This article reports on a study that focused on a driver’s ability to respond to the deceleration of the car ahead as a factor in rear-end collisions. The study included two experiments: a measurements of the effects of optic flow information and discrete visual and auditory warnings (brake lights, tones) on responses to deceleration during car following; and a measurement of responses to deceleration after a visual interruption. In the first experiment, during computer simulations of car-following scenes, university students pressed a button when the lead car decelerated. Both visual and auditory warnings affected responses. Observers relied on discrete warnings when optic flow information was relatively less effective as determined by the lead car’s headway and deceleration rate. The second experiment included simulation scenes that were designed to tease apart the role of expectations and optic flow. Responses mostly were consistent with optic flow information presented after the interruption rather than with putative mental expectations that were set up by the lead car’s motion prior tothe interruption. The authors discuss the theoretical implications of these results, concluding that responses to deceleration are based on multiple sources of information, including optical size, optical expansion rate and tau, and discrete warnings that are independent of optic flow. They also consider the practical implications of the results which support a role for adaptive collision-warning systems. (Author/publisher)
Abstract