Steering in the dark: The impact of environmental luminance on driver behavior through optical flow analysis.

The visual perception and steering behavior of drivers are known to be influenced by environmental lighting, but the underlying perception mechanisms, particularly the role of optical flow under low-luminance conditions, remain insufficiently understood. In a simulated driving experiment, 32 participants were exposed to five controlled luminance levels while their eye movements and driving performance were recorded. The results indicate that lower environmental luminance leads to prolonged gaze duration, a wider distribution of gaze points, and an increase in lateral steering errors. At moderate luminance, drivers exhibited enhanced optical flow perception and improved steering accuracy. However, under low luminance, degraded optical flow weakened the coupling between gaze and self-motion, caused a misalignment between gaze and vehicle motion, leading to reduced steering accuracy. These findings advance previous work by demonstrating that luminance not only affects gaze behavior but also modulates visual perception through its impact on optical flow processing. These insights may support the development of adaptive driver training programs and human-centered driver assistance systems that respond to perceptual challenges in low-luminance environments.