Assessment of mental workload based on a model of autonomie regulations on the cardiovascular system

Quantitative assessment of mental workload (MWL) is helpful in improving the usability of computer systems, the working environment, and work schedule management. We have been investigating the changes in autonomic indices such as heart rate, blood pressure and their variabilities induced by MWL. We found that the multidimensional use of these indices is useful to assess MWL. However, most of the indices are multiply regulated by the autonomic nervous system and influenced by other indices through feedback loops. So if careful considerations are not made, their changes which are not induced directly by MWL would be misunderstood. For that reason, we introduced a physiological model of autonomic regulations on the cardiovascular and respiratory systems to obtain new measures more directly related to MWL, such as sympathetic tone, vagal tone and baroreflex gains.