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Item Investigating the influence of cognitive demands and personal factors on work-body postures(Montana State University - Bozeman, College of Engineering, 2021) Nino, Luisa Valentina; Co-chairs, Graduate Committee: David Claudio and Scott Monfort; Frank Marchak and David Claudio were co-authors of the article, 'Evaluating physical and mental workload interactions in a sterile processing department' in the journal 'International journal of industrial ergonomics' which is contained within this dissertation.; Frank Marchak and David Claudio were co-authors of the article, 'Association between perceived workload and adverse body postures' in the journal 'Proceedings of the International Symposium on Human Factors and Ergonomics in Health Care' which is contained within this dissertation.Mental workload is a broad concept used by human factors and ergonomics professionals. It has become a topic of increasing importance since the introduction of technology in modern working environments. Mental workload assessment is an important component in the design of occupational tasks since inappropriate levels can cause errors, incidents, and be responsible for occupational diseases and musculoskeletal disorders. Until now, research studies have explored the effects of physical activity on mental workload. No study has analyzed the effects of mental workload on body postures even though studies have stated that in response to new information from the workplace environment, the human body orients in the direction of a stimulus, and this orientation reaction could affect the ongoing activity. This dissertation looked to 1) determine if psychosocial work factors affect perceived mental workload, 2) determine if changes in perceived mental workload generated changes in the body postures undertaken to perform an activity, and 3) explore if individual factors such as age, sex, personality traits, and anxiety mediate or exacerbate the influence of psychosocial work factors. Thirty-two participants performed two physical activities under four levels of mental workload. The results indicate, for the first time, that an increase in the perception of mental workload is associated with worse body postures that consequently could lead to work-related musculoskeletal disorders (WMSDs). Regarding the potential influence of individual factors, differences were not observed between mental workload conditions. However, individual characteristics such as anxiety, personality traits, and sex exhibited higher contributions to changes in perceived mental workload and body postures. This study is novel and contributes to overcoming an important shortcoming in the field of mental workload by considering the influence of psychosocial factors, keeping the physical load constant, on the perception of mental workload and its influence on body postures. This interaction between perceived mental workload and its effects on physical risk should be considered in occupational settings since often, employees are exposed to concurrent physical and mental demands that increase the likelihood of developing WMSDs.Item Driving in a simulator versus on-road : the effect of increased mental effort while driving on real roads and a driving simulator(Montana State University - Bozeman, College of Engineering, 2015) Mueller, Jessica Anne; Chairperson, Graduate Committee: Laura StanleyThe objective of this thesis is to study human response to increased workload while driving in a driving simulator compared to real world behavior. Driving simulators are a powerful research tool, providing nearly complete control over experimental conditions-- an ideal environment to quantify and study human behavior. However, participants are known to behave differently in a driving simulator than in an actual real-world scenario. The same participants completed both on-road and virtual drives of the same degree of roadway complexity, with and without a secondary task conditions. Data were collected to describe how the participants' vehicle-handling, gaze performance and physiological reactions changed relative to increases in mental workload. Relationships between physiology and performance identified physiological, performance, and gaze-related metrics that can show significant effects of driving complexity, environment, and task. Additionally, this thesis explores the inadequacy of multinomial predictive models between the simulator and instrumented vehicle. Relative validity is established in the performance-physiology relationship for on- and off-road fixation frequencies, but few correlations between the simulator and instrumented vehicle are apparent as mental workload increases. These findings can be applied to the real world by providing specific variables that are adequate proxies to detect changes in driver mental workload in on-road driving situations; valuable for in-vehicle driver assistance system research. Overall, the simulator was a suitable proxy to detect differences in mental workload in driving task; and initial steps have been taken to establish validity, and to supplement on-road driving research in these high-demand driving scenarios.