Effects of physical workload on working memory performance
신체적 부하가 작업기억 과업 수행능력에 미치는 영향

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공과대학 산업공학과
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서울대학교 대학원
backpack weightpostural loadingmultitaskingmental task performanceworking memory
학위논문 (박사)-- 서울대학교 대학원 : 공과대학 산업공학과, 2018. 2. 박우진.
Many workers, including soldiers, firefighters, and policemen, perform demanding physical work tasks while carrying heavy equipment. For example, soldiers carry around 30-50kg of military gear and perform prolonged standing and marching, and many other postural and movement tasks. The occupational activities of the workers carrying extra weights are not limited to physical tasks. They also perform various mental tasks along with physical ones – the mental and physical tasks are conducted close in time and often simultaneously. For example, in the case of soldiers, the mental tasks include comprehending dynamic battlefield situations, communicating information, making decisions, issuing and receiving operational orders, etc.

In a similar context, workers in the medical field such as doctors, nurses, and pharmacists frequently multitask and are faced with physical workload in addition to their high level of mental workload. For example, nurses are required to complete physical tasks such as lifting patients for transfer out of bed and from the floor, while completing mental tasks, all in an urgent and busy work environment.

As mentioned above, many human work tasks consist of a physical component (physical sub-tasks) and a mental component (mental sub-tasks) – rarely are there work tasks that only requires the use of one component. Therefore, workers tend to experience both physical and mental workload while completing their work task.

From the human information processing (HIP) point of view, physical and mental tasks constituting a work activity are thought to be mutually influential rather than independent. Indeed, such mutual relationships have been empirically demonstrated in many previous studies. The previous results on the inter-relationship between the concurrent physical and mental tasks lead to the hypothesis that the body-worn equipment weight or postural loading affects the performance of some of their mental tasks. Understanding how the body-worn equipment weight or postural loading affects the performance of different mental tasks will provide a basis for designing work tasks to maximize safety, performance and worker wellbeing. Despite the significance, however, few studies seem to have examined such relationships.

Therefore, this study aimed to empirically investigate the effects of body-worn equipment weight or postural loading on a workers performance of basic working memory tasks while the worker is simultaneously performing a certain physical task. To accomplish these objectives, two major studies were conducted.

In study 1, the effects of body-worn equipment weight on the performance of basic working memory tasks were examined. A backpack was adopted as a representative piece of body-worn equipment as it is widely used among workers, including soldiers and firefighters. Three types of physical tasks were considered in this study. They were flat-surface standing, walking along a predetermined route, and walking along a straight route, which are representative physical tasks performed by various workers including soldiers and firefighters. Also, three types of working memory tasks were considered so as to examine the different sub-components of the working memory system, that is, the visuo-spatial sketchpad, phonological loop and central executive systems. The results of data analyses showed that backpack weight affected working memory task scores differently in regards to the type of working memory task and physical task. Overall, working memory task scores had a tendency to decrease as backpack weight increased.

In study 2, the effects of postural loading on the performance of basic working memory tasks were investigated. In the case of the physical task, a specific posture was held for a predetermined amount of time, and four posture groups were considered, each with a different amount of postural loading. Three types of working memory tasks were considered as in study 1. The data analyses revealed significant effects of postural loading on the scores of the working memory tasks. As postural loading increased, all of the three working memory task scores decreased.

The study findings entail that reducing the body-worn equipment weight or postural loading can positively impact the worker's mental task performance in addition to reducing the worker's bodily stresses and the risks of work-related musculoskeletal disorders. This is especially important for situations where workers perform critical mental tasks along with demanding physical tasks, as in the work activities of soldiers, firefighters, pilots and medical team. Such results may contribute to the practical design of products or systems which require multitasking, by providing an experimental basis about the increased mental performance when using such products (or reducing the decrease of mental performance). Such results also provide empirical evidence about possible improvements for work tasks where multitasking of physical and mental tasks occur
this may be in the form of work station design or working posture improvement.
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College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Industrial Engineering (산업공학과)Theses (Ph.D. / Sc.D._산업공학과)
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