Activity Ratio to Measure Physical Demand of Cognitive Workload.

Human-machine systems (HMS) need trustful cooperation between humans and machines for achieving a goal. Establishing such trust demands the machines’ adaptivity to the cognitive workload (CWL) of the humans. The CWL is conventionally measured as self-reported scores from a NASA-TLX questionnaire, susceptible to individual subjectivity. In contrast, logged brainwaves are useful for measuring the CWL objectively. However, there is a literature gap of mapping the brainwaves to a CWL factor - i.e., physical demand. As a feasibility, we thus proposed an activity ratio (AR) to measure the physical demand from the brainwaves. Statistical analyses indicated significant correlations between the AR and self-reported scores of the physical demand, compared to a well-known engagement ratio. This finding implied the feasibility of the AR to measure the physical demand.