Physiological reflections of mental workload.

Studies reporting physiological responses as reflections of mental workload are reviewed briefly. The differing measures are located in a two-dimensional space whose axes represent first, practical application and second, relevance to actual central nervous system activity as viewed from spatial and systemic congruence. Traditional methods such as those using heart rate are identified as the most practical current measures, while evoked cortical potentials emerge as superior upon the latter axis. The potential of auditory canal temperature as an optimal composite measure is explored.