Car backlight position and fog density bias observer-car distance estimates and time-to-collision judgments

A series of experiments assessed biases in perceived distance that occur while driving as a function of the backlight position of the car ahead and fog density.

V. Cavallo, M. Colomb, and J. Doré (2001) have shown that smaller horizontal backlight separation and fog may result in increased estimates of the distance between an observer and a car of which only the backlights are visible. They also predicted that raising the height of the car backlights would lead to increasing distance estimates.

Distance perception was assessed in both static and dynamic computer-simulated scenarios in which the distance estimates were performed using a familiarized analog scale or using time-to-collision judgments for both pairs of backlights and single backlights.

In a series of five experiments, the horizontal separation and fog density effects were replicated. In addition, distance estimates were consistently larger with higher than with lower vertical backlight positions.

There is reason to believe that biases in distance perception may be augmented by car backlight positions and by low-visibility weather conditions.

Car designers should take backlight placement seriously. Speed-dependent car-to-car distance control systems seem desirable to counteract biases in distance perception.