Head-Up Display (HUD) systems are widely used in vehicles to overlay navigation prompts in the driver’s field of view, thereby reducing eyes-off-road time. However, suboptimal information presentation may impose extra cognitive demands and lead to driver distraction. To quantify the effects of key HUD navigation design factors on navigation task performance and cognitive workload, a 2 × 2 within-subjects experiment was conducted, manipulating display position (upper vs. lower visual field) and the presence of textual navigation information (with vs. Without text). Thirty university students with driving experience completed navigation tasks under four conditions in a single-lane urban driving simulation. Each task lasted 2–4 min and included six turning prompts. Task performance (accuracy, mean reaction time, and total driving time), subjective workload (PAAS), and eye-tracking measures (mean fixation duration, mean pupil diameter, fixation count, and fixation count proportion) were collected and analyzed using repeated-measures ANOVA. Results showed that display position significantly affected driving efficiency and subjective workload: lower-field displays produced shorter reaction times and lower PAAS scores, while accuracy and total driving time showed no significant differences. Eye-tracking results indicated higher fixation counts and fixation ratios for lower displays. A significant interaction between display position and text was observed for mean fixation duration, whereas mean pupil diameter showed no significant effects. These findings indicate that display position is a critical factor in HUD navigation design, while textual information primarily influences visual inspection patterns rather than overall navigation task performance.
Fang et al. (Thu,) studied this question.