Car Backlight Positions and Fog Density Bias Observer-Car Distance Estimates and Time-to-Collision Judgments.

In this study, a series of experiments was conducted to assess biases in perceived distance that occur while driving as a function of the backlight position of the car ahead and fog density. 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 single backlights and pairs of backlights. The horizontal separation and fog density effects were replicated in a series of 5 experiments. Distance estimates were consistently larger with higher vertical backlight positions. These findings indicate that biases in distance perception may be augmented by car backlight positions and by low-visibility weather conditions.