Grip Force as a Measure of Stress in Aviation

Objective: We conducted an exploratory investigation of whether grip force could be an indicator of stress in aviation. Background: Pilots might experience stress when anticipating failure to meet task demands and therefore, higher levels of stress can be used as a trigger for engaging automatic assistance. An unobtrusive measure of stress in aviation might be the grip force pilots exert on the control stick that could increase due to the intensified muscle tonus that characterizes psychological stress. Method: Participants were randomly assigned to either an experimental or a control group and performed tracking tasks. Participants in the experimental group were told that as of the second half of the experiment their compensation for the experiment would partly depend on their performance. No such conditioning existed for the control group. Grip force was then measured using a sensor on the control stick. Results: Grip force significantly increased in the second half of the experiment in the experimental group, but decreased in the control group. Similar interaction between experimental group and experimental half was also evident with self-reported stress and galvanic skin response (GSR), yet increases within the experimental group were not significant. Grip force also moderately correlated with GSR, possibly suggesting that they responded to the same construct. Conclusion: Findings provided a preliminary indication that grip force could be used to measure stress in aviation, meriting further research exploration.