Investigating the influence of cognitive demands and personal factors on work-body postures

Abstract

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.