Using perceptual cues for brake response to a lead vehicle: Comparing threshold and accumulator models of visual looming.

•Several effects of situation urgency on brake response time, previously observed separately, were replicated in one single simulator study.•Mechanistic models of brake timing, based on visual looming, were fitted to the human response times.•A looming threshold model was not able to capture the distribution of brake response times.•A model accumulating evidence from both visual looming and brake light onset provided the best fit to the data.•All models fitted the data better when quantifying looming cues as relative optical expansion rather than as optical expansion directly.