Inaug.-diss.--Heidelberg. / "Sonderabdruck aus Kraepelin, Psychologische arbeiten. I. bd. 2. heft."

Aversion is a complex phenomenon that arises over time through performance of cognitively demanding tasks and has been associated with the mechanisms of mental fatigue and compensatory control. However, little is known about this sensation to dissociate from the task at hand and the causation thereof. It is apparent that aversion is a negative state for the operator and could result in decreased performance and productivity. Through identification of factors that contribute to aversion when performing cognitively demanding tasks, recommendations to reduce design deficits may be employed to promote worker wellbeing and further advance performance and productivity. The current study examined possible factors that may influence aversion experienced through execution of cognitive tasks. A subsequent aim of this study was to assess a possible cause of aversion. The cause of aversion was hypothesized to be related to efficiency, namely the perception of efficiency when performing tasks and actual efficiency calculated through performance of tasks in relation to the expenditure of effort. Four investigations were undertaken with a non-repeated design between investigations and a repeated design within investigations. The first investigation was an analysis of the effect that stimulus cycling had on the aversion experienced. This consisted of a proof reading task with two conditions varying in the repetitiveness of the text, therefore, allowing an analysis as to how aversion is altered by the provision of a new stimulus to the participants. Investigation two investigated the effect that task difficulty imposed on aversion experienced. This comprised of two conditions with varied difficulty that were implemented through a driving simulator tracking task with difficulty altered by the width of the driving lane. The effect of performance feedback on the aversion experienced towards a task was the focus of the third investigation. The effect on aversion experienced was assessed through a driving simulator tracking task with a condition providing feedback of performance to participants and a condition with no knowledge of performance. The final experiment evaluated the effect of task alternations on aversion. This experiment was conducted through alternations between a driving simulator tracking task and a choice reaction task. The choice reaction tasks required participants to identify critical and non-critical stimulus. Four conditions were required for this experiment and were made up of two conditions where there was provision of alternation that varied in frequencies between the two tasks (medium alternation condition and fast alternation condition) and two conditions where no alternations were instated (driving simulator task condition and choice reaction task condition). Separations between all testing conditions were three or more days apart with sixty participants distributed between the investigations. Test duration of each condition was 30 minutes. Subjective data was recorded throughout investigations for all conditions in the form of aversion, subjectively perceived efficiency and rate of perceived exertion. Objective data was collected in the form of physiological responses and performance of tasks for the analysis of objective efficiency. For factors influencing aversion analysis, no differences in aversion experienced were found for the task difficulty and performance feedback investigations. Aversion was found to be less for the changes imposed through the task cycles and task alternation investigations. This concludes that aversion is aggravated through monotonous tasks and by a change of the stimulus or the structure of the cognitive tasks provided to operators; aversion can be alleviated. The results for the cause of aversion analysis found no difference in objective efficiency over time, with a subsequent decrease in perceived efficiency associated with the increasing aversion. Inference from these findings suggest that aversion cannot be attributed to objective inefficiency of task performance, however it can further be assumed that perception of actual efficiency is inaccurate. Perception of efficiency however had a large influence on the sensation of aversion. Aversion is seen to be more of a product of time on task, however whether this is mechanism of fatigue or compensatory control is still to be determined.

Mental fatigue has been proven to be highly prominent during shift work, due to long, irregular working hours and disruption of the circadian rhythm. Measuring mental fatigue has been a challenge for many years, where commonly cognitive test tasks are used to assess mental fatigue. Moreover, these test tasks do not isolate where fatigue is occurring during human information processing. The human information processing system consists of four core stages, each of which requires numerous cognitive functions in order to process information. The Human Kinetics and Ergonomics Department at Rhodes University has developed six cognitive test tasks where each isolates a cognitive function: an accommodation test task, a visual detection test task, a reading test task, a memory test task, a tapping test task and a neural control test task. The cognitive functions include: eye accommodation, visual discrimination, visual pattern recognition, memory duration, motor programming and peripheral neural control. General task-related effect can also be examined for each of these cognitive test tasks which include choice reaction time, visual detection, reading performance, short-term memory, motor control and tracking performance. Additionally, a simple reaction time test task has been developed to analyse simple reaction time. This test task does not isolate a cognitive function. One or more parameters can be examined for each cognitive function and task-related effect. The first aim of this study was to validate numerous cognitive test tasks for mental fatigue in a simulated shift work laboratory setting. The second aim was to assess the validated cognitive test tasks in Phase 1 in a field-based rotational shift work setting. Parameters revealing sensitivity to mental fatigue would be validated for mental fatigue applied to rotational shift work and would be inserted into an assessment tool. In the laboratory setting, the seven cognitive test tasks were examined on four different types of shift work regimes. The first regime was a standard eight-hour shift work system, and the other three were non-conventional shift work regimes. Participants (n = 12 per regime) were required to complete one day shift followed by four night shifts, where testing occurred before and after each shift and four times within each shift. The cognitive test tasks revealing sensitivity to fatigue included: visual detection test task, reading test task, memory test task, tapping test task, neural control test task and simple reaction time test task. The testing of Phase 2 was conducted in three different companies, where each performed a different type of rotational shift work. The six cognitive test tasks validated for mental fatigue in Phase 1 were tested before and after work for each shift type within the rotational shift work system adopted by each company. Company A (n = 18) and Company B (n = 24) performed two-shift rotational shift work systems, where the shift length of Company A was 12-hours and the shift length of Company B was irregular hours. Company C (n = 21) performed an eight-hour three-shift rotational shift work system. Nine parameters revealed fatiguing effects and were inserted into the assessment tool, five of which provided information on a specific cognitive function: error rate for visual discrimination, processing time for visual pattern recognition, error rate for visual pattern recognition, impact of rehearsal time on memory recall rate for memory duration and the high-precision condition for motor programming time. The remaining four parameters provided information on general task-related effects: reading speed for reading performance, recall rate for short-term memory, reaction time for motor control and simple reaction time. Therefore, an assessment tool comprising nine parameters was validated for mental fatigue applied to rotational shift work, where five of the parameters were able to isolate exactly where fatigue was occurring during human information processing and the other four parameters were able to assess fatigue occurring throughout the human information processing chain.

I Sverige insjuknar ca 25 000 människor varje år i stroke och en vanlig konsekvens är hjärntrötthet. Det finns forskning kring hjärntrötthet men begränsad forskning om hur arbetsterapeuter arbetar med dessa individer. Syftet med studien var att beskriva arbetsterapeuters erfarenheter av att arbeta med personer som drabbats av hjärntrötthet efter stroke. Fem arbetsterapeuter intervjuades varefter intervjuerna analyserades med kvalitativ innehållsanalys. Resultatet visade att en central del i arbetet var att informera och stödja de drabbade. En viktig del i arbetet innan implementeringen utav olika strategier, var att låta personen få insikt i den nya rollen. Insikten ansågs avgörande för personens process framåt. De strategier som erbjöds syftade till att individerna skulle kunna hantera sin hjärntrötthet och uppleva en fungerande vardag. En slutsats är att anhörigas förståelse och stöd i rehabiliteringsprocessen är viktig. Arbetsterapeuter beskriver att ett klientcentrerat förhållningssätt är avgörande eftersom hjärntröttheten påverkar varje individ olika. Därför betonades att en noggrann kartläggning är av största vikt.

Bakgrund: Hjärntrötthet är en vanlig konsekvens efter stroke. Hjärntrötthet innebär att personen är mentalt trött och hjärnan orkar inte processa flera saker samtidigt vilket påverkar personens vardag. Hjärntröttheten kan beskrivas som en dold funktionsnedsättning och det kan vara svårt för personen samt omgivningen att förstå hjärntröttheten. Med hjälp av arbetsterapeutiska strategier så kan personer med hjärntrötthet lära sig att hantera sin trötthet och skapa en meningsfull fungerande vardag. Syfte: Syftet var att beskriva erfarenheter av att leva med hjärntrötthet efter stroke samt arbetsterapeutiska strategier som underlättar vardagen för personer som lever med hjärntrötthet efter stroke. Metod: En litteraturöversikt valdes som metod. Datainsamlingen gjordes i fem databaser som innehöll vetenskapliga artiklar om medicin och hälsa. Åtta kvalitativa studier och en RCT-studie inkluderades efter inklusionskriterierna och kvalitetsgranskningen. Studierna analyserades i fyra steg och analysen resulterade i fyra kategorier. Resultat: Artiklarna kommer från olika länder, publicerade mellan 2008 och 2021 och samtliga deltagare var över 18 år. Analysen resulterade i fyra kategorier: Erfarenhet av hjärntrötthet, Vila och återhämtning, Anpassad miljö och Val av aktiviteter. Resultatet visade att deltagarna hade svårt att hantera vardagen och hjärntröttheten påverkade aktivitetsutförandet. Flera deltagare upplevde oro och rädsla för att drabbas av en ny stroke i framtiden. Slutats: Resultatet visade att personer som lever med hjärntrötthet upplevde svårigheter med att hantera vardagen och det påverkade personernas aktivitetsutförande samt deltagandet i sociala interaktioner. Flera av deltagarna i de granskade studierna uppgav att hjärntröttheten inte gick att vila bort och att det var svårt att veta när hjärntröttheten uppstod. Vidare så upplevde deltagarna att miljön påverkade hjärntröttheten både positivt och negativt beroende på vilken miljö de befann sig i. Litteraturöversikten visade att det fanns begränsad forskning om arbetsterapi och rehabilitering för personer med hjärntrötthet efter stroke. Arbetsterapeuterna hade en viktig roll i rehabiliteringen för att lära ut olika strategier för att hantera hjärntröttheten. / Background: Mental fatigue is a common consequence after a stroke. Mental fatigue implies that the person is mentally tired and the brain is not able to process several things at the same time, which affects the person's everyday life. Mental fatigue can be described as a hidden dysfunction and it could be difficult for the person and the surroundings to understand the mental fatigue. Strategies from occupational therapists can support people with mental fatigue to manage their fatigue and create a meaningful and functioning everyday life. Purpose: The purpose of the literature review was to describe experiences of living with mental fatigue after a stroke and occupational therapy strategies that make everyday life easier for people living with mental fatigue after a stroke. Method: A literature review was chosen as a method. The data collection was done in five databases that contained scientific articles in medicine and health. Eight qualitative studies and one RCT study were included according to the inclusion criteria and the quality review. The studies were analyzed in four steps and the analysis resulted in four categories. Results: The articles come from different countries, published between 2008 and 2021 and all participants were over 18 years old. The analysis resulted in four categories:  Experience of mental fatigue, Rest and recovery, Adapted environment and Choice of activities. The participants had difficulty coping with everyday life and the mental fatigue affected the activity performance. Several participants experienced anxiety and fear of suffering a new stroke in the future. Conclusion: The results showed that people living with mental fatigue had difficulty managing everyday life and it affected people’s activity performance as well as participation in social interactions. Several participants in the studies stated that the mental fatigue could not be rested and that it was difficult to know when the mental fatigue occurred. Furthermore, the participants experienced that the environment affected mental fatigue both positively and negatively depending on the environment they were in. The literature review showed that there was limited research on occupational therapy and rehabilitation for people with mental fatigue after stroke. Occupational therapists had an important role in rehabilitation to educate different strategies for managing mental fatigue.

Syfte: Studiens syfte var att beskriva arbetsterapeuters erfarenheter av arbetsterapeutiska interventioner för hjärntrötthet hos personer med postcovid.  Metod: En kvalitativ design valdes för att besvara studiens syfte. Urvalet skedde genom snöbollsurval och målinriktad provtagning med förutbestämda kriterier. Totalt sex yrkesverksamma arbetsterapeuter deltog i studien. Insamling av data skedde genom semistrukturerade intervjuer med stöd av intervjuguide. Samtliga intervjuer spelades in och transkriberades för att sedan analyseras enligt kvalitativ innehållsanalys. Resultat: Analyserad data resulterade i tre huvudkategorier med respektive underkategorier. Huvudkategorierna bestod av; “Psykoedukativa interventioner” som beskrev interventioner i form av information om postcovid, hjärntrötthet samt aktivitetsbalans och meningsfullaaktiviteter. “Hitta energibesparande strategier i vardagen” som beskrev kognitiva strategier, anpassningar av miljö och aktivitet samt interventioner riktade mot återhämtning. Den sista kategorin var “Interventioner för yttre socialt stöd” och beskrev interventioner som riktade sig mot arbete och sjukskrivning, samt mot närstående och stöd från personer med samma tillstånd. Slutsats: Arbetsterapeutiska interventioner för hjärntrötthet vid postcovid kan delas in i tre huvudsakliga kategorier som beskriver olika typer av interventioner som alla uppfyller olika syften. Dessa interventioner återfinns hos andra patientgrupper med hjärntrötthet men anpassas ofta för patienter med postcovid. Studiens resultat jämfört med litteratur visar att arbetsterapeuter besitter stor kompetens för rehabilitering av denna patientgrupp iochmed deras personcentrerade förhållningssätt samt kunskaper om aktivitetsbalans och vardagsergonomi. Arbetsterapeutiska interventioner bör därför prioriteras i rehabilitering av denna patientgrupp. Större studier behövs för att vidare stödja detta, samt se över effekten av arbetsterapeutiska interventioner för hjärntrötthet vid postcovid. / Purpose: The purpose of this study was to describe occupational therapists’ experiences of occupational therapy interventions aimed at mental fatigue for people with postcovid. Method: A qualitative design method was used to answer the purpose of this study. Sampling was done through snowball sampling and purposive sampling with predetermined criteria. A total of six occupational therapists participated in the study. Collection of data was done through semistructured interviews with support from a premade interview guide. All interviews were recorded and transcribed to then be analyzed by qualitative content analysis. Results: Analyzed data resulted in three main categories with respective subcategories. The main categories are: “Psychoeducational interventions ” that described interventions in the form of information regarding postcovid, mental fatigue and also activity balance and meaningful activities. “Finding strategies for energy conservation in everyday life” that described cognitive strategies, adaptations of environment and occupations and also interventions aimed at rest. The last category was “Interventions for external social support” which described interventions aimed at work and sick leave, and also family and support from people with the same condition.                           Conclusion: Occupational interventions for mental fatigue in people with postcovid can be separated into three main categories that describe different forms of interventions that all fulfill different purposes. These interventions can also be found in other patient groups that experience mental fatigue but are often adapted for patients with postcovid. The result of the study compared to the literature shows that occupational therapists possess great competence for rehabilitation of this patient group through their person-centered approach and knowledge about activity balance and ergonomics. Occupational therapy interventions should therefore be prioritized in the rehabilitation of this patient group. Larger studies are needed to further support this, and to study the effect of occupational therapy interventions aimed at mental fatigue forpeople with postcovid.

To date, mental fatigue has been shown to lead to a general decline in cognitive processing and motor performance. The goal of the current research was to establish the impact of mental fatigue on the contributions of explicit (i.e., conscious strategy) and implicit (unconscious) processes to visuomotor adaptation. Participants were divided into Mental Fatigue (MF) and Control groups. Mental fatigue was induced through a time load dual back task (TLDB), in which participants were required to respond as quickly and accurately as possible to letters based on recall of previously presented letters, as well as digits displayed on the screen in a choice reaction time task. The TLDB task lasted for 32 minutes, and the Control group watched a documentary for a similar length of time. Subjective feelings of mental fatigue, as indicated on a self-report scale, demonstrated that mental fatigue was significantly higher for the MF group after completion of the TLDB task. There was no similar increase in mental fatigue for the Control group. The increased mental fatigue was associated with decreased visuomotor adaptation to a 40° cursor rotation and retention of visuomotor adaptation. In particular, participants in the MF group adapted their reaches to a lesser extent early in training compared to the Control group and demonstrated less retention of visuomotor adaptation following a 20-minute rest. Furthermore, correlational analyses established that greater mental fatigue reported by participants in the MF group was associated with less explicit adaptation and greater implicit adaptation. Taken together, these results suggest that mental fatigue decreases the ability to engage in explicit processing, limiting the overall extent of visuomotor adaptation achieved.

More than half of the world's population works full time and spends about one-third of their weekdays at workplaces (International Labor Organization, 2022). Mental disorders are one of the health problems that have emerged among working populations (World Health Organization, 2022). Previous empirical research and theories demonstrated that nature exposure positively impacts human health and wellbeing (Kaplan and Kaplan 1989). Green roofs can be one of the most easily accessible nature places for office workers in city centers. This study examines the relationship between green roofs and work-related distress, mental fatigue, and restoration. An online survey of 179 employees was used to evaluate the relationship between exposure to six different green roofs and employee work-related distress, mental fatigue, and mental restoration. The results show that the average time spent on green roofs and the frequency of visits have statistically significant relationships with the mental restoration. / Doctor of Philosophy / More than half of the world's population works full time and spends about one-third of their weekdays at workplaces (International Labor Organization, 2022). Mental health issues are one of the health problems that have emerged among employees (World Health Organization, 2022). Previous research and theories demonstrated that nature contributes to human health and wellbeing in a very positive way (Kaplan and Kaplan 1989). This study investigates the relationship between green roofs and work-related stress and mental fatigue. This study evaluates employees' perceived stress and mental fatigue at work, their perception of onsite green roofs, and the restorative capacity of workplace green roofs using a 32-item online survey. 179 employees from four companies with at least one onsite green roof each answered the survey. The results showed that the average time spent on green roofs per visit, the frequency of visits, employees' attitudes and perceptions towards workplace green roofs, the organization's relevance with nature, the presence of diverse species on the green roof, and employees' knowledge about green roofs are related to the perceived restoration capacity of the green roof. The study contributes to understanding the relationship between the restorative capacity of green roofs and work-related psychosocial outcomes, employees' green roof use patterns, preferences, and green roof design attributes. Green roof designers, the green roof industry, and business owners can benefit from the study findings and implications to create more restorative green roofs, as well as happier and healthier workplaces.

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.

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.