Cardiovascular and eye activity measures as indices for momentary changes in mental effort during simulated flight

Abstract

This study examines effects of momentary changes in mental effort on cardiovascular and eye activity measures. A total of 19 male pilots performed an instrument flight task. Task load was manipulated by having the pilots perform flight manoeuvres of varying complexity. Multilevel analyses demonstrated clear effects of momentary changes in mental effort on both the cardiovascular and the eye activity measures. An increase in task load resulted in an increase of heart rate and a decrease in heart rate variability, mean dwell time and fixation duration. Heart rate differentiated between resting period and task execution. Heart rate variability from short data segments provided more insight in intermediate levels of mental effort. The eye activity measures were sensitive to intermediate levels of mental effort as well. Attitude changes resulted in an increase of mean dwell time and mean fixation duration. Task analysis is required to use eye measures as valid indices of mental effort. Having indications of the effects of changing mental demands during daily work of operators is of great importance nowadays. This paper presents an approach to estimate such effects on the basis of heart rate and eye activity measures. In particular, the use of averaged short-term heart rate variability measures is a relatively new aspect.

Keywords:

• mental workload
• mental effort
• heart rate
• heart rate variability
• eye activity
• subjective ratings

Acknowledgements

The authors wish to thank the staff members of the Center for Man and Aviation (Soesterberg, The Netherlands) for providing them with the logistical support for the completion of this study. They also wish to thank Evelien Kums, Michiel de Leeuw and Siemen Henk Sikkema for their fruitful cooperation in the study design and data collection and Hedwig Hofstetter for the pre-study on short-segment HRV analysis. Finally, they wish to thank the selection candidates and Air Force cadets who participated in this study.