Driver Visual-Cognitive Distraction Monitoring: The VICODEV Index

This work introduces “VIsual-COgnitive Distraction through Eye-tracking and Vehicular measurements” (VICODEV), an interpretable, statistically driven index combining five vehicular and behavioural measurements to estimate induced visual-cognitive distraction. The index was developed through an experimental campaign at the dynamic driving simulator of Politecnico di Milano using an Instrumented Steering Wheel, eye-tracking glasses, an electroencephalograph, and an electrocardiograph. Thirty-five novice drivers were recruited for the tests. Alongside the primary driving task, drivers performed five repetitions of a secondary “Clock Task”, inducing visual-cognitive distraction. During each secondary task, participants solved mathematical operations displayed on a tablet inside the cockpit. Twenty-one measurements were collected to describe induced distraction, including vehicular, behavioural, and physiological types. The Wilcoxon Signed Rank Test revealed twelve measurements with statistically significant trends between normal and induced distracted driving. Five measurements were then selected considering real-time in-vehicle applicability, namely Standard Deviation of Lateral Position of the vehicle’s center of gravity to the lane centerline, standard deviation of steering wheel grip force, Eyes Off-Road Time, rate of high-velocity eye movements, and mean duration of low-velocity eye movements. VICODEV combines these five measurements via canonical discriminant analysis, assessing induced visual-cognitive distraction every 40 ms. Leave-one-repetition-out cross-validation achieved an average recall of 99.47% and accuracy of 95.20%, confirming the index consistency across secondary task repetitions. Leave-one-subject-out cross-validation yielded a median Area Under the Receiver Operating Characteristic Curve of 82.9%, showing the index’s ability to identify shared patterns across the tested population. This study offers a standardised reference to support DMS design, evaluation, and comparison.