Effect of Physical and Mental Workload Interactions on Human Attentional Resources and Performance

Many tasks in the real world require simultaneous processing of mental information alongside physical activity. Most of researchers have studied the impact of physical activities on simple cognitive tasks, but have neglected other important influences (such as different attentional resource pools, as well as gender). Therefore, this thesis proposes a new model that investigates the combined impact of physical and mental workload on different attentional resources (visual and auditory, verbal and spatial). This thesis presents three experimental studies that examined the effects of physical and mental workload interactions, as well as gender, on visual tasks performance and auditory tasks. This thesis uses different methods to evaluate the impacts of workload interactions on task performance: performance measure, physiological parameters and brain activity (Near-Infrared Spectroscopy (NIRS) method) and subjective assessment tools. Finally, this thesis translates the experimental studies setting into a field study to validate the model. Based on the experimental results, this research creates a new theoretical model that illustrates in general that physical activity is beneficial for performance on cognitive tasks (visual and auditory), particularly at low levels of workload interactions, while other workload interactions lead to worse performance on cognitive tasks. However, when physical activity was introduced, performance at the medium level of mental workload was equivalent to that in the low mental workload condition; furthermore, at the low mental workload, there were no differences in performance between low and medium physical workloads. The general pattern of results suggests that physical workload leads to better performance in these medium-demand conditions up to the higher level in the low-demand condition. A mechanism for this effect is proposed based on physiological arousal and brain oxygenation. This thesis further suggests that the NIRS is a valuable technique to reflect the influence of physical and mental workload interactions on brain activity. Finally, this thesis demonstrates the translation of experimental findings into a field setting to verify the new model as well as to make recommendations for job design.