Interactive effects of physical and mental workload on subjective workload assessment

Individuals arc often expected to perform complex tasks involving physical and mental demands, particularly with the ongoing implementation of technology. Subjective workload assessment measures have been used extensively in a single domain (e.g., mental or physical), but at present there are no validated techniques available for measuring overall workload in multi-task situations. This study investigated the interaction between physical and mental demands and the effects of such interactions when using existing subjective workload assessment tools. Two common assessment tools (Borg CR10 Scale and NASA-TLX) were used to record changes in perceived Workload. Thirty participants (ages 18-24 years) performed tasks involving the concurrent completion of a lifting task and mental arithmetic at four levels of physical and mental demand, respectively. Ratings using the Borg CR10 Scale, a uni-dimensional scale for the physical domain, were not substantially affected by the presence of additional mental task demands. NASA-TLX scores, based oil a multi-dimensional assessment approach that included a physical demand component, reflected the mental workload demands, but were also affected by the addition of a concurrent physical task. Furthermore, there were no significant differences between the weighted and unweighted scores. Further research is needed to determine tile broader utility of these tools in providing all assessment of overall workload.