Framing Effects on Distance Perception in Rear-Vision Displays

The increasing availability of camera-based displays for indirect vision in vehicles is providing new opportunities to supplement drivers' direct views of the roadway and surrounding traffic, and is also raising new issues about how drivers perceive the positions and movements of surrounding vehicles. We recently reported evidence that drivers' perception of the distance to rearward vehicles seen in camera-based displays is affected not only by the visual angles subtended by the images of those vehicles, but also by the sizes of those images relative to the sizes of the displays within which they are seen (an influence that we have referred to as a framing effect). There was also evidence for a similar, but weaker, effect with rearview mirrors. In this paper we further investigate the possibility of framing effects in rearview mirrors by comparing distance judgments made in a typical center rearview mirror (with a larger frame size) to judgments made in a typical driver-side rearview mirror (with a smaller frame size). Distance judgments were the same in the two mirrors; there was no evidence for a framing effect. Current results do not provide a definitive explanation for the apparent difference in framing effects between rearview mirrors and camera-based displays. Among the issues that should be addressed by future work are the possibility that frame effects are generally weaker with large displays and the possible role of learning in how people perceive distance in camera-based displays.