Contribution
The Pupillary Unrest Index as an Objective Measure of Fatigue
* Presenting author
Abstract:
Fatigue is a common phenomenon influenced by various factors, such as a workday or cognitively demanding tasks like effortful listening. While subjective scales like the Fatigue Assessment Scale (FAS) are widely used to assess perceived fatigue, the availability of objective measures remains limited. The Pupillary Unrest Index (PUI), derived from the spontaneous pupil diameter’s fluctuation over time, reflects changes of the autonomic nervous system and shows promise as an objective fatigue measure.This contribution presents two studies to evaluate the PUI’s potential regarding its sensitivity towards both daily fatigue and task-induced fatigue. In the first study, participants’ PUI were measured before and after a workday; in the second, before and after completing speech tests. Additional metrics included baseline pupil dilation, mean pupil dilation, subjective ratings like FAS scores, speech recognition, and subjectively rated listening effort. Results showed a significant PUI increase after the workday, indicating greater fatigue. In contrast, speech tests did not significantly affect the PUI values. This aligns with FAS scores, which reflect general fatigue and showed a negative correlation with PUI values. These findings support the PUI as a stable, objective measure of daily fatigue and highlight its potential for broader applications in fatigue research.