The Eyes Tell The Load: Saccadic Intrusions as Indicators of Cognitive Demand in Latency

This study investigates the correlation between mental workload and saccadic intrusions recorded through eye tracking during the landing of a remotely piloted aircraft (or also called as Unmanned Aerial Vehicles UAVs) under communication delay conditions. The experiment simulates a satellite link operation with a 2 -second delay between the pilot's command and the aircraft's response, a condition that significantly increases task complexity and cognitive demands. Three configurations of an adaptive Head-Up Display (HUD) were evaluated to identify which one best supports pilot performance under latency conditions. Objective measures of saccadic intrusions were correlated with subjective assessments of mental workload obtained through the NASA-TLX, SWORD, and Instantaneous SelfAssessment (ISA) questionnaires. The results indicated a convergence among the subjective metrics ( r > 0.98 ). A strong negative correlation was observed between perceived workload and the frequency of saccadic intrusions ( r=−0.88 ), providing evidence of the cortical suppression phenomenon under high visual demand. The 30second temporal analysis confirmed that the No-HUD condition imposes a statistically significant state of attentional tunneling ( ρ = −0.56 ; p=0.0456 ), whereas the HUD interfaces mitigated this oculomotor rigidity, allowing more natural and less fatiguing visual processing.

Keywords: Mental workload, Eye tracking, Saccadic intrusions, Human-machine interface, Subjective questionnaires.