .05). Findings provide insight into the effects of mental fatigue on people's exercise behaviours, illustrating a rational decision-making process that is dependent upon the subjective evaluation of the costs and benefits of engaging in physical activity or sedentary alternatives. / Thesis / Master of Science (MSc)

Contemporary models of declarative memory state that when initially learned, all novel information is encoded by the hippocampal system before being consolidated or transformed to depend on neocortical structures subserving semantic memory. Based on observations with functional magnetic resonance imaging (fMRI), this thesis presents evidence that novel associations may be directly encoded by the semantic system in humans. While the hippocampus is often involved in information processing at the early stages of learning, the semantic system is seen to encode associative memory traces in the first instance (chapter 2). Furthermore, it is proposed that the hippocampus is not involved in learning when associative information is gradually accumulated across a series of ambiguous events. This is characteristic of cross-situational learning (xSL) which allows for the acquisition of word-object associations (i.e. nouns) during infancy. It is shown that xSL is not well accounted for by a prominent model of contextual learning - the temporal context model (chapter 3). Additionally, fMRI data suggest that neocortical structures rather than components of the hippocampal system are preferentially involved in xSL compared to traditional methods of training (chapter 4). Finally, it is suggested that rapid hippocampal learning mechanisms rely on specialised neuronal-microglial interactions. The administration of a microglial inhibitor (minocycline) was found to modulate hippocampal function and bias its use when other learning systems would have been more advantageous (chapter 5). Collectively, these findings suggest that the hippocampal system is specialised for rapidly encoding information that is explicitly provided, yet may not be recruited when associative information is collated across ambiguous events. At the same time, the neocortical semantic system may be able to learn new information at faster rates than previously thought. As such, it is hypothesised that amnestic patients may be able to acquire some forms of declarative material if presented in an appropriate manner.

Age-related decline in cognitive performance and brain structure can be offset by increased exercise. Little is known, however, about the cognitive and brain structural consequences of long-term high-effort endurance exercise. In a cross-sectional design, we recruited older adults who had been engaging in high-effort endurance exercise over at least twenty years, and compared their cognitive performance and brain structure with a non-sedentary control group similar in age, sex, education, IQ, depression levels, and other lifestyle factors. We hypothesized that long-term high-effort endurance exercise would protect against the age-related decline in memory, attention, and brain structure. Our findings, in contrast to previous studies, indicated that those participating in long-term high-effort endurance exercise, when compared without confounds to non-sedentary control volunteers, showed no differences on measures of speed of processing, executive function, incidental memory, episodic memory, working memory, or visual search. On measures of prospective memory, long-term exercisers performance suggested a self-imposed increase in effort, which did not impact on ability to complete the PM task. In complex attention tasks, they displayed a differential strategy to controls. Structurally, long-term exercisers only displayed higher diffuse axial diffusivity, an index of axonal integrity, than controls, but this did not correlate with any cognitive differences.

Cognitive process accounts of the advantages conferred by diagrams in problem solving and reasoning have typically attempted to explain an idealised user or a reasoning system that has equivalent to practised knowledge of the task with the target representation. The thesis investigates the question of how diagrams support users in the process of solving unpractised problems in the domain of probability. The research question is addressed by the design and analysis of an empirical study and cognitive model. The main experiment required participants (N=8) to solve a set of unpractised probability problems presented by combined text and diagram. Think-aloud and eye-movement protocols together with given solutions were used to infer the content and process of problem interpretation, solution interpretation and task execution strategies employed by participants. The data suggested that the diagram was used to facilitate problem solving in three different ways by: (a) supporting sub-problem identification, (b) supporting prior knowledge of diagrammatic sub-schemes used for interpreting a solution and (c) supporting the process of interpreting and testing the specific meaning of given problem instructions and self-generated solution instructions. These empirical data were used to develop cognitive models of canonical strategies of the three identified phenomena: • Sub-problem identification advantages are accounted for by proposing that the spatial semantics of diagrams coupled with competences of the visual-spatial processing system and opportunities for demonstrative interpretation strategies increase the probability of goal-relevant data being made available to central cognition for further processing. • Framing advantages are accounted for by proposing that represented diagrammatic sub-schemes (e.g. part-whole portions, icon-arrays, 2D containers etc.) facilitate access to existing prior knowledge used to frame, derive, and reason about information analogically within that scheme. • Advantages in instruction interpretation are related to the specificity of diagrams which support the opportunity to demonstratively test and evaluate the referential meaning of an instruction. The cognitive model also investigates and evaluates assumptions about the prior knowledge for solving unpractised probability problems; a representational scheme for addressing the co-ordination of sub-goals; a deictic problem representation to support online processing of environmental information, a meta-cognitive processing scheme to address self-argumentation and intention tracking and visual and spatial competences to address the requirements of diagrammatic reasoning. The implications of the cognitive model are discussed with regard to existing accounts of diagrammatic reasoning, probability problem solving (PPS), and unpractised problem solving.