We report two experiments that investigate the impact of rear-view mirror distance and curvature on distance, spacing, and time-to-contact (TTC) judgements. The variation in mirror distance had a significant effect on TTC judgements, but only marginally influenced distance and spacing estimations. As mirror distance increased, TTC was overestimated, which is potentially dangerous. Control conditions with identical visual angles across different mirror distances revealed that effects were not solely caused by variation in visual angle. The impact of mirror curvature moderated the effect. While observers were unable to compensate for the mirror distance effect, they could do so for the distortions generated by non-planar mirrors, at least up to a certain degree of distortion. Implications for vehicle design and national guidelines are discussed.
Practitioner summary: Regulations regarding rear-view mirrors are vastly different between countries. For instance EU regulations encourage convex driver-side mirrors, whereas US regulations allow them merely on the passenger's side. The use of a dynamic TTC paradigm puts the human factors designer in a position to evaluate the existing regulations and to design safer mirrors.