Which driver decision-making process do optical speed bars exploit to improve roadway safety, and why?

• A. Intuitive decision making ; the placement of the bars causes drivers to unconsciously perceive an increase in speed, inducing them to slow down
• B. Deliberate decision making ; drivers calculate speed by bar spacing
• C. Habitual decision making ; drivers ignore bars
• D. Emotional decision making ; drivers feel excited

Answer: (A)

The effect of optical speed bars is to change how drivers automatically perceive their own speed through visual cues. As the car passes the bars, the scene creates an unconscious impression that speed is increasing, which prompts the driver to slow down without actively calculating or measuring anything. This relies on quick, automatic judgments rather than careful, deliberate analysis of bar spacing. The approach isn’t about habit or emotion; it’s about perceptual processing guiding fast, intuitive speed adjustment for safety.