Test by: Vera Rick, M.A. – Research Assistant – Faculty of Mechanical Engineering – Institute of Industrial Engineering and Ergonomics (IAW) – RWTH Aachen University

Increasing digitalisation and the development of new forms of work organisation have been confronting the world of work with profound changes. Whereas in the past employees were more likely to perform physical work, today psychological stress factors are increasingly coming to the fore. One aspect of psychological stress is mental workload, which plays an increasingly important role in the design of workplaces.

Real-time measurement of mental workload would make it possible to act directly and avoid overload in the short term, which could consequently lead to mistakes. Furthermore, it can guarantee a healthier working life in the long term, and thus prevent absences from work due to illness. A reliable and real-time measurement of mental load is therefore highly desirable.

Our eyes can tell us a lot about our mental state. The pupil size in particular has proven to be a useful indicator. The indication of pupil diameter on mental load goes back to Hess and Polt (1964), who demonstrated the connection between pupil dilatation and task difficulty. The authors prove that the pupil increases with problem difficulty. Kahneman and Beatty (1966) suggested that the pupil diameter is a “very effective index of the momentary load on a subject as they perform a mental task”. In general, the pupil size can be considered as a valid index of mental workload as it has been reported in many different contexts related to cognition in future research.

Therefore, the aim of the WorkingAge project is to integrate an eye tracker into the WAOW tool that measures mental strain and provides real-time feedback, which will ensure the short-term and long-term well-being of employees.

In order to make this possible, the WorkingAge project is testing the use of an eye tracker that measures mental workload within different working scenarios. The laboratory studies will soon be carried out at the RWTH Aachen University. The aim is to get an overview of the possible areas of usage as well as to compare different types of eye trackers regarding their validity and their acceptance for future users. Finally, the laboratory tests will help determine threshold values, which can be used for real-time evaluation of the measured raw data, so that the user is given the opportunity to obtain direct feedback on his or her cognitive condition.


Hess, E. H., & Polt, J. M. (1964). Pupil size in relation to mental activity during simple problem-solving. Science143(3611), 1190-1192.

Beatty, J., & Kahneman, D. (1966). Pupil diameter and load on memory(Pupillary diametric size as indicator of load on human memory). Science154, 1583-1585.

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